DRC-2011-006616 - 0901a06880245bcb

DENISO
MINES
yii"
Denison Mines (USA) Corp.
105017th Street, Suite 950
Denver, CO 60265
USA
Tel: [phone]
Fax:[phone]
www.denisonmines.com
June 3, 2011
VIA PDF and FEDERAL EXPRESS
Mr, Rusty Lundberg
ExecutiveSecretary
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 paragraph 4 of the Tolling Agreement, Rev. 1, dated April 28, 2011 between
Denison Mines (USA) Corp. ("Denison") and the Co-Executive
Quality Board, please fmd enclosed Denison's Draft Nitrate Investigation Revised Phases 2 to 5
Work Plan/White Mesa Mill Site, Blanding Utah:
Our proposed schedule for the nitrate investigation assumes that the Division ofRadiation
Control will provide any comments on this draft document by June 24,2011. We respectftilly
request that DRC provide comments to Denison by that date.
Please contact me at 303-389-4132 if you have any questions on this submittal.
Yours very truly,
Jo Ann S. Tischler
Director, Compliance and Permitting
Enclosure.
cc Robert D. Baird, URS
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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
June 3, 2011

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TABLE OF CONTENTS
LIST OF FIGURES ..................................................................................................................... iv 
LIST OF TABLES ....................................................................................................................... iv 
LIST OF APPENDICES ............................................................................................................. iv 
ABBREVIATIONS AND ACRONYMS ..................................................................................... v 
1.0 INTRODUCTION............................................................................................................. 1 
1.1 Problem Definition.................................................................................................. 4 
1.1.1 Purpose of the Investigation........................................................................ 4 
1.1.1.1 Phase 2 – Groundwater Quality Sampling and Analysis ............. 5 
1.1.1.2 Phase 3 – Deep Bedrock Core Sampling and Analysis ............... 5 
1.1.1.3 Phase 4 – Stable Isotopic Sampling and Analysis ....................... 5 
1.1.1.4 Phase 5 – Isotopic Soil Sampling and Analysis ........................... 6 
1.1.2 Site Description and Background ............................................................... 6 
1.1.2.1 Site Status..................................................................................... 7 
1.1.2.2 Physical Setting ............................................................................ 7 
1.1.3 Summary of Previous Investigations .......................................................... 8 
1.2 Project Description ................................................................................................ 10 
1.2.1 Project Objectives ..................................................................................... 10 
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 .................................................................................... 12 
1.3.4 Completeness ............................................................................................ 12 
1.3.5 Comparability ........................................................................................... 12 
1.3.6 Detection and Quantitation Limits ............................................................ 12 
1.4 Project Organization ............................................................................................. 13 
1.4.1 Functional Groups ..................................................................................... 13 
1.4.2 Overall Responsibility for the QA/QC Program ....................................... 13 
1.4.3 Data Requestors/Users .............................................................................. 13 
1.4.4 Data Generators ........................................................................................ 13 
1.4.4.1 Sampling and QC Monitors ....................................................... 13 
1.4.4.2 Analysis Monitor ....................................................................... 14 
1.4.4.3 Data Reviewers/Approvers ........................................................ 14 
1.5 Special Training and Certification ........................................................................ 15 
1.6 Documents and Records ....................................................................................... 15 
1.6.1 Field Documentation ................................................................................. 15 

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1.6.2 Reports Generated ..................................................................................... 15 
2.0 CONCEPTUAL SITE MODEL .................................................................................... 17 
2.1 Site Summary ........................................................................................................ 17 
2.2 Site Description ..................................................................................................... 17 
2.2.1 ID Contaminants ....................................................................................... 17 
2.2.2 Establishing Background Concentrations of Contaminants ..................... 17 
2.2.3 Source Locations, Boundaries, and Volumes ........................................... 18 
2.2.4 Time of Initiation, Duration, and Rate of Contaminant Release .............. 19 
2.3 Migration Pathway Descriptions........................................................................... 20 
2.3.1 Soil and bedrock ....................................................................................... 22 
2.3.2 Groundwater ............................................................................................. 22 
2.3.3 Specific Source Locations and Data Needs .............................................. 22 
2.3.3.1 Potential Nitrate/Chloride Source Locations: ............................ 24 
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 
3.3 Phase 3 Deep Bedrock Core Sampling and Analysis ........................................... 85 
3.3.1 Sampling Design ....................................................................................... 85 
3.3.2 Field Activities and Sampling Methods .................................................... 87 
3.3.2.1 Sample Identification ................................................................. 87 
3.3.3 Sample Containers and Holding Times .................................................... 88 
3.3.4 Analytical Methods ................................................................................... 88 
3.4 Phase 4 Stable Isotopic Sampling and Analysis of Groundwater in
Existing Wells ....................................................................................................... 88 
3.5 Phase 5 Isotopic Soil Sampling and Analysis ....................................................... 88 
3.6 Sample Handling and Custody .............................................................................. 89 
3.6.1 Sample Labeling ....................................................................................... 89 
3.6.2 Sample Documentation ............................................................................. 89 
3.6.3 Chain of Custody ...................................................................................... 90 
3.6.4 Sample Shipment ...................................................................................... 91 
3.7 Quality Control ..................................................................................................... 92 
3.7.1 Field Quality Control Methods ................................................................. 92 
3.7.2 Analytical Laboratory Quality Control Methods ...................................... 92 

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3.7.2.1 Spikes, Blanks and Check Samples ........................................... 92 
3.7.3 Internal Quality Control Checks ............................................................... 93 
3.7.3.1 Field Quality Control Check Procedures ................................... 93 
3.7.3.2 Review of Compliance with Procedures in this Plan ................. 93 
3.7.3.3 Completeness Review ................................................................ 93 
3.7.3.4 Duplicates .................................................................................. 93 
3.7.3.5 Use of QC Samples to Assess Conformance with this Plan ...... 94 
3.7.4 Instrument Equipment Testing, Inspection, and Maintenance .................. 94 
3.7.5 Instrument Calibration .............................................................................. 94 
4.0 DATA EVALUATION ................................................................................................... 95 
5.0 AUDITS ........................................................................................................................... 96 
5.1 System Audits ....................................................................................................... 96 
5.2 Performance Audits .............................................................................................. 96 
5.3 Follow-Up Actions................................................................................................ 96 
5.4 Audit Records ....................................................................................................... 96 
6.0 REFERENCES ................................................................................................................ 97 

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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 Map Showing Location of Cross Sections
Figure 7 Interpretive Northeast-Southwest Cross Section (NE-SW)
Figure 8 Interpretive Northeast-Southwest Cross Section (NE2-SW2)
Figure 9 Interpretive Northwest-Southeast Cross Section (NW-SE)
Figure 10 Elevation of Bedrock Surface Showing Thickness of Mancos Shale and Cross
Sections SW-NE, NW-SE, and SW2-NE2
Figure 11 Potential Natural Nitrate Reservoir Source
Figure 12 Potential Process-Related Source Where Mancos is Thin
Figure 13 Potential Process-Related Source Where Mancos is Thick
Figure 14 Potential Pond or Pond-Like Source
Figure 15 Logic Diagram for Potential Natural Nitrate Reservoir Source Investigation
Figure 16 Logic Diagram for Potential Process Related Source Investigation
Figure 17 Logic Diagram for Potential Pond and Pond-Like Source Investigation
Figure 18 Logic Diagram for Groundwater Investigation
Figure 19 Diagram for Conceptual Site Model (CSM)
Figure 20 Phase 3 Coring 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 3 Coring Sample Locations
Table 4 Phase 3 Coring Laboratory Analytical Parameters

LIST OF APPENDICES
Appendix A ASTM E1689 Standard Guidance for Development of a Conceptual Site
Model
Appendix B Field Forms

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ABBREVIATIONS AND ACRONYMS
Agreement States State agencies authorized to implement the U.S. Nuclear Regulatory
Commission’s licensing program under the Atomic Energy Act
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
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

GWDP Groundwater Discharge Permit
GPS global positioning system

ID identification
INTERA INTERA Incorporated

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

MDL method detection limit
mg/L milligrams per liter
Mill White Mesa Mill
msl mean sea level

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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
NRC U.S. Nuclear Regulatory Commission

PG Professional Geologist

QA Quality Assurance
QA/QC Quality Assurance/Quality Control
QAP Quality Assurance Plan

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
SHP southern high plains
Site White Mesa Mill
SPLP Synthetic Precipitate Leaching Procedure

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

UDEQ Utah Department of Environmental Quality

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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 ammonia, 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 an amendment to the deadline stipulated in
item 7.C of the Consent Agreement. DUSA requested item 7.C 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.

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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,
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.

