DRC-2009-004036 - 0901a06880140a21

INFILTRATION AND CONTAMINANT TRANSPORT
MODELING REPORT
WHITE MESA MILL SITE
BLANDING,UTAH
DENISON MINES (USA)CORP
November 2007
Prepared for:
Denison Mines (USA)Corp.
1050 17th Street,Suite 950
Denver,Colorado
80265
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PreparHt'by:
MWH Americas,Inc.
10619 South Jordan Gateway,Suite 100
Salt Lake City,Utah
84095
TABLE OF CONTENTS
SECTION
EXECUTIVE SUMMARY
1.0 INTRODUCTION
1.1 Objectives oflnfiltration and Contaminant Transport Model
1.2 Permit Requirements
1.3 Document Organization
2.0 BACKGROUND
2.1 Site Overview
2.1.1 Facility Description
2.1.2 Tailings Cover Design
2.1.3 Tailing Cell Liner System
2.104 Characteristics ofTailings
2.2 Site Characteristics
2.2.1 Climate
2.2.2 Summary ofSite Geology
2.2.3 Site Hydrogeology
2.204 Groundwater Quality
2.2.5 Vadose Zone Characteristics
2.3 Vadose Zone Flow and Transport Conceptual Model
2.3.1 Unsaturated Flow
2.3.2 Contaminant Transport in the Unsaturated Zone
3.0 METHODOLOGY
3.1 Overall Modeling Approach
3.2 Vadose Zone Flow and Transport Model
3.2.1 Computer Code
3.2.2 Domain
3.2.3 Finite-Element Node Spacing
3.204 Boundary Conditions for the Vadose Zone Flow Model
3.2.5 1nput Parameters for the Vadose Zone Flow Model
3.2.6 1nitial Conditions for the Vadose Zone Flow Model
3.2.7 Boundary Conditions for the Vadose Zone Transport Model
3.2.8 Input Parameters for the Vadose Zone Transport Model
3.2.9 Initial Conditions for the Vadose Zone Transport Model
3.2.10 Duration of Simulations and Time Steps
3.2.11 Sensitivity Analysis
3.3 Groundwater Flow and Contaminant Transport Modeling
3.3.1 Model Codes
3.3.2 Model Domains,Layering,and Grids
3.3.3 Boundary Conditions
3.304 Hydraulic Properties
3.3.5 Calibration ofFlow Models
3.3.6 Contaminant Transport Model
PAGE
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2-14
2-17
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3-1
3-3
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3-5
3-5
3-6
3-8
3-11
3-11
3-11
3-13
3-14
3-14
3-16
3-16
3-17
3-17
3-19
3-20
3-21
TABLE OF CONTENTS
(continued)
SECTION
4.0 RI~SULTS
4.1 Tailings Cell Cover System Modeling
4.2 Tailings Cell Dewatering Modeling
4.3 Tailings and Vadose Zone Flow and Transport Modeling
4.3.1 Saturated Thickness ofTailings and Flux Rates Beneath
Tailings Cells
4.3.2 Contaminant Concentrations and Mass Flux Rates
4.3.3 Sorption,Retardation and Potential Migration of
Other Contaminants
4.4 Groundwater Modeling Results
4.4.1 Groundwater Flow Model Calibration
4.4.2 Contaminant Concentrations and Distribution in Groundwater
4.5 Sensitivity Analysis
4.6 Uncertainty and Assumptions
5.0 CONCLUSIONS AND POST-AUDIT MONITORING PLAN
5.1 Conclusions
5.2 Post-Audit Monitoring Plan
REFERENCES
LIST OF APPENDICES
PAGE
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4-2
4-3
4-4
4-5
4-8
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4-10
4-12
4-14
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5-1
5-6
R-I
APPENDIX A
APPENDIX B
APPENDIXC
APPEND1X D
APPENDIX E
Unsaturated Hydraulic Properties for Cores from White Mesa
Speciation and Surface-Complexation Modeling ofTailings Porcwater
HYDRUS-1D Modeling Files (electronic files on DVD)
PHREEQC Modeling Files (electronic files on DVD)
MODFLOW and MT3DMS Modeling Files (electronic files on DVD)
11
TABLE
NO.
2-1
3-1
3-2
4-1
4-2
4-3
TABLE OF CONTENTS
(continued)
LIST OF TABLES
(Tables at end of respective section)
TITLE
Unsaturated Hydraulic Propertics for Cores from White Mesa
Saturated and Unsaturated Hydraulic Properties of the Whitc Mesa Mill
Vadose Zonc Flow Model
Physical and Chemical Propclties of the White Mesa Mill Vadose Zone
Transport Model
Distribution (K,,)Coefficients and Retardation Factors (R)for Selected
Contaminants Present in the Tailings Pore Fluids White Mesa Mill Vadose
Zone
Model-Predicted Chloride and Sulfate Concentrations in Groundwater
Model-Predicted Chloride Concentrations at the Bottom of the Vadose
Zone for Cells 1 and 3 Evaluated as Part of the Sensitivity Analysis
HI
FIGURE
NO.
2-1
2-2
2-3
2-4
2-5
3-1
3-2
3-3
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
TABLE OF CONTENTS
(continued)
LIST OF FIGURES
(Figures lit end of respective section)
TITLE
Site Map
Generalized Cross Section with Modified Cover Design
Annual Precipitation at Blanding,Utah (1905-2005)
Daily Precipitation at Blanding,Utah (1905-2005)
Piezometric Surface Contours Perched Aquifer (September 2002)
Modeling Approach and HYDRUS-ID Model Domain and Boundary
Conditions
MODFLOW Tailings Cell Model Domain,Grid,and Boundary
Conditions
Perched Aquifer Model Domain,Grid and Boundary Conditions
Model-Predicted Water Flux Rate Through Tailing Cell Cover
(Typical 57-Year Period)
MODFLOW Model-Predicted Saturated Thickness of Tailings in Cells 2
and 3 Assuming Continuous Dewatering Pumping
Model-Predicted Saturated Thickness (Pressure Head)of Tailings Above
the Liner (Post-Dewatering)
Model-Predicted Water Flux Rates Through the Vadose Zone Beneath the
Tailing Cells
Model-Predicted Chloride Concentrations in Vadose Zone Pore Water
Immediately Above the Perched Aquifer Beneath Cells 2 and 3
Model-Predicted Chloride Concentrations in Vadose Zone Pore Water
Immediately Above the Perched Aquifer Beneath Cells 4A and 4B
Model-Predicted Sulfate Concentrations in Vadose Zone Pore Water
Immediately Above the Perched Aquifer Beneath Cells 2 and 3
Model-Predicted Dissolved Uranium Concentrations in Vadose Zone Pore
Water at 200 Years
MODFLOW Model-Predicted Piezometric Surface Contours Perched Aquifer
IV
flgll
ADE
amsl
bgs
em/sec
DoD
DRC
ET
FML
ftlft
GMS
GWCL
GWQS
HDPE
lIFO
L
mgll
MWII
PE
PET
PT
PVC
RMSE
TDS
u.s.EPA
USGS
LIST OF ACRONYMS
micrograms per liter
advection dispersion equation
above mean sea level
below ground surface
centimeters per second
Department of Defense
Division ofRadiation Control
evapotranspiration
flexible membrane liner
foot per feet
Groundwater Modeling System
Ground Water Compliance Limits
Ground Water Quality Standards
high-density polyethylene
hydrous ferric oxide
length
milligrams per liter
MWII Americas,Inc.
potential soil evaporation
potential evapotranspiration
potential transpiration
poly vinyl chloride
root mean squared errors
total dissolved solids
United States Environmental Protection Agency
United States Geologic Survey
v
EXECUTIVE SUMMARY
This document presents the results of infiltration and contaminant transport modeling to
support Denison's Groundwater Discharge Permit (Ground Water Quality Discharge
Permit No.UGW370(04)(the "Permit")for its White Mesa uranium milling and tailings
disposal facility.The White Mesa Mill (the "Mill")is located in southeastern Utah,
approximately six miles south of Blanding,Utah.As described in Part I.H.I!of the
Permit,Denison is required to prepare an infiltration and contaminant transport model.
The primary objective of the infiltration and contaminant transport model is to
demonstrate the long-term ability of the tailings cells cover system to adequately contain
and control tailings contaminants and protect nearby groundwater quality of the
uppermost aquifer.
The computer code HYDRUS-I D was used to model potential infiltration and
contaminant transport through the cover system,tailings,tailings cell liner system,and
through the underlying bedrock vadose zone.HYDRUS-ID is one of the few
commercially available,frequently testcd models that can simulate both unsaturated now
and contaminant transport in the vadosc zone (including layered stratigraphy)with a
variety ofinitial and boundary conditions.
The computer codes MODFLOW and MT3DMS were used to model groundwater flow
and potential eontaminant transport in the perched aquifer.These models were selected
because they can adequately represent and simulate the hydrogeologic conditions and
contaminant-transport processes that could potentially occur in the perched aquifer
beneath White Mesa.Furthennore,these models are well-documcnted,trcquently used,
and versatile programs that are widely accepted by the scientific and regulatory
communities.MODFLOW was also used to evaluate dewatering in Cells 2 and 3.
The Mill includes a mill facility and tailings cells located south of the Mill.The tailings
cells comprise the following:
ES-I
Cell I --55 acres,used for the evaporation ofprocess solutions
Cell 2 _.65 acres,used for storage of barren tailings sands
•Cell 3 _.-70 acres,used for storage of barren tailings sands and evaporation of
process solutions
•Cell 4A -40 acres,currently unused,but is planned to be used for storage of
banen tailings sands and evaporation ofprocess solutions
Cell 4B-yet to be constmeted (approximately 40 acres),but is planned to be
used for storage of ban'en tailings sands and evaporation of process solutions.
The tailings cells generally were excavated into the underlying Dakota Sandstone and arc
separated by dikes composed of compacted earthen materials covered with a liner.In the
vicinity of the tailings cells,the perched watcr table is approximately 75 to 115 ft below
ground surface,which is 40 to 90 It below the bottom ofthe tailings cells.
Based on improvements to cover design technology since the original design was
proposed,the cover design for the tailings cells can be modified slightly for improved
performance.These modifications arc:
Replacing the cobble layer with 6 inches of topsoil with gravel and vegetation
consisting primarily of grasses (the cobble layer will be retained for side
slopes)
•Increasing the frost barrier/water storage layer from 2 to 3 ft.
This cover was tested with the vadose zone infiltration model and significantly improved
pcrformanee over thc original dcsign (average model-prcdicted long-term infiltration
rates were reduced from 1.0 x 10-2 cm/day for the original covcr design to
1.0 x 10A cm/day f()r thc modified cover dcsign,a reduction oftwo orders-of~magnitude).
The vegetation is expected to enhance evapotranspiration and to significantly reduce
infiltration of water into the tailings.As specified in Part LH.II of the Permit,the
Pennittee may include supplemental infonnation to justify modification ofcertain Permit
ES-2
requirements,including tailings cell cover system engineering design and construction
specifications.Upon Executive Secretary approval of the final infiltration and
contaminant transport repOli,the Reclamation Plan may be modified to accommodate
necessary changes to protect public health and the environment.In the modeling
performed and presented in this repOli,we have assumed that the cover design for the
tailings cells has been modified as described above.
The contaminants modeled included natural uraJ1lUJ1I,chloride,and sulfate.Thesc
compounds are the most dependable indicators ofsite water quality and of potential cell
failure due to their predominance (uranium)and predominance and mobility (chloride
and sulfate).In particular,because sorption of chloride is minimal,it will migrate
unretarded and act as a conservative tracer and thus would be expected to be detected
before all other contaminants,particularly uranium,which will sorb onto mineral surfaces
in the vadosc zone.
Modeling of the tailings dewatering system with MODFLOW suggcsts that it is not
practical to fully dcwater the tailings in Cclls 2 and 3.Modeling predicted that
dewatering rates would decline to approximately 2 gpm atter 10 and 14 additional years
of pumping from Cells 2 and 3,respectively,leaving 4 ft of saturated tailings on average.
The reduction in pumping rates is caused by thc reduction in saturated thickness of
tailings.Cells 4A and 4B have a more extensive slimes drain network and were assumed
to be dewatered after approximately five years given the more extensive drain network.
Following dewatering activities,modeling of potential now from the tailings through the
liner and underlying bedrock vadose zone was perfOlmed with HYDRUS-ID.The
model-predicted flux rate through the liner varies as a function of the head (saturated
thickness)above the liner.On average,model-predicted flux rates through the liner
exceed infiltration rates through the cover.For short periods,potential infiltration rates
through the cover are predicted to exceed potential flux rates through the liner,during
which times water levels temporarily increase in the tailings.However,the pressure head
(saturated thickness oftailings)is not predicted to exceed the initial water level in Cells 2
and 3 (122 em [4 ft])or Cells 4A and 4B (30 cm [I ft]).Thus the mode!prediets that
ES-3
water will not overtop the maxImum liner elevation (pressure head equal to
approximately 914 em [30 tiD,even without active dewatering.
Modeling of potential flow fi-om the tailings through the liner and underlying bedrock
vadose zone was performed with HYDRUS-ID_It should be noted that in performing
this modeling,we have assumed potential defects in tbe liner and have made other
assumptions that may overestimate any potential fluxes ii-om the tailings cells.In reality,
the actual flux rates may be lower than model-predicted values or there may be no flux at
all.Model-predicted potential flux rates through the bedrock vadose zone beneath Cells
2 and 3 decline rapidly from an initial rate of 9.0 x 10-4 em/day,then gradually decline to
2.5 x lOA cm/day at 200 years.For Cells 4A and 4B,model-predicted flux rates through
the bedrock vadose zone decline rapidly hom an initial rate of 5.2 x 10-4 cm/day,then
gradually decline to a steady-state rate of 1.4 x 10-4 em/day by approximately 175 years,
aftcr the tailings are predicted to have become unsaturated.
Modeling ofpotential chloride and sulfate transport from the tailings through the tailings
cell liner and bedrock vadose zone,using these assumptions,was also performed with
HYDRUS-]D.Beneath Cells 2 and 3,chloride and sulfate concentrations in porewatcr at
the bottom of the bedrock vadose zone are predicted,using these assumptions,to increase
to concentrations of 0.39 and 0.09 mgll,respectively,at 200 years.Beneath Cells 4A and
4B,chloride and sulfate concentrations in porewater at the bottom of the vadose zone are
predicted to increase to concentrations of 0.011 and 3.2 x 10-4 mgll,respectively,at
200 years.Chloride was assumed to migrate unretarded (i.e.,no sorption)through the
vadose zone.Sulfate was assumed to have a maximum retardation faetor of 1.07,such
that it is considered highly mobile,but it is slightly retarded relative to chloride.These
are the model-predicted ehloride and sulfate coneentrations in vadose zone porewater that
could potentially reach the perched aquifer,based on the assumptions used in the model;
however,these are not the predicted concentrations in groundwater.
Modeling of chloride ancl sulfate transport in the perched aquifer was performed with
MODFLOW and MT3DMS.The Permit stipulates that concentrations of contaminants
in groundwater monitoring wells shall not exceed specified Ground Water Compliance
ES-4
Limits (GWCLs).Downgradient monitoring wells with GWCLs specified in the Permit
include MW-S,MW-ll,and MW-12,located on the berm immediately south
(downgradient)of Cell 3,and MW-14 and MW-lS,located on the berm immediately
south (downgradient)of Cell 4A.Due to the low mass flux rates predicted to reach the
aquifer,model-predicted chloride and sulfate concentration increases at these wells due to
the tailings eells are insignificant,and fall far below laboratory detection limits.At 200
years,the modeled fluxes from the tailings cells arc predicted to increase chloride by lcss
than 0.03 %of the proposed GWCLs in all monitoring wells.The modeled fluxes from
the tailings cells are predicted to increase sulfate by less than 0.0002 %of the proposed
GWCLs.
Retardation rates for uramum (VI)were calculated based on equilibrium soil-water
partition coefficients (Kd)using the mass of hydrous-ferric oxide (lIFO)present in the
bedroek and the equilibrated solution compositions predicted with the geochemical code
PlIREEQC.Neutralization of the infiltrating tailings-pore waters and sorption of solutes
was determined with PIIREEQC.The masses of 111'0 and calcite were determined it)r
samplcs collected irom the vadose zone for core samples hom the Dakota Sandstone.
Through this method,a sorption value ft)r the Dakota Sandstone immediately beneath the
tailings cells was estimated to be 8.47 kilograms per liter.Assuming a volumetric
moisture content of7%,a retardation factor of2S1 was calculated.
Modeling of potential uranium transport from the tailings through the tailings cell liner
and into the vadose zone was perfOlllied with IIYDRUS-ID.Due to the strong sorption
and the resulting high-retardation coefficients,uranium is not predicted to migrate mueh
beyond 20 em (8 inches)below the liner system in 200 years beneath Cells 2 and 3 and
Cells 4A and 4B.At 30 em (I ft)below the liner at 200 years,dissolved-phase uranium
concentrations arc predicted to be 3.0 x 10-4 mgll beneath Cells 2 and 3 and 2.0 x 10-8
mgll beneath Cells 4A and 4B.No uranium is predicted to reach the perched aquifer
within 200 years.While there is some naturally-occuning uranium in the vadose zone
initially,the modeling assumed no initial uranium for simplicity,and because there is a
lack of data concerning background uranium and distribution of uranium in the vadose
zone_Dissolved uranium concentrations were assumed to rcmain at a concentration of
ES-S
94 mg/l in the tailings.Because uranium was predicted to migrate such a short distance
in the bedrock vadose zone,there appears to be no threat to groundwater posed by
uranium.
Sorption coefficients and retardation factors were calculated for contaminants of potential
concern to assess their potential transport through the bedrock vadose zone.Solutes
predicted to have high Kd values resulting in high retardation tactors and low mobility
include arsenic,beryllium,chromium,copper,lead,uranium,vanadium,and zinc.
Similarly to uranium,these contaminants are not predicted to migrate through the vadose
zone to the perched water table in 200 years,given their high retardation f[lctors.Solutes
predicted to have intermediate Kd values include cadmium,cobalt,manganese,
molybdenum,and nickel.These contaminants also are not predicted to migrate through
the vadose zone to the perched water table in 200 years.Solutes predicted to have low Kd
values include sclenium and sulfate;while iron,t1uoride,mercury,silver and thallium
were predicted to migrate unretarded,like chloride.This assumes that there is no
sorption or any other loss mechanisms such as degradation,precipitation,or other
transformations.Based on Kd values reported in Sheppard and Thibault (1990),
U.S.EPA (1996),and U.S.EPA (1999),sorption and retardation of cadmium,cobalt,
Iron,manganese,mercury,nickel,selenium,silver,and thallium are likcly to be
significantly larger than model-predicted values.As a result only chloride,sulfate,and
fluoride are predicted to migrate with little or no sorption.
Given the magnitude of model-predicted impacts to groundwater for chloride and sulfate
(minimal),the impact caused by the other mobile contaminant (t1uoride)was estimated.
Using dilution/attenuation of chloride from tailings fluids to groundwater as a proxy,the
concentration of fluoride was estimated.Because the monitoring well predicted to be
impacted the most by potential releases from the tailings cells is monitoring well MW-I2,
the fluoride concentration was estimated for this location.Assuming a dilution factor of
768,000,a fluoride concentration of0.002 mg/l was estimated for MW-12.The proposed
GWCL for fluoride in MW-12 is 2 mg/I.As a result,the predicted concentrations of
fluoride as well as other contaminants of concern are not predicted to exceed proposed
GWCLs at 200 years.
ES-6
Under Part I.D.6 (Closcd Cell Pcrformance Requircmcnts)of the Pcrmit:
"bcf()re reclamation and closure of any tailings disposal cell,the Permittee shall ensure
that the final design,construction,and operation of the cover system at each tailings cell
will comply with all requircments ofan approved Reclamation Plan,and will for a period
ofnot less than 200 years mcet the following minimum performance requirements:
a)Minimize infiltration of prccipitation or other surface watcr into the tailings,
including,but not limited to the radon barrier,and
b)Prevent the accumulation of leachate head within the tailings waste layer that
could rise above or over-top the maximum FML lincr clevation internal to any
disposal cell,i.e.create a "bathtub"effect.
c)Ensure that groundwater quality at the compliance monitoring wells docs not
exceed the Ground Water Quality Standards or Ground Water Compliance
Limits specified in Part I.C.l and Table 2 ofthis Permit."
Based on the model results prcscntcd in this rcport,all threc requircments are met by the
modified cover dcsign.
ES-7
1.0 INTRODUCTION
This document presents the results of infiltration and contaminant transport modeling to
support Denison Mines (USA)Corp.'s (formerly International Uranium (USA)
Corporation's)Groundwater Discharge Pem1it (Ground Water Quality Discharge Permit
No.UGW370004)(the "Permit")for its White Mesa uranium milling and tailings
disposal facility (the "Mill").As described in Pati I.H.!1 of the Pennit,Denison is
required to prepare an inflItration and contaminant transport model.
Denison has engaged MWH Americas,lne.(MWH)to work with Denison personnel to
develop the assumptions and data for the infiltration and contaminant transpOti model and
interpret the model results.
1.1 OB,mCTlVES OF INFILTRATION AND CONTAMINANT TRANSPORT
MODEL
The pnmary objective of the infiltration and contaminant transport model is to
demonstrate the long-term ability of the tailings cells cover system to adequately contain
and control tailings contaminants and protect nearby groundwater quality of the
uppermost aquifer.
1.2 PERMIT REQUIREMENTS
Pmi1.H.I!(lnflltration and Contaminant Transport Modeling Work Plan and RepOti)of
Denison's Permit presents the requirements for infiltration and contaminant transport
modeling,as summarized below.
An infiltration and contaminant transport modeling report that demonstrates the long-
term ability of the tailings cells cover system to adequately contain and control tailings
contaminants and protect nearby groundwater quality of the uppermost aquifer must be
submitted.This repmi shall demonstrate how the tailings cell engineering design and
speciflcatious will comply with the minimum performance requirements of Part 1.0.6 of
the Permit.The original pennit speeifled that a work plan also must be submitted tor the
I-I
infiltration and contaminant transpOli modeling.Denison submitted a work plan to the
Utah Division of Radiation Control (DRC)in September 2005.However,the DRC did
not review this work plan and removed this requirement fi·OIn the permit as stated in a
Ictter hom DRC Executive Secretary to Denison dated 3 November 2006.This letter
also specified that all modeling must be eompleted and a final report must be submitted
for Executive Secretary approval by I June 2007.Subsequently,Denison requested and
received approval for an extension of this submittal to I September 2007 and
subsequcntly extended this to 23 November 2007.
The infiltration and transport modeling repoli must describe:
Applicable and pertinent historic studies and modeling repOlis relevant to the
tailings cell cover design and tailings cell system performance.
•lnf<mnation necessary for infiltration and contaminant transpOli modeling,
including representative input values for vadose zone and aquifcr soil-water
partitioning (Kd)coefficients,tailings source term eoncentrations,vadose zone
and aquifer dispersivity,contaminant half-life or other rates of dceay,etc.If
any required information is not currently available,conservative assumptions
can bc uscd for the model input.
Computer models that will be used to simulate long-tcrm performance of the
tailings cclls cover systcm.Specific information on model design,including
governing equations and their applicability to site conditions,grid design,
duration ofsimulation,and selection oftime steps must be described.
The conceptual model used and justify why it is representative or conservative
of actual field conditions at the site.The conceptual model will identify thc
physical domain and geometries simulated including the tailings cell design
and construction,all boundary and initial conditions assigncd in the models.
How the infiltration and contaminant transport problem has been
conceptualized,planned,and executed to demonstrate compliance with the
requirements ofPart l.D.6 of the Permit.
1-2
Model results,model calibration,steady state conditions,sensitivity analyses,
post-model audit plan.
Additionally,Part 1.0.6 (Closed Cell Performance Requirements)of the Permit presents
requirements regarding performance requirements for closed cells at the facility,which
impacts both actual infiltration at the site as well as how this infiltration will be modeled,
as follows:
Before reclamation and closure of any tailings disposal cell,the Permittee
shall ensure that the final design,construction,and operation of the cover
system at each tailings cell will comply with all requirements of an approved
Reclamation Plan,and will for a period of not less than 200 years meet the
following minimum performance requirements:
Minimize infiltration of precipitation or other surface water into the
tailings,including,but not limited to the radon barrier,and
-Prevent the accumulation of leachate head within the tailings waste layer
that could rise above or over-top the maximum flexible membranc liner
(FML)elevation internal to any disposal cell,i.e.,create a "bathtub
effect".
-Ensure the gTOundwater quality at the compliance monitoring wells does
not exceed the Ground Water Quality Standards (GWQS)or Ground
Water Compliance Limits (GWCL)specified in Part I.C.I and Tablc 2 of
the Permit.
Further,Part Le.I (Permit Limits)ofthe Pennit includes the following:
The Permittee shall comply with the following GWCLs --contaminant
concentrations measured in each monitoring well shall not exceed the GWCLs
defined in Table 2 of the permit.Groundwater quality at the site must at all
times meet all the applicable GWQS and the ad hoc GWQS defined in R317-6
1-3
even though this permit docs not require monitoring fllr each specific
contaminant.
Part I.H.ll also states that "Upon Executive Secretary approval of the final infiltration
and contaminant transport report,the Reclamation Plan may be modificd to accommodate
necessary changes to protect public health and the environment."
This report has been prepared to comply with the Permit as described above.
1.3 DOCUMU:NT ORGANIZATION
The remainder ofthis report includes the following sections:
Section 2.0 -Site Background;descriptions of the site including tailings cell
cover and liner design,as well as tailings chemical and physical
characteristics,site geology and hydrogeology,conceptual model of water
flow and potential contaminant transport through the vadose zone.
Section 3.0 ...Methodology;descriptions of the vadose zone and groundwater
flow and contaminant transport models,input parameters and boundary
conditions,and modcling assumptions.
•Section 4.0 Results;descriptions of the results of the vadose zone and
groundwater flow and contaminant transport modeling and sensitivity
analysis.
