DRC-2011-007244 - 0901a0688025fc2e

Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel : [phone]
Fax : [phone]
www.denisonmines.com

August 18, 2011

VIA PDF and FEDERAL EXPRESS

Mr. Rusty Lundberg
Executive Secretary
Utah Division of Radiation Control
Utah Department of Environmental Quality
195 North 1950 West
Salt Lake City, UT 84116-3097

Re: Nitrate Investigation Revised Phase 2 to 5 Work Plan -- Nitrate Investigation at the
White Mesa Mill Site -- Docket No. UGW09-03

Dear Mr. Lundberg:

Pursuant to page 8 paragraph 7of the Final Tolling Agreement, dated June 30, 2011, between
Denison Mines (USA) Corp. (“Denison”) and the Co-Executive Secretary of the Utah Water
Quality Board (the “Tolling Agreement”), please find enclosed Denison’s revisions (Rev. 2),
dated August 18, 2011, to the Nitrate Investigation Revised Phases 2 Through 5 Work Plan Rev.
1.0, White Mesa Mill Site, Blanding Utah (the “Plan”).

This revision has been prepared in response to comments from Utah Division of Radiation
Control (“DRC”) and URS Corporation dated August 11, 2011. The revision has been provided
in both clean and track changes (“redline”) format for ease of review.

The responses to comments are summarized below. Each response has been identified by the
number of the corresponding comment in the August 11, 2011 letter.

1. No response required.

2. Reference to the effects of the Mancos paleoridge have been removed from the “known
conditions” in Section 2.3.3.1.

3. Text has been added to the “decision process” subsections in Section 2.3.3.1 referring to
twice background as defined in Section 3.3.1.

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4. Denison has chosen not to use any archived samples. The text has been modified to
remove references to archived samples.

5. The method number has been changed as requested.

6. Denison agrees with DRC that proper selection of the number and locations of the deep
borings cannot be determined until after resolution of the open issues associated with the
Phase 1 data. Therefore, as requested, Denison plans to prepare a formal report which:
a. Provides all laboratory data including EDDs.
b. Addresses the statistics used to calculate background.
c. Describes and justifies all assumptions and calculations used in developing the
preliminary mass balance.
d. Includes other pertinent review information, such as a QA/QC analysis of the
data.
This report was neither required nor anticipated in the Tolling Agreement. In order to
address DRC’s requirements, Denison will submit this report by September 16, 2011,
which is the earliest date Denison believes is realistic in order to properly address the
issues raised by DRC. The locations for Phase 3 sampling will be determined by
Denison, with DRC approval, following DRC review of this report. To accommodate
this, we have adjusted the schedule in Table 1 accordingly.

7. As mentioned above Denison agrees with DRC that the proper selection of the number
and locations of the deep borings cannot be determined until after resolution of the issues
associated with the Phase 1 investigation results, and has opted to resolve those issues
prior to selecting the locations for Phase 3 coring. As a result, the locations for Phase 3
coring will be determined by Denison, with DRC’s approval, following DRC review of a
Phase 1 data report in accordance with the revised schedule provided in Table 1.

8. As indicated in the text, for all deep bedrock borings drilled in Mill site=related sources,
the depth of each will extend to the upper geologic contact of the Brushy Basin Member
of the Morrison Formation. Language to that effect has been added to Section 3.3.1 of
the Plan. However, Denison believes it is premature at this time to determine whether
any of those borings should be retained as permanent monitoring wells. As a result,
Denison does not intend to complete any of the borings as monitoring wells during Phase
3.

9. Denison agrees that, although not required nor anticipated in the Tolling Agreement, the
results for Phases 2, 3, 4 and 5 need to be provided to DRC for review prior to making
any determinations relevant to subsequent phases. For example, the results of Phase 1
need to be reviewed prior to making determinations on the locations for Phase 3. The
results for Phases 3 and 4 need to be reviewed prior to making determinations prior to
Phase 5. Based on your comments referred to in item 6 above, which demonstrate the
limitations inherent in dealing with draft or preliminary data, Denison believes that it
only makes sense to provide DRC with a formal data report after each Phase. This will

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allow Denison to present data to DRC that can be relied upon to make proper
determinations. The schedule in Table 1 has been revised to accommodate the
preparation of these documents and follow up meetings with DRC staff to review the
results and make relevant determinations for subsequent phases. Deadlines for Phases 2,
3, 4, and 5 results have been provided in the revisions to Table 1.

10. The discussion has been expanded to address how isotope compositions will be
evaluated, as requested.

11. Section 5 and 6 of the Tolling Agreement contemplate that the Phase 4 and Phase 5 QAPs
would be prepared subsequent to finalization of the Plan, and that finalization of those
QAPs is not required prior to execution and delivery of the revised or replacement
Consent Agreement. It has not been possible to develop these QAPs within the 7 days
between DRC’s request and today’s date. The Phase 4 and Phase 5 QAPs will be
provided according to the schedule provided in Table 1.

12. The text has been revised.

13. Denison disagrees that adding additional sampling at this time for hydrogen and oxygen
isotopes in groundwater is critical. The δD and δ18O ranges for groundwater at the site
are already adequately known for this phase of work from the previous study by Hurst
and Solomon (2008). Secondly, Denison disagrees with DRC that the mixing of surface
water and groundwater can be characterized as only a two endmember mixing problem.
These local surface water sites will vary continually in isotopic composition with
evaporation, rainfall, inflow, and anthropogenic additions. Even more important is the
fact that no δD and δ18O values are extant for historical compositions that actually would
be a component of the water now present in the perched aquifer if percolation had
occurred. Furthermore, coupling this variation with the known large variation in
groundwater isotopic signature, the relationship between surface and groundwater
isotopic content may not be sufficiently definitive in identifying the origin of the nitrate
plume. Thirdly, Denison does not concur that the groundwater isotopic composition is
“critical for evaluating the oxygen isotopes’ composition of sulfate and nitrate.” This
presumes groundwater has a unique signature, that the local groundwater participated in
nitrification, and that the groundwater currently associated with the nitrate was the water
source in the nitrification process. Denison believes that all three of these assumptions
are unsupported at present.

For the foregoing reasons, sampling for hydrogen and oxygen isotopes has not been
added to the plan, and the text has not been changed.

14. The methods have been changed to reflect those used in Phase 1.

15. Your comments appear to: 1) assume that a generic simplified rendition of the
nitrification process applies to the mill site environment, and 2) assert that the isotopic

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signature will be definitive or “…much different…” between two preselected
endmembers. We believe these comments make many assumptions and are incorrect in a
number of details and that they could represent bias in predetermining the nitrate source
as either nitric acid or nitrification occurring only at the mill site. Denison believes it is
more appropriate to use the currently developed conceptual model, with multiple
potential sources, as identified in the workplan and, after collection and analysis of the
data, to examine the hypotheses that constitute options in the conceptual model, and
systematically interpret each for plausibility. More specifically, we believe the following
matters should be considered because they emphasize the need to apply a broader view of
the exchange mechanism as the data are interpreted:

a. The word “exchange” used in the statement referenced in section 3.4 of the
subject document was not intended to refer only to the molecular reaction
pathways for 18O isotopic exchange in the formation, evolution and longevity of
nitrate and sulfate. Rather, the word “exchange” was used in its broadest sense of
exchanging oxygen from one reservoir to another, e.g. water or atmosphere to
nitrogen or sulfate molecules. Movement of oxygen from one reservoir to another
can involve many reaction pathways both in natural environments, as well as in
the many extreme manufacturing processes that are responsible for nitrate and
sulfate products on site, and the oxygen reservoirs are numerous (H2O, O2, SO2,
SO3, SO4, NH2OH, NO2, NO3, etc.). The exchange of oxygen also includes the
specific mechanism of atomic level isotopic oxygen exchange between molecules.
However, contrary to the DRC statement dismissing isotopic exchange at the
molecular level for this site, the process is actually not limited to low pH solutions
and is, in contrast, specifically appropriate with respect to the nitrification
processes that occur at this site. Molecular level isotopic exchange does in fact
occur between 18O-H2O and 18O-NO2, and 18O-NO3, both before and after the
final oxidation step of NO2 to NO3. Isotopic exchange of oxygen in water with
oxygen in the nitrite molecule is a process that is well documented over a broad
pH range, and is important even in alkaline marine environments, which DRC
appears to incorrectly dismiss as occurring only in acid pH ranges.

b. Oxygen isotopic exchange is further significant for this site because at the
conclusion of nitrification, isotopic exchange has removed from the nitrate
molecule some of the oxygen molecules that were incorporated during ammonium
oxidation, effectively diminishing the percentage of O2 derived oxygen in nitrate
from a 1:2 ratio to as much as 1:6, altering the convention of a rigid 1:2
stoichiometry as being definitive.

c. The incorporation of oxygen during the ammonium oxidation step and the nitrite
oxidation step, and the reactions with oxygen and water are kinetic processes with
attendant isotopic fractionation that can yield significantly different final 18O-
NO3 values, depending on the extent to which these reactions have progressed.
This fractionation yields different end results for the 18O-NO3 value

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complicating the interpretation of the nitrogen source using the 18O-NO3
signature.

d. It should not be assumed that the nitrification process occurred at the Mill Site
and that it will be definitively distinct from nitric acid or conversely similar if not
identical to all other nitrate sources derived from the nitrification process that are
non-nitric acid in origin. Clearly ammonium from fertilizers, human waste from
municipal sources, animal waste, human and lab waste in septic discharges, etc.
that may or may not originate at the Mill site are potential sources of nitrate, and
the nitrification can have occurred in remote locations with broadly varying 18O
ratios in the water that participates in the reaction. Consequently, nitrate may
have arrived at the Mill site carried by fugitive off-site water sources that are now
mixed with nitrogen on-site from many other sources.

e. The use of the term “exchange” also fits the modification of 18O in sulfur
species. This project is considering how to differentiate sources of sulfate as
forensic indicators of water sources. The isotopic label of oxygen in sulfate may
be derived from many natural as well as manufactured sources, under both
oxidizing and reducing conditions, but this oxygen component of sulfate may
have been exchanged as well. 18O-SO4 exchange occurs as SO2 and SO3 are
oxidized, in high temperature or low pH environments during manufacturing
processes. Even in the reduction of sulfate by bacterial processes in ambient
temperatures and alkaline pHs, the residual sulfate experiences 18O-SO4
enrichment from exchange due to intercellular processes.

f. Nitric acid itself, where present on the site, may have 15N and 18O-NO3 values
that are variable and may not have a reliable endmember signature depending on
manufacturing process and source. Nitric acid is manufactured by reacting
ammonia with O2 at high temperature and pressure to form NO2 which is
dissolved in water to make HNO3. Further purification is possible, but not
required, by exposing any of the unreacted NO2 to O2, producing additional
HNO3. It should not be assumed that the nitric acid isotopic signature is
unequivocal, derived only from atmospheric O2 with a fixed 18O-NO3 signature
and definitively different from other sources of nitrate.

Denison does not agree with the assumption that infers the sources of nitrate at the mill
site can be narrowed to two endmembers, one of which is site-related nitrification and the
other is nitric acid. Nor does Denison believe that it should be assumed that conventional
stoichiometry for acquisition of O2 and H2O in nitrate is 1:2 and thus a definitive
identifier for this site; isotopic exchange modifies that ratio and shifts the 18O-NO3.
Further, Denison believes that isotopic exchange reactions may be important at the mill
site for nitrate or for sulfate as components of the forensic tools to be used at this site in
defining the range of 18O-NO3 or d18O-SO4 for testing the conceptual model.

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The workplan has been revised to discuss the appropriate range of phenomena and
processes to be considered.

16. The proposed schedule was developed in good faith, contains no delays, and represents
the minimum time required a) for Denison to address every requirement in the Tolling
Agreement and b) to provide Denison a fair and reasonable opportunity to draw and
present objective and defensible conclusions from the investigation. Every effort has
been made to compress timeframes, while at the same time accommodating additional
requirements and deliverables requested by DRC. We think the revised schedule is as
aggressive as we can make it, and in fact is more compressed than would normally be
considered reasonable for a proper objective investigation of this sort. We do not believe
it is possible to properly perform the investigation on a more compressed timetable.

The revised timetable is somewhat shorter than the timetable proposed in earlier versions
of the Phase 2 to 5 Plan, yet accommodates additional steps not addressed in the Tolling
Agreement. Factors that must be taken into account are: (a) the results of Phase 1 must
be analyzed prior to make field determinations for Phase 3; (b) the results of Phases 3 and
4 must be analyzed prior to making determinations for Phase 5; (c) it is not realistic or
safe to expect that the Phase 5 field work can be performed properly during the winter
months. The Mill has always taken the position that this type of field work cannot be
scheduled during the winter months due to field condition and safety concerns; and (d)
the types of isotopic analyses contemplated require longer turnaround times than more
conventional analyses.

The revised schedule has been presented in Table 1.

17. Figures 16, 17, and 18 address evaluation of sources and appropriately refer to Phase 5.
Figure 19 addresses groundwater and, as you noted, mistakenly referred to Phase 5. It
now appropriately refers to Phases 2 and 4. In the revised Figure 19, all outcomes of
Phase 2 sampling now flow to Phase 4 sampling, and each outcome of Phase 4 sampling
now flows to the appropriate potential source logic diagram. Thus, isotopic fingerprints
that do not match military or agricultural uses of the site now flow to both the natural
nitrate reservoir and the potential process related logic diagrams.

18. Please see item 16 above.

If you have any further questions please contact me at 303-389-4132.

Yours very truly,

7

Jo Ann S. Tischler
Director, Compliance and Permitting

Enclosure.

cc Robert D. Baird, URS
Daniel W. Erskine, Ph.D, INTERA
David C. Frydenlund
Ron F. Hochstein
Harold R. Roberts
David E. Turk
Katherine A. Weinel

NNIITTRRAATTEE IINNVVEESSTTIIGGAATTIIOONN RREEVVIISSEEDD
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White Mesa Mill Site
Blanding, Utah

Prepared for:

Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, Colorado 80265

Prepared by:

6000 Uptown Boulevard NE, Suite 220
Albuquerque, New Mexico 87110
August 18, 2011

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah i August 18, 2011
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TABLE OF CONTENTS
LIST OF FIGURES ..................................................................................................................... iv
LIST OF TABLES ....................................................................................................................... iv
LIST OF APPENDICES .............................................................................................................. v
ABBREVIATIONS AND ACRONYMS .................................................................................... vi
1.0 INTRODUCTION............................................................................................................. 1
1.1 Problem Definition.................................................................................................. 4
1.1.1 Purpose of the Investigation........................................................................ 4
1.1.2 Site Description and Background ............................................................... 6
1.1.3 Summary of Previous Investigations .......................................................... 8
1.2 Project Description.................................................................................................. 9
1.2.1 Project Objectives ....................................................................................... 9
1.2.2 Project Measurements ............................................................................... 10
1.3 Quality Objectives ................................................................................................ 11
1.3.1 Precision .................................................................................................... 11 1.3.2 Accuracy ................................................................................................... 11
1.3.3 Representativeness .................................................................................... 11
1.3.4 Completeness ............................................................................................ 12
1.3.5 Comparability ........................................................................................... 12
1.3.6 Detection and Quantitation Limits ............................................................ 12
1.4 Project Organization ............................................................................................. 12
1.4.1 Functional Groups ..................................................................................... 12
1.4.2 Overall Responsibility for the QA/QC Program ....................................... 13
1.4.3 Data Requestors/Users .............................................................................. 13
1.4.4 Data Generators ........................................................................................ 13
1.5 Special Training and Certification ........................................................................ 15 1.6 Documents and Records ....................................................................................... 15
1.6.1 Field Documentation ................................................................................. 15
1.6.2 Reports Generated ..................................................................................... 15
2.0 CONCEPTUAL SITE MODEL .................................................................................... 16
2.1 Site Summary ........................................................................................................ 16 2.2 Site Description ..................................................................................................... 16
2.2.1 Identify Contaminants ............................................................................... 16
2.2.2 Establishing Background Concentrations of Contaminants ..................... 16
2.2.3 Source Locations, Boundaries, and Volumes ........................................... 17 2.2.4 Time of Initiation, Duration, and Rate of Contaminant Release .............. 18

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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2.3 Migration Pathway Descriptions........................................................................... 19
2.3.1 Soil and Bedrock ....................................................................................... 22
2.3.2 Groundwater ............................................................................................. 22
2.3.3 Specific Source Locations and Data Needs .............................................. 22
2.4 Environmental Receptor Identification ................................................................. 84
2.4.1 Humans ..................................................................................................... 84
2.4.2 Ecological ................................................................................................. 84
3.0 DATA GENERATION AND ACQUISITION ............................................................. 85
3.1 Phase 1 Geoprobe Investigation of Background, Natural Nitrate Reservoir, and
Potential Site Sources ........................................................................................... 85 3.2 Phase 2 Groundwater Quality Sampling and Analysis ......................................... 85
3.2.1 Sampling Design ....................................................................................... 85
3.2.2 Field Activities and Sampling Methods .................................................... 86
3.2.3 Sample Containers and Holding Times .................................................... 87
3.2.4 Analytical Methods ................................................................................... 87
3.3 Phase 3 Deep Bedrock Core Sampling and Analysis ........................................... 87
3.3.1 Sampling Design ....................................................................................... 88
3.3.2 Field Activities and Sampling Methods .................................................... 89
3.3.3 Sample Containers and Holding Times .................................................... 90
3.3.4 Analytical Methods ................................................................................... 90
3.4 Phase 4 Stable Isotopic Sampling and Analysis of Groundwater in
Existing Wells ....................................................................................................... 90
3.4.1 Sampling Design ....................................................................................... 91
3.4.2 Field Activities and Sampling Methods .................................................... 93
3.4.3 Sample Containers and Holding Times .................................................... 94 3.4.4 Analytical Methods ................................................................................... 94
3.5 Phase 5 Isotopic Soil Sampling and Analysis ....................................................... 94
3.6 Sample Handling and Custody.............................................................................. 96
3.6.1 Sample Labeling ....................................................................................... 96
3.6.2 Sample Documentation ............................................................................. 96 3.6.3 Chain of Custody ...................................................................................... 97
3.6.4 Sample Shipment ...................................................................................... 98
3.7 Quality Control ..................................................................................................... 99
3.7.1 Field Quality Control Methods ................................................................. 99
3.7.2 Analytical Laboratory Quality Control Methods ...................................... 99 3.7.3 Internal Quality Control Checks ............................................................. 100
3.7.4 Instrument Equipment Testing, Inspection, and Maintenance................ 101
3.7.5 Instrument Calibration ............................................................................ 101

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4.0 DATA EVALUATION ................................................................................................. 102
5.0 AUDITS ......................................................................................................................... 103
5.1 System Audits ..................................................................................................... 103
5.2 Performance Audits ............................................................................................ 103
5.3 Follow-Up Actions.............................................................................................. 103
5.4 Audit Records ..................................................................................................... 103
6.0 REFERENCES .............................................................................................................. 104

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LIST OF FIGURES
Figure 1 Map Showing Location of White Mesa Mill Site
Figure 2 Map Showing Nitrate Plume
Figure 3 Map Showing Chloride Plume
Figure 4 Map Showing Nitrate and Chloride Plumes Together
Figure 5 Nitrate Plume Overlain on 1968 Aerial Photograph Figure 6 Kriged 1st Quarter, 2011 Nitrate (mg/L) (Nitrate + Nitrite as N) and Locations
of Cross–Sections SW-NE, NW-SE, and SW2-NE2
Figure 7 Interpretive Northeast-Southwest Cross Section (NE-SW) White Mesa Site
Figure 8 Interpretive Northeast-Southwest Cross Section (NE2-SW2) White Mesa Site
Figure 9 Interpretive Northwest-Southeast Cross Section (NW-SE) White Mesa Site Figure 10 Elevation of Bedrock Surface Showing Thickness of Mancos Shale and Cross
Sections SW-NE, NW-SE, and SW2-NE2
Figure 11 Isopach Map Showing Thickness of Mancos Shale and Potential Nitrate
Sources
Figure 12 Potential Natural Nitrate Reservoir Source Figure 13 Potential Process-Related Source Where Mancos is Thin
Figure 14 Potential Process-Related Source Where Mancos is Thick
Figure 15 Potential Pond or Pond-Like Source
Figure 16 Logic Diagram for Potential Natural Nitrate Reservoir Source Investigation
Figure 17 Logic Diagram for Potential Process Related Source Investigation Figure 18 Logic Diagram for Potential Pond and Pond-Like Source Investigation
Figure 19 Logic Diagram for Groundwater Investigation
Figure 20 Diagram for Conceptual Site Model (CSM)
Figure 21 Phase 2 Groundwater Sampling Locations
Figure 22 Phase 3 Potential Coring Locations Figure 23 Phase 4 Groundwater Sampling Locations

LIST OF TABLES
Table 1 Work Plan Schedule
Table 2 Summary of the Most Recent Chloride and Nitrate Concentrations in
Groundwater
Table 3 Phase 2 Groundwater Sampling Locations Table 4 Phase 3 Coring Sample Locations
Table 5 Phase 3 Coring Laboratory Analytical Parameters
Table 6 Phase 4 Groundwater Sampling Locations

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LIST OF APPENDICES
Appendix A INTERA Standard Operating Procedure 11 and U.S. Bureau of Reclamation’s
Engineering Geology Field Manual
Appendix B Field Forms
Appendix C ASTM E1689-95(2003)e1 Standard Guide for Developing Conceptual Site
Models for Contaminated Sites Appendix D Standard Operating Procedures for Isotope Analysis

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ABBREVIATIONS AND ACRONYMS
Additional Studies Additional studies to be performed by DUSA in order to complete
the CIR
Agreement States State agencies authorized to implement the U.S. Nuclear
Regulatory Commission’s licensing program under the Atomic
Energy Act amsl above mean sea level
Analysis Monitor employee or agent of the Analytical Laboratory
Analytical Laboratory contract analytical laboratory

bgs below ground surface
CAP Corrective Action Plan
CCD/SX Counter Current Decant/Solvent Extraction
CIR Contamination Investigation Report
cm/s centimeters per second COC chain of custody
Co-Executive Secretary Co-Executive Secretary of the Utah Water Quality Board of the
Utah Department of Environmental Quality
Consent Agreement Stipulated Consent Agreement Docket No. UGW09-03 dated
January 27, 2009 CSM Conceptual Site Model

δ delta
Data Users data requestors/users
DOE U.S. Department of Energy DQO data quality objectives
DRC Utah Division of Radiation Control
DUSA Denison Mines (USA) Corp.

EPA U.S. Environmental Protection Agency
ft/yr feet per year

GPS global positioning system
GWDP Groundwater Discharge Permit
ID identification
INTERA INTERA Incorporated

LCS laboratory control sample LU/LC land use/land cover

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MDL method detection limit
mg/kg milligrams per kilogram
mg/L milligrams per liter
Mill White Mesa Mill
NAVLAP National Voluntary Laboratory Accreditation Program
NELAP National Environmental Laboratory Accreditation Program
New Theory A new theory for a possible source of the nitrate and chloride
contamination beneath the Mill, based on DUSA’s review of the
scientific literature NOTICE The October 5, 2010, DRC Notice of Additional Required Action
NRC U.S. Nuclear Regulatory Commission

PG Professional Geologist
Plan and Schedule The plan and schedule for performing Additional Studies and submitting a revised CIR

QA quality assurance
QA/QC quality assurance/quality control
QAP Quality Assurance Plan QC quality control

Request Request for Voluntary Plan and Schedule to Investigate and
Remediate Nitrate Contamination at the White Mesa Mill Site
RPD relative percent difference
SAG Semi Autogenous Grinding
Sampling and QC Monitor Sampling and QC data monitor responsible for sample collection,
record keeping, and QA/QC activities
SHP southern high plains Site White Mesa Mill
SOP Standard Operating Procedure
SPLP Synthetic Precipitate Leaching Procedure

Tolling Agreement A Tolling Agreement dated December 15, 2010, between DUSA and the Co-Executive Secretary

UAC Utah Administrative Code
UDEQ Utah Department of Environmental Quality
USCS Unified Soil Classification System

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1.0 INTRODUCTION
Denison Mines (USA) Corp. (“DUSA”) received a Request for Voluntary Plan and Schedule to
Investigate and Remediate Nitrate Contamination at the White Mesa Mill (the “Mill”) Site, near
Blanding, Utah (the “Request”) from the Co-Executive Secretary (the “Co-Executive Secretary”)
of the Utah Water Quality Board, of the Utah Department of Environmental Quality (“UDEQ”)
on September 30, 2008. In the Request, the Co-Executive Secretary noted that groundwater
nitrate as nitrogen levels have exceeded the State water quality standard of 10 milligrams per
liter (“mg/L”) in certain monitoring wells at the Mill Site. For the remainder of this document,
any reference to nitrate or ammonium, whether or not the reference specifies “as N,” means the
analyte “as nitrogen.”
As a result of the Request, DUSA agreed to submit a plan of action and a schedule for Co-
Executive Secretary approval for completion of a Contamination Investigation Report (“CIR”) to
determine the physical cause(s), location(s), transfer mechanism(s), and characteristics of all
source(s) of the nitrate contamination in order to form a basis for and facilitate later submittal of
a groundwater Corrective Action Plan (“CAP”) that meets the requirements of Utah
Administrative Code (“UAC”) R317-6-6.15D, or to demonstrate conclusively that DUSA did not
cause or contribute to the nitrate contamination in any manner and that, as a result, such a CAP is
not necessary. Subsequently, in a letter dated December 1, 2009, UDEQ, noting that elevated
chloride concentrations exist, apparently coincident with elevated nitrate concentrations,
recommended that DUSA also address and explain the elevated chloride concentrations.
DUSA and the Co-Executive Secretary entered into a Stipulated Consent Agreement Docket No.
UGW09-03, dated January 27, 2009 (“Consent Agreement”), related to nitrate contamination at
the Mill. Pursuant to Item 6.A of the Consent Agreement, DUSA submitted a Nitrate CIR for the
White Mesa Uranium Mill Site, Blanding, Utah, dated December 30, 2009, to the Utah Division
of Radiation Control (“DRC”). By a letter dated October 5, 2010, the Co-Executive Secretary
notified DUSA of his determination that the CIR is incomplete.
By an email transmitted to the Co-Executive Secretary on October 20, 2010, and pursuant to
Item 11 of the Consent Agreement, DUSA requested that the deadline stipulated in item 7.C of
the Consent Agreement be amended as follows:
a. DUSA representatives would meet with the Co-Executive Secretary and his legal counsel
within two weeks from the date of the email to discuss the legal responsibilities of DUSA
with respect to the nitrate contamination.
b. Once the legal responsibilities of DUSA with respect to the nitrate contamination have
been determined, DUSA would, within 30 days after such a determination was made,

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submit to the Co-Executive Secretary for approval a plan and schedule to perform any
further investigations that may be required in order to remedy any such omissions,
content requirements, or failures of performance standards, and to submit a revised CIR.
c. DUSA would perform such investigations and submit a revised CIR in accordance with
the agreed upon plan and schedule.
At an October 26, 2010, meeting with the Co-Executive Secretary, DRC staff, and legal counsel,
DUSA reported that it was premature to submit a schedule for submittal of performance
standards and a CAP for the nitrate contamination. In turn, DUSA presented a new theory for a
possible source of the nitrate and chloride contamination beneath the Mill, based on DUSA’s
review of the scientific literature (“New Theory”), specifically, that the nitrate contamination
source is or could be caused by naturally occurring nitrate and chloride salt deposits located in
the vadose zone near or beneath the Mill Site area, which have been mobilized by natural and/or
artificial recharge. The parties agreed that this New Theory warranted additional investigation,
along with certain of the other additional studies suggested in the October 5, 2010, DRC Notice.
DUSA submitted via email on November 15, 2010, a letter setting out the additional studies to be
considered that have been identified to date, including the additional studies suggested in the
October 5, 2010, DRC Notice, and proposed additional studies relating to the New Theory, and
other additional studies that DUSA believes may be relevant. At a November 30, 2010, meeting
between DRC Staff and DUSA technical and regulatory staff, DUSA presented a number of
additional studies (herein “Additional Studies”) to be performed by DUSA in order to complete
the CIR. The Co-Executive Secretary and DUSA further agreed that DUSA would prepare a
detailed plan and schedule (the “Plan and Schedule”) for performing such studies and for
submittal of a revised CIR that meets the requirements of all applicable regulations on or before
February 15, 2011. During the November 30, 2010, meeting, it was agreed that both the Plan and
Schedule and the revised CIR will be subject to Co-Executive Secretary approval. DUSA’s
commitment to prepare and submit the Plan and Schedule is set out in a Tolling Agreement (the
“Tolling Agreement”) dated December 15, 2010, between DUSA and the Co-Executive
Secretary.
DUSA submitted a draft Work Plan on February 14, 2011. During subsequent discussions with
DRC staff, the Co-Executive Secretary and DUSA agreed that the additional studies could
require as many as five phases, and the schedule should include points of consultation between
phases at which the Co-Executive Secretary and DUSA could evaluate and agree on the
redirection, addition, or elimination of subsequent phases.
The Tolling Agreement was revised on April 28, 2011, to allow time for:

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• DUSA to prepare and submit a Revised Work Plan for Phase 1 (the final was submitted
May 13, 2011).
• DUSA to prepare and submit a revised Work Plan for Revised Phases 2 through 5 (by
June 3, 2011), including a Conceptual Site Model (“CSM”) of potential nitrate sources.
• The Co-Executive Secretary to review and approve the revised Work Plans, including
modifications.
• The Co-executive Secretary and DUSA to agree on a revised or replacement Consent
Agreement that incorporates the deliverables and timelines in the approved Phase 2
through 5 Work Plan.
The tolling agreement was finalized on June 30, 2011.
This document is the revised Work Plan for Phases 2 through 5, which is being submitted in
accordance with the Final Tolling Agreement and which contains information for the execution
of Phases 2 through 5 as described in the Final Tolling Agreement. The Phases 2 through 5
Work Plan requirements specified in the Final Tolling Agreement Section 6 are shown below.
6. Phase 2 through 5 Work Plan Rev. 1.0– on or before August 4, 2011, DUSA shall
complete and submit for Co-Executive Secretary review and approval a Revised Phase 2
through 5 Work Plan Rev. 1.0, which will include, but is not limited to:
a) Detailed description of the activities, equipment, procedures, performance
objectives, and decision criteria involved in each Phase, including, but not limited
to a description and incorporation by reference of the Phase 2 Detailed Work Plan
and Schedule and a description of the agreed details and schedules relating to
Phases 4 and 5.
This revision includes, by reference, the Phase 2 Detailed Work Plan, and provides
agreed upon details of Phases 4 and 5.
b) An initial CSM of the facility (Revision 0), that DUSA will use as a guide to
plan/conduct the Nitrate Investigation.
This is addressed as Section 2.0 of this document.
c) A logic diagram for each Phase to identify all studies and decision processes that
may be required to meet all applicable regulatory requirements including the
performance objectives of the Consent Agreement, Item 6(A)(iv).

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Logic diagrams are attached as figures to this work plan.
d) Deadlines for commencement and completion of all field and laboratory work for
each Phase, and the final CIR report preparation.
Deadlines are provided on the schedule included as Table 1 to this document.
e) Deadline for submittal of a final revised CIR for Co-Executive Secretary review
and approval.
Deadlines are provided on the schedule included as Table 1 to this document.
1.1 Problem Definition
1.1.1 Purpose of the Investigation
Based on discussions culminating in the Revised Tolling Agreement, DRC and DUSA have
agreed to conduct the nitrate investigation in phases. The multi-phased program is designed to
evaluate a number of potential sources of nitrate and chloride that may have contributed to the
identified plume, including Mill-related sources, non-Mill-related sources, and sources resulting
from historical use. The phased approach will include development of a CSM that will be
refined as the investigation progresses and will be used by DRC and DUSA at several decision
junctures to:
1. Determine which sources should be removed from further consideration.
2. Assist in quantifying the relative contribution of the remaining sources.
3. Determine whether or not to proceed with future phases of the investigation.
The Phase 1 investigation is described in detail in the Nitrate Investigation Revised Phase 1
Work Plan, White Mesa Mill Site, dated May 13, 2011 (INTERA, 2011). The Phase 2
investigation is described in detail in the White Mesa Uranium Mill Phase 2 Nitrate Investigation
Detailed Work Plan and Schedule, dated July 12, 2011.
This work plan describes the remaining phases of the investigation per the Final Tolling
Agreement. Each of the phases contemplated by the Final Tolling Agreement is described
briefly below. The purpose of Phases 2 through 5 is to collect data to fill the data gaps, test
hypotheses, and update the CSM as described above. Additional plans, as delineated below, will
be submitted to address the specific details, activities, equipment, procedures, objectives, and
decision criteria for each of the phases specified in the Final Tolling Agreement.

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1.1.1.1 Phase 2 – Groundwater Quality Sampling and Analysis
This phase of the investigation will collect groundwater samples from existing on-site wells.
Groundwater will be analyzed for specific compounds associated with military activities at the
Site and with agricultural use at the Site. A separate Phase 2 Detailed Work Plan and QAP for
conventional groundwater sampling and analysis has been submitted which provides the specific
details, activities, equipment, procedures, objectives, and decision criteria for this phase of the
investigation. The QAP is based upon the existing DRC-approved QAP for groundwater
sampling at the White Mesa Mill.
1.1.1.2 Phase 3 – Deep Bedrock Core Sampling and Analysis
This phase of the investigation will look at bedrock as a pathway for contaminant migration.
Based on the results of Phase 1, locations will be selected for further analysis to trace nitrate and
chloride from the base of the alluvium into bedrock. The activities associated with Phase 3 of the
nitrate investigation are described herein. Specific location information will be provided at a
later date after the receipt of the analytical data from Phase 1.
1.1.1.3 Phase 4 – Stable Isotopic Sampling and Analysis
Stable isotopes of nitrogen, sulfate, and ammonium will be used to identify and “fingerprint” the
contamination in groundwater and compare it to the fingerprint of nitrate and chloride coming
from potential sources. A separate Phase 4 Detailed Work Plan and QAP for isotopic
groundwater sampling and analysis will be submitted which will provide the specific details,
activities, equipment, procedures, objectives, and decision criteria for this phase of the
investigation. The Phase 4 QAP will be based upon and utilize the existing DRC-approved QAP
for groundwater sampling at the White Mesa Mill. The Phase 4 QAP will follow the same
outline as the approved QAP and will supplement the approved QAP to address those activities
which are specific to Phase 4 of the nitrate investigation.
1.1.1.4 Phase 5 – Isotopic Soil Sampling and Analysis
A determination regarding the necessity to complete Phase 5 will be completed after review of
the data resulting from the previous phases of the nitrate investigation. If completed, Phase 5
will provide an isotopic “fingerprint” of potential sources of nitrate and chloride in process
chemicals, soil, or deep cores. If this phase is required, a separate Work Plan and QAP will be
submitted which will provide the specific details, activities, equipment, procedures, objectives,
and decision criteria for this phase of the investigation. A submittal date for the draft QAP for
this phase will be established if consultation with DRC determines this phase is needed.