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The Tolling Agreement was revised on April 28, 2011, to allow time for:
 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.
This document is the revised Work Plan for Phases 2 through 5, which is being submitted in
accordance with the Revised Tolling Agreement and which contains information for the
execution of Phases 2 through 5 as described in the Revised Tolling Agreement. The Phase 2
through 5 Work Plan requirements specified in the Revised Tolling Agreement Section 4 are
shown below.
4. Revised Phase 2 through 5 – on or before June 3, 2011, DUSA shall complete and
submit for Co-Executive secretary review and approval a Revised Phase 2 through 5 Work
Plan and Schedule, 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.
As discussed during the April 20, 2011 meeting, and as described on page 4 of the
Revised Tolling Agreement, detailed Quality Assurance Plans (“QAPs”) for the
groundwater quality sampling, and for the stable isotope sampling of groundwater
and soil will be submitted separately prior to those field efforts, if those field
efforts are required.
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.

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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).
Logic diagrams are attached as figures to this 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, both Mill-related sources, non-Mill 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. This Work Plan describes the remaining
phases of the investigation per the Revised Tolling Agreement. Each of the phases contemplated
by the Revised Tolling Agreement are 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,

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equipment, procedures, objectives, and decision criteria for each of the phases specified in the
Revised Tolling Agreement.
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 QAP Addendum for conventional
groundwater sampling and analysis will be submitted which specifies the specific details,
activities, equipment, procedures, objectives, and decision criteria for this phase of the
investigation. The QAP Addendum will be based upon the existing DRC-approved QAP for
groundwater sampling at the White Mesa Mill. The Addendum will follow the same outline as
the approved QAP and will supplement the approved QAP to address those activities which are
specific to Phase 2 of the Nitrate Investigation. The QAP Addendum will be submitted to DRC
on or before July 22, 2011. The schedule assumes DRC will complete review by August 5, 2011
and DUSA will submit a Final QAP by August 12, 2011. Sampling will occur in either Q3 or
Q4 2011.
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. The schedule assumes DRC will
complete review of this plan by June 24, 2011 and DUSA will submit a Final plan by July 15,
2011. Sampling will be completed in August 2011.
1.1.1.3 Phase 4 – Stable Isotopic Sampling and Analysis
Stable isotopes of nitrogen, sulfate, and ammonia 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 QAP Addendum for isotopic groundwater sampling and
analysis will be submitted which specifies the specific details, activities, equipment, procedures,
objectives, and decision criteria for this phase of the investigation. The QAP Addendum will be
based upon and utilize the existing DRC-approved QAP for groundwater sampling at the White
Mesa Mill. The Addendum 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. The QAP Addendum will be submitted to DRC on or before September 16,

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2011. The schedule assumes DRC will complete review by October 7, 2011 and DUSA will
submit a Final QAP by October 28, 2011. Sampling will be completed by January 31, 2012.
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 soil or deep
cores. If this phase is required, a separate Work Plan/QAP will be submitted which specifies 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 after
consultation with DRC determines this phase is needed.
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 Historic Pond.
 Agricultural activities.
 The former Fly Ash Pond.
 Potential historic spills of ammonia-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.

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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 Ashland 1 and Linde formally
utilized sites 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 that are 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 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’s rise to more than 11,000 feet above mean
sea level (“msl”), and have likely provided a source of sediments to the Mill site (5,600 feet
above msl) 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

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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
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,

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2009), an Initial Nitrate Monitoring Report (DUSA, 2009), and quarterly nitrate and chloride
reporting to the DRC (DUSA, 2010-2011), and ongoing investigations into historic 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 Historic Pond, the former Fly Ash Pond, potential historic spills of ammonia-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 source for nitrate
and chloride comes 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
Historic Pond, and possible influences from septic leach fields at the Site, in particular, the Semi
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 historic land uses has
continued to be updated through literature, Internet, and other land use studies, 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, historical Landsat satellite imagery, and an Internet-based search
of historic 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

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contamination to be unsubstantiated with direct and reliable evidence. Furthermore, the
NOTICE stated that DUSA has additionally identified several onsite 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:
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. All rock core descriptions will be described using

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the guidelines presented in the State of New York Department of Transportation Rock Core
Evaluation Manual (NYDOT, 2006). 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 for 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, sulfate, and ammonia using EPA Method
353.2, EPA Method 300.0, and EPA Method 350.1 respectively.
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 for 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 concentration for field duplicate samples
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

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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
condition. Representativeness is controlled by performing all sampling in compliance with this
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.

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1.4 Project Organization
1.4.1 Functional Groups
This 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.
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 Plan is necessary for management to
make informed decisions in order 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 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. Sample collection, record keeping, and QA/QC activities are
conducted by one or more sampling and QC/data monitors (each a “Sampling and QC Monitor”).
The Sampling and QC Monitors perform all field sampling activities, collect all field QC
samples, and perform all data recording and chain of custody (“COC”) activities in accordance
with this 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 specific the 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:

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a. Ensuring that samples are collected, preserved, and transported as specified in the 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 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’
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 Plan.

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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 Plan, to minimize
contamination.
d. Supervising all QA/QC measures to assure proper adherence to this Plan and determining
corrective measures to be taken when deviations from this Plan occur.
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 Standard Practice for Description and
Identification of Soils (visual-manual procedure) and the NYDOT Rock Core Evaluation
Manual.
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
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 E 1698 Standard Guidance for Development of a Conceptual Site
Model (Appendix A).
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 the
chloroform plume with 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 Historic Pond.
 Agricultural activities.
 The former Fly Ash Pond.
 Potential historic spills of ammonia-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). “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
                                                            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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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 Historic 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.
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.

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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 cubic meters/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. Using the highest of the
estimated range of pore velocities, 49.5 ft/yr, it would have taken a minimum of 57 years for
nitrate to travel from TWN-2 to MW-31 in groundwater. If the Historic 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
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.

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Thirty one (31) 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 consists of 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. Figures 11 through 14 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.
Figure 10 shows a paleoridge of Mancos Shale in the vicinity of the Mill site that would likely
impact seepage from potential sources in two ways: 1) the thicker the Mancos, the slower the
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
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 Historic Pond is less than 5 feet and is not
expected to be a significant barrier.

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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 an 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 discontinuous shale and conglomeratic
zones present in the Dakota Sandstone and Burro Canyon Formations.
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 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 15-18) and the CSM diagram (Figure 19), potential source locations can be classified by
type: potential mill-process-related sources, potential pond-related sources (Fly Ash Pond,
Historic 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.

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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
Denison 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 16, 2011.
2) Isotopic Analysis
Phase 4 of the investigation contemplates the performance of a stable isotopes 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 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 each of
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
potential source based on the existing weight of evidence (the “Weight of Evidence”). For the
purposes of this 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.

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4) Potential and Possible Sources
In the discussion in Section 2.3.3.1 below, all sources to be evaluated under this 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 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 Scalehouse, 1985 to present)
2. Sewage vault/lift station (currently active)
3. Scale house leach field, (also known as Leach Field south of Scalehouse, 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)
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)

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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 Scalehouse, 1985 to present)
Hypothesis 1: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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 (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).
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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct

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coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples 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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2. Sewage vault/lift station (currently active)
Hypothesis 2: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples and of

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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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3. Scale house leach field, (also known as Leach Field south of Scalehouse, 1977-1979)
Hypothesis 3: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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 (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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples and of

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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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4. Former office leach field
Hypothesis 4: Nitrates and chlorides associated with sewage and or laboratory wastes (prior
to 1981) may have leached through alluvial soil and bedrock to groundwater and
contributed to the 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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

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in the plume, conduct Isotopic Analysis on samples of bedrock core samples 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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5. Ammonia tanks
Hypothesis 5: Ammonium may have leaked from the tanks through the alluvial soil and
bedrock to groundwater to the plume and was 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. 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 ammonia) form continuously through the alluvium and the bedrock. The
ammonia 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 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
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).

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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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If nitrate is not present above
background in the alluvium and bedrock down to groundwater, this can be eliminated as a
potential source. If nitrate is present above background, conduct mass balance calculation
to determine if the concentrations in alluvium and bedrock are sufficient to have
contributed to nitrate observed in the plume. If the concentrations in bedrock are sufficient
to have contributed to nitrate observed in groundwater, conduct an Isotopic Analysis on
samples of bedrock core samples and of groundwater from the plume (Phase 5). If the
Isotopic Fingerprint is uniquely identifiable to the potential source, then the source of
nitrate 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 of nitrate has been identified. If a
possible source of nitrate has been identified, perform a Weight of Evidence analysis to
determine if the possible source has contributed nitrate to the plume. If the possible source
has been determined to have contributed nitrate to the plume, perform a hydrogeologic and
mass balance analysis to determine to what extent the source has contributed nitrate to the
plume.