Section 5.0 ...Conclusions;provides a summary with the conclusions of the
vadose zone and groundwatcr flow and contaminant transport modeling along
with recommendations for a post-audit monitoring plan.
Section 6.0···References.
Appendix A ...Laboratory report with unsaturated hydraulic properties for
cores fi-om White Mcsa.
1-4
Appendix B --Speciation and surbcc-complcxation modeling of tailings
porcwater.
Appendix C -HYDRUS-ID modeling files (electronic files on DVD).
Appendix D PHREEQC modeling files (electronic files on DVD).
Appendix E·-MODFLOW and MT3DMS modeling files (electronic files on
DVD).
1-5
2.0 BACKGROUND
This section provides information on the:
Site background including descriptions of the White Mesa Mill facility,
tailings cell cover design,and tailings cell liner systems;
Site characteristics including geology,hydrogeology,and vadose zone
characteristics;and
Conccptualmodcl of flow and contaminant transp0l1 in the vadose zone.
Site-specific studies and rep0l1s reviewed to prepare this modcling report included:
•Construction Report,Initial Phase ..Tailings Management System,White
Mesa Uranium Project,Blanding,Utah (D'Appolonia Consulting Engineers,
Inc.,1982)
Revised Construction Drawings,DMC White Mesa Mill,Cell 4A Lining
Systeln (Geosyntec Consultants,2007a)
•Analysis of Slimes Drains for White Mesa Mill -Cell 4A Computations
(Geosyntec Consultants,2007b)
Stockpile Evaluation Tailings Cell 4A,White Mesa Mill -Technical Memo
submitted to International Uranium (USA)Corporation (Geosyntee
Consultants,2006)
Hydraulic Testing at the White Mesa Uranium Mill Site,near Blanding,Utah
During July 2002 (Hydro Geo Chem,Inc.,2002)
Site Hydrogeology and Estimation of Groundwater Travel Times in the
Perched Zone,White Mesa Uranium Mill Site,near Blanding,Utah.(Hydro
Geo Chem,Inc.,2003)
2-1
Revised Background Groundwater Quality Report:Existing Wells for
Denison Mines (USA)Corp.'s White Mesa Uranium Mi11 Site,San Juan
County,Utah (INTERA,2007)
Reclamation Plan,White Mesa Mill,Blanding,Utah (International Uranium
(USA)Corporation,2000)
Environmental Report (International Uranium (USA)Corporation,2003)
•Evaluation for Potential for Tailing Cell Discharge -White Mesa Mill.
Attachment 5,Groundwater Information Report,(Knight-Piesold,1998)
Hydrogeological Evaluation of White Mesa Uranium MiJI (TITAN
Environmental Corporation,1994)
Tailings Cover Design,\Vllite Mesa Mill,Blanding Utah (TITAN
Environmental Corporation,1996)
Draft Ground Water Discharge Permit,Statement of Basis for a Uranium
Milling Facility at White Mesa,South of Blanding (Utah Division of
Radiation Control,2004)
Complete citations for these and other sources cited throughout this document are
provided in the References Section.
2.1 SITE OVERVIEW
2.1.1 Facility Description
The \\Illite Mesa Mill is located in southeastern Utah,approximately six miles south of
Blanding,Utah.The Mill includes a mi11 facility and four tailings cells located south of
the MiJI (see Figure 2-1).The focus of this repOJ1 is the tailings cells;for information
concerning site history or mi11ing operations,see the Reclamation Plan,Revision 3.0
(International Uranium (USA)Corporation,2000).
2-2
The tailings cells comprise the following:
•CellI -55 acres,used for the evaporation ofprocess solutions
Ccll2 -65 acres,used for storage ofbarren tailings sands
•Cell 3 -70 acres,used for storage of barren tailings sands and evaporation of
process solutions
Cell 4A ._.40 acres,currently unused,but is planned to be used for storage of
barren tailings sands and evaporation ofprocess solutions
Cell 4B -yet to be constructed (approximately 40 acres),but is planned to be
used for storage ofbarren tailings sands and evaporation ofprocess solutions.
The tailings cells generally were excavated into the underlying Dakota Sandstone and are
separated by dikes composed ofcompacted earthen materials covered with a liner.In the
vicinity of the tailings cells,the perched water table is approximately 75 to 115 ft below
ground surface,which is 40 to 90 ft below the bottom ofthe tailings cells.
The White Mesa Mill is a zero discharge facility;thus all liquids must be eliminated
through evaporation.Currently,Denison is actively evaporating process waters from
Cell I and Cell 3 only.Cell I is currently used as an evaporation pond only and will not
be used to hold solid tailings.Water removed from Cclls 2 and 3 by the dewatering
system will be discharged to Cell I and subsequently evaporated.As part of the closure
plan,sediment and evaporite crystals in Cell I will be removed and placed in Cells 2
and/or 3 prior to closure.Cells 2 and 3 will be filled with tailings and covered.Cells 4A
and 4B also are expected to be filled with tailings and covered.Descriptions of the
tailings cover and liner systems are provided in the sections below.
2.1.2 Tailings Cover Design
An engineered multi-layered cover will be installed over a portion ofCell I (Le.,Cell I-I,
where approximately 10 acres wilJ be filled with contaminated materials fi'om the Mill
site decommissioning)and the entirety ofCells 2,3,4A,and 4B.The multilayered cover
2-3
as presented in the Tailings Cover Design (TITAN Environmental Corporation,1996)
and the Reclamation Plan,Revision 3.0 (International Uranium (USA)Corporation,
2000)consists of a 3-ft thick (minimum thickness;expected to be much greater in some
areas)platfonn (e.g.,support or grading)fill layer composed of random fill,primarily
silty sand and sandy silt,the top I ft of which will meet compaction standards.The
purpose of this layer is twofold:to raise the base of the cover to the desired subgrade
elevation and to allenuate radon flux.Above the platfonn fill will be a 1-ft thick layer of
compacted clay.The purpose of this layer is to inhibit vertical infiltration and to
allenuate the upward flux of radon.The design also includes a 2-ft frost barrier
composed of sandy silt and silty sand overlying the clay layer and a layer of riprap on top
of the frost barrier layer (8 inches on the side-slopes).For additional information
concerning the currently approved tailings cells and cover design,sec the Tailings Cover
Design (TITAN Environmental Corporation,1996)and the Reclamation Plan,
Revision 3.0 (International Uranium (USA)Corporation,2000).
Based on improvements to eover design technology since the original design was
proposed,the cUITently approved cover design will be modified slightly for improved
performance (see Figure 2-2).These modifications are:
Replacing the cobble layer with 6 inches oftopsoil with gravel and vegetation
consisting primarily of grasses (the cobble layer will be retained for side
slopes)
•Increasing the frost ban'ier/water storage layer trom 2 to 3 ft.
This cover was tested with the vadose zone infiltration model (described in Section 3.0)
and significantly improved performance over the original design (average long-tenu
model-predicted infiltration rates were reduced from 1.0 x 10-2 em/day for the original
cover design to 1.0 x 10-4 em/day for the modified cover design,a reduction of two
orders-of-magnitude).The vegetation is expected to enhance evapotranspiration and to
significantly reduce the potential for infiltration of water into the tailings.Gravel is
included in the topsoil layer to improve durability and longevity.The increase in
thickness of the frost ban"ier/water storage layer is to allow additional temporary water
2-4
storage for uptake by vegetation.The thickness of the fi'ostlban'ier water storage layer
was based on the amount of water storage required during winter months when
evapotranspiration is minimal,and the expected rooting depth of grasses,which is
typically Jess than 3 ft (Kurc and Small,2004;Currie and Hammer,1979;Foxx and
Tierney,1987;Schuster,1964;Lee and Lauenroth,1994).Bolen et al.(2001)used a 3-ft
water storage layer in an ET cover tcsted in Monticello,Utah.
Numerous studies of vegetated "evapotranspiration (ET)"covers have illustrated the
effectiveness of vegetation at reducing deep drainage (through the cover system),
pm1icularly in arid and semi-arid regions (Albright et aI.,2004;Bolen et aI.,2001;FayeI'
and Gee,2006;Gee et al 1994;Scanlon et aI.,2005).Albright ct al.(2004)measured
infiltration rates ofless than 4.1 x 10'4 em/day for seven of 10 vegetated covers tested in
semi-arid regions over a four-year period.The cover tested at Monticello,Utah as part of
this study had no measurable infiltration (reported as 0.0 mm/year;implying less than
3 x 10'5 em/day)during this test.FayeI'and Gee (2006)measured less than 1.4 x 10-4
em/day for weighing lysimeters with vegetated covers at the Hanford,Washington site.
With vadose zone modeling,Khire et a1.(2000)predicted total annual percolation rates of
less than 2.7 x 10"cm/day for covers in a variety of climatic settings,assuming the water
storage layer is at least 60 em (2 ft)thick.
2.1.3 Tailings Cell Liner System
The tailings cell liner systems consist of a minimum of 0.5 ft of cIUshed sandstone
underlay,a 0.030 inch (30-mil)poly vinyl chlOlide (PVC)flexible membrane liner
(FML)(Cells 2 and 3),a I-ft thick liner protective blanket ofsilty sand soil,and a slimes
drain collection system ofperforated PVC pipe (see Figure 2-2)in a 1-ft layer of clean
sand.Rather than a single 30-mil PVC FML,Cells 4A and 4B will have a geosynthetie
clay liner overlain by two 60-mil high-density polyethylene (HDPE)geomembrane layers
separated by a geonet (woven geotextile)layer.Slimes drain systems are installed in
Cells 2,3,4A,and 4B.The slimes drains in Cclls 2 and 3 include both 1.5-inch and
3-ineh diameter slotted PVC pipe,installed in a loft thick clean sand layer above the
protective blanket.These lateral drains are installed on 50-ft centers parallel to the
2-5
southcm edge of the tailings cells and cover an area that is approximately 400 ft (north-
south)by 600 ft (cast-west).The slimes drains in Cells 4A and 4B arc on 50-ft centers
and are located beneath the entirety of the cells.Leak detection systems are installed
under the cells and are monitored weekly to ensure that leakage does not occur.Details
of the liner systems are provided in D'Appolonia Consulting Engineers (1982)for Cells 2
and 3,and in Geosyntec Consultants (2007a)for Cell 4A (Cell 4B liner design is
anticipated to follow same specifications as Cell 4A).
Using methods developed by Giroud and Bonaparte (1989)and Giroud et al.(1992),
Knight-Piesold (1998)estimated potential fluxes from Tailings Cell 3 at White Mesa
Mill.Theoretically,a geomembrane liner consists of an impermeable material that
should preclude leakage into the underlying vadose zone.However,the occurrence of a
limited number of manufacturing and installation defects is generally anticipated and
incorporated during assessment ofenvironmental impacts (Giroud and Bonaparte,1989).
Knight-Piesold considered potential flux through the liner due to:
•Assumed vapor diffusion
Assumed pinholes due to manufacturing flaws
Assumed larger defects resulting from seaming errors,abrasion,and punctures
during installation.
Using a combination of empirical and analytical equations,and assuming a certain
number of potential defects and defect sizes taken from the literature (Giroud and
Bonaparte,1989)and a head of 4 ft above the liner of the cell,Knight-Piesold (1989)
calculated a potential flux rate of4.6 x 10.4 em/day.lt should be noted that in performing
this modeling,we have assumed potential defects in the liner and have made other
assumptions that may overestimate any potential fluxes Ii'om the tailings cells.In reality,
the actual flux rates may be lower than model-predicted values or there may be no flux at
all.
Long-tenn compatibility of liner materials with the acidic tailings fluids is unknown;
however,short-term testing provides evidence that mechanical and hydraulic properties
2-6
of PVC and HDPE liners are not affected by acidic fluids (Mitchell,1985;Gulec et aI.,
2004;Gulec et aI.,2007).Tests performcd by Mitchell (1985)used a simulated leachate
from uranium mill tailings with a pH between 1.5 and 2.5.Both one-sided and two-sided
(immcrsion)tests were performed on HDPE and PVC liners with contact times of four
months.Mitchcll (1985)reported that mcchanical properties were impacted minimally.
Tests perfom1ed by Gulec et al.(2007)used acidic solutions with pH 2 and involved two-
sided immersion tests of HDPE liners with contact times of 22 months.Gulec et al.
(2007)reported no statistically significant changes to mechanical or hydraulic properties
ofliner materials tested.
Long-term perfolmance of the liner system on the ordcr ofhundreds of years is unknown,
but there is strong evidence that there has been no leakage from Cells 2 and 3 over the
past 25 years indicating the effectivcncss ofthc existing PVC liner system.Evidence that
the cells are not leaking includes:
No leakage indicatcd by the lcak detection systems
• No significant leakage indicated by the perched aquifer water table c1evations
• No significant lcakage indicated by water levels in the tailings cells
No tailings contaminants detectcd in groundwatcr at levels above natural
background levels (see INTERA,2007).
Givcn that Cells 2 and 3 have hcld tailings and fluids since 1983,the above lines of
evidence support the hypothesis that there has not been leakage.
2.1.4 Characteristics ofTailings
The tailings are generally silty sand but heterogeneous due to the placement process.
Based on grain-size analyses performed on the tailings,sand-sized particles are dominant
(55 percent on average)with the remainder being silt and clay sized particles (Colorado
School ofMines Research Institute,1978).Based on grain-size analysis of tailings at the
Moab UMTRA site,clay contcnt is likely on the order of 1 to 10 percent.Specifically,
2-7
tailings described as sand,slimy sand,sand-slimes,and slimes had average elay contents
of I,4,12,and 17 percent,respectively (U.S.Department of Energy,2003).
The tailings are initially saturated when placed but are dewatercd through evaporation
and pumping from the slimes drains system.
The tailings chemistry is a function of the feedstock materials processed and the mill
process reagents used in the extraction process.Tailings wastewater chemistry is based
on data collected between Septcmber 1980 and March 2003,as presented in the
Statement of Basis (Utah Division of Radiation Control,2004).The tailings fluids are
high in ammonia (average concentration of 3,131 milligrams per liter [mg/I]as N),
chloride (average conccntration of 4,608 mg/I),fluoride (average conccntration of
1,695 mg/I),sulfate (average concentration of 64,914 mg/I),and total dissolved solids
(TDS;average concentration of 85,960 mg/l).Metals concentrations in the tailings
wastewatcr that excccd Utah GWQSs inelude arsenic,beryllium,cadmium,chromium,
cobalt,copper,iron,lead,manganese,mercury,molybdenum,nickel,thallium,uranium,
vanadium,and zinc.The average concentration of natural uranium was calculated to be
94 mg/I.
2.2 SITE CHARACTERISTICS
2.2.1 Climate
The elimate ofthe Blanding area is considercd semi-arid with normal annual precipitation
of 13.3 inches (Utah Climate Center,2007).Most precipitation falls in the form of rain,
with about one-qumter of the precipitation falling as snow.There are two separate
rainfall seasons in the area:a late summer season when monsoonal moisture from the
Gulf of Mexico leads to thunderstorms and a winter season related to fronts from the
Pacific.The average annual Class A pan evaporation rate is 68 inches.
Climatological data are available for the weather station near Blanding,Utah (420738),
located approximately six miles north ofthe White Mesa Mill at an elevation of 6,040 ft
above mean sea level (amsl).Data are available for the period December 1904 through
2-8
December 2006;however,large gaps in the dataset (i.e.,missing precipitation and/or air-
temperature measurements)occurrcd during 1905,1910 to 1912,1915,1916, 1917,1927,
1929,1931,1989,and 2005.Data for the period bctween 1932 and 1988 are nearly
continuous.
The long-tcnn avcrage annual precipitation at the Blanding weather station was
13.3 inches with a standard deviation of 3.9 inches.Annual precipitation for the period
1905 through 2005 is presented in Figure 2-3.The largest annual event occurred in 1909
(24.5 inches),but other years that exceeded 20 inches inelude 1906 (23.6 inches),1957
(22.4 inches),1941 (21.5 inches),1908 (20.2 inches),1997 (20.2 inches),and 1965
(20.1 inches).Daily precipitation for the period 1905 through 2005 is presented in
Figure 2-4.The largest daily precipitation event was 4.48 inches,which occurred on
1 August 1968.
The mean annual temperature for Blanding,Utah is 52°F,based on the period 1971-2000.
January is typically the coldest month, with a mcan monthly temperature of about 30°F.
July is generally the warmest month, with a mean monthly temperature of 76°F.Daily
ranges in temperatures are typically large.
Winds are generally light to moderate (less than 15 miles per hour)at the site during all
scasons,with winds prevailing from the south.Strong winds are associated with summer
thunderstorms and frontal activity during the late winter and spring.
2.2.2 Summary of Site Geology
The White Mesa Mill is located within the Blanding Basin of the Colorado Plateau
physiographic province.The average elevation at the site is 5,600 ft ams!.The site is
underlain by unconsolidated alluvium overlying consolidated sedimentary rocks
consisting primarily of sandstone and shale.The unconsolidated deposits are primmily
aeolian silt and sand and range from 1 to 30 ft thick (these deposits have been removed
where the tailings cells are located).The consolidated bedrock underlying the site is
relatively undeformcd and horizontal (gencrally dips are less than 3 degrees).The first
units cncountered are the Crctaceous-aged Dakota Sandstone and Burro Canyon
2-9
Formation,both sandstone units having a combined thickness of 100 to 140 ft beneath the
site.Beneath the Burro Canyon Formation is the Morrison Formation,which is primarily
shale.The Brushy Basin Member is the uppcnnost member ofthe Morrison Formation
and is composed primarily of bentonitic mudstones,siltstones,and claystones.The
contact between the Burro Canyon Formation and Brushy Basin Member dips gently to
the south.Beneath the Brushy Basin Member are the Westwater Canyon,Recapture,and
Salt Wash members of the Morrison Formation.Beneath the Morrison Formation are the
Summerville Formation,Entrada Sandstone,and Navajo Sandstone.For more detailed
descriptions of the geologie setting see the Reclamation Plan,Revision 3.0 (International
Uranium (USA)Corporation,2000).
.2.2.3 Site Hydrogeology
Groundwater beneath the site is first encountered as a perched zone within the Burro
Canyon Formation.The low permeability Brushy Basin Member acts as an aquitard and
fonns the base of the perched aquifer.Monitoring wells at the site are screened across
the saturated portion of the Burro Canyon Formation and generally extend down to the
contact with the Brushy Basin Member.The saturated thickness of the perched zone
ranges from less than 5 to 82 ft beneath the site,assuming the base ofthe Burro Canyon
Formation is the base of the perched aquifer.The water table of the perched aquifer was
encountered at 13 to I 16ft below ground surface (bgs)at the facility in 2007 (57 to
I 16ft bgs beneath Cells 2,3,and 4A).The perched water table is shallowest near the
wildlife ponds (13 ft in piezometer P-2),east of the Mill and tailings cells.Groundwater
within the perched zone generally flows south to southwest beneath the site (see
Figure 2-5).Recharge to the perched aquifer is primarily from areal recharge due to
infiltration ofprecipitation and seepage from the wildlife ponds on the eastem margin of
the site.Discharge from the perched aquifer is believed to be to spriugs and seeps along
Westwater Creek Canyon and Cottonwood Wash to the west-southwest and along Corral
Canyon to the east ofthe site.The discharge point located most directly downgradient of
the tailings cells is believed to be Ruin Spring in Westwater Creek Canyon,a tributary to
Cottonwood Wash,approximately two miles from the tailings cells.
2-10
The horizontal hydraulic gradient in the perched aquifer ranges from approximately
0.01 to 0.04 feet per foot (ftlft)and is generally to the south and southwest with local
variations in magnitude and direction (see Fi6>1.1re 2-5).Recharge from the wildlife ponds
causes localized mounding ofthe water table.
The hydraulic conductivity of the perched aquifcr has been characterized through aquifer
pumping tests,slug tests,packer tests,and laboratory analysis of core samples.The
results of aquifer pumping tests perfonned in 12 monitoring wells and packer tests
performed in 30 borings in the perched aquifer are presented in the Reclamation Plan,
Revision 3.0 (International Uranium (USA)Corporation,2000).The geometric mean
horizontal hydraulic conductivity of the perched aquifer is 0.03 ft/day (1.0 x 10-5
centimeters per second [em/secJ),based on the average of values estimated from 12
aquifer pumping tests and from 30 packer tests.The horizontal hydraulic conductivity
from these tests ranged from 5.4 x 10.4 to 4.5 ft/day (1.9 x 10-7 to 1.6 X 10.3 em/sec)
(TITAN Environmental Corporation,1994).
Additional hydraulic testing was perfonned in 2002,which focused on wells to the south
of Cell 3.In this effOli,one monitoring well was pump tested and seven monitoring
wells were slug tcstcd,the results of which are presented in Hydraulic Testing at the
White Mesa Uranium Mill near JJlanding,Utah during July 2002 (Hydro Geo Chem,
Inc.,2002).Hydraulic conductivity values from these tests ranged from 0.0022 to
1.5 ft/day (7.7 x 10.7 to 5.3 X lOA cm/see).The geometric mean hydraulic conductivity
for wells south of Cell 3 (MW-3,MW-5,MW-ll,MW-12,MW-14,MW-15,MW-17,
MW-20,and MW-22)ranged from 0.054 to 0.12 ft/day (1.9 x 10-5 to 4.1 X 10.5 em/see),
depending on the slug test analysis method used (Hydro Geo Chcm,Inc.,2003).
Using the geometric mean values for horizontal hydraulic conductivity,horizontal
hydraulic gradient,and assuming a porosity of 18.3 percent (the average from samples
collected while drilling MW-16,which also corresponds closely with the average of
values from cores analyzed from MW-23 and MW-30 discussed below in Section 2.2.5),
the average linear velocity of groundwater is estimated to be 0.002 ft/day.Using
hydraulie properties for the perched zone downgradient of the tailings cells,average
2-11
linear velocities of groundwater were calculated to range from 0.0035 to 0.0076 ft/day
(Hydro Geo Chem,Inc.,2003).For finiher details concerning hydrogeology see Site
Hydrogeology and Estimation ojGroundwater Travel TImes in the Perched Zone,White
Mesa Uranium Mill Site,near Blanding,Utah (Hydro Geo Chem,Inc.,2003),Hydraulic
Testing at the White Mesa Uranium Mill Site,near Blanding,Utah During July 2002
(Hydro Geo Chem,Inc.,2002),Hydrogeological Evaluation oj White Mesa Uranium
Mill (TITAN Environmental Corporation,1994),and the Reclamation Plan,Revision 3.0
(International Uranium (USA)Corporation,2000).
2.2.4 Groundwater Quality
The groundwater quality of the perched aquifer is highly variable with TDS
concentrations that range from 600 to over 5,300 mgll.Based on historical data from
33 wells,16 appear to have Class II or drinking water quality groundwater and the other
17 have Class III or limited use quality groundwater.Manganese,selenium,and uranium
have been found to exceed their respective State Ground Water Quality Standards at
several monitoring wells.
Average chloride concentrations in the perched groundwater south of Cell 4A for the
period 2006-2007 ranged from 18 to 63 mgll.Chloride concentrations in monitoring
wells MW-14 and MW-15 located along the south side of Cell 4A had average
concentrations for 2006-2007 of 18 and 39 mgll,respectively.Average sulfate
concentrations in the perched groundwater south of Cell 4A for the period 2006-2007
ranged from 2,180 to 3,320 mgll.Sulfate eoneentrations in monitoring wells MW-14 and
MW-15 had average eoncentrations for 2006-2007 of2,180 and 2,380 mgll,respectively.
Average uranium concentrations in the perched groundwater south of Cell 4A for the
period 2006-2007 ranged from 28.9 to 59.8 mierograms per liter ('lgll).Uranium
eoncentrations in monitoring wells MW-14 and MW-15 had average eoneentrations for
2006-2007 of 59.8 and 49.3 J.lglI,respectively.
For additional detail regarding groundwater quality see the Revised Background
Groundwater Quality Report (lNTERA,2007).
2-12
2.2.5 Vadose Zone Characteristics
The vadose zone beneath White Mesa is the zone between the gronnd surface and the
perched water table.The vadose zone is within the unconsolidated deposits (removed
during construction of the tailings cells),the Dakota Sandstone,and Burro Canyon
Formation.The vadose zone is 13 to 116 ft thick,based on the depth to groundwater in
2007 (between 57 and 116 ft thick based on water levels in monitoring wells in the
vicinity ofCells 2,3,and 4A).
Although no site specific data are available,water contents in the vadose zone are
believed to be very low due to the semi-arid cnvironment.Water contents beneath the
wildlife ponds are likcly to be high due to artificial recharge caused by pond leakage.
Select core samples eollccted while drilling monitoring wclls MW-23 and MW-30 were
analyzed for unsaturated hydraulic properties by the laboratory at Daniel B.Stephens &
Associates (2007).These samples are from the Dakota Sandstone and Burro Canyon
Formation and were selected by MWH to reprcscnt the vadose zone beneath the tailings
cells.Samples were analyzed for porosity,saturated hydraulic conductivity,and
unsaturated soil water retention propeliies.Vutieal hydraulic conductivity values .were
determined for the cores with falling head tests performed with flexible wall
pcrmcameter.Soil-water rctention values wcre detcrmined with a combination of
hanging columns (0 to -200 em pressure),pressure plates (-500 em pressure),water
activity meters (-15,000 to -44,000 em pressure),and rclative humidity box (-851,000 em
pressure).From these data,van Gcnuchten parameters (see Scetion 2.3)were estimated
for soil water rctention curves and unsaturated hydraulic conductivities.Hydraulie
properties detennined with these tests are summarized in Table 2-1;for complete results
including graphical representations of the soil-water retention curves and unsaturated
hydraulic conduetivity functions,see Appendix A.Saturated veliieal hydraulie
conduetivities ranged from 2.9 x 10-5 to 3.0 X 10-3 ern/sec with a geometric mean of2.7 x
10-4 em/sec for the samples analyzed.Generally,unsaturated hydraulic conductivity
decreases dramatically as moisture contents decline.Under relatively dry conditions,the
unsaturated hydraulic conductivity of sand is lower than that of silt and clay for a given
2-13
soil-water pressure (pressure is negative and commonly referred to as tension).This is
because the volumetric water content of a sand under relatively dry conditions is lower
than that ofsilt and clay for a given soil-water pressure.