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1.1.2 Site Description and Background
The Site is a uranium mill with a vanadium co-product recovery circuit located within the
Colorado Plateau physiographic province approximately 5 miles south of the city of Blanding,
Utah. Mill construction began in 1979, and conventionally mined uranium ore was first
processed in May 1980. Over its 25-year operating history, the Mill has processed over 4 million
tons of conventionally mined and alternate feed uranium ores for the recovery of 25 million
pounds of U3O8 and 34 million pounds of vanadium to date.
Potential on-site sources of nitrate and chloride addressed in the Nitrate CIR (INTERA, 2009)
include:
• The septic leach fields at the Site.
• The municipal sewage plant discharge water used historically as Mill water makeup.
• Livestock activities at the wildlife ponds.
• Livestock activities at the Historical Pond.
• Agricultural activities.
• The former Fly Ash Pond.
• Potential historical spills of ammonium-bearing and/or chloride-bearing process
chemicals.
• A potential breach in the Mill circuit floor drains or tailings transfer lines.
• A potential leak in the Mill’s tailings cells.
1.1.2.1 Site Status
The Mill was in standby status from November 1999 to April 2002. During the standby period,
the Mill received and stockpiled alternate feed materials from the formerly utilized Ashland 1
and Linde remedial action program sites, as well as from other sources of alternate feed
materials.
During the period from April 2002 to May 2003, the Mill processed 266,690 tons of alternate
feed materials. Subsequently, the Mill entered standby mode but continued to stockpile alternate
feed materials.
Uranium mills are licensed to operate either by the U.S. Nuclear Regulatory Commission
(“NRC”) or by state agencies authorized to implement the NRC’s licensing program under the
Atomic Energy Act (“Agreement States”). The Mill received its initial source material license
from the NRC in 1980. The State of Utah became an Agreement State in 2005, at which time

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regulatory authority for the Mill passed to the Utah DRC. The Mill is regulated under Utah
Radioactive Materials License UT 1900479. Groundwater quality is regulated by the Mill’s
Utah Groundwater Discharge Permit (“GWDP”) UGW370004.
The Mill is currently operating, having commenced operations in March 2005 with the
processing of Cameco alternate feed materials. The Mill has since processed natural ores and
alternate feeds. Alternate feeds have been processed both in the main Mill circuit and the
alternate feed circuit, which was constructed in 2009.
1.1.2.2 Physical Setting
The Mill is located near the western edge of the Blanding Basin within the Canyonlands section
of the Colorado Plateau physiographic province. Broad, generally horizontal uplift and
subsequent erosion have produced topography consisting of high plateaus, mesas, buttes,
monuments, and deep canyons incised into the relatively flat-lying Mesozoic and Paleozoic
sedimentary rocks.
Northeast of the Mill Site, igneous intrusions forming the core of the Abajo Mountains have
disturbed the classic flat-lying Colorado Plateau stratigraphy, resulting in uncharacteristic local
folding and faulting of sedimentary rocks. The Abajo Mountains rise to more than 11,000 feet
above mean sea level (“amsl”), and have likely provided a source of sediments to the Mill Site
(5,600 feet amsl) during intrusion and disturbance of older rocks.
Quaternary deposits overlie the sequence of Mesozoic rocks present in the region. The
Cretaceous Mancos Shale and Dakota Sandstone represent the local top of the Mesozoic section
in the region and are underlain by the Lower Cretaceous Burro Canyon Formation. This unit is
underlain in turn by the Jurassic Morrison Formation (which includes the Brushy Basin,
Westwater Canyon, Recapture, and Salt Wash Members), the Summerville Formation, the
Entrada Sandstone, and the Navajo Sandstone. The Navajo is underlain by the Jurassic Kayenta
Formation, which in turn is underlain by the Triassic Chinle and Moenkopi Formations.
Paleozoic sedimentary rocks underlie these Mesozoic units.
Cretaceous geologic units that stratigraphically overlie the Burro Canyon Formation regionally
(Mancos Shale and Dakota Sandstone) have been removed by erosion in the vicinity of the Mill.
Thus, the lower Cretaceous Burro Canyon Formation (already present during the Mid-Tertiary
Abajo igneous intrusive event) is directly overlain by Quaternary deposits at the Mill Site. The
Quaternary colluvial/alluvial sediments are typically coarse-grained deposits that contain little
water. The Burro Canyon Formation is described as interbedded conglomerate and grayish-green
shale with light-brown sandstone lenses deposited in a fluvial environment (Aubrey, 1989). The

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average thickness of the unit is approximately 75 feet (U.S. Department of Energy [“DOE”],
2004).
The Burro Canyon Formation hosts the uppermost occurrence of groundwater at the Mill Site.
Groundwater in this unit is perched (i.e., isolated from groundwater that occurs in geologic units
that underlie the Burro Canyon Formation). Perched water is supported by the relatively
impermeable, underlying, fine-grained Brushy Basin Member of the Morrison Formation. The
permeability of the Burro Canyon Formation is generally low. Some conglomeratic zones may
exist east to northeast of the tailings cells, potentially explaining a relatively continuous zone of
higher permeability. The saturated thickness of the perched groundwater zone ranges from
approximately 82 feet in the northeast portion of the Mill Site to less than 5 feet in the southwest
portion of the Site (DOE, 2004). Groundwater isopleths, based on water level data collected in
2010, indicate that flow in the perched zone is generally from northeast to southwest, although in
the eastern portion of the Mill Site, the gradient has a more southerly component.
Groundwater in the regional Entrada/Navajo aquifer is under artesian pressure (upward flow
gradient), providing a hydrologic barrier to any potential seepage from overlying geologic units.
Perched groundwater within the Burro Canyon Formation is characterized by low yields and is
generally of poor quality, containing moderate to high concentrations of chloride, sulfate, and
total dissolved solids (Hunt, 1996).
1.1.3 Summary of Previous Investigations
Previous investigations with respect to the presence of nitrate in groundwater under the Mill
include a Nitrate and Chloride Source Review Memo (Tischler, 2009), a Nitrate CIR (INTERA,
2009), an Initial Nitrate Monitoring Report (DUSA, 2009), quarterly nitrate and chloride
reporting to the DRC (DUSA, 2010-2011), and ongoing investigations into historical land uses,
which have not yet been published.
The Nitrate and Chloride Source Review Memo (Tischler, 2009) identifies and discusses
potential nitrate sources at the Mill Site, including septic leach fields, municipal sewage plant
discharge water used historically as Mill water makeup, livestock activities at the wildlife ponds
and the Historical Pond, the former Fly Ash Pond, potential historical spills of ammonium-
bearing process chemicals, a potential breach in the Mill circuit floor drains or tailings transfer
lines, Mill laboratories, and a potential leak in the Mill’s tailing cells. The Memo also discusses
potential historical sources and offsite sources. The Memo concludes that the most likely sources
of nitrate and chloride come from upgradient of the current plume in the municipal sewage plant
discharge water used historically as Mill water makeup, from possible livestock activity near the
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Autogenous Grinding (“SAG”) leach field and the Main Leach Field. Since the publication of the
Nitrate and Chloride Source Review Memo, DUSA’s understanding of historical land uses has
continued to be updated through literature, Internet, and other land use studies, which are
discussed below.
Land uses proximal to the Mill include farming, ranching, cattle grazing, and feed and grain
silos. A further evaluation of historical land use in the vicinity of the Site will be performed to
supplement the source evaluation (Source Review Report) (Tischler, 2009) that was included in
the Nitrate CIR. This further evaluation is currently under way and will (a) identify areas that
have been subject to agricultural activities, and (b) evaluate land-use practices that may have led
to elevated levels of nitrate and other contaminants in groundwater. Objective (a) is also required
to identify areas for sampling of buildup of atmospheric nitrogen, since the goal is to sample
areas that have not been subject to human activities. This analysis includes evaluation of
historical aerial photography and historical Landsat satellite imagery, and an Internet-based
search of historical military activities in the region.
The Nitrate CIR (INTERA, 2009) also discusses the potential sources identified in the Source
Review Memo (Tischler, 2009) and describes the sampling design and installation of 19 new
wells used to characterize the nitrate and chloride plumes. The CIR characterizes the nitrate and
chloride plumes with the data collected from existing and new monitoring wells at the Mill. The
investigation concludes that the nitrate and chloride appear to originate from the same source,
which is upgradient of the Mill property more than 1.2 miles from the Mill facilities and was not
caused by or contributed to in any manner by Mill activities. In the October 5, 2010 DRC
NOTICE of Additional Required Action (“NOTICE”), DRC determined that the 2009 CIR is
incomplete, and considered the conclusion regarding the sole source of the nitrogen
contamination to be unsubstantiated with direct and reliable evidence. Furthermore, the
NOTICE stated that DUSA has additionally identified several on-site sources which have a
likelihood of being contributors to the contamination and have yet to be fully examined.
Beginning with the third quarter of 2009, DUSA performed quarterly sampling and analysis of
the new nitrate wells.
1.2 Project Description
1.2.1 Project Objectives
The purpose of this nitrate investigation is to quantify nitrate and chloride in the alluvial soil
column in selected locations at the Site with the following goals:

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1. To establish background concentrations of nitrate and chloride in the alluvial soil in the
vicinity of the Mill.
2. To use the data generated by this investigation to test the “new theory” hypothesis that the
nitrate contamination source is or could be caused by naturally occurring nitrate and
chloride salt deposits located in the vadose zone near or beneath the Mill Site, which have
been mobilized by natural and/or artificial recharge (Walvoord, et al., 2003; Scanlon, et al.,
2005; and others).
3. To use the data to test hypotheses regarding to what extent Mill-related sources
contributed, if at all, to the groundwater nitrate plume.
4. To use the data to test hypotheses regarding to what extent present or historic non-Mill-
related sources contributed, if at all, to the groundwater nitrate plume.
The nitrate investigation has been divided into five phases which are described in detail in
Section 3.0.
1.2.2 Project Measurements
Project measurements will include laboratory analysis of groundwater, soil, and rock chemistry,
and Unified Soil Classification System (“USCS”) soil type classification made at the time of
collection by visual-manual inspection as described in the Standard Practice for Description and
Identification of Soils (Visual-Manual Procedure) ASTM D 2488 – 09a (ASTM, 2009). Note
that the classifications presented in ASTM D 2488 – 09a are identical to the classifications
presented in the Standard Practice for Classification of Soils for Engineering Purposes (Unified
Soil Classification System) ASTM D 2487 – 10 (ASTM, 2010), but are derived from field
observations rather than laboratory analysis. Rock core logging conventions, handling, sample
preparation, and curating will be completed using best field judgment of a Utah State
Professional Geologist, INTERA’s Standard Operating Procedure (SOP) 11 – Rotary Drilling
and Coring, and the U.S. Bureau of Reclamation’s Engineering Geology Field Manual, Chapter
10, pages 276-287, as appropriate (Appendix A). Groundwater, soil, and rock samples will be
submitted to the contract analytical laboratory (“Analytical Laboratory”) for analysis of the
analytes specified in each of the activity-specific documents. The bedrock core analyses
completed in Phase 3 of the investigation will be analyzed using the Synthetic Precipitation
Leaching Procedure (“SPLP”) using U.S. Environmental Protection agency (“EPA”) Method
1312. Method 1312 will produce a leachate which will be analyzed for nitrate, chloride and
sulfate, and ammonium using EPA Method 353.2, EPA Method 300.0, and EPA Method 350.1,
respectively.

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1.3 Quality Objectives
Specific quality objectives have been established for each of the data assessment parameters
identified. These objectives are expressed as quantitative and qualitative statements concerning
the type of data needed to support a decision, based on a specified level of uncertainty. The
criteria (predetermined acceptance limits) are expressed as numerical values for laboratory
analyses and field tests identified. Further discussion of the deep bedrock core sampling for each
parameter and the rationale for its use is presented below.
1.3.1 Precision
Precision is defined as the measure of variability that exists between individual sample
measurements of the same property under identical conditions. Precision is measured through the
analysis of samples containing identical concentrations of the parameters of concern. For
duplicate measurements, precision is expressed as the relative percent difference (“RPD”) of a
data pair and will be calculated by the following equation:
RPD = [(A-B)/{(A+B) /2}] x 100
Where A (original) and B (duplicate) are the reported concentrations for field duplicate sample
analyses (or, in the case of analyses performed by the Analytical Laboratory, the percent
recoveries for matrix spike and matrix spike duplicate samples) (EPA, 1994a, SW-846, Chapter
1, Section 5.0, page 28).
1.3.2 Accuracy
Accuracy is defined as a measure of bias in a system or as the degree of agreement between a
measured value and a known value. The accuracy of laboratory analyses is evaluated based on
analyzing standards of known concentration both before and during analysis. Accuracy will be
evaluated by the following equation (EPA, 1994a, SW-846, Chapter 1, Section 5.0, page 24):
% Recovery = (│A-B│/C) x 100
Where:
A = the concentration of analyte in a sample
B = the concentration of analyte in an unspiked sample
C = the concentration of spike added
1.3.3 Representativeness
Representativeness is defined as the degree to which a set of data accurately represents the
characteristics of a population, parameter, conditions at a sampling point, or an environmental

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condition. Representativeness is controlled by performing all sampling in compliance with this
work plan.
1.3.4 Completeness
Completeness refers to the amount of valid data obtained from a measurement system in
reference to the amount that could be obtained under ideal conditions. Laboratory completeness
is a measure of the number of samples submitted for analysis compared to the number of
analyses found acceptable after review of the analytical data. Completeness will be calculated by
the following equation:
Completeness = (Number of valid data points/total number of measurements) x 100
Where the number of valid data points is the total number of valid analytical measurements
based on the precision, accuracy, and holding time evaluation.
Completeness is determined at the conclusion of the data validation.
1.3.5 Comparability
Comparability expresses the confidence with which one data set can be compared with another.
Comparability of data will be achieved by consistently following standard field and laboratory
procedures and by using standard measurement units to report analytical data.
1.3.6 Detection and Quantitation Limits
The method detection limit (“MDL”) is the minimum concentration of an analyte that can be
reliably distinguished from background for a specific analytical method. The quantitation limit
represents the lowest concentration of an analyte that can be accurately and reproducibly
quantified in a sample matrix. Project-required reporting limits are minimum quantitation limits
for specific analytical methods and sample matrices that are typically several times the MDL to
allow for matrix effects.
1.4 Project Organization
1.4.1 Functional Groups
This work plan specifies roles for a Quality Assurance (“QA”) Manager as well as
representatives of three different functional groups: the data requestors/users, the data generators,
and the data reviewers/approvers. The roles and responsibilities of these representatives are
described below.

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1.4.2 Overall Responsibility for the QA/QC Program
The overall responsibility for ensuring that the Quality Assurance/Quality Control (“QA/QC”)
measures are properly employed is the responsibility of the QA Manager. The QA Manager is
typically not directly involved in the data generation (i.e., sampling or analysis) activities. The
QA Manager is a qualified person designated by DUSA corporate management.
1.4.3 Data Requestors/Users
The generation of data that meets the objectives of this work plan is necessary for management
to make informed decisions to quantify nitrate and chloride in the bedrock in selected locations
at the Site. The data generated by this investigation will be used to test hypotheses regarding
potential sources of nitrate and chloride contamination, including naturally occurring sources.
Accordingly, the data requestors/users (the “Data Users”) are DUSA’s corporate management
and regulatory authorities. The data quality objectives (“DQOs”) required for any sampling
event, such as acceptable minimum detection limits, are specified in this work plan.
1.4.4 Data Generators
The individuals who carry out the sampling and analysis activities at the request of the Data
Users are the data generators. Field sampling activities, QA/QC activities, record keeping, and
chain-of-custody (“COC”) activities are conducted by one or more sampling and quality control
(“QC”)/data monitors (each a “Sampling and QC Monitor”) in accordance with this work plan.
Data generation at the Analytical Laboratory utilized by the Mill to analyze the environmental
samples is performed by or under an employee or agent (the “Analysis Monitor”) of the
Analytical Laboratory, in accordance with the specific requirements of the Analytical
Laboratory’s own QA/QC program.
The responsibilities of the data generators are outlined below.
1.4.4.1 Sampling and QC Monitors
The Sampling and QC Monitors are responsible for field activities. These include:
a. Ensuring that samples are collected, preserved, and transported as specified in the work
plan.
b. Checking that all sample documentation (labels, field data worksheets, COC records,
packing lists) is correct and transmitting that information, along with the samples, to the
Analytical Laboratory in accordance with this work plan.
c. Maintaining records of all samples, tracking those samples through subsequent
processing and analysis, and, where applicable, appropriately disposing of those samples
at the conclusion of the program.

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d. Preparing QC samples for field sample collection during the sampling event.
e. Preparing QC and sample data for review by the QA Manager.
f. Preparing QC and sample data for reporting and entry into a computer data base, where
appropriate.
INTERA Incorporated’s (“INTERA’s”) field manager, Rob Sengebush, will serve as Sampling
and QC Monitor for Phase 3.
1.4.4.2 Analysis Monitor
The Analysis Monitor is responsible for QA/QC activities at the Analytical Laboratory. These
include:
a. Training and qualifying personnel in specified Analytical Laboratory QC and analytical
procedures prior to receiving samples.
b. Receiving samples from the field and verifying that incoming samples correspond to the
packing list or COC sheet.
c. Verifying that Analytical Laboratory QC and analytical procedures meet the Analytical
Laboratory’s QA/QC program, and are in accordance with the requirements for
maintaining National Environmental Laboratory Accreditation Program (“NELAP”)
and/or National Voluntary Laboratory Accreditation Program (“NAVLAP”) certification.
1.4.4.3 Data Reviewers/Approvers
The QA Manager has broad authority to approve or disapprove project plans, specific analyses,
and final reports. In general, the QA Manager is responsible for reviewing and advising on all
aspects of QA/QC, including:
a. Ensuring that the data produced by the data generators meet the specifications set out in
this work plan.
b. Making on-site evaluations and submitting audit samples to assist in reviewing QA/QC
procedures.
c. Determining (with the Sampling and QC Monitor and Analysis Monitor) appropriate
sampling equipment and sample containers, in accordance with this work plan, to
minimize contamination.
d. Supervising all QA/QC measures to assure proper adherence to this work plan and
determining corrective measures to be taken when deviations from this work plan occur.

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The QA Manager may delegate certain of these responsibilities to one or more Sampling and QC
Monitors or to other qualified personnel.
1.5 Special Training and Certification
All soil and rock core logging will be overseen or conducted by a State of Utah Certified
Professional Geologist (“PG”), using the ASTM D 2488 – 09a Standard Practice for Description
and Identification of Soils (Visual-Manual Procedure) (ASTM, 2009), INTERA’s SOP 11 –
Rotary Drilling and Coring, and the U.S. Bureau of Reclamation’s Engineering Geology Field
Manual, Chapter 10, pages 276-287, as appropriate (Appendix A).
Site-specific training for all field personnel will be completed as required by Mill procedures and
will be conducted by Mill personnel.
1.6 Documents and Records
1.6.1 Field Documentation
Field documentation will consist of, but not be limited to, detailed field note books, COC forms,
and digital photographs. In addition, the locations of borings and other field activities will be
recorded using a hand-held global positioning system (“GPS”) instrument. Soil and rock core
logging and details from the boring such as sampling intervals and sample location will be
recorded on a field boring log. Information from the field boring log will be used to create a final
boring log. Copies of these forms are included in Appendix B. Completed forms will be included
in the report. DRC requested the use of a boring log that matched WMMW-16. The log that will
be used is located in Appendix B and contains the same relevant information fields. The boring
log form does not include gamma or neutron logging fields or well completion fields, since those
elements are not part of this investigation.
1.6.2 Reports Generated
Upon completion of the field work and laboratory analysis, a Report describing the results and
the results of the QA/QC checks will be generated and submitted to the DRC.

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2.0 CONCEPTUAL SITE MODEL
This CSM follows the ASTM E1689-95(2003)e1 Standard Guide for Developing Conceptual Site
Models for Contaminated Sites (Appendix C).
2.1 Site Summary
DUSA’s White Mesa property hosts an active uranium mill that is currently processing uranium
ore. Concentrations of nitrate as nitrogen have exceeded the State of Utah’s water quality
standard of 10 mg/L in certain monitoring wells at the Mill Site. Typically, samples from wells
that have exceeded the nitrate standard also have higher concentrations of chloride than samples
from other wells at the Site.
2.2 Site Description
The purpose of this section is to identify the constituents of concern, establish background
concentrations of those constituents, discuss potential source locations (including decisions and
data needs for determining if a source is viable or can and should be eliminated), and discuss
timing and duration of events required to account for the constituent mass observed in
groundwater.
2.2.1 Identify Contaminants
DUSA received a Request for Voluntary Plan and Schedule to Investigate and Remediate Nitrate
Contamination at the White Mesa Mill Site, near Blanding, Utah. The Request was dated
September 30, 2008, and was received from the Co-Executive Secretary of the Utah Water
Quality Board, of the UDEQ. In the Request, the Co-Executive Secretary noted that groundwater
nitrate levels have exceeded the State water quality standard of 10 mg/L in certain monitoring
wells at the Mill Site. Figure 1 is a regional map showing the location of the Mill Site.
Subsequently, in a letter dated December 1, 2009, UDEQ noted that elevated chloride
concentrations exist, apparently coincident with elevated nitrate concentrations. Therefore,
nitrate and chloride are considered to be constituents of concern for this investigation. Table 2
presents the first quarter 2011 chloride and nitrate concentrations in groundwater.
2.2.2 Establishing Background Concentrations of Contaminants
Installation of 19 new monitoring wells has allowed the nitrate and chloride plumes to be fully
bounded at the Site (Figures 2 and 3). On Figure 2, nitrate iso-contours start at 5 mg/L because
that value appears to separate the plume from background. However, as evident from Figure 2,
the 10 mg/L contour that defines the groundwater compliance limit for nitrate at a number of
wells at the Site as specified in GWDP No. UGW370004 is completely closed and defined at the

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Site. Per discussions with UDEQ, the nitrate plume is considered to have been bounded when the
concentrations of nitrate in monitoring wells upgradient, downgradient, and in both crossgradient
directions are less than 10 mg/L. There is no groundwater standard for chloride, but the iso-
contours start at 100 mg/L because that value appears to separate the plume from background.
A feature of the plume maps is that the nitrate (Figure 2) and chloride plumes (Figure 3) are co-
located geographically. Almost all locations that have elevated nitrate concentrations also have
elevated chloride concentrations, implying that the nitrate and chloride impacts to groundwater
had the same source. However, the nitrate plume shows a lobe extending to the southeast
coincident with the chloroform plume (Figure 4), but the chloride plume does not. This indicates
that elevated nitrate was present in the chloroform plume but chloride was not. The chloride
plume demonstrates that there are two distinct plumes, a nitrate-chloride plume and a chloroform
plume, which have distinctly different sources.
2.2.3 Source Locations, Boundaries, and Volumes
Potential on-site sources of nitrate and chloride addressed in the CIR (INTERA, 2009) include:
• The septic leach fields at the Mill Site.
• The municipal sewage plant discharge water used historically as Mill water makeup.
• Livestock activities at the wildlife ponds.
• Livestock activities at the Historical Pond.
• Agricultural activities.
• The former Fly Ash Pond.
• Potential historical spills of ammonium-bearing and/or chloride-bearing process
chemicals.
• A potential breach in the Mill circuit floor drains or tailings transfer lines.
• A potential leak in the Mill’s tailings cells.1
Subsequent to publication of the CIR, other potential sources have been identified. One potential
source is a natural nitrate reservoir. Such concentrations or “reservoirs” of nitrate and chloride
have been identified in the scientific literature (Walvoord, et al., 2003; Scanlon, et al., 2005; and
others).
1 Based on extensive analysis in the background report, age dating of the groundwater reported in the University of
Utah Report (Hurst and Solomon, 2008), mass balance analysis in the original CIR, and the fact that the presence of the nitrate plume is upgradient, the tailings cells are not considered a potential source and will not be studied
specifically in Phases 1 through 5.

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Unsaturated-zone chloride and nitrate profiles archive changes in recharge
related to recent conversion of rangeland to agricultural ecosystems. Increased
recharge associated with dryland as well as irrigated agriculture can lead to
degradation of groundwater quality because of leaching of salts that have been
accumulating in the unsaturated zone for thousands of years prior to cultivation,
because of application of fertilizers, and, in irrigated areas, because of evapo-
concentration of applied groundwater. In the SHP (southern high plains), median
groundwater nitrate-N concentrations increased by 221% beneath irrigated areas
and 163% beneath dryland areas, reflecting LU/LC-induced (land use/land cover)
contamination of groundwater. (Scanlon, et al., 2005).
A second potential source that has been identified is military use of the Mill Site as part of the
Blanding Pershing Missile Launch Complex. Pershing missiles were tested by launching them
from the Blanding site to a target at the White Sands, New Mexico, Missile Base. The Blanding
operation was described as a “shoot and scoot” operation in which mobile launch vehicles would
deploy to Black Mesa, adjacent to the White Mesa Bivouac site, fire their missiles and “scoot”
back to the bivouac site. One possible scenario that may have resulted in nitrate and chloride
contamination at White Mesa is as follows:
• The missile firing at Black Mesa caused clouds of oxidized constituents from burning of
rocket motors to “exhaust” on the launch vehicles.
• Launch vehicles “scooted” back to White Mesa where they needed to be cleaned prior to
the next launch.
• The military required a water source with which to clean the launch vehicles and several
ponds were available at the White Mesa Site (notably, the Historical Pond, which was
highly developed at the time – see 1968 aerial photograph with nitrate plume overlain
[Figure 5]).
• Cleaning the launch vehicles involved washing them with pond water and letting that
water drain directly to the soil near the pond where it infiltrated to groundwater, or
returning it to the pond or other containment where it infiltrated to groundwater.
2.2.4 Time of Initiation, Duration, and Rate of Contaminant Release
Any potential source of nitrate and chloride must meet three necessary conditions to have caused
the mass of nitrate and chloride observed in the groundwater plume beneath the Mill Site. First,
the potential source must have a means to reach groundwater, such as sufficient water or other
fluid to travel through the vadose zone. Second, there must have been sufficient nitrate and
chloride in the source to account for the nitrate and chloride mass observed in the groundwater.

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Third, there must have been sufficient time to travel from the source through the vadose zone
and then downgradient in groundwater to account for the current distribution of the
nitrate/chloride plume.
Travel times through the vadose zone depend on the amount of head available to drive them, but
have been calculated to be on the order of 18-20 feet per year (“ft/yr”) for a pond-like source that
maintains a constant head (HGC, 2009). Thus, it would take approximately two to three years for
nitrate and chloride from a pond-like source to reach groundwater, assuming groundwater is 40-
60 feet below ground surface (“bgs”).
Perched zone pore velocities beneath and immediately upgradient of the tailings cells were
calculated in HGC (2005), based on data from wells MW-23, MW-25, MW-27, MW-28,
MW-29, MW-30, MW-31, MW-32, TW4-20, TW4-21, and TW4-22. Estimated hydraulic
conductivities range from approximately 2x10-7 to 1 x 10-4 centimeters/second (“cm/s”) and yield
a geometric average of approximately 3x10-5 cm/s or 31 ft/yr. Using hydraulic gradients in the
vicinity of each well, the estimated conductivity at each well, and an effective porosity of 0.18,
the estimated pore velocities ranged from 49.5 ft/yr at TW4-21, to 0.010 ft/yr at MW-23, and
have a geometric average of approximately 4.5 ft/yr. Hydraulic gradients in the vicinity of most
of these wells have not changed significantly since 2005, nor have the estimated pore velocities.
The current locus of highest nitrate concentrations in the plume is monitor well TWN-2,
approximately 2,850 feet upgradient of monitor well MW-31 where nitrate concentrations have
been stable since sampling began at that location in 2005. The average nitrate concentration in
samples from MW-31 is 23 mg/L with a standard deviation of 3 mg/L. Assuming that 1) the
highest of the estimated range of pore velocities (49.5 ft/yr) is representative, 2) the nitrate
between TWN-2 and MW-31 resulted from a single source, and 3) no significant spreading or
retardation of seepage occurred in the vadose zone, it would have taken a minimum of 57 years
for nitrate to travel from TWN-2 to MW-31 in groundwater. If the Historical Pond had
maintained a higher gradient in the vicinity of TWN-2 as was likely (see Figure 5 – current
nitrate plume and wells overlain on 1968 aerial photograph), travel times may have been
somewhat faster. However, the White Mesa Mill has been present at the Mill Site for only 31
years and there has been no pond at that location since then.
2.3 Migration Pathway Descriptions
A migration pathway is defined as the course through which contaminants in the environment
may move away from the source(s) to potential environmental receptors, creating a potential
exposure pathway. An exposure pathway is incomplete if any of the following elements are
missing: 1) a mechanism of contaminant release from primary or secondary sources, 2) a

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transport medium if potential environmental receptors are not located at the source, and 3) a
point of potential contact of environmental receptors with the contaminated medium. As
discussed in Section 2.4, for the Mill nitrate and chloride, there is no contact with human or
ecological receptors.
Thirty-two (32) potential sources were identified in Section 2.3.3.1. Due to the large number of
potential sources, similar sources will be grouped together for purposes of discussion. The first
group consists of potential process-related sources such as on-site leach fields, Mill circuit
sources, and chemical storage facilities. The second group contains ponds and pond-like features
including disturbances observed on aerial photographs near far-upgradient and far-downgradient
wells that contain elevated nitrate and chloride. This second group of sources also includes the
locations of potential impact by military or agricultural uses of the Mill Site, described above.
The third group of sources is related to the possibility that a natural nitrate reservoir existed in
the vadose zone across the Mill Site prior to modern land use and that the change in land use
mobilized that vadose zone reservoir and transported it to groundwater.
Figure 6 is a map showing the location of structural cross sections across the Mill Site. Figures 7
through 9 are structural cross sections with the locations of potential sources plotted on them.
Note that the vertical exaggeration of the cross sections ranges from 3:1 to 20:1, which magnifies
the apparent slopes of the contacts depicted in the diagrams. Figure 10 is a wire frame diagram of
the elevation of the bedrock surface beneath the alluvium, the distribution and thickness of the
Mancos Shale at the Site, and the location of structural cross sections. The distribution of the
Mancos shown in Figure 10 coincides with the area(s) where the Mancos is estimated to be at
least 5 feet thick. Figure 11 is an isopach map showing the thickness of the Mancos Shale with
potential nitrate sources overlain. Figures 12 through 15 are schematic diagrams depicting
pathways for each group of sources. There are two schematic diagrams for potential process-
related sources, one depicting a thick section of Mancos Shale beneath the source and one
depicting a thin section, due to the importance of that low permeability unit in the time and or
pathway from the surface to groundwater.
Figures 10 and 11 show a paleoridge of Mancos Shale in the vicinity of the Mill Site that would
presumably impact seepage from potential sources in two ways: 1) the thicker the Mancos, the
slower the expected average rate of downward movement due to the relatively low permeability
of the Mancos, and the greater the potential for lateral spreading; and 2) the steeper the slope of
the alluvium/Mancos contact, the greater the potential for deflection of seepage downslope.
Furthermore, should a mound develop beneath a seepage source, lateral flow from the center of
the mound could cause seepage to move laterally in all directions including upslope. With regard
to the potential for downslope movement at the margins of the Mancos paleoridge, seepage from

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potential process-related sources such as the scale house leach field, may move in an easterly or
southerly direction when it encounters the alluvial-Mancos interface, whereas seepage from
potential process-related sources such as the SAG leach field on the other side of the paleoridge
may be constrained to move in a westerly direction. Note that the thickness of the Mancos Shale
beneath the location of the western half of the Historical Pond is less than 5 feet and is not
expected to be a significant barrier.
Although the slope of the Mancos surface and the thickness of the Mancos are expected to
influence potential seepage as discussed above, the Mancos does not appear to have significantly
impacted chloroform seepage from either the abandoned scale house leach field or from the
former office leach field. Chloroform migration rates based on hydraulic conductivity
measurements in the Burro Canyon Formation south of the abandoned scale house leach field are
consistent with relatively minor retardation of seepage in the vadose zone even though the
Mancos is relatively thick in this area. Furthermore, the abandoned scale house leach field
straddles the bedrock paleoridge suggesting that chloroform should have been diverted to the
east or to the southwest away from the axis of the ridge if the ridge had exerted a significant
influence. However, chloroform from this former source moved primarily south to MW-4 in the
direction of the historic perched groundwater hydraulic gradient. Currently wells TW4-18, TW4-5,
TW4-9, and TW4-3, located south of the abandoned scale house leach field, are outside the
chloroform plume. Prior to 2002, all of these wells except TW4-9 were within the plume at one
time or another. This indicates that prior to 2002, chloroform migration within the Burro Canyon
Formation in this area was primarily to the south. In addition, if chloroform seepage had been
diverted southwest along the slope of the bedrock surface, it is likely that the plume would have
reached TW4-10 sooner than shown by the data. The past and current distributions of chloroform
near the abandoned scale house leach field appear to be more a function of changing hydraulic
gradients and flow directions due to seepage from the wildlife ponds, the permeability
distribution of the Dakota Sandstone/Burro Canyon Formation, and chloroform pumping.
With regard to the former office leach field, chloroform has migrated to the northeast toward
TW4-21, which is upslope with respect to the Mancos paleoridge. This behavior is more
consistent with the presence of a former perched water mound that caused chloroform to move in
all directions away from the leach field source area rather than with diversion along the bedrock
slope.
The behavior of chloroform originating from former leach field source areas suggests that
Mancos surface topology and/or thickness may or may not exert a significant influence on
seepage from potential nitrate sources.

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Once seepage migrates into the Dakota Sandstone/Burro Canyon Formation, the relatively thin,
sub-horizontal, discontinuous, interbedded shale and conglomeratic zones depicted in the cross
sections are expected to exert some influence on the movement of the seepage. The impact of the
interbedded shales is expected to be retardation and lateral spreading of seepage because of the
relatively low permeability of the shales. The impact of the interbedded conglomeratic zones is
expected to be mainly lateral spreading of the seepage. Hydraulic testing at the Mill Site
indicates that conglomeratic zones may or may not have higher permeability than surrounding
sandstones, and suggests that the degree of cementation is an important control in the
permeability of these materials. Overall, the Mancos Shale, where thicker than about 5 feet, is
expected to exert more influence on seepage than the sub-horizontal, relatively thin and
discontinuous shale and conglomeratic zones present in the Dakota Sandstone and Burro Canyon
Formations. However, as discussed above, the Mancos appears to have had minimal impact on
chloroform in seepage originating from the abandoned scale house and former office leach fields,
suggesting that its impact may be similarly small on seepage from potential nitrate sources.
2.3.1 Soil and Bedrock
Assuming that the nitrate and chloride sources originated at the ground surface or within the
alluvial soil (natural nitrate reservoir), alluvial soils and bedrock at the Mill Site would be a
potential pathway for contaminant migration. A soil and bedrock investigation is ongoing in
Phases 1 and 3 of this investigation and early indications are that there is a nitrate and chloride
presence connected with this source.
2.3.2 Groundwater
Groundwater flow at the Mill Site is generally to the southwest toward discharge points such as
Ruin Springs. Groundwater is a potential pathway for contaminant migration. It has been
estimated that travel times between the downgradient edge of Tailings Impoundment 3 and Ruin
Spring (the nearest location of a potential receptor), a distance of 10,000 feet, would be between
3,300 to 14,000 years.
2.3.3 Specific Source Locations and Data Needs
This section evaluates each potential source location or feature and states the hypothesis that
describes the potential pathway to groundwater that might cause observed concentrations of
nitrate and chloride in groundwater. The decision that is required to determine whether any
hypothesis is correct is stated explicitly. Data needs, data gaps, and data that will be collected for
each potential source are also described. For the purpose of developing the logic diagrams
(Figures 16-19) and the CSM diagram (Figure 20), potential source locations can be classified by
type: potential mill-process-related sources, potential pond-related sources (Fly Ash Pond,

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Historical Pond, wildlife pond, Lawzy Lake, and other pond-like sources), and the potential
natural nitrate/chloride reservoir source. Please refer to the logic diagrams and the CSM for each
group of sources.
The following section will discuss each source and the decision criteria. The terms as defined
below are used in the discussions in Section 2.3.3.1.
1. Hydrogeologic Study
DUSA will perform a hydrogeologic evaluation (the “Hydrogeologic Evaluation”) of each
potential source to determine if any potential contamination from the potential source could have
contributed to the plume. The Hydrogeologic Evaluation will evaluate the vertical permeability
of soil and bedrock beneath the surface area from available lithologic logs of soil and bedrock
(including logs from Phase 1 and Phase 3 activities). The Hydrogeologic Evaluation will also
evaluate the permeabilities within the perched aquifer and rates of groundwater movement in that
aquifer between each potential source to the upgradient and downgradient edges of the plume, as
appropriate, based on existing permeability information. To the extent data is available, the
Hydrogeologic Evaluation will also consider elevations of the alluvial/bedrock interface and
other geologic information if appropriate. The Hydrogeologic Evaluation will be submitted to
the Executive Secretary for review and comment on or before December 17, 2011.
2. Isotopic Analysis
Phase 4 of the investigation contemplates the performance of a stable isotope analysis of
groundwater, with details to be provided later, and Phase 5 contemplates the performance of
isotopic soil sampling and analysis, if needed. These Phase 4 and Phase 5 analyses, which may
include age dating of water, are referred to in this work plan as the “Isotopic Analysis.” The
purpose of the Isotopic Analysis is to determine the isotopic fingerprint (the “Isotopic
Fingerprint”) of the plume and of each source, if required. Each Isotopic Fingerprint may be
based in part on stable isotope analyses and in part on age dating of water. The details of the
Isotopic Analysis and the factors to be considered in developing each Isotopic Fingerprint will be
determined, in connection with the review and Executive Secretary approval of more specific
plans for Phase 4 and Phase 5, which will be submitted at later dates. The terms “statistically
comparable” and “uniquely identifiable” will be defined in the QAPs for these phases.
3. Weight of Evidence
In those circumstances where a potential source cannot be dismissed as not contributing to the
plume or included as contributing to the plume based on definitive criteria specified in Section
2.3.3.1, it will be necessary to make a determination whether or not to dismiss or include the

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potential source based on the existing weight of evidence (the “Weight of Evidence”). For the
purposes of this work plan, a Weight of Evidence analysis means an analysis that weighs the
preponderance of all relevant available information to arrive at a decision. It is expected that
such an analysis will involve evaluating several different lines of evidence, each of which may
not be conclusive by itself in arriving at the decision, but which together can lead to the decision.
4. Potential and Possible Sources
In the discussion in Section 2.3.3.1 below, all sources to be evaluated under this work plan are
referred to as “potential sources.” Potential sources that cannot be definitively rejected or
included based on the criteria in Section 2.3.3.1, and which must undergo a Weight of Evidence
analysis, are referred to in Section 2.3.3.1 as “possible sources.”
2.3.3.1 Potential Nitrate/Chloride Source Locations
Potential Nitrate Source Locations:
1. Main leach field (also known as leach field east of scale house, 1985 to present)
2. Sewage vault/lift station (currently active)
3. Scale house leach field, (also known as leach field south of scale house, 1977-1979)
4. Former office leach field
5. Ammonia tanks
6. SAG leach field (leach field north of Mill building, 1998 to 2009)
7. Cell 1 leach field (leach field east of Cell #1, up to 1985)
8. Fly Ash Pond
9. Sodium chlorate tanks (as a potential chloride source)
10. Ammonium sulfate crystal tanks
11. Lawzy sump
12. Lawzy Lake
13. Former vault/lift station (to former office leach field, 1992 to 2009)
14. Truck shop leach field (1979-1985)
15. New Counter Current Decant/Solvent Extraction (“CCD/SX”) leach field (currently
active)
16. Historical Pond (two hypotheses, 16-1 and 16-2)