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6. SAG leach field (Leach Field north of mill building, 1998 to 2009)
Hypothesis 6: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples and of

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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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7. Cell 1 leach field (Leach Field east of Cell #1, 1979 to 1985)
Hypothesis 7: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples and of

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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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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 flyash,
containing oxidized nitrogen (the nitrate not ammonium form) sporadically from 1980 to
1989. The pond could potentially have received some washwaters containing ammonium
nitrogen from the vanadium circuit from 1980 through the present.
Necessary Conditions: a) Is there evidence of nitrate, and/or ammonium, and chloride
concentrations in the vadose zone beneath this feature? c) If ammonium is present, is there
an oxidation source adjacent to or beneath the tanks sufficient to convert ammonium 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 and/or chloride observed in the plume? and d) 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). If only ammonium nitrogen is present
above background, identify whether there is a sufficient oxidation source to convert

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ammonia to nitrate. Analyze bedrock core samples for nitrate, chloride, and ammonium
concentration data. If none of those constituents are present above background, then this
can be eliminated as a potential source. If any of those constituents are present above
background, conduct mass balance calculation to determine if the concentrations in
bedrock are sufficient to have contributed to nitrate and chloride observed in groundwater.
If the concentrations in bedrock are sufficient to have contributed to nitrate and chloride
observed in groundwater, conduct isotopic analysis on samples of bedrock core samples
and of groundwater from the plume (Phase 5). If the isotopic fingerprint of the core sample
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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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 a not a
source of nitrogen atoms and has been retained for evaluation 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? Since this source is not associated with any nitrate, is there a
plausible alternate source for nitrate? 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 chloride 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 chloride 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
chloride concentration data. If chloride is present above background, conduct a mass
balance calculation to determine if the concentrations in bedrock are sufficient to have
contributed to chloride observed in the plume. If chloride is not present above background
or the quantities are not sufficient, this can be eliminated as a potential source. If the
concentrations in bedrock are sufficient to have contributed to chloride observed in the

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plume, conduct Isotopic Analysis on samples of bedrock core samples and of groundwater
from the plume (Phase 5). If the Isotopic Fingerprint is uniquely identifiable to the
potential source, then the chloride 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 chloride to the plume. If the
possible source has been determined to have contributed chloride to the plume, perform a
hydrogeologic and mass balance analysis to determine to what extent the source has
contributed chloride to the plume.

Nitrate Investigation Revised Phases 2-5 Work Plan
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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 ammonia 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.
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 ammonia 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, sulfate, and ammonium concentration data. If nitrate is not present above
background in alluvium and bedrock down to groundwater, this can be eliminated as a
potential source. If nitrate is present above background, conduct mass balance calculation
to determine if the concentrations in alluvium and bedrock are sufficient to have
contributed to nitrate observed in the plume. If the concentrations in bedrock are sufficient
to have contributed to nitrate observed in plume, conduct Isotopic Analysis on samples of
bedrock core samples and of groundwater from the plume (Phase 5). If the Isotopic
fingerprint is uniquely identifiable to the potential source, then the source of nitrate 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 of nitrate has been identified. If a possible
source of nitrate has been identified, perform a Weight of Evidence analysis to determine if
the possible source has contributed nitrate to the plume. If the possible source has been
determined to have contributed nitrate to the plume, perform a hydrogeologic and mass
balance analysis to determine to what extent the source has contributed nitrate to the plume.

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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.
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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct a
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of those constituents are

Nitrate Investigation Revised Phases 2-5 Work Plan
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present above background then this can be eliminated as a potential source. If any of those
constituents are present above background, 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 samples 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. Further, if
cryptosporidium is present along with elevated nitrate in water or alluvium, 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
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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.
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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct a
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of those constituents are
observed above background, then this is eliminated as a potential source. If any of those

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constituents are present above background, 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 samples 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. Further, if
cryptosporidium is present along with elevated nitrate in water or alluvium, 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
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13. Former vault/lift station (to Former Office Leach Field) (1992 to 2009)
Hypothesis 13: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples and of

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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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14. Truck shop leach field (1979-1985)
Hypothesis 14: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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 Isotopic Analysis on samples of bedrock core samples and of

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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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15. New Counter Current Decant/Solvent Extraction (CCD/SX) leach field (currently
active)
Hypothesis 15: Nitrates and chlorides associated with sewage may have leached through
alluvial soil and bedrock to groundwater and contributed to the plume. Note: 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of these constituents are
present above background in alluvium and bedrock down to groundwater, this can be
eliminated as a potential source. If any of those constituents are present above background,
conduct 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

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concentrations in bedrock are sufficient to have contributed to nitrate and chloride observed
in the plume, conduct Isotopic Analysis on samples of bedrock core samples 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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16. Historic Pond
Hypothesis 16-1: The historic pond was associated with agriculture and may have been
used as a stock pond, a fertilizer mixing pond, or collected fertilizer from runoff of nearby
agricultural land. Nitrate and chloride laden water from the historic 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 historic pond. Historical sheep dipping activities may also have impacted the
pond.
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
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

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groundwater. 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. 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
the results of Phase 1 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, sodium, or ammonium) are present above background,
conduct coring study of bedrock to groundwater (Phase 3). Analyze bedrock core
samples for nitrate, sodium, chloride, and ammonium concentration data. If none of those
constituents are present above background, this can be eliminated as a potential source. If
any of those constituents are present above background, conduct 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 samples 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. Further, if cryptosporidium is
present along with elevated nitrate in water or alluvium, 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.
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 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.

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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.
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 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 background, 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 background, this can be eliminated as a
potential source. If any of those constituents are present above background, 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

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bedrock are sufficient to have contributed to nitrate and chloride observed in the plume,
conduct an Isotopic Analysis on samples of bedrock core samples 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.
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, and
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: 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. Data on concentrations of chemical constituents in groundwater that might be
associated with agricultural or military uses of this feature (Phase 2). If the results of Phase
1 sampling of the alluvium provide evidence that any of the constituents (nitrate, chloride,
or ammonium) are present above background, conduct coring study of bedrock to
groundwater (Phase 3). Analyze bedrock core samples for nitrate, chloride, and
ammonium concentration data. If none of those constituents are present above backgroung,

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this can be eliminated as a potential source. If any of those constituents are present above
background, 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 samples
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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Hypothesis 17-2: The wildlife pond was historically associated with agriculture and may
have been used as a stock pond, a fertilizer mixing pond, or 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: 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. Data on concentrations of chemical constituents in groundwater that might be
associated with agricultural or military uses of this feature (Phase 2). If the results of Phase
1 sampling of the alluvium provide evidence that any of the constituents (nitrate, chloride,
or ammonium) are present above background, conduct coring study of bedrock to
groundwater (Phase 3). Analyze bedrock core samples for nitrate, chloride, and
ammonium concentration data. If none of those constituents are present above backgroung,
this can be eliminated as a potential source. If any of those constituents are present above

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background, 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 samples
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. Further, if cryptosporidium is present along with
elevated nitrate in water or alluvium, 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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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 lab may have
leached through the alluvial soil and bedrock to groundwater and contributed to the plume.
The minilab areas use very small quantities of reagents and process solutions which drain
either to an above-the floor bucket, or 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.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonia-bearing chemicals or
chloride-bearing chemicals used in this 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? c) If only ammonia-bearing compounds were used, is there an oxidation source
adjacent to or beneath the lab sufficient to convert ammonia 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 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 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,

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and ammonium is 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, ammonia-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 ammonia 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
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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 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.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonia-bearing chemicals or
chloride-bearing chemicals used in this 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 ammonia-bearing compounds were used, is there an oxidation source
adjacent to or beneath the lab sufficient to convert ammonia 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. 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 is 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
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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, ammonia-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 ammonia 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
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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 ammonia 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 ammonia)
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
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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 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 the results of Phase 1
sampling of the alluvium provide evidence that any of the constituents (nitrate, chloride, or
ammonium) are present above background, conduct a coring study of bedrock to
groundwater (Phase 3). Analyze bedrock core samples for nitrate, chloride, and
ammonium concentration data. If nitrate is not present above background in alluvium and
bedrock down to groundwater, this can be eliminated as a source. If nitrate is present
above background, conduct a mass balance calculation to determine if the concentrations in
alluvium and bedrock are sufficient to have contributed to nitrate observed in the plume. If
the concentrations in bedrock are sufficient to have contributed to nitrate observed in the
plume, conduct an Isotopic Analysis on samples of bedrock core samples 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
White Mesa Mill Site, Blanding, Utah 70 June 3, 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 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
minilab areas use very small quantities of reagents and process solutions which drain either
to an above-the floor bucket, or 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.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonia-bearing chemicals or
chloride-bearing chemicals used in this 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 ammonia-bearing compounds were used, is there an oxidation source
adjacent to or beneath the lab sufficient to convert ammonia 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 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 is already available from the groundwater and nitrate monitoring programs.