The vertical hydraulic conductivity of the underlying Brushy Basin Member is
significantly lower demonstrating why it acts as a perching layer.Cores from the Brushy
Basin Member had vertical hydraulic conductivities of 7.28 x 10-11 to 5.95 X 10-4 em/sec
with a geometric mean of 1.23 x 10-8 em/sec (International Uranium (USA)Corporation,
2000).
2.3 VADOSE ZONE FLOW AND TRANSPORT CONCEPTUAL MODEL
This section presents the conceptual model for flow and potential contaminant transport
in the vadose zone.Details of the implementation of the conceptual model into the
numerical model as well as parameter values,boundary conditions,and initial conditions
used in the modeling are described in detail in Section 3.0.
2.3.1 Unsaturated Flow
Unsaturated Flow Governing Equation.Unsaturated flow through the vadose zone can
be described with a modified Richards'Equation.The Richards'equation is derived by
combining the Darcy-Buckingham equation with the mass continuity equation.For one-
dimensional vertical flow the governing flow equation is given by the following modified
form ofthe Richards'equation (Simunek et a!.,2005):
oe =iJ_[K(oh +1)]-3otOZOZ
where:
e volumetric water content [L3L·3]
h water pressure head [L]
2-14
S sink term =volume of water removed from a unit volume of soil per
unit time (e.g.,uptake by plants)[L3L-3r l]
z spatial coordinate in the vertical direction [L]
t =time [T]
K unsaturated hydraulic conductivity [Lrl].
The unsaturated hydraulic conductivity is a function of the volumetric water contcnt and
pressure hcad and as a result can vary in both space and time.
Unsaturated Hydraulic Conductivity.To solve the above equations;it is necessary to
specify tbe relationships of unsaturated hydraulic conductivity versus water saturation
(Sw),and of pressure head (h)versus water saturation (0).Tbe relationship of pressure
head (b)to water saturation (0)is described by the following equation (van Genuchten,
1980;Mualum,1976).
h<O
h?cO
where:
0,=the residual water content [L3L'3]
Os =tbc saturated water content [L3L·3]
h =tbe pressure head [L]
a =the inverse ofthe air-entry value (or bubbling pressure)[L·I ]
n =the pore size distribution index [dimensionless]
m=I-l/n ,n>1
2-15
The relationship of unsaturated hydraulie eonduetivity versus water saturation IS
deseribed by the following equation (van Genuehten,1980):
K(h)=K,S;[I-(1-S;t"'rj
where:
K(h,z)=
Ks =
L
m =
unsaturated hydraulic eonduetivity funetion [LTI ]
saturated hydraulic conductivity [LT1]
the effective saturation [dimensionless fraction].
the pore connectivity parameter [dimensionless]
I -1/n,where n>I
For unsaturated porous media,the pressure head of soil porewater is negative (i.e.,less
than atmospheric pressure)and is eommonly referred to as matric potential or soil-water
tension (negative).The unsaturated hydraulie conductivity is a function of the saturated
hydraulic conductivity,pressure head,and moisture content.As a result,the unsaturated
hydraulic conductivity in the vadose zone can vary through time.See Table 2-1 for
properties Ks,a,n,0"and Os from the six cores tested as described in Section 2.2.5.
Plant-Water Uptake.The sink term in the Richards'Equation is defined as the volume
ofwater removed from a unit volume of soil per unit time.This accounts for plant-water
uptake and can he defined in terms of soil-water pressure head as described by the
following equation (Feddes et aI.,1978):
S(h)=a(h)Sp
where:
a(h)-root water uptake water stress response function [dimensionless]
potential water uptake rate [T1]
2-16
The value of a(h)ranges between 0 and 1.Below a certain head,when conditions are
extremely dry,plants cease to uptake water.A plant-root-distribution function can also
be used to account for variable plant-water uptake with depth.For grasses,roots are
usually most dense near the ground surface and decrease with depth (Kurc and Small,
2003;Foxx and Tierney,1987;Schuster,1964;Lee and Lauenroth,1994).
2.3.2 Contaminant Transport in the Unsaturated Zone
Transport through the vadose zone is affected by adveetion,dispersion (both mechanical
dispersion and molecular diffusion),sorption,and degradation or other transfonnations
(e.g.,biotransformations,radioactive decay,precipitation and loss from aqueous
solution/sorption).Advective velocities are largely controlled by soil moisture content
because the unsaturated hydraulic conductivity and effective porosity varies through time
as moisture content varies.
Contaminant Transport Governing Equation.Contaminant transport can be described
by the advection-dispersion equation (ADE).The governing equation for unsaturated
zone contaminant transport with advection,dispersion,sorption (retardation)of
contaminants,as well as production and transformations (losses)of contaminants is
(Simunek et a!.,2005):
where:
i/C acD-~-V ·--=R'a/'az
ac~+RA.C+Rat
z spatial coordinates in the vertical direction [L]
C dissolved concentration ofchemical [ML-3]
D,dispersion coefficient in the z direetion [L2T 1]
Vz one dimensional,uniform seepage velocity in the z direction [LT1]
R retardation factor [dimensionless]
2-17
t ~elapsed time [T]
'Ie .effective first-order decay coefficient [TI]
q net recharge [Crt]
e volumetric water content [L3L'3].
Dispersion.The process of hydrodynamic dispersion acts to dilute and spread
contamination as it is transported by advection.Hydrodynamic dispersion is the
combination of mechanical dispersion and molecular diffusion.Mechanical dispersion is
generally dominant unless flow velocities are extremely slow,as may be the case under
very dry conditions with extremely low unsaturated hydraulic conductivities.There are
three basic factors contributing to mechanical dispersion:
velocity differenccs in an individual pore and between pores of different sizes
transverse diffusion into pores ofstagnant water or slower velocity relative to
faster flow paths
molecular diffusion ahead of the wetting front.
These processes occur in all porous media.Longitudinal dispersion spreads the
contaminant along the direction of flow whereas transverse or lateral dispersion spreads
the contaminant perpendicular to flow.Both have the effect of spreading of
contaminants,and increasing the plume area,while decreasing contaminant
concentrations through dilution.At the field scale,aquifer heterogeneities also will cause
dispersion.Flow perpendicular to layered heterogeneities (as in the vadose zone at White
Mesa where bedding is flat lying)leads to relatively less dispersion than flow parallel to
bedding planes (Khaleel et a!.,2002).
2-18
The hydrodynamic dispersion coefficient in the liquid phase is defined as (Simunek et aI.,
2005):
where:
D =hydrodynamic dispersion coefficient leT']
DL =longitudinal dispersivity [L]
q =Darcian fluid velocity [LT']
e=volumetric water content [L3L-3]
Dw =molecular diffusion cocfficient in free water [L2r']
t w =tortuosity factor in the liquid phase [dimensionless].
Sorption and Retardation.Chemical reactions betwcen dissolved constituents in
groundwater (e.g.,metals and radionuclides)and the aquifer matrix often dictate spatial
and temporal variations in contaminant-plume transport and mobility in the subsurface by
controlling the degree of adsorption-dcsorption of aqucous complexes to surface
assemblages.Surface-complexation models apply principlcs of chemical equilibrium to
reactions between dissolved species and potential sorption sites.A series of
hetcrogeneous mass-action equations,mass-balance equations for surface sites,and
charge-potential relations for each surface are coupled with aqueous-speciation equilibria
to determine sorbate-sorbent interactions,commonly using a geochemical-computer code
(e.g.,Parkhurst and Appelo,1999).In the geochemical model PI-lREEQC,surface-
complexation reactions are reproduced after the Dzombak and Morel (1990)double-layer
model with the option to include effects from electrostatic potentials (Parkhurst and
Appelo,1999).The gcncralized,two-layer model quantifics the adsorption of speciated-
aqueous complcxes onto hydrous-fenic oxide (I-IFQ)surface sites (Dzomliak and Morel,
1990).
2-19
For a specific contaminant that cxhibits linear sorption,a rctardation factor can be
calculated with the distribution cocfficient (Freeze and Cherry,1979):
R =1 +PbKI/e
where:
R
Pb
e
=retardation factor of contaminant [dimensionless]
dry soil bulk density ofthe porous media [ML-J]
sorption coefficient of contaminant [LJM-']
volumetric water content [eL-\
A retardation factor of 1.0 indicates that the contaminant plume migrates at the same rate
as the advective velocity,as is typically the case for chloride.Retardation values used in
the modeling are presented in Section 3.0,and described in detail in Appendix B.
Sorption and retardation values for other site contaminants are presented in Section 4.3
and Table 4-1,and describcd in detail in Appendix B.
2-20
TABLE 2-1
lJNSATlJRATED HYDRAULIC I'ROl'ERTIES FOR CORES FROM WlIlTE MESA
Saturated
Iuverse Pore-Size Residual Saturated Hydraulic
Sample Depth Air-Entry Dsitribution soil water soil water Dry Bulk Conductivity
Location (feet below Pressure a Index 11 content Or content Os Density KS:l1
II)ground surface){em'l)l (dimensionless)'(%vol)CYll vol)!(grams/em)(em/sec)
MW-30 35.5-36.0 00266 1.348 0.00 19.86 1.98 8.11'-04
MW-30 44.0-44.5)0.0074 1202 000 27.59 2.23 8.21'-06
44.0-44.5)
MW-30 volume adjusted 0.0081 1201 0.00 26.43 2.12
MW-23 55.5~56.0 00103 i .386 0.00 18.38 2.03 11'-04
MW-23 74.3-74.6 00003 1.354 0.00 12.16 2.33 2.91'-05
MW-23 82.7-82.9 00069 1336 0.00 16.01 2.10 1.71'-04
MW-23 103.3-]03.5 00287 1.349 000 20.51 1.84 301'-03
Notes:All testing performed by Daniel 13.Stephens &Associates,Inc.Laboratory /Testing Facility.
For full results sec Appendix A.
I.Parameter in van Gcnuchtcn soil water retention function
2.Equivalent to total porosity
3.Sample MW-30 44.0-44.5 experienced swelling and water gain during and aner the initial
saturation process.This sample also cracked horizontally during moisture retention testing
I DETAIL 1 -TAILINGS COVER DESIGNII~,"'if-.r~"I II VEGETATION (PRIMARilY GRASSES)
I ,-~..~.:.-·~I~;TOP-SOIL WITH GRAVEL
I \I...k •~.I \~FROST BARRIERMIATER STORAGE~(SANDYSILTAND SILTY SAND)M
;;\\.S,,\J'!
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TAILINGS
;;
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I DETAIL 2 -TAILINGS CELL LINER SYSTEMI
I
I Cells 2 and 3I
I \'\''\":\'\',\SLIMES DRAIN COLLECTION SYSTEMfLEAN SANDI\\\",,\\\\\\\,'\,1FT WITH PERFORATED PVCPIPE;IN L1MI EDAREA$ONLY)I
I 1FT LINERPROTECTIVE BLANKET (NATIVE SILTY·SAND SOIL)I
\,,'\\\\\\\\05 FT 30 ML pvc FLEXIBLE MEMBRANE LINER,MO"UNDERLAY(CRUSHED SANDSTONE)
Cells 4A and 48
\\,,\''0.\\,\\\SLIMES DRAINS\60 MILHOPE GEOMEMBRANE
DAKOTA \GEQNET DRAINAGE SYSTEM(PRIMARILY LEAK DETECTION)
\60 MILHOPE GEOMEMBRANESANDSTONE\11111111 11111111111111111111111 III GEOSYNTHETIC ClJ\Y LINER (Gel)
\\\,\\\',0.5 FT\,.\\,\\,(MIN)UNDERlAY(CRUSHED SANDSTONE)
\
\
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0
BURRO CANYON DENISON MINES (USA)CORP.
FORMATION Y WATER TABLE
WHITE MESA MILL
GENERALIZED CROSS SECTION
Note:Closs section represents minimum separation distance between WITH MODIFIED COVER DESIGN
tailings and watertable based on data from monitoring wells.
FIGURE 2-2
FILE Fig 2-3 Denison Annual.orecip_CharL807.ai 08/30107 SLC
25
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o 11111111111111111 111111111111111
1905 1915 1925 1935 1945 1955
Year
1965 1975 1985 1995 2005
Note:years with incomplete data not shown.
DENISON MINES (USA)CORP,
WHITE MESA MILL
ANNUAL PRECIPITATION AT BLANDING,UTAH
(1905 TO 2005)
FIGURE 2-3
FILE Fig 2-4 Denison Dailyprecip_Chart_807.ai 08130107 SLC
5
4.5
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200519951985197519651955
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1945193519251915
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DENISON MINES (USA)CORP.
WHITE MESA MILL
DAILY PRECIPITATION AT BLANDING,UTAH
(1905 TO 2005)
FIGURE 2-4
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Big Bench,Utah Quadrangles.
Coordinates are UTM Zone 12.
NAD 1927 meters.
EXPLANATION
-$-Monitoring well
V Piezometer
DENISON MINES (USA)CORP.
WHITE MESA MILL
SITE MAP
FIGURE 2-1
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EXPLANATIONNW+E
So 2000
FUI
Note:Water level contours from
Hydro Geo Chern.Inc.(2003)
Wells MW-23 to MW-32.
Base mapadapted from USGS 7.5 Minute
Topographic maps ofBlack Mesa Butte,
B/anding South,No-Mans Island,
andBig Bench,Utah Quadrangles.
Coordinates are UTMZone 12,
NAD 1927 meters.
-
~
V
Water level contour line,
dashed where uncertain
Monitoring well
Piezometer
DENISON MINES (USA)CORP.
WHITE MESA MILL
PIEZOMETRIC SURFACE CONTOURS
PERCHED AQUIFER
(SEPTEMBER 2002)
FIGURE 2·5
3.0 METHODOLOGY
3.1 OVERALL MODELING APPROACH
This section provides information regarding the conceptual and mathematical models
used in:
Predicting potential infiltration rates through the tailings cell cover;
Predicting potential flow and contaminant transport ji-om the tailings (Cells 2,
3,4A,and 4B)through the tailings cell liner system and underlying vadose
zone to the water table;and
Predicting potential contaminant transport Il1 the perched aquifer and
subsequent impacts to groundwater quality.
Following conceptual-model development,numerical modeling was completed
sequentially according to the numbered list detailed below (see Figure 3-1):
1.Vadose zone now modeling with HYDRUS-ID of the tailings cell cover with
daily precipitation and evapotranspiration to estimate potential infiltration
rates to the tailings.
2.Groundwater now modeling with MODFLOW of Cells 2 and 3 to estimate
tailings-dewatering rates through time and average water levels (saturated
thickness)that wil1 remain in the tailings (water-yield properties of tailings
predicted with HYDRUS-ID in step 1 above).The predicted saturated
thickness of the tailings after active dewatering is used as an initial condition
in the l-lYDRUS-l D model ofthe tailings and vadose zone in steps 3,4 and 5
below for Cells 2 and 3 (dewatering predietions for Cells 4A and 4B were
fj-om Geosyntee Consultants [2007bD.
3.Vadose zone now modeling with I-IYDRUS-ID of tailings to get initial
conditions for moisture content and pressure head in tailings above the
3-1
saturated laycr (potential inliltration through cover predicted by I-IYDRUS-I D
in step I;saturatcd thiekncss oftailings prcdicted with MODFLOW in step 2).
4.Vadose zone flow modeling with HYDRUS-ID of tailings,tailings cell liner
system,and underlying vadose zone to calibrate for lincr properties and obtain
quasi-stcady-state water content and pressure head throughout the vadose
zone (potential infiltration rate through the cover from HYDRUS-ID
modeling in step I;saturated thickness of tailings predicted with MODFLOW
in step 2;initial water contents and pressure head in tailings above saturated
tailings fi-om HYDRUS-]D in step 3).
5.Vadose zone flow and potential contaminant transport modeling with
I-IYDRUS-I D of tailings,tailings cell liner system,and underlying vadose
zone (potential intlltration rate through the cover from ]-IYDRUS-ID
modeling in stcp I;initial saturated thickness hom MODFLOW modeling in
step 2;initial water contcnt and pressure head in tailings above saturated
tailings fi-OlD HYDRUS-I D in step 3;initial water content and pressurc head
in vadose zone from HYDRUS-ID in step 4).
6.Groundwater flow and potential contaminant transport modeling of perched
aquifcr simulated with MODFLOW and MT3DMS (potential contaminant-
source loading,contaminant concentrations,and groundwater-recharge rates
beneath the tailings cells predicted with l-IYDRUS-ID modeling in step 5).
Detailed descriptions ofthe modeling eHclrt arc provided in the remainder ofthis section.
Vadose-zone modeling is described in Section 3.2;groundwater modeling of the tailings
cell dewatering,in addition to groundwater flow and potential contaminant transport in
the perched aquifer,is described in Section 3.3.For ease of comparison to model files,
wherever possible,units of measure used in the models have been retained in the text
(i.e.,feet and days for MODFLOW,ccntimeters and days for HYDRUS-!D,and mgll for
both MT3DMS and HYDRUS-lD).
3-2
3.2 VADOSE ZONE FLOW AND TRANSPORT MODEL
3.2.1 Computer Code
The computer code HYDRUS-I D was used for the infiltration and contaminant transport
modeling.HYDRUS is a finite-clement model that simulates water flow and solute
transport in variably-saturated media,and was dcveloped by the U.S.Salinity Laboratory
in collaboration with the Department of Environmental Sciences at thc University of
California at Riverside (Simunek et aI.,1998;Simunek et aI.,2005).The program can be
used to analyze water and solute movement in unsaturatcd,partially-saturated,or
saturated porous media.I-IYDRUS allows for spatial and temporal variation in soil
properties,allowing for simulation of a heterogeneous soil proftie under variably-
saturated,unsteady-flow conditions.I-IYDRUS can simulate one-dimensional advection,
dispersion,retardation (sorption),and degradation of contaminants.HYDRUS was
selected because it is capable of simulating the dominant processes affecting infiltration
and contaminant transport given the semi-arid conditions and multiple layers (cover
layer,tailings,and vadose zone)that must be simulated at the site.
HYDRUS-ID is one of the few,commercially available,frequently tested models that
ean simulate both unsaturated flow and contaminant transport in the vadose zone
(including layered stratigraphy)with a variety of initial and boundary conditions.
Consideration of discontinuities in capillary and unsaturated hydraulic conductivity is
very imp0l1ant for layered systems because travel times and storage of water and
contaminants in the vadose zone is complex (due to potential capillary-barrier effects).
The modcl provides accurate results when appropriate spatial discretization for the finite-
element domain is established.
I-IYDRUS has been used to simulate deep percolation beneath final-closure designs for
radioactive-waste management at the Nevada Test Site,flow around nuclear-subsidence
craters at the Nevada Test Site,and influences of a capillary barrier at the Texas low-
level radioactive waste disposal site.A comparison of HYDRUS to other codes
(CHAIN,MULTIMED-DP,FECTUZ,and CHAIN 2D)was prepared by the
U.S.Environmental Protection Agency in order to evaluate each code's ability to predict
3-3
radionuclide fate and transport in the unsaturated zone (Chen et aI.,2(02).Of the codes
evaluated by Chen et al.(2002),HYDRUS was the most comprehensive,containing the
greatest number of physical processes.Scanlon et al.(2002)performed a comparison of
codes for simulation of landfill covers in semi-arid environments.fn addition to
HYDRUS,the evaluation by Scanlon et al.(2002)included the codes HELP,Soil-Cover,
SHAW,SWIM,UNSAT-H,and VS2DTI.This evaluation indicated that Riehards'-
Equation-based codes such as I-IYDRUS-I D are more appropriate for simulating near
surface water balance than those using a water-balance approach such as HELP.Only
HYDRUS-I D,SWIM,and VS2DT1 could simulate a seepage face.Of these VS2DTI,
did not simulate the upper atmospheric boundary conditions as well as HYDRUS-ID.
The HYDRUS-ID program numerically solves the Richards'equation for
saturated/unsaturated water flow and the Fiekian-based advection-dispersion equation for
heat-and-solute transport.I-IYDRUS-I D incorporates unsaturated soil-hydraulie
properties using the van Genuehten (1980),Brooks and Corey (1964),or modified van
Genuchten-type (Vogel and Cislerova,1988)analytical functions.The water llow
pOliion of the model can incorporate (constant or time-varying)prescribed head and flux
boundaries,as well as boundaries controlled by atmospheric conditions.Soil surface
boundary conditions may change during the simulation fi·om prescribed flux to prescribed
head-type conditions.The code also allows f(lr internal sinks such as plant-water uptake.
The I-IYDRUS-ID program numerically solves the adveetive-dispersive equation for
solute transport.The transport equations include provisions for nonlinear and/or
nonequilibrium reactions betwecn the solid and liquid phases,linear equilibrium
reactions betwecn the liquid and gaseous phases,zero-order production,and two first-
order degradation reactions (one indepcndent of other solutcs and one which provides
coupling between solutes involved in sequential first-order decay reactions).The code
supports both (constant and time-varying)prescribed concentration and concentration
flux boundaries.The dispersion tensor includes a term relleeting the effects of molecular
diffusion and tortuosity.
3-4
3.2.2 Domain
The vadose-zone-model domain consisted of a one-dimensional conceptual
rcprcsentation of the planned cover design,tailings,liner system,and underlying site
stratigraphy.That is,the model domain is a one-dimensional vertical column extending
ti'om the land surface at the top surface of the tailings ccll cover to the perched water
table in the Burro Canyon Formation (see Figure 3-1).The vadose zone beneath Cells 2
and 3 was assumed to be 42-tt thick,representing the minimum distance ti'OI11 the base of
the tailings to the perched water table,based on the average 2007 water level in
monitoring well MW-30 and the base of Cell 3.The vadose zone beneath Cells 4A and
413 was assumed to be 40-ft thick,representing the minimum distance Ii'om the base of
the tailings to the perched water table,based on the average 2007 water level in
monitoring well MW-25 and the base ofCell4A.The top of the domain corresponds to
the top of the tailings cell cover layer.The base of the domain corresponds to the
perched water table in the Burro Canyon Formation.To reduce simulation times,the
domain was subdivided into two sub-domains tor the diilerent modeling steps as
described in Section 3.1 above.As illustrated in Figure 3-1,the tirst sub-domain
represented the cover system only (simulated in step I),while the second sub-domain
represented the tailings,tailings cell liner system,and underlying vadose zone (simulated
in steps 3-5).Furthermore,there were two separate models of the second sub-domain
representing the tailings,tailings cell liner system,and underlying bedrock vadose zone:
one model representing Cells 2 and 3 and a second model representing Cells 4A and 413.
3.2.3 Finite Element Node Spacing
The finite-element nodes were diseretized in the vertical direction to simulate layers in
the tailings cell cover,tailings,tailings cell liner system,and vadose zone.Construction
of the tinite-clement mesh is dependent on surface and bottom boundary conditions and
represented lithologic heterogeneities due to stratigraphic layering (Simunek et a!.,2005).
As a result,node spacing was finer than the geologic layers and tailings-cover layers in
order to simulate steep hydraulic gradients whieh result tiOl11 transient wetting
(precipitation and intiltration)and drying (evapotranspiration)tionts.Fine-grid spacing
3-5
IS necessary to accurately simulate water tlow through the unsaturated zone since
hydraulic properiies vary significantly as a function of moisture content and pressure
head.Because hydraulic properties vary much faster and on a tiner scale ncar the land
surtilee due to rapid changes in atmospheric conditions (daily variations in precipitation
and evapotranspiration were modeled),the node spacing varied between 0.1 and 1 em
near the top ofthe domain representing the tailings-cover system.Whereas deeper in the
vadose zone (i.e.,in the Dakota Sandstone),the node spacing varied between I and
J0 em since moisture contents and pressure heads (i.e.,hydraulic properties)vary at a
much slower rate.Due to the extremely low hydraulic conductivity in the tailings cell
liner system,the node spacing varied between 0.5 and I em.In order to reduce errors due
to numerical dispersion,the ratio between neighboring elements did not exceed 1.5
(Simunek et aI.,2005).
3.2.4 Boundary Conditions for the Vadosc Zonc Flow Model
As discussed above,the domain was subdivided to per!llrll1 simulations t(lr difTerent
purposes;as a result,additional intermediate boundary conditions were required for each
separate sub-domain.For the fist sub-domain,an atmospheric upper boundary condition
was applied across the top of the model representing the tailings cell eovcr to simulate
meteorological conditions and was a tunction of precipitation and potential
evapotranspiration,as described in the paragraphs that follow.Free drainage (i.e.,unit
gradient)was assumed for the lower boundary condition of the model representing the
tailings cell cover,which is conservative in that it probably overestimated potential How
ti'om the base of the cover.For the second sub-domain,which simulated potcntial How
and transport hom the tailings through the vadose zone to the water table,specified
Huxes werc applied to the upper boundary at the top of the tailings.Values for these
specified fluxes were determined using the results from the tailings cell cover model.
The lowcr boundary at the base of the domain was assumed to he fully saturated (i.e.,
water table conditions with a constant pressure head equal to atmospherie pressure),
representing the water-table surface of the perched aquiter.Because of the onc-
dimensional nature of the model,the sides of the domain arc implicitly assumed to be
zero-Hux boundaries.
3-6
Atmospheric Bonndary Condition.Daily precipitation and air-temperature
measurements were obtained for the Blanding weather station and used in the model
(Utah Climate Center,2007).Given the flat nature of the cover (0.2 percent slope),no
runon-or runot1:based processes wcre assumcd to occur and a surfilce layer with a
maximum pressure head of zero was defined for the upper boundary condition applied
across the top of the model.As a result,precipitation applied to the upper boundary was
either removed through evaporation or transpiration,retained in thc soil profile as
storage,or transmitted downward as infiltration (potential recharge to the tailings).The
57-year period between 1932 and 1988 was selected for use in the vadose zone model
because it contained:
a nearly continuous time series
a mixture ofthe largest annual and daily precipitation events
consecutive-wet years.