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17. Wildlife pond (two hypotheses, 17-1 and 17-2)
18. CCD (included inadvertently and eliminated as discussed below)
19. YC Precip Mini-Lab
20. V2O5 Mini-Lab & V2O5 Precip (two hypotheses, 20-1 and 20-2)
21. SX Mini-Lab
22. Chem Lab
23. Met Lab
24. V2O5 oxidation tanks (two hypotheses, 24-1 and 24-2)
25. Natural nitrate reservoir
26. – 32. Other ponds or pond-like sources
1. Main leach field (also known as leach field east of scale house, 1985 to present)
Hypothesis 1: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The main leach field is more than 1,800 feet south of the upgradient
boundary of the main nitrate and chloride plumes. Further, this potential source is cross
gradient to the plumes.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1985) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background as defined in section 3.3.1, perform a hydrogeologic evaluation to determine if
this potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background as
defined in section 3.3.1, proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 27 August 18, 2011
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2. Sewage vault/lift station (currently active)
Hypothesis 2: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: This potential source is more than 1,900 feet downgradient of the
upgradient boundary of the main plume. Therefore it is unlikely that this source could be a
major contributor to the nitrate and chloride plumes.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach groundwater, and if so, to reach the plume?
If this potential source could have contributed to the plume, is the Isotopic Fingerprint
statistically comparable to the Isotopic Fingerprint of the plume? If the Isotopic
Fingerprint of the potential source is statistically comparable to the Isotopic Fingerprint of
the plume, is it uniquely comparable or does the Weight of Evidence indicate that it
contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background as defined in section 3.3.1, perform a hydrogeologic evaluation to determine if
this potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 28 August 18, 2011
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hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background as
defined in section 3.3.1, proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 29 August 18, 2011
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3. Scale house leach field, (also known as leach field south of scale house, 1977-1979)
Hypothesis 3: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The scale house leach field is approximately 2,000 feet south of the
upgradient boundary of the main nitrate and chloride plumes.. Further, this potential source
is cross gradient to the plumes.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1977) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 30 August 18, 2011
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hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 31 August 18, 2011
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4. Former office leach field
Hypothesis 4: Nitrates and chlorides originating from sewage or process chemicals and/or
laboratory wastes (prior to 1981) may have leached through alluvial soil and bedrock to
groundwater and contributed to the plume.
Known Conditions: This potential source is more than 2,000 feet downgradient of the
upgradient boundary of the main plume. Therefore it is unlikely that this source could be a
major contributor to the nitrate and chloride plumes.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1979) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 32 August 18, 2011
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hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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5. Ammonia tanks
Hypothesis 5: Ammonium may have leaked from the tanks through the alluvial soil and
bedrock to groundwater to the plume and oxidized from ammonia to nitrate. Nitrogen in
the ammonia tanks is solely in the ammonium (NH4+) form. Ammonium cations are
typically strongly retarded in a soil-water system and likely would not travel through the
alluvium and bedrock in the ammonia form. It would have to be converted to the nitrate in
a process above the alluvium or in the near subsurface. Subsequently, there would have to
be a source of water or other fluid (such as a pond) immediately below or adjacent to the
ammonium tanks, and it would have to create sufficient head to drive nitrated water all the
way to groundwater. If this were the case, nitrogen would be detected as the nitrate (not
ammonia) form continuously through the alluvium and the bedrock. The ammonia tanks
are not a source of chloride.
Known Conditions: There is no evidence that there has ever been ponded water in the
vicinity of the ammonia tanks. Further, this feature is more than 1,500 feet downgradient of
the upgradient boundary of the main plume, making it unlikely that this potential source is
a major contributor to the nitrate plume.
Necessary Conditions: a) Is there evidence of nitrate concentration in the vadose zone
beneath this feature? b) Is nitrate present in the alluvium and bedrock cores below this
feature? c) Is there an oxidation source adjacent to or beneath the tanks sufficient to
convert ammonia to nitrate? d) Was there a hydraulic head sufficient to drive nitrate from
the vadose zone to groundwater? e) Did this potential source have sufficient mass to have
contributed measurably to nitrate observed in the plume? f) Has there been sufficient time
since this potential source was put into service (circa 1980) for detectable levels of
constituents from this potential source to reach the plume? Note that there would need to
be sufficient time for any ammonium to be oxidized to nitrate, for nitrate to be transported
to groundwater, and then be transported to the downgradient edge of the plume. And g)
Since this potential source is not associated with any chloride, is there a plausible alternate
source for chloride? If this potential source could have contributed to the plume, is the
Isotopic Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If
the Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Data on the
concentration of nitrate, chloride, ammonium, dissolved oxygen, and oxidation reduction

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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potential in the groundwater beneath this feature. Possible need for Isotopic Analysis Data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Need ammonium and dissolved oxygen from adjacent monitor
wells. Possible need for Isotopic Analysis Data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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6. SAG leach field (leach field north of mill building, 1998 to 2009)
Hypothesis 6: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The SAG leach field is 1,000 feet downgradient of the upgradient
margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1998) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 36 August 18, 2011
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not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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7. Cell 1 leach field (leach field east of Cell #1, 1979 to 1985)
Hypothesis 7: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The cell 1 leach field approximately 1,600 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1979) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 38 August 18, 2011
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not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 39 August 18, 2011
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8. Fly Ash Pond
Hypothesis 8: Nitrates and chlorides associated with coal and coal ash, and potential runoff
from Site processes, could have ponded and may have leached through the alluvial soil and
bedrock to groundwater and contributed to the plume. The pond received coal fly ash,
containing oxidized nitrogen (the nitrate not ammonium form) sporadically from 1980 to
1989. The pond could have potentially received some washwaters containing ammonium
nitrogen from the vanadium circuit from 1980 through the present.
Known Conditions: The Fly Ash Pond is approximately 2,200 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate, and/or ammonium, and chloride
concentrations in the vadose zone beneath this feature? b) If ammonium is present, is there
an oxidation source adjacent to or beneath the tanks sufficient to convert ammonium to
nitrate? c) Was there a hydraulic head sufficient to drive nitrate from the vadose zone to
groundwater? d) Did this potential source have sufficient mass to have contributed
measurably to nitrate and/or chloride observed in the plume? And e) Has there been
sufficient time since this potential source was put into service (circa 1981) for detectable
levels of constituents from this potential source to reach groundwater, and if so, to reach
the plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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9. Sodium chlorate tanks
Hypothesis 9: Chlorides associated with sodium chlorate storage may have leached through
the alluvial soil and bedrock to groundwater and contributed to the plume. If this were an
appreciable source, it would also be associated with measurably elevated sodium in soil
and/or groundwater adjacent to and beneath the tank area. Sodium chlorate is not a source
of nitrogen atoms and has been retained for evaluation as a chloride source.
This is a low priority source, and is inaccessible to drilling and coring. Since it is not a
source of nitrate, it will not be subject to physical investigation and has only been retained
in the list of hypotheses for completeness.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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10. Ammonium sulfate crystal tanks
Hypothesis 10: Ammonium sulfate crystals may have spilled around the ammonium sulfate
crystal tanks. Over time and with rain, the ammonium converts to nitrate and may have
leached through the alluvial soil and bedrock to groundwater and contributed to the plume.
Nitrogen in the ammonium sulfate tanks is solely in the ammonium (NH4+) form.
Ammonium cations are typically strongly retarded in a soil-water system and likely would
not travel through the alluvium and bedrock in the ammonium form. It would have to be
converted to the nitrate from a process above the alluvium or in the near subsurface. That
is, there would have to be a source of oxygenated water or other oxidizing fluid (such as a
pond) immediately below or adjacent to the ammonium sulfate tanks, and it would have to
create sufficient head to drive nitrated water all the way to groundwater. If this were the
case, nitrogen would be detected as the nitrate (not ammonium) form continuously through
the alluvium and the bedrock. The ammonium sulfate tanks are not a source of chloride. A
combination of elevated nitrate and sulfate in the soil adjacent to or beneath the tanks or in
the groundwater near the tanks would support this as a possible source.
Known Conditions: The ammonium sulfate crystal tanks are approximately 1,200 feet
downgradient of the upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate concentration in the vadose zone
beneath this feature? b) Are nitrate and sulfate both elevated in the alluvium and bedrock
cores below this feature? c) Is there an oxidation source adjacent to or beneath the tanks
sufficient to convert ammonium to nitrogen? d) Was there a hydraulic head sufficient to
drive nitrate from the vadose zone to groundwater? e) Did this source have sufficient mass
to have contributed measurably to nitrate observed in the plume? f) Has there been
sufficient time since this source was put into service (circa 1980) for detectable levels of
constituents from this potential source to reach groundwater? Note that there would need
to be sufficient time for any ammonium to be oxidized to nitrate, for nitrate to be
transported to groundwater, and then be transported to the downgradient edge of the plume.
And g) Since this potential source is not associated with any chloride, is there a plausible
alternate source for chloride? If this potential source could have contributed to the plume,
is the Isotopic Fingerprint statistically comparable to the Isotopic Fingerprint of the plume?
If the Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Data on the
concentration of nitrate, chloride, ammonium, dissolved oxygen, and oxidation reduction

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potential in the groundwater beneath this feature. Possible need for Isotopic Analysis data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Need ammonium and dissolved oxygen from adjacent monitor
wells. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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11. Lawzy sump
Hypothesis 11: This unlined sump was used to pump water from Lawzy Lake (which was
filled from the frog pond that may have contained water from the municipal water
treatment plant located north of the Mill) to Mill processes. Nitrate- and chloride-laden
water from the sump may have leached through alluvial soil and bedrock to groundwater
and contributed to the plume. While not always present in soils and groundwater associated
with cattle wastes and byproducts, cryptosporidium is frequently present in livestock and
animal sources, not human or industrial (chemical) sources. If detected along with elevated
nitrate, the presence of cryptosporidium would help to earmark the source of nitrate as
being of livestock/animal origin.
Known Conditions: Lawzy sump is approximately 1,100 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in groundwater? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach the plume? If this potential source could
have contributed to the plume, is the Isotopic Fingerprint statistically comparable to the
Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, ammonium, and
cryptosporidium in the alluvial and bedrock portion of the vadose zone beneath this feature.
Possible need for Isotopic Analysis data. Possible need for Non-Isotopic Groundwater
Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times

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background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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12. Lawzy Lake
Hypothesis 12: Nitrate- and chloride-laden water from Lawzy Lake (which was filled from
the frog pond, which may have contained water from the municipal water treatment plant
located north of the Mill) may have leached through alluvial soil and bedrock to
groundwater and contributed to the plume. While not always present in soils and
groundwater associated with cattle wastes and byproducts, cryptosporidium is frequently
present in livestock and animal sources, not human or industrial (chemical) sources. If
detected along with elevated nitrate, the presence of cryptosporidium would help to
earmark the source of nitrate as being of livestock/animal origin.
Known Conditions: Lawzy Lake is approximately 300 feet upgradient of the upgradient
margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach the plume? If this potential source could
have contributed to the plume, is the Isotopic Fingerprint statistically comparable to the
Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine

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if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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13. Former vault/lift station (to former office leach field, 1992 to 2009)
Hypothesis 13: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The former vault is approximately 1,500 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1992) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is

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not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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14. Truck shop leach field (1979-1985)
Hypothesis 14: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The truck shop leach field is approximately 2,300 feet downgradient of
the upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (1979) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is

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not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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15. New CCD/SX leach field (currently active)
Hypothesis 15: Nitrates and chlorides originating from sewage or process chemicals may
have leached through alluvial soil and bedrock to groundwater and contributed to the
plume.
Known Conditions: The CCD/SX leach field is approximately 1,200 feet downgradient of
the upgradient margin of the main plume. This leach field did not yet exist when the nitrate
plume was identified.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service (2009) for detectable levels
of constituents from this potential source to reach groundwater, and if so, to reach the
plume? If this potential source could have contributed to the plume, is the Isotopic
Fingerprint statistically comparable to the Isotopic Fingerprint of the plume? If the
Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the

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hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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16. Historical Pond
Hypothesis 16-1: The Historical Pond was associated with agriculture and may have been
used as a stock pond or a fertilizer mixing pond, or may have collected fertilizer from
runoff of nearby agricultural land. Nitrate- and chloride-laden water from the Historical
Pond may have leached through the alluvial soil and bedrock to groundwater. While not
always present in soils and groundwater associated with cattle wastes and byproducts,
cryptosporidium is frequently present in livestock and animal sources, not human or
industrial (chemical) sources. If detected along with elevated nitrate, the presence of
cryptosporidium would help to earmark the source of nitrate as being of livestock/animal
origin. Based on anecdotal information (interviews with landowners), the pond area was
one of several areas that may have been used for dumping truckloads of salt for cattle salt
licks. If this is correct, elevated levels of sodium chloride may be present in soil and/or
groundwater in the areas of the Historical Pond. Historical sheep dipping activities may
also have impacted the pond.
Known Conditions: The Historical Pond has been in existence since the 1920’s and has had
sufficient head to infiltrate to groundwater at various times throughout that history. The
source of ponded water and its quality is unknown but the primary purpose of the pond has
been agricultural. Historical aerial imagery from 1968 shows that the Historical Pond at
that time was larger than the current Northern Wildlife Pond, which is responsible for the
current groundwater mound beneath the mill site. The Historical Pond was in place and
full during the time frame that the Blanding Pershing Missile Launch Complex was using
the White Mesa site but was removed before the White Mesa uranium mill began
operations. The Historical Pond was located directly above the upgradient portion of the
uranium and nitrate plumes beneath the mill site and directly above the locus of highest
nitrate concentrations. As stated in Section 2.2.4, travel times in the perched aquifer
suggest that it took a minimum of 57 years for the nitrate and chloride plumes to develop to
their current extent and the Historical Pond is one of the few potential sources that were
present on White Mesa 57 years ago.
Necessary Conditions: a) Is there evidence of nitrate, sodium, or chloride concentrations in
the vadose zone beneath this feature? b) Did this potential source have sufficient mass to
have contributed measurably to nitrate and/or chloride observed in groundwater? c) Does
the hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach groundwater? If this potential source could
have contributed to the plume, is the Isotopic Fingerprint statistically comparable to the
Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is

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statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Sufficient (But Not Necessary) Condition: Is cryptosporidium present in the same media
(soil or groundwater) with elevated levels of nitrate?
Data Needs for Decision: Data on the concentration of nitrate and/or ammonium, sodium,
chloride, and cryptosporidium in the alluvial and bedrock portion of the vadose zone
beneath this feature. Data on concentrations of the same constituents in groundwater.
Possible need for Isotopic Analysis data. Possible need for Non-Isotopic Groundwater
Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, ammonium, sodium, and cryptosporidium concentration
data from the bedrock portion of the vadose zone. Data on the same constituents in
groundwater. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: Collect data on concentrations of chemical constituents in groundwater
that might be associated with agricultural uses of this feature along with cryptosporidium
(Phase 2). If cryptosporidium is present along with elevated nitrate in water or alluvium,
support is provided for an agricultural source.
If the results of Phase 1 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), conduct coring study of bedrock to groundwater (Phase 3).
Analyze bedrock core samples for nitrate, chloride, and ammonium concentration data. If
the results of Phase 3 sampling of the bedrock provide evidence that any of the constituents
(nitrate, chloride, or ammonium) are present above two times background (as defined in
Section 3.3.1), perform a hydrogeologic evaluation to determine if this potential source
could have generated sufficient mass during the time frame required to produce the plume
and if there was a plausible pathway for any potential contamination from this potential
source to have contributed to the plume. If the results of the hydrogeologic evaluation are
negative, the Weight of Evidence suggests that this feature is not a potential source. If the
results of the hydrogeologic evaluation are positive, perform a mass balance to determine
source viability. If the source is viable, move to Phases 4 and 5 Isotopic Fingerprint
analysis of groundwater, alluvial soil, and bedrock core. If the groundwater and potential
source fingerprints match to a reasonable degree, the Weight of Evidence suggests that a
source has been identified. If the mass balance determines that the potential source is not
viable, the Weight of Evidence suggests that a source has not been identified.

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If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this potential
source could have generated sufficient mass during the time frame required to produce the
plume and if there was a plausible pathway for any potential contamination from this
potential source to have contributed to the plume. If the results of the hydrogeologic
evaluation are negative, the Weight of Evidence suggests that this feature is not a potential
source. If the results of the hydrogeologic evaluation are positive, proceed to a mass balance
to determine source viability. If the mass balance determines that the potential source is not
viable, the Weight of Evidence suggests that a source has not been identified. If the mass
balance determines that the potential source is viable, the Weight of Evidence suggests that a
source has been identified.

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Hypothesis 16-2: Historical pond was filled with water from one or more ponds north of
the Mill Site and used by the military during the Pershing Missile Operation at the
Blanding Launch Site (1963-1970) as wash water for equipment used to launch missiles.
Launch equipment may have become coated with nitrate and chloride as oxidized material
from “blow down” rained down on the launch vehicle during missile launch. Aerial
photography of the Site shows that the pond was full of water during the period of military
use, and was dry in a 1973 photo, after the military left the Site. Nitrate- and chloride-
laden water from the Historical Pond may have leached through the alluvial soil and
bedrock to groundwater and contributed to the plume.
Per the current owner of Morton-Thiokol, ATK, the Thiokol Pershing Missile rocket
motors (models Thiokol TX-174 and TX-175) used aluminum fuel with ammonium
perchlorate as an oxygen source. Since ammonium would have been oxidized during the
launch combustion process, if ammonium residuals from Pershing equipment
decontamination reached the pond, the residuals would already have been oxidized to the
nitrate form. Therefore, for this activity to be a nitrate source, an oxidizing environment in
groundwater or the alluvium is not required.
Known Conditions: The Historical Pond has been in existence since the 1920’s and has had
sufficient head to infiltrate to groundwater at various times throughout that history. The
source of ponded water and its quality is unknown but the primary purpose of the pond has
been agricultural. Historical aerial imagery from 1968 shows that the Historical Pond at
that time was larger than the current Northern Wildlife Pond, which is responsible for the
current groundwater mound beneath the mill site. The Historical Pond was in place and
full during the time frame that the Blanding Pershing Missile Launch Complex was using
the White Mesa site but was removed before the White Mesa uranium mill began
operations. The Historical Pond was located directly above the upgradient portion of the
uranium and nitrate plumes beneath the mill site and directly above the locus of highest
nitrate concentrations. As stated in Section 2.2.4, travel times in the perched aquifer
suggest that it took a minimum of 57 years for the nitrate and chloride plumes to develop to
their current extent and the Historical Pond is one of the few potential sources that were
present on White Mesa 57 years ago.
Necessary Conditions: a) Is there evidence of nitrate or ammonium, perchlorate, and/or
aluminum concentrations in the vadose zone beneath this feature? b) Did this potential
source have sufficient mass to have contributed measurably to nitrate and/or chloride
observed in the plume? c) Does the hydrogeology support and explain transport to
groundwater? And d) Has there been sufficient time since this potential source was
possibly used by the Pershing Missile Operation (1963 to 1970) for detectable levels of

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constituents from this activity to reach the plume or for existing constituents in the pond to
reach groundwater by hydraulic head generated during this period? If this potential source
could have contributed to the plume, is the Isotopic Fingerprint statistically comparable to
the Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Gaps: Need nitrate, chloride, aluminum, perchlorate, and ammonium concentration
data from the bedrock portion of the vadose zone. Data on concentrations of the same
constituents in groundwater. Need background concentrations of aluminum in alluvial
soils. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: Perform a hydrogeologic evaluation to determine if any potential
contamination from this potential source could have contributed to the plume. If not, this
potential source is ruled out. If the hydrogeologic analysis is not conclusive, proceed as
follows. If the results of Phase 1 or subsequent sampling of the alluvium provide evidence
that any of the constituents (nitrate, chloride, ammonium, aluminum, or perchlorate) are
present above two times background (as defined in Section 3.3.1), conduct a coring study
of bedrock to groundwater (Phase 3). If aluminum or perchlorate are elevated in alluvium
and/or bedrock, military use is confirmed. Analyze bedrock core samples for concentration
data of those constituents. If none of those constituents are present above two times
background (as defined in Section 3.3.1), this can be eliminated as a potential source. If
any of those constituents are present above two times background (as defined in Section
3.3.1), conduct a mass balance calculation to determine if the concentrations in bedrock are
sufficient to have contributed to nitrate and chloride observed in the plume. If the
concentrations in bedrock are sufficient to have contributed to nitrate and chloride observed
in the plume, conduct an Isotopic Analysis on samples of bedrock core and of groundwater
from the plume (Phase 5). If the Isotopic Fingerprint is uniquely identifiable to the
potential source, then the source has been identified. If the Isotopic Fingerprint of the core
sample is not uniquely identifiable to the potential source but is statistically comparable to
the Isotopic Fingerprint of groundwater from the plume, a possible source has been
identified. If a possible source has been identified, perform a Weight of Evidence analysis
to determine if the possible source has contributed to the plume. If the possible source has
been determined to have contributed to the plume, perform a hydrogeologic and mass
balance analysis to determine to what extent the source has contributed to the plume.

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17. Wildlife pond
Hypothesis 17-1: The wildlife pond was historically filled with water from the frog pond,
which may have contained water from the municipal wastewater treatment facility located
north of the Mill. Nitrate- and chloride-laden water from the wildlife pond may have
leached through the alluvial soil and bedrock to groundwater.
Known Conditions: The wildlife pond is approximately 600 feet upgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach groundwater? If this potential source could
have contributed to the plume, is the Isotopic Fingerprint statistically comparable to the
Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
If the results of Phase 1 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), conduct coring study of bedrock to groundwater (Phase 3).
Analyze bedrock core samples for nitrate, chloride, and ammonium concentration data. If
the results of Phase 3 sampling of the bedrock provide evidence that any of the constituents
(nitrate, chloride, or ammonium) are present above two times background (as defined in
Section 3.3.1), perform a hydrogeologic evaluation to determine if this potential source
could have generated sufficient mass during the time frame required to produce the plume
and if there was a plausible pathway for any potential contamination from this potential
source to have contributed to the plume. If the results of the hydrogeologic evaluation are
negative, the Weight of Evidence suggests that this feature is not a potential source. If the

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results of the hydrogeologic evaluation are positive, perform a mass balance to determine
source viability. If the source is viable, move to Phases 4 and 5 Isotopic Fingerprint
analysis of groundwater, alluvial soil, and bedrock core. If the groundwater and potential
source fingerprints match to a reasonable degree, the Weight of Evidence suggests that a
source has been identified. If the mass balance determines that the potential source is not
viable, the Weight of Evidence suggests that a source has not been identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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Hypothesis 17-2: The wildlife pond was historically associated with agriculture and may
have been used as a stock pond or a fertilizer mixing pond, or may have collected fertilizer
from runoff of nearby agricultural land, or may have been utilized in connection with
historic sheep dipping activities. Nitrate- and chloride-laden water from the wildlife pond
may have leached through the alluvial soil and bedrock to groundwater and contributed to
the plume. It is also possible that military activity could have been associated with the
wildlife pond.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach the plume? If this potential source could
have contributed to the plume, is the Isotopic Fingerprint statistically comparable to the
Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, ammonium, and
cryptosporidium in the alluvial and bedrock portion of the vadose zone beneath this feature.
Data on concentrations of chemical constituents in groundwater that might be associated
with agricultural or military uses of this feature. Possible need for Isotopic Analysis data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Data on concentrations of chemical constituents in
groundwater that might be associated with agricultural or military uses of this feature.
Possible need for Isotopic Analysis data. Possible need for Non-Isotopic Groundwater
Data (for Weight of Evidence analysis).
Decision Process: Collect data on concentrations of chemical constituents in groundwater
that might be associated with agricultural uses of this feature along with cryptosporidium
(Phase 2). If cryptosporidium is present along with elevated nitrate in water or alluvium,
support is provided for an agricultural source.
If the results of Phase 1 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), conduct coring study of bedrock to groundwater (Phase 3).
Analyze bedrock core samples for nitrate, chloride, and ammonium concentration data. If
the results of Phase 3 sampling of the bedrock provide evidence that any of the constituents

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(nitrate, chloride, or ammonium) are present above two times background (as defined in
Section 3.3.1), perform a hydrogeologic evaluation to determine if this potential source
could have generated sufficient mass during the time frame required to produce the plume
and if there was a plausible pathway for any potential contamination from this potential
source to have contributed to the plume. If the results of the hydrogeologic evaluation are
negative, the Weight of Evidence suggests that this feature is not a potential source. If the
results of the hydrogeologic evaluation are positive, perform a mass balance to determine
source viability. If the source is viable, move to Phases 4 and 5 Isotopic Fingerprint
analysis of groundwater, alluvial soil, and bedrock core. If the groundwater and potential
source fingerprints match to a reasonable degree, the Weight of Evidence suggests that a
source has been identified. If the mass balance determines that the potential source is not
viable, the Weight of Evidence suggests that a source has not been identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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18. CCD Circuit
This area was inadvertently added to the Phase 1 Plan. The CCD circuit uses no
chlorinated, ammoniated, or nitrated compounds. The CCD area contains no chlorinated,
ammoniated, or nitrated process solutions. The former sewage vault and current leach field
near the CCD area are addressed as individual sources elsewhere in this section. This area
will not be considered further.

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19. YC Precip Mini-Lab
Hypothesis 19: Ammonium or nitrate-bearing chemicals from the mini-lab may have
spilled or leaked. Ammonium-, nitrate-, or chloride-laden water from the mini-lab may
have leached through the alluvial soil and bedrock to groundwater and contributed to the
plume. The mini-lab areas use very small quantities of reagents and process solutions
which drain either to an above-the-floor bucket or to an in-floor drain sump, which is
pumped back to the process. If this were a source of contamination, there would need to be
evidence of a breach or failure of the building floor or the sump. This potential source is
inaccessible to geoprobe and core drilling equipment and is a low priority due to generally
small amounts of nitrate or chloride that it could possibly have contributed to the plume.
Therefore, no sampling will be conducted at this location.
Known Conditions: The YC Precip Mini-Lab is approximately 1,400 feet downgradient of
the upgradient margin of the main plume.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonium-bearing chemicals or
chloride-bearing chemicals used in this mini-lab and at what time periods? b) Is there
evidence of a failure of the floor sump and/or floor drains? c) Did this potential source have
sufficient mass to have contributed measurably to nitrate and/or chloride observed in the
plume? d) If only ammonium-bearing compounds were used, is there an oxidation source
adjacent to or beneath the mini-lab sufficient to convert ammonium to nitrogen? e) Is there
a hydraulic head sufficient to drive nitrate from the vadose zone to groundwater? And f)
Has there been sufficient time since this potential source was put into service for detectable
levels of constituents from this potential source to reach groundwater? If this potential
source could have contributed to the plume, is the Isotopic Fingerprint statistically
comparable to the Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the
potential source is statistically comparable to the Isotopic Fingerprint of the plume, is it
uniquely comparable or does the Weight of Evidence indicate that it contributed to the
plume?
Data Needs for Decision: Data on the use of ammonium-bearing, nitrate-bearing, and
chloride-bearing compounds in this mini-lab. Information on the condition and history of
the floor, drains, and sumps in the building. Data on the concentration of nitrate, chloride,
ammonium, dissolved oxygen, and oxidation reduction potential in the groundwater
adjacent to this building. Possible need for Isotopic Analysis data. Possible need for Non-
Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need information on the structure and history of the floors and drains. Need
information on chemicals and use rates in the mini-lab. Need nitrate, ammonium, and
dissolved oxygen from adjacent monitor wells. Data on concentrations of nitrate, chloride,

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 65 August 18, 2011
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and ammonium are already available from the groundwater and nitrate monitoring
programs. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: Determine if there has been a failure or breach of the sink, sump, or
collection bucket. If not, this potential source has been eliminated. If not eliminated,
perform a hydrogeologic evaluation to determine if any potential contamination from this
potential source could have contributed to the plume. If not, this potential source is ruled
out. If the hydrogeologic analysis is not conclusive, proceed as follows. If no nitrate-
bearing, ammonium-bearing or chloride-bearing compounds were used in this lab, this
potential source can be eliminated. Is there any evidence of a failure of the building floor
or sumps? If any of these compounds were used, is there an oxidation source adjacent to or
beneath the lab sufficient to convert ammonium to nitrogen, and is there a hydraulic head
sufficient to drive nitrate or chloride from the vadose zone to groundwater? If the answer
to any of these is no, this potential source can be eliminated. If a possible source has been
identified, perform a Weight of Evidence analysis to determine if the possible source has
contributed to the plume. If the possible source has been determined to have contributed to
the plume, perform a hydrogeologic and mass balance analysis to determine to what extent
the source has contributed to the plume.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 66 August 18, 2011
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20. V2O5 Mini-Lab & V2O5 Precip
Hypothesis 20-1: Ammonium or nitrate-bearing chemicals from the mini-lab may have
spilled or leaked. Ammonium-, nitrate-, or chloride-laden water from the lab may have
leached through the alluvial soil and bedrock to groundwater and contributed to the plume.
The mini-lab areas use very small quantities of reagents and process solutions which drain
either to an above-the-floor bucket or to an in-floor drain sump, which is pumped back to
the process. If this were a source of contamination, there would need to be evidence of a
breach or failure of the building floor or the sump.
Known Conditions: The V2O5 mini-lab is 1,300 feet downgradient of the upgradient margin
of the main plume.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonium-bearing chemicals,
or chloride-bearing chemicals used in this mini-lab and at what time periods? a) Is there
evidence of a failure of the floor sump and/or floor drains? b) Did this potential source
have sufficient mass to have contributed measurably to nitrate and/or chloride observed in
the plume? c) If only ammonium-bearing compounds were used, is there an oxidation
source adjacent to or beneath the mini-lab sufficient to convert ammonium to nitrogen? d)
Is there a hydraulic head sufficient to drive nitrate from the vadose zone to groundwater?
And e) Has there been sufficient time since this potential source was put into service for
detectable levels of constituents from this potential source to reach the plume? If this
potential source could have contributed to the plume, is the Isotopic Fingerprint statistically
comparable to the Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the
potential source is statistically comparable to the Isotopic Fingerprint of the plume, is it
uniquely comparable or does the Weight of Evidence indicate that it contributed to the
plume?
Data Needs for Decision: Data on the use of ammonium-bearing, nitrate-bearing, and
chloride-bearing compounds in this mini-lab. Information on the condition and history of
the floor, drains, and sumps in the building. Data on the concentration of nitrate, chloride,
ammonium, dissolved oxygen, and oxidation reduction potential in the groundwater
adjacent to this feature. Possible need for Isotopic Analysis data. Possible need for Non-
Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need information on the structure and history of the floors and drains. Need
information on chemicals and use rates in the mini-lab. Need nitrate, ammonium, and
dissolved oxygen from adjacent monitor wells. Data on concentrations of nitrate, chloride,
and ammonium are already available from the groundwater and nitrate monitoring
programs. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 67 August 18, 2011
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Decision Process: Determine if there has been a failure or breach of the sink, sump, or
collection bucket. If not, this potential source has been eliminated. If not eliminated,
perform a hydrogeologic evaluation to determine if any potential contamination from this
potential source could have contributed to the plume. If not, this potential source is ruled
out. If the hydrogeologic analysis is not conclusive, proceed as follows. If no nitrate-
bearing, ammonium-bearing, or chloride-bearing compounds were used in this mini-lab,
this potential source can be eliminated. If any of these compounds were used, is there an
oxidation source adjacent to or beneath the lab sufficient to convert ammonium to nitrogen,
and is there a hydraulic head sufficient to drive nitrate or chloride from the vadose zone to
groundwater? If the answer to any of these is no, this potential source can be eliminated.
If a possible source has been identified, perform a Weight of Evidence analysis to
determine if the possible source has contributed to the plume. If the possible source has
been determined to have contributed to the plume, perform a hydrogeologic and mass
balance analysis to determine to what extent the source has contributed to the plume.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 68 August 18, 2011
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Hypothesis 20-2: Ammonium sulfate from the mix tanks on the first floor or the precip
tanks on the upper floor may have spilled and leached through the alluvial soil and bedrock
to groundwater. Nitrogen in the ammonium sulfate mix and precip tanks is solely in the
ammonium (NH4+) form. Ammonium cations are typically strongly retarded in a soil-water
system and likely would not travel through the alluvium and bedrock in the ammonium
form. It would have to be converted to the nitrate from a process above the alluvium or in
the near subsurface. That is, there would have to be a source of oxygenated water or other
oxidizing fluid (such as a pond) immediately below or adjacent to the ammonium tanks,
and it would have to create sufficient head to drive nitrated water all the way to
groundwater. If this were the case, nitrogen would be detected as the nitrate (not
ammonium) form continuously through the alluvium and the bedrock. The ammonium
sulfate mix and precip tanks are not a source of chloride.
Necessary Conditions: a) Is there evidence of nitrate concentration in the vadose zone
beneath this feature? b) Is nitrate present in the alluvium and bedrock cores below this
feature? c) Is there an oxidation source adjacent to or beneath the tanks sufficient to
convert ammonium to nitrate? d) Is there a hydraulic head sufficient to drive nitrate from
the vadose zone to groundwater? e) Did this potential source have sufficient mass to have
contributed measurably to nitrate observed in the plume? f) Has there been sufficient time
since this potential source was put into service (circa 1980) for detectable levels of
constituents from this potential source to reach groundwater? Note that there would need
to be sufficient time for any ammonium to be oxidized to nitrate, for nitrate to be
transported to groundwater, and then be transported to the downgradient edge of the plume.
And g) Since this potential source is not associated with any chloride, is there a plausible
alternate source for chloride? If this potential source could have contributed to the plume,
is the Isotopic Fingerprint statistically comparable to the Isotopic Fingerprint of the plume?
If the Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Data on the
concentration of nitrate, chloride, ammonium, dissolved oxygen, and oxidation reduction
potential in the groundwater beneath this feature. Possible need for Isotopic Analysis data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Need ammonium and dissolved oxygen from adjacent monitor

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 69 August 18, 2011
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wells. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: Determine if there has been a failure or breach of the floor or floor drain
sump. If not, this potential source has been eliminated.
If the results of Phase 1 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), conduct coring study of bedrock to groundwater (Phase 3).
Analyze bedrock core samples for nitrate, chloride, and ammonium concentration data. If
the results of Phase 3 sampling of the bedrock provide evidence that any of the constituents
(nitrate, chloride, or ammonium) are present above two times background (as defined in
Section 3.3.1), perform a hydrogeologic evaluation to determine if this potential source
could have generated sufficient mass during the time frame required to produce the plume
and if there was a plausible pathway for any potential contamination from this potential
source to have contributed to the plume. If the results of the hydrogeologic evaluation are
negative, the Weight of Evidence suggests that this feature is not a potential source. If the
results of the hydrogeologic evaluation are positive, perform a mass balance to determine
source viability. If the source is viable, move to Phases 4 and 5 Isotopic Fingerprint
analysis of groundwater, alluvial soil, and bedrock core. If the groundwater and potential
source fingerprints match to a reasonable degree, the Weight of Evidence suggests that a
source has been identified. If the mass balance determines that the potential source is not
viable, the Weight of Evidence suggests that a source has not been identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 70 August 18, 2011
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21. SX Mini-Lab
Hypothesis 21: Ammonium-, nitrate-, or chloride-bearing chemicals from the mini-lab
may have spilled or leaked. Ammonium-, nitrate-, or chloride-laden water from the mini-
lab may have leached through the alluvial soil and bedrock to groundwater and contributed
to the plume. This potential source is inaccessible to geoprobe and core drilling equipment
and is a low priority due to generally small amounts of nitrate that it could possibly have
contributed to the plume. Therefore, no sampling will be conducted at this location. The
mini-lab areas use very small quantities of reagents and process solutions which drain
either to an above-the-floor bucket or to an in-floor drain sump, which is pumped back to
the process. If this were a source of contamination, there would need to be evidence of a
breach or failure of the building floor or the sump.
Known Conditions: The SX Mini-Lab is approximately 1,500 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonium-bearing chemicals,
or chloride-bearing chemicals used in this mini-lab and at what time periods? b) Is there
evidence of a failure of the floor sump and/or floor drains? c) Did this potential source have
sufficient mass to have contributed measurably to nitrate and/or chloride observed in the
plume? d) If only ammonium-bearing compounds were used, is there an oxidation source
adjacent to or beneath the mini-lab sufficient to convert ammonium to nitrogen? e) Is there
a hydraulic head sufficient to drive nitrate from the vadose zone to groundwater? And f)
Has there been sufficient time since this potential source was put into service for detectable
levels of constituents from this potential source to reach the plume? If this potential source
could have contributed to the plume, is the Isotopic Fingerprint statistically comparable to
the Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Needs for Decision: Data on the use of ammonium-bearing, nitrate-bearing, and
chloride-bearing compounds in this mini-lab. Information on the condition and history of
the floor, drains, and sumps in the building. Data on the concentration of nitrate, chloride,
ammonium, dissolved oxygen, and oxidation reduction potential in the groundwater
adjacent to this feature. Possible need for Isotopic Analysis data. Possible need for Non-
Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need information on the structure and history of the floors and drains. Need
information on chemicals and use rates in the mini-lab. Need nitrate, ammonium, and
dissolved oxygen from adjacent monitor wells. Data on concentrations of nitrate, chloride,
and ammonium are already available from the groundwater and nitrate monitoring

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 71 August 18, 2011
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programs. Possible need for Isotopic Analysis data. Possible need for Non-Isotopic
Groundwater Data (for Weight of Evidence analysis).
Decision Process: Determine if there has been a failure or breach of the sink, sump, or
collection bucket. If not, this potential source has been eliminated. If not eliminated,
perform a hydrogeologic evaluation to determine if any potential contamination from this
potential source could have contributed to the plume. If not, this potential source is ruled
out. If the hydrogeologic analysis is not conclusive, proceed as follows. If no nitrate-
bearing, ammonium-bearing, or chloride-bearing compounds were used in this lab, this
source can be eliminated. Is there any evidence of a failure of the building floor or sumps?
If any of these compounds were used, is there an oxidation source adjacent to or beneath
the lab sufficient to convert ammonium to nitrogen? Is there a hydraulic head sufficient to
drive nitrate or chloride from the vadose zone to groundwater? If the answer to any of
these is no, this potential source can be eliminated. If a possible source has been identified,
perform a Weight of Evidence analysis to determine if the possible source has contributed
to the plume. If the possible source has been determined to have contributed to the plume,
perform a hydrogeologic and mass balance analysis to determine to what extent the source
has contributed to the plume.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 72 August 18, 2011
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22. Chem Lab
Hypothesis 22: Ammonium-, nitrate-, or chloride-bearing chemicals from the Chem Lab
may have spilled or leaked, or lab sink drain water may have leaked from the underground
piping that conveys lab drain wastes to the tailings cells. Ammonium-, nitrate-, or
chloride-laden water from the lab may have leached through the alluvial soil and bedrock
to groundwater and contributed to the plume. This potential source is inaccessible to
geoprobe and core drilling equipment and is low priority due to generally small amounts of
nitrate that it could possibly have contributed to groundwater. Therefore, no sampling will
be conducted at this location.
Known Conditions: The Chem Lab is approximately 1,800 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonium-bearing chemicals,
or chloride-bearing chemicals used in this lab and at what time periods? b) Did this
potential source have sufficient mass to have contributed measurably to nitrate and/or
chloride observed in the plume? c) If only ammonium-bearing compounds were used, is
there an oxidation source adjacent to or beneath the lab sufficient to convert ammonium to
nitrogen? d) Is there a hydraulic head sufficient to drive nitrate from the vadose zone to
groundwater? And e) Has there been sufficient time since this potential source was put into
service for detectable levels of constituents from this potential source to reach the plume?
If this potential source could have contributed to the plume, is the Isotopic Fingerprint
statistically comparable to the Isotopic Fingerprint of the plume? If the Isotopic
Fingerprint of the potential source is statistically comparable to the Isotopic Fingerprint of
the plume, is it uniquely comparable or does the Weight of Evidence indicate that it
contributed to the plume?
Data Needs for Decision: Data on the use of ammonium-bearing, nitrate-bearing, and
chloride-bearing compounds in this lab. Data on concentrations of the same chemical
constituents in groundwater. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need data on the types and amounts of chemicals used at this facility. Data on
concentrations of nitrate, chloride, and ammonium are already available from the
groundwater and nitrate monitoring programs. Possible need for Isotopic Analysis data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If no nitrate-bearing, ammonium-bearing or chloride-bearing compounds
were used in this lab, this potential source can be eliminated. If any of these compounds
were used, is there an oxidation source adjacent to or beneath the lab sufficient to convert