Nitrate Investigation Revised Phases 2-5 Work Plan
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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, ammonia-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 ammonia 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
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22. Chem Lab
Hypothesis 22: Ammonium-, nitrate- or chloride-bearing chemicals from the mini-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.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonia-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 ammonia-bearing compounds were used, is there an
oxidation source adjacent to or beneath the lab sufficient to convert ammonia 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 is 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
follows. If no nitrate-bearing, ammonia-bearing or chloride-bearing compounds were used

Nitrate Investigation Revised Phases 2-5 Work Plan
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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 ammonia 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
White Mesa Mill Site, Blanding, Utah 74 June 3, 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.
Necessary Conditions: a) Were nitrate-bearing chemicals, ammonia-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 ammonia-bearing compounds were used, is there an
oxidation source adjacent to or beneath the lab sufficient to convert ammonia 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 is 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
follows. If no nitrate-bearing, ammonia-bearing or chloride-bearing compounds were used

Nitrate Investigation Revised Phases 2-5 Work Plan
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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 ammonia 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
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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,
through the alluvial soil and bedrock into groundwater, before entering the tailings system,
and have contributed 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.
Necessary Conditions: a) Is there evidence of a failure of the floor sump and/or floor
drains? 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 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: 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
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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: 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 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 the results of Phase 1
sampling of the alluvium provide evidence that any of the constituents (nitrate, chloride, or
ammonium) are present above background, conduct a coring study of bedrock to
groundwater (Phase 3). Analyze bedrock core samples for nitrate, chloride, and
ammonium concentration data. If nitrate is not present above background in alluvium and
bedrock down to groundwater, this can be eliminated as a potential source. If nitrate is
present above background, conduct a mass balance calculation to determine if the
concentrations in alluvium and bedrock are sufficient to have contributed to nitrate
observed in the plume. If the concentrations in bedrock are sufficient to have contributed to
nitrate observed in the plume, conduct an Isotopic Analysis on samples of bedrock core
samples 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
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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, through the alluvial soil and bedrock into groundwater, before entering
the tailings system, and have contributed 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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct a
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
chloride concentration data. If chloride is present above background, conduct a mass

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balance calculation to determine if the concentrations in bedrock are sufficient to have
contributed to chloride observed in the plume. If chloride is not present above background
or the quantities are not sufficient, this can be eliminated as a potential source. 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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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: 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 sampling of the alluvium provide evidence that any of the
constituents (nitrate, chloride, or ammonium) are present above background, conduct a
coring study of bedrock to groundwater (Phase 3). Analyze bedrock core samples for
nitrate, chloride, and ammonium concentration data. If none of those constituents are
present above background, this may be eliminated as a potential source. If any of those
constituents are present above background, 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 groundwater, conduct an Isotopic Analysis

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on samples of bedrock core samples 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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26. Other ponds or pond like sources (26-32)
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 historic 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: Perform a hydrogeologic evaluation to determine if any potential
contamination from this potential source could have contributed to the plume. If not, this

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potential source is ruled out. If the hydrogeologic analysis is not conclusive, proceed as
follows. Review data on concentrations of chemical constituents in groundwater that might
be associated with agricultural or military uses of this feature (Phase 2). If the results of
Phase 1 sampling of the alluvium provide evidence that any of the constituents (nitrate,
chloride, or ammonium) are present above background, conduct coring study of bedrock to
groundwater (Phase 3). Analyze bedrock core samples for nitrate, chloride, and
ammonium concentration data. If none of those constituents are present above background,
then this may be eliminated as a potential source. If any of those constituents are present
above background, 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 samples
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. Further, if cryptosporidium is present along with
elevated nitrate in water or alluvium, 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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2.4 Environmental Receptor Identification
An environmental receptor can be humans or other living organisms 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.
2.4.2 Ecological
Potential ecological receptors are not at risk from nitrates and chlorides in soil. Potential
ecological receptors do not come into contact with groundwater at the Mill site; therefore, the
ecological risk pathway is incomplete.

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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 exists 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 Phase 1 Work Plan.
3.2 Phase 2 Groundwater Quality Sampling and Analysis
A separate QAP Addendum will be submitted which specifies the specific details, activities,
equipment, procedures, objectives, and decision criteria for this phase of the investigation. The
QAP Addendum will be based upon and utilize the existing DRC-approved QAP for
groundwater sampling at the White Mesa Mill. The Addendum will follow the same outline as
the approved QAP and will: a) supplement 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) adjust existing procedures in the approved QAP which need to be modified or
omitted to be suitable for the Nitrate Investigation.
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:
Phase 3A Deep Bedrock Coring in Undisturbed Locations, and Phase 3B Deep Bedrock Coring
of Potential Nitrate Source Locations.
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. At the time of this
Phases 2-5 work plan, analytical results have not been received; therefore, exact locations of
bedrock cores cannot be listed here. Figure 20 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

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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), where 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 is detected above background 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 ammonia.
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 in alluvial material will be selected
based on analytical results from the source borings conducted in Phase 1B of this investigation.
At the time of this Phase 2-5 work plan, analytical results have not been received; therefore,
exact locations of bedrock cores cannot be listed here. The bedrock core will be advanced
through the alluvium and bedrock to groundwater. Water levels in the perched aquifer have been
relatively stable for the last 20 years. Therefore, the presence of nitrate and chloride above
background in the 10-foot interval above the water table 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 1/3, second 1/3, and third 1/3 interval of the total penetrated depth at each location,
but during 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 ammonia. The remaining core will be
archived. If any nitrate and/or chloride is detected above background 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.

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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 ammonia 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 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.
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
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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 3 and 4.
3.3.4 Analytical Methods
All rock samples will be submitted to the Analytical Laboratory for SPLP 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 ammonia 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
A separate QAP Addendum will be submitted which specifies the specific details, activities,
equipment, procedures, objectives, and decision criteria for this phase of the investigation. The
QAP Addendum will be based upon and utilize the existing DRC-approved QAP for
groundwater sampling at the White Mesa Mill. The Addendum 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.
3.5 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 soil or deep
cores. If Phase 5 is required, a separate Work Plan/QAP will be submitted which specifies the
specific details, activities, equipment, procedures, objectives, and decision criteria for this phase
of the investigation.

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3.6 Sample Handling and Custody
3.6.1 Sample Labeling
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
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
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.
 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.

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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
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.

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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, radioactive, or 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.
 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.

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 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 quality control 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
Table 4, 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
analytical precision. Assessment of the matrix spike/matrix spike duplicate will be
completed using the method- and Analytical Laboratory-established limits.

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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 Plan
Observation of technician performance is monitored by the QA Manager on a periodic basis to
ensure compliance with this 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 analyses 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 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
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4.0 DATA EVALUATION
What data will be collected, and decisions based on data collected, etc.
(Discuss Logic Diagrams here?)
Data evaluation will be completed as described throughout this 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
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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 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.

Nitrate Investigation Revised Phases 2-5 Work Plan
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6.0 REFERENCES
ASTM International. 2005. Standard Guide for Direct Push Soil Sampling for Environmental
Site Characterizations ASTM D 6282-98 (Reapproved 2005).
––––––. 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.
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
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.
INTERA, Inc. 2009. Nitrate Contamination Investigation Report, White Mesa Uranium Mill
Site, Blanding, Utah.
––––––. 2011. Phase I Work Plan
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.
State of New York Department of Transportation (NYDOT), 2006. Rock Core Evaluation
Manual. Geotechnical Engineering Manual GEM-23, Geotechnical Engineering Bureau,
August. 2006.

Nitrate Investigation Revised Phases 2-5 Work Plan
White Mesa Mill Site, Blanding, Utah 98 June 3, 2011
N:\Nitrate Investigation and CIR\Phase 2 to 5 Plan Revised\Ph 2 to 5 Plan 06.01.11\Phases_2-5_Work_Plan_06_03_2011 ‐ KAW.docx
Tischler, Jo Ann, 2009. Preliminary Source Review Report for Nitrate and Chloride in
Groundwater at the White Mesa Mill
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.