The third and fourth wettest years on record (1957 and 1941;22.4 and 21.5 inches,
respectively)arc within the time series selected,and are approximately 9%and 14%less
than the maximum annual precipitation of 24.5 inches recorded during 1909.The largest
daily precipitation event of4.48 inches,which occurred on I August 1968,is represented
in the time series selected.
Some interpolation was necessary to construct a continuous time series between 1932 and
1988.Missing precipitation mcasurcments were left blank but accounted for only a small
subset of the population (l0 days out of 20,820 days).Air-temperature measurements
were interpolated between missing data points,but overall accounted for a small subset
(55 days out of20,820 days)ofthe time series.
A combination temperature-based and solar-radiation-based approach was used to
estimate daily evapotranspirative fluxes.Potential evapotranspiration (PET)was
calculated f(ll'each day fi'Oln measured maximum and minimum air temperatures in
addition to estimated radiative fluxes following the methodology outlined in the work of
Allen et al.(1998).The average annual PET between 1932 and 1988 was 47.9 inches.
3-7
Sincc actual evapotranspirative fluxes are a function of atmospheric,hydrogeologic,and
ecologic conditions,PET was partitioned into potential soil evaporation (PE)and
potential transpiration (PT)components.lIYDRUS then calculates transpiration and
evaporation depending on soil-water contents (e.g.,saturation status)and water-stress
properties intrinsic to the prescribed vegetation type.The minimum pressure head
allowed at the surface was fixed at -15,000 cm,which controls how evapotranspiration is
computed (1.Simunek,electronic communication,2006).The fraction of radiation
intercepted by the canopy and transmitted to the soil surface (Campbell and Norman,
1998)was used to partition PET bctween PE and PT assuming a grassland-cover leat~
area-index cqual to 1.2 (Dwyer,2003)and a canopy-extinction coe!llcient equal to 0.67
(Campbell and Non11an 1998).As a result,the fraction of radiation intercepted by the
canopy equaled 55%.
The 57-year climate record comprised of measured precipitation and calculated potential
evaporation and transpiration was repeated to establish a synthetic atmospheric record for
grcater durations (e.g.,200 ycars).Generation of a concatenated atmospheric record
assumes that historic meteorological conditions arc considercd representative tor the
future.
Plant-Water Uptake.The maximum rooting depth was specified as 100 cm based on
average rooting depths reported (or grasses (Kurc and Small,2004;Currie and Hammer,
1979;Foxx and Tierney,1987;Schuster,1964;Lee and Lauenroth,1994).For grasses,
roots are usually denser near the ground surface and decrease with depth.A linear
decrease with depth was assumed tor the root-water-uptake function (i.e.,assumes
vegetation removes more water near the ground surface and less with depth).The root-
water-uptake function is a dimensionless number proportional to the root distribution or
root density.The Feddes et al.(1978)water-uptake model with water-response functions
lor grass was selected in HYDRUS.
3.2.5 Input Parameters for the Vadose Zone Flow Model
Hydraulic properties required tor the vadose zone flow model include vertical saturated
and unsaturatcd hydraulic conductivity,residual soil-water content,saturated soil-water
3-8
content (porosity),and the soil-water-retention curve-fitting parameters.Wherever
possible,site-specific data obtained from previous investigations at the site were used to
construct the vadose zone flow modcl.As presented in Table 2-1 and Appendix A,the
saturated and unsaturated hydraulic properties were measured for cores from the Dakota
Sandstone and Burro Cailyon Formation.Unsaturated hydraulic properties for the
tailings cell cover materials,as well as for the tailings,were estimated using grain-size
data for these materials and the soil-properties database in HYDRUS.Hydraulic
properties used in the model arc presented in Table 3-1.The van Genuehten-Mualem
single-porosity soil-hydraulic-property modcl enabling an air-cntry value of -2 em was
selected to characterize thc soil-hydraulic properties.Lacking site-specific
measurements,the vadose zone was assumed to be unaffected by hysteresis.
During initial transicnt vadose zonc flow simulations without a tailings cell lincr,the
tailings were observed to completely desaturate within an unrealistic timeframe.As a
result,the geomembrane liner was represented as a low-permeability layer in HYDRUS
to more accurately simulate potential water flux and contaminant transport into the
underlying vadose zone.Theoretically,a geomembrane liner should consist of an
impermeable material that precludes leakage into the underlying vadose zone.However,
the occurrence of a limited number ofmanufacturing and installation defects is generally
anticipated and incorporated during asscssment of environmental impacts (Giroud and
Bonaparte,1989).The saturated hydraulic conductivity of the liner was selected as a
fitting parameter,and was calibrated to match potential flux rates predietcd by Knight-
Piesold (1998),assuming 122 em (4 ft)of head above the liner of Cell 3.Using a
combination of empirical and analytical equations,and assuming a certain number of
defects and defect sizes taken from the literature (Giroud and Bonaparte,1989),Knight-
Piesold (1989)calculated a total potential flux rate of 4.6 x 10.4 em/day for Cell 3.This
nux rate was selected as a calibration target for the potential nux through the
geomembrane for Cells 2 and 3.
The saturated hydraulic conductivity of the liner for Cells 4A and 4B was calibrated to a
potential flux rate calculated fc)lIowing the approach outlined in the work of Foose et al.
(200 I),which is very similar to the approach adapted by Knight-Piesold (1989).For
-~--_.~~~~-
3-9
Cells 4A and 413,the j()llowing assumptions were incorporated into the calculations:
30 cm (1 fl)of hcad above the liner (Geosyntec Consultants,2007b),a GCL saturated
hydraulic conductivity of2.4 x lO-2 cm/day (Kashir and Yanful,2001;Jo et aI.,2005),a
GCL thickness of I cm,I-hole defect per acre and 2-scam-tcar dcfects per acre (Giroud
and Bonaparte,1989),a hole radius of 1 mm and a seam-tear width of I cm,and good
contact between the geomembrane and the GCL.The calculated potential nux rate and
calibration target for Cells 4A and 413 was 2.6 x lOA cm/day.
The saturated tailings were allowed to drain and the saturated hydraulic conductivity of
thc geomembrane was varied in order to obtain pseudo-steady-state watcr nuxcs
(equivalent to the seepage velocity calibration target)through the simulated liner.A
saturated hydraulic conductivity of 7.3 x 10-5 cm/day was obtained for the geomembrane
liner in Cells 2 and 3 at a pressure head (i.e.,saturated thickness)of 122 em (4 ft);while a
saturated hydraulic conductivity of 9_2 x Hr5 cm/day was obtained for the geomcmbrane
liner in Cells 4A and 413 at a pressurc head (i.e.,saturated thickness)of 30 cm (1 fl)_
Slight pressurc-head differences above and below the liner between the two scenarios
(calculated vcrsus calibrated)resulted Ii-om equilibration in HYDRUS-ID during tailings
draindown and establishment ofpseudo-steady-state water nuxes.
As a comparison,the calibrated saturated hydraulic conductivities used in the model to
represent the PVC and HDPE liners are approximately three orders of magnitude lower
than a well-eompaeted clay (Geosyntee Consultants,2006)and two orders ofmagnitude
higher than a typical value for a PVC geomembrane and four orders ofmagnitude higher
than a typical value for a HDPE geomembrane reported by Giroud and Bonaparte (1989).
As part ofthe sensitivity analysis,high-and low-variant flux rates through the Cells (and
different saturated hydraulic conductivities of the liners)were simulated to determine a
range ofpotential water fluxes and contaminant transport in the vadose zone.Increasing
the saturated hydraulic conductivity of the liner is equivalent to increasing the number of
presumed defects.
3-10
3.2.6 Initial Conditions for Vadose Zone Flow Model
In the infiltration model,the tailings were assumed to have a saturated thickness of
122 em (4 tt)initially t()J"Cells 2 and 3 and 30 cm (1 tt)for Cells 4A and 4B.The value
tor Cells 2 and 3 is based on the results of the dewatering modeling performed with
MODI'LOW,assuming dewatering will be discontinued after 10 and 14 years,
respectively.The value tor Cells 4A and 4B was calculated with analytical equations
(Geosyntcc Consultants,2007b).The moisture-content protile in the tailings above this
saturated base were ealculated with an assumed steady-state infiltration rate through the
cover,based on the long-term rate determined with the vadose zone tJow model for the
tailings eell eovcr.For all HYDRUS simulations,initial conditions were preseribed as
pressure heads (as opposed to water content)in order to facilitate model convergence.
3.2.7 Boundary Conditions for Vadose Zone Transport Model
For the second sub-domain,which simulated potential tJow and transport from the
tailings through the vadose zone to the water table,specified mass tJuxes equal to zero
were applied to the upper boundary at the top of the tailings.Free drainage was assumed
t()r the lower houndary condition of the model.Because ofthe one-dimensional nature of
the model,the sides ofthe domain are implicitly assumed to be zero-nux boundaries.
3.2.8 Input Parameters for the Vadose Zone Transport Model
Contaminants Modeled.The contaminants modeled were natural uramum,chloride,
and sulhtte.These eompounds are the most dependable indicators of site water quality
and of potential cell failure due to their predominance (uranium)and predominance and
mobility (chloride and su!titte).In particular,beeause sorption of chloride is minimal,it
will migrate unretarded and aet as a conservative tracer and thus would be expected to be
detected before all other site contaminants.Likewise,sulfate will migrate relatively
unretarded and occurs in high concentrations.Uranium was ineluded because it is one of
the primary contaminants of concern and is representative of metals and radionuelides.
Transport of other site contaminants was not explieitly modeled,but rather was inferred
3-11
based on retardation factors calculated f{)r other contaminants relative to chloride,sulfate,
and uranium.
Diffusiou aud Dispersivity.The hydrodynamic-dispersion coefficient for transport in
the unsaturated zone is a function of molecular diffusion and mechanical dispersion.
Molecular-diffusion coefficients filr chloride,sulfate,and uranyl (UO/'J in fi'ee water
assuming infinite dilution werc 1.75,0.92,and 0.37 cm2/day,respectively (Li and
Gregory,1974).The diffusion coefficient for uranyl is considered to be a conservative
estimate since uranium (VI)is expected to complex with dissolved species ineluding
sulfate and carhonatc (Appendix B),which would tcnd to decrease the diffusion
coefficient.Tortuosity,and its effect on molccular dif1'usion,was explicitly modeled
during contaminant transport modeling by incorporation of a tortuosity factor for the
liquid phase (Simunek et aI.,2006).Effective diffusion eocflieicnts for ehforide near
residual saturations are on the order of 0.01 cm2/day (Schacfcr et aI.,1995).Estimates of
dispersivity were assumed equal to 50 em for chloride and sulfate,which is comparable
to values presented in the work of Khaleel et aI.(2002).Given the extremely low
advective velocity ofuranium as a result of sorption,mechanical dispersion was assumed
to be negligible relative to molecular diffusion.Sensitivity of contaminant transport to
variations in dispersivity was also evaluated.
Porosity and Dry-Bulk Density.Porosity and dry-bulk density arc required for the
transport model to calculate advective velocities and retardation betors.Porosity
(saturated-water content)and dry-bulk density of the underlying Dakota Sandstone and
Burro Canyon Formation were measured for core samples collected while drilling
monitoring wells MW-23 and MW-30.Porosity and dry-bulk density values used in the
vadose zone transport model are presented in Table 3-2.
Sorption and Retardation.Retardation rates were calculated based on equilibrium soil-
water partition coefficients (I\.d).Chloride was assumed to migrate unretarded (i.e.,
R =I,no sorption).Similar to chloride,sorption of sulfate is relatively low.Kcl values
for uranium were calculated using the mass of BFO present in the bedrock and the
equilibrated solution compositions predicted with the geochemical code PHREEQC
3-12
(Parkhurst and Appelo,1999).Uranium chcmistry is fitirly complicated and is highly
variahle dcpending on the solution pH,carbonate concentration,and oxidation-reduction
potential of the water.Neutralization of the intlltrating tailings porewaters and sorption
of solutes was determined with PHREEQC.The mass of HFO and calcite was
determined fr)r samples collected fhm1 the vadose zone from the Dakota Sandstone and
Burro Canyon Formation from cores collected while drilling monitoring wells MW-23
and MW -30.For details of the methodology,laboratory-analytical results,and
geochemical-modeling results,refer to Appendix B.K"and resulting retardation factor
values used in the vadose zone transp0l1modei are presented in Table 3-2.
Degradation and Production.No degradation or production of uranium,chloride,or
sulfate was assumed.Radioactive decay of uranium is considered to be relatively minor
due to the slow proccsses involved (e.g.,the half~lifc for natural uranium,which is
predominantly U-238,is 4.4 x 10"years).Although uranium can be removed from
solution through microbial processes,in order to yield more conservative model
predictions these processes were not simulated.
3.2.9 Initial Conditions for Vadose Zone Transport Model
Source Concentrations.Source concentrations for natural uranium,chloride,and
sulfrlte were derivcd from tailings-wastewater samples collected between September
1980 and March 2003 by International Uranium (USA)Corporation and its predecessors
and thc U.S.Nuclear Regulatory Commission as presented in the Statement of Basis
(Utah Division of Radiation Control,2004).For natural uranium,the average
concentration was calculated to be 94 mg/1.For chloride,the average concentration was
calculated to be 4,608 mg/l.For sulfate,the average concentration in the tailings was
64,914 mg/I;however,thc equilibrium concentration was calculated to be 44,248 mg/I,
based on equilibrium with gypsum and barite (sec Appendix B)and was used as the
initial concentration in the vadose zone transport model.For Cells 2 and 3,pore fluids in
the tailings,slime-drain-collection systcm,and liner-protective blanket,wcre assumed to
have these concentrations initially,in which the total amount of mass released in the
protlle is equal to the depth-integral ofthe concentration and volumctrie-water contents at
3-13
time zero.For Cells 4A and 4B,pore-fluids in the tailings and underlying geonet were
assumed to have these concentrations initially.Initially,all water in the tailings was
equal to the average concentrations reported above.No source degradation or treatment
was assumed:the only process reducing thesc conccntrations was flushing with
uncontaminated water that had infiltrated through the tailings cell cover.
3.2.10 Duration ofSimulations and Time Steps
Simulations were run to predict 200 years into the fiJture as rcquired by thc Permit.As
dcscribcd above,climatological data for the 57-year period 1932 through 1988 were
repeated to gencrate the necessary duration of input data.Climatic data were input on a
daily basis for the tailings-cover modcl.Daily flux rates predictcd by the simulations
through the tailings cover were used for input to the model of the tailings,liner,and
bedrock vadose zone.The minimum and maximum time-step lengths were I x 10>"day
(0.086 seconds)·and 0.5 days,respectivcly,enabling an initial time step of 5 x 10"'day
(4.32 seconds)for the HYDRUS-1D models.The maximum number of iterations per
timc step was 40.In HYDRUS-ID,solution ct1iciency is maximized by incorporating
adaptive-timc-step adjustmcnts based on criteria dcscribed in Simunek et al.(2005).
3.2.11 Sensitivity Analysis
A sensitivity analysis was performed to quantify the model-prediction unccrtainty due to
estimating input parameters.Three values were selected for each input parameter,
reprcsenting three different conditions such as a minimum,expected,and maximum
value.The input variables selected for analysis as part ofthe sensitivity analysis included
precipitation,liner saturated hydraulic conductivity,and dispersivity.Saturatcd thickness
of thc tailings was not included in the sensitivity analysis becausc it is a parameter that is
controlled rather than an unknown (e.g.,future precipitation,liner saturated hydraulic
conductivity,and dispersivity).Unsaturated hydraulic conductivity of the vadose zone
was not included in the sensitivity analysis because these values vary to match flux rates
under a unit hydraulic gradient.Daily predictions ofwater fluxes exiting the tailings cell
cover modcl were uscd as an upper boundary condition f(l!>the vadose-zone-transport
model.
3-14
First,the input precipitation was varied.As a worst-case sccnano,the three largest
precipitation years were insclied into the long-term meteorological timc scries,rcplacing
years of averagc prccipitation.For a maximum precipitation worst-case sccnario,the
three largest precipitation years,1957 (22.4 inches),1909 (24.5 inches),and 1906
(23.6 inches),were consceutively inserted in the data record rcplacing precipitation
values measured between 1946 and 1948 (which were 11.6,13.9,and 13.8 inches,
respectively,and are close to the long-term average of 13.3 inches).This sequcnce was
included in each 57-year record of the maximum precipitation runs.Inclusion of
consecutive-wet ycars,as recommcndcd by Khire ct a!.(2000),was used to evaluate if
long-term accumulation of water in the water-storage layer is problematic and if the ET
cover is likely to perform as designed and to evaluate the effects of increased
precipitation on water flow and potential contaminant transport in the vadose zone.
Initial simulations suggested some ponding of water on the surfacc;as a result,a
minimum SurftlCC pressure of2 cm was enablcd.This ensured that all precipitation was
accounted for.Additionally,the three smallest precipitation years were inserted into the
long-term meteorological time series,replacing years of average precipitation.
Second,the saturated conductivity of thc liner was changed to match ditTerent potential
fluxes.As a worst-case scenario,the base-casc potential flux through the liner of Cells 2
and 3 and Cells 4A and 4B (see Section 3.2.5)were increased by a factor of 2.4 to
1.1 x 10-3 and 6.2 x 10-'1 cm/day,respectively.This resulted in liner conductivities of
1.8 x 10-4 and 2.1 x 10"cm/day,for Cells 2 and 3 and Cells 4A and 4B,respectivcly.
Increasing the conductivity of the liner is expected to result in increased potential water
and solute fluxes to the aquifcr,and is conceptually equivalent to increasing the number
ofassumed liner defccts.
Third,hecause pressure heads are expeetcd to vary within the vadose zone,the
dispersivity was changed to quantify associatcd modcl uncertainty for this input
parameter.Theoretically-based sensitivity analyses prescnted in the work of Khaleel et
a!.(2002)suggest that dispersivity is strongly dependent on the mean pressure head in the
vadose zone.As a worst-case sccnario,the dispcrsivity was increased by a factor of 2.5
to 125 em,which is similar to values presentee!by Khalecl et a!.(2002).Incrcasing the
3-15
dispersivity of the vadose zone is expected to decrease the arrival time of potential
contaminant hreakthrough.Additionally,given the low unsaturated hydraulic
conductivities and fluid velocities,the dispersivity was set to zero to simulate diffusive
transport ofchloride and sulfate.
3.3 GROUNDWATER FLOW AND CONTAMINANT TRANSPORT MODELING
Two groundwatcr models were constructed:one model represented the water in the
tailings cells to evaluate tailings cell dewatering for Cells 2 and 3 and the other model
represented the perched aquifer to evaluate potential fllturc impacts to shallow
groundwater and contaminant transpOli.A tailings cell dewatering model was not
constructed j(lr Cells 4A (or 48)because analytical solutions prescnted by Geosyntec
Consultants (2007b)were deemed adequate given the uniform distribution of the drain
system in this cell.
3.3.1 Model Codes
The computcr codes MODFLOW and MT3DMS were used in this modeling emlrt with
the Depariment of Defense (DoD)Groundwater Modeling System (GMS)pre-and
post-processor.MODFLOW is a modular three-dimensional finite-dif1erence flow model
developed by the United States Geological Survey (USGS)(McDonald and Harbaugh,
1988;Harbaugh et aI.,2000)to calculate hydraulic-head distribution and determine flow
within a simulated aquitCr.MT3DMS (Zheng and Wang,1999)is an updated version of
the United States Environmental Protection Agency (U.S.EPA)'s model MT3D (Zheng,
1990)and is capable of simulating transport of multiple contaminants simultaneously.
Contaminant-transport processes that are simulated by MT3DMS inelude advection,
dispcrsion,degradation,and sorption.These models were selected because they can
adequatcly represent and simulate thc hydrogeologie conditions and potential
contaminant-transport processes that could occur in the perched aquifer beneath White
Mesa.FUlihcrmore,these models arc well-documented,fi"equently used,and versatile
programs that are widely accepted by the scientifIc and regulatory communities
(Anderson and Woessner,1992;Zheng and Bennett,1995).
-----------
3-16
3.3.2 Model Domains,Layering,and Grids
Tailings Cell Model.'[he domain for the tailings cell model is approximately 3,500 by
1,200 ft,representing the tailings cells (sec Figure 3-2),The finite-difference grid
employs a constant spacing of lOft.The model ineludes two layers to represent the
tailings and slimes drains.The bottom layer was I-ft thick and represented the tailings-
drain layer,and the top layer had a variable thickness that represents the tailings.The
water level in the top layer was allowed to vary spatially and temporally.The bottom
elevations were set based on information presented in the tailings cell construction report
(0'Appolonia Consulting Engineers,1982).
Perched Aquifer Model.The model domain for the perelied aquifer extends 12,000 ft in
the north-south direction (extending to Ruin Spring in the south)and 6,900 n in the east-
west direction (see Figure 3-3).The finitc-ditlercnee grid employs a constant spacing of
50 ft and is a single layer representing the perched aquifer in the Burro Canyon
Formation above the Brushy Basin Member.A single layer was deemed suflieient to
model groundwater flow and transport at the site,considering the limited thickness ofthe
perched aquifer and given that flow is primarily horizontal due to the extremely low
vertical hydraulic conductivity ofthe Brushy Basin Member.
3.3.3 Boundary Conditions
Boundary conditions define hydraulic constraints at the boundaries of the model domain.
There arc three general types of boundary conditions:
l.Specified head or Dirichlet (e.g.,constant head)
2,Specified flux or Neumann (e.g.,constant now,areal recharge,extraction
wells,no flow)
3.Head-dependent flux or Cauchy (e.g.,drains,evapotranspiration)
No-flow boundaries arc a special case ofthe specitled flux boundary in which the flow is
set to zero.
.__._--_._--~
3-17
Tailings Cell Model.For the tailings cell model,no-flow boundaries were assumed to
surround the domain.A net flux rate fi·om the cell was assumed across the entire domain.
This assumed !lux rate represents the combination of potential !luxes from the cell
through the liner and potential infiltration into the cell through the cover.The net !lux
rate was calculated using the average infiltration rate through the cover predicted by the
HYDRUS-]D tailings cover model and the potential nux rate through the bottom of
Cells 2 and 3 calculated by Knight-Piesold (1998).The resulting average net flux rate for
Cells 2 and 3 was 6.9 x 10-4 em/day (2.27 x 10-5 ft/day).This assumed net flux rate was
applied unifonnly across the domain and was simulated with MODFLOW as a negative
recharge rate.
The slimes drains were simulated with the Drain package in MODFLOW.Drains are
head-dependent boundary conditions in which !low varies based on the difference in
hydraulic head in the aquifer and the drain:as head in the aquifer deelines (tailings in this
ease),so does the dewatering rate.Drain cells were set along nine alignments spaced
SO-tt apart.Each drain was 600-ft long.Drains were set in the model as shown on
drawings for Cells 2 and 3 (D'Appolonia Consulting Eugineers,1982).
Perched Aquifer Model.For the perched-aquifer model,"artificial"hydraulic boundary
conditions were uscd to surround the domain due to a lack of data outside the White
Mesa Mill property boundaries (except at Ruin Spring).Specified head boundaries were
assigned along the nOlih,south,and west sides of the perehedcaquifer model,while a no-
!low boundary was assigned along the east side of the model as it ran perpendicular to
groundwater flow (see Figure 3-3).The specified heads were estimated based on
perched-water levels measured at the site.
A constant net areal recharge was assigned to the entire model domain,except for areas
beneath the tailings cells during transport simulations.The nct areal recharge is the
combined total of the recharge less evapotranspiration.Evapotranspiration was not
simulated explicitly in the model but rather was assumed in the net areal recharge term.
Recharge was estimated to be 3 x 10-4 cm/day (9 x 10.6 ft/day),or 0.3 percent ofaverage
annual precipitation f(lr Blanding.Average recharge rates in arid to semi-arid regions
3-18
generally represent 0.1 to 5%of the long-term average annual precipitation (Scanlon
et aI.,2006).These percentage-based global-recbarge rates are in agreement with values
obtained in southwestern Utah through a comprehensive study performed by the
U.S.Geological Survey (Heilweil et aI.,2006)at a site which has a similar climate
(although slightly hotter and drier)and geology as compared to White Mesa.Natural
recharge rates through the vadose zone estimated by Hcilweil et al.(2006)were
calculated to range from 6.6 x 10-4 to 1.6 x 10-2 em/day based on tritium analyses and
8.2 x 10-5 to 3.6 X 10-3 em/day based on chloride analyses.Average recharge beneath the
tailings cells was assigned based on results of the HYDRUS-I D model of the tailings
ee11s and bedrock vadose zone.
Several sma11 ponds that impact groundwater flow directions exist within the model
domain.These ponds were simulated using general head (Cauchy)boundary conditions,
for which a head and conductance is assigned and flux into or out of the model is
calculated.Heads in these ponds were based on water levels measured nearby and were
varied during calibration.
3.3.4 Hydraulic Properties
Tailings Cell Model.Hydraulic properties of the tailings were estimated based on
aquifer testing performed in uranium mill tailings at the Canon City Mill (MFG Inc.,
2005).The average hydraulic conductivity of the tailings ranged trom 2.1 flIday (7.4 x
10-4 em/sec)to 8.5 friday (3.0 x 10.3 em/sec)with an average value of 4.8 friday (1.7 x
10']em/sec)(MFG Inc.,2005).A hydraulic conductivity of 4.8 friday was assumed for
the tailings cell model.
Perched Aquifer Model.Hydraulic properties of the perched aquifer were based on
field and laboratory measurements.As described in Section 2.2.3,field-measured
hydraulic conductivities ranged from 5.4 x 10.4 to 4.5 ftlday.The magnitude and
distribution ofhydraulic conductivity wcrc varied during calibration.The final hydraulic
conductivities ranged betwecn 0.08 and 1 friday.A porosity of 18 percent was assumed
f(lr the modeling.This value was based on samples collected while drilling monitoring
._----_..._---
3-19
well MW-16 (Hydro Geo Chem,Inc.,2003),but also is in agreement with values for
samples collected while drilling MW-23 (sec Table 2-1).