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 73 August 18, 2011
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ammonium to nitrogen, and is there a hydraulic head sufficient to drive nitrate or chloride
from the vadose zone to groundwater? If not, this potential source can be eliminated.
Perform a hydrogeologic evaluation to determine if any potential contamination from this
potential source could have contributed to the plume. If not, this potential source is ruled
out. If the hydrogeologic analysis is not conclusive, proceed as follows. If a possible
source has been identified, perform a Weight of Evidence analysis to determine if the
possible source has contributed to the plume. If the possible source has been determined to
have contributed to the plume, perform a hydrogeologic and mass balance analysis to
determine to what extent the source has contributed to the plume.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 74 August 18, 2011
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23. Met Lab
Hypothesis 23: Ammonium-, nitrate-, or chloride-bearing chemicals from the Met Lab
may have spilled or leaked, or lab sink drain water may have leaked from the underground
piping used to convey lab drain wastes to the tailings cells. Ammonium-, nitrate-, or
chloride-laden water from the lab may have leached through the alluvial soil and bedrock
to groundwater and contributed to the plume. This potential source is inaccessible to
geoprobe and core drilling equipment and is a low priority due to generally small amounts
of nitrate that it could possibly have contributed to groundwater. Therefore no sampling
will be conducted at this location.
Known Conditions: The Met Lab is approximately 1,800 feet downgradient of the
upgradient margin of the main plume.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonium-bearing chemicals,
or chloride-bearing chemicals used in this lab and at what time periods? b) Did this
potential source have sufficient mass to have contributed measurably to nitrate and/or
chloride observed in the plume? c) If only ammonium-bearing compounds were used, is
there an oxidation source adjacent to or beneath the lab sufficient to convert ammonium to
nitrogen? d) Is there a hydraulic head sufficient to drive nitrate from the vadose zone to
groundwater? And e) Has there been sufficient time since this potential source was put into
service for detectable levels of constituents from this potential source to reach the plume?
If this potential source could have contributed to the plume, is the Isotopic Fingerprint
statistically comparable to the Isotopic Fingerprint of the plume? If the Isotopic
Fingerprint of the potential source is statistically comparable to the Isotopic Fingerprint of
the plume, is it uniquely comparable or does the Weight of Evidence indicate that it
contributed to the plume?
Data Needs for Decision: Data on the use of ammonium-bearing, nitrate-bearing, and
chloride-bearing compounds in this lab. Data on concentrations of the same chemical
constituents in groundwater. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need data on the types and amounts of chemicals used at this facility. Data on
concentrations of nitrate, chloride, and ammonium are already available from the
groundwater and nitrate monitoring programs. Possible need for Isotopic Analysis data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: Perform a hydrogeologic evaluation to determine if any potential
contamination from this potential source could have contributed to the plume. If not, this
potential source is ruled out. If the hydrogeologic analysis is not conclusive, proceed as

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 75 August 18, 2011
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follows. If no nitrate-bearing, ammonium-bearing, or chloride-bearing compounds were
used in this lab, this potential source can be eliminated. If any of these compounds were
used, is there an oxidation source adjacent to or beneath the lab sufficient to convert
ammonium to nitrogen, and is there a hydraulic head sufficient to drive nitrate or chloride
from the vadose zone to groundwater? If not, this potential source can be eliminated. If a
possible source has been identified, perform a Weight of Evidence analysis to determine if
the possible source has contributed to the plume. If the possible source has been
determined to have contributed to the plume, perform a hydrogeologic and mass balance
analysis to determine to what extent the source has contributed to the plume.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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24. V2O5 oxidation tanks
Hypothesis 24-1: Ammoniated solutions from the V2O5 oxidation area could have spilled
or overflowed, entered the floor drains and/or drain sumps, and leaked out of the drains and
through the alluvial soil and bedrock into groundwater before entering the tailings system,
contributing to the plume. Anhydrous ammonia is added to raffinate solution from the
uranium solvent extraction area in this part of the plant. Nitrogen in this area is solely in
the ammonium (NH4+) form. Anything spilled or washed down to floors or sumps is
pumped back from the sumps into the process and remains within the building. If this were
a source of contamination, there would need to be evidence of a breach or failure of the
building floor or the sump. Ammonium cations are typically strongly retarded in a soil-
water system and likely would not travel through the alluvium and bedrock in the ammonia
form. It would have to be converted to nitrate from a process above the alluvium or in the
near subsurface. That is, there would have to be a source of oxygenated water or other
oxidizing fluid (such as a pond) immediately below or adjacent to the ammonium tanks,
and it would have to create sufficient head to drive nitrated water all the way to
groundwater.
Known Conditions: The V2O5 Oxidation Tanks are approximately 1,700 feet downgradient
of the upgradient margin of the main plume.
Necessary Conditions: a) Is there evidence of a failure of the floor sump and/or floor
drains? b) Is there an oxidation source adjacent to or beneath the tanks sufficient to convert
ammonium to nitrate? c) Is there a hydraulic head sufficient to drive nitrate from the
vadose zone to groundwater? d) Did this potential source have sufficient mass to have
contributed measurably to nitrate observed in the plume? e) Has there been sufficient time
since this potential source was put into service (circa 1980) for detectable levels of
constituents from this potential source to reach the plume? Note that there would need to
be sufficient time for any ammonium to be oxidized to nitrate, for nitrate to be transported
to groundwater, and then be transported to the downgradient edge of the plume. And
f) Since this potential source is not associated with any chloride, is there a plausible
alternate source for chloride? If this potential source could have contributed to the plume,
is the Isotopic Fingerprint statistically comparable to the Isotopic Fingerprint of the plume?
If the Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Information on the condition and history of the floor, drains, and
sumps in the building. Data on the concentration of nitrate, chloride, ammonium, dissolved
oxygen, and oxidation reduction potential in the groundwater adjacent to this feature.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
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Possible need for Isotopic Analysis data. Possible need for Non-Isotopic Groundwater
Data (for Weight of Evidence analysis).
Data Gaps: Need information on the structure and history of the floors and drains. Need
nitrate, ammonium, and dissolved oxygen from adjacent monitor wells. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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Hypothesis 24-2: Sodium chlorate or chlorinated solutions from the V2O5 oxidation area
could have spilled or overflowed, entered the floor drains and/or drain sumps, and leaked
out of the drains and through the alluvial soil and bedrock into groundwater before entering
the tailings system, contributing to the plume. Anything spilled or washed down to floors
or sumps is pumped back from the sumps into the process and remains within the building.
If this were a source of contamination, there would need to be evidence of a breach or
failure of the building floor or the sump. If this were an appreciable source, it would also
be associated with measurably elevated sodium in soil and/or groundwater adjacent to and
beneath the tank area. Sodium chlorate is a not a source of nitrogen atoms, and this
hypothesis has been retained for evaluation only as a chloride source.
Necessary Conditions: a) Is there evidence of chloride concentrations in the vadose zone
beneath this feature? b) Did this potential source have sufficient mass to have contributed
measurably to chloride observed in the plume? c) Does the hydrogeology support and
explain transport to groundwater? And d) Has there been sufficient time since this potential
source was put into service (1979) for detectable levels of constituents from this potential
source to reach groundwater? If this potential source could have contributed to the plume,
is the Isotopic Fingerprint statistically comparable to the Isotopic Fingerprint of the plume?
If the Isotopic Fingerprint of the potential source is statistically comparable to the Isotopic
Fingerprint of the plume, is it uniquely comparable or does the Weight of Evidence indicate
that it contributed to the plume?
Data Needs for Decision: Information on the condition and history of the floor, drains, and
sumps in the building. Data on the concentration of nitrate, chloride, ammonium, dissolved
oxygen, and oxidation reduction potential in the groundwater adjacent to this feature.
Possible need for Isotopic Analysis data. Possible need for Non-Isotopic Groundwater
Data (for Weight of Evidence analysis).
Data Gaps: Need information on the structure and history of the floors and drains. Need
nitrate, ammonium, and dissolved oxygen from adjacent monitor wells. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine

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if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the
groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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25. Natural nitrate reservoir
Hypothesis 25: Increased recharge or irrigation of dry land could have led to leaching of
salts that have been accumulating in the unsaturated zone for thousands of years, forming a
nitrate reservoir in the subsurface alluvium which is driven through the alluvial soil and
bedrock to groundwater by surface water (wildlife or other ponds) percolation.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone? b) Did this potential source have sufficient mass to have contributed
measurably to nitrate and/or chloride observed in the plume? c) Does the hydrogeology
support and explain transport to groundwater? And d) Has there been sufficient time for
detectable levels of constituents from this potential source to reach the plume? If this
potential source could have contributed to the plume, is the Isotopic Fingerprint statistically
comparable to the Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the
potential source is statistically comparable to the Isotopic Fingerprint of the plume, is it
uniquely comparable or does the Weight of Evidence indicate that it contributed to the
plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, and ammonium in
the alluvial and bedrock portion of the vadose zone beneath this feature. Possible need for
Isotopic Analysis data. Possible need for Non-Isotopic Groundwater Data (for Weight of
Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Possible need for Isotopic Analysis data. Possible need for
Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Decision Process: If the results of Phase 1 sampling of the alluvium provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), conduct coring study of bedrock to groundwater
(Phase 3). Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If the results of Phase 3 sampling of the bedrock provide evidence that
any of the constituents (nitrate, chloride, or ammonium) are present above two times
background (as defined in Section 3.3.1), perform a hydrogeologic evaluation to determine
if this potential source could have generated sufficient mass during the time frame required
to produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, perform a
mass balance to determine source viability. If the source is viable, move to Phases 4 and 5
Isotopic Fingerprint analysis of groundwater, alluvial soil, and bedrock core. If the

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groundwater and potential source fingerprints match to a reasonable degree, the Weight of
Evidence suggests that a source has been identified. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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26. – 32. Other ponds or pond like sources
Hypothesis 26: These areas were used historically as agriculture-related stock ponds and
fertilizer mixing ponds. Anecdotal evidence suggests ponds may have been used for sheep
dipping, that occasionally cattle broke through the ice and drowned, and that truckloads of
salt crystals were deposited in the vicinity for the cattle. Nitrates and chlorides associated
with these agricultural-related activities may have leached through the alluvial soil and
bedrock to groundwater. While not always present in soils and groundwater associated
with cattle wastes and byproducts, cryptosporidium is frequently present in livestock and
animal sources, not human or industrial (chemical) sources. If detected along with elevated
nitrate, the presence of cryptosporidium would help to earmark the source of nitrate as
being of livestock/animal origin. There is also the potential for military activity in
connection with any of the historical ponds near the Site.
Necessary Conditions: a) Is there evidence of nitrate and chloride concentrations in the
vadose zone beneath this feature? b) Did this potential source have sufficient mass to have
contributed measurably to nitrate and/or chloride observed in the plume? c) Does the
hydrogeology support and explain transport to groundwater? And d) Has there been
sufficient time since this potential source was put into service for detectable levels of
constituents from this potential source to reach groundwater? If this potential source could
have contributed to the plume, is the Isotopic Fingerprint statistically comparable to the
Isotopic Fingerprint of the plume? If the Isotopic Fingerprint of the potential source is
statistically comparable to the Isotopic Fingerprint of the plume, is it uniquely comparable
or does the Weight of Evidence indicate that it contributed to the plume?
Data Needs for Decision: Data on the concentration of nitrate, chloride, ammonium, and
cryptosporidium in the alluvial and bedrock portion of the vadose zone beneath this feature.
Data on concentrations of chemical constituents in groundwater that might be associated
with agricultural or military uses of this feature. Possible need for Isotopic Analysis data.
Possible need for Non-Isotopic Groundwater Data (for Weight of Evidence analysis).
Data Gaps: Need nitrate, chloride, and ammonium concentration data from the bedrock
portion of the vadose zone. Data on concentrations of chemical constituents in
groundwater that might be associated with agricultural or military uses of this feature.
Possible need for Isotopic Analysis data. Possible need for Non-Isotopic Groundwater
Data (for Weight of Evidence analysis).
Decision Process: Collect data on concentrations of chemical constituents in groundwater
that might be associated with agricultural uses of this feature along with cryptosporidium
(Phase 2). If cryptosporidium is present along with elevated nitrate in water or alluvium,
support is provided for an agricultural source.

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If the results of Phase 1 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), conduct coring study of bedrock to groundwater (Phase 3).
Analyze bedrock core samples for nitrate, chloride, and ammonium concentration data. If
the results of Phase 3 sampling of the bedrock provide evidence that any of the constituents
(nitrate, chloride, or ammonium) are present above two times background (as defined in
Section 3.3.1), perform a hydrogeologic evaluation to determine if this potential source
could have generated sufficient mass during the time frame required to produce the plume
and if there was a plausible pathway for any potential contamination from this potential
source to have contributed to the plume. If the results of the hydrogeologic evaluation are
negative, the Weight of Evidence suggests that this feature is not a potential source. If the
results of the hydrogeologic evaluation are positive, perform a mass balance to determine
source viability. If the source is viable, move to Phases 4 and 5 Isotopic Fingerprint
analysis of groundwater, alluvial soil, and bedrock core. If the groundwater and potential
source fingerprints match to a reasonable degree, the Weight of Evidence suggests that a
source has been identified. If the mass balance determines that the potential source is not
viable, the Weight of Evidence suggests that a source has not been identified.
If the results of Phase 1 sampling of the alluvium do not provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above two times background (as
defined in Section 3.3.1), proceed to a hydrogeologic evaluation to determine if this
potential source could have generated sufficient mass during the time frame required to
produce the plume and if there was a plausible pathway for any potential contamination
from this potential source to have contributed to the plume. If the results of the
hydrogeologic evaluation are negative, the Weight of Evidence suggests that this feature is
not a potential source. If the results of the hydrogeologic evaluation are positive, proceed to
a mass balance to determine source viability. If the mass balance determines that the
potential source is not viable, the Weight of Evidence suggests that a source has not been
identified. If the mass balance determines that the potential source is viable, the Weight of
Evidence suggests that a source has been identified.

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2.4 Environmental Receptor Identification
Environmental receptors can include humans or other living organisms (ecological receptors)
potentially exposed to and adversely affected by contaminants because they are present at the
source(s) or along the contaminant migration pathway.
2.4.1 Humans
Humans are a potential receptor because they may be present at the source; however nitrate and
chloride in soil pose no risk to humans. Humans do not come in contact with groundwater at the
Site; therefore, the human risk pathway is incomplete. That is, there is no exposed human
individual, no human health risk, and no environmental concern associated with humans.
2.4.2 Ecological
Potential ecological receptors are not at risk from nitrates and chlorides in soil. Potential
ecological receptors do not come in contact with groundwater at the Mill Site; therefore, the
ecological risk pathway is incomplete. That is, there is no exposed ecological receptor, no
ecological risk, and no environmental concern associated with ecological receptors.

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3.0 DATA GENERATION AND ACQUISITION
3.1 Phase 1 Geoprobe Investigation of Background, Natural Nitrate Reservoir,
and Potential Site Sources
The purpose of the Phase 1 investigation was to determine background concentrations of nitrate
and chloride in the alluvial soil column in undisturbed areas in the vicinity of the Mill, to locate a
natural nitrate and chloride reservoir in the alluvial soil, and to compare nitrate and chloride
concentrations found in soil near potential Mill sources to background concentrations. The
Phase 1 investigation is described in more detail in DUSA’s May 13, 2011, submittal to the DRC
titled Nitrate Investigation Revised Phase 1 Work Plan, White Mesa Mill Site, Blanding, Utah
(INTERA, 2011).
3.2 Phase 2 Groundwater Quality Sampling and Analysis
The purpose of groundwater sampling for non-isotopic analytes is to test the hypotheses that
nitrate and chloride mass observed in groundwater was caused by either military or agricultural
uses of the White Mesa Site and to:
1. Establish background for comparison to analytes not already addressed in the Mill’s
existing background study reports and monitoring programs.
2. Produce valid data for comparison to background.
3. Identify locations of groundwater elevated in the constituents of concern.
4. Provide data for incorporation in the CSM and decision process regarding nitrate sources.
A separate Detailed Work Plan and QAP was submitted to the DRC on July 13, 2011. The Phase
2 Detailed Work Plan and QAP specifies the specific details, activities, equipment, procedures,
objectives, and decision criteria for this phase of the investigation. The Phase 2 Detailed Work
Plan and QAP is based upon the existing DRC-approved QAP for groundwater sampling at the
White Mesa Mill. The Phase 2 Detailed Work Plan and QAP follows the same outline as the
approved QAP and: a) supplements the approved QAP to address additional activities which are
specific to Phase 2 of the nitrate investigation and are not currently addressed in the QAP, and
b) adjusts existing procedures in the approved QAP which need to be modified or omitted to be
suitable for the nitrate investigation.
3.2.1 Sampling Design
The following analytes will act as a “fingerprint” of either military or agricultural activities:
• Cryptosporidium

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• RDX
• HMX
• Perchlorate
It is assumed that any such uses would be associated with ponds or pond-like features to carry
constituents to groundwater. Not all locations with elevated nitrate and chloride are associated
with an active pond. However, disturbances visible on aerial imagery far upgradient and far
downgradient near wells containing elevated concentrations of nitrate and chloride may have
been related to historical ponds at those locations. Therefore, the following wells, which are also
presented on Figure 21 and Table 3, will be sampled for non-isotopic constituents:
• MW-20
• MW-31
• TWN-19
• TWN-2
• TWN-9
• TWN-17
• MW-19
• MW-27
• MW-30
• TW4-1
• TW4-22
• TW4-24
TWN-2 and TW4-22 will be sampled for cryptosporidium, RDX, and HMX. The other wells will
be analyzed for perchlorate only.
3.2.2 Field Activities and Sampling Methods
Field activities are described in detail in the Phase 2 Detailed Work Plan and QAP.
3.2.2.1 Sample Identification
Each sample collected at the Site during the nitrate investigation will be identified using a unique
sample identification number (“ID”). The description of the sample type and the point name will
be recorded on the chain-of-custody (“COC”) forms, as well as in the field notes.

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Field log books will be used to document field sampling information. Sample IDs will be listed
on the sample labels and the COC forms submitted to the laboratory, and will be cross-
referenced to the name in permanently bound field log books, on sample data sheets, and on
COC forms.
Ground water samples will be named according to the well ID where the sample was collected.
QC samples will be named as follows:
• Duplicate samples will be identified with a fictitious name and time which will be
recorded in the field log book.
• Equipment blanks will also have a fictitious name and time which will be recorded in the
field log book.
3.2.3 Sample Containers and Holding Times
All sample containers will be supplied by the laboratory and will be certified as new. The type of
sample containers to be used for each analysis, the sample volumes required, the preservation
requirements, and the holding times for samples prior to extraction and analysis are presented in
Table 1 of the Phase 2 QAP (DUSA, 2011).
3.2.4 Analytical Methods
3.2.4.1 Field Analytical Methods
Field parameters will be collected according to Section 6.2 of the Phase 2 QAP.
3.2.4.2 Laboratory Analytical Methods
Groundwater samples will be submitted to the analytical laboratory for analysis. A list of
analytes and their analytical methods is presented below:
Explosives (RDX and HMX) EPA Method 8330
Perchlorate EPA Method 6850
Cryptosporidium EPA Method 1623
3.3 Phase 3 Deep Bedrock Core Sampling and Analysis
The objective of deep bedrock core sampling and analysis is to trace nitrate and chloride from
the base of the alluvium and into the bedrock column (Dakota Formation and upper Burro
Canyon Formation) to the water table. The coring will take place in two separate sub-phases:

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1. Phase 3A Deep Bedrock Coring in Undisturbed Locations.
2. Phase 3B Deep Bedrock Coring of Potential Nitrate Source Locations.
Analytical results and data collected from Phase 1 of the nitrate investigation will be shared with
the DRC. DUSA and the DRC will decide on coring locations based on data and discussion.
3.3.1 Sampling Design
Phase 3A: At this time it is anticipated that at least four coring locations associated with locating
the natural nitrate reservoir will be chosen based on field test kit and analytical results from the
20 background soil borings advanced during Phase 1A of this investigation. Figure 22 presents
the potential locations for coring. Preliminary results from Phase 1A indicate the presence of a
nitrate and chloride spike at one of the deeper, undisturbed alluvial locations with nitrate and
chloride concentrations rising gradually with depth to a peak and then falling with depth below
the peak. This observation is consistent with the findings reported by Walvoord, et al. (2003), in
which they described a natural nitrate reservoir beneath desert soils. Some alluvial borings at
undisturbed locations saw the highest concentrations of nitrate and chloride at the base of the
alluvial material. Still other borings yielded samples in which there was no detected nitrate or
chloride in alluvial materials. The alluvium is generally thin at the Mill property, and the
presence of a nitrate and chloride spike in the deepest of the alluvial borings suggests that
evidence of a natural nitrate reservoir may be found in the upper part of the bedrock at the
undisturbed sites. Therefore, the bedrock cores to test the natural nitrate reservoir hypothesis will
be advanced through the alluvial soil to approximately 20 feet below the surface of the bedrock,
and samples will be taken at 4-foot intervals for shipment to the Analytical Laboratory.
Remaining core will be archived. If any nitrate and/or chloride are detected above two times
background (background is defined as the 95% upper confidence interval of data collected in
Phase 1A) in samples sent to the Analytical Laboratory, additional samples from adjacent
intervals will be selected from the archived core and sent for Analytical Laboratory analysis. All
samples will undergo an SPLP leaching procedure and the leachate will be analyzed for nitrate,
chloride, sulfate, and ammonium.
Phase 3B: One coring location associated with each pond or pond-like source and each potential
process-related source where nitrate and chloride are detected above two times background in
alluvial material will be selected based on analytical results from the source borings conducted
in Phase 1B of this investigation. The bedrock core will be advanced through the alluvium and
bedrock to groundwater. For all deep bedrock borings drilled, the depth of each will extend to the
upper geologic contact of the Brushy Basin Member of the Morrison Formation. Water levels in
the perched aquifer have been relatively stable for the last 20 years. Therefore, the presence of
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would provide strong evidence that a source had indeed contributed those constituents to
groundwater. Three (3) samples will be collected from each bedrock core location. Bedrock
core samples will be collected randomly from the first ⅓, second ⅓, and third ⅓ interval of the
total penetrated depth at each location, but during the evaluation of results, special emphasis will
be placed on the sample from the interval above the groundwater table. All samples will
undergo an SPLP leaching procedure and the leachate will be analyzed for nitrate, chloride,
sulfate, and ammonium. If nitrate and/or chloride are detected above two times background as
defined in section 3.3.1 in samples sent to the Analytical Laboratory, additional coring will be
collected from the same location during Phase 5.
3.3.2 Field Activities and Sampling Methods
The coring will be conducted with a conventional truck-mounted drill rig using a combination of
hollow-stem auger and air-rotary methods, without introducing water or other drilling fluids into
the borehole.
Cores will be logged by a Utah-Licensed Professional Geologist. Photographs of cores will be
collected and GPS coordinates will be recorded.
No field testing will be conducted on these rock cores. The core intervals for Analytical
Laboratory analysis will be packaged and shipped to a State of Utah-certified Analytical
Laboratory for analysis for the presence of nitrate, chloride, sulfate, and ammonium in the rock
cores following the SPLP leaching method. The Analytical Laboratory will need to crush,
pulverize, and blend the rock core material before conducting the analysis. Results will be
reported in milligrams per kilogram (“mg/kg”).
The core-hole borings will be backfilled with hydrated bentonite after drilling. The as-built
boring locations will be recorded with a hand-held GPS instrument for plotting on the Mill Site
map and for future reference in the field.
Equipment decontamination will be implemented for all non-disposable equipment that comes in
contact with bedrock before moving equipment to a new location or collecting a new sample.
Commercial third-party deionized water will be used for rinsate blank collection.
3.3.2.1 Sample Identification
Each sample collected at the Site during the nitrate investigation will be identified using a unique
sample ID. The description of the sample type and the point name will be recorded on the COC
forms, as well as in the field notes.

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Field log books will be used to document field sampling information. Sample IDs will be listed
on the sample labels and the COC forms submitted to the Analytical Laboratory, and will be
cross-referenced to the name in permanently bound field log books, on sample data sheets, and
on COC forms.
Coring samples will be named according to the coring location and top and bottom of the depth
interval at which they were collected, following the convention C-††X-tt-dd, where †† X is the
core location which will be previously determined based on the soil boring locations given in
Phase 1, tt is the top of the depth interval, and dd is the bottom of the depth interval expressed in
feet bgs. For example, the sample collected at C-01A in the depth interval between 25 and 26
feet bgs would be named C-01A-25-26.
QC samples will be named as follows:
• Duplicate samples will have the same name as the parent sample with a D added at the
end of the sample name.
• Equipment blanks will have the same name as the boring location with a terminal RB
added at the end.
3.3.3 Sample Containers and Holding Times
The type of sample containers to be used for each analysis, the sample volumes required, the
preservation requirements, and the holding times for samples prior to extraction and analysis are
presented in Tables 4 and 5.
3.3.4 Analytical Methods
All rock samples will be submitted to the Analytical Laboratory for SPLP analysis using EPA
Method 1312 using Extraction Fluid #3. Method 1312 will produce a leachate of all rock
samples which will be analyzed for nitrate, chloride, sulfate, and nitrogen as ammonium using
EPA Method 353.2, EPA Method 300.0, and EPA Method 350.1 respectively.
3.4 Phase 4 Stable Isotopic Sampling and Analysis of Groundwater in Existing
Wells
The purpose of the Phase 4 isotopic sampling and analysis is to provide additional data, if
required, to support or reject hypotheses presented in this Nitrate Investigation Revised Phases 2
through 5 Work Plan, including the hypothesis of a natural nitrate source and hypotheses
regarding Mill Site sources.

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The most direct method for identifying the source of nitrate in the Mill site plume should be
similarity in isotopic composition, this assumes that the nitrogen at the point of origin has a
unique signature, and that the isotopic composition did not change or it changed predictably
during migration. It is already acknowledged that for the Mill site, many of the potential nitrate
sources such as human and animal waste should have nitrate isotopic values that are similar to
each other within a range. These sources occur in several locations, existed over different time
frames, and may contribute indistinguishable nitrate; however, the individual sources may have
unique location specific co-migrating species which will be examined. Similarly, other sources
are different from wastewater, but the range of known isotopic signatures overlap with
wastewater and in such cases the variety of isotopes being analyzed may draw the needed
distinction. Nevertheless, the expectation is that the nitrate in the Mill site plume may have been
derived from a very limited number of sources in which case the possibility of circumventing the
problem of overlap is improved; conversely, multiple sources with overlapping signatures may
not provide the needed unequivocal source identification.
The analyses of nitrate (δ15N) isotopic composition may be distinctive when compared among
background monitoring wells, nitrate plume, chloroform plume, and other selected monitoring
wells. Similarly, when these data are compared with other potential discriminators such as the
δ18O-NO3, as well as chemical concentration and isotopic signature of a co-migrating species
like sulfate and ammonium, the distinction may be definitive. Comparisons of all data will be
made to known ranges of values for sources identified for this site. Subsequent analysis will
search for clusters of values, or trends in values that indicate compositions similar to sources, or
indicate mixing between endmembers.
In the final analysis, an acceptable identification of source(s) for the nitrate in the groundwater
must ultimately conform to the composition of an existing source, or conform to the signature
that a source would have had based on historical or literature values, or be tested against residual
signatures of sources in soil or aquifer material (Phase 5). Furthermore, the suspected sources
must be plausibly related to the nitrate plume with respect to the hydrogeology, proximity,
reaction pathway, and time frame. If the analysis of data does not yield interpretable populations
or trends, and instead yields an ill-defined overlap of results, then additional testing and analysis
using other indicator species may be recommended.
3.4.1 Sampling Design
The conventional isotopic measurements for nitrate, ammonium, and sulfate will be performed
on groundwater samples from the Mill Site to attempt to determine the source and degree of
mixing of these compounds in groundwater in light of chemical and hydrologic data already
available. Samples will be collected for nitrate (δ15N, δ18O-NO3), ammonium (δ15N), and sulfate

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(δ34S, δ18O-SO4) isotopic analysis from selected well locations based on existing conceptual
models to attempt to determine the Isotopic Fingerprint or ratios in groundwater in the selected
wells. Each well will be purged and monitored until key parameters stabilize. Samples will be
collected and analyzed for:
1. Analytical concentration of dissolved nitrate (EPA method 353.2), ammonium (EPA
method 350.1), and chloride and sulfate (using EPA Method 300.0).
2. Isotopic composition.
All samples will be preserved, shipped, and analyzed in accordance with a new QAP to be
developed for isotopic groundwater sampling and analysis. This new QAP (the “Phase 4 QAP”)
will specify the specific details, activities, equipment, procedures, objectives, schedules,
laboratories, and decision criteria for this phase of the investigation. The Phase 4 QAP will be
based upon and utilize the existing DRC-approved QAP for groundwater sampling at the White
Mesa Mill. The Phase 4 QAP will follow the same outline as the existing approved QAP for
groundwater sampling at the Mill and will supplement the approved QAP to address those
activities which are specific to Phase 4 of the nitrate investigation.
The Phase 4 QAP will address the following additional requirements:
• Schedule for sampling
• Sample turnaround
• Selected laboratory(ies)
• Analytical methods
• Sample volumes
• Minimum detection limits for analytes
• Field QA procedures
• Laboratory QC
Wells will be sampled along a transect essentially north to south through the long axis of the
nitrate-chloride plume approximately parallel to the estimated direction of groundwater flow.
Wells that will be sampled within the mapped nitrate-chloride plume include TWN-3, TWN-2,
TW4-22, TW4-24, and MW-31. Similarly, wells will be sampled from within the separate
nitrate-chloroform plume to characterize the nitrogen accompanying infiltration from the septic
leach fields (TW4-18, TW4-11, and TW4-1). Well locations containing elevated tritium
indicating the groundwater contained a component of recent recharge (Hurst and Solomon, 2008)
will be sampled for the isotopes listed above to expand the application of these results to

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potential surface sources (MW-30, MW-27, and MW-19, in addition to MW-31 already
identified). In addition, water samples will be collected from two (2) distinct occurrences of
elevated nitrate in groundwater upgradient and northeast of the Mill Site plumes, and from one
downgradient location southwest of the Mill Site, to determine if the nitrate sources are similar
or if there is continuity of transport processes across the Site (TWN-19, TWN-17, TWN-9, and
MW-20) (Figure 23 and Table 6).
Two specific technical concepts are incorporated in this isotopic Phase to improve the
probability of interpreting what is often an inconclusive overlap of signature for nitrogen isotopic
data in discriminating among multiple sources. First the δ18O of both sulfate and nitrate
molecules will be analyzed because the exchange of oxygen isotopes in these molecules occurs
in both atmospheric and aqueous environments. The consequence of this analysis is that
different 18O/16O ratios are indicative of the antecedent environment, which further contributes to
interpretation of solute source and evolutionary pathway.
Secondly, nitrogen may be present as ammonium in the groundwater in wells affected by septic
leach field drainage or infiltration from the Historical Pond or natural wildlife ponds. If nitrate
and/or ammonium are detected in the groundwater chemical analysis, then the sample will be
tested for δ15N of ammonium as well as nitrate.
3.4.2 Field Activities and Sampling Methods
Field activities will be described in detail in the Phase 4 Detailed Work Plan and QAP.
3.4.2.1 Sample Identification
Each sample collected at the Site during the nitrate investigation will be identified using a unique
sample ID. The description of the sample type and the point name will be recorded on the COC
forms, as well as in the field notes.
Field log books will be used to document field sampling information. Sample IDs will be listed
on the sample labels and the COC forms submitted to the laboratory, and will be cross-
referenced to the name in permanently bound field log books, on sample data sheets, and on
COC forms.
Groundwater samples will be named according to the well ID where the sample was collected.
QC samples will be named as follows:
• Duplicate samples will be identified with a fictitious name and time which will be
recorded in the field log book.

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• Equipment blanks will also have a fictitious name and time which will be recorded in the
field log book.
3.4.3 Sample Containers and Holding Times
All sample containers will be supplied by the laboratory and will be certified as new. The type of
sample containers to be used for each analysis, the sample volumes required, the preservation
requirements, and the holding times for samples prior to extraction and analysis will be presented
in Table 1 of the Phase 4 QAP.
3.4.4 Analytical Methods
3.4.4.1 Field Analytical Methods
Field parameters will be collected according to Section 6.2 of the Phase 4 QAP.
3.4.4.2 Laboratory Analytical Methods
Groundwater and wastewater samples will be submitted to the analytical laboratory for isotopic
analysis. SOPs from the analytical laboratory are included as Appendix D.
3.5 Phase 5 Isotopic Soil Sampling and Analysis
A determination regarding the necessity to complete Phase 5 will be made after review of the
data obtained from the previous phases of the nitrate investigation. For example, if the isotopic
values of nitrogen and sulfur in groundwater samples analyzed in Phase 4 indicate that a
distinction can be made among potential sources, then Phase 5 will be pursued. Criteria for
evaluating isotopic data are described in Section 3.4. The objective of this phase is to identify
potential and possible endmember source candidates and characterize the nitrogen and sulfur
isotopic composition according to the criteria described in Section 2.3.3.1 of this Nitrate
Investigation Revised Phases 2 through 5 Work Plan.
This sampling will include:
(a) Any soils and/or bedrock that DUSA determines could represent a natural nitrate reservoir.
(b) Any soils and/or bedrock representative of any of the Phase 1 or 3 Mill Site sources that
DUSA and the executive Secretary agree, based on the results from Phase 1 or Phase 3,
could have contributed to the plume.
(c) Influents to any sewage vault or leach field identified in paragraph B as requiring isotopic
analysis.

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Each sample will be collected and analyzed for:
1. Analytical concentration of dissolved nitrate, ammonium, chloride, and sulfate (using EPA
Methods to be identified in the QAP).
2. Isotopic composition.
Samples will be collected for nitrogen, oxygen (δ15N, δ18O-NO3), and sulfate (δ34S, δ18O-SO4)
isotopic analysis according to the criteria in Section 2.3.3.1 of this Nitrate Investigation Revised
Phases 2 through 5 Work Plan to evaluate the possibility of each being a source.
Representative leach samples will be collected from background alluvial boring sediments from
three (3) natural nitrate reservoirs and three (3) gypsum lithologies for nitrogen and sulfur
isotopic composition respectively. Samples from each boring or medium will be collected at
approximately the same intervals as specified in Phases 1 and 3 for non-isotopic characterization
in this Nitrate Investigation Revised Phases 2 through 5 Work Plan. Since isotopic results from
these potential samples will be compared directly to Isotopic Fingerprints of groundwater,
background samples are not required.
All samples will be collected, preserved, shipped, and analyzed following a separate QAP to be
developed for isotopic sampling and analysis of soil, extracts, and manufactured products. The
QAP will be submitted specifying the specific details, activities, equipment, procedures,
laboratories, procedures, schedules, and decision criteria for this phase of the investigation. The
QAP will be based upon and utilize the existing DRC-approved QAP for groundwater sampling
at the White Mesa Mill. The QAP will follow the same outline as the approved QAP and will
supplement the approved QAP to address those activities which are specific to Phase 5 of the
nitrate investigation.
The QAP will address the following additional requirements:
• Schedule for sampling
• Sample turnaround
• Selected laboratory(ies)
• Analytical methods
• Sample volumes
• Minimum detection limits for analytes
• Field QA procedures
• Laboratory QC

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3.6 Sample Handling and Custody
3.6.1 Sample Labeling
Alluvial material will be collected in glass jars. Deep bedrock core samples will be collected in
resealable plastic bags due to the inflexible nature of the samples and the inability to “fit” rock
cores into a traditional sample jar.
Resealable plastic bags which are archived will be labeled with an indelible marker with the
following information:
• Sample identification
• Date
Alluvium and deep bedrock cores provided to the Analytical Laboratory for analysis will be
labeled with an adhesive label showing the following information:
• Sample identification
• Date
• Time of collection
• Project name
• Sampler’s initials
• Analysis required
Glass jars and resealable bags will be sealed and placed on ice in a cooler.
3.6.2 Sample Documentation
Documentation during sampling is essential to proper sample identification. All personnel will
adhere to the following general guidelines for maintaining field documentation:
• Documentation will be completed in permanent black or blue ink.
• All entries will be legible.
• Errors will be corrected by crossing out the entry with a single line and then dating and
initialing the lineout.
• Any serialized documents will be maintained by INTERA and referenced in the field log
book.