Table 1. Work Plan Schedule
Denison White Mesa Mill Nitrate and Chloride Investigation
2013
Phase Task and Subtask Description
12345678910111213141516171819202122
1 GEOPROBE INVESTIGATION
Potential Natural Nitrate Source Borings, field tests
Potential Process Related Source Borings
Laboratory Analysis SPLP
Meeting to share data with DRC
2 GROUNDWATER SAMPLING FOR NON‐ISOTOPIC ANALYTES
Submit Groundwater QAP Addendum
Water Sampling
Laboratory Analysis
Meeting to share data with DRC
3 DEEP BEDROCK CORE SAMPLING AND ANALYSIS
Potential Natural Nitrate Source Coring
Potential Process Related Source Corings
Laboratory Analysis SPLP
Meeting to share data with DRC
HYDROGEOLOGIC EVALUATION
Perfrom Evaluation 
Review Findings with DRC
4 STABLE ISOTOPE STUDY, LABORATORY ANALYSIS
Submit Groundwater QAP Addendum
Water sampling from existing well locations
Laboratory analysis
Meeting to share data with DRC
5 ISOTOPIC SOIL SAMPLING AND ANALYSIS (IF NEEDED)
Submit QAP
Soil Boring at Identified Source
Laboratory Analysis
Meeting to share data with DRC
REPORT OF FINDINGS
Integrate Information From All Phases
Mass Balance Evaluation
Discuss interim findings with DRC
Draft and Internal Review
Final
April May June July Aug Sept Oct Nov Dec Jan Feb Mar April May June July August Sept Oct Nov Dec Jan
Month
2011 2012

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 Locationof Whate 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 September, October, or November of 2009. A single data point was used for each well.
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)
Chloride data from September, October, or November of 2009. A single data point was used for each well.
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
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
5
5
5
5

WESTWATER SEEP
ENTRANCE SPRING
CORAL CANYON SEEP
FROG POND
Lawzy Lake

PIEZ-5
100
100
100
100
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)
Chloride Concentration (mg/L)
Nitrate data from September, October, or November of 2009. A single data point was used for each well.
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
1,200 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. 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)
Nitrate data from September, October, or November of 2009. A single data point was used for each well.
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
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.

)LJXUHV
FRQWLQXHG
APPROVED DATE REFERENCE FIGURE
HYDRO
GEO
CHEM, INC.
Cell No. 1
Mill Site
Cell No. 2
Cell No. 3
Cell No. 4A
5
16
15
14
6
18
17
7
19
8
20
13
12
4
2
3
11
1
10
9
Cell No. 4B
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\Figure21_CoringLocs.mxd
Figure 20
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

Tables

Well Date
Chloride 
(mg/L)Qual Nitrate 
(mg/L Qual
MW‐1 11/18/2010 15 0.1 U
MW‐2 11/17/2010 7 0.05 U
MW‐3 11/19/2010 63 0.4
MW‐3A 11/22/2010 59 1.2
MW‐4 2/23/2011 40 4.6 D
MW‐5 11/11/2010 52 0.2
MW‐11 2/2/2011 32 0.1 U
MW‐12 11/19/2010 63 0.1 U
MW‐14 2/7/2011 20 0.1 U
MW‐15 11/11/2010 41 0.1
MW‐17 11/17/2010 38 0.9
MW‐18 11/18/2010 52 0.1 U
MW‐19 11/18/2010 25 2.4 D
MW‐20 2/16/2011 64 4.1 D
MW‐22 2/8/2011 57 2.5 D
MW‐23 11/22/2010 9 0.2
MW‐24 11/17/2010 48 0.1
MW‐25 2/2/2011 30 0.1 U
MW‐26 2/16/2011 59 0.6
MW‐27 2/9/2011 46 6 D
MW‐28 11/12/2010 107 0.2
MW‐29 11/9/2010 39 0.1 U
MW‐30 2/1/2011 134 16 D
MW‐31 2/1/2011 145 21 D
MW‐32 11/10/2010 35 0.1 U
Piez‐1 1/31/2011 60 7 D
Piez‐2 1/31/2011 9 0.3
Piez‐3 1/31/2011 40 1.8 D
TW4‐1 2/24/2011 41 6.6 D
TW4‐10 2/23/2011 62 9 D
TW4‐11 2/23/2011 46 6.5 D
TW4‐12 2/15/2011 31 6.5 D
TW4‐13 2/15/2011 60 5.5 D
TW4‐14 2/15/2011 25 1.8 D
TW4‐16 2/22/2011 86 7 D
TW4‐17 2/23/2011 40 0.1 U
TW4‐18 2/22/2011 52 10 D
TW4‐19 2/17/2011 135 17 D
TW4‐2 2/24/2011 46 7 D
TW4‐20 2/23/2011 220 4.4 D
TW4‐21 2/22/2011 303 9 D
Table 2: Summary of the Most Recent
Chloride and Nitrate Concentrations in Groundwater
Nitrate Investigation Revised Phase 2‐5 Work Plan
White Mesa Mill Site
May 27, 2011 
Page 1 of 2
Well Date
Chloride 
(mg/L)Qual Nitrate 
(mg/L Qual
Table 2: Summary of the Most Recent
Chloride and Nitrate Concentrations in Groundwater
TW4‐22 2/23/2011 114 18 D
TW4‐23 2/16/2011 44 0.1 U
TW4‐24 2/17/2011 1100 31 D
TW4‐25 2/16/2011 315 15 D
TW4‐26 2/22/2011 30 10 D
TW4‐3 2/15/2011 23 3.5 D
TW4‐4 2/23/2011 41 7 D
TW4‐5 2/22/2011 34 7 D
TW4‐6 2/23/2011 40 0.7
TW4‐7 2/23/2011 45 3.6 D
TW4‐8 2/16/2011 52 0.1 U
TW4‐9 2/17/2011 41 1.3
TWN‐1 1/26/2011 17 0.5
TWN‐10 1/27/2011 40 0.3
TWN‐11 1/27/2011 84 1.4
TWN‐12 1/26/2011 87 4.2 D
TWN‐13 1/25/2011 103 1.6 D
TWN‐14 1/28/2011 24 3.7 D
TWN‐15 1/27/2011 43 1.4
TWN‐16 1/27/2011 34 4.6 D
TWN‐17 2/1/2011 90 8.6 D
TWN‐18 1/27/2011 61 1.4
TWN‐19 2/1/2011 114 7 D
TWN‐2 2/1/2011 93 43 D
TWN‐3 2/1/2011 138 24 D
TWN‐4 1/25/2011 21 0.9
TWN‐5 1/25/2011 47 0.4
TWN‐6 1/26/2011 18 1.1
TWN‐7 1/27/2011 6 1.3
TWN‐8 1/25/2011 13 0.1 U
TWN‐9 2/1/2011 217 9.5 D
UWLP 1/31/2011 1 0.1
Nitrate Investigation Revised Phase 2‐5 Work Plan
White Mesa Mill Site
May 27, 2011 
Page 2 of 2
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-Ʃ-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride 
and Sulfate (EPA 300.0) Ammonia 
(EPA 350.1)
TBD C-††A-Ʃ-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride 
and Sulfate (EPA 300.0) Ammonia 
(EPA 350.1)
TBD C-††A-Ʃ-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride 
and Sulfate (EPA 300.0) Ammonia 
(EPA 350.1)
TBD C-††A-Ʃ-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-Ʃ-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride 
and Sulfate (EPA 300.0) Ammonia 
(EPA 350.1)
TBD C-††B-Ʃ-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride 
and Sulfate (EPA 300.0) Ammonia 
(EPA 350.1)
TBD C-††B-Ʃ-dd Rock 200 g Ziploc Bag
Nitrate+Nitrite (EPA 353.2) Chloride 
and Sulfate (EPA 300.0) Ammonia 
(EPA 350.1)
TBD C-††B-Ʃ-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 locaƟon ID from Phase 1 and Ʃ-dd is the sample depth interval
C-††A-Ʃ-ddD
C-††B-Ʃ-ddD
Table 3: 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 Phase 2-5 Work Plan
White Mesa Mill Site
 May 27, 2011
Page 1 of 1
Nitrate Investigation Revised Phase 2-5 Work Plan May 27, 2011
White Mesa Mill Site Page 1 of 1
Table 4: 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.