3.3.5 Calibration of Flow Models
The calibration process involved iterating values j{lr model parameters in sequential
model simulations to produce estimated heads that hetter matched field-measured data.
After each calibration simulation,the model results were compared to known data targcts,
which in this case were piezometric-head data from monitoring wells.The initial-
parameter valucs were adjustcd through calibration until the modcl produccd results that
adcquatcly simulated the known data.As with any groundwater problem,calibration
using different combinations of parameter valnes can lcad to the same outcome for a
.given steady-state problem.Howcver,if adequate data are available to characterize the
hydrogeology and constrain the model parameters to a certain range of realistic,site-
specific values,a more unique solution will result.The general changes made through
the calibration process arc described below.
Tailings Cell Model.The tailings cell model was calibrated by varying the drain
conductance term until the How rates approximately matched the 2007 dewatering rates
(average rate of 12.5 gpm)and avcrage water levels of20 ft above the liner.
Perched Aquifer Model.The calibration was evaluated through both qualitative and
quantitative methods.Qualitatively,the simulated water table contour map and the actual
perched water table contour maps were compared visually to evaluate whether the
patterns were similar.Quantitatively,the model results were analyzed statistically using
the differences between actual target values and simulated values.The model results
were analyzed statistically using the difference between the target head and the modeled
head (this difference is known as the residual head).The calibration statistics included
(Anderson and Woessner,1992):
The mean residual (the mean difference between measured and simulated
heads);
3-20
The absolute mean residual (the mean ofthe absolute value of the differences
hetween measured and simulated heads);and
The root mean squared error (the mean of the squared ditferenees between
measured and simulated heads),
The calibration process seeks to minimize residuals,The calibration statistics for the
calibrated model arc provided in Section 4.4,The mean residual provides information on
the average error for all targets,This should be near zero;otherwise the predicted water
levels are biased,However,a mean residual ofzero does not indicate that the calibration
is acceptable,it simply indicates that the water levels are not biased high or low,The
absolute mean residual gives an indication of the total error of the model and should be
minimized,The root mean squared error is similar to the absolute mean residual,except
that it gives more weight to points with greater errOL Again,this should be minimized,
Another measure ofthe calibration is based on the root mean squared error divided by the
total head drop across the model domain,For an acceptable calibration,this normalized
root mean squared error should be less than 10 percent.Residuals also were examined
spatially to assist in adjusting parameters to achieve better correspondence between
modeled and actual-head values in subsequent calibration simulations,
Piezometric-head measurements from 26 locations (21 monitoring wells [MW-series]and
flve piezometers [P-seriesJ)spread across the White Mesa site were used for calibration
targets (see Table 3-3),To avoid biasing the calibration to a small area southeast of the
Mill Site,the chloroform wells [TW4-series]were not used as calibration targets,Water-
level-target values were the average of the four quarterly measurements for the 2007
water yeaL The range in water levels tor the !ClUr quarterly measurements was less than
3 feet during the year t()r all but two wells (MW-23 and MW-31)and less than I foot tor
15 ofthe 26 wells used as calibration targets,indicating little variation in water levels,
3.3.6 Contaminant Transport Model
Modeling of potential contaminant transport was performed for the perched-aquifer
model only,Vadose-zone modeling with HYDRUS-ID provided inputs to the
3-21
groundwater flow-and-contaminant-transport model.These inputs include both a water
flux and concentration through time at the watcr table.These potential fluxes were input
as recharge dircctly beneath the area ofTailings Cells 2 and 3 and Cells 4A and 4B.The
steady-state solution of the advective flow field was then used as tbe basis for the
transport simulations.Bccause the HYDRUS-I D model of the tailings and vadose zone
predicted that only chloride and sulfate will potentially reach the water table within
200 years,ehloride and sulfate transport was simulated in the perched aquifer.Although
there is chloride initially in the groundwater from natural sources,to clearly illustrate the
potential chloride from the tailings cells,it was assumed that there was no background
chloride in groundwater.The resulting potential chloride plume predicted by the model
can be viewed as additional chloride and can he added to the background level.The
potential concentrations of chloride were assigned as recharge-concentration sources
beneath the tailings cells,and the model was run f(llward for 200 years to assess impacts
to groundwater.
Transport Parameters.Dispersivity,degradation rates,porosity,and sorption (or
retardation)are all required as input parameters in the transport model and were
estimated from field data,laboratory data,and literature values.Becausc chloride is
considered a conscrvative tracer,it was assumed to neither adsorb nor degrade.As a
result sorption was set to zero,resulting m a retardation eoetlicient of 1.0.The
degradation rate was also set to zero.
Dispersivity.Longitudinal dispersivity of contaminants in groundwater is frequently
reported as a function of plume Icngth or transport distance.Gelhar et al.(1992)
examined many plumes and related longitudinal dispersivity (uLl to plume length (L).
Xu and Eckstein (1995)fitted a curve to the longitudinal dispersivity data presented by
Gelhar et al (1992),which was later corrected by AI-Suwaiyan (1996)and is:
This equation assumes that the measurements are in meters.Dispersivity transpOlt was
estimated based on an assumed transport distance.The I-lYDRUS-I D modeling
3-22
predicted that potential vadose zone porewater chloride concentrations beneath Cells 2
and 3 would be 0.001 mgll immediately above the water table after 127 years (see Figure
4-5 for chloride breakthrough curve).Because the potential threat to groundwater was
being assessed at 200 years,the advcctive velocity was used to calculate the transport
distance for 73 years.This resulted in a transport distance of 420 H;which was lIsed to
calculate the dispersivity.The resulting longitudinal dispersivity was approximately
17 fl.Transverse dispersivity is typically 10 percent of longitudinal dispersivity,thus it
was estimated to be of 1.7 H.
Ground Water Compliance Limit.The model predicted chloride and sulfate
concentrations were compared to the proposed GWCLs established for individual
compounds at individual wells.Proposed GWCLs are presented in the Revised
Background Groundwater Quality Report (INTERA,2(07).
3-23
TABLE 3-1
SATURATlm AND UNSATURATED HYDRAULIC I'ROI'~:RTIES
OF TIlE WIHTE MESA MILL VADOSE ZONE FLOW MODEL
Model Layer Model Layer Residual \Vatcl-Saturated Water Inverse Air l~ntl'Y Pore Size Saturated Hydraulic
IIydrostnltigraphic Model-layer Dcscl"iption Thickness Thickness Content Content (porosity)Pressure Distribution Index Conductivity
Unit and Purpose z (fI)z (em)0,.(-)0,(-)u (cm"l)II (-)K,(em/d)
Cells 2 and 3
loam frost barrier and wMcr storage"3.5 107 0.0425 0.3228 0.0186 1.339 6.3
compacted clay compacted~clay liner'31 0.068 OA07 0.0037 1.068 0.041
loam platform fill and gradinl .,91 0.0425 0.3228 0.0186 l.339 6.3
tailings tailingsd 30 914 0.035 0.323 0.0321 l.336 141>.3
sandy loam slimes drain collection systcn,c I 31 0.065 OAIO 0.0750 1.890 106.1
loam liner-protective blanketb 1 31 0.0425 0.3228 0.0186 1.339 6,3
gcomembrnl1c liner gcosynthctic lincr beneath tailingsI 1 30 0.068 OA07 0.0037 1.068 7.3 x 10-5
loam liner underlay tmel subbasegrndd\0.5 15 0.078 OA30 0.0360 1.560 24.96
vadose zone top"MW-30 35.5-36.0"13.8 422 0.004 0.199 0.0266 l.348 69.81
vadose zone middle"MW-2355.5-56.0"14.1 430 OJ)03 0.184 0.0103 1.386 9.33
vadosc zonc bottom"MW-2374.3-74.6")4.1 430 0.011>0.122 (l.()003 l.354 2A7
Cells 4A lind 4B
loam frost barrier and water storageb 3.5 107 0.0425 0.3228 0.0186 1.339 6.3
comjxlcted clay compacted-clay lind 1 31 0.01>8 OA07 0.0037 1.068 0.041
loam platfonn fiJI and grading!>3 91 0.0425 0.3228 0.0186 1.339 6.3
tailings tailingsd 30 914 0.035 0.323 0.0321 1.336 146.3
loamy sand gconct-dminage system'0.1 3 0.057 OA10 0.1240 2.280 350.2
geomembrane liner geosynthetic liner beneath tailings!1 30 0.068 OA07 0.0037 1.01>8 9.2 x 1(('
geosynthetic-clay liner geosynthetic-clay liner beneath gcomembranek 0.03 I 0.068 OA07 0.0037 1.01>8 0.024
loam liner underlay and subbase gradc'-~0.5 15 0.078 OA30 0.031>0 1.5(,0 24.96
vadose zone topa MW-30 35.5-36.(l'13.2 402 0.004 0.199 0.0266 1.348 ()9.8 I
vadose zone middle"MW-2355.5-56.0"13.5 410 0.003 0.184 0.010.1 l.386 9.33
vadose zone bottom"MW-23 74.3-74.6"13.3 407 0.016 0.122 0.0003 1.354 2A7
aThe vadose zone was subdivided into three hydrostratigraphic units based on hydrogeologic properties and the minimum separation distance between the bottom
ofthe tailings cells (Cells 2 and 3 and Cells 4A and 413)and the water-table surface beneath the tailings cells.
b Hydraulic properties predicted llsing the soil-propcl1ies database in HYDRUS assuming an average grain size comprised of43%sand,41.5%silt,
nnd 15.5%clay nnd a dry-bulk density of 1.71 g/cn?(TITAN Environmental Corporation,1996,Appendix D).
C Compacted-clay van Cienuchten parameters from Tinjum et a!.(I997.Table 5,Soil F).Soil-type F selected based on soil classification ofborrow-source materials
described in the reclamation plan (International Uranium Corporation,20(0).Compacted-clay satumted-hydrau!ic conductivity (4.7xI07 cm/s)taken from
(Jeosyntec Consultants (2006,Table 1).Residual-water content taken from the HYDRUS soil-properties database for a clay soil texture.
d Hydraulic properties predicted lIsing the soil-properties database in HYDRUS assuming an average grain size comprised of56%snnd,34%silt,and 10%clay
(Colorado School ofMines Research Institute,1978)<llld tailings bulk-dry density (1.67 g/cm')taken from TITAN Environmental Corporation (]996,Appendix D);
percent sand measured while percent clay assumed.Saturated hydraulic conductivity taken from MFG.Inc.(2005).
C Hydraulic properties predicted using the soil-properties database in I-IYDRUS assuming a sandy loam soil texture.
f Unsaturated hydraulic properties 3ssuIl1ed equal to values represented by the compacted clay described above.The saturated hydraulic conductivity was obtained
by cal ibrating nodal fluxes ofthe geomembrane Iiner to values determined by Knight-Picsold (1998),as explained in the text.
~Hydraulic properties predicted using the soil-properties database in HYDRUS assuming a loam soil texture.
h Hydraulic properties ofcore samples measured by Daniel B.Stephens &Associates (2007).The residual-water content is assumed equal 10 moisture conditions
measured at -851,293 cm.Core-depth intervals measured in feet below land surface.
,Hydraulic properties predicted using the soil-properties database in HYDRUS assuming a loamy sand soil texture.
J Unsaturated hydraulic properties assumed equal to values represented by the compacted clay described nbove.The saturated hydraulic conductivity was obtained
by calibrating nodal fluxes ofthe geomembrane liner to values determined llsing the methodology described in F:oose ct al.(2001),as explained in the text.
k Unsaturated hydraulic properties assumed equal to values reprcsented by the compacted clay described above.The saturated hydraulic conductiVity was obtained
from the literature (Jo et nl.,20(5),and reduced one order ofmagnitude <.lS suggested by Kashir and Yanful (200!).
TABLE 3-2
PHYSICAL AND CHEMICAL PROPERTIES OF TilE WlIITE MESA MILL
VADOSE ZONE TRANSPORT MODEL
Chloride Sulfate Uranium Dry Bulk Volumetric Water Sulfate Soil-water Sulfate Uranium Soil-water Uranium
l-Iydrostratigr'lphie Model L<lyer Descriptioll Dispersivity Oispersivity Dispersivity Oensity Conten{Partition Coefficicnt(l Retardation Coefficient Partition Coefficienf'Retardation Coefficient
Unit .and Purpose (em)(em)(em)Pb (mg/cmj
)0(-)K"(JIlL/mg)R (-)Kd (mL/mg)R (-)
vadose zone topa MW-30 35.5-36.0"50 50 0 1980 0067 2 x 10-6 1.07 8.47 x 10-3 251
vadose zone middle"MW-2355.5-56.0"50 50 0 2030 0089 3 x 10.6 1.01 1.04 x 10-2 239
vadose zone bottom"MW-2374.3-74_6"50 50 0 2330 0_121 0 0
aThe vadose zone was subdivided into three hydrostratigraphic units based on hydrogeologic properties and the minimum groundwater elevation
used to represellt the perched water table beneath the tailings cells.
b Dry-bulk density measured from core samples Daniel 13.Stephens &Associates (2007).Core-depth intcrval mcasured in nbelow ground surface.
C Volumetric-water content predicted with HYDRUS-}D for Cells 2 and 3 base-case scenario.
d Predicted using the geochemical code PHREEQC (Appendix B).Only adsorption ofuranium and sulfate onto hydrolls-ferric oxide present in the bedrock was considered.
EvapotranspirationPrecipitationu.o::Ow
u:J ~[~~~~~~-AtmosPheric Upper Boundary Condition
g ~{I~.'.:i:--'229 em~o::o ~_(7.5 feet)~~~~~~
-'-'~-'-Free Drainage Lower Boundary Condition0=>-~Model predicted nux (used in HYDRUS-1D Model of tailings,iiner,
J:and bedrock vadose zone and in MODFLOW Model of tailings)
,----"---,-Variable Specified Flux Upper Boundary Condition
TAILINGS
(UNSATURATED)
DAKOTA
SANDSTONE
BURRO CANYON
FORMATION
914 em
(30 feet)Pressure head =0(atmospheric)
I-Jr...----I-Inilial saturaled thickness predicted by MODFLOW model 01
lailings cell (122 em for Cells 2and 3,30 cm for Cells 4A and 48)
Initial Contaminant
TAILINGS Concentrations
(SATURATED)4,608 mg/L chloride
64,914 mg/L sullate
94 mg/L uranium
CELLS ~~~~~~~CELLS2AND3{}4AAND4B
106cm 49 em
(3.5 feet)(1.6 feet)
CELLS
2AND 3
1282 em
(42 feet)
CELLS4AAND4B
1219 em
(40 feet)
Cl W
ZZ::J2~~-0~o~~="~gu.o::00--,Wwm
00Oz:i:<o -~o::oW"'z:>-0::--'
0--'>---'J:wu
DENISON MINES (USA)CORP,
WHITE MESA MILL
MODELING APPROACH AND
HYDRUS-1 D MODEL DOMAIN
AND BOUNDARY CONDITIONS
FIGURE 3-1
----'-Fixed Pressure Lower Boundary Condition
Waler table (pressure head =0 [atmospheric])
SEE TABLES 3-1 AND 3-2 FOR LAYER THICKNESSES AND
PARAMETER VALUES USED IN HYDRUS·1D MODELS
Model predicted water flux and contaminant concentrations
(used in MODFLOW and MT3DMS Model of Perched Aquifer)
MODFLOW and MT3DMS Model of Perched Aquifer
;;,
~
~;;:1-.1
FILE Fig 3-2 Dennison tailings CellDomain_1007.ai 10116107 SLC
,
L ~-~...
EXPLANATION
-No-flow boundary
onrmrom:l Slimes drains
-
NW*E
S
o
Scale in Feel
400
DENISON MINES (USA)CORP.
WHITE MESA MILL
MODFLOW TAILINGS CELL
MODEL DOMAIN,GRID,AND
BOUNDARY CONDITIONS
FIGURE 3-2
~.-
(")
o
1-
.J I 4.-_p ..:t ,
EXPLANATION 1,
Specified head boundary 1-No-flow boundary !
General head boundary II
~water level calibration
target (mOnitoring well)AL
V water level calibration
target (piezometer)
4.0 RESULTS
This section presents the results from the vadose zone infiltration and contaminant
transport modeling as wcll as the groundwater flow and contaminant transport modeling.
The HYDRUS-ID model was used to predict potential water fluxes through the tailings-
cover system (results presented in Section 4.1).The model-predicted flux at the bottom
boundary of the cover-systcm model (potential flux predicted through the cover)was
used as input to the MODFLOW model to predict tailings cell dewatering and the
HYDRUS-ID model to predict potential flow and transport through the tailings, tailings
cell liner system,and bedrock vadose zone to the perched aquifer.The results of the
groundwater modeling performed with MODFLOW to predict dewatering of the tailings
cells are presented in Section 4.2.Water levels predicted with MODFLOW to remain in
the tailings after dewatering were also used as input for the HYDRUS-ID vadose zone
flow and contaminant transport model.Rcsults of the vadose zone flow and transport
modcling (i.e.,model-predicted flow and contaminant transpOlt through the tailings,
tailings cell liner system,and underlying bedrock vadose zone to the perched aquifer)are
presented in Section 4.3.The potential water flux and contaminant concentrations
(combincd to get contaminant mass flux rates)predicted at the bottom boundary (perched
aquifer water table)ofthe HYDRUS-ID model were used as input to the perched aquifer
groundwater flow and contaminant transport model (MODFLOW and MT3DMS).
Results of groundwater flow and contaminant transport modeling of the perched aquifer
are presented in Section 4.4.The results of the sensitivity analysis are dcscribed In
Seetion 4.5.Key modeling assumptions and model uncertainty are discussed In
Section 4.6.For ease of comparison to model files,wherever possible,units of measure
used in the models havc bcen retained in the text (i.c.,fect and days for MODFLOW,
centimetcrs and days for HYDRUS-ID,and mgll for both MT3DMS and HYDRUS-ID).
4.1 TAILINGS CELL COVER SYSTEM MODELING
The HYDRUS-10 model was used to predict potential water fluxes through the tailings-
cover system assuming atmospheric boundary conditions and a cover design as presented
in Figure 3-1.All precipitation was assumed to enter the model domain (infiltrate at least
4-1
into layer I);no runoff was assumed.Water was then removed through
evapotranspiration,stored within the cover system,or transported downward through the
cover system.The model-predicted flux rate through the cover was used as input to the
MODLOW model of the tailings cells and the HYDRUS-I D model of the tailings cells
and bedrock vadose zone.
The tailings-cover model was run for 228 years,repeating the 57-year climatic record
four times.To reduce the impacts from transient changes in storage and equilibration of
initial conditions,water fluxes predictcd for the fourth 57-year period were used as input
into the other models;howcver flux ratcs predicted for the first,second,and third 57-year
periods were very similar to the fourth.The model-predicted daily flux rates through the
tailings ccll cover for one 57-year period are shown on Figure 4-1.The model-predicted
water flux rate varies during the 57-year period from a minimum rate of
7.4 x 10-6 cm/day to a maximum rate of 2.0 x 10-3 cm/day,with an average flux rate
through the cover system of 1.0 x 10-4 cm/day.The model predicted flux rates through
the covcr system are in agreemcnt with values repOlied for similar ET cover systems
under similar climatic conditions (Section 2.1.2).The averagc flux rate was assumed for
the rcchargc ratc to the tailings dewatering MODFLOW model.The transient flux rates
(daily predictions)wcre used for input into the HYDRUS-ID model of the tailings,
tailings-liner systems,and bedrock vadose zone for Cclls 2 and 3 and Cells 4A and 4B.
4.2 TAILINGS CELL DEWATERING MODELING
The tailings cell dewatering simulated with MODFLOW was performed to cstimate
future dewatering rates and water levels within Cells 2 and 3.The average water level in
Cell 2 in 2007 was used for initial conditions.In 2007,the average depth to water
measured in Cell 2 was approximately 10 feet,leaving a maximum saturated thickness of
approximately 20 feet and an avcrage saturated thickness of approximately 14 feet.
Cell 3 was assumed to be fUlly saturated initially since dewatering operations have yet to
begin.
The MODFLOW tailings cell model predicts that as water levels decline in the tailings
due to dewatering,pumping rates will decline as well.The averagc water level (saturated
4-2
thickness)in the tailings is predicted to decline to approximatcly 4 ft after 10 years of
pumping for Cell 2 and 14 years for Cell 3 (see Figure 4-2).The model predicts that
dewatering rates will decline to approximately 2 gpm after 10 and 14 years ofpumping in
Cells 2 and 3,respectively.These pumping rates are the maximum sustainable constant
pumping rates the system can yield if pumped continuously.While higher sh011-tenn
pumping rates could be obtained by temporarily discontinuing dewatering operations,
allowing water levels to re-cquilibrate,and then resuming pumping (i.e.,pulsing);the
average pumping rate could not exceed the continuous pumping rate.This reduction in
pumping rates is caused by the reduction in saturated thickness of tailings.Dewatering
rates are also controlled by the saturated hydraulic conductivity of the tailings.If the
actual hydraulic conductivity of the tailings is higher than the value assumed in the
model,dewatering rates could be higher and water levels could be lowered more rapidly.
Conversely,if the actual hydraulic conductivity of the tailings is lower than the value
assumed in the model,dewatering rates could be lower and water levels could require
more time to dewater.
A dewatering model was not constructed for CeIls 4A and 4B because dewatering rates
were estimated by Gcosyntec Consultants (2007b).Water levels in Cell 4A were
estimated to decline to less than I foot after 5.5 years ofdewatering.Cell 4A is estimated
to be dewatered significantly faster than CeIls 2 and 3 due to the more extensive slimes
drain network.The dewatering system in Cell 4B is assumed to be designed similarly to
Cell 4A,thus dewatering rates were assumed to be similar.
4.3 TAILINGS AND VADOSE ZONE FLOW AND TRANSPORT MODELING
The HYDRUS-ID vadose-zone model was used to predict potential flow rates and
contaminant transport rates from the tailings,through the tailings cell liner system,and
through the bedrock vadose zone to the perched aquifer.The infiltration rate varies
through time and is predicted by the HYDRUS-ID model of the tailings cover
(infiltration data input to the HYDRUS-ID model ofthe tailings ceIl and vadose zone on
a daily basis).The average saturated thickness of the tailings was assumed to be 4 ft
(122 em)for Cells 2 and 3 and I ft (30 em)for CeIls 4A and 4B at the beginning ofthese
4-3
simulations.Active dewatering was assumed to have been discontinued prior to the start
of the vadose zone modeling.Water flux rates will be discussed first followed by
containinant transport.
4.3.1 Saturated Thickness of Tailings :lIld Flux Rates Beneath Tailings Cells
The predicted pressure heads in the tailings (i.e.,saturated thickness of tailings)for
Cells 2,3,4A,and 4B (post-active dewatering)predicted by HYDRUS-ID are shown in
Figure 4-3.The water level (i.e.,saturated thickness)in the Cells 2 and 3 tailings was
predicted to slowly decline through time reaching 39 em (1.3 ft)at 200 years,primmily
as a result of potential flux through defects in the liner.However,this decline is a net
decline and is a result of the combined effect of the potential f1ux out of the cell through
the liner and potential input of water from infiltration through the cover.The pressure
heads in the tailings ofCells 4A and 4B were predicted to decline through time reaching
unsaturatcd conditions (ncgative prcssures)after 135 years (Fib'llre 4-3).
The model-predicted flux rate through the liner varies as a function ofthe head (saturated
thickness)above the liner.On average,model-predicted f1ux rates through the liner
exceed infiltration rates through the cover.For short periods,potential infiltration rates
through the cover are predicted to exceed potential f1ux rates through the liner,during
which times water levcls temporarily incrcase in the tailings (for example,between years
50 and 55 on Figure 4-3).However,the pressure head (saturated thickness of tailings)is
not predicted to exceed the initial water level in Cells 2 and 3 (122 em [4 ft])or Cells 4A
and 4B (30 em [I it]),as shown on Figure 4-3.Thus the model predicts that water will
not oveliop the maximum liner c1evation (pressure head equal to approximately 914 em
[30 ft)),evcn without active dewatering.
The model-predicted water flux rates through the vadose zone to the perched aquifer for
Cells 2 and 3 and Cells 4A and 4B vary through time as shown on Fib'llre 4-4 (time =0 is
assumed when active dewatering is tcrminated).The flux rate through the bedrock
vadose zone for Cells 2 and 3 is predicted to decline rapidly from an initial rate of
9.0 x 10-4 cm/day (see Figure 4-4).After approximately 15 years,when the head in the
tailings cells is 109 em (3.6 ft),the potential flux rate is predicted to be 4.6 x 10-4 cm/day
4-4
and then gradually declines to 2.5 x 10-4 cm/day at 200 ycars.For Cells 4A and 4B,the
model-predicted flux rate through the bedrock vadose zone is initially 5.2 x 10-4 cm/day,
but rapidly decreases to 3.0 X 10-4 cm/day after seven years,then gradually declines to
1.4 x 10.4 cm/day at 200 years.
Onee quasi-steady-state conditions have been achieved,the model-predicted flux rate
through the liner is generally the same as the model-predicted flux rate to the perched
aquifer (with some differences in timing).This is because the flux rate approaches the
unsaturated hydraulic conductivity (at steady state)through the bottom of the liner and
the water content ofthe vadose zone adjusts such that the value of unsaturated hydraulic
conductivity corresponds to thc prescribed flux.As a result,the model results are not
sensitive to the unsaturated hydraulic conductivity properties of the vadose zone
materials as long as conditions do not approach saturation.
Initially,model-predicted flux rates through the liner excecd the modcl-prcdicted steady-
state flux through the cover because of the saturated conditions in the tailings cells in
addition to potential infiltration through the cover.However,the model-predicted flux
rate through the liner and the perched aquifer slowly dcclines through time as the water
levels in the tailings decline.Slight variations caused by variations in fluxes through the
tailings cell cover resulted in variations in the decline of the tailings water levels.The
saturated tailings attenuated most of the variability associated with infiltration through
the eover.If the tailings become unsaturated throughout their entire thickness,then the
potential flux through the liner and bedrock vadose zone would be very similar to the
rates predicted for flux rates through the tailings cell cover.