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• Unused portions of pages will be crossed out, and each page will be signed and dated.
The field team leader and sampling personnel are responsible for proper documentation of
activities.
3.6.3 Chain of Custody
Standard sample custody procedures will be used to maintain and document sample integrity
during collection, transportation, storage, and analysis. A sample will be considered to be in
custody if one of the following statements applies:
• It is in a person’s physical possession or view.
• It is in a secure area with restricted access.
• It is placed in a container and secured with an official seal in such a way that the sample
cannot be reached without breaking the seal.
COC procedures provide an accurate written record that traces the possession of individual
samples from the time of collection in the field to the time of acceptance at the Analytical
Laboratory. The COC form will also be used to document all samples collected and the analyses
requested. Information that the field personnel will record on the COC form includes the
following:
• Project name and number
• Sampling location
• Name and signature of sampler
• Destination of sample (Analytical Laboratory name)
• Sample ID
• Date and time of collection
• Number and type of containers filled
• Analyses requested
• Preservatives used (if applicable)
• Filtering (if applicable)
• Signatures of individuals involved in custody transfer, including the date and time of
transfer
• Air bill number (if applicable) or courier information
• Project contact and phone number

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Unused lines on the COC form will be crossed out. Field personnel will sign COC forms. The
COC form will be placed in a waterproof plastic bag and taped to the inside of the shipping
container used to transport the samples. Signed air bills will serve as evidence of custody transfer
between field personnel and the courier, and between the courier and the Analytical Laboratory.
Copies of the COC form and the air bill will be retained and filed by field personnel before the
containers are shipped.
The Analytical Laboratory sample custodian will receive all incoming samples, sign the
accompanying COC forms, and retain copies of the forms as permanent records. The Analytical
Laboratory sample custodian will record all pertinent information concerning the samples,
including the persons delivering the samples, the date and time received, sample condition at the
time of receipt (e.g., sealed, unsealed, or broken container; temperature; or other relevant
remarks), the sample IDs, and any unique Analytical Laboratory IDs for the samples. When the
sample transfer process is complete, the custodian is responsible for maintaining internal log
books, tracking reports, and other records necessary to maintain custody throughout sample
preparation and analysis.
The Analytical Laboratory will provide a secure storage area for all samples. Access to this area
will be restricted to authorized personnel. The custodian will ensure that samples requiring
special handling, including samples that are heat- or light-sensitive or radioactive, or that have
other unusual physical characteristics, are properly stored and maintained pending analysis.
3.6.4 Sample Shipment
The following procedures will be implemented when samples collected during the remediation
activities are shipped:
• The cooler will be filled with bubble wrap, sample containers, and packing material.
Sufficient packing material will be used to minimize sample container breakage during
shipment.
• The COC forms will be placed inside a plastic bag. The bag will be sealed and taped to
the inside of the cooler lid. The air bill, if required, will be filled out before the samples
are handed over to the carrier. The Analytical Laboratory will be notified if the sampler
suspects that the sample contains any substance that would require Analytical Laboratory
personnel to take safety precautions.
• The cooler will be closed and taped shut with packing tape around both ends. If the
cooler has a drain, it will be taped shut both inside and outside of the cooler.
• Signed and dated custody seals will be placed on the front and side of each cooler. Wide
clear tape will be placed over the seals.

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• The COC form will be transported within the taped, sealed cooler. When the cooler is
received at the Analytical Laboratory, Analytical Laboratory personnel will open the
cooler and sign the COC form to document transfer of samples.
• Multiple coolers may be sent in one shipment to the Analytical Laboratory. The outsides
of the coolers will be marked to indicate the number of coolers in the shipment.
3.7 Quality Control
3.7.1 Field Quality Control Methods
Field QC measures include complete documentation of all field activities on the appropriate
forms. Field QC samples include the collection of field duplicates for analysis by the Analytical
Laboratory. Field duplicates will be collected at a frequency of 1 duplicate per 10 field samples.
Duplicates will be collected by mixing the field sample and splitting the sample into 2
containers. The samples will be labeled as separate samples and submitted blind to the Analytical
Laboratory. Duplicate assessment will be completed as described in Section 3.7.3.4, below.
3.7.2 Analytical Laboratory Quality Control Methods
Analytical QA/QC will be governed by the QA/QC program of the Analytical Laboratory. Every
effort will be made to use Analytical Laboratories that are certified by the State of Utah and by
NELAP and/or NAVLAP, and are capable of performing the analytical procedures specified in
the Phase 2 Work Plan and QAP, and have a QA/QC program that includes the spikes, blanks,
and duplicates described below.
3.7.2.1 Spikes, Blanks, and Check Samples
Analytical Laboratory QC samples will assess the accuracy and precision of the analyses.
Following are descriptions of the types of QC samples that may be used by the Analytical
Laboratory to assess the quality of the data. Analytical QC will be completed as required by the
specific method used for analysis. Assessment of Analytical Laboratory QC samples will be as
specified in the method.
a. Matrix Spike/Matrix Spike Duplicate
A spiked field sample analyzed in duplicate may be analyzed with every analytical batch.
Analytes stipulated by the analytical method, by applicable regulations, or by other
specific requirements may be spiked into the samples. Selection of the sample to be
spiked depends on the information required and the variety of conditions within a typical
matrix. The matrix spike sample serves as a check evaluating the effect of the sample
matrix on the accuracy of analysis. The matrix spike duplicate serves as a check of the

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analytical precision. Assessment of the matrix spike/matrix spike duplicate will be
completed using the method- and Analytical Laboratory-established limits.
b. Method Blanks
Each analytical batch shall be accompanied by a method blank. The method blank shall
be carried through the entire analytical procedure. Contamination detected in analysis of
method blanks will be used to evaluate any Analytical Laboratory contamination of
environmental samples which may have occurred. Method blank detections will be
assessed to determine if there is any effect on the sample data usability. Method blank
effects will be discussed and a determination made on a case-by-case basis.
c. Check Samples
Each analytical batch shall contain a number of check samples. For each method, the
Analytical Laboratory will analyze the check samples or their equivalents specified in the
analytical method. Check samples may include a laboratory control sample (“LCS”),
calibration checks, laboratory fortified blanks, or sample duplicates. Check samples will
be reviewed for compliance with the Analytical Laboratory and method-specified
acceptance limits.
3.7.3 Internal Quality Control Checks
3.7.3.1 Field Quality Control Check Procedures
The QA Manager will perform the QA/QC analysis of field procedures as described below.
3.7.3.2 Review of Compliance with Procedures in this Work Plan
Observation of technician performance is monitored by the QA Manager on a periodic basis to
ensure compliance with this work plan.
3.7.3.3 Completeness Review
The QA Manager will review all analytical results to confirm that the analytical results are
complete (i.e., there is an analytical result for each required constituent). The completeness goal
for this project is 95%.
3.7.3.4 Duplicates
The following analysis will be performed on duplicate field samples:
• Relative percent difference.

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RPDs will be calculated in comparisons of duplicate and original field sample results. Non-
conformance will exist when the RPD is greater than 35, unless the measured concentrations are
less than 5 times the required detection limit (EPA, 1994b).
3.7.3.5 Use of QC Samples to Assess Conformance with this Work Plan
QC samples generated during field activities and in the Analytical Laboratory will be used to
assess the usability of the data for meeting project objectives. QC data which do not meet the
requirements specified herein may require that the associated sample data be flagged for limited
use or be removed from the overall data pool. Data flagging will follow standard EPA guidelines
specified in Functional Guidelines as applicable to the analytical method. QC samples will be
used to determine if the data meet the project objectives.
3.7.4 Instrument Equipment Testing, Inspection, and Maintenance
The Analytical Laboratory is responsible for the maintenance of its instruments in accordance
with Analytical Laboratory procedures and as required in order to maintain its NELAP and/or
NAVLAP certifications. Preventive maintenance will be performed on a scheduled basis to
minimize downtime and the potential interruption of analytical work.
Sampling and field equipment shall be tested, inspected, and maintained in accordance with
manufacturers’ recommendations.
3.7.5 Instrument Calibration
A fundamental requirement for collection of valid data is the proper calibration of all sample
collection and analytical instruments. Analytical Laboratory equipment shall be calibrated in
accordance with Analytical Laboratory procedures and as described in the analytical methods.

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4.0 DATA EVALUATION
Data evaluation will be completed as described throughout this work plan. Analytical data will
be evaluated as described using Analytical Laboratory generated QC samples as specified in the
analytical methods. Field data will be evaluated against the specific QC samples generated in the
field and documentation will be reviewed for completeness and accuracy.
For the SPLP, Extraction Fluid #3 will be used. Standard extraction requires the addition of
nitric acid and sulfuric acid during the leaching process. Since the leachates will be analyzed for
nitrate+nitrite and sulfate, the deionized leaching process contemplated by the method (for
cyanide-containing samples) will be used in lieu of the standard leaching procedure.
As previously described, the soil samples are being leached and analyzed using water
methodologies, which will yield concentrations in liquid units (such as mg/L). During the data
interpretation and preparation of a revised CSM, the calculations and/or the relationship for
converting the results to soil mass units will be provided.
Data usability will be assessed based on compliance with the QC standards specified in the
analytical method.
Separate detailed work plans and QAPs will be provided for Phases 2, 4, and 5 which will
describe the data evaluation process to be used for each of those phases.

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5.0 AUDITS
DUSA may perform system and performance audits in order to ensure that data of known and
defensible quality are produced during a sampling program. The frequency and timing of system
and performance audits shall be as determined by DUSA.
5.1 System Audits
System audits are qualitative evaluations of all components of field and Analytical Laboratory
QC measurement systems. They determine if the measurement systems are being used
appropriately. System audits will review field and Analytical Laboratory operations, including
sampling equipment, Analytical Laboratory equipment, sampling procedures, and equipment
calibrations, to evaluate the effectiveness of the QA program and to identify any weakness that
may exist. The audits may be carried out before all systems are operational, during the program,
or after the completion of the program. Such audits typically involve a comparison of the
activities required under this work plan with those actually scheduled or performed. A special
type of systems audit is the data management audit. This audit addresses only data collection and
management activities.
5.2 Performance Audits
The performance audit is a quantitative evaluation of the measurement systems of a program. It
requires testing the measurement systems with samples of known composition or behavior to
evaluate precision and accuracy. With respect to performance audits of the analytical process,
either blind performance evaluation samples may be submitted to the Analytical Laboratory for
analysis, or the auditor may request that it provide results of the blind studies that the Analytical
Laboratory must provide to its NELAP and/or NAVLAP accreditation agency on an annual
basis. The performance audit is carried out without the knowledge of the analysts, to the extent
practicable.
5.3 Follow-Up Actions
Response to the system audits and performance audits is required when deviations are found.
5.4 Audit Records
Audit records for all audits conducted will be retained in DUSA Central Files. These records will
contain audit reports, written records of completion for corrective actions, and any other
documents associated with the audits supporting audit findings or corrective actions.

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6.0 REFERENCES
ASTM International. 2009. Standard Practice for Description and Identification of Soils ASTM
D2488-09a.
––––––. 2010. Standard Practice for Classification of Soils for Engineering Purposes (Unified
Soil Classification System) ASTM D 2487 – 10.
Aubrey, W. M. 1989. Mid-Cretaceous Alluvial-Plain Incision Related to Eustasy, Southeastern Colorado Plateau. Geological Society of America Bulletin101: 443-449.
Denison Mines (USA) Corp. (DUSA). 2009. Initial Nitrate Monitoring Report.
––––––. 2010-2011. Quarterly Nitrate Reports.
––––––. 2011. White Mesa Uranium Mill Phase 2 Nitrate Investigation Detailed Work Plan and
Schedule (QAP). July 12, 2011 (Revision 1).
Hunt, G. L. 1996. Environmental Handbook, Environmental Regulations for the Oil & Gas
Exploration and Production Industry. Prepared by G. L. Hunt, Environmental Manager,
Utah Division of Oil, Gas and Mining. January 1996.
Hurst, T.G., and D.K. Solomon. 2008. Summary of Work Completed, Data Results,
Interpretations and Recommendations for the July 2007 Sampling Event at the Denison Mines, USA, White Mesa Uranium Mill. University of Utah Department of Geology and
Geophysics. May 2008.
Hydro Geo Chem, Inc. (HGC). 2005. Perched Monitoring Well Installation and Testing at the
White Mesa Uranium Mill, April Through June, 2005. Submitted to International
Uranium (USA) Corporation, Denver, Colorado.
––––––. 2009. Site Hydrogeology and Estimation of Groundwater Pore Velocities in the Perched
Zone White Mesa Uranium Mill Site Near Blanding, Utah
INTERA, Inc. 2009. Nitrate Contamination Investigation Report, White Mesa Uranium Mill
Site, Blanding, Utah.
––––––. 2011. Nitrate Investigation Revised Phase I Work Plan, White Mesa Mill Site, Blanding, Utah. May 13, 2011.
Scanlon, B.R., R.C. Reedy, D.A. Stonestrom, D.E. Prudic, and K.F. Dennehy. 2005. “Impact of
Land Use and Land Cover Change on Groundwater Recharge and Quality in the
Southwestern US,” in Global Change Biology, v. 11, 1577-1593.
Tischler, Jo Ann, 2009. Preliminary Source Review Report for Nitrate and Chloride in Groundwater at the White Mesa Mill.

Nitrate Investigation Revised Phases 2-5 Work Plan Rev. 2.0
White Mesa Mill Site, Blanding, Utah 105 August 18, 2011
S:\Projects\IUC-001-01-001 Denison Mines\2010\Nitrate Response\!Work Plan\new_theory_sap\Phase2-5\CommentsRevisions\PHASE2-5WORKPLAN_FINAL_08182011.docx
U.S. Department of Energy (“DOE”). 2004. “Remediation of the Moab Uranium Mill Tailings,
Grand and San Juan Counties, Utah, Draft Environmental Impact Statement”, Chapter
3.4, DOE/EIS-0355D, November 2004.
U.S. Environmental Protection Agency (EPA). 1994a. Test Methods for Evaluating Solid Waste,
Physical/Chemical Methods, USEPA publication SW-846, Third Edition. Chapter 1, Section 5.
–––––. 1994b. EPA Contract Laboratory Program National Functional Guidelines for Inorganic
Data Review, 9240.1-05-01. February. P. 25.
Walvoord, M.A., F.M. Phillips, D.A. Stonestrom, R.D. Evans, P.C. Hartsough, B.D. Newman,
and R.G. Striegl. 2003. “A Reservoir of Nitrate Beneath Desert Soils,” in Science, v. 302, 1021-1024.

FIGURES

191
ENTRANCE SPRING
CORRAL SPRING
RUIN SPRINGS
COTTONWOOD SEEP
WESTWATER SEEP
CORAL CANYON SEEP
0.5 0 0.50.25
Miles
Source(s): Utah GIS Portal website
Legend
DUSA Property Boundary
Monitoring Well
Piezometer
Regional Well
Spring/Seep
Surface Water
Chloroform Monitoring Well
Nitrate Monitoring Well
Windmill
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure1_SiteMap.mxd
Figure 1
Map Showing Location
of White Mesa Mill Site
Nitrate Investigation Revised
Phase 2-5 Work Plan
MW-01
MW-18
PIEZ-1
MW-19
PIEZ-2
MW-27
TW4-21 PIEZ-3
TW4-22
TW4-20
TW4-19 TW4-18
TW4-5
TW4-25
TW4-24
TW4-9 TW4-12
TW4-13TW4-2
TW4-8
TW4-1
MW-04
TW4-11TW4-16
MW-26
MW-32MW-31
MW-30
MW-28
TW4-10
TW4-3
TW4-23 TW4-6
TW4-4 TW4-14
PIEZ-4
MW-25
MW-11
MW-02
MW-24
MW-29
MW-12
MW-05
MW-23
MW-16
MW-15
MW-14
MW-17
MW-03A
MW-03
MW-20
MW-21
MW-22
Cell No. 1
Mill Site
Cell No. 2
Cell No. 3
Cell No. 4A
WildlifePond
WildlifePond
WildlifePond
TW4-7
TWN-9
TWN-13
TWN-17
TWN-19
TWN-12TWN-11
TWN-16
TWN-15
TWN-14
TWN-10
TWN-6
TWN-8TWN-5
TWN-7
TWN-18
TWN-3
TWN-2 TWN-4
TWN-1
5
10
15
20 25
25
5
5
30
20
15
10
5
5

WESTWATER SEEP
ENTRANCE SPRING
CORAL CANYON SEEP
FROG POND
Lawzy Lake

PIEZ-5
10
Cell No. 4B
Source(s): Aerial – Utah GIS Portal website;Wells – HGC, Inc., May 2008 report.
Legend
Monitoring Well
Piezometer
Spring/Seep
Surface Water
Chloroform Monitoring Well
Nitrate Monitoring Well
Nitrate Concentration (mg/L)
Nitrate data from Contamination Investigation Report (INTERA, 2009). Boundary of plume has not changed significantly since 2009.
Figure 2Map Showing Nitrate PlumeNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure2_Nitrate.mxd
1,200 0 1,200600Feet
MW-01
MW-18
PIEZ-1
MW-19
PIEZ-2
MW-27
TW4-21 PIEZ-3
TW4-22
TW4-20
TW4-19 TW4-18
TW4-5
TW4-25
TW4-24 TW4-9 TW4-12
TW4-13TW4-2
TW4-8
TW4-1
MW-04
TW4-11TW4-16
MW-26
MW-32
MW-31
MW-30
MW-28 TW4-10
TW4-3
TW4-23 TW4-6
TW4-4 TW4-14
PIEZ-4
MW-25
MW-11
MW-02
MW-24
MW-29
MW-12
MW-05
MW-23
MW-16
MW-15
MW-14
MW-17
MW-03A
MW-03
MW-20
MW-21
MW-22
Cell No. 1
Mill Site
Cell No. 2
Cell No. 4A
WildlifePond
WildlifePond
WildlifePond
TW4-7
TWN-9
TWN-13
TWN-17
TWN-19
TWN-12TWN-11
TWN-16
TWN-15
TWN-14
TWN-10
TWN-6
TWN-8TWN-5
TWN-7
TWN-18
TWN-3
TWN-2 TWN-4
TWN-1

WESTWATER SEEP
ENTRANCE SPRING
CORAL CANYON SEEP
10
0
Cell No. 3
200
300
300
400
500
10
0
100
100Lawzy Lake
FROG POND
PIEZ-5
Source(s): Aerial – Utah GIS Portal website;Wells – HGC, Inc., May 2008 report.
Legend
Monitoring Well
Piezometer
Spring/Seep
Surface Water
Chloroform Monitoring Well
Nitrate Monitoring Well
Chloride Concentration (mg/L)
Figure 3Map Showing Chloride PlumeNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure3_Chloride.mxd
1,200 0 1,200600Feet
Chloride data from Contamination Investigation Report (INTERA, 2009). Boundary of plume has not changed significantly since 2009.
Cell No. 1
Mill Site
Cell No. 2
Cell No. 3
Cell No. 4A
WildlifePond
WildlifePond
5
5
5
5
5

FROG POND

100
100
100
100
Cell No. 4B
Cell 1 Leach Field [7]1979-1985
CCD [18]
V205 Oxidation Tanks [24]
Fly Ash Pond [8]
Chem Lab [22]
Met Lab [23]
Former OfficeLeach Field [4]
Sewage Vault [2]
Scale House Leach Field [3]1977-1979
Main Leach Field [1]1985-Present
Ammonium SulfateCrystal Tanks [10]
Ammonia Tanks [5]
V205 Mini Lab & V205 Precip [20]
YC Precip Mini Lab [19]
SAG Leach Field [6]1998-2009
Lawzy Sump [11]
Wildlife Pond [17]
SX Mini Lab [21]
Former Vault [13] 1992-2009
Lawzy Lake [12]
Truck Shop1979-1985Leach Field [14]
Chlorate Tanks [9]
New CCD/SXLeach Field [15]2009-Present
Historical Pond [16]
Source(s): Aerial – Utah GIS Portal websiteLegend
Chloride Concentration (mg/L)
Nitrate Concentration (mg/L)
Inaccessible Potential Mill Site Source –No Geoprobe Boring
Leach Field (currently in operation)Sampling Method to be Determined
Potential Mill Site Source –Geoprobe Boring
Other Potential Nitrate andChloride Source – Geoprobe Boring
Pipeline Figure 4Map Showing Nitrate andChloride Plumes TogetherNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure4_NitrateChloride.mxd
1,000 0 1,000500Feet
Data from Contamination Investigation Report (INTERA, 2009).Boundary of plume has not changed significantly since 2009.
MW-01
MW-18
PIEZ-1
MW-19
PIEZ-2
MW-27
TW4-21 PIEZ-3
TW4-22
TW4-20
TW4-19 TW4-18
TW4-5
TW4-25
TW4-24
TW4-9
TW4-12
TW4-13TW4-2
TW4-8
TW4-1
MW-04
TW4-11TW4-16
MW-26
MW-32
MW-31
MW-30
MW-28
TW4-10
TW4-3
TW4-23 TW4-6
TW4-4 TW4-14
PIEZ-4
MW-25
MW-11
MW-02
MW-24
MW-29
MW-12
MW-05
MW-23
MW-16
MW-15
MW-14
MW-17
MW-03A
MW-03
MW-20
MW-21
MW-22
Cell No. 1
Mill Site
Cell No. 2
Cell No. 3
Cell No. 4A
WildlifePond
WildlifePond
WildlifePond
TW4-7
TWN-9
TWN-13
TWN-14
TWN-10
TWN-6
TWN-8TWN-5
TWN-7
TWN-18
TWN-3
TWN-2
TWN-4
TWN-1
5
10
15
20
25
25
5
30
20
15
10
5
5

WESTWATER SEEP
Lawzy Lake
PIEZ-5
Cell No. 4B
Source(s): Aerial – EDAC, dated 1968;Wells – HGC, Inc., May 2008 report.
Legend
Monitoring Well
Piezometer
Spring/Seep
Surface Water
Chloroform Monitoring Well
Nitrate Monitoring Well
Nitrate Concentration (mg/L)
Figure 5Nitrate Plume Overlain on1968 Aerial PhotographNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure5_1968Nitrate.mxd
900 0 900450Feet
Nitrate data from Contamination Investigation Report (INTERA, 2009). Boundary of plume has not changed significantly since 2009.
MW-4 4.6
0 6.6
PIEZ-19 7
TWN-1~ 0.5
EXPLANATION
perched monitoring well showing
concentration in mg/L
temporary perched monitoring well
showing concentration in mg/L
perched piezometer showing
concentration in mg/L
temporary perched nitrate monitoring well
showing concentration in mg/L
HYDRO
GEO
CH EM , I NC. APPROVED
MW-1Se !':lS
KRIGED 1st QUARTER, 2011 NITRATE (mg/L)
(NITRATE + NITRITE AS N)
AND LOCATIONS OF CROSS-SECTIONS
SW-NE NW-SE AND SW2-NE2
DATE REFERENCE
SJS H:/718000lmay11 /photobase/phntq1 xsf6.srf
FIGURE
6
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.
EXPLANATION
Qaf
Km
Kdbc
Jmbb
Alluvium/Fill
Mancos Shale
Dakota Sandstone/
Burro Canyon Formation
Brushy Basin Member of
Morrison Formation
Shale in Dakota /
Burro Canyon Formation
Conglomerate in Dakota /
Burro Canyon Formation
SW NE
INTERPRETIVE NORTHEAST-SOUTHWEST
CROSS SECTION (NE-SW)
WHITE MESA SITE
H:/718000/dakota/xsection/nsxsectb_rev2.srf
Approximate Area >10 mg/L Nitrate
Approximate Area >100 mg/L Chloride
Piezometric Surface
0 2000 4000 6000 8000 10000 12000 14000
distance along cross-section (feet)
5420
5440
5460
5480
5500
5520
5540
5560
5580
5600
5620
5640
5660
5680
5700
5720
5740
5760
el
e
v
a
t
i
o
n

(
f
e
e
t

a
m
s
l
)
MW
-
2
0

MW
-
0
3

MW
-
1
4

MW
-
1
1

MW
-
3
1

TW
4
-
2
4
MW
-
2
7

TW
N
-
2

TW
N
-
3

TW
N
-
1
8
TW
N
-
8

TW
N
-
6

TW
N
-
1
0
TW
N
-
1
5
TW
N
-
1
6
TW
N
-
1
2
Fl
y

A
s
h

P
o
n
d
Ce
l
l

1

L
e
a
c
h

F
i
e
l
d
CC
D
/
S
X

L
e
a
c
h

F
i
e
l
d
Hi
s
t
o
r
i
c
a
l

P
o
n
d
La
w
z
y

L
a
k
e
Q1,2011 Nitrate, Chloride in mg/L:
Q4,2010 Nitrate, Chloride in mg/L:
Q3,2010 Nitrate, Chloride in mg/L:
Q2,2010 Nitrate, Chloride in mg/L:
ND, 32
ND, 34
ND, 31
ND, 32
21, 145
20, 138
21, 139
23, 128
31, 1100
31, 522
31, 587
30, 639
6.0, 46
5.7, 45
6.9, 42
5.8, 42
43, 93
48, 93
69, 104
69, 97
24, 138
24, 117
27, 106
26, 118
1.4, 61
1.6, 59
1.8, 64
1.8, 63
ND, 13
ND, 9.0
ND, 11
ND, 11
1.1, 18
1.2, 21
1.4, 73
1.4, 22
0.3, 40
1.3, 28
0.2, 21
1.0, 30
1.4, 43
1.2, 38
1.0, 36
1.0, 39
4.6, 34
2.0, 30
2.6, 35
1.3, 35
4.2, 87'
0.7, 103
0.7, 112
0.8, 106
Cell # 4A
Cell # 3
Cell # 2 Cell # 1
Kdbc
Kdbc
Kdbc
Km
Km
Km
Jmbb
Jmbb
Jmbb
Qaf
Qaf
vertical exaggeration = 20 : 1
5/24/11SJS 7
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC. H:/718000/dakota/
xsection/ns2xsect/ns2xsectb_rev2.srf
SW2 NE2
INTERPRETIVE NORTHEAST-SOUTHWEST
CROSS SECTION (NE2-SW2)
WHITE MESA SITE
EXPLANATION
Qaf
Kdbc
Jmbb
Alluvium/Fill
Dakota Sandstone/
Burro Canyon Formation
Brushy Basin Member of
Morrison Formation
Shale in Dakota /
Burro Canyon Formation
Conglomerate or Conglomeratic
Sandstone in Dakota /
Burro Canyon Formation
Approximate Area
>100 mg/L Chloride
Piezometric Surface
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
distance along cross section (feet)
5450
5470
5490
5510
5530
5550
5570
5590
5610
5630
5650
5670
5690
5710
5730
5750
el
e
v
a
t
i
o
n

(
f
e
e
t

a
m
s
l
)
TW
N
-
1
8
MW
-
1
9

PI
E
Z
-
1
TW
N
-
9

TW
N
-
1
4
TW
N
-
1
7
TW
N
-
1
9
Q1,2011 Nitrate, Chloride in mg/L:
Q4,2010 Nitrate, Chloride in mg/L:
Q3,2010 Nitrate, Chloride in mg/L:
Q2,2010 Nitrate, Chloride in mg/L:
1.4, 61
1.6, 59
1.8, 64
1.8, 63
NS, NS
2.4, 25
NS, NS
2.6, 28
7.0, 60
6.5, 60
6.8, 52
7.2, 52
9.5, 217
8.0, 172
10.7, 210
7.7, 175
3.7, 24
4.2, 28
3.5, 26
2.9, 30
8.6, 90
8.0, 65
8.9, 66
11, 87
7.0, 114
7.0, 107
7.2, 113
6.2, 113
Jmbb
Jmbb
Kdbc
Kdbc
Qaf
Notes: (1) approximately 200 feet north of cross section
(2) approximately 200 feet south of cross section
Approximate 5 mg/L
Nitrate Icocon
Approximate Area
> 10 mg/L Nitrate
5 vertical exaggeration = 8 : 1
5/24/11 8SJS
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200
distance along cross-section (feet)
5460
5480
5500
5520
5540
5560
5580
5600
5620
5640
5660
5680
5700
5720
5740
5760
el
e
v
a
t
i
o
n

(
f
e
e
t

a
m
s
l
)
TW
N
-
7

TW
N
-
2

TW
4
-
2
5
TW
4
-
2
1
TW
N
-
1

PI
E
Z
-
3
Hi
s
t
o
r
i
c
a
l

P
o
n
d
La
w
z
y

S
u
m
p
SA
G

L
e
a
c
h

F
i
e
l
d
Am
m
o
n
i
u
m

S
u
l
f
a
t
e

T
a
n
k
s

(
1
)
Am
m
o
n
i
a

T
a
n
k
s

(
2
)
Fo
r
m
e
r

O
f
f
i
c
e

L
e
a
c
h

F
i
e
l
d

(
3
)
Ma
i
n

L
e
a
c
h

F
i
e
l
d

(
4
)
Q1,2011 Nitrate, Chloride in mg/L:
Q4,2010 Nitrate, Chloride in mg/L:
Q3,2010 Nitrate, Chloride in mg/L:
Q2,2010 Nitrate, Chloride in mg/L:
1.3, 6.0
1.0, 4.0
1.6, 7.0
1.2, 6.0
43, 93
48, 93
69, 104
69, 97
15, 315
15, 312
14, 250
16, 306
9.0, 303
7.0, 210
14, 278
12, 266
0.5, 17
0.6, 14
0.6, 19
0.6, 20
1.8, 40
1.8, 25
1.8, 35
1.6, 36
QafKm
Km Km
Kdbc
Kdbc
Kdbc
Jmbb
Jmbb
Notes: (1) approximately 115 feet southwest of cross-section
(2) approximately 150 feet southwest of cross-section
(3) approximately 300 feet south of cross-section
(4) immediately south of cross-section
EXPLANATION
Qaf
Km
Kdbc
Jmbb
Alluvium/Fill
Mancos Shale
Dakota Sandstone/
Burro Canyon Formation
Brushy Basin Member of
Morrison Formation
Shale in Dakota /
Burro Canyon Formation
Conglomerate or Conglomeratic
Sandstone in Dakota /
Burro Canyon Formation
Piezometric Surface
Approximate Area
>10 mg/L Nitrate
Approximate Area
> 100 mg/L Chloride
INTERPRETIVE NORTHWEST-SOUTHEAST
CROSS SECTION (NW-SE)
WHITE MESA SITE
H:/718000/dakota/
xsection/ewxsect/ewxsectb_rev2.srf
NW SE
vertical exaggeration = 3 : 1
5/24/11 9SJS
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.
ELEVATION OF BEDROCK SURFACE
SHOWING THICKNESS OF MANCOS SHALE AND
CROSS SECTIONS SW-NE, NW-SE, AND SW2-NE2
H:/718000/dakota/
phbsrfmnthck_rev1.srf
EXPLANATION
tailings cell outline projected
onto bedrock surface
wildlife pond
perched monitoring well
or piezometer location
5560 top of bedrock
elevation contour
SW
NE
NE2
SW2NW
SE
5
10
15
20
25
30
35
40
th
i
c
k
n
e
s
s

o
f

M
a
n
c
o
s

S
h
a
l
e

(
f
e
e
t
)
10SJS
Figure 16Logic Diagram for Potential NaturalNitrate Reservoir Source InvestigationNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure16_LD_NRLD.mxd
Figure 17Logic Diagram for Potential ProcessRelated Source InvestigationNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure17_LD_PPRSI.mxd
Figure 18Logic Diagram for Potential Pondand Pond-Like Source InvestigationNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure18_LD_PPLF.mxd
Figure 19Logic Diagram forGroundwater InvestigationNitrate Investigation Revised Phase 2-5 Work Plan
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure19_LD_PNNRSI.mxd
MW-01
MW-18
PIEZ-1
MW-19
PIEZ-2
MW-27
TW4-21
PIEZ-3
TW4-22
TW4-20
TW4-19
TW4-18
TW4-5
TW4-25
TW4-24 TW4-9 TW4-12
TW4-13TW4-2
TW4-8
TW4-1
MW-04
TW4-11TW4-16
MW-26
MW-32
MW-31
MW-30
MW-28
TW4-10
TW4-3
TW4-23 TW4-6
TW4-4 TW4-14
PIEZ-4
MW-25
MW-11
MW-02
MW-24
MW-29
MW-12
MW-05
MW-23
MW-16
MW-15
MW-14
MW-17
MW-03A
MW-03
MW-20
MW-21
Cell No. 1
Cell No. 2
Cell No. 3
Cell No. 4A
WildlifePond
WildlifePond
TW4-7
TWN-9
TWN-13
TWN-17
TWN-19
TWN-12
TWN-11
TWN-16
TWN-15
TWN-14
TWN-10
TWN-6
TWN-8TWN-5
TWN-7 TWN-18
TWN-3
TWN-2 TWN-4
TWN-1

ENTRANCE SPRING
CORAL CANYON SEEP

PIEZ-5
Mill Site
Cell No. 4B
Lawzy Lake
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure21_Ph2gwSampleLocs.mxd
Figure 21Phase 2 GroundwaterSampling LocationsNitrate Investigation Revised Phase 2-5 Work Plan
1,000 0 1,000500Feet
Source(s): Aerial – Utah GIS Portal website, dated 2009;Wells – HGC, Inc., May 2008 report.
Legend
Wells used in Phase 2Groundwater Sampling
Monitoring Well
Piezometer
Spring/Seep
Surface Water
Chloroform Monitoring Well
Nitrate Monitoring Well
Cell No. 1 Mill Site
Cell No. 2
Cell No. 3
Cell No. 4A
Cell No. 4B
GP-14A
GP-17A
GP-05A
GP-15A GP-18A
GP-16A
GP-20A
GP-08A
GP-19A
GP-07A
GP-06A
GP-13A
GP-12A
GP-02A GP-03A
GP-11A
GP-04AGP-10A
GP-09AGP-01A
1,500 0 1,500750
Feet
Source(s): Utah GIS Portal website, dated 2009;
U.S. Geological Survey
Legend
Geoprobe Boring Location
Pershing Missile Staging Area
DUSA Property Boundary
Historical Disturbance (From 2009 Imagery)
Historical Disturbance (From 2006 Imagery)
Historical Disturbance (From 1997 Imagery)
Historical Disturbance (From 1984 Imagery)
Historical Disturbance (From 1973 Imagery)
Historical Disturbance (From 1955 Imagery)
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure22_CoringLocs.mxd
Figure 22
Phase 3 Potential
Coring Locations
Nitrate Investigation Revised
Phase 2-5 Work Plan
Frog Pond
Location of "Channel"
White Mesa Radar
Location of Barbed Wire
and Bullet Casings
MW-01
MW-18
PIEZ-1
MW-19
PIEZ-2
MW-27
TW4-21
PIEZ-3
TW4-22
TW4-20
TW4-19
TW4-18
TW4-5
TW4-25
TW4-24 TW4-9 TW4-12
TW4-13TW4-2
TW4-8
TW4-1
MW-04
TW4-11TW4-16
MW-26
MW-32
MW-31
MW-30
MW-28
TW4-10
TW4-3
TW4-23 TW4-6
TW4-4 TW4-14
PIEZ-4
MW-25
MW-11
MW-02
MW-24
MW-29
MW-12
MW-05
MW-23
MW-16
MW-15
MW-14
MW-17
MW-03A
MW-03
MW-20
MW-21
Cell No. 1
Cell No. 2
Cell No. 3
Cell No. 4A
WildlifePond
WildlifePond
TW4-7
TWN-9
TWN-13
TWN-17
TWN-19
TWN-12
TWN-11
TWN-16
TWN-15
TWN-14
TWN-10
TWN-6
TWN-8TWN-5
TWN-7 TWN-18
TWN-3
TWN-2 TWN-4
TWN-1

ENTRANCE SPRING
CORAL CANYON SEEP

PIEZ-5
Sewage Vault [2]Main Leach Field [1]1985-Present
New CCD/SXLeach Field [15]2009-Present
Mill Site
Cell No. 4B
Lawzy Lake
S:\Projects\IUC-001-01-001 Denison Mines\GIS\mapdocs\2011_Phase2-5\Figure23_Ph4gwSampleLocs.mxd
Figure 23Phase 4 GroundwaterSampling LocationsNitrate Investigation Revised Phase 2-5 Work Plan
1,000 0 1,000500Feet
Source(s): Aerial – Utah GIS Portal website, dated 2009;Wells – HGC, Inc., May 2008 report.Legend
Wells used in Phase 4Groundwater Sampling
Wastewater Sample -Only for Phase 4
Monitoring Well
Piezometer
Spring/Seep
Surface Water
Chloroform Monitoring Well
Nitrate Monitoring Well