Appendix A
ASTM E1689 Standard Guidance for
Development of a Conceptual Site Model

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
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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.
E1689 – 95 (2008)
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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.
E1689 – 95 (2008)
6

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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
E1689 – 95 (2008)
7

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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.
ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
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
and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
make your views known to the ASTM Committee on Standards, at the address shown below.
This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above
address or at 610-832-9585 (phone), 610-832-9555 (fax), or [e-mail] (e-mail); or through the ASTM website
(www.astm.org).
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
E1689 – 95 (2008)
8

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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)
LOG OF SOIL BOR ING : SB -03
(Page 1 of1)
Project Name: Date Started : 10/23109 Driller : J, Aguire
Date Completed : 10123/09 Depth to Water : NA
Santa Fe River Assessment Drilling Method : HSA (7·3/4 0 0) Logged By : E. Romesser
Sampling Method : continuous (5' interval) X Coordinate : 1731486.02990
Project #: NME-VR2-SR Drilling Company : Rodgers & Co .• Inc. Y Coordinate : 1705469.01180
.. ~ 2
Depth E
" ;n Q.
Feet E ~ <J)
'--
10-
f-
15-
20-
25-
r-
30-)
0 E " Co !!; .e, DESCRIPTION c 0 " a: CL
SILTY SAND trace Cobbles, brown (5YR 4/6)
NA NA
60/24
30/30
60/43
60/48
60/44
60129
<1
Fill: SILTY SAND little Gravel (up to 2"), dark brovm (7.5YR 3/2), fine to medium gravel, coal & brick
pieces
SAND some Gravel & Cobbles, reddish (2.5YR 7/6), fine-to
gravel & cobbles
Not : boulder, augered down to 11.5' bgs
Tesuque lormation contact
sand, fine to coarse
<1 SAND, reddish (2.5YR 7/6), fine-grained sand (little medium grained), subangular, moist
SAND, reddish (2.5YR 5/8), fine-grained sand, subangular, dry
SAND trace Gravel, reddish (2.5YR 4/8), fine-to coarse-grained sand, subangular, fine gravel.
<1 subangular
['-SAND little Gravel, reddish (2.5YR 4/8), fine-to coarse-grained sand, fine gravel, strongly cemented,
laminar layers al -12" from bottom
<1
<1
<1
SAND, reddish (2.5YR 4/8), fine-to coarse-grained sand, subangular to subrounded, 2" cobble, dry
SAND little Gravel, reddish (2.5YR 4/8), fine-to coarse-grained sand, subanglar to subrounded, fine to
coarse gravel, subangular to subrounded, strongly cemented, dry
SAND little Gravel, reddish (2.5YR 4/8), fine-10 coarse-grained sand, subanglar to subrounded, fine to
coarse gravel, subangular to subrounded, strongly cemented, 2" cobbles, dry
SAND little Gravel, reddish (2 .5YR 4/8), fine-to coarse-grained sand, subanglar to subrounded, fine to
coarse gravel, subangular to subrounded, strongly cemented, 2" cobbles, dry
u
I <J) CL u « <J) a:
::> '"
SM
\) i<
1 + Iii
I> swl <
••••••••••• i
>
Y
..... :.:
~ SP }< I sand, very Ihin laminar I SAND, reddish (2.5YR 4/8),
35 _r-...l.L..'B_I2_4-,-_<_'-\l ~~~~~~, ;"".::.,~,e~ 2~d"d~ sips~li!.i'tt ~~1De! .. 05 ~oYI!&nIR)4_1_8)_, _fin_e_-_to_co_a_rs_e_-9_r_a_in_ed_sa_n_d_, _sU_b_a_n_9U_I_ar_, _st_ro_n_9_IY_C_e_m_e_n_te_d_ls_a_m_p_le __ .-J_ SW..L."-..-j
Bottom of Boring at 35.5' bgs
40
Notes:
~! 1. Post hole 0-4' bgs.
5. Groundwater not encountered · monitoring well not installed. Soil boring
abandoned with bentonite/cement slurry on 10123109.
2. NA:: Not Applicable.
3. Refusal at 35.5' bgs, Splil Spoon: blow counts 15·69·175.
4. X = Sample interval sen! for laboratory analysis.
LOG OF SFRMW-01
(Page 1 of 1)
Project Name: Date Started
Date Completed
Drilling Method
Sampling Method
Drilling Company
: 10/20/09
: 10/20/09
Driller
Santa Fe River Assessment : HSA (7-314 00)
Depth to Water
logged By
Project #: NME-VA2-SR
: continuous (5' interval)
: Rodgers & Co., Inc.
X Coordinate
Y Coordinate
Depth
;n
Feet
o
5-
10-
15-
20-
25-
30-
35-
~ Notes:
'" "-E '" <f)
-
NA NA
60110 <1
60/18 <1
60/32
60/19
60/36 3.0
30118 1.1
o 1. Post hole 0-4' bgs.
DESCRIPTION
Cuttings: SAND wI Gravel, trace cobbles, dark brown (7.5YR 3/2), fine-grained
sand, fine to coarse gravel, road-base engineered fill, dry
SAND trace Gravel, brown (5YR 4/2), fine-to medium-grained sand, line to
coarse gravel, subangutar, dry
SAND trace Gravel, brown (5YR 4/2), fine- to medium-grained sand, fine to
coarse gravel, subangular, subangular cobbles, dry
SAND trace Gravel, reddish-brown (5YR 5/6), fine-to medium-grained sand,
subangutar, fine gravel, subangular, dry
Tesuque formation contact
SAND, whitish brown (1 OYR 8/3), fine-grained sand, subangular, dry
SAND, same as previous; reddish brown (5YR 7/8), fine-grained sand,
subangular, moist
SAND, reddish brown (5YR 6/8), fine-grained sand, subangular, wet
SAND, reddish brown (5YR 5/8), fine-grained sand, subangutar, saturated
SAND, reddish-brown (sYR 5/8), medium-to coarse-grained sand, subangular,
saturated
Bottom of Boring at 31 .5' bgs
~. 2. NA:= Not Applicable.
" 3. X:= Sample interval sent lor laboratory analysis.
g 4. -:= PID mailunction.
u I
<f) "-U <t <f) a: :0 (!J
SP
t,
t>
I: Ii
: J. Aguire
: 21' bgs
: E. Aomesser
: 1731606.54850
: 1705086.39280
SFRMW-Ol:
Flush Grade,
24" Oia. Flush
Concrete Pad
~-L:;~ locking Well Cap
I--Y .::
t-Bentonite
Grout
~+-2" SCH.40 .. PVC Casing
v
V t-Bentonite V Plug
.::1-10-20
Silca Sand
Filter
. -0.020"
Screen
FIELD GUIDE FOR
SOIL AND STRATIGRAPHIC ANALYSIS 11.2
DENSITY OR
CONSISTENCY
COARSE
GRAINED
DEPOSITS
N-VAlUE ~ ~ VERY LOOSE
5-10 ~ LOOSE
11·29 .. MEDIUM DENSE
30-49 .. DENSE
>50 .. VERY DENSE
FINE
GRAINED
DEPOSITS
N-VALUE ~
34
5-8
9-15
16-30
>30
,-__ ...r:==YE~S--"".( MATRIX COLOR
IS THE COLOR Ust in sequence, dominant fitst
A MATRIX COLOR?
qu (ts~
<0.25
0.25-0.50
0.50-1.0
1.0-2.0
2.0-4.0