4.3.2 Contaminant Concentrations and Mass Flux Rates
Chloride.The model-predicted breakthrough curve for chloride (vadose zone porewater
conccntration versus time)at thc bottom of the vadose zone beneath Cells 2 and 3 is
shown on Figure 4-5 and beneath Cells 4A and 4B is shown on Figure 4-6.The
breakthrough curve presented represents the model-predicted addition of chloride as a
result of flux from the tailings cells.While there is naturally-occUlTing chloride in the
vadose zone initially,the modeling assumed no initial ehloride for simplicity,and
4-5
because thcre is a lack of data concerning background chloride and distribution of
chloride in the vadose zone.Furthermore,these arc the predicted chloride concentrations
in vadose zone porewater that will reach the perched aquifer;however these are not the
predictcd concentrations in groundwater.These vadose zone chloride concentrations for
Cells 2 and 3 and Cells 4A and 4B were uscd as input for mass-loading terms in the
pcrchcd aquifer model (input to the MODFLOW and MT3DMS model),whieh was used
to predict concentrations in groundwater.Bencath Cells 2 and 3,chloride is predicted to
reach the bottom of the bedrock vadose zone at a concentration of 0.001 mgll at
127 years and at a conccntration of 0.1 mgll at 177 ycars,as shown on Figure 4-5.
Chloride concentrations are predicted to reach the bottom of the vadose zone at a
concentration of0.39 mgll at 200 years beneath Cclls 2 and 3.Bcneath Cells 4A and 4B,
a chloride concentration of0.01 I mgll is predicted to rcach the bottom ofthe vadose zone
at 200 ycars,as shown on Figure 4-6.
The mass flux rate is a function of the chloride concentrations predicted to migrate
through the vadose zone (Figure 4-5 or 4-6)and the water flux rates predicted through the
vadose zone (Figure 4-4).Based on these assumptions,the model-predicted maximum
chloride mass flux rate is approximately 9.8 x 10-8 mglcm2 per day at 200 years for
Cells 2 and 3_The model-predicted chloride mass flux rate at the bottom of the vadose
zone beneath Cells 4A and 4B is predicted to be approximately 1.6 x 10-9 mglcm2 per day
at 200 years.
Sulfate.The model-predicted breakthrough curve for sulfate (vadose zone porewater
concentration versus time)at the bottom of the vadose zone beneath Cells 2 and 3 is
shown on Figure 4-7_Sulfate beneath Cells 4A and 4B is not shown because it is
predicted to be at concentrations of less than 1.0 x 10-3 mgll at 200 years.The
breakthrough curve presented represents the model-predicted addition of sulfate as a
result of the potcntial flux from the tailings cells.While there is naturally-occurring
sulfate in the vadose zone initially,the modeling assumed no initial sulfate for simplicity.
These vadose zone sulfate concentrations for Cells 2 and 3 and Cells 4A and 4B were
used as input for mass-loading tcnus in the perched aquifer model (input to the
MODFLOW and MT3DMS model),which was used to predict sulfate concentrations in
4-6
groundwater.Beneath Cells 2 and 3,sulfate is predicted to reach the bottom of the
bedrock vadose zone at a concentration of0.001 mg/I at 152 years,and at a concentration
of 0.09 mg/I at 200 years,as shown on Figure 4-7.Sulfate conccntrations are predicted
to reach the bottom of the vadose zone at a concentration of 3.2 x 10-4 mg/l at 200 years
beneath Cells 4A and 4B.
The model-predicted mass flux rate is a function ofthe sulfate concentrations predicted to
migrate through the vadose zone (Figure 4-7)and the water flux rates predicted through
the vadose zone (Figure 4-4). Based on these assumptions,the model-predicted
maximum sulfate mass flux rate is approximately 2.3 x 10-8 mg/cm2 per day at 200 years
for Cells 2 and 3.The model-predicted sulfate mass flux rate at the bottom of the vadose
zone beneath Cells 4A and 4B is predicted to be approximately 4.3 x 10-11 mg/cm2 per
day at 200 years.
Uranium.The model-predicted distribution of uranium in the vadose zone beneath the
tailings cell liner at 200 years is shown on Figure 4-8.Due to the strong sorption and the
resulting high-retardation coefficients,uranium is not predicted to migrate much beyond
20 cm (8 inches)below the liner system in 200 ycars beneath Cells 2 and 3 and Cells 4A
and 4B.At 30 cm (1 ft)below the liner at 200 years,dissolved-phase uranium
concentrations are predicted to be 3.0 x 10-4 mg/l beneath cells 2 and 3 and
2.0 x 10-8 mg/l bcneath Cells 4A and 4B.No uranium is prcdieted to reach the perched
aquifer within 200 years.While there is some naturally-occurring uranium in the vadose
zone initially,the modeling assumed no initial uranium for simplicity,and because there
is a lack of data concerning background uranium and distribution of uranium in the
vadose zone.Uranium concentrations presented on Figure 4-8 represent the predicted
uranium concentration in vadose zone porcwater above background levels.The predictcd
distribution ofuranium bcncath the liner assumes the tailings cells are the only source of
uranium.Dissolved uranium concentrations were assumed to rcmain at a concentration
of94 mg/l in the tailings.
4-7
4.3.3 Sorption,Retardation,and Potential Migration of Other Contaminants
Sorption coefficients and retardation factors were calculated for contaminants ofpotential
concern to assess their potential transport through the bedrock vadose zone.To calculate
sorption coefficients for potential contaminants of concern,two geochemical processes
were assumed to control solute-transport mobility in the vadose zone:adsorption of
solutes onto HFO and precipitation ofminerals.However,other sorption processes may
occur,fUIiher slowing potential contaminant migration.The calculated KI values and
retardation factors are considered conservative since only one iron-oxyhydroxide phase
was considered to participate in surface-complexation reactions (e.g.,adsorption of
metals onto goethite,montmorillonite,and quartz were not included in the model)and
eopreeipitation of metals onto the surfaces of precipitating phases (e.g.,hydrous-fenie
oxide,sulfates,carbonates)was ignored.Details regarding the methodology to predict
sorption coefficients and geochemical-modeling results arc included in Appendix B.
The distribution coefficients and retardation factors for the potential contaminants of
concern are presented in Table 4-1.Solutes predicted to have high KI values resulting in
high retardation factors and low mobility include arscnic,beryllium,chromium,copper,
lead,uranium,vanadium,and zinc.Similarly to uranium,these contaminants are not
prcdieted to migrate through the vadose zone to the perched water table in 200 years,
given their high retardation factors.Solutes predicted to have intermediate Kd values
include cadmium,cobalt,manganese,molybdenum,and nickel.These contaminants also
arc not predicted to migrate through the vadose zone to the pcrched water table in
200 ycars.Solutes predictcd to have low Kd values include selenium and sulfate;while
iron,fluoride,mercury,silver and thallium were predicted to migrate unretarded,like
chloride.This assumes that there is no sorption or any other loss mechanisms such as
degradation,precipitation,or other transformations.Based on Kd values reported in
Sheppard and Thibault (1990),U.S.EPA (1996),and U.S.EPA (1999),sorption and
retardation of cadmium,cobalt,iron,manganese,mercury,nickel,selenium,silver,and
thallium are likely to be significantly larger than model-prcdictcd values presented in
Table 4-1.As a result only chloride,sulfate,and fluoride are predicted to migrate with
4-8
little or no sorption.Potential concentrations of these contaminants are predicted in
groundwater and described in Section 4.4.2.
Sorption generally is greatest in the middle vadose zone unit,which contains sufficient
buffering minerals capable of neutralizing the low-pH fluids prescnt in the tailings (see
Table 4-I).Neutralization of infiltrating tailings porewaters was calculated for each
individual bedrock unit,and not with an iterative (pseudo-reactive transport)approach,
which also was considered a conservative approach.Specifically,if a more sophisticated
approach were used in which water chemistry changes were modeled along with
contaminant transport through the vadose zone,then larger retardation factors would
result,particularly for the deepest bedrock unit.
4.4 GROUNDWATER MODELING RESULTS
The MODFLOW and MTJDMS perched-aquifer model was used to predict groundwater
flow and potential contaminant transport in the perched aquifer.The groundwater flow
model results will be discusscd first followed by contaminant transport.
4.4.1 Groundwater Flow Model Calibration
Both qualitative and quantitative methods used to evaluate the calibration of the
groundwater-flow model indicated that the model adequately represents the actual
groundwater-flow conditions in the perched aquifer for the calibration period.The
model-simulated piezometric surface contours for the perched aquifer are depicted in
Figure 4-9 (compare to Figure 2-5 depicting contours from measured water levels).In
general,model-predicted flow directions and water levels reasonably represent observed
conditions.
For the groundwater-flow model of the perched aquifer,the mean error,absolute mean
error,and root mean squared erTors (RMSE)were calculated by comparing simulated
water levels to observed water levels for 26 water level targets (water levels in
monitoring wells and piezometers)distributed tlu'oughout the domain.The mean error
was 0.4 ft,indicating that on average the model simulated actual water levels reasonably
4-9
well (e.g.,the model did not systematically over prediet or under predict water levels
across the site).The mean absolute error was 4.3 ft and the RSME was 5.1 ft.Given the
average total head drop was 185 ft across the perched aquifer model domain,the
normalized RSME was 2.8 %,indicating an acceptable calibration (generally anything
less than 10 %is eonsidered aceeptable [Rumbaugh and Rumbaugh,2001]).
Volumetric Flow Budget.Water fluxes into the groundwater-flow model include areal
recharge from precipitation,fluxes from wildlife ponds,potential fluxes from the tailings
cells,and water entering through upgradient specified-head boundaries (groundwater
flow fi'OIn upgradient of model domain).Water leaves the groundwater-flow model
through specified-head boundaries,which ineludes simulation ofgroundwater flow to the
aquifer beyond the model domain and discharge to seeps and springs where the perehed
aquifer outcrops (e.g.,Ruin Spring).The overall mass balance error for the flow model
was 0.1 %(2 ft3/day with a total flow of2,244 ft 3/day).Areal recharge from precipitation
accounted for 26 %ofwater entering the model,while fluxes from the wildlife ponds and
potential fluxes from the tailings cells (Cells 2,3,4A and 4B)aceounted for 67 %and
6 %,respectively,ofthe flow cntering the model.Specified-head boundaries represented
less than 2 %of flow entering the model,but 100 %ofthe flow leaving the model.
4.4.2 Contaminant Concentrations and Distribution in Groundwater
The groundwater contaminant transport model was used to predict chloride and sulfate
transport and concentrations in the perched aquifer resulting fl-om potential fluxes from
the tailings cells.As with the vadose zone modcl,this model was run for a 200-year
period and chloride and sulfate concentrations predicted are additional eoneentrations
above background levels.Baekground levels were set at zero in the model so as not to
obscure the impaets to groundwater chloride and sulfate concentrations eaused by
assumed fluxes from the tailings cells with the spatial and temporal variability of
background concentrations.
The Pennit stipulates that concentrations of contaminants in f,'Toundwater monitoring
wells shall not exceed specified GWCLs.Downgradient monitoring wells with GWCLs
specified in the Permit include MW-5,MW-11,and MW-12,loeated on the berm
4-10
immediately south (downgradient)of Cell 3,and MW-14 and MW-15,located on the
berm immediately south (downgradient)of Cell 4A.The maximum model-predicted
chloride and sulfate concentrations in groundwatcr at monitoring wells MW-5,MW-II,
MW-12, MW-14,and MW-15 at 200 years are presented in Table 4-2.GWCLs for
chloride and sulfate in these wells were proposed in the Revised Background
Groundwater Quality Report (INTERA,2007)and also are presented in Table 4-2.Due
to the low mass flux rates predicted to reach the aquifer,chloride and sulfate
concentration increases at these wells due to the tailings cells are insignificant,and fall
far below laboratory detection limits.At 200 years,the modeled fluxes from the tailings
cells are predicted to increase chloride by less than 0.03 %of the proposed GWCLs in all
monitoring wells.The modeled fl.uxes hom the tailings cells are predicted to increase
sulfate by less than 0.0002 %of the proposed GWCLs.
Most of the other potential contaminants of concern are retarded relative to chloride and
sulfate,and as a result,are not predicted to reach the perched water table aquifer at
200 years.Given the magnitude of impacts predicted to groundwater for chloride and
sulfate (minimal),the impacts caused by the other mobile contaminant (fluoride)was
estimated.Using dilution/attenuation of chloride from tailings fluids to groundwater as a
proxy,the concentration of fluoride was estimated.The average chloride and fluoride
concentrations in the tailings fluids were 4,608 and 1,694 mgll,respectively (Utah
Division of Radiation Control,2004).Because the monitoring well predicted to be
impacted the most by potential releases from the tailings cells is monitoring well MW-12,
the fluoride concentration was estimated for this location.Assuming a dilution factor of
768,000 (chloride concentration in tailings [4,608 mgll]divided by ehlOIide concentration
predicted in groundwater at monitoring well MW-12 from assumed tailings fluxes at
200 years [0.006 mgll]),a fluoride concentration of 0.002 mgll was estimated for
MW-12.The proposed GWCL for fluoride in MW-12 is 2 mgll.As a result,the
predicted concentrations of fluoride as well as other contaminants of concern are not
predicted to exceed proposed GWCLs at 200 years.
4-1 I
4.5 SENSITIVITY ANALYSIS
Vadose Zone Flow and Transport Model.A sensitivity analysis was perfonned to
evaluate the impacts that uncertainty in parameter valucs have on model results.The
input parameters selected as part of the sensitivity analysis included the precipitation
record,saturated hydraulic conductivity of thc liner,and vadose-zone dispersivity.To
compare the model output for the sensitivity-analysis,the chloride concentration at the
bottom ofthe vadose-zone model at 200 years (for each simulation)was compared to the
base-case scenario.In addition,the change in ehloride concentration from the base-case
scenario was also computed.Only chloride in Cells 2 and 3 was simulated in the
sensitivity analysis.The base-case scenario was represented by the measured
precipitation record,a saturated hydraulic conductivity of the liner equal to 7.3 x 10.5
cm/day (which was obtained during calibration),and a presumed dispersivity of 50 cm.
The results ofthe sensitivity analysis are tabulated in Table 4-3.
As compared to the base-case scenario,the saturated hydraulic conductivity ofthe liner
appcared to more significantly affect chloride transport through the vadose zone than the
other parameters that were varied (see Table 4-3).Increasing the liner eonductivity by a
factor of 2.4,which was equivalent to increasing the assumed number ofliner defects by
a factor of 2.4,resulted in a chloride concentration of 16.5 mgll predicted to be migrating
through the vadose zone at 200 years,which is approximately 40 times greater than the
base case value (see Table 4-3).Increasing the dispersivity by a factor of 2.5 resulted in
a chloride eonccntration of7.5 mgll at 200 ycars,which is approximately 19 times !,'Teater
than the base case value (see Table 4-3).However,ifanything,the base case dispersivity
is overestimated.Inserting thc three wettest years (1909,1906,and 1957)into the
precipitation time-series record back-to-back in place of 1946-1948 data (see
Section 3.2.11 for a detailed description)resulted in a chloride concentration of 3.1 mgll
at 200 years,which is a factor of eight increase in the chloride concentration relative to
the base case.
As a worst-case scenario,assuming a wet precipitation record,incrcased dispersivity,and
increased liner conductivity,a chloride concentration of 252 mgll was predicted to reach
4-12
the base of the vadose zone beneath Cells 2 and 3 at 200 years.A similar run was
perfonned for Cells 4A and 4B and resulted in a chloride concentration of 65 mgll
predicted to reach the base ofthe vadose zone at 200 years.
The worst-case scenario as identified with chloride transport (i.e.,high precipitation,
increased liner hydraulic conductivity,and increased dispersivity)was run for sulfate
transport.A sulfate concentration of 1,257 mgll was predicted to reach the base of the
vadose zone beneath Cells 2 and 3 at 200 years.A similar run was performed for
Cells 4A and 4B and resulted in a sulfate concentration of218 mgll predicted to reach the
base ofthe vadose zone at 200 years.
The worst-case scenario as identified with chloride transport (i.e.,high precipitation,
increased liner hydraulic conductivity,and increased dispersivity)was also run for
uranium transport.Uranium concentrations in vadose zone porewater were predicted to
reach 3.0 x 10-4 mgll above background concentrations at a depth of32 em (1 ft)beneath
the liner ofCells 2 and 3 at 200 years,compared to 30 em for the base ease.For Cells 4A
and 4B,under these worst-case conditions,uranium at a concentration of 1.5 x 10-4 mgll
was predicted to migrate 31 cm beneath the liner at 200 years.Given the magnitude of
the retardation faetors,uranium transport is predicted to remain minimal (i.e.,on the
order of a few feet into the Dakota Sandstone)despite large changes in advective
velocities.
The unsaturated hydraulic conductivity of the vadose zone was not evaluated because the
moisture content in the vadose zone varies until the unsaturated hydraulic conductivity
csscntially becomes equal to the flux rate (at steady state),so vadose zone model results
are typically relatively insensitive to changes in the unsaturated hydraulic conductivity,
except at high water contents,when the unsaturated hydraulic conductivity approaches
the saturated hydraulic eonductivity.
Groundwater Flow and Transport Model.A full sensitivity analysis of the
groundwater model was not perfonned,but the results of what was considered to be the
worst-case sccnario identified through the sensitivity analysis for the vadose zone model
were input to the groundwater flow and transpOit model to evaluate the impact to
4-13
groundwater quality for this "worst case."The "worst-case"for the vadose zone model
included using wet prccipitation record,which included insertion of the three maximum
precipitation years back-to-back (sec Section 3.2.11 for dctails),increased dispersivity,
and incrcased liner fluxes.Undcr thcsc worst-case conditions,chloride was predicted to
reach a pore-watcr concentration of 252 mg/l beneath Cells 2 and 3 and 65 mg/l beneath
Cells 4A and 4B at the bottom of the vadose zone at 200 years.Sulfate was predicted to
reach a pore-water concentration of 1,257 mg/l beneath Cells 2 and 3 and 218 mg/l
beneath Cells 4A and 4B at the bottom of the vadose zone at 200 years.Under these
worst-case conditions the average watcr fluxes were predicted to be 7.5 x 10-4 and
5.0 x 10-4 cm/day beneath Cells 2 and 3 and Cells 4A and 4B,respectively.Using this as
input to the groundwater model,the maximum chloride and sulfate concentrations (above
background)under worst-case conditions were predicted to occur at monitoring well
MW-12 at concentrations of II and 48 mg/I,respectively.The proposed GWCLs for
chloride and sulfate at monitoring well MW-12 are 80.5 and 2,560 mg/l,respectively.
4.6 UNCERTAINTY AND ASSUMPTIONS
The numerical modeling presented in this report was based on fundamental physical
assumptions conceming the mechanisms controlling flow and solute transport in the
vadose zone and perched aquifer.However,as with all numerical models,the model
only replicates the actual physical system to the extent that it is based on an accurate
conccptual model that describes the site hydrogeology,boundary conditions,and initial
conditions.The goal of the conceptual model is to describe these conditions (e.g.,
stratigraphy,hydraulic properties,transport mechanisms,and boundary conditions)with a
sufficient level of detail to address the objectives of the study.Because the subsurface
environment is heterogcneous,the conceptual and numerical models need to make
simplifying assumptions so that the physical characteristics of the system can be
quantified and incorporated into the numerical model.One ofthe most basic assumptions
for a subsurface fate and transport model is that the subsurface stratigraphy and hydraulic
propcrties are adequately characterized.
4-14
The hydraulic properties of the tailings were assumed in the MODFLOW model
constructed to predict tailings cell dewatering rates.If the actual hydraulic conductivity
of the tailings is higher than the value assumed in the model,dewatering rates could be
higher and water levels could be lowered more rapidly.Conversely,if the actual
hydraulic conductivity of the tailings is lower than the value assumed in the model,
dewatering rates could he lower and water levels could require more time to dewater.
Furthermore,the hydraulic conductivity of the tailings could vary spatially which could
impact dewatering rates.
Some of the simplifications include assuming the vadose zone is one thickness beneath
Cells 2 and 3 and Cells 4A and 4B.In the model,the vadose zone (distance between the
liner beneath the cells and the perched aquifer water table)was assumed to be 42 ft for
Cells 2 and 3 and 40 ft for Cells 4A and 4B.This vadose-zone thickness is the minimum
dcpth to thc watcr table (measured in nearby monitoring wells),which only occurs in one
small area.The depth from the bottom of the cells to the perched aquifer water table is
up to 90 ft in some areas.This assumption is conservative as it results in shorter travel
times for contamination to reach the water table.Actual travel times are likely to be
much greater than predicted,particularly for transport beneath the western halfofCells 2
and 3 where the vadose zone is much greater than 42 ft thick.
There is considerable evidence that the cells are not leaking.However,flux rates through
the tailings cell lincr system wcre calculated using standard equations and assumptions to
account for potcntial defcets in the flexihle-membrane liners.With these estimated flux
rates,hydraulic conductivity values for the liner used in HYDRUS-ID to simulate leaks
had to be estimated.The resulting hydraulic conductivity values for the PVC and HDPE
liners are average values for the entire tailings cell area to account for potential
manufacturing defects,punctures,and tears in the liners.
Leakage from the unlined wildlife ponds have resulted in significant impacts to the
perched water table surface (see Figure 2-5),which is not evident beneath the tailings
cells.Given that these tailings cclls have contained tailings at ncarly fully-saturated
4-15
conditions for close to 25 years,if leakage were significant it is likely that evidence
would have appeared at this point.
Hydraulic propeliies of the vadose zone were based on a limited data set (six cores from
two boreholes).However,as previously discussed,ifconditions are unsaturated (and not
close to saturation)as they likcly are in the bedrock vadose zone at White Mesa,the
unsaturated hydraulic conductivity essentially becomes the same as the flux rate (at
steady state)and the water content of the vadose zone adjusts such that the value of
unsaturated hydraulic conductivity corresponds to the prescribed flux.As a result,the
model results are not sensitive to the unsaturated hydraulic conductivity properties of the
vadose zone materials as long as conditions do not approach saturation.Hydraulic
propeliies ofthe tailings cover materials were estimated based on grain-size distribution.
The bedrock vadose zone was assumed to not be fractured in the modeling.Under
unsaturated conditions,fractures will tend to act as barricrs to flow similar to a capillary
break,particularly if they are open.Under saturated conditions,fi'actures can act as
prcfercntial pathways to flow.Groundwatcr-rccharge studies at a site which has a similar
climate (although slightly hottcr and drier)and geology as compared to White Mesa
indicates that rccharge to the aquifer through the vadose zone is via matric flow through
primary porosity rather than through fractures (Heilweil et aI.,2006).
The vadose-zone model of the cover assumed that all precipitation infiltrated at least into
the top layer of the model (i.e.,no precipitation was assumed to runoff).This is
considered to be slightly conservative,but given how flat the cover is (0.2 %slope),it is
a realistic assumption.
The vadose-zone model assumed no lateral flow,only veliical flow.This ignores the
impacts that horizontal heterogeneities may have on migration in the vadose zone.
Because there is so little information concerning vadose-zone heterogeneities,a two-or
three-dimensional model could not be constructed with a large degree of certainty.
However,given that hydraulic gradients in the vadose zone are strongly vertical,flow is
primarily vertical,and thus a one-dimensional model is adequate for vadose zone flow
and transport.
4-16
Vadose zone modeling of the tailings,liner system,and underlying bedrock vadose zone
was assumed to begin when active dewatering (i.e.,pumping the slimes drains)was
assumcd to be discontinucd.Thus the HYDRUS modeling only included drainage ofthe
tailings through assumed Icaks in the liner rather than active pumping.The duration of
active pumping (estimated to be 14 years or less)was minimal relative to the overall
period of the simulations,and was assumed to be completed before the 200 year period
began.
The HYDRUS-I D vadose zone flow model cannot be calibrated bccause there are no
moisture content or pressure head data available for the vadose zone.Quantifying
moisture fluxes through desert vadose zones is very difficult due to the small magnitude
of fluxes and the very long response times (Walvoord et aI.,2002).Furthermore,the
transport component cannot be calibrated because there are no contaminant data available
for the vadose zone.
The vadose zone modeling assumes a uniform density fluid.Density affects the
hydraulic gradient and hydraulic conductivity values.However,the impacts that density
has on these is minimal relative to the impacts that moisture contents have on unsaturated
hydraulic conductivity.As a result,the impact of ignoring dcnsity effects in the vadose
zone is likely minimal.
The vadose zone modeling docs not account for vapor transport.Under natural
conditions,watcr transport in thick dcsert vadosc zoncs is dominated by upward vapor
transport ovcr vcry long time periods (Walvoord et aI.,2002).Modeling performed by
Walvoord et al.(2002)indicatcs that most thick desert vadose zones are in a slow drying
proccss that is on the ordcr oftcns ofthousands of years.Upward vapor transport would
act to slow downward contaminant migration.
Another key assumption is that future climatic conditions will be similar to past climatic
conditions within the historical record.It is uncicar what impacts global wanning may
have on the climate and how these changes will impact tailings cell cover performance.
However,speculating on the possible impacts of global warming to climatic conditions is
bcyond the scope ofthis report.