TABLES
ID Task Name Finish
1 PHASE 1 GEOPROBE INVESTIGATION Fri 9/23/11
2 Potential Natural Nitrate Source Borings, field tests Fri 5/20/11
3 Potential Process Related Source Borings Mon 6/13/11
4 Laboratory Analysis SPLP Tue 7/5/11
5 Review and Interpret Data Mon 8/1/11
6 Phase 1 Results Report Fri 9/23/11
7 Submit Phase 1 Results Report to DRC Fri 9/16/11
8 Meeting to Review and Accept Data Fri 9/23/11
9 PHASE 2 GROUNDWATER SAMPLING FOR NON-ISOTOPIC ANALYTES Wed 12/7/11
10 Submit Groundwater QAP Addendum Thu 9/22/11
11 Water Sampling Thu 10/6/11
12 Laboratory Analysis Wed 11/9/11
13 Review and Interpret Data, Prepare Report Mon 11/28/11
14 Phase 2 Results Report Wed 12/7/11
15 Submit Phase 2 Results Report to DRC Tue 11/29/11
16 Meeting to Review and Accept Data Wed 12/7/11
17 PHASE 3 DEEP BEDROCK CORE SAMPLING AND ANALYSIS Fri 12/16/11
18 Potential Natural Nitrate Source Coring Tue 10/18/11
19 Potential Process Related Source Corings Thu 11/3/11
20 Laboratory Analysis SPLP Thu 12/1/11
21 Review and Interpret Data, Prepare Report Fri 12/16/11
22 Phase 3 Results Report Fri 12/16/11
23 Submit Phase 3 Results Report to DRC Fri 12/9/11
24 Meeting to Review and Accept Data Fri 12/16/11
25 HYDROGEOLOGIC EVALUATION Fri 12/16/11
26 Perform Evaluation Fri 12/16/11
27 Review Findings with DRC Fri 12/16/11
28 PHASE 4 STABLE ISOTOPE STUDY, LABORATORY ANALYSIS Fri 1/20/12
29 Submit Groundwater QAP Addendum Mon 9/26/11
30 Water Sampling from Existing Well Locations Fri 10/28/11
31 Laboratory Analysis Mon 12/12/11
32 Review and Interpret Data, Prepare Report Fri 1/13/12
33 Phase 4 Results Report Fri 1/20/12
34 Submit Phase 4 Results Report to DRC Fri 1/13/12
35 Meeting to Review and Accept Data Fri 1/20/12
36 PHASE 5 ISOTOPIC SOIL SAMPLING AND ANALYSIS (IF NEEDED)Wed 7/18/12
37 Quality Assurance Plan (QAP)Wed 3/28/12
38 Submit QAP Thu 2/16/12
39 DRC Review and Comment Wed 3/7/12
40 Finalization of Data Results Report Tue 3/27/12
41 DRC Approval Wed 3/28/12
42 Soil Boring at Identified Source*Mon 4/23/12
43 Laboratory Analysis Fri 6/15/12
44 Review and Interpret Data, Prepare Report Mon 7/9/12
45 Phase 5 Results Report Wed 7/18/12
46 Submit Phase 5 Results Report to DRC Tue 7/10/12
47 Meeting to Review and Accept Data Wed 7/18/12
48 REPORT OF FINDINGS Mon 12/31/12
49 Integrate Information from All Phases, Mass Balance and Hydrogeology Evaluatio Wed 9/19/12
50 Meeting to Review and Approve Mass Balance and Hydrogeology Wed 9/26/12
51 Final Mon 12/31/12
May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2012
Task
Split
Progress
Milestone
Summary
Project Summary
External Tasks
External Milestone
Deadline
Table 1. Work Plan Schedule
Denison White Mesa Mill Nitrate and Chloride Investigation
Page 1
*Soil sampling field work will not be performed prior to April 1 for safety reasons due to the ice and mud season.
Project: Table 1_Work Plan Schedule_Denison1 Date: Thu 8/18/11
Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 1 of 2
Well Date Chloride
(mg/L)
Data
Qualifier
Nitrate
(mg/L)
Data
Qualifier
MW-1 4/11/2011 18 0.1 U
MW-2 4/12/2011 7 0.1 U
MW-3 4/13/2011 64 0.3
MW-3A 4/13/2011 65 1.2
MW-4 6/1/2011 35 4.9 D
MW-5 4/12/2011 54 0.2
MW-11 4/4/2011 31 0.1 U
MW-12 4/5/2011 64 0.1 U
MW-14 4/4/2011 20 0.1 U
MW-15 4/12/2011 43 0.2
MW-17 5/25/2011 36 1.1
MW-18 4/6/2011 46 0.1 U
MW-19 4/6/2011 26 2.6 D
MW-20 4/11/2011 64 2.9 D
MW-22 4/6/2011 55 2.3 D
MW-23 4/11/2011 8 0.3
MW-24 4/5/2011 45 0.2
MW-25 4/4/2011 31 0.1 U
MW-26 6/20/2011 39 0.3
MW-27 4/5/2011 43 6.4 D
MW-28 4/11/2011 109 0.2
MW-29 4/5/2011 38 0.1 U
MW-30 6/20/2011 127 17 D
MW-31 6/20/2011 145 22 D
MW-32 5/25/2011 31 0.1 U
MW-34 4/13/2011 69 0.3
MW-35 4/12/2011 64 0.1 U
Piez-1 4/25/2011 58 6.8 D
Piez-2 4/25/2011 8 0.3
Piez-3 4/25/2011 35 1.7
TW4-1 6/1/2011 35 7 D
TW4-10 6/1/2011 42 3.3 D
TW4-11 6/1/2011 49 7.3 D
TW4-12 5/25/2011 32 7 D
TW4-13 5/25/2011 56 5.4 D
TW4-14 5/26/2011 24 1.4
TW4-15 5/31/2011 88 0.4
TW4-16 5/26/2011 81 5 D
TW4-17 2/23/2011 40 0.1 U
TW4-18 5/26/2011 36 9 D
Table 2: Summary of Most Recent
Chloride and Nitrate Concentrations in Groundwater
Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 2 of 2
Well Date Chloride
(mg/L)
Data
Qualifier
Nitrate
(mg/L)
Data
Qualifier
Table 2: Summary of Most Recent
Chloride and Nitrate Concentrations in Groundwater
TW4-19 6/7/2011 148 12 D
TW4-2 6/2/2011 42 6.8 D
TW4-20 6/1/2011 177 4.8 D
TW4-21 6/1/2011 297 13 D
TW4-22 6/1/2011 138 17 D
TW4-23 5/25/2011 44 0.1 U
TW4-24 5/26/2011 1110 35 D
TW4-25 5/25/2011 321 16 D
TW4-26 5/26/2011 15 10 D
TW4-3 5/25/2011 23 3.7 D
TW4-4 6/1/2011 35 7 D
TW4-5 5/26/2011 35 7.2 D
TW4-6 5/26/2011 42 0.3
TW4-7 6/1/2011 35 4 D
TW4-8 5/25/2011 45 0.1
TW4-9 5/25/2011 38 3.4 D
TWN-1 4/20/2011 19 0.5
TWN-10 4/21/2011 28 1.2
TWN-11 4/26/2011 76 1.4
TWN-12 4/26/2011 109 1
TWN-13 4/26/2011 49 0.1 U
TWN-14 4/27/2011 30 3.5 D
TWN-15 4/27/2011 49 1.6
TWN-16 4/27/2011 39 1.6 D
TWN-17 4/28/2011 81 9 D
TWN-18 4/26/2011 67 1.8
TWN-19 4/28/2011 120 6.9 D
TWN-2 4/28/2011 85 40 D
TWN-3 4/28/2011 128 26 D
TWN-4 4/20/2011 21 0.9
TWN-5 4/20/2011 44 0.3
TWN-6 4/20/2011 22 1.5
TWN-7 4/21/2011 6 1.7
TWN-8 4/19/2011 10 0.1 U
TWN-9 4/28/2011 192 10 D
UWLP 4/25/2011 1 U 0.1 U
Notes
U= Not detected at minimum detectable concentration
D= Reporting limit was raised due to sample matrix

Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 1 of 3
Monitoring Well
Location Sample IDa
Duplicate/MS/
MSD Location
ID
Date & Time
Sampled
Number of
Samples
Duplicate
Location IDa Matrix Analyte (Method)2 Sample Containers*Preservative Reporting Limit1 Holding Time Sample Temerature
Requirements Comments
MW-20 MW-20 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
MW-31 MW-31 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
TWN-19 TWN-19 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None 0.1 µg/L 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 ug/L 7 days to extraction/40 days
for extract ≤ 6oC
TWN-9 TWN-9 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
TWN-17 TWN-17 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
MW-19 MW-19 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
MW-27 MW-27 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
MW-30 MW-30 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
TW4-1 TW4-1 2 TW4-1D Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
TW4-24 TW4-24 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
TW4-24 TW4-24-RB 1 NA Aqueous Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
TWN-2 TWN-2 1 NA
TW4-22 TW4-22 1 NA Aqueous
Table 3: Phase 2 Groundwater Sampling Locations
AqueousX
Campaign 1
Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 2 of 3
Monitoring Well
Location Sample IDa
Duplicate/MS/
MSD Location
ID
Date & Time
Sampled
Number of
Samples
Duplicate
Location IDa Matrix Analyte (Method)2 Sample Containers*Preservative Reporting Limit1 Holding Time Sample Temerature
Requirements Comments
Table 3: Phase 2 Groundwater Sampling Locations

Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Campaign 2 (if needed)
Aqueous
DIFB DIFB 1 NA Aqueous
TW4-24 TW4-24 1 NAX
TW4-1 TW4-1 1 NA Aqueous
Aqueous
TWN-19 TWN-19 1 NA Aqueous
TWN-17 TWN-17 1 NA
Aqueous
TWN-9 TWN-9 1 NA Aqueous
TWN-2 TWN-2 1 NA
Aqueous
MW-31 MW-31 1 NA Aqueous
MW-30 MW-30 1 NA
1 NA Aqueous
MW-27 MW-27 1 NA Aqueous
MW-19 MW-19 1 NA Aqueous
MW-20 MW-20
Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 3 of 3
Monitoring Well
Location Sample IDa
Duplicate/MS/
MSD Location
ID
Date & Time
Sampled
Number of
Samples
Duplicate
Location IDa Matrix Analyte (Method)2 Sample Containers*Preservative Reporting Limit1 Holding Time Sample Temerature
Requirements Comments
Table 3: Phase 2 Groundwater Sampling Locations

Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
Cryptosporidium 1623 1 – 10 liter cubitainer None NA 96 hours until filtration ≤ 20oC
Explosives (RDX and HMX) EPA
8330
3 – 1 liter amber glass
bottles None 0.1 µg/L 7 days to extraction/40 days
for extract ≤ 6oC
Perchlorate EPA 6850 1 – 250 ml. polyethylene None 0.5 µg/L 28 days ≤ 10oC
X AqueousMW-18 MW-18 1 NA
Background Wells- Campaign 2
Aqueous
MW-12 MW-12 1 NA Aqueous
MW-3 MW-3 1 NA
Aqueous
MW-2 MW-2 1 NA Aqueous
MW-1 MW-1 1 NA
Aqueous
TWN-16 TWN-16 1 NA Aqueous
TWN-15 TWN-15 1 NA
NA Aqueous
TWN-13 TWN-13 1 NA Aqueous
TWN-8 TWN-8 1 NA Aqueous
TWN-11 TWN-11 1
a Duplicate sample locationS and equipment blank sample locations subject to change due to field conditions at discretion of field team leader
Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 1 of 1
Boring Locationa Sample Location
IDb,c
Date & Time
Sampled
Number of
Samples
DTW
(ft bgs)
TD
(ft bgs)
Sample Interval
(ft bgs)
Sample Interval
(ft bgs)
Sample Interval
(ft bgs)
Sample Interval
(ft bgs)
Sample Interval
(ft bgs)
Duplicate
Collected
Duplicate
Location IDc Matrix Minimum Sample
Mass/Volume
Sample
Containersd Analyte (Method)Comments
TBD C-††A-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††A-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††A-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††A-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††A-RB 1 NA Aqueous 250 mL
250 mL
Two (2) 4-oz,
Plastic or Glass
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††B-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††B-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††B-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††B-tt-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
TBD C-††B-RB 1 NA Aqueous 250 mL
250 mL
Two (2) 250-mL,
Plastic
Nitrate+Nitrite (EPA 353.2) Chloride
and Sulfate (EPA 300.0) Ammonia
(EPA 350.1)
b ††# is the location ID from Phase 1 and tt-dd is the sample depth interval
C-††A-tt-ddD
C-††B-tt-ddD
Table 4: Phase 3 Coring Sample Locations
Phase 3A - Deep Bedrock Coring in Undisturbed Locations
d Sample preservation methods and holding times shown in Table 5
a Locations to be determined upon receiving Phase 1 laboratory analytical results
Phase 3B - Deep Bedrock Coring of Potential Nitrate Source Locations
c Duplicate sample location and equipment blank sample location subject to change due to field conditions at discretion of field team leader

Nitrate Investigation Revised Phase 2-5 Work Plan August 18, 2011
White Mesa Mill Site Page 1 of 1
Table 5: Phase 3 Coring Laboratory Analytical Parameters
Analyte Analytical
Method
Reporting
Limit
Holding
Time
Preservation Temperature
Requirement
SPLP Leachate EPA 1312* NA 28 days None Cool to ≤4°C
Nitrate+Nitrite EPA 353.2 0.01 mg/L 28 days H2SO4 to a pH
<2** Cool to ≤4°C**
Chloride and
Sulfate
EPA 300.0 Chloride –
0.1 mg/L
Sulfate –
0.75 mg/L
28 days None** Cool to ≤4°C**
Ammonia as N EPA 350.1 0.05 mg/L 28 days H2SO4 to a pH
<2**
Cool to ≤4°C**

* Extraction Fluid 3 will be used. Standard extraction requires the addition of nitric acid and sulfuric acid during the leaching process. Since the
leachates will be analyzed for nitrate+nitrite and sulfate, the DI leaching process contemplated by the method (for cyanide containing
samples)will be used in lieu of the standard leaching procedure.
**Preservation and temperature requirements listed are for the leachates generated from the SPLP leaching procedure 1312 and for the
equipment rinsate samples collected during drilling activities.

Nitrate Investigation Revised Phase 2-5 Work Plan
White Mesa Mill Site
August 18, 2011
Page 1 of 1
Sample Location Sample IDa Date & Time
Sampled
Number of
Samples
Duplicate
Collected
Duplicate
Location IDa Analyte (Method)Comments
TWN-3 TWN-3 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TWN-2 TWN-2 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TW4-22 TW4-22 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TW4-24 TW4-24 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
MW-31 MW-31 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TW4-18 TW4-18 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TW4-18 TW4-18 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TW4-11 TW4-11 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TW4-1 TW4-1 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
MW-30 MW-30 2 MW-30D
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
MW-27 MW-27 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
MW-19 MW-19 2 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TWN-19 TWN-19 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TWN-17 TWN-17 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
TWN-9 TWN-9 1 NA
Nitrate+Nitrite (EPA 353.2)
Chloride and Sulfate (EPA 300.0)
Ammonia (EPA 350.1)
Nitrate Isotope Analysis
Ammonia Nitrogen Isotope Analysis
Sulfate Isotope Analysis
a Duplicate sample location and equipment sample location subject to change due to field conditions at discretion of field team leader
Table 6: Phase 4 Groundwater Isotopic Fingerprinting Sample Locations

APPENDIX A
INTERA Standard Operating Procedure 11 and U.S. Bureau of Reclamation’s Engineering Geology Field Manual
Standard Operating Procedures
SOP 11 – ROTARY DRILLING AND CORING

Updated January 9, 2004 SOP11-1
11.0 GENERAL
When installing monitoring wells in consolidated formations, the reliability and overall sample
quality of the drilled samples from either direct–fluid rotary or air, water, and foam systems is
very similar to that of the samples obtained in unconsolidated formations. Where reliable
samples are needed to fully characterize the monitored zone, it is suggested that cores be taken.
Coring can be conducted by either wireline or conventional methods. N-series split inner tube
core barrels are usually used. Air is the preferred drilling fluid. Dust control for air–rotary
methods is achieved through the use of a plastic diaper that fits around the back of the rig and
prevents dust migration. Techniques for obtaining and handling the cores are described below.
Both single– and double–tube core barrels may be utilized.
These guidelines are of necessity general in nature, as differing site conditions and project goals
may require adjustments and/or modifications to the procedures.

11.1 EQUIPMENT LIST
11.1.1 Core recovery and photography
 V trough to hold retrieved core
 camera
 Photographic bar scale
 index cards for photograph data (boring #, core run #, etc.).
11.1.2 Logging
 Measuring tape at least 10 feet long, graduated to at least 0.1 feet
 Hand lens
 Boring logs
 Geologist's hammer
 Knife
 Hydrochloric acid (5%)
 Protractor
 Small plastic ruler
 Pencils
 Munsell color chart
 Calculator
Standard Operating Procedures
SOP 11 – ROTARY DRILLING AND CORING

Updated January 9, 2004 SOP11-2
11.1.3 Handling and Sample Preparation
 Permanent markers (red, blue, and black or alternate colors)
 Core bags
 Chisel for breaking core
 Heavy aluminum foil
 Hand saw
 Masking tape
 Duct tape
 Core boxes

11.2 RECOVERING AND PHOTOGRAPHING
Once the core barrel has been retrieved from the borehole, it is essential that the procedures used
to handle and document the core be both efficient and complete. To minimize moisture loss and
other environmental effects, the core should be kept out of direct sunlight when possible and
samples should be sealed as soon as possible. The return from each core run should be
transferred to the V block so that the top (higher elevation) is always to the logger's and
photographer's left. The core should then be photographed promptly. Each photo should include
clear and visible markers (e.g., index cards) with the boring number, core run number depths at
the top and bottom of the run, date, and time. A bar scale should also be included in each photo.
For uniformity, the core should be photographed in lengths not exceeding about four feet.

11.3 MARKING THE CORE
After photographing, the core may be marked with two vertical marker stripes down its entire
length to establish an orientation benchmark or scribe line and to allow for the reassembly of the
core if the core pieces are somehow mixed up or dropped. A red stripe may be drawn on the
right side of the core (Red on Right) and a blue stripe may be drawn on the left side of the core
(the side closest to the logger with the bottom of the run on the logger's right). To ensure
consistency and efficiency, tape the red and blue markers together so that the core can be marked
simultaneously. Care should be taken to mark the scribe lines as straight as possible. Sections
chosen for laboratory analyses should not be marked. Depths should then be marked on the core
in black marker where possible. Intervals of core loss, when identifiable, can be replaced with a
core loss block (e.g., wood or Styrofoam) with the depths marked on the block. Some types of
Styrofoam may not accept marking and will require a label, such as masking tape. Otherwise, an
interval of appropriate length is left open at the end of each run and labeled as C–UN (core loss –
unknown depth).
Standard Operating Procedures
SOP 11 – ROTARY DRILLING AND CORING

Updated January 9, 2004 SOP11-3
11.4 TOTAL RECOVERY AND RQD
The total core recovery for that core run should be measured. The total recovery is defined as:
Total core recovery = (length of all core pieces recovered/total length drilled)
The total recovery should be noted in the proper field log column as a fraction, and if time
permits, a percentage. The field log also contains a column for noting the number and size of
core pieces. The Rock Quality Designation (RQD) of the core should then be determined.
The RQD is defined as:
RQD = (length of intact core pieces 4" in length) / total length drilled
Pieces shorter than 4 inches (10 cm) in length resulting from close fractures or weathering should
not be summed. Pieces broken during the drilling process or during handling ("mechanical
breaks") should be fitted together and considered as one piece. These features are usually
identifiable fresh breaks with a different character than natural discontinuities. The RQD values
of individual beds, structural domains, weakness zones, and etc. should be logged separately.

11.5 LOGGING CONVENTIONS
11.5.1 Lithologic Log Conventions
Mark each core run in the "run number" column on the log as a rectangular box the length of the
run. A vertical line should be drawn through the middle of the box. Intervals prepared for
laboratory analysis (see sample preparation below) should be marked as solid segments in the
core run symbol.
A standard macroscopic petrologic description (use Figure 11–2 as a guide) should be entered for
each rock type encountered. Descriptions should include the following information:
 Rock type – the predominant type should be written in upper case, adjectives in lower
case (see example log)
 Color – use of the Munsell color chart is recommended where pertinent
 Composition – identify important components and approximate percentages
 Texture – grain/crystal size, roundness, sphericity, voids, inclusions, etc.
 Weathering – include degree (fresh, slightly, moderately, highly, completely)
Standard Operating Procedures
SOP 11 – ROTARY DRILLING AND CORING

Updated January 9, 2004 SOP11-4
 Hardness – soft, moderately, medium, and extremely hard, based on scratch test with
pocket knife
 Fossils – occurrence (type) and abundance
 Any pertinent or unusual aspects.
Any variation within a rock type should be noted at the appropriate depth. The proper symbol
for the rock type should be drawn on the log in the "Lithologic Symbol". Abbreviations should
be used in written descriptions to increase efficiency, but must be defined in a key that can be
deciphered in the office. It is imperative that field logs be legible – write neatly! Use a scale of
1" = 5’ or smaller (1" = 1').
11.5.2 Fracture Log
The generic term for discontinuities without reference to genesis or mode of origin is "fracture."
A "joint" is defined as a fracture that has experienced dominantly opening movement normal to
the fracture plane. A "fault" is defined as a fracture for which movement parallel to the fracture
plane can be demonstrated. The term "fracture" should be used in the log description unless
sufficient evidence exists for a term describing its origin. Fractures should be recorded
graphically on the field log in the "Lithologic Symbol" column at the depths and orientations at
which they occur. Mechanical breaks should be shown as a jagged line and labeled "MB."
Fractures should be described in the lithology column at the depths at which they occur. This
description should include:
 Wall roughness – smooth or tough
 Fracture fillings – terms used to describe fracture fillings include
— clean – no fracture filling material
— stained – coloration of rock only, no recognizable filling material
— filled – recognizable filling material
The percentage of the filling material present and its composition should be noted in
the description. If possible, the separation distance between fracture walls should be
recorded as well (in mm).
 Slickensides – the occurrence of slickensides and their relative orientation should also
be noted.
 Fracture orientation – the orientation of fractures should be measured with a
protractor relative to the red core scribe line.

Standard Operating Procedures
SOP 11 – ROTARY DRILLING AND CORING

Updated January 9, 2004 SOP11-5
11.6 OPERATIONAL NOTES
For all sampling and coring operations, the log should be a complete chronology of drilling and
sampling operations within the hole, including delays. The log should contain equipment data,
including the type of core barrel and bit, and its length and diameter. In addition, the average
rotational speed, downward hydraulic pressure, and average rate of penetration should be noted.
Keep track of time (military or 24–hour clock) on the left–hand margin of the log at regular
intervals.

11.7 HANDLING AND SAMPLE PREPARATION
Once the core has been logged, intervals to be sampled should be selected and prepared. Once
the core piece to be sampled is identified, place it on a large sheet(s) of aluminum foil and wrap
it tightly. Be consistent with the position of the core each time you prepare a sample (e.g.,
always keep the lower depth or bottom to your right). Place the core in the plastic core bag in
such a way that the core is resting on one side seam of the bag and you are holding the bag by the
opposite side seam. There should be at least 3 inches of empty bag above the core. After tilting
the bag until the core slides all the way to the bottom of the bag, lay the bag down on a flat
surface with the seam you are holding away from you. Roll the core so that the empty side of the
bag is tightly wrapped around the core and air space is minimized. Double tape the core close to
the bottom with a continuous strip of masking tape. Then, grasp the top portion of the bag above
the core and, holding it upright; spin it until the bag top is tightly wound. Fold the twisted top
down and tuck it under the extra bag wrap, and then tape the core close to the top tightly so that
the twist doesn't come undone.
The end product should be airtight and relatively wrinkle–free to minimize entrapped air. With
the bottom to your right, label the sample with the job number, borehole, core run number, depth
interval, date, and your initials. Store the samples in a protected dark and, if possible, cool place.

11.8 CURATING CORE
After the samples have been prepared, the core should be boxed. If the core is to be bagged,
follow the same procedure as outlined above without using aluminum foil. For large core pieces,
use two bags placed on opposite ends. Mark bags appropriately. Core pieces that are too long to
fit into the core box should be broken carefully. If the core cannot be broken by hand, a well–
placed rap with a rock hammer or similar instrument should be used to break the core at the
desired location. The core should be placed in the box, starting in the upper left–hand corner
(long side of the box toward you) and with the bottom of the core in the lower right corner (just
as in reading a printed page). One box per core run should be used unless the top and bottom of
Standard Operating Procedures
SOP 11 – ROTARY DRILLING AND CORING

Updated January 9, 2004 SOP11-6
each run are clearly marked with blocks. Missing intervals and sampled intervals should be
replaced with appropriately marked blocks. The job number, borehole, core run number, depth
interval, date, your initials, and the depths at the beginning and end of each partition of the box
should be labeled on the underside of the lid. Once the core has been placed in the box, it is
helpful to take a picture of the box, including the inside of the lid, to provide a record of its
contents. Use duct tape to hinge the lid along the top long side of the box. The box itself should
be marked in case lids are accidentally switched or lost. One end of the box should be marked
with the job number, borehole, core run number, depth interval, date, and your initials. The other
end should be marked with the borehole number, core run number and depth interval to aid in
identification when stacked with other core boxes.
Chapter 10
GUIDELINES FOR
CORE LOGGING
These guidelines incorporate procedures and methods
used by many field offices and are appropriate for"standard" engineering geology/geotechnical log forms,
computerized log forms, and many of the modified log
forms used by various Bureau of Reclamation
(Reclamation) offices.
General
Introduction
This chapter describes the basic methods for engineering
geology core logging and provides examples and
instructions pertaining to format, descriptive data, and
techniques; procedures for working with drillers to obtain
the best data; caring for recovered core; and water testingin drill holes. The chapter also provides a reference for
experienced loggers to improve their techniques and train
others. Most of the discussions and examples shown
pertain to logging rock core, but many discussions apply
to soil core logging, standard penetration resistance logs,and drive tube sample logging.
Purpose, Use, and Importance of Quality Core
Logging
The ability of a foundation to accommodate structure
loads depends primarily on the deformability, strength,
and groundwater conditions of the foundation materials.
The remediation of a hazardous waste site can be
formulated only by proper characterization of the site.Clear and accurate portrayal of geologic design and
evaluation data and analytical procedures is paramount.
Data reported in geologic logs not only must be accurate,
FIELD MANUAL
250
consistently recorded, and concise, but also must provide
quantitative and qualitative descriptions.
Logs provide fundamental data on which conclusions
regarding a site are based. Additional exploration or
testing, final design criteria, treatment design, methods
of construction, and eventually the evaluation of structure
performance may depend on core logs. A log may present
important data for immediate interpretations or use, or
may provide data that are used over a period of years.
The log may be used to delineate existing foundation
conditions, changes over time to the foundation or
structure, serve as part of contract documents, and may
be used as evidence in negotiations and/or in court to
resolve contract or possible responsible party (PRP)
disputes.
For engineering geology purposes, the basic objectives of
logging core are to provide a factual, accurate, and concise
record of the important geological and physical character-
istics of engineering significance. Characteristics which
influence deformability, strength, and water conditions
must be recorded appropriately for future interpretations
and analyses. Reclamation has adopted recognized
indexes, nomenclature, standard descriptors and
descriptive criteria, and alphanumeric descriptors for
physical properties to ensure that these data are recorded
uniformly, consistently, and accurately. Use of alpha-
numeric descriptors and indexes permits analysis of data
by computer. These descriptors, descriptive criteria,
examples, and supporting discussions are provided in
chapters 3, 4, and 5.
Exploration should be logged or, as a minimum, reviewed
by an experienced engineering geologist. The logger
should be aware of the multiple uses of the log and the
needs and interests of technically diverse users. The
CORE LOGGING
251
experienced logger concentrates on the primary purposes
of the individual drill hole as well as any subordinate
purposes, keeping in mind the interests of others with
varied geological backgrounds including geotechnical
engineers, contract drillers, construction personnel, and
contract lawyers. An experienced logger tailors the log to
meet these needs, describing some seemingly minor
features or conditions which have engineering
significance, and excluding petrologic features or geologic
conditions having only minor or academic interest. Less
experienced loggers may have a tendency to concentrate
on unnecessary garnishment, use irrelevant technical
terms, or produce an enormously detailed log which
ignores the engineering geology considerations and
perhaps the purpose for completing the drill hole.
Adequate descriptions of recovered cores and samples can
be prepared solely through visual or hand specimen
examination of the core with the aid of simple field tests.
Detailed microscopic or laboratory testing to define rock
type or mineralogy generally are necessary only in special
cases.
Empirical design methods, such as the Rock Mass Rating
System Geomechanics Classification (RMR) and Q-system
Classification (Q), are commonly used for design of under-
ground structures and are coming into common use for
other structures as well. If these methods are used, the
necessary data must be collected during core logging.
If hazardous waste site characterization is the primary
purpose of the drilling, the log should concentrate on
providing data for that type of investigation.
Drilling and logging are to determine the in-place
condition of the soil or rock mass. Any core condition,
core loss, or damage due to the type of bit, barrel, or other
equipment used, or due to improper techniques used in
FIELD MANUAL
252
the drilling and handling processes should be described.
Such factors may have a marked effect on the amount and
condition of the core recovered, particularly in soft,
friable, weathered, intensely fractured materials or zones
of shearing. Geologic logs require the adequate
description of materials; a detailed summary of drilling
equipment, methods, samplers, and significant
engineering conditions; and geologic interpretations.
Complete geologic logs of drill holes require adequate
descriptions of recovered surficial deposits and bedrock,
a detailed summary of drilling methods and conditions,
and appropriate physical characteristics and indexes to
ensure that adequate engineering data are available for
geologic interpretation and analysis.
Format and Required Data for the
Final Geologic Log
Organization of the Log
The log forms are divided into five basic sections: a
heading block; a left-hand column for notes; a center col-
umn for indexes, additional notes, water tests and
graphics; a right-hand column for classification and
physical conditions; and a comments/explanation block at
the bottom. Data required for each column are described
in the following discussion and the referenced example
logs. Log DH-123, figure 10-1, and log B-102, figure 10-2,
are the most complete and preferred examples; other
variations are presented but in some cases are not
complete.
Heading
The heading block at the top of the form provides spaces
for supplying project identifying information, feature,
CORE LOGGING
253
Figure 10-1.—Drill hole log, DH-123, sheet 1 of 2.
FIELD MANUAL
254
Figure 10-1.—Drill hole log, DH-123, sheet 2 of 2.
CORE LOGGING
255
Figure 10-2.—Drill hole log, B-102, for Standard
Penetration Test, sheet 1 of 3.
FIELD MANUAL
256
Figure 10-2.—Drill hole log, B-102, for StandardPenetration Test, sheet 2 of 3.
CORE LOGGING
257
Figure 10-2.—Drill hole log, B-102, for Standard
Penetration Test, sheet 3 of 3.
FIELD MANUAL
258
hole number, location, coordinates, elevation, bearing and
plunge of hole, dates started and completed, and the
name(s) of the person(s) responsible for logging and re-
view. Locations should preferably be in coordinates
unless station and offset are all that is available.
Provide both coordinates and station and offset if
available. The dip or plunge of the hole can be the angle
from horizontal or from vertical, but the reference point
should be noted on the log. Spaces for depth to bedrock
and water levels are also provided. All this information
is important and should not be omitted. Below the
heading, the body of the log form is divided into a series
of columns covering the various kinds of information
required according to the type of exploratory hole.
Data Required for the "Drilling Notes" Column
Data for the left-hand column of all drill hole logs are
similar whether for large-diameter sampling, Standard
Penetration Tests, rock core, or push-tube sampling logs.
These data are field observations and information
provided by the driller on the Daily Drill Reports.
Examples are provided for some of these data headings;
a suggested guideline and preferred order is presented in
the following paragraphs but may differ depending on the
purpose and type of exploration. Headers for data can
indicate whether depths are in feet (ft) or meters (m),
eliminating the need to repeat "ft" or "m" for each interval
entry. An example of the Drilling Notes column is
provided on figures 10-1 through 10-4.
General Information.—This includes headers and data
for the hole purpose, the setup or site conditions, drillers,
and drilling and testing equipment used.
CORE LOGGING
259
Figure 10-3.—Drill hole log, DH-SP-2, sheet 1 of 2.
FIELD MANUAL
260
Figure 10-3.—Drill hole log, DH-SP-2, sheet 2 of 2.
CORE LOGGING
261
Figure 10-4.—Drill hole log, SPT-107-2, sheet 1 of 3.
FIELD MANUAL
262
Figure 10-4.—Drill hole log, SPT-107-2, sheet 2 of 3.
CORE LOGGING
263
Figure 10-4.—Drill hole log, SPT-107-2, sheet 3 of 3.
FIELD MANUAL
264
1. Purpose of hole — Includes reason for drilling
the hole, such as foundation investigation, materials
investigation, instrumentation, sampling, or testing.
2. Drill site or setup — Includes general physical
description of the location of the drill hole.
Information on unusual setups, such as adjacent to
a stream, or drilled from a barge, gallery, or adit,
may help understand the unusual conditions.
3. Drillers — Names of drillers may be significant
for reference or for evaluating or interpreting core
losses, drilling rates, and other drilling conditions.
4. Drilling equipment —
•Drill rig (make and model)
•Core barrel(s), tube(s), special samplers (type
and size)
•Bits (type and size)
•Drill rods (type and size)
•Collar (type)
•Water test equipment (rod or pipe size, hose
size, pump type and capacity, and relative
position and elevation of pressure gauges or
transducers), packers (type—mechanical or
pneumatic)
Example: Skid-mounted Sprague and Henwood
Model 250. NWD3 bottom discharge bit with a
5-ft (1.5-m), split-tube inner barrel. 5-ft (1.5-m)
NW rods. Water tested with NX pneumatic
CORE LOGGING
265
packer No. 12 with 1-1/4-inch (in) (32-millimeter
[mm]) pipe, Bean pump with 35-gallons per
minute (gal/min) (159 liters per minute)
maximum volume, and 1-in (25-mm) water
meter. (Water testing equipment can be a
separate heading if desired.)
Drilling Procedures and Conditions.—These headers
and data should include methods, conditions, driller's
comments, and records for water losses, caving, or casing.
1. Drilling methods — Synopsis of drilling, sam-
pling, and testing procedures, including procedures
and pressures for drive or push tubes used through
the various intervals of the hole.
2. Drilling conditions and driller's comments —
Note by interval the relative penetration rate and
the action of the drill during this process (i.e., 105.6-
107.9: drilled slowly, moderate blocking off, hole
advancing 15 minutes per foot [.3 meter]). Unusual
drilling conditions should be summarized. Changes
in drilling conditions may indicate differences in
lithology, weathering, or fracture density. The
geologist needs to account for variations in driller's
descriptions; each driller may describe similar
conditions with different adjectives or percentage
estimates. Any other comments relative to ease or
difficulty of advancing or maintaining the hole
should be noted by depth intervals. Drillers'
comments need to adequately describe conditions
encountered while advancing the hole. Statements
such as "normal drilling" or "no problems
encountered" are not useful.
Differences in drilling speeds, pressures, and
penetration rates may be related to the relative
FIELD MANUAL
266
hardness and density of materials. Abrupt changes
in drilling time may identify lithologic changes or
breaks and also may pinpoint soft or hard interbeds
within larger units. Often, these may be correlated
with geophysical logs. If the driller provides useful
and accurate records of drilling conditions and
procedures, an accurate determination of the top and
bottom of key marker horizons can be made even
without core.
Drilling progress should be recorded while drilling;
recovery can be improved by relating recovery to
optimum pressures and speeds, as well as providing
data for interpretation. For each run, the driller
should record the time when starting to drill and
when stopping to come out of the hole. Most of these
drilling progress data are qualitative rather than
quantitative values. Controlling factors are not only
the type of materials encountered but also may be
mechanical or driller variables. These variables may
include type and condition of the bit, rotation speed,
drilling fluid pressure, etc. THE PURPOSE OF THE
BORING IS TO OBTAIN THE HIGHEST QUALITY
CORE AND MOST COMPLETE RECOVERY AND
INFORMATION, NOT JUST FEET PER HOUR OR
SHIFT.
3. Drilling fluid — Type and where used (including
drilling fluid additives). This may be combined with
or discussed under the heading, drilling methods.
4. Drilling fluid return — Include interval/percent
return. Drilling fluid return may be combined with
color.
5. Drill fluid color — Include interval/color.
CORE LOGGING
267
6. Caving conditions — Intervals of cave with ap-
propriate remarks about the relative amount of
caving are to be noted. When possible, report the
actual caving interval rather than the depth of the
hole.
7. Casing record — Casing depth is the depth of
casing at the start of the drilled interval (see the
example below).
8. Advancement (push-tube or Standard
Penetration Test (SPT) applications) — Include
depth/ interval sampled.
9. Cementing record — Note all intervals
cemented and if intervals were cemented more than
once. This information may be combined with the
casing record, as shown below:
Example of casing and cementing record:
Interval drilled
(feet)
Size
(inch)
Casing depth
(feet)
0.0-2.3 6 Cs 0.0
2.3-4.5 6 Cs 2.0
4.5-9.2 6 Cs 4.0
9.2-15.3 NxCs 8.0
15.3-18.7 NxCs 15.0
18.7-33.2 Cmt 12.1-18.7 Cmt
Hole Completion and Monitoring Data.—Data shown
in this section of the left-hand column include hole
completion, surveys, water levels, drilling rates or time,
and reason for hole termination.
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268
1. Borehole survey data — Include if obtained.
Example of survey data:

Depth Bearing Plunge
59
79
99
119
Average
S 72EW
S 75E W
S 72E W
S 72E W
90E1
90E
89E
89E
89E
1 E = degrees.
2. Water level data — Note depths and/or eleva-
tions, water quantities, and pressures from artesian
flows. Water levels or flows should be recorded
during hole advancement, between shifts, or at the
beginning or end of a shift, but definitely should be
recorded at completion of the hole and periodically
thereafter. It may be advantageous to leave space or
provide a note to refer the user to additional readings
provided elsewhere on the log for subsequent
measurements. Computer generated logs allow
convenient updating of water levels long after the
hole is completed.
Examples of drill hole logs illustrate optional format
and subsequent readings. Examples of how to record
data are:
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269
Date
1981
Hole depth
(feet)
Depth to
water
(feet)
11-02 25.0 6.0
Bailed 100 gal:
Level before
Level after
6.0
21.0
or:
Date
Hole depth
(feet)
Depth to
water
(feet)
11-03-81 25.0 15.0
11-04-81 40.0 29.0
01-05-82 95.2 7.0
01-15-82 95.2 Flowing 25 gal/min
02-03-82 95.2 Flowing 5 gal/min
at 5 pounds per
square inch
(lb/in2)
3. Hole completion — Indicate how hole was com-
pleted or backfilled; if jetting, washing, or bailing
was employed; depth of casing left in hole or that
casing was pulled; location and type of piezometers;
location, sizes, and types of slotted pipes (including
size and spacing of slots) or piezometer risers; type
and depth of backfill or depths of concrete and/or
bentonite plugs; location of isolated intervals; and
elevation at top of riser(s). Hole completion can be
shown graphically (see figure 10-5).
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270
Figure 10-5.—Drill hole log, DH-DN/P-60-1, sheet 1 of 3.
CORE LOGGING
271
Figure 10-5.—Drill hole log, DH-DN/P-60-1, sheet 2 of 3.
FIELD MANUAL
272
Figure 10-5.—Drill hole log, DH-DN/P-60-1, sheet 3 of 3.
CORE LOGGING
273
4. Reason for hole termination — State whether
the hole reached the planned depth or reason why
the hole was stopped short.
5. Drilling time — Total time, setup time, drilling
time, and downtime should be recorded on drillers'
daily sheets and should also be recorded on the drill
log. These records are essential for determining
exploration program costs.
Center Columns of the Drill Log
Computer Logs.—Computer-generated logs offer several
options for the content and format of the log such as
permeability, penetration resistance, or rock properties
which have some differences in format. Examples of each
are shown in figures 10-2 through 10-5.