>4.0
• VERY SOFT • SOFT
• MEDIUM • STIFF • VERY STIFF • HARD
COAnNG or CONCENTRAnON
Note frequency, color, and size
NO IS THE COLOR FROM A COAnNG (MOTTLE --.....,
OR CONCENTRATION? NO ..... ~ote contrast. color, and size ~ CLASSIFICAT::IO:N=-------~~~~~~~~~~~~~~~~~==~=:==::=:~~~~~~::::::~-l
u-.&d Sol ~ $)'SUm. 8dapIId ASlll 02468 STEP 3:
c;oHnNUE """ .!AHD ORGRAV£t.
ONFtOW(;HART
""""SEJ
MOISTURE
PLASTICITY 1\IM_~fIOHJ
COHESIVENESS
SEDIMENTARY
STRUCTURE
WEATHERING
ZONE
ABBREVIATION
SECONDARY
GRAIN SIZE
INFORMATION
DEPOSITIONAL
ENVIRONMENT
NAME
STRATIGRAPHIC
CONTACT
DEPOSITS
NON PLASTIC LOW PLASTICITY
STEP 3:
OONnNUe """ GROUP SYMBOL
ONFtOWCHART -
MOISTURE ABSENT
OAMP
VISIBLE WATER
.. DRY
.. MOIST
• WET
FOR
NON-PLASTlC
FINES
WATER RISES TO SURFACE SLOWLY .. SLOW OILATENCY
WATER RISES TO SURFACE QUICKLY'" RAPID OILATENCY
WlLL NOT SUPPORT 6mm DIAMETER ROll IF HELD ON END
6mm DIA. ROLL CAN BE REPEATEDLY ROllED ANE) SUPPORTS ITSELF, 4mm DIA ROLL DOES NOT
4mm DIA. ROLL CAN BE REPEATEDLY ROLLED AND SUPPORTS ITSELF, 2mm DIA ROLL DOES NOT
2mm DIA. ROLL CAN BE REPEATEDLY ROLLED AND SUPPORTS ITSELF
6mm DIAMETER ROll CANNOT BE FORMED ~ NONCOHESIVE
6mm DIAMETER ROLL CAN BE FORMED ~ COHESIVE
UNIFORM
BEDS >30cm
BEDS 3cm 10 30cm
BEDS O.Scm to 3cm
BEDS <O.Scm
~ MASSIVE
~ THICKLY BEDDED
.. BEDDED
.. THINLY BEDDED
~ LAMINATED
SECONDARY
SOIL
STRUCTURE (lH sow .. OHL Y)
Spheroidal peds or granules usually
packed loosely
Irregular, rotJ9hly cube/ike peds with
planar faces (angular or subangular)
Flat and horizontal peds
Vertical, pillarlike peds with flat tops
MODIFIER SYMBOL 1st SYMBOL 2nd SYMBOL LAST SYMBOL ~-['_
MOntED • M OXIDIZED ·0 LEACHED .L SECONDARY
JOINTED • J REDUCED ·R UNLEACHED ·U CARBONATE .2
UNOXIDIZED ·U
<5% • TRACE • • UTILE • UNIFORM ~ MEDIUM-GRAINED SAND 6% to 15% (poorly 9mded) 16% to 30% • FEW .. COARSE-GRAINED SAND • NON·UNIFORM .. FINE GRAVEL 31% 1049% • SOME (well graded) ~ COARSE GRAVEL
~ NON-PLASTIC
~ LOW PLASTICITY
~ MEDIUM PLASTICITY
~ HIGH PLASTICITY
~ GRANULAR
~BLOCKY
~PLATY
~PRlSMATIC
~COLUMNAR
EXAMPLE ! ~~JL ~fJU
MOJL2 RU
MOJU UU
FOR GLACIAL .. CLAST FRACTION
OIAMICTONS ~ CLAST LITHOLOGY
• VARIOUS ~
DEPOSITIONAL ..
ENVIRONMENTS ~
(interpretation) .. •
EOUAN (LOESS)
FLUVIAL
ALLUVIAL
LACUSTRINE
COASTAL
RESEDIMENTED
GLACIAL
DEPOSmONAL
PROCESSES
.. SUBGLACIAL
.. GLACIOFLUVIAL
.. GLACIOLACUSTRINE
.. RESEDIMENTED
GENERALIZED
RESEOIMENTATION
PROCESSES
~ MASS SLUMP
.. SEDIMENT FLOW
.. COLLUV1UM
USE FORMAL STATE GEOLOGICAl SURVEY NOMENCLATURE WHEN POSSIBLE;
IF NOT POSSIBLE, ASSIGN SITE·SPECIFIC UNIT NAME ACCORDING TO DEPOSmONAl ENVIRONMENT I FACIES ASSEMBLAGE
< 10cm .. SHARP (or ABRUPT for pedogenic alternation)
> 10 em (Note transition interval) .. GRADATIONAL (or TRANSmONAL for weathering zone change)
midwest geosciences gtoup press
UNIFIED SOIL CLASSIFICATION SYSTEM
FOR COMMON INORGANIC AND ORGANIC SEDIMENTS
""""" .... ASTM
STEP 3: Llr~~~~~~~::::~~::::::~~~~~~~~~~~~~~~~~~!!~~~~~~~~!!!!!!!!~~!!~~~~O>nW~~"~E~""" 'SoVlO" OR "GRAVEl'
NlDFOUOWR.OWCHART
"'<=<iNA OR ..... """"'-(>50% coarse-grained, <50% fine sedments) NllJAGROI.JfJNAME
GROUP SYMBOL GROUP NAME
________ ~. -c:;w ~ <lS%.sand===~': WEU GRADED GRAVEL
<5% linn «::.=) ---. >15% sand .. WELLGRADEDGHAVELWlTHSAND
_______ _+_ .. GP ~<15"'sand .. POORLY GRADED GRAVEL P(u%~d ~ >15%RIKf .. POORLY GRADED GRAVEL WITH SANO
Gravel
(gravel> sand)
non-pIasllc fines-. GW.GM <::::: <15% sand _~~j'~ WELL GRADED GRAVEL WITH SILT We. graded < >15% sand .. WELLGRADEDGRAVELWlTHSILTANOSAND
< (I1OfHJnifonn) plutieftnes --. GW-GC ~ c15%sand II WELL GRADED GRAVEL WITH CLAY
10%&tes ---. >15% sand .. WELL GRADED GRAVELWlTH CLAY AND SAND
~mes----" GP-GM <:::!. <15%sand .. POORLY GRADED GRAVEl WITH SILT ~_ < >15% sand .. POORLY GRADED GRAVEL WITH SILT AND SAND
(unifotm) _Ii ------+ GP-GC ---"" c15%aand .. POORLY GRADED GRAVEL WITH CLAY
nas ---.... ,.15% sand .. POORLY GRADED GRAVELWfTH CLAY AND SAND
non-pI.ulk:fInes---+-GM ________ <15%5300 ~~~~. SILTY GRAVEL _=:::::====: ----. >15%sand .. SILTY GRAVEL WITH SAND ,. 15%fine3 plasllc fines --+-GC ________ <15%.sand .. CLAYEY GRAVEL
---.. >15% sand .. CLAYEY GRAVEL WITH SAND
Well graded ________ -1 •• SW _______ <15% gravel " WELL GRADED SAND
<5%finas < (norHJniIomI) ---. »15%grevel .. WEU GRADED SAND WITH GRAVEL
________ ... SP --==== <lS%gravel II POORLY GRADED SAND p{u~=~ >15% gravel .. POORLY GRADED SAND WITH GRAVEL
Welgraded < . --.... :>lS%gravel .. WEll GRADED SAND WITH SILT AND GRAVEL
Sand
(sand> gravel)
non-plaslic l'ines~ SW-SM ______ <15".4 gravel ~~~~. WELL GRADED SAND WITH SILT
(
cnon-untorml plasllcllnes ------.. SW-SC ~ <lS%OfirYei .. WEU GRADED SAND WITH CLAY
10% fines ---. >15%gravel ., WELL GRADED SAND WITH CLAY AND GRAVEL
non-plas1ic lines _______ SP-SM ---"" <15% gravel .. POORLY GRADED SAND WITH SILT
Poorly graded< --.. :»15%gravel .. POORLY GRADED SAND WITH SILT AND GRAVEL
(uniform) plastic fines -.. SP-SC ______ <15% gravel .. POORLY GRADED SAND WITH eLA Y
----.. >lS%gravel .. POORLY GRADeD SAND WITH CLAY AND GRAVEL
--+-<15% gravel .. SILTY SAND ~=:::::====+= non-plastlc lines ---+-8M ----..,. 15% gravel-------+-SILTY SAND WITH GRAVEL ~15%nnoG_ ... ~dc lines -----+ SC ~ <15% gravel .. CLAYEY SAND
----",,'5%gravel .. CLAYEYSANDWITHGRAVEL
INCR EASING
NON PLASTIC LOW PLASTICITY
()o50% f'ines, <50%
STEP 4: Does OR
INFLUENCE
""
. -.~~ '" '. '::" '~' '
". 1;'1 GROUP NAME
NO less than 30% Coars~ < 15% Coarse-Grained Sediment .. SILT
II <Grained Sediments ---... '5 25-C G ' dS d" ~%sand>%gravel .. SILTW!THSAND J L " 10 oarse-rame e Iment ---. % sand < % gravel ----+-SILT WITH GRAVEL
I % sand> % of ravel ... <15% gravel .. SANDY SILT morethan30%Coa~ 9 .... >15%gravel .. SANDYSILTWlTHGRAVEL
Grained Sediments -----.... : <15% sand II GRAVELLY SILT
% sand < % gravel _ >15% sand .. GRAVELLY SilT WITH SAND
less than 30% Coars~ < 15% Coarse·Grained Sediment .. lEAN CLAY <Grained Sediments----.... 15.25%Co .G" dS d' ,--'"" % sand> % gravel ----+-lEAN CLAY WITH SAND
CL arse rame e Imen .......... % sand < % gravel ------lIP-LEAN CLAY WITH GRAVEL