4-17
TABLlC 4-1
DISTRIUUTION (Kd)COlCFFICIENTS AND RETARI>AnON FACTORS (R)
FOR SELECTED CONTAMINANTS PRESENT IN THE TAILINGS PORE FLUIDS WHITE MESA MILL VADOSE ZONE ".b
Arsenic Beryllium Cadmium Chromium Cobalt Copper Fluoridec Irollc Lead ManganescC Mercury lVlolybdcnum Niekel Selenium Silver Sulfate"Thallium Uranium V:lIladium Zinc
Vadose Zone K"K"Kd K"K" K"K"K"K"Kd K"K"](d K"Kd Ktl K"Kd K"Kd
I-lydrostratigraphic Unit (I/kg)(I/kg) (I/kg)(I/kg)(I/kg)(I/kg) (I/kg)(I/kg)(I/kg)(I/kg)(I/kg)(I/kg)(I/kg)(I/kg)(I/kg)(I/I<g)(I/kg)(I/kg) (I/kg)(I/kg)
top 7.19 82.1 0.001 0.557 0.000 4.13 0.000 0.000 9A8 0.001 0.000 0.014 0.005 0.015 0000 0.002 0.000 8A7 0.000 0.009
middle 7094 72140 1.033 4.90 0.115 1220 0.0003 0.000 2197 0.901 0.000 0.663 1.380 0.015 0.000 0003 0.000 lOA 559 11.3
bottom 0.119 0000 0.000 0000 0.000 0.000 0.000 0.000 0.000 0.000 0000 0.000 0.000 0.001 0.000 0.000 0000 0000 0.000 0.000
R R R R R R R R R R R R R R R R R R R R
H H H H H H H H H H H H H H H H H H H H
top 213 2428 1.02 17 1.00 123 1.00 1.00 281 1.02 1.00 IA1 1.14 1A6 1.00 1.07 1.00 251 1.00 1.26
middle 161804 1645434 25 113 3.63 27822 1.01 1.00 50105 22 1.00 16 32 1.34 1.00 1.07 1.00 239 12744 260
bottom 3.30 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.01 1.00 1.00 1.00 1.00 1.00 1.00
a Methodology and a~sumptjons used to determine sorption coefficients are described in Appendix B.
bAverage volumetric-water conlent of the underlying vadose zone units were predicted with the HYDRUS~ID base-case scenario for Cells 2 and 3.
C Sorption coefficients for fluoride,rnanganesc,and sulfate were COITcctcd to account for precipitation of fluorite,pyrolusite,and gypsum/barite,respectively.
Note:Based on K{]values reported in Sheppard and Thibault (1990),U.S.I:YA (1996),and U.S.EPA (1999),sorption and retardation of cadmium,cobalt,iron,manganese,mercury,nickel,selenium,silver,and thallium arc likely to be significantly larger than
model-predicted values.
TABLE 4-2
iYIODEL-PREDICTED CHLORIDE At'iD SULFATE CONCENTRATIONS
IN GROUNDWATER
Model-Predicted Chloride Chloride GWCLs Model-Predicted Sulfate Sulfate GWCLsMouitoringWellConcentration(mg/I)Concentration (mg/I)(mg/I)(mg/I)
MW-5 0.005 17.0 0002 1,518
M\V-Il 0.003 39.2 0.001 1,309
MW-12 0.006 805 0.003 2,560
MW-14 1.30E-05 270 0 2,330
MW-15 1.30E-05 57.1 0 2,549
TABLE 4-3
MODEL-PREDICTED CHLORIDE CONCE1'iTRATlONS
AT THE BOTTOM OF THE VADOSE ZONE FOR CELLS 2 AND 3 EVALUATED AS PARTOFTHE SENSITIVITY ANALYSIS
~ut Parameter Varied
1\'lodel Run"Precipitationh Oispersivity~K>~{geomembrane
Minimum Oem LOW
2 Minimum SOem LOW
3 t'vlinimum J25 em LOW
4 i'vlinimum Oem BC
5 Minimum 50 em BC
6 Minimum 125 em BC
7 Minimum Oem HIGH
8 Minimum 50 em HIGH
9 Minimum 125 em HIGH
10 Average Oem LOW
II Average 50 em LOW
12 Average 125 em LOW
13 Average Ocm BC
14 Average 50 em BC
15 Average 125 em BC
16 Averngc Oem HIGH
17 Average 50 em HIGH
i8 Average 125 em HIGH
19 rVlaximum Oem LOW
20 Maximum 50 em LOW
21 Maximum 125 em LOW
22 Maximum aem BC
23 Maximum 50 em BC
24 Maximum 125 em BC
25 Maximum Oem HIGH
26 Maximum 50 em HIGH
27 i\:laximum 125 em HIGH
Response Variable Evaluated Response Variable St<nistic
Chloride Concentration at the Change in Chloride Concentration at the
Bottom of the Vadose Zone at 200 yr Bottom of the Vadose Zone at 200 yr
(mg/L)(mg/L)
o -0.4
o -0.4
0.1 -0.3
o 44
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7.4 7.0
0.1 -0.3
16.2 15.8
85,2 84.8
0 -0.4
0 -0.4
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0 -0.4
0.4 0.0
7.5 7.1
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16.5 16.1
86.0 85.6
0 -0.4
0 -0.4
0.7 0.3
0 -0.4
3.1 2.7
33.3 32.9
1.8 1.4
77.3 76.9
251.8 251.4
;\Model run 14 \vas selected as tbe base-case scenario.
b The maximllm~prccipitationrecord \vas obtained by inserting the three wettest years into the average precipitation time-series record,whereas
the minimum-precipitation recorded was obt8ined by inserting the three driest years into the average precipitation time-series record.
C A dispcrsivity of zero indicates only diffusive transport ofchloride is considered.
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BENEATH CELLS 4A AND 4B
FIGURE 4-6
File:Fig 4-7 Sulfate concentrationS_1107,ai 1112012007 SLG
0.20
0.15
'"'"-0lJ
=~
=.S;;
E
C 0.10""§
U
"~=CJ1
0.05
0.00
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,--_._..._..._._._----~.~.-.~--~---_.._._.,-------_.__..~-----:
-.---.-...._._----------~-_.--..---"-_.._..__.--~-------.._------~....-
......._._----~"-_._.-------."...""'-------....._..._-------
I
o 50 100
Time (year)
150 200
DENISON MINES (USA)CORP.
WHITE MESA MILL
MODEL-PREDICTED SULFATE CONCENTRATIONS
IN VADOSE ZONE PORE WATER
IMMEDIATELY ABOVE THE PERCHED AQUIFER
BENEATH CELLS 2 AND 3
FIGURE 4-7
Fife:Fig 4-8 Dissolved Uranium in Vadose_200yr_1107.ai 11/20/2007 SLC
Dissolved Uranium Concentration (mgIL)
o 10 20 30 40 50 60 70 80 90 100
--I
'\.--..~"..•_..----------,-_..•.._.•._-
-_.~_..•......._------~~10
'-"::;:3
o I I I I I I ).},I I
""Q,.=30 -ll~~~~~-
0:;
U
'"OJ)::
~
'"o0:;:::
40 -1"--'
DENISON MINES (USA)CORP_
WHITE MESA MILL
MODEL-PREDICTED DISSOLVED URANIUM
CONCENTRATIONS IN VADOSE ZONE
PORE WATER AT 200 YEARS
FIGURE 4-8
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,
I,;
JI
r
;i
r
I
(
.~-(.
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--,:-
,.
DENISON MINES (USA)CORP.
WHITE MESA MILL
MODFLOW MODEL·PREDICTED
PIEZOMETRIC SURFACE CONTOURS
PERCHED AQUIFER
FIGURE 4·9
i
I "./"h,r I ,I,-)/,
((/~IT
Ftet
1I',
Jf..,~I
•,
(/'
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Water level calibration
target (monitoring well)
General head boundary
Specified head boundary
Piezometric surface contour
Water level calibration
target (piezometer)
EXPLANATION
•
v
_No·now boundary
"\'t \-./',-j
),
I,J
+"T ,.VI
I
I
1;(
)
l)
iii
~'<-;~t
~~1--1-"-'':''-----------------''------'--------'-------------------1gN,_Water level calibration targets are
",I average of 4 water levels measured •~in 2007water year W E
Q Base map adaptedfrom USGS 7.5 Minute:g Topographic maps ofalack Mesa Butte.
<:Blanding South,No-Mans Is/and,~and Big Bench,Utah Quadrangles.0 S 2000
~Coordinates are UTM Zone 12,;;
~NAD 1927 meters."L...1
5.0 CONCLUSIONS AND POST-AUDIT MONITORING PLAN
This section summarizes the rcsults ofinfiltration and contaminant transport modeling to
support Denison's Groundwater Discharge Permit f(lr the White Mesa uranium milling
and tailings disposal facility and provides recommendations for a post·audit monitoring
plan.
5.1 CONCLUSIONS
Modeling of the tailings ccll covcr with HYDRUS-!D indicated that with slight design
modifications to the multilayered cover as presented in the Tailings Cover Design
(TITAN Environmental Corporation,1996)and the Reciamation Plan.Revision 3.(J
(International Uranium (USA)Corporation,2000),infiltration can be reduced
significantly (averagc long-term infiltration rates were reduced from 1.0 x 10'2 cm/day
for the original cover design to 1.0 x 10-4 cm/day for the modificd cover design,a
reduction of two orders-of~magnitude).With a vegetated ET cover,the HYDRUS-ID
model predicts that the potential flux rate through the cover could range between
7.4 x 10'6 cm/day and 2.0 x 10'3 em/day,with an average flux rate through the cover
system of 1.0 x 10-4 cm/day,Cover design modifications can include replacing the
cobble layer with 6 inches of topsoil with gravel and vegetation,as well as increasing the
frost barrier/water storage laycr from 2 to 3 ft.As specified in Part LH.II of the Permit,
the Permittee may include supplemental information to justify modification of certain
Permit requirements,including tailings cell cover system engineering design and
construction specifications.Upon Executive Secretary approval of the final infiltration
and contaminant transport repOli,the Reclamation Plan may be modified to accommodate
necessary changes to protect public health and the environment
Modeling of the tailings dewatering system with MODFLOW suggests that it is not
practical to fully dewater the tailings in Cells 2 and 3.Modeling predicted that
dewatering rates would decline to approximately 2 gpm aftcr 10 and 14 additional years
of pumping fi-om Cells 2 and 3,respectively,leaving 4 ft of saturated tailings on average.
The reduction in pumping rates is caused by the reduction in saturated thickness of
•..•~,-------,._-----
5-1
tailings.Cells 4A and 4B have a more extensive slimes drain network and were assumed
to be dewatered after approximately fIve years.
Modeling of potential flow ii-OlD the tailings through the liner and underlying bedrock
vadose zone was performed with HYDRUS-I D.The model-predicted flux rate through
the liner varies as a function of the head (saturated thickness)above the liner.On
average,model-predicted flux rates through the lincr excccd infiltration rates through the
cover.For short periods,potential infiltration rates through the cover are predictcd to
exceed potential flux rates through the liner,during which times water levels temporarily
increase in the tailings.However,the pressure head (saturated thickness of tailings)is
not predicted to exceed the initial water level in Cells 2 and 3 (122 cm [4 ft])or Cells 4A
and 4B (30 cm [1 ft]),as shown on Figure 4-3.Thus the model predicts that water will
not overtop the maximum liner elevation (pressure head equal to approximately 914 cm
[30 ft]),even without active dewatering.
Modeling of potential flow fi-OlD the tailings through the liner and underlying bedrock
vadose zone was performed with HYDRUS-I D.Maciel-predicted flux rates through the
bedrock vadose zone beneath Cells 2 and 3 deeline rapidly from an initial rate of
9.0 x 10-4 em/day,then gradually decline to 2.5 x I0-4 cm/day at 200 years.For Cells 4A
and 4B,the model-predicted flux rates through the bedrock vadose zone decline rapidly
i1·om an initial rate of 5.2 x 10-4 cm/day,then gradually decline to a steady-state rate of
i.4 x ]()-4 cm/day by approximately 175 years aner the tailings are predicted to have
become unsaturated.We have assumed potential defects in the liner and have made other
assumptions that may overestimate any potential f1uxes from the tailings cells.In reality,
the actual f1ux rates may be lower than model-predicted values or there may be no f1ux at
all.
Modeling of potential chloride and sulfate transport f1·om the tailings through the tailings
cell liner and bedrock vadose zone was also performed with HYDRUS-1 D.Beneath
Cells 2 and 3,chloride and sulfate concentrations in pore water at the bottom of the
bedrock vadose zone arc predicted to increase to concentrations of 0.39 and 0.09 mgll,
respectively,at 200 years.Beneath Cells 4A ancl 4B,chloride ancl sulfate concentrations
5-2
in porewater at the bottom of the vadose zone are predicted to increase to concentrations
01'0.011 and 3.2 x lOA mg/I,respectively,at 200 years.Chloride was assnmed to migrate
unretarded (i.e.,no sorption)through the vadose zone.Sulfate was assumed to have a
maximum retardation factor of 1.07,such that it is considered highly mobile,but it is
slightly retarded relative to chloride.These are the model-predicted chloride and sulfate
concentrations in vadose zone porewater that will reach the perched aquifer;however
these arc not the predicted concentrations in groundwater.
Modeling of chloride and sulfate transport in the perched aquifer was performed with
MODFLOW and MT3DMS.The Permit stipulates that concentrations of contaminants
in groundwater monitoring wells shall not exceed specified GWCLs.Downgradient
monitoring wells with GWCLs specilled in the Permit inelude MW-5,MW-Il,and
MW-12,located on the berm immediately south (downgradicnt)of Cell 3,and MW-14
and MW-15,located on the berm immediately south (downgradient)ofCe1l4A.Due to
the low mass flux rates predicted to reach the aquifcr,model-predicted chloride and
sulfate concentration increases at these wells due to the tailings cells are insignificant,
and fall far below laboratory detection limits.At 200 years,the modeled fluxes from the
tailings cells are predictcd to increase chloride by less than 0.03 %of the proposed
GWCLs in all monitoring wells.The modeled fluxes fi-om the tailings cells are predicted
to increase sulfate by less than 0.0002 %ofthe proposed GWCLs.
Retardation rates for uranium were calculated bascd on equilibrium soil-water partition
coefllcients ([(<I)using thc mass of BFO present in the bedrock and the equilibrated
solution compositions predicted with thc geochemical code PBREEQC.Neutralization
of the inllltrating tailings porewaters and sorption of solutes was determined with
PBREEQC.The mass of BFO and calcite werc determined for samples collected fi·om
the vadose zone for corc samples from the Dakota Sandstone and Burro Canyon
Formation.Through this method,a SOIlJtion value for the Dakota Sandstone immediately
beneath the tailings cells was estimated to be 8.47 kg/L.Assuming a volumetric moisture
content of7%,a retardation factor of 251 was calculated.
5-3
Modeling of potential uranium transport from the tailings through the tailings cell liner
and into the vadose zone was pertonned with HYDRUS-l D.Due to the strong sorption
and the resulting high-retardation coeffIcients,uranium is not predicted to migTate much
beyond 20 cm (8 inches)below the liner system in 200 years beneath Cells 2 and 3 and
Cclls 4A and 4B.At 30 cm (I ft)below the liner at 200 years,dissolved-phase uranium
concentrations arc predicted to be 3.0 x 10-4 mgll beneath Cells 2 and 3 and 2.0 x 10.8
mgll beneath Cells 4A and 4B.No uranium is predicted to reach the perched aquifer
within 200 years.Wbile there is some naturally-occurring uranium in the vadose zone
initially,the modeling assumed no initial uranium for simplicity,and because there is a
lack of data concerning background uranium and distribution of uranium in the vadose
zone.Dissolved uranium concentrations were assumed to remain at a concentration of
94 mg/I in the tailings.Becausc uranium was prcdicted to migrate such a short distancc
in the hcdrock vadosc zone,thcrc appears to be no threat to groundwatcr posed by
uramUll1.
Sorption coefficients and retardation factors were calculatcd for contaminants ofpotential
concern to assess their potential transport through the bedrock vadose zone.Solutes
predicted to have high K"values resulting in high retardation factors and low mobility
include arsenic,beryllium,cbromium,copper,lead,uranium,vanadium,and zinc.
Similarly to uranium,these contaminants are not predicted to migrate through the vadose
zone to the perched water table in 200 years,given their high retardation factors.Solutes
prcdieted to havc intermcdiate K"values include cadmium,cobalt,manganese,
molybdenum,and nickcl.Thcse contaminants also arc not predicted to migrate through
the vadose zone to the perched water table in 200 years.Solutes predicted to have low Kd
values include selenium and sulfate;while iron,fluoride,mercury,silver and thallium
were predicted to migrate unretarded,like chloride.This assumes that there is no
sorption or any other loss mechanisms such as degradation, precipitation,or other
transformations.Based on Kd values reported in Sheppard and Thibault (1990),
U.S.EPA (1996),and u.S.EPA (1999),sorption and retardation of cadmium,cobalt,
iron,manganese,mercury,nickel,selcnium,silver,and thallium are likcly to be
signifIcantly larger than model-predicted values.As a result only chloride,sulfate,and
fluoride are predicted to migrate with little or no sorption.
5-4
Given the magnitude of model-predicted impacts to groundwater fClr chloride and sulfate
(minimal),the impact caused by the other mobile contaminant (tluoride)was estimated.
Using dilution/attenuation ofchloride from tailings fluids to groundwater as a proxy,the
concentration of fluoride was estimated.Because the monitoring well predieted to be
impacted the most by potential releases from the tailings cells is monitoring well MW-12,
the fluoride concentration was estimated fClr this location.Assuming a dilution factor of
768,000,the fluoride concentration of 0.002 mg/l was estimated filr MW-12.The
proposed GWCL for fluoride in MW-12 is 2 mg/l.As a result,the predicted
concentrations of t1uoride as well as other contaminants of concern are not predicted to
exceed the proposed GWCLs at 200 years.
Under Part I.D.6 (Closed Cell Performance Requirements)ofthe Permit:
"before reelamation and elosure of any tailings disposal cell,thc Pcrmittcc shall ensure
that the final design,construction,and operation of the cover system at each tailings cell
will comply with all requirements of an approvcd Rcclamation Plan,and will for a period
ofnot less than 200 ycars meet thc following minimum perlc)J'Jl1anee requirements:
a)Minimize infiltration of precipitation or other sUrlC\CC water into the tailings,
including,but not limited to the radon barrier,and
b)Prevent the accumulation of leachate head within the tailings waste layer that
could rise above or over-top the maximum FML liner elevation internal to any
disposal cell,i.e.create a "bathtub"effect.
c)Ensure that groundwater quality at the compliance monitoring wells does not
exceed the Ground Water Quality Standards or Ground Water Compliance
Limits specified in Part I.C.l and Table 2 ofthis Permit."
Based on the model results presented in this report,all three requirements are met by the
modified cover design.
5-5
5.2 POST-AUDIT MONITORING PLAN
To check the accuracy of the model predictions,a post-andit can be performed,oilen
referred to as model verification.Additional data are collected and after a specified
period,the model is rerun with new input data and the results al'e compared to tield-
measured data f()l'the same period.Given difficulties associated with data collection and
the time-scale on which processes occur in the vadose zone,a post audit ofthe HYDRUS
modcls is not practical.A post audit of the MODFLOW modcl for the tailings cell
dewatering is described below.Given the time-scale on which the model-predicts
contaminants could potentially reach the perched aquifer,post-audit monitoring should
include ongoing groundwater levcl measurements and groundwater sampling,but at a
reduced frequency and at a limited set ofwells relative to that currently uscd to establish
backgroundlevcls.Sampling should focus on the closest downgradient monitoring wells.
For post-audit monitoring of the dewatering system,water levels in the tailings and
pumping rates and volumes should be measured and recorded monthly,as described
above.Weather data should be obtained from the Utah Climate Center for the Blanding
weather station.The model predictions should be compared to these data.
If the dewatering rates predicted by the model are considerably diflerent than actual
measured rates,the MODFLOW model should be reealibrated by adjusting terms such as
areal recharge,hydraulic conductivity oftailings,storage parameters,and/or slimes drain
conductance to match dewatering rates and measured water levels.The HYDRUS-I D
model for flow and chloride transport through the vadose zone should be rerun with the
revised saturated thickness predictions to evaluate changes to mass loading to the perched
aquifer.If deemed necessary,the MT3DMS model of the perched aquifer can be rerun
for chloride and sulfate transport.
5-6
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Scanlon,B.R.,R.C.Reedy,K.E.Keese,and S.F.Dwyer,2005.Evaluation of
Evapotran.lpirative Covers for Waste Containment in Arid and Semiarid Regions in
the Southwestern USA.Vadose Zone Journal 4:55-71.
Scanlon,B.R.,M.Christman,R.C.Reedy,I.Porro,J.Simunek,and G.N.Flerchinger,
2002.Intercode Comparisons .fiJr Simulating Water Balance ofSurficial Sediments
in Semiarid Regions.Water Resources Research 38:1323-1339.
Schaefer,C.E.,R.R.Arands,H.A.Van Der Sloot,and D.S.Kosson,1995.Prediction and
Experimental Validation of Liquid-Phase Diffusion Resistance in Unsaturated Soils.
Joumal ofContaminant Hydrology 20:145-166.
Schuster,J.L.,1964.Root Development of Native Plants Under Three Grazing
Intensities.Ecology 45 :63-70.
Sheppard,M.1.and D.H.Thibault,1990.Default soil solid/liquid partition coefficients,
Kds,f,x four major soil types:a compendium,Health Physics,59(4):471-482.
R-5
Tinjum,J.M.,C.H.Benson,and L.R.Blotz,1997.Soil-Water Characteristic Curves for
Compacted Clays.Journal of Geotechnical and Geoenvironmental Engineering
123:1060-1 069.
TITAN Environmental Corporation,1994.Hydrogeological Evaluation of White Mesa
Uranium Mill.Prepared for Energy Fuels Nuelear,Inc.
TITAN Environmental Corporation,1996.Tailings Cover Design,White Mesa Mill,
Blanding Utah.Prepared for Energy Fuels Nuelear,Inc.Septcmber 1996.
U.S.Department of Energy,2003.Moab Ground Water Tailings Scepage Report,U.S.
Depmiment of Energy -Grand Junction Offiec,Document Number X0025700,
January 2003.
U.S.EPA,1996.Soil Screening Guidance:Technical Background Document,
Publication 9355.4-17A,2nd cd.,Office of Solid Waste and Emergency Response,
U.S.Environmental Protection Agency,May 1996.
U.S.EPA,1999.Understanding variation in pmiition coefficient,Kd,values:Review of
Geochemistry and Available Kd Values for Cadmium,Cesium,Chromium,Lead,
Plutonium,Radon,Strontium,Thorium,Tritium (31-1),and Uranium,Volume II,
Publication 402-R-99-00413,Office of Air and Radiation,U.S.Environmental
Protection Agency,August 1999.
Utah Climate Center,2007.Daily climate records were extracted liOlD the COOP
database liOiD http://elimate.usurfusu.edu/products/data.php for the Blanding,Utah
weather station (420738)on 25 January 2007.
Utah Division of Radiation Control,2004.Dra}!Ground Water Discharge Permil,
Statement of Basis Jor a Uranium Milling Facility at While Mesa,South of
Blanding.December 2004.
van Genuehten,M.Th.,1980.A Closed-Form Equation Jor Predicting the Hydraulic
Conductivity ojUnsaturated Soils.Soil Sci.Am.Jour.44:892-898.
Vogel,T.,and M.Cislerova,1988.On the Reliability of Unsaturated Hydraulic
Conductivily Calculated Fom the Moisture Retention Curve.Transport in Porous
Media 3:1-15.
Waite,T.D.,J.A.Davis,T.E.Payne,G.A.Waychunas,and N.Xu,1994.Uranium(V1)
Adsorption to Ferrihydrite:Application of a Surface Complexation Model,
Gcochimica et Cosmochimica Acta,58:5465-5478.
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Hydrodynamics:I.Equilibrium States and Response Times in Thick Desert Vadose
Zones.Watcr Rcsourccs Research 38.
R-6
Wazne,M.,G.P.Korliatis,and X.Meng,2003.Carbonate Effects on Hexavalent
Uranium Adsorption by Iron Oxyhydroxide,Environmental Science &Technology,
37:3619-3624.
Xu,M.,and Eckstein,Y.,1995.Use of Weighted Lcast-Squares Method in Evaluation of
the Relationship Betwcen Dispcrsivity and Ficld Seale.Ground Watcr 33 (6):905-
908.
Zheng,C.,1990.MTlD:A Modular Three-Dimensional Transport Modelfor Simulation
ofAdvection,Di:,persion and Chemical Reactions ofContaminants in Groundwater
S)'stems.Report to the U.S.Environmental Protection Agency.Ada,OK.170 p.
Zheng,C.,and G.D.Bennett,1995.Applied Contaminant Transport Modeling:Theory
and Practice.Van Nostrand Reinhold (now John Wiley &Sons),New York,440
pp.
Zhcng,C.and 1'.1'.Wang,1999.MT3DMS:A Modular three-dimensional Mu!tispecies
Model I,)r Simulation of Advection,Dispersion and Chemical Reactions of
Contaminants in Groundwater Systems;Documentation and User's Guide,Contract
Report SERDP-99-l,U.S.Army Engineer Research and Development Center,
Vicksburg.
R-7
APPENDIX A
UNSATURATED HYDRAULIC PROPERTIES
FOR CORES FROM WHITE MESA
Laboratory Report for
MWH Americas,Inc.
(Contract No.87146-0M)
April 27,2007
Daniel B.Stephens &Associates,Inc.
6020 Academy NE,Suite 100·Albuquerque,NewMexico 87109
April 27,2007
Mr.Doug Oliver
MWH Americas,Inc.
10619 South Jordan Gateway
South Jordan,UT 84095
[phone]
Re:DBS&A Laboratory Report for MWH Americas,Inc.;Contract No.87146-0M
Dear lvlr.Oliver:
Encloscd is thc final report for the MWH Americas,Inc.;contract No.87146-0M samples.
Please review this report and provide any comments as samples will be held for a maximum of
30 days.After 30 days samples will be returned or disposed of in an appropriate manner.
All testing results were evaluated subjectively for consistency and reasonableness,and the results
appear to be reasonably representative oftbe material tested.However,DBS&A does not
assume any responsibility for interprctations or analyses based'on the data enclosed,nor can we
guarantee that these data are fully reprcsentative of the undisturbed materials at the field site.
We recommend that careful evaluation ofthese laboratory results be made for your particular
application.
Tbe testing utilized to generate the enclosed final report employs methods that are standard for
the industry.The rcsults do not constitute a professional opinion by DBS&A,nor can the results
affcct any professional or expert opinions rendered with respect thereto by DBS&A.You have
acknowledged that all the testing undertaken by us,and the final repOli provided,constitutes
mere test results using standardized methods,and cannot be used to disqualifY DBS&A fi'Om
rendering any professional or expert opinion,having waivcd any claim ofconflict ofinterest by
DBS&A.