Standard Geologic Log Form.—The following
discussion pertains to the center columns for the standard
Reclamation log (form 7-1337). The columns shown on
all figures are self-explanatory. The columns can be mod-
ified or new columns added to the existing log form for
recording appropriate indexes or special conditions.
The percolation tests (water-pressure tests) column
should record the general information of the tests.
Additional data may be recorded on "water testing" log
forms or drillers' reports.
Type and size of hole, elevation, and depth columns are
self-explanatory.
Core recovery should be recorded in percent of recovery
by run. Although desirable, core recovery does not
necessarily require a visual graph. Core recovery should
be noted carefully by the driller for each run on the daily
FIELD MANUAL
274
drill reports; however, this column should be the record
of those measurements determined by the geologist
during logging. Measuring the core while in the split
tube or sampler, if possible, will produce the most
accurate recovery records.
A hole completion column may be added which
graphically portrays how the hole was completed. If used,
an explanation of the graphic symbols should be provided
on the log form.
Rock quality designation (RQD) should be reported by
core run. RQD should be included on the log in graph or
tabular form regardless of the type project. RQD is used
in almost any engineering application of the hole data.
Most contractors are interested in RQD as an index of
blasting performance, rippability, and stability. RQD is
described and explained in chapter 5.
A lithologic log or graphic column is helpful to quickly
visualize the geologic conditions. Appropriate symbols
may be used for correlation of units, shear zones, water
levels, weathering, and fracturing (see figure 10-1).
The samples and testing column should include locations
of samples obtained for testing and can later have actual
sample results inserted in the column, if the column is
enlarged.
Modifications to Standard Log Form.—Modifications
or adaptations of the center columns are permissible and,
in some instances, encouraged. Examples are:
1. The use of a continuation sheet for longer drill
logs saves time and is easier to type. The sheets may
have only one column to continue the right-hand
narrative, or may be divided into two or more
CORE LOGGING
275
columns. See sheets 2 and 3 for drill hole SPT-107-2,
figure 10-4, for an example; also see sheet 3 of 3 for
drill hole DH-DN/P-60-1, figure 10-5.
2. The center column may be modified to portray ad-
ditional data such as hole completion, various
indexes, alphanumeric descriptors, or laboratory test
data.
Standard penetration test hole SPT-107-2,
figure 10-4, is a modified penetration resistance log
which shows laboratory test results; a percent
gravel/percent sand/ percent fines column; liquid
limit/plasticity index (LL/PI) column, a field moisture
column, and other modifications. Drill hole DH-SP-2,
figure 10-3, has columns for reporting field density
test results, moisture, porosity, percent saturation,
percent fines/percent sand, LL/PI, and laboratory
classification.
3. Another modification, shown on DH-SP-2,
figure 10-3, is a drawing showing the location of the
hole in relation to the structure being explored.
Diagrams or graphs, such as water levels, may
illustrate data better than a column of figures.
Required Data and Descriptions for the Right-
Hand "Classification and Physical Condition"
Column
General.—An accurate description of recovered core and
a technically sound interpretation of nonrecovered core
are the primary reasons for core logging. The logger
needs to remember that any interpretation, such as a
shear, must be based on observed factual data. The
interpreted reason for the core loss is given, but usually
FIELD MANUAL
276
it is best to define the area of core loss as the interval
heading. For example:
99.4. to 101.6: No Recovery. Interpreted to be in-
tensely fractured zone. Drillers reported blocking off,
core probably ground up during drilling.
103.4 to 103.7: Open Joint?. Drillers reported 0.3-ft
drop of drill rods during drilling and loss of all water.
Joint surfaces in core do not match.
0.7 to 11.6: Silty Sand. Poor recovery, only 6.2 ft
recovered from interval. Classification based on re-
covered material and wash samples.
0.9 to 3.2: Rockbitted. No samples recovered.
(Usually this would be subheaded under a previous
description, inferring the materials are the same as
the last recovered).
Descriptions of Surficial Deposits.—Surficial deposits
such as slope wash, alluvium, colluvium, and residual soil
that are recovered from drill holes are described using
USBR 5000 and 5005. If samples cannot be obtained,
then description of the cuttings, percent return and color
of drilling fluid, drilling characteristics, and correlation to
surface exposures is employed. Always indicate what is
being described—undisturbed samples, SPT or wash
samples, cuttings, or cores. Descriptors and descriptive
criteria for the physical characteristics of soils must
conform to the established standards. Chapter 11
provides guidelines for soil and surficial deposit
descriptions.
Extensive surficial deposits usually are described using
geologic and soil classifications. Where surficial deposits
are very shallow and not pertinent to engineering
applications for design or remediation or where geologic
CORE LOGGING
277
classification such as landslides or talus is preferable,
units may be given genetic or stratigraphic terms only.
For example, Quaternary basin fill, recent stream
channel deposit, Quaternary colluvium, zone 3
embankment, and random fill may be described
generally; or these may be unit headings with group
name subheadings. The format is:
Geologic and group name. i.e., Alluvium, (sandy
silt). Field classification in parentheses if classified,
refer to chapters 3 and 11 for exceptions.
Classification descriptions. Additional
descriptors (particle sizes, strength, consistency,
compactness, etc., from the USBR 5000 and 5005
standards descriptive criteria).
Moisture. (dry to wet).
Color.
If cores or disturbed samples are not available, describe
as many of the above items as can be determined from
cuttings, drill water color, drilling characteristics,
correlation to surface exposures, etc. Remember that for
rockbitted, no recovery, or poor recovery intervals, a
classification and group name should be assigned as a
primary identification.
Description of Rock.—Description of rock includes a
rock unit name based on general lithologic characteristics
followed by data on structural features and physical
conditions. Bedrock or lithologic units are to be delineated
and identified, not only by general rock types but by any
special geological, mineralogical features with
engineering significance, or those pertinent to
interpretation of the subsurface conditions.
FIELD MANUAL
278
Any information which is characteristic of all of the rock
units encountered normally is included under the main
heading, producing more concise logs. Differences can be
described in various subheadings. Rock core is to be
described in accordance with descriptors and descriptive
criteria presented in chapters 4 and 5. A suggested
format is:
1. Rock name — A simple descriptive name,
sufficient to provide others with possible engineering
properties of the rock type; may include geological
age and/or stratigraphic unit name.
2. Lithology (composition/grain sizes/texture/
color) — Give a brief mineralogical description.
Describe grain shape and size or sizes and texture
using textural adjectives such as vesicular,
porphyritic, schistose. (Do not use petrographic
terms such as hypidiomorphic, subidioblastic). Other
pertinent descriptions could include porosity,
absorption, physical characteristics that assist in
correlation studies, and other typical and/or unusual
properties. Provide the wet color of fresh and
weathered surfaces.
Contacts should be described here also. If the
contacts are fractured, sheared, open, or have other
significant properties, the contacts should be
identified and described under separate subheadings.
3. Bedding/foliation/flow texture — Provide a
description of thickness of bedding, banding, or
foliation including the dip or inclination of these
features.
4. Weathering/alteration — Use established de-
scriptors which apply to most of the core or use
individual subheadings. For alteration other than
CORE LOGGING
279
weathering, use appropriate descriptors. These may
or may not be separate from weathering depending
upon rock type and type of alteration. Also, include
slaking properties if the material air or water slakes.
(Weathering may be used as first or second order
headings for some logs.)
5. Hardness — Use established descriptors.
6. Discontinuities — These include shears, joints,
fractures, and contacts. Discontinuities control or
significantly influence the behavior of rock masses
and must be described in detail. Detailed discussions
of indexes and of descriptive criteria, descriptors, and
terminology for describing fractures and shears are
provided in chapter 5 and 7.
Fractures or joints should be categorized into sets if
possible, based on similar orientations, and each set
should be described. When possible, each set should
be assigned letter and/or number designations and
variations in their physical properties noted by depth
intervals. Significant individual joints also may be
identified and described. Physical measurements
such as spacing and orientation (dip or inclination
from core axis), information such as composition,
thickness, and hardness of fillings or coatings;
character of surfaces (smooth or rough); and, when
possible, fracture openness should be recorded. In
drill core, the average length between fractures is
measured along the centerline of the core for
reporting any of the fracture indexes. However,
when a set can be distinguished (parallel or
subparallel joints), true spacing is measured normal
to the fracture surfaces.
FIELD MANUAL
280
Description of Shears and Shear Zones.—Shears and
shear zones should be described in detail, including data
such as the percentage of the various components (gouge,
rock fragments, and associated features such as dikes and
veins) and the relationship of these components to each
other. Gouge color, moisture, consistency and
composition, and fragment or breccia sizes, shape, surface
features, lithology, and strengths are recorded. The
depths, dip or inclination, and true thickness, measured
normal to the shear or fault contacts, also must be
determined, if possible, along with healing, strength, and
other associated features. A thorough discussion of
shears and shear zones is contained in chapter 5.
Description of Core Loss.—The significance of core loss
is often more important than recovered core. Lost core
may represent the worst conditions for design concepts, or
it may be insignificant, resulting from improper drilling
techniques or equipment. Core losses, their intervals,
and the interpreted reason for the loss should be recorded
on the log.
Written Description Form.—The written description
for physical conditions consists of main headings,
indented subheadings, and text which describes the
important features of the core. Headings and indented
subheadings divide the core into readily distinguishable
intervals which are pertinent to an engineering geology
study. Assigned unit names should correlate with those
unit names used for surface mapping. These headings
may describe portions of the core or the entire core,
depending on how well the headings encompass overall
characteristics. Items characteristic of the entire core in
one hole may be stated under the major heading;
however, in other holes, this same information may have
to be broken out into various subheadings because it is
not applicable to the entire core. In this discussion,
CORE LOGGING
281
several logs are referenced as examples. These logs do
not necessarily reflect the established standards, and
each may be deficient in some format or context; they are
existing logs which are included as examples of different
situations which may be encountered. A discussion of
headings follows:
1. Main headings — The main heading usually
divides surficial deposits from bedrock. However,
other methods are also acceptable, for example, the
summary log in figure 10-5.
2. First order heading — The first order headings
may be based on weathering or lithology. When the
initial rock type exhibits more than one weathering
break or the lithologic properties are most
significant, lithology would be the first order
heading. Weathering may be used as first order
headings where significant. If a weathering break
coincides with a lithologic break, or only one
weathering break is present, they may both be
included in the main heading. Depending on
lithologies present, for example, if there is only one
rock type, the first order headings may be based on
fracturing. Lithology, weathering, or fracturing can
also be the subject of the first order heading. In
certain circumstances, a shear or shear zone or other
feature could be given a first order or any lower order
heading in order to emphasize a feature’s presence or
importance. The arrangement which will result in
the simplest log is usually the best and should be
used. The following examples illustrate the use of
first, second, and third order headings. These
examples are not intended to represent examples of
complete logs.
An example in which weathering is preferred as the
first order heading is:
FIELD MANUAL
282
0.0-5.0: SLOPE WASH (main heading).—General de-
scription could include the total description of the
unit.
5.0-200.0: PALEOZOIC CALAVERAS GROUP (main
heading).
5.0-100.3: Moderately Weathered (first order
heading based on weathering; descriptions of
weathering applicable to all lithologies could be
presented here).
5.0-10.9:Basalt
10.9-20.1:Limestone
20.1-50.3:Shale
50.3-100.3:Sandstone
100.3-150.0:Slightly Weathered
100.3-120.2:Sandstone
120.2-150.0:Shale
150.0-200.6:Fresh Shale
An example in which lithology is preferred as the
first-order subheading is:
0.0-5.0: SLOPE WASH (main heading).—General de-
scription, could include the total description of the
unit.
5.0-200.6: PALEOZOIC CALAVERAS GROUP (main
heading).—General description applicable to all
lithologies.
5.0-100.3: Sandstone (first order heading based on
lithology)
5.0-10.2: Intensely weathered
CORE LOGGING
283
10.2-40.1: Moderately weathered
40.1-80.2: Slightly weathered
80.2-100.3: Fresh
100.3-150.1: Fresh Shale (first order heading which
combines weathering and lithology)
150.1-200.6: Fresh Diabase
3. Second order heading — The second order
heading and the associated description contain the
char-acteristics of the rock that are unique to an
interval that is not described in the main and first
order headings. The second order heading usually is
based on weathering if the first order heading is
based on lithology. If the first order heading is based
on weathering, the second order heading would usu-
ally be based on lithology. Fracture data can be
described here if similar throughout the interval; if
not, divide fracture data into third order headings.
4. Third order heading — The third order heading
is usually based on fracture data, subordinate
features, variations in lithology, etc. This includes
variations of rock quality within a certain lithology
due to shears, joints, bedding or foliation joints, or
other discontinuities. Core recovery lengths are an
indicator of fracturing and should be described under
this heading, as in the interval from 87.2 to 101.2 in
DH-123 figure 10-1. If the fractures are mainly
prominent joint sets or other discontinuities, the
spacing and orientation of individual sets, along with
the overall fracture characteristics, should be noted.
FIELD MANUAL
284
5. Additional indentations — Additional
indentations usually are used to describe important
addi-tional subordinate features, such as veins or
veinlets, variations in lithology, shears, and zones of
non- or poor recovery.
In summary, any information consistent throughout
a higher order heading, but usually included in a
lower one, should be described in the higher order
heading to prevent repetition.
Data Required for the Comments/Explanation
Block
The comments/explanation block at the bottom of the log
form is used for additional information. This may include
abbreviations used, gauge height for packer tests, and
notes. The hole start and completion date should be in
the heading, as well as the date logged. Revision dates of
the log should be noted to ensure that the most recent
version of the log can be identified. (Date logged and any
subsequent revision dates should be entered in this
block). The computer log file name can be recorded in
this block.
Method of Reporting Orientation of Planar
Discontinuities and Structural Features
True dips can be measured directly in vertical holes. The
dips of planar features in vertical holes are recorded as
"dips 60E”or "60E dip" (see drawing 40-D-6499, figure 5-9).
True dip usually is not known in angle holes; and,
orientation is measured from the core axis and called
inclination, i.e., "Joints are inclined 45E from the core
axis" (figure 5-9). If dips are known from oriented core or
other surveys, dips may be recorded instead of inclination
CORE LOGGING
285
in angle holes. Figure 5-9 demonstrates how misinter-
pretations can occur; the inclination of a joint in the core
from a 45E inclined angle hole can be interpreted as a
horizontal joint or as a vertical joint by rotating the core.
Core Recovery and Core Losses
Descriptions of core in the Classification and Physical
Condition column should describe the recovered core, not
only by physical measurements (maximum, minimum,
and mostly range or average), but should identify and
include the interpretation for any core losses, especially
if the losses are thought to represent conditions different
from the core recovered. Designers and other users of the
completed log can incorporate into their design all the
factual data that are seen and recorded. What is not seen
or reported (core losses) is more difficult to incorporate
into the design and may well be the most significant
information. Also, core losses and interpretations of the
reasons for their loss are significant engineering data
that may correlate open joints, soft zones, or shears from
boring to boring or from surface features to the
subsurface explorations.
Core losses can result from three generalized conditions:
inaccurate measurements by the drillers; poor drilling
techniques, equipment, and handling; or geologic
conditions. The geologist, using the depth of hole,
recovered core, observations of the core, and drillers
observations, is the individual to make interpretations of
the core loss. All core should be measured by the logger.
If using a split-tube barrel, the core should be measured
while in the barrel and always after core segments are
fitted together (using the midpoint of core ends). Unac-
countable losses should be reconciled, and the location of
the loss determined.
FIELD MANUAL
286
Tape checks or rod checks are the most reliable and pre-
ferred methods for knowing the exact location of geologic
conditions (top of each run is known with certainty) and
where losses occur. All core runs should be measured and
recorded; gains and losses can be transferred to adjacent
runs and cancel out each other during the process of
determining where the core loss is located. Inaccurate
drillers’ measurements, or locations where portions of the
previously drilled interval was left in the hole (pulled off,
or fell back in and redrilled), can be determined by
examining and matching the end and beginning of each
core run to see if they fit together or show signs of being
redrilled. Gains may be attributed to pulling out the
bottom of the hole, mismeasurement, recovering core left
in the hole from the previous run, or recovery of
expansive, slaking, or stress relieving materials.
Where unaccountable losses occur, the examination of
core to determine the reason for that loss is critical. Poor
drilling methods (excessive pressure, speed, excessive
water discharge from the drill bit, not stopping when fluid
return plugs), inaccurate measurements, or geologic
conditions responsible for core losses should be
determined. Core may have spun in the barrel after
blocking; an intensely fractured zone may have been
ground up; or a shear zone, open joint(s), solution cavity,
or joint fillings may have been washed away. Geologic
interpretation of the core loss is based on examining
recovered core and the fractures present in the core. Drill
water losses and color or changes in the drilling
conditions noted by the driller may suggest an
interpretation of the core loss. Where losses occur near a
recovered clay "seam," clay coats fracture surfaces,
slickensides and/or breccia and gouge are present, the
core loss may be interpreted as a shear or shear zone.
The description should include all the factual
information—discontinuity surface orientations,
slickensides, coatings, gouge and/or fractures; and the
CORE LOGGING
287
interpretation that the loss occurred in a shear.
Depending on the confidence in the interpretation based
on the observed conditions, the description can be given
as "shear," or "shear?," or "probable shear zone." When a
portion of a shear zone has been lost during drilling, the
no recovery zone should be described as part of the shear
and the loss or part of the loss included in the shear's
thickness.
Samples
If the geologist selects representative or special samples
for laboratory testing, an appropriate space should be left
in the core box to ensure that when logs are reviewed or
photographs are taken, core recovery is not misleading.
Either filler blocks or a spacer which indicates the top
and bottom depths of the sample and a sample number
can be used to fill the sample space. For N-size cores, a
length of 2- by 2-inch (50- by 50-mm) block or other
spacers that fill the tray work well. These blocks also
should be used to separate core runs. The lettering on
the blocks should be easily readable at a distance. Spray
painting the blocks white or yellow and lettering them
with black waterproof pens enhances visibility and
legibility. The sample interval, and sample number if
desired, must be recorded in the Samples for Testing
column on the log. Portions of the core may be preserved
as representative samples or to protect samples from
slaking or other deterioration.
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288
Core Photography
General Photographic Methods
Transmittal of core photographs with the final logs is rec-
ommended. The photos may be included in the data
package or as an appendix to the data report. Cores
should be photographed while fresh. Before and after
photographs of materials that slake or stress-relieve are
recommended. The importance of photographing the core
before it has been disturbed in transit and before its
moisture content has changed cannot be overemphasized.
If proper precautions during transport are followed, and
the core is logged in a timely manner, reasonably good
photographs can be obtained away from the drilling site.
This permits the labeling of core features, if desired.
If possible, cores should be photographed in both color
and black and white at 8- by 10-inch (200- by 250-mm)
size. Black and white photographs do not degrade over
time like color photographs. Core photographs should be
submitted with the final logs in the geology data report;
color photographs are best for data analysis.
Many methods are employed for photographing core.
Each box of core can be photographed separately as the
box is first filled or three or more boxes can be
photographed at a time. There are advantages to both
procedures:

•Greater detail and photographs depicting fresher
conditions are the major advantages of photo-
graphing each box individually.
•When photographing several boxes at a time,
transitional features, changes in weathering orfracturing, or large shear zones can be seen in one
photograph.
CORE LOGGING
289
The best method is a combination of the two. Pictures of
individual boxes at the drill site and later pictures of the
entire hole are the best of two worlds.
Individual Box Photography
Any portion of core that is in danger of altering or disag-
gregating because of slaking or "discing" due to stress
relief, expansion, or shrinkage due to changes in moisture
or confinement because of down time, ends of shifts, or
weekends must be boxed and photographed. Under these
circumstances, the core should be photographed while at
or near the material natural condition (even if a box is
only partially filled).
Each photograph should be taken from approximately the
same distance so that the scale of each photograph is
identical. The box should fill the frame of the camera,
thereby obtaining the highest quality resolution or core
detail, and the camera should be held as close to normal
to the core as possible. A tripod should be used if
possible. Tilting the core box and, if necessary, standing
in a pickup bed or other vantage point may be helpful.
Most core boxes can be tilted about 70 to 80E before any
core is in danger of spilling out, so very little additional
height is required. A simple 2- by 4-foot (0.6- by 1.2-m)
wood frame may be constructed, or the core box may be
leaned against a tool box, pickup tailgate, or other stable
object. A Brunton compass can be used to ensure that the
box and the camera are placed at a consistent, uniform
angle. Shadows should be eliminated as much as
possible.
All core should be photographed both wet and dry. In hot
or dry weather, the unphotographed boxed core should be
covered by moist cloth. When ready to photograph, any
dry zones should be touched up using a wet cloth or
FIELD MANUAL
290
paintbrush. In extremely hot weather, the boxed core can
be sprayed or sprinkled with water. A water hose, garden
sprayer, or spray bottle works well for this operation.
Wait for the water to be absorbed so that there is no
objectionable sheen or glare-producing film of water on
the core at the instant of film exposure.
A labeled lid, letter board, or another frame which shows
feature, drill hole number, photograph, or core box
number, and depths of the top and bottom of the cored
interval should be included in the photograph. A scale in
feet and/or tenths of a foot or meters is helpful.
Photographing Multiple Boxes
As soon as possible after the core is removed from the
barrel and boxed, the core should be photographed. To
facilitate the photography, construct a frame capable of
supporting three or more boxes at a time for use at the
drill yard or core storage yard. Photograph the core dry
then spray with water to bring back the natural moisture
color. The same precautions about glare referred to
previously should be followed.
A frame which shows the project, feature, hole number,
box __ of __boxes, and from—to, as a minimum, should be
used for the photograph. Other optional but
recommended entries may include date photographed,
and a scale.
Special Circumstances
Special photography such as closeups of shear zones or
other special features may be worthwhile. When these
photographs are taken, a common object or scale should
be included to provide the viewer with relative or actual
dimensions.
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291
When cores are coated with drill mud, a brush, wet rag,
or pocket knife should be used to wash or scrape off the
mud so that materials are their natural color and features
of the core are not obscured. This step obviously must be
taken prior to logging the material.
Photograph Overlays
Acetate or mylar overlays on photographs of core can help
interpretation of exposed features. Details shown may
include labels for shears, weathering, lithologies, or items
of special interest. Other items that may be shown on
overlays are joint sets, and they may be coded by an alpha
or numeric character or by colored ink.
Equipment Necessary for
Preparing Field Logs
The following equipment or supplies are necessary for
adequately preparing geologic logs:
Core recovery sheets and rough log forms or
computer data sheets.—For recording core recovery
and maintaining accurate depth measurements for
determining core loss intervals.
Drillers' reports.—Daily drill reports (figure 10-6) to
check measurements for core recovery, identifying
changes in condition or contacts in intervals of poor
recovery, determining reasons for core loss, and
evaluating openness of fractures.
Knife.—Core hardness/strength characteristics;
cleaning or scraping drill mud from core to allow
logging and measurement of core recovery.
Hammer.—Core hardness/strength characteristics.
FI
E
L
D

M
A
N
U
A
L
29
2
Figure 10-6.—Daily drill report.
CORE LOGGING
293
Tape measure or folding ruler (engineering scale
with hundredths of feet or metric as appropriate).—
Recovery measurements, thickness of units, shears
and fillings, and spacing of fractures.
Protractor.—Measuring orientation of contacts,
bedding and foliation, and fracture orientation.
Hydrochloric acid.—Mineral or cementing agent
identification (3:1 distilled water to acid).
Hand lens.—Mineral or rock identification, minimum
10X.
Marking pen.—Waterproof ink for marking core for
mechanical breaks, depth marks on core, sample
marking.
Paintbrush and/or scrub brush, and water.—For
cleaning core and for identifying wet color and
incipient fractures.
Color identification charts (Munsel Color System or
American Geological Institute Rock Color Chart).
Filler block (spacer) material.—For identifying non-
recovery intervals and location of samples and for
recording drill depths.
Sample preparation materials.—Wax, heater,
container, brush, cheese cloth, etc.
Rock testing equipment.—Schmidt hammer, point
load apparatus, pocket penetrometer or torvane.
FIELD MANUAL
294
Instruction to Drillers, Daily Drill Reports, and
General Drilling Procedures
Communication between the geologist and driller is
extremely important. Establishment of lines of
communication, both orally and in writing, is key to a
successful exploration program.
The role of the geologist in the drilling program is as an
equal partner with the driller at the drill site.
Establishment of this partnership at the beginning of the
drilling program will result in better data. Failure to
establish a good working relationship with the drill crew
often results in unanswered questions and a poor quality
end product. One way to establish good working rapport
is to keep the drillers informed and to plan with them.
Drill Hole Plan
A suggested method for ensuring that a clear
understanding of what the drilling requirements and
expectations are from the drill hole is the preparation of
a drill hole plan. The plan is prepared prior to starting
the hole and after the geologist has used available
interpretive data and has determined whether special
testing and procedures or deviations in standard practice
are required. This document provides the driller with
information about safety, special site conditions, purpose
of the hole, procedures to be followed, water testing
requirements, materials expected to be recovered, any
special sampling or geophysical testing required, and hole
completion requirements.
Guidelines for Drillers
The following guidelines provide a framework for
preparing written instructions for drill crews or for
CORE LOGGING
295
contract drill specifications. Also, the guidelines serve to
help geologists correct poor drilling procedures, collect
additional data, or improve core handling and logging.
Drill Setup.—To ensure that drill holes are completed at
the desired location and along the correct bearing and
plunge, the use of aiming stakes and a suitable device for
measuring angles should be provided by the geologist and
used by the drill crews. Drillers should use aiming stakes
set by the geologist or survey crew for the specified
bearing of the drill hole. The rig must be anchored
properly so that it will not shift. If stakes have been
removed or knocked over, they should be replaced by the
geologist. Also, drillers must ensure the hole is drilled at
the designated angle. The geologist should check the
plunge angle with Brunton compass, and/or the drillers
should use an appropriate measuring device.
Daily Drill Reports Preparation.—The drillers should
prepare duplicate daily drill reports using carbon paper
(additional copies of each report may be required on
contract rigs). All copies must be legible and preferably
printed. One copy should be provided to the geologist for
monitoring progress and for preparation of the geologic
log. The drill report has a space opposite each run for
each item of information required; each of these spaces
need to be filled out completely. Data should be added to
the report or recorded in a notebook after each run.
Drillers should record data as it occurs. See
drawing 40-D-6484 (figure 10-6) as an example for
reporting daily drill activities. Many field offices have
local forms on which these data can be recorded.
Comments regarding specific items to be recorded on the
daily reports are contained in the following paragraphs.
1. Recording depths and core loss — Check for
agreement on depths for intervals drilled by
FIELD MANUAL
296
consecutive shifts. Depths should be recorded in feet
and tenths of feet or to the nearest centimeter, as
appropriate. Tape checks or rod checks may be
required at change of shift or more frequently when
requested by the geologist. The section entitled
“Core Recovery and Core Losses” contains
instructions for proper use of core measurements,
filler blocks (spacers), and tape checks. The driller is
responsible for knowing the depth of the barrel and
the hole at all times. Discrepancies between
intervals drilled and recovery need to be resolved.
Only standard length drill rods should be used. Core
should be measured while it is still in the inner
barrel and after it is placed in the core box.
Record the most correct measurement of the two in
the report. In the event core is left in the hole, the
next run should be shortened accordingly; the left
amount and proper hole entry and startup
procedures should be followed to facilitate recovery.
2. Recording drilling conditions — Make sure
drilling conditions, such as fast or slow, hard or soft,
rough or smooth, even or erratic, moderately fast or
very slow, bit blocks off, etc., are indicated for each
run. Record time in minutes per foot (meter) of
penetration. Any changes in the drilling rate within
a run also should be noted along with intervals of
caving or raveling. If the bit becomes plugged or
blocking off is suspected, the driller should stop
drilling and pull the core barrel. Also, when drill
circulation is lost, the driller should pull and ex-
amine the core.
3. Drilling fluid return and color — The type,
color, and estimated percent of drilling fluids
returned should be recorded for each core run. The
depth of changes in fluid loss or color is particularly
CORE LOGGING
297
important. If drilling mud is used, indicate number
of sacks used per shift. In case of total loss of drilling
fluid, it may be necessary to pressure test the
interval.
4. Description of core — Drillers need to describe
the core in general terms; i.e., moderately hard, very
hard, soft, clay seams, broken, color, etc. If familiar
with the rock types, drillers may report more than
just general terminology.
5. Water-pressure testing — Holes in rock are typi-
cally water tested in 10-foot (3-m) intervals at
pressures of approximately ½ lb/in2 (3.5 kilopascals
[kPa]) to 1 lb/in2 (6.90 kPa) per foot (1/3 m) of cover
up to 100 lb/in2 (690 kPa). NOTE: Pressures may be
modified for each site. Factors such as density of
materials, "overburden pressure" or "cover," bedding,
purpose of testing, distances from free faces, water
levels, and artesian pressures all must be taken into
account so that pressure testing does not
unintentionally hydrofracture the foundation or jack
foundation materials. Pressures should be
determined by the geologist. If a range of pressures
is used, and disproportionately high water losses are
obtained at the higher pressures, the pressures
should be stepped down and water losses at the
lower pressures recorded. Water test pressures
should be stepped up 3 to 5 times and then stepped
down. Flow versus pressure should be plotted; and
if the relationship is not linear or smoothly curved,
hydrofracturing or jacking may be occurring. If the
decreasing pressure curve does not follow the
increasing pressure curve, washing, plugging, or
hydrofracturing or jacking may be occurring without
the foundation materials returning to the prewater
test state. Intentionally increasing the pressure
until the foundation is fractured or jacked is a good
FIELD MANUAL
298
way to determine appro-priate grout pressures.
Gravity tests, overlapping pressure tests, and
variations in the length of the interval tested may be
used to ensure complete test data. For example, a
packer interval of 8 feet (2.4 m) may be used if the
hole is caving too badly to get 10 feet (3 m) of open
hole. Also, if a packer will not seat at 10 feet (3 m)
above the bottom of the hole and there is good rock at
12 feet (3.66 m), a 12-foot test interval may be used.
If losses are above 15 gal/min (1.146 liters per
second [L/sec]), exceed pump or system capacity, or
water is known to be bypassing the packer, reduce
the length of the packer interval and retest.
Losses should be recorded in gallons and tenths of
gal/min (L/sec). The driller should record the water
meter reading at 1-minute intervals, and the test
should be run for a full 5 minutes at each pressure
increment after the flow has stabilized. The driller
should report the average flow in gal/min (L/sec) for
the 5-minute test. Each driller should keep his own
record of the packer data in case questions arise
concerning the testing. A suggested form for
recording data is shown in figure 10-7.
6. Casing or cementing depths — The depth of the
casing or the cemented interval should be shown for
each core run. Do not cement any more of the hole
than is necessary to repair a caving or raveling
interval. The use of additives such as calcium
chloride or aluminum powder, if permitted, will
reduce the set time. These materials should be
added to the water and not to the cement.
7. Recording unusual conditions — All unusual
conditions or events should be noted in the "Notes"
CO
R
E

L
O
G
G
I
N
G
29
9 Figure 10-7.—Water testing record.
FIELD MANUAL
300
column of the report. This includes such items as
sudden changes in drilling speed, loss of circulation,
drop of drill string (open joints or cavities), casing
and cementing procedures, caving, squeezing, packer
failures, and gas.
8. Recording setups, drilling, and downtime —
Time must be noted on reverse side of report. Type,
number, and size of bit is indicated here also.
9. Recording water level measurements —
Measurement should be recorded at the start of each
day shift and shown on the day shift report. Holes
should be jetted or bailed prior to completion of the
hole to obtain reliable water level data. Immediately
after jetting or bailing, the depth to water should be
recorded.
10. Care of core and core boxes — Split-tube
(triple tube) core barrels should be used. If not used,
the core should not be damaged when extracted from
the core barrel. Do not beat on the barrel with a
metal hammer; use a rubber mallet/hammer or a
piece of wood. The best way to remove core from a
solid barrel is by using a pump to pressurize the
inside of the barrel and extrude the core (stand
back!). The mud pump will work satisfactorily for
this. Core should be extracted from the inner tube
and carefully placed into core boxes by hand. The
use of cardboard or plastic halfrounds is
recommended (see figure 10-8. Core pieces should
be fitted into the core box and fragments should
be arranged to save space. Long pieces may
be broken for better fit in the core box, but
a line should be drawn across the core to
denote mechanical breaks. If 5-foot (1.5-m) core
CORE LOGGING
301
Figure 10-8.—Use of half-round to protect core.
FIELD MANUAL
302
boxes are used, mechanical breaks to fit 5-foot runs
in boxes are reduced. Figure 10-9 shows a typical
core box for N-size core.
Core should be placed in the core box from left to
right, with the top to the left, bottom to the right,
starting at the top of the box so the core reads like a
book. The ends and top of the box should be marked
with black enamel paint or indelible felt pen. Core
blocks, which mark the depths, are placed between
each run and the depth marked. Data on the outside
of the left end of the box should include the project,
feature, drill hole number, box number, and depth
interval in the box.
Filler blocks (spacers) are necessary to properly
record information and minimize disturbance to the
core during handling. Blocks should be placed with
a planed side marked with either black enamel paint
or indelible felt-tip pen; 2- by 2-inch (50- by 50-mm)
blocks work well for N-size core. All core runs must
be separated with blocks properly labeled at the top
and bottom of the run. Sample intervals should be
marked in the boxes using wooden blocks of lengths
equal to the missing core so that the sample may be
returned to the box. Gaps for core losses should not
be left in the core box. Core left in the hole and
recovered on the next run may be added to the
previous run. Filler blocks inserted where
unaccountable core losses occur should show the
length of loss in tenths of feet, as follows: LC (lost
core) 0.3 foot, or NR (no recovery) 0.3 foot. The core
loss block indicates that a certain length of core was
unaccountably lost within a run, and the block
should be placed at the depth of the core loss. If
the point of core loss cannot be determined, the block
can be placed in the core box at the bottom of
CO
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E

L
O
G
G
I
N
G
30
3
Figure 10-9.—Standard N-size core
FIELD MANUAL
304
CORE LOGGING
305
the run, preceding the bottom of run block. Cavities
may be marked on the block. All spacer, sample,
and core loss blocks should be nailed to the bottomor sides of the box to prevent movement of the core.
At the drill site, core boxes should be lined up,
preferably on boards or planks, in order from top tobottom, with labels and up side to left, in a safe area
and kept covered with lids. While in the field, donot place boxes where sliding or caving of slopes is
likely to occur and keep out of the way of vehicles
and equipment. Core boxes, especially thosecontaining soft, slaking, or intensely fractured core
material, should be covered immediately to preventdamage by rain or drying. Tray partitions in boxes
should be nailed so that nails do not protrude frombottom of boxes.
When the core is moved, be careful to preventdisturbance, breakage, or spilling. Damage to the
core during transportation can be minimized byusing nailed-down spacers and a 3/4- to 1-inch thick
(19-25-mm) foam-rubber pad placed between the topof the core and the secured core box lid.
Hole Completion.—Completion of the drill hole shouldmeet the requirements established by the exploration
program and at the direction of the field geologist. Drill
holes usually will be completed either with sufficientcasing or plastic pipe to assure that the hole will stay
open for later water level observations. In areas wherevandalism may occur or when long-term monitoring is
contemplated, a standpipe and suitable cap with lockshould be installed. Completion information should be
indicated on the driller's report. The drill hole number
should be stamped or welded into the casing. Ifgroundwater observation riser pipes have been installed,
FIELD MANUAL
306
install a minimum 3-foot (1-m) length of surface casing
with a locking cap as a standpipe to mark the drill hole
and protect the riser pipe. Grouted in place, thisstandpipe can also serve to protect the observation well
from infiltration by surface runoff.
Concrete Core Logging
Concrete structures are commonly cored to assess the
quality of concrete or as part of foundation investigations
on existing features. An early macroscopic assessmentof concrete core is warranted for the following reasons:
•Concrete physical condition may suggest changes
in the drilling program or sampling techniquesthat would be difficult to modify after drilling is
complete. A different approach in drilling orsampling techniques may be necessary to
determine the cause of distress or failure.
•Shipping, handling, and sample preparation may
modify the concrete core by inducing, modifying,or masking fractures or causing core
disintegration.
•Core could be lost or destroyed before reachingthe laboratory.
•Macroscopic examination may provide therequired information eliminating the need for a
petrographic examination.
This section is based on American Society for TestingMaterials Designations (ASTM) C 823-83 and C 856-83.
Purposes of Examination.—Investigations of in-
service concrete conditions are usually doneto: (a) determine the ability of the concrete to perform
CORE LOGGING
307
satisfactorily under anticipated conditions for future
service; (b) identify the processes or materials causing
distress or failure; (c) discover conditions in the concretethat caused or contributed to satisfactory performance or
failure; (d) establish methods for repair or replacementwithout recurrence of the problem; (e) determine
conformance to construction specification requirements;(f) evaluate the performance of the components in the
concrete; and (g) develop data for fixing financial andlegal responsibility.
In addition to the usual drill log information, thefollowing should be provided, if available:
•Reason for and objectives of the coring program.
•Location and original orientation of each core.
•Conditions of operation and service exposure.
•Age of the structure.
•Results of field tests, such as velocity and
rebound or Schmidt hammer data.
Figure 10-10 is an example of a drill hole log showing the
types of information that can be shown and a format for
a log showing both rock and concrete core.
Examination.—Concrete core is commonly marked in
the field showing the top and bottom depths at theappropriate ends and at any of the following features.
Below are listed the major items to examine and record:
Fractures — Cracks or fractures in core are best
seen on smooth surfaces and can be accented bywetting and partial drying of the surface. Old crack
surfaces are often different colors than freshfracture
CORE LOGGING
307
Figure 10-10.—Log of concrete and rock core.
CORE LOGGING
309
surfaces. Old fracture surfaces often have reaction
products or alteration of the surfaces. Fractures
often follow structural weaknesses.
Reacted particles — Rims on gravel or sand areoften caused by weathering processes unless other
factors indicate chemical reactions with the cementpaste. Crushed aggregate with rims probably is due
to chemical reaction with the cement paste.
Reaction products — Crushed aggregate with rims
usually indicates alteration in the concrete, such asalkali-silica reaction or alkali-carbonate reaction.
Rims in paste bordering coarse aggregate and lightcolored areas in the paste may be gel-soaked or
highly carbonated paste adjoining carbonateaggregate that has undergone an alkali-carbonate
reaction. White areas of fairly hard, dry material or
soft, wet material that has fractured and penetratedthe concrete and aggregate or fills air voids should
be recorded. Alkali aggregate reaction products canbe differentiated from calcium carbonate deposits by
using hydrocloric acid. The reaction products do notfizz.
Changes in size or type of fine and coarse
aggregate — Sizes, shapes, and types of aggregate
can vary in a structure due to changes in mixes,placement procedure, or sources and should be
logged.
Voids — Voids (honeycomb, popcorn) are indicatorsof trapped air, inadequate vibration, or insufficient
mortar to effectively fill the spaces among coarseaggregate particles. Voids should be described and
the volume percent estimated.
FIELD MANUAL
310
Segregation of components — Concrete compo-
nents can become segregated or concentrated during
placement. Large aggregate sizes can separate fromfine aggregate, and paste can separate from the
aggregate, especially near forms or finishedsurfaces.
Cold joints or lift lines — Weak joints or zones
can form in concrete due to long periods betweenbuckets or mixer loads. Poor vibration or poor or
improper preparation of previous lift surfaces can
form zones of weakness or actual planes similar tojoints in rock. These surfaces, called lift lines,
should be described and any material on thesurfaces described. Lift lines can be very subtle and
difficult to locate. Design or construction data oftenprovide clues as to where to look for lift lines and
construction joints. The core should be examined
wet. Clues to lift line locations are: (1) alignedaggregate along the surfaces each side of a line,
(2) coarser aggregate above the lift line than is belowthe line, (3) different shape, gradation, or
composition of aggregate above and below the liftline, (4) a thin line of paste on the lift line, and
(5) no aggregate crosses the lift line.
Steel or other imbedded items — Reinforcing steel
and orientations should be described as well as othermaterials encountered such as timber, steel lagging,
dirt, or cooling pipes.
Changes in color of the cement — Changes inpaste color can indicate reaction products or changes
in cement type or cement sources and should belogged.
Aggregate-paste bond — The bond between theaggregate and cement should be described. A good
bond is characterized by concrete breaking through
CORE LOGGING
311
the aggregate and not around the particles. A fair
bond is characterized by concrete breaking through
and around the aggregate. A poor bond has concretebreaking around the aggregate.
Aggregate rock type — The aggregate rock type
can be important in determining the causes ofconcrete problems. For example, limestone often
has chert inclusions suggesting an aggregatereaction, whereas an igneous rock such as granite
probably will not react with cement. Both the coarse
and fine aggregate should be examined.
Aggregate shape — Aggregate shape is usuallyunique to each source. Rounded or subrounded
aggregate is probably natural. Angular (sharp)aggregate is probably crushed.
Mechanical breaks — Mechanical breaks in thecore and whether the break is around or through the
aggregate should be noted.