0;' d % t I :: <15% gravel .. SANOY LEAN CLAY I morethan30%Coa~ osan > 0 grave ->15%gravel .. SAHOYLEANCLAYWITHGRAVEL
GrainedSedimenls -----.... : <15% sand .. GRAVELlYLEANCLAY
% sand < % gravel _ > 15% sand II GRAVELLY LEAN CLAY WITH SAND
less than 30% Coarse ~ < 15% Coarse-Grained Sediment .. FAT CLAY <Grained Sediments ~ 15.25% Coarse-Grained Sediment ..-. % sand> % gravel .. FAT CLAY WITH SAND
CH ~%sand<%gravel ~FATCLAYWlTHGRAVEL
% d 01 f I :: <15% gravel .. SANOY FAT CLAY morethan30%Coarse~ san > ,00 grave >15% gravel .. SANOY FAT CLAYWlTH GRAVEL GraJned~edjments <--... : <15% sand .. GRAVELLY FAT CLAY
%sand <%gravel _ >15% sand II GRAVELlYFATCLAYWITH SAND
less than 30% Coarse ~ < 15% Coarse-Grained Sediment ~ ORGANIC SOIL
OL I OH ~ % sand < % gravel -.... ORGANIC SOIL WITH GRAVEL < Grruned Sediments <---.... 15.25% Coarse-Grained Sediment .-. % sand~ % gravel.-+ ORGANIC SOIL WITH SAND
% sand> % of ravel " :: <15% gravel .. SANDY ORGANIC SOIL morethan30%Coars~ -g ~15%graVel II SANOY ORGANIC SOIL WITH GRAVEL
Grained Sediments <--... ~ <15% sand II GRAVELLY ORGANIC SOIL
ASTMcharureptinl.edwiUrpemilSSlOO % sand < % gravel lIP ~15% sand II GRAVELLY ORGANIC SOIL WITH SAND
copyright ZOO1-2006111itM$1 gecsdenc:es ~ fJfUS
Bore Hole No. :
WMMW-16
PT" IIect White Mesa Sll!!ace Elev. 5587 est T. D, = 91.5 UMETCO Minerals Corporation
_Dat.~ 12107/92 De pth to Water: Dry Geolo~ist:_ F. A. Peel
I ....... " •• "" .... ~ Well
Gamma (Nat) Depth iii Neutron· API
10 ~ I~~ 0 7000
Sample Description ~ructlQn -
114"51 .. --~ &.i_e.g
~ ~ ~
Soil
Fm .....••..
o L\{} l±4.
--
........... r·············· -t:':':':':':':j'" •••• ••• I··· .. ·· ... ~ ~
,,", "IF .,
Pili ....... : ............... .
t----r--+-----I"H .J
(
... ) . ., ... -r ............. .
S '" ~'.' BUrro Canyon Fm 1_ '':'
~ I'~~'. r---~\+----4 v _
··f······ .. ·····
..................
7~ :
(
..................
gO-= B-ushV Basin Member -
C)f"st1
r.... ~.5' Slndllone: qu.nz. ighI butt 10 io;;1l qray, -r In.-10 lin.-grar..d.ka:>lrili:, me ....... 10 lhi1 bedd..:!,lro<!oJh acq bedding II" -=-potO&iIy,
Cayala1r. liqhl gray,~. aio;t1\1y undy,"" cart>cNoeaJ. poI1inqa, hard.
~
Slndlione: quer1z, IighI qray, -r line gr-..d, .. brtu>ded. Ioa:>nllc, Ihi! ClOG ~. achedJ. <60 PVC' r-bedding. hMI.
~(e_~ It Slndllone: ,quer1z, ~I yelow gray, liM 10 medium grained, w.n:..nd..:! lo!<IUnd I(.~, 1 E~ an'uc
Mclinillc. It Iron stainmq. Ihin aoeo bedding.
. ••..•••••• 1 •••..••• :-(-
)
Slrdllone: qu.nz. ~ q'lI)'. modiJrn 10 ..,... qnin.:!, .aclnlc, ~a1ic peCCI .... A'1QU~ lil/lie'rag __
J Slrdllone: qu.nz. ighI q,lI)'. lin. 10 rnodIurn-qraned, subocund 10 !<lUnd..:!,
(
;' Conglomeral.: ~ qra)', ang""" 10 .. bangu~, mer!' undllon. c:IMIs.
.. -..... · .. ·1-·\-1····,·····,
1"""':"'1'" ••••••
. ... , ..... ·-!-··I···· ...
I)
\
SillJ1ooa: g-nsh g'ay,sardy i! part, occaion. mn llain~ •
Slnd_: quer1z, ~ q..n.l!qray. very IIn.qnined oily.
511.: g"'-' ;ray, 'Mbedded d. bmoniIi:.
Slndllone: qu.nz. /igI1' butt 10 light;,.,., -r .... qrainad, .. b anglliar.l..,. n-.gran""', pcrooiIy, irn:ri. a>n::nNIliOna, \race iron alaining.
Slrdslone: quer1z, io;;1ll>rDwrBh gray. line II' ainad. Chin CICU beddng. rr.:.. ~. boecormIing qreenw, 11'11)' 'lOry , ... qrained '"",lid ba .. ,,,,,, porln;lal 64'
Slndllone: quer1z, ignl gray. rn.:fiJrn qrained, .. b.o"9J~ 10 .. boInI, w"
:!aIed. kaclinili:. pocr 10 geed nMllfIll .... r pcmsiIy, oa;,uional O)arse sond
( groins ard pebble ~a1. aImge<s, \rae. iron llaining.
.... ,/ S/uole: dart< gnI«1, !hinbaddod !lOll.
K..5.1E·5an'uc
Cenlraiat .
1(.7 .BE-S an'uc
10-20 Colora.
Sica Sind
K.2..9€-SCtn'sc:
Wei [)y
----
= == == == == == == --
~ ~ ~ ~ ~ ~ ~
"
~
W W IL.
Z
BORING NO. 19
EL. 5600.3 FT.
o ':.' ,'SMI ;:'. 'Ml . :" .
93/· '. 12.4'%-92 • 11"
10
15
20
25
30
7.0
35
rsJ 10
,':'::
.....
.~~~~~~~~~ S D S
~ ~~(. .mmm
50/
J;l. 4~"
98
71
RED-BROWN FINE SAND AND SILT,
MEDIUM DENSE
GRADING CALCAREOUS WTIH
CALCITE STRINGERS
GRADES VERY CALCAREOUS AND
VERY DENSE
BECOl1ES VERY LOOSE, POSSIBLY
t'IITH VOIoJS
BECOMES DENSE
GREEN, FINE TO MEDIUN-GRAINED
SANDSTONE, \~EATHE;RED, WITH SOME
ORA.'\IGE AND YELLOW IRON STAINING
GRAY-GREEN, FINE TO 11EOIUM GRAINED,
WEATHERED, CLAYEY SANDSTONE lVITlJ
ORANGE AND YELLOW IRON STAINIt-IG
BECOMES LESS WEATHERED WITH LESS
CLAY, PREDOl>IINANTLY GRAY WITH
ORANGE IRON S'I"AINING, MODERATELY
CEMENTED, MEDIUM GRAINED
BROWN-YELLOI'I, COARSE-GRAINED SANDSTONE
FINE GRAVEL CONGLOMERATE WITH CONSID-
ERABLE COARSE-GRAINED SAND AND CAL-
CAREOUS MATRIX
-40
::,:'.:: CGl
__ -+-:S:-5-t!:~~g~~!! SDS
~ t-n... w Q
943
45
50
.1. -,-
78
55 n
-'-
60
65
70
75
80
BROWN TO YELLOW, COARSE-GRAINED SAND-
STONE WITH CONSIDERABLE NEAR HORI-
ZONTAL FRACTURING AND SOME ORANGE
IRON STAINING, MODERATELY CEMENTED
WATER RETURN COMPLETELY LOST
LIGHT GRAY, MEDIUM TO COARSE-GRAINED
SANDSTONE; HIGHLY FRAC,TURED ALONG
HORIZONTAL BEDDING, CONSIDERABLE
LIMONITE STAINING ALONG BEDDING FRACTURES; MODERATELY CEMENTED TO
UNCEMENTED, CORE LOSSES ASSUMED
DUE TO WASHING AWAY OF UNCEMENTED
ZONES
LIMITED WATER RETURN
BECOMES VERY UNCE~!ENTED, WATER
RETURN LOST
HOLE LOST AT 72 FT; HOLE 19A
DRILLED 15 FT SOUTH OF HOLE 19;
NO WATER RETURN OBTAINED; NO
SAMPLING POSSIBLE; HOLE LOGGED
FROM DRILLING PROGRESS
VERY WELL-CEMENTED SANDSTONE (72 FT)
MODERATELY-CEMENTED SANDSTONE (73 FT)
LOG OF
80 ------.:c:r!
85 -----0{
90 -------1:
95------1:
100 ------1:
~ w W IL.
~105------~
~ ~ n... w Q
110 -----;:
115-----~
120 ------!= ........ .
125 -----oi
.........
130------
BORINGS
MODERATELY WELL-CEMENTED CONGLO~~RATE
OR FRACTURED SANDSTONE, GRADING BETTER
CEMENTED
GRADING LESS CEMENTED
VERY POORLY-CEMENTED SANDSTONE
MODERATELY-CEMENTED CLAYSTONE
POORLY-CEMENTED SANDSTONE WITH
MINOR HARD LENSE;S
MODERATELY-CEMENTED SANDSTONE
GRADES LESS CEMENTED
APPEARS CLAYEY
MODERATELY-CEMENTED SANDSTONE
GROUND WATER LEVEL 110 FT, 11/4/77
POORLY-CEHENTED SANDSTONE WITH
OCCASIONAL BANDS OF GRAVEL OR
CONGLot-1ERATJ:
VERY WELL-CEMENTED SANDSTONE
VERY POORLY-CE~1ENTED SANDSTONE
VERY WELL-CEI1ENTED SANDSTONE
BECOMES LESS CEMENTED AND CLAYEY
HOLE COMPLETED 9/25/77
DAMES e. r...OORE