APPENDIX B
Field Forms
Project Name:
Project #:
Notes:
Coordinate System –
LOG OF BORING
(Page of )
Date Started :
Date Completed :
Drilling Method :
Sampling Method :
Drilling Company :
Driller :
Depth to Water :
Logged By :
Northing :
Easting :
Depth
in
Feet
0
5
10
15
20
25
30
35
40
Sa
m
p
l
e

I
n
t
e
r
v
a
l
Pe
n
.
/
R
e
c
.
Ni
t
r
o
g
e
n

(
p
p
m
)
Ch
l
o
r
i
d
e

(
p
p
m
)
DESCRIPTION
US
C
S
Site Location:__________________Drilling Co:__________________ Depth to Water (ft):_________
Drilling Method:________________Driller:______________________ Total Depth (ft):____________
Drilling Equipment:______________Northing:_____________ Easting:___________________ Borehole Diameter:_________
Sample Method:________________Logger:_____________________ Split Spoon Length: ___________ Coord. System_________________________________
Depth in
Feet (BLS)USCS Descriptor Soil Type Color
Partical
Size Grading Angularity/
shape Density Plasticity Moisture Odor
PID/
FID
%
Rec.
Sample
No./Int.Comments
Sandy SAND very fine poor angular (sand or gravel) non-plastic dry none
very loose
Clayey CLAY fine well subangular loose slightly plastic moist organic
dense
Silty SILT medium subrounded very dense plastic wet hydrocarbon
Gravelly GRAVEL coarse rounded (silt or clay) very plasitc
very soft
soft
hard
very hard
Depth in
Feet (BLS)USCS Descriptor Soil Type Color
Partical
Size Grading Angularity/
shape Density Plasticity Moisture Odor
%
Rec.
Sample
No./Int.Comments
Sandy SAND very fine poor angular (sand or gravel) non-plastic dry none
very loose
Clayey CLAY fine well subangular loose slightly plastic moist organic
dense
Silty SILT medium subrounded very dense plastic wet hydrocarbon
Gravelly GRAVEL coarse rounded (silt or clay) very plasitc
very soft
soft
hard
very hard
Depth in
Feet (BLS)USCS Descriptor Soil Type Color
Partical
Size Grading Angularity/
shape Density Plasticity Moisture Odor
%
Rec.
Sample
No./Int.Comments
Sandy SAND very fine poor angular (sand or gravel) non-plastic dry none
very loose
Clayey CLAY fine well subangular loose slightly plastic moist organic
dense
Silty SILT medium subrounded very dense plastic wet hydrocarbon
Gravelly GRAVEL coarse rounded (silt or clay) very plasitc
very soft
soft
hard
very hard
Depth in
Feet (BLS)USCS Descriptor Soil Type Color
Partical
Size Grading Angularity/
shape Density Plasticity Moisture Odor
%
Rec.
Sample
No./Int.Comments
Sandy SAND very fine poor angular (sand or gravel) non-plastic dry none
very loose
Clayey CLAY fine well subangular loose slightly plastic moist organic
dense
Silty SILT medium subrounded very dense plastic wet hydrocarbon
Gravelly GRAVEL coarse rounded (silt or clay) very plasitc
very soft
soft
hard
very hard
Date: _________ Drilling Start:_________________
Date: _________ Drilling Finish:________________
Boring No.:__________________Soil Boring Log
(Field)

APPENDIX C
ASTM E1689-95(2003)e1 Standard Guide for Developing Conceptual Site Models
for Contaminated Sites

Designation: E1689 – 95 (Reapproved 2008)
Standard Guide for
Developing Conceptual Site Models for Contaminated Sites
1
This standard is issued under the fixed designation E1689; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide is intended to assist in the development of
conceptual site models to be used for the following: (1)
integration of technical information from various sources, (2)
support the selection of sample locations for establishing
background concentrations of substances, (3) identify data
needs and guide data collection activities, and (4) evaluate the
risk to human health and the environment posed by a contami-
nated site. This guide generally describes the major compo-
nents of conceptual site models, provides an outline for
developing models, and presents an example of the parts of a
model. This guide does not provide a detailed description of a
site-specific conceptual site model because conditions at con-
taminated sites can vary greatly from one site to another.
1.2 The values stated in either inch-pound or SI units are to
be regarded as the standard. The values given in parentheses
are for information only.
1.3 This guide is intended to apply to any contaminated site.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
2
D2216 Test Methods for Laboratory Determination of Wa-
ter (Moisture) Content of Soil and Rock by Mass
2.2 EPA Documents:
3
Guidance for Data Useability in Risk Assessment (Part A)
Final, Publication 9285.7-09A,PB 92-963356, April
1992
Guidance for Data Useability in Risk Assessment (Part B),
OSWER Directive 9285.7-09B,May 1992
Guidance for Conducting Remedial Investigations and Fea-
sibility Studies Under CERCLA, OSWER Directive
9355.3-01,October 1988
3. Terminology
3.1 Definitions:
3.1.1 background concentration,n—the concentration of a
substance in ground water, surface water, air, sediment, or soil
at a source(s) or nearby reference location, and not attributable
to the source(s) under consideration. Background samples may
be contaminated, either by naturally occurring or manmade
sources, but not by the source(s) in question.
3.1.2 conceptual site model,n—for the purpose of this
guide, a written or pictorial representation of an environmental
system and the biological, physical, and chemical processes
that determine the transport of contaminants from sources
through environmental media to environmental receptors
within the system.
3.1.3 contaminant,n—any substance, including any radio-
logical material, that is potentially hazardous to human health
or the environment and is present in the environment at
concentrations above its background concentration.
3.1.4 contaminant release,n—movement of a substance
from a source into an environmental medium, for example, a
leak, spill, volatilization, runoff, fugitive dust emission, or
leaching.
3.1.5 environmental receptor,n—humans and other living
organisms potentially exposed to and adversely affected by
contaminants because they are present at the source(s) or along
contaminant migration pathways.
3.1.6 environmental transport,n—movement of a chemical
or physical agent in the environment after it has been released
from a source to an environmental medium, for example,
movement through the air, surface water, ground water, soil,
sediment, or food chain.
3.1.7 exposure route,n—the process by which a contami-
nant or physical agent in the environment comes into direct
contact with the body, tissues, or exchange boundaries of an
1 This guide is under the jurisdiction of ASTM Committee E47 on Biological
Effects and Environmental Fate and is the direct responsibility of Subcommittee
E47.05 on Risk Assessment, Communication and Management.
Current edition approved Feb. 1, 2008. Published February 2008. Originally
approved in 1995. Last previous edition approved in 2003 as E1689–95(2003)
´1.
DOI: 10.1520/E1689-95R08.
2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 Available from Standardization Documents Order Desk, Bldg 4 Section D, 700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
1
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

Copyright by ASTM Int'l (all rights reserved); Mon May 16 16:58:28 EDT 2011
Downloaded/printed by
Angela Persico (INTERA,+Inc.) pursuant to License Agreement. No further reproductions authorized.
environmental receptor organism, for example, ingestion, in-
halation, dermal absorption, root uptake, and gill uptake.
3.1.8 migration pathway,n—the course through which
contaminants in the environment may move away from the
source(s) to potential environmental receptors.
3.1.9 source,n—the location from which a contaminant(s)
has entered or may enter a physical system. A primary source,
such as a location at which drums have leaked onto surface
soils, may produce a secondary source, such as contaminated
soils; sources may hence be primary or secondary.
4. Summary of Guide
4.1 The six basic activities associated with developing a
conceptual site model (not necessarily listed in the order in
which they should be addressed) are as follows: (1) identifi-
cation of potential contaminants; (2) identification and charac-
terization of the source(s) of contaminants; (3) delineation of
potential migration pathways through environmental media,
such as ground water, surface water, soils, sediment, biota, and
air; (4) establishment of background areas of contaminants for
each contaminated medium; (5) identification and character-
ization of potential environmental receptors (human and eco-
logical); and (6) determination of the limits of the study area or
system boundaries.
4.2 The complexity of a conceptual site model should be
consistent with the complexity of the site and available data.
The development of a conceptual site model will usually be
iterative. Model development should start as early in the site
investigation process as possible. The model should be refined
and revised throughout the site investigation process to incor-
porate additional site data. The final model should contain
sufficient information to support the development of current
and future exposure scenarios.
4.3 The concerns of ecological risk assessment are different
from those of human-health risk assessment, for example,
important migration pathways, exposure routes, and environ-
mental receptors. These differences are usually sufficient to
warrant separate descriptions and representations of the con-
ceptual site model in the human health and ecological risk
assessment reports. There will be elements of the conceptual
site model that are common to both representations, however,
and the risk assessors should develop these together to ensure
consistency.
5. Significance and Use
5.1 The information gained through the site investigation is
used to characterize the physical, biological, and chemical
systems existing at a site. The processes that determine
contaminant releases, contaminant migration, and environmen-
tal receptor exposure to contaminants are described and inte-
grated in a conceptual site model.
5.2 Development of this model is critical for determining
potential exposure routes (for example, ingestion and inhala-
tion) and for suggesting possible effects of the contaminants on
human health and the environment. Uncertainties associated
with the conceptual site model need to be identified clearly so
that efforts can be taken to reduce these uncertainties to
acceptable levels. Early versions of the model, which are
usually based on limited or incomplete information, will
identify and emphasize the uncertainties that should be ad-
dressed.
5.3 The conceptual site model is used to integrate all site
information and to determine whether information including
data are missing (data gaps) and whether additional informa-
tion needs to be collected at the site. The model is used
furthermore to facilitate the selection of remedial alternatives
and to evaluate the effectiveness of remedial actions in reduc-
ing the exposure of environmental receptors to contaminants.
5.4 This guide is not meant to replace regulatory require-
ments for conducting environmental site characterizations at
contaminated (including radiologically contaminated) sites. It
should supplement existing guidance and promote a uniform
approach to developing conceptual site models.
5.5 This guide is meant to be used by all those involved in
developing conceptual site models. This should ideally include
representatives from all phases of the investigative and reme-
dial process, for example, preliminary assessment, remedial
investigation, baseline human health and ecological risk as-
sessments, and feasibility study. The conceptual site model
should be used to enable experts from all disciplines to
communicate effectively with one another, resolve issues
concerning the site, and facilitate the decision-making process.
5.6 The steps in the procedure for developing conceptual
site models include elements sometimes referred to collectively
as site characterization. Although not within the scope of this
guide, the conceptual site model can be used during site
remediation.
6. Procedure
6.1 Assembling Information—Assemble historical and cur-
rent site-related information from maps, aerial images, cross
sections, environmental data, records, reports, studies, and
other information sources. A visit(s) to the site by those
preparing the conceptual site model is recommended highly.
The quality of the information being assembled should be
evaluated, preferably including quantitative methods, and the
decision to use the information should be based on the data’s
meeting objective qualitative and quantitative criteria. For
more information on assessing the quality and accuracy of
data, see Guidance for Data Useability in Risk Assessment
(Part A)and Guidance for Data Useability in Risk Assessment
(Part B).Methods used for obtaining analytical data should be
described, and sources of information should be referenced. A
conceptual site model should be developed for every site unless
there are multiple sites in proximity to one another such that it
is not possible to determine the individual source or sources of
contamination. Sites may be aggregated in that case. A
conceptual model should then be developed for the aggregate.
6.2 Identifying Contaminants—Identify contaminants in the
ground water, surface water, soils, sediments, biota, and air. If
no contaminants are found, the conceptual site model should be
used to help document this finding.
6.3 Establishing Background Concentrations of
Contaminants—Background samples serve three major func-
tions: (1) to establish the range of concentrations of an analyte
attributable to natural occurrence at the site; (2) to establish the
range of concentrations of an analyte attributable to source(s)
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other than the source(s) under consideration; and (3) to help
establish the extent to which contamination exceeds back-
ground levels.
6.3.1 The conceptual site model should include the naturally
occurring concentrations of all contaminants found at the site.
The number and location of samples needed to establish
background concentrations in each medium will vary with
specific site conditions and requirements. The model should
include sufficient background samples to distinguish contami-
nation attributable to the source(s) under consideration from
naturally occurring or nearby anthropogenic contamination.
The procedures mentioned in 6.2 and 6.3 are sometimes
grouped under the general heading of contaminant assessment
and may be performed as a separate activity prior to the
development of a conceptual site model.
6.4 Characterizing Sources—At a minimum, the following
source characteristics should be measured or estimated for a
site:
6.4.1 Source location(s), boundaries, and volume(s).
Sources should be located accurately on site maps. Maps
should include a scale and direction indicator (for example,
north arrow). They should furthermore show where the
source(s) is located in relationship to the property boundaries.
6.4.2 The potentially hazardous constituents and their con-
centrations in media at the source.
6.4.3 The time of initiation, duration, and rate of contami-
nant release from the source.
6.5 Identifying Migration Pathways—Potential migration
pathways through ground water, surface water, air, soils,
sediments, and biota should be identified for each source.
Complete exposure pathways should be identified and distin-
guished from incomplete pathways. An exposure pathway is
incomplete if any of the following elements are missing: (1)a
mechanism of contaminant release from primary or secondary
sources, (2) a transport medium if potential environmental
receptors are not located at the source, and (3) a point of
potential contact of environmental receptors with the contami-
nated medium. The potential for both current and future
releases and migration of the contaminants along the complete
pathways to the environmental receptors should be determined.
A diagram (similar to that in Fig. X1.4) of exposure pathways
for all source types at a site should be constructed. This
information should be consistent with the narrative portion and
tables in the exposure assessment section of an exposure or risk
assessment. Tracking contaminant migration from sources to
environmental receptors is one of the most important uses of
the conceptual site model.
6.5.1 Ground Water Pathway—This pathway should be
considered when hazardous solids or liquids have or may have
come into contact with the surface or subsurface soil or rock.
The following should be considered further in that case:
vertical distance to the saturated zone; subsurface flow rates;
presence and proximity of downgradient seeps, springs, or
caves; fractures or other preferred flow paths; artesian condi-
tions; presence of wells, especially those for irrigation or
drinking water; and, in general, the underlying geology and
hydrology of the site. Other fate and transport phenomena that
should be considered include hydrodynamic dispersion, inter-
phase transfers of contaminants, and retardation. Movement
through the vadose zone should be considered.
6.5.2 Surface Water and Sediment Pathway—This pathway
should always be investigated in the following situations: (1)a
perennial body of water (river, lake, continuous stream, drain-
age ditch, etc.) is in direct contact with, or is potentially
contaminated by a source or contaminated area, (2) an unin-
terrupted pathway exists from a source or contaminated area to
the surface water, (3) sampling and analysis of the surface
water body or sediments indicate contaminant concentrations
substantially above background, (4) contaminated ground wa-
ter or surface water runoff is known or suspected to discharge
to a surface water body, and (5) under arid conditions in which
ephemeral drainage may convey contaminants to downstream
points of exposure.
6.5.3 Air Pathway—Contaminant transport through the air
pathway should be evaluated for contaminants in the surface
soil, subsurface soil, surface water, or other media capable of
releasing gasses or particulate matter to the air. The migration
of contaminants from air to other environmental compartments
should be considered, for example, deposition of particulates
resulting from incineration onto surface waters and soil.
6.5.4 Soil Contact Pathway—Contaminated soils that may
come into direct contact with human or ecological receptors
should be investigated. This includes direct contact with
chemicals through dermal absorption and direct exposure to
gamma radiation from radioactively contaminated soil. There
is a potential for human and ecological receptors to be exposed
to contaminants at different soil depths (for example, humans
may be exposed to only surface and subsurface soils, whereas
plants and animals may encounter contaminants that are buried
more deeply). This should be considered when contaminated
soils are being evaluated.
6.5.5 Biotic Pathway—Bioconcentration and bioaccumula-
tion in organisms and the resulting potential for transfer and
biomagnification along food chains and environmental trans-
port by animal movements should be considered. For example,
many organic, lipophilic contaminants found in soils or sedi-
ments can bioaccumulate and bioconcentrate in organisms such
as plankton, worms, or herbivores and biomagnify in organ-
isms such as carnivorous fish and mammals or birds. The
movement of contaminated biota can transport contaminants.
6.6 Identifying Environmental Receptors—Identify environ-
mental receptors currently or potentially exposed to site
contaminants. This includes humans and other organisms that
are in direct contact with the source of contamination, poten-
tially present along the migration pathways, or located in the
vicinity of the site. It is advisable to compile a list of taxa
representative of the major groups of species present at the site.
It will rarely be possible or desirable to identify all species
present at a site. It is recommended that the conceptual site
model include species or guilds representative of major trophic
levels. The complexity and iterative nature of the conceptual
site model has already been mentioned in 4.2.
6.6.1 Human Receptors—The conceptual site model should
include a map or maps indicating the physical boundaries of
areas within which environmental receptors are potentially or
currently exposed to the source(s) or migration pathways;
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separate maps may be prepared to illustrate specific contami-
nants or groups of contaminants. In addition, the human
receptors should be represented in a figure similar to Fig. X1.4,
which is based on Guidance for Conducting Remedial Inves-
tigations and Feasibility Studies Under CERCLA.Fig. X1.4
shows the potentially exposed populations, sources, and expo-
sure routes. It represents a clear and concise method of
displaying exposure information.
6.6.2 Ecological Receptors—The conceptual site model
should include a map or maps identifying and locating terres-
trial and aquatic habitats for plants and animals within and
around the study area or associated with the source(s) or
migration pathways. Consult local and state officials, U.S.
Environmental Protection Agency regional specialists, and
Natural Resource Trustees to determine whether any of the
areas identified are critical habitats for federal- or state-listed
threatened or endangered species or sensitive environments.
Identify all dominant, important, declining, threatened, endan-
gered, or rare species that either inhabit (permanently, season-
ally, or temporarily) or migrate through the study area.
7. Keywords
7.1 conceptual site model; ecological; hazardous waste site;
human health; risk assessment; site characterization
APPENDIX
(Nonmandatory Information)
X1. OUTLINE FOR A CONCEPTUAL SITE MODEL FOR CONTAMINATED SITES
X1.1 The conceptual site model should include a narrative
and set of maps, figures, and tables to support the narrative.An
outline of the narrative sections, along with an example for
each section, is given below. The example is based on an
hypothetical landfill site at which only preliminary sampling
data are available.The landfill site example is intentionally
simplified and is for illustrative purposes only. Conceptual site
models may contain considerably more detail than provided in
this example.
X1.1.1 Brief Site Summary—Summarize the information
available for the site as this information relates to the site
contaminants, source(s) of the contaminants, migration path-
ways, and potential environmental receptors. A brief descrip-
tion of the current conditions at the site (photographs optional)
should be included. The inclusion of a standard 7.5-min United
States Geological Survey topographic quadrangle map or
geologic quadrangle map, or both, that shows the location of
the site is recommended. All maps should contain directional
information (for example, north arrow) and a scale.
Example—Geophysical surveys, aerial photographs, and
subsurface exploration at Landfill No. 1 (LF-1) reveal the
presence of at least one northeast-southwest trending waste
trench. The trench is 300-ft (91-m) long and 100-ft (30-m)
wide. Maximum depth of the trench indicated by the soil
borings is 22 ft (7 m). As determined from the soil boring
program, the waste material samples indicated that metal
concentrations were at or below background concentrations,
with the exception of cadmium and manganese in one sample.
However, solvents (methylene chloride and trichloroethene
(TCE) and pesticides (DDE, DDT, and DDD) were found at
concentrations above background in soil boring samples. Soil
samples taken from beneath the fill indicate that downward
migration of contaminants has occurred. The surficial aquifer
(ABC Formation) contains naturally high dissolved solids
(>2000 mg/L) with yields of less than 4 gpm. Ground water
flow in the surficial aquifer is toward the southeast at a rate of
approximately 15 ft (5 m) per year. The terrain is flat with
seeded and natural grasses and small (15-ft (5-m)), widely
spaced loblolly pine tress covering the site. The site is fenced
and unused currently.
X1.1.2 Historical Information Concerning the Site:
X1.1.2.1 Site Description—Describe the history of the site,
paying particular attention to information affecting the present
environmental condition of the site.
Example—LF-1, operated from 1960 to 1968. This trench-
type landfill was reportedly used for the disposal of construc-
tion rubble and debris, packing material, paper, paints, thin-
ners, unrinsed pesticide containers, oils, solvents, and
contaminated fuels. Most of the trenches for waste disposal
were reportedly oriented east-west and were 75-ft (23-m) wide,
350-ft (107-m) long, and an estimated 20-ft (6-m) deep. A few
empty containers presumably buried in the landfill have
worked their way to the surface and are partially exposed at the
site. The site was partly covered by an unpaved industrial
haulage road. The site was fenced in 1985 and has been unused
since.
X1.1.2.2 Source Characterization—Present site-specific in-
formation to identify and define the location, size, and condi-
tion of the source(s) of contamination at the site.
Example—Four soil borings were used to characterize the
waste disposal units at LF-1.Fig. X1.1 illustrates the soil
boring locations. The depth of the soil borings were SB05 = 28
(9 m), SB06 = 30 ft (9 m), SB07 = 30 ft (9 m) and SB08 = 30
ft (9 m) below ground surface. Two of the borings, SB07 and
SB08, encountered refuse/waste material. In SB08, the refuse
was encountered from approximately 8 to 22 ft (2 to 7 m)
below ground surface. The material was noted to be burnt
debris, glass, and organic matter. A much dryer and thinner
waste zone was encountered at SB07. The base of the excava-
tion at this location was approximately 10 ft (3 m). Material
that appeared to be burnt trash was noted in the backfill. The
remaining two borings, SB05 and SB06, did not encounter
waste. One sample was collected from each of these borings
(SB05 and -06). These samples were used as background
samples. Additional samples were collected from SB07 and
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SB08, within the landfill, to characterize the source. Analytical
results are summarized in Table X1.1.
Petroleum hydrocarbons, which were suspected of being
contaminants based on the site history, were not detected in any
of the samples.
Volatile organic compounds found in the samples included
methylene chloride and TCE. Methylene chloride was found in
all soil samples in trace amounts (0.005 to 0.008 mg/kg).
The field quality control information suggests that methyl-
ene chloride may be a field artifact. The chlorinated solvent,
TCE, was found significantly above background only at SB08
at a concentration of 0.05 mg/kg.
Organochlorine pesticides (DDE, DDD, and DDT), which
were suspected of being present based on the site history, were
not present above the detection limit in any of the samples.
Comparing metal concentrations of soil samples from SB05
and SB06 (background samples) with the remaining soil
samples (SB07 and SB08) reveals that SB08 metals data
exceeded the background soils data substantially for one
analyte. That analyte was manganese (4320 mg/kg).
X1.1.2.3 Migration Pathway Descriptions—Describe the
route(s) potentially taken by contaminants from the site as they
migrate away from the source through the environmental
media (ground water, surface water, air, sediment, soils, and
food chain).
Example:Ground Water Migration—Three monitor wells
(MWs) were installed at LF-1. The bedrock formation is
typically nonwater-bearing and consists of thick clay and
clay-stone (Fig. X1.2). The unconsolidated materials above the
bedrock include a layer of fluvial terrace deposits. The sand
FIG. X1.1 Location Map for Landfill Number 1; Contours Showing the Potentiometric Surface from which Ground Water Flow Direction
was Determined Could be Included in a Separate Figure to Avoid Clutter
TABLE X1.1 Summary of Analytical Results at LF-1
A
Parameter (Method)
Field Identification Number
DLB Units SB05
C SB06 SB07 SB08
Moisture (Test Method D2216)N/AD% 20.6 19.1 12.7 21.1
Petroleum hydrocarbons (SW3550/E418.1) 25 mg/kg ND25E ND25 ND25 ND25
Volatile organics (SW8240)
Methylene chloride
F 0.005 mg/kg 0.008 ND0.0050 ND0.0050 ND0.0050
Trichloroethene 0.005 mg/kg 0.006 ND0.0050 ND0.0050 0.05
Organochlorine pesticides (SW3550/8080) mg/kg
4,4-DDE 0.0033 mg/kg ND0.0033 ND0.0033 ND0.0033 ND0.0033
4,4-DDD 0.0033 mg/kg ND0.0033 ND0.0033 ND0.0033 ND0.0033
4,4-DDT 0.0033 mg/kg ND0.0033 ND0.0033 ND0.0033 ND0.0033
Metals (SW3050/6010)
Cadmium 0.5 ND0.5 ND0.5 ND0.5 ND0.5 ND0.5
Manganese 2 mg/kg 284 178 228 4320
A All results are expressed on a dry weight basis.
B DL = detection limit.
C SB = soil boring.
D N/A = not applicable.
E NDx = not detected at concentration x.
F Suspected laboratory contaminant.
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and gravels that lie above the bedrock contain water with flow
velocities of approximately 13 to 18 ft/year (4 to 5 m/year).
Flow velocities were estimated from permeability tests con-
ducted at MW06. Recharge at the site is from runoff associated
with the nearby area that pools and stagnates at and near the
site.Table X1.2 contains the water quality analyses from
samples of MW05, MW06 (upgradient), and MW07 (down-
gradient). The upgradient samples contained no contaminants
at concentrations above the detection limits, while the down-
gradient sample contained organic contaminants (pesticides).A
comparison of metals from the downgradient and upgradient
samples indicates that the concentration of metals in the
downgradient ground water does not exceed background (up-
gradient) concentrations.
Example:Surface Water and Sediment Migration—The site
surface water drainage map is shown in Fig. X1.3. Three
FIG. X1.2 Cross Section of Landfill Number 1
TABLE X1.2 Ground and Surface Water Quality Analysis at LF-1
Parameter Field Identification Number
DLA MW-05 µg/L MW-06µ g/L MW-07 µg/L
Volatile organics
Trichloroethene 5 ND5B ND5 ND5
Methylene chloride 5 ND5 ND5 ND5
Organochlorine pesticides
4,4-DDE 0.1 ND0.1 ND0.1 1
4,4-DDD 0.1 ND0.1 ND0.1 3
4,4-DDT 0.1 ND0.1 ND0.1 4
Metals
Cadmium 5 ND5 ND5 ND5
Manganese 15 ND15 ND15 ND15
DL Water µg/L SW-02 µg/L SW-03 µg/L SW-04 mg/kg SD-02 mg/kg SD-03 mg/kg SD-04
Petroleum hydrocarbons 1000 ND1000 ND1000 ND1000 ND1000 ND1000 ND1000
Volatile organics
Trichloroethene 1 ND1 ND1 ND1 ND1 ND1 ND1
Methylene chloride 2 ND2 ND2 ND2 ND2 ND2 ND2
Organochlorine pesticides
4,4-DDE 0.04 ND0.04 ND0.04 ND0.04 ND0.04 ND0.04 ND0.04
4,4-DDD 0.1 ND0.1 ND0.1 ND0.1 ND0.1 ND0.1 ND0.1
4,4-DDT 0.1 ND0.1 ND0.1 ND0.1 ND0.1 ND0.1 ND0.1
Metals
Cadmium 5 ND5 ND5 ND5 ND0.5 ND0.5 ND0.5
Manganese 20 ND20 ND20 ND20 ND2 ND2 ND2
A DL = detection limit.
B NDx = not detected at concentration x.
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surface water runoff samples and three sediment samples were
collected at locations shown on the map. Samples SW-02 and
SD-02 were collected to determine background, while SW-03,
SW-04, SD-03, and SD-04 were placed downstream of the site.
The analytical results given in Table X1.2 indicate that no
contaminants are present above background in any of the
samples. There appears to be no contamination entering the
surface water pathway from the site.
Example:Air Migration—No air samples were taken since
there was no indication that vapor or dust can enter the air
pathway. The contamination is buried and effectively prevented
from reaching the air pathway, and the site is covered by a
thick layer of vegetation, which effectively acts as a natural cap
and prevents dust from becoming airborne. Qualitative air
monitoring showed no evidence of any organic vapors being
present at the site during the initial stages of the site investi-
gation.
Example:Soils—This pathway is not complete for humans
because the site is surrounded by a 6-ft (2-m) fence with a
padlocked gate and posted with no trespassing signs. Soil and
sediment samples taken for the surface water pathway did not
indicate the presence of contamination above background
concentrations. Also, there was no loose soil at the site since
the site was covered by a thick layer of vegetation. Exposed,
empty containers have been tested for the presence of contami-
nant residues, and none have been found. The site was
inspected for evidence of burrowing mammals and other small
mammals, reptiles, amphibians, or birds that might not be
deterred by the fence. There was no evidence of any threat to
ecological receptors from the soils or direct contact.
Example:Food Chain Transfer—Samples collected from
surface water, sediment, and soils indicate that there are no
contaminants present at concentrations above background.
There is therefore no concern for food chain transfer (biomag-
nification) in and around the landfill.
X1.1.2.4 Environmental Receptor Identification and
Discussion—Current and future human and ecological receptor
groups should be identified and located on site maps. The
migration pathways and source(s) that place or potentially
place the environmental receptors at risk should be discussed.
Example:The only residential housing in the vicinity of the
site is approximately 2100 ft northwest of the landfill. The
surficial aquifer is not used as a source of drinking water by the
residents, and the ground water flow is toward the southeast
and away from the residential housing. There is an active golf
course just to the west of the residential housing. Golf Course
Lake is recharged from north of the lake and is not influenced
by LF-1. The golf course does not use the surficial aquifer for
a drinking water source or for irrigating the golf course. There
are no other human receptors in the vicinity of the site. There
are no local, state, or federally designated declining, endan-
gered, or rare species that inhabit or migrate through the
vicinity of the study area. Other wildlife species that were
observed on-site show no evidence of harm from the site.
Plants on-site include seeded, cool-season grasses, and volun-
teer native grasses; herbian vegetation; upland shrubs; and
coniferous trees. None of the vegetation shows signs of stress.
The most likely potentially threatened aquatic habitats are
Small Lake and Big River, south of the landfill. However,
environmental sampling of surface water and sediments (Table
X1.2) has not shown any evidence of contaminant migration
from the landfill to the lake or river.Fig. X1.4 illustrates the
relationships among the elements of the conceptual site model,
FIG. X1.3 Surface Drainage Pattern around Landfill Number 1
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including the sources, release mechanisms, pathways, and
environmental receptors.
X1.2 Examples of Maps, Tables, and Figures:
X1.2.1 Maps—The use of maps in a conceptual site model
is important. The maps may include United States Geological
Survey topographic and geologic maps, site sketch maps, and
maps drawn to scale. The maps should identify and locate key
elements of the conceptual site model including source(s);
ground water, surface water, sediment, soil and air pathway
routes (direction of flow); and areas covered by environmental
receptor populations and migration pathways. Morphological
and geological features relevant to the environmental assess-
ment of the site should be included on a map.
Example:Figs. X1.1-X1.3 are examples of sketch maps that
contain a scale, a north arrow, and a legend.
X1.2.2 Tables and Figures—Tables and figures should be
simple and easy to read, with explanations of qualified data and
abbreviations.All tables and figures should be referred to in the
narrative.
Examples:Tables X1.1 and X1.2 and Figs. X1.1-X1.3 are
examples of simple summary tables and site maps.Fig. X1.4 is
an example of a diagram illustrating the relationships between
primary and secondary sources, release mechanisms, exposure
routes, and environmental receptors.
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of infringement of such rights, are entirely their own responsibility.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and
if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards
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NOTE 1—This example is based on Figure 2-2 of Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA.
FIG. X1.4 Example Diagram for a Conceptual Model at Landfill Number 1
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APPENDIX D
Standard Operating Procedures for Isotope Analysis

Standard Operating Procedures

Ammonia Nitrogen Isotope Analysis
Yi Wang, PhD
Director, ZymaX Forensic Isotopes, Escondido, CA 92029-1917
Phone: [phone] ext 43, Email: [e-mail]

Standard operating procedures on how to collect water/soil samples and how to perform isotope
analysis have been prepared at ZymaX Forensic Isotope Laboratory:

Sample Collection
Soil samples are collected in the field into 4-8 oz. glass jars. Water samples are collected in the field into
500-1000mL poly bottles. Sample containers are provided free of charge upon our clients’ request.
Keep samples refrigerated until shipping them on ice overnight to the lab. Once samples arrive at the
lab, they will be logged in and kept refrigerated at ~4°C until isotope analysis, which should be done
within 14 days.

Sample Preparation
1. Make sufficient volume of solution of 2M H2SO4-each sample needs 25uL.
2. Combust GF/D filters (1 per sample); MgO (3g/L sample); GF/F filters (1 per sample); NaCl (50g/L
for freshwater samples only) in high temperature oven at 400°C for 4 hours.
3. Add 250mL of water sample into Mason jars and also add required NaCl for each sample. Add stir
bar and stir Mason jar on stir pad for about 5min to help dissolve some of the NaCl.
4. Create “ammonia trap filter pack” and let it sit on watch glass in Mason jar in the following steps:
Fold 2 paper towels into 5x7 in squares; Cover the paper towels in tin foil; Clean tin foil with
ethanol or methanol; Place 2.5cm Teflon disk down on tin foil; Place a combusted GF/D disk on
top of the Teflon disk in the center; Pipette 25uL of 2M H2SO4 solution onto the GF/D disk; Place
another Teflon disk on top of the GF/D like creating a sandwich; Use a 10mL VOA vial with cap
removed to press shut the sandwich and to create a seal around the GF/D filter disk. The pressure
along with the “cushion’ from the paper towels will be enough to seal the Teflon.
5. Place sandwich filter paper onto watch glass and make sure when the lid is screwed on the watch
glass is high enough so that the water does not splash onto the filter. While filter is on watch
glass, remove lid and add MgO (0.75g/0.25L) to sample water. Close lid immediately after adding
MgO as vapor given off is NH4.
6. Place Mason jars on stir plate once more to incorporate all the MgO into the sample water then
place Mason jars in shaker.
7. Leave jars in there for 2 weeks at 40°C. After that, remove lid and remove filter paper sandwich
and place on clean watch glass in dessicator with a small beaker containing 10mL of sulfuric acid
(to keep the dessicator free of trace ammonia).
8. On the day of nitrogen isotope analysis, cut the GF/D filter into small sections and analyzed in the
Elemental Analyzer.

Isotope Analyses
GF/D filter sample is introduced into an elemental analyzer by EuroVector (EuroEA3028-HT). The EA is
used to convert ammonia sulfate on the filter into nitrogen gas, and the EA is connected to a continuous
flow isotope ratio mass spectrometer (Micromass Isoprime), which determines the differences in the
isotope-amount ratios of stable nitrogen isotopes (15N/14N) of the product N2 gas. The pyrolysis is
quantitative, no isotopic fractionation is involved. Samples are placed in tin capsules and loaded into the
EuroCAP solid auto-sampler. Under computer control, samples are introduced into a heated tube
(1030°C) called reaction tube then a reduction tube (650°C). All reaction takes place in a He atmosphere
(90mL/min). Reaction products are transported by a He carrier. The gas-phase products, mainly N2 are
purified by a gas chromatograph.
The gas is then introduced into the mass spectrometer through an interface, which is also used to inject
N2 reference gas and He for sample dilution. The mass spectrometer is capable of measuring
mass/charges (m/z) 28, 29 and 30 simultaneously. The ion beams from N2 are as follows: m/z 28 =14N14N;
m/z 29=15N14N primarily. ISOPRIME software is capable of processing data automatically.
Stable isotope ratios are conventionally referenced to an internationally recognized standard, and are
expressed in the notation, for nitrogen,
15N = (Rsample/Rstandard -1) × 1000, and R = 15N/14N
Units are per mil (‰). The standard, by definition, has a value of 0‰, and samples may have positive
or negative values depending on whether the sample is enriched or depleted in the heavier isotope.
The international standard for nitrogen is the atmosphere air (Air).
All water samples are analyzed in batches of a maximum of 40 per day. Three internationally distributed
isotopic reference materials with different values are analyzed at the beginning of a batch and also
among the samples, which shall have the same acceptance criteria as acceptance criteria for the
unknown samples (=<0.3‰).
Isotope Data Reporting and Turnaround Time
Analytical precision and laboratory quality controls (QCs) are reported with sample results. Promised
standard turnaround time at ZymaX Forensic Isotopes is 60 days, further, rush services (30 days) is
possible upon request, with additional charges.