We are pleased to provide this service to MWH Americas,Inc.and look forward to future
laboratOly testing on other projects.If you have any questions about the enclosed data,please do
not hesitate to call.
Sincerely,
DANIEL B.STEPHENS &ASSOCIATES,INC.
LABORATORY /TEST~FACILITY
<:::::J ..L~~~/
Joleen Hines '7 '
Laboratory Supervising Manager
Enclosure
D(01iel B.Stephens &Associates,flU:.
6020 Acodcmy NE,Suite 100 505.822·9400
Albuquerque,NM 87109 FAXSOS-822·8877
Summaries
Daniel B.Stephens &Associates,Inc.
Summary of Tests Performed
Saturated 1/3.15 Bar
Initial Soil Hydraulic Moisture Unsaturated Particle Points and
Laboratory propertiesj Conductivitj CharacterisUcs3 Hydraulic Size4 Effective Particle Air Water Holding Atterberg Proctor
Sample Number (6,Po,<})CH :FH HC,PP,TH ,WP:RH Conductivity Ds,wsi H Porosity Density Permeabilily Capacity Limits Compaction
MW-2355,5-56,0 X X xix!;X;X X
MW-2374,3-74,6 X X xix::X:X X
MW-2382.7-82,9 X X X X::X1X X .
MW-23103,3-103,5 X X X X::X:X X
MW-30 35,5-36,0 X X X X;i x\X X
MW-30 44,0-44,5 X X X X:1X[X X
1 e "Initial moisture content,Pd =Dry bulkdensity.$=Calculated porosity
2 CH =Constanthead,FH =:falling head
~He =Hanging column.PP =:Pressureplate.TH =Thermocouple psychrometer.WP =Water activitymeter.RH =Relalive humIdity box
4 DS =Dry sieve.WS =WetsIeve.H =Hydrometer
Daniel B.Stephens &Associates,Inc.
Summary of Sample Volume Changes
As Received Properties Final Densities'
Final
Measured FinaJ%Final %of
Moisture Moisture Dry Bulk Dry Bulk Volume Original
Content Content Density Density Change Density
Sample Number (%gig)(cm'lcm3)(g/cm3)(g/cm3)(%)(%)
MW-23 55.5-56.0 0.3 0.7 2.03
MW-2374.3-74.6 0.6 1.4 2.33
MW-2382.7-82.9 0.3 0.7 2.10
MW-23103.3-103.5 0.8 1.4 1.84
MW-30 35.5-36.0 0.3 0.5 1.98
MW-30 44.0-44.5'1.7 3.8 2.23 2.12 (+)55%94.8%
'Final Densities:Volume change measurements were obtained after saturated hydraulic conductivity
testing and throughout unsaturated hydraulic conductivity testing.The reported values are the final sample
dimensions.
'"Sample MW-30 44.0-44.5 experienced swelling and water gain during and after the initial saturation
process.This sample also cracked horizontally during moisture retention testing.
Note:(+)denotes observed sample swelling,and (-)denotes observed sample settling.
-•••~Not Applicable,no volume change occurred.
Daniel B.Stephens &Associates,Inc.
Summary of Initial Moisture Content,Dry Bulk Density
Wet Bulk Density and Calculated Porosity
Moisture Content
As Received Remolded Dry Bulk Wet Bulk
Gravimetric.Volumetric Gravimetric Volumetric Density Density
Sample Number (%,9Lg)~_~cI112'cm3L (%,g/lJl __J'1Q,cm3/cm3)_(g/cl1:tt _(g/cm3)
Calculated
Porosity
(%)
MW-2355.5-56.0 0.3 0.7 ------2.03 2.03
MW-2374.3-74.6 0.6 1.4 ------2.33 2.34
MW-2382.7-82.9 0.3 0.7 ------2.10 2.11
MW-23103.3-103.5 0.8 1.4 ------1.84 1.85
MW-30 35.5-36.0 0.3 0.5 -----1.98 1.98
MW-30 44.0-44.5 1.7 3.8 -----2.23 2.27
NA =Not analyzed
--=This sample was not remolded
23.5
12.1
20.7
30.7
25.4
15.8
Daniel B.Stephens &Associates,Inc.
Summary of Saturated Hydraulic Conductivity Tests
K"'t Method of Analysis
Constant Head Falling Head
Sample Number (em/sec)Flexible Wall Flexible Wall
MW-23 55.5-56.0 1.1E-D4 X
MW-2374.3-74.6 2.9E-05 X
MW-2382.7-82.9 1.7E-04 X
MW-23 103.3-103.5 3.0E-03 X
MW-30 35.5-36.0 8.1E-04 X
MW-30 44.0-44.5 8.2E-06 X
Daniel B.Stephens &Associates,Inc.
Summary of Moisture Characteristics
of the Initial Drainage Curve
Sample Number
MW-2355.5-56.0
MW-2374.3-746
MW-2382.7-82.9
MW-23103.3-103.5
Pressure Head
(-em water)
o
13
35
100
510
15195
42832
851293
o
14
56
155
510
43851
851293
o
12
38
97
510
23557
851293
o
8
24
85
510
16827
32838
851293
Moisture Content
(%,em3/cm3)
18.2
17.7
17.6
15.8
8.5
3.2
2.1
0.3
12.3
12.3
12.2
11.9
11.7
4.9
1.6
16.3
15.3
15.3
14.9
9.6
3.4
0.3
20.4
19.3
19.2
14.0
6.8
3.3
2.5
0.6
Dalliel B.Stephens &Associates,Inc.
Summary of Moisture Characteristics
of the Initial Drainage Curve (Continued)
Sample Number
MW-30 35,5-36,0
MW-30 44,0-44.5
MW-30 44.0-44,5 (Volume Adjusted)
Pressure Head
(-em water)
o
7
20
74
510
23251
35081
851293
o
35
101
197
510
23353
851293
o
35
101
197
510
23353
851293
Moisture Content
(%,em3tcm3)
19,5
19,2
19,0
14,1
7.6
2.6
2,1
0.4
27,9
26.7
24.7
23.6
20.5
10.9
3.4
26.7
25,6
23.5
22.4
19.4
10.4
3.2
Daniel B.Stephens &Associates,Inc.
Summary of Calculated Unsaturated Hydraulic Properties
Oversize Corrected
a N a,Os a,a.
Sample Number (em")(dimensionless)(%vol)(%vol)(%vol)(%vol)
MW-23 55.5-56.0 0.0103 1.3860 0.00 18.38 NA NA
MW-2374.3-74.6 0.0003 1.3544 0.00 12.16 NA NA
MW-2382.7-82.9 0.0069 1.3362 0.00 16.01 NA NA
MW-23103.3-103.5 0.0287 1.3494 0.00 20.51 NA NA
MW-30 35.5-36.0 0.0266 1.3480 0.00 19.86 NA NA
MW-30 44.0-44.5 0.0074 1.2019 0.00 27.59 NA NA
MW-30 44.0·44.5 (Volume Adjusted)0.0081 1.2006 0.00 26.43 NA NA
--;::Oversize correction is unnecessary since coarse fraction <:5%ofcomposite mass
NA ;::Not analyzed
laboratory Data and
Graphical Plots
Initial Properties
Daniel B.Stephens &Associates,Inc.
<
Summary of Initial Moisture Content,Dry Bulk Density
Wet Bulk Density and Calculated Porosity
Moisture Content
As Received Remolded Dry Bulk Wet Bulk Calculated
Gravimetric Volumetric Gravimetric Volumetric Density Density Porosity
Sample Number (%,gig)(%,cm3/cm3)(%,gig)(%,cm3/cm 3)(g/cm3)(g/cm3)(%)
MW-23 55.5-56.0 0,3 0,7 -----2,03 2.03 23.5
MW-2374.3-74.6 0.6 1.4 -----2.33 2.34 12.1
MW-2382.7-82.9 0.3 0.7 -----2.10 2.11 20.7
MW-23103.3-103.5 0.8 1.4 -----1.84 1.85 30.7
MW-30 35.5-36.0 0.3 0.5 ------1.98 1.98 25.4
MW-30 44.0-44.5 1.7 3.8 ------2.23 2.27 15.8
NA :Not analyzed
--=This sample was not remolded
~~%i'Daniel B.Stephens &Associates,Inc.
Data for Initial Moisture Content,
Bulk Density,Porosity,and Percent Saturation
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2355.5-56.0
Ring Number:NA
Depth:55.5-56.0
Test Date:
Field weight'ofsample (g):
Tare weight,ring (g):
Tare weight,pan/plate (g):
Tare weight,other (g):
Dry weight ofsample (g):
Sampie volume (em'):
Assumed particle density (g/cm'):
Gravimetric Moisture Content (%gig):
Volumetric Moisture Content (%vol):
Drybulk density (g/cm'):
Wet bulk density (g/cm'):
Calculated Porosity (%vol):
Percent Saturation:
As Received
16-Mar-07
172.04
0.00
0.00
0.00
171.46
84.63
2.65
0.3
0.7
2.03
2.03
23.5
2.9
Remolded
Laboratory analysis by:D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Comments:
...Weight including tares
NA =Not analyzed
--=This sample was not remolded
,~~~r Daniel B.Stephens &A~>sociates,Inc.
Data for Initial Moisture Content,
Bulk Density,Porosity,and Percent Saturation
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2374.3-74.6
RingNumber:NA
Depth:74.3-74.6
Test Date:
Field weight'ofsample (g):
Tare weight,ring (g):
Tare weight,pan/plate (g):
Tare weight,other (g):
Dry weight ofsample (g):
Sample volume (em'):
Assumed particle density (glcm'):
Gravimetric Moisture Content (%gig):
Volumetric Moisture Content (%voJ):
Dry buik density (glcm'):
Wet bulk density (glcm'):
Caiculated Porosity (%vol):
Percent Saturation:
As Received
16-Mar·07
162.07
0.00
000
0.00
161.11
69.19
2.65
0.6
1.4
2.33
2.34
12.1
11.4
Remolded
Laboratory analysis by:D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Comments:
..Weight inclUding tares
NA :::Not analyzed
__N =:This sample was not remolded
Daniel B.Stephells &Associates,Jnc.
Data for Initial Moisture Content,
Bulk Density,Porosity,and Percent Saturation
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2382.7-82.9
Ring Number:NA
Depth:82.7-82.9
Test Date:
Field weight'ofsample (9):
Tare weight,ring (g):
Tare weight,pan/plate (g):
Tare weight,other (g):
Dry weight ofsample (g):
Sample volume (em'):
Assumed particle density (g/cm'):
Gravimetric Moisture Content (%gig):
Volumetric Moisture Content (%vol):
Dry bulk density (g/cm'):
Wet bulk density (g/cm'):
Calculated Porosity (%vol):
Percent Saturation:
As Received
16-Mar-07
152.51
0.00
0.00
0.00
151.98
72.35
2.65
0.3
0.7
2.10
2.11
20.7
3.5
Remolded
Laboratoryanalysis by:D.O'Dowd
Data enteredby:T.Bowekaty
Checked by:J.Hines
Comments:
"Weight including tares
NA =Not analyzed
~-~=This sample was not remolded
,~~~---~-~~-_._~~-
,'\,:=:DOlliel B.Stephens &Associates,Inc.
Data for Initial Moisture Content,
Bulk Density,Porosity,and Percent Saturation
Job Name:MWH AMERICAS,INC,
Job Number:LB07,0048,00
Sample Number:MW-23 103,3-103~5
Ring Number:NA
Depth:103.3-103~5
Test Date:
Field weight'ofsample (g):
Tare weight,ring (g):
Tare weight,pan/plate (g):
Tare weight,other (g):
Dry weight ofsampie (g):
Sample volume (em'):
Assumedparticle density (giem'):
Gravimetric Moisture Content (%gig):
Volumetric Moisture Content (%vol):
Dry bulk density (giem'):
Wet bulk density (gicm'):
Caicuiated Porosity (%vol):
Percent Saturation:
As Received
16-Mar-07
127,13
0,00
0,00
0,00
126,16
68,67
2,65
0,8
1.4
1,84
1,85
30,7
4,6
Remolded
Laboratory analysis by:D,O'Dowd
Data enteredby:T,Bowekaty
Checked by:J,Hines
Comments:
"Weight including tares
NA ;:;Not analyzed
~~~;:;This sample was not remolded
Dalliel B.Stephells &Associates,fllc.
Data for Initial Moisture Content,
Bulk Density,Porosity,and Percent Saturation
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-30 35.5-36.0
Ring Number:NA
Depth:35.5'-36.0'
Test Date:
Field weight*ofsampie (g):
Tare weight,ring (g):
Tare weight.pan/plate (g):
Tare weight.other (g):
Dryweight ofsample (g):
Sample volume (em'):
Assumed particle density (g/em'):
Gravimetric Moisture Content (%gig):
VOlumetric Moisture Content (%vol):
Dry bulk density (g/cm'):
Wet bulk density (glem'):
Calculated Porosity (%vol):
Percent Saturation:
As Received
16-Mar-07
170.24
0.00
0.00
0.00
169.77
85.85
2.65
0.3
0.5
1.98
1.98
25.4
2.2
Remolded
Laboratory analysis by:D.O'Dowd
Dala entered by:T.Bowekaty
Checked by:J.Hines
Comments:
..Weight including tares
NA =Not analyzed
_.=This sample was not'remolded
Dalliel B.Stephens &Associates,Inc.
Data for Initial Moisture Content,
Bulk Density,Porosity,and Percent Saturation
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-30 44.0-44.5
Ring Number:NA
Depth:44.0-44.5
Test Date:
Fieid weight'ofsample (g):
Tare weight,ring (g):
Tare weight,pan/piate (g):
Tare weight,other (g):
Dry weight ofsample (g):
Sample volume (cm3):
Assumed parllcle density (gicm'):
Gravimetric Moislure Content (%9/9):
Volumetric Moisture Content (%vol):
Dry buik density (g/cm'):
Wet bulk density (glcm3):
Calculated Porosity (%vol):
Percent Saturation:
As Received
16-Mar-07
197.08
0.00
0.00
0.00
193.77
86.88
2.65
1.7
3.8
2.23
2.27
15.8
24.1
Remolded
Laboratory analysis by:D.O'Dowd
Data entered by:T.Bowekaly
Checked by:J.Hines
Comments:
"Weight including tares
NA ::::Not analyzed
.-.'"This sample was not remolded
Saturated Hydraulic
Conductivity
Dlllliel B.Stephens &Associates,lltc.
Summary of Saturated Hydraulic Conductivity Tests
Ksat Method of Analysis
Constant Head Falling Head
Sample Number (em/sec)Flexible Wall Flexible Wall
MW-23 55.5-56.0 1.1E-04 X
MW-23 74.3-74.6 2.9E-05 X
MW-2382.7-82.9 1.7E-04 X
MW-23103.3-103.5 3.0E-03 X
MW-30 35.5-36.0 8,1E-04 X
MW-30 44.0-44.5 8.2E-06 X
Dalliel B.Stephells &Associates,Inc.
.Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-2355.5-56.0·
DatelT/me sampled:NA
Depth:55.5-56.0
Remolded or Initial
Sample Properties
Final (Post Test)
Sample Properties Test and Sample Conditions
Initial Mass (g):172.04
Diameter (em):5.369
Lenglh (em):3.738
Area (em'):22.64
Volume (em'):84.63
Dry Density (glcm 3):2.03
Dry Density (pef):126.48
Water Content (%,g/g):0.3
Water Content(%,val):0.7
Porosity (%,vol):23.5
Saturation (%):2.9
Saturated Mass (g):186.87
Dry Mass (g):171.46
Diameter (em):5.369
Length (em):3.738
Area (em'):22.64
Volume (em'):84.63
DryDensity (g/em'):2.03
Dry Density(pef):126.48
Water Content (%,g/g):9.0
Water Content (%,vol):18.2
Porosity (%,vol):23.5
Saturation (%)":77.3
Permeant Hquid used:Water
Sample Preparation:[2]In situ sample,extrudedoRemoldedSample
Number ofLifts:NA
Split:NA
Percent Coarse Material (%):NA
Particle Density(g/em'):2.65 0 Assumed 0 Measured
Cell pressure (PSI):32.0
Influent pressure (PSI):30.0
Effluent pressure (PSI):30.0
Panel Used:0A 0 B 0 C
Reading:0 AnnUlus [2]Pipette
B-Value (%saturation)prior to test":0.95
OatefTIme:3120107 1503
~Per A$TM D5084 percent saturation is ensured (S·Varue;;::95%)prior to testing,as post test saturation values may be exaggerated or skewed during depressuriZing and sample removal.
Laboratory analysis by:O.O'Oowd
Data entered by:D.O'Dowd
Checked by:J.Hines
Daniel B.Stepltens &Associates,file.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-2355.5-56.0
DalefT/me sampled:NA
Depth:55.5-56.0
Dale Time
Temp
('e)
Influent
Pipette
Reading
Effluent
Pipette
Reading
Ratio Change in
Gradient Average Elapsed (outflow to Head (NOllo k,,,TOC
(llH/llL)Flow (em')Time (st inflow)exceed 25%)(em/s)
ksat Corrected
(em/s)
14:20:05 24.0
14:21 :01 24.0
14:21 :01 24.0
14:22:20 24.2
14:22:20 24.2
14:23:39 24.2
Test #1:
20-Mar-07
20-Mar-07
Test #2:
20-Mar-07
20-Mar-07
Test#3:
20-Mar-07
20-Mar-07
Test #4:
20-Mar-07
20-Mar-07
14:19:06
14:20:05
24.0
24.0
15.00 19.40 1.36 0.17 59 1.0015.20 19.20 1.24
15.20 19.20 1.24 0.17 56 1.0015.40 19.00 1.11
16.40 19.00 1.11 0.17 79 1.0015.60 18.80 0.99
15.60 18.80 0.99 0.17 79 1.0015.80 18.60 0.86
9%
10%
11%
13%
1.15E-04
1.35E-04
1.07E-04
1.21E-04
1.05E-04
1.22E-04
9.68E-05
1.09E-04
1.08E·04
Ksat (+25%)(em/s):1.36E-04
Ksat (-25%)(cm/s):8.13E-05
Average Ksat (emlsee):
Calculated Gravel CorrectedAverage Ksat (em/sec):
I--~.-.~5-5~-:~-1-~--~------··=='-=--=--------.-==------.-..--.=--=-------.===--=---------=------.---=-----=:1-.,-I
_125E-04 ----------J'!~~~~:~1 ..".___..=l ASTM ReqUired Range (+/-25%)
.~;:;~~:~~_+-..:J,
7.50E-05 ---------',
6.50E-05 .i 0 50 100 150 200 250 300 I'
I ~~.
Daniel B.Steplteus &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-2374.3-74.6
DarelTimesampre~NA
Depth:74.3-74.6
Remolded or Initial
Sample Properties
Final (Post Test)
Sample Properties Test and Sample Conditions
Initial Mass (g):162.07
Diameter (em):5.376
Length (em):3.048
Area (em'):22.70
Volume (em 3):69.19
Dry DensITY (g!cm 3):2.33
Dry Density (pef):145.37
Water Content (%,gig):0.6
Water Content (%,vol):1.4
Porosity (%,vol):12.1
Saturation ("/0):11.4
Saturated Mass (g):169.61
Dry Mass (g):161.11
Diameter (em):5.376
Length (em):3.048
Area (em'):22.70
Volume (em 3):69.19
Dry Density (glem 3):2.33
Dry Density (pef):145.37
Water Content (%,gig):5.3
Water Content (%,vol):12.3
Porosity(%,vol):12.1
Saturation (%)':101.3
Permeant liquid used:Water
Sample Preparation:0 In situ sample,extrudedoRemoldedSample"
Number ofLifts:NA
Split:NA
Percent Coarse Material (%):NA
Particle Density(glem 3):2.65 [J Assumed 0 Measured
Cell pressure (PSI):32.0
Influenl pressure (PSI):30.1
Effluent pressure (PSI):30.0
Panel Used:[J DOE 0 F
Reading:0 Annulus [J Pipette
B-Value (%saturation)prior to test-:1.00
DatefTime:3/20/07 1500
•Per ASTM D5084 percent saturation is ensured (B-Value G::95%)prior to testing,as post test saturation values may be exaggerated during depressurizing and sample removal.
Laboratory analysis by:D.0'Dowd
Dala enteredby:D.O'Dowd
Checked by:J.Hines
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-2374,3-74.6
DatefTime sampled:NA
Depth:74.3-74.6
Dale Time
Temp
(oG)
Influent
Pipette
Reading
Effiuent
Pipette
Reading
Ratio Change In
Gradient Average Eiapsed (outflow to Head (Not to k",TOC
("H/"LLFlo",,(em~).Time (5)inflow)exceed 25%)(em/s)
ksat Corrected
(em/s)
Test#1:
20-Mar-07
20-Mar-07
Test #2:
20-Mar-07
20-Mar-07
Test #3:
20-Mar-07
20-Mar-07
Test#4:
20-Mar-07
20-Mar-07
14:30:19 24.2 15.40 19.85 3.99 0.17 6914:31 :28 24.2 15.60 19.65 3.84
14:31 :28 24.2 15.60 19.65 3.84 0.17 7914:32:47 24.2 15.80 19.4S 3.69
14:32:47 24.2 15.80 19.45 3.69 0.17 7214:33:59 24.2 16.00 19.25 3.S4
14:33:59 24.2 16.00 19.25 3.S4 0.17 8514:35:24 24.2 16.20 19.05 3.39
1.00
1.00
1.00
1.00
4%
4%
4%
4%1
3.27E-OS
2.97E-OS
3.40E-05
3.00E-05
2.96E-QS
2.69E-Q5
3.08E-OS
2.72E-05
2.86E-OS
Ksat (-25%)(emls):2.15E-05
Ksat (+,,5%)(emls):3.58E-05
ASTM Required Range (+1-2S%)
280230180
Time (s)
-----------
13080
Average Ksat (emlsec):
Calculated Gravel Corrected Average Ksat (em/sec):
.--4-.0-0-E--{)-5-c--.-------------------------------1'I
3.50E-{)5 --..-~.
_3.00E-QS -----...-..-.--------.-.--~2.50E·05 ••I-=-2.00E-OS !
~1.50E-05
"i.00E-05 -j--------
5.00E-06
O.OOE'OO +--~-_-_-_----_-----_----__---.J
30
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-2382.7-82.9
Datemme sampled:NA
Depth:82.7-82.9
Remolded or Initial
Sample Properties
Final (Post Test)
SampleProRerties Test and Sample Conditions
Initial Mass (g):152.51
Diameter (em):5.373
Length (em):3.191
Area (em 2):22.67
Votume (em'):72.35
Dry Density (glcm'):2.10
Dry Density (pet):131.13
Water Content (%,gig):0.3
Water Content (%,voi):0.7
Porosity (%,vol):20.7
Saturation (%):3.5
Saturated Mass (g):163.8
DryMass (g):151.98
Diameter (em):5.373
Length (em):3.191
Area (em 2):22.67
Volume (em 3):72.35
DryDensity (glem'):2.10
Dry Density (pet):131.13
Water Content (%,gig):7.8
Water Content (%,va!):16.3
Porosity (%,va!):20.7
Saturation (%)':78.8
Permeant liquid used:Water
Sample Preparation:0 In situ sample,extrudedoRemoldedSample
Number ofLifts:NA
Split:NA
Percent Coarse Material (%):NA
Particle Density(g/em 3):2.65 [J Assumed 0 Measured
Cell pressure (PSI):32.0
Influent pressure (PSI):30.0
Effluent pressure (PSI):30.0
Panel Used:0 D [J E 0 F
Reading:0 Annulus [J Pipette.
B-Value (%saturation)prior to test':0.95
Datemme:3/19/07 1305
..PerASTM 05084 percent saturation is ensured (BNalue ~95%)prior to testing.as post test saturalion values maybe exaggerated during depressurizing and sampte removal.
Laboratoryanalysis by:D.O'Dowd
Data entered by:D.O'Dowd
Checked by:J,Hines
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LBO?0048.00
Sample number:MW-2382.?-82.9
DatefT/me sampled:NA
Depth:82.?-82.9
Date Time
Temp
("e)
Influent
Pipette
Reading
Emuent
Pipette
Reading
Gradient Average Elapsed
(L>HltlL)Flow (em')Time (5)
Ratio
(outfiow to
inflow)
Change in
Head (Not.o
exceed 25%)
ksat T"e
(emls)
ksat Corrected
(emls)
Test #1:
19-Mar-0?
19-Mar-0?
Test #2:
19-Mar..Q?
19-Mar-0?
Test #3:
19-Mar-0?
19-Mar-07
Test #4:
19-Mar-0?
19-Mar-0?
13:32:09 23.6 13.20 18.00 1.?4
13:32:50 23.6 13.50 17,70 1.52
13:32:50 23.6 13.50 17,70 1,52
13:33:33 23.6 13.80 17.40 1.30
13:33:33 23.6 13.80 17.40 1.30
13:34:37 23.6 14.10 1?10 1.09
13:34:37 23.6 14.10 17.10 1.09
13:36:02 23.6 14.40 16.80 0.8?
0.26
0.26
0.26
026
41
43
64
85
1.00
1.00
1.00
1,00
13%
14%
1?%
20%
1.99E-04
2.19E-04
1.?4E-04
1.61E-04
1.83E-04
2.01E-04
1.60E-04
1.47E-04
Average Ksat (em/sec):
Calcu/ated Gravel Corrected Average Ksat (em/sec):
1.73E·04
"~I ~2.00E·04 --+f 1.50E~04-••.•.~i 1.00E-04 f J
5.00E-05 I
O.OOE+OO
30 80 130 180 230
Time (s)
ASTM Required Range (+/-25%)
Ksat (-25%)(cm/s):1.30E-04
Ksat (+25%)(cm/s):2.16E-04
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-23103.3-103.5
DarelTimesampred:NA
Depth:103.3-103.5
Remolded or Initial
Sample Properties
Final (Post Test)
Sample Properties Test and Sample Conditions
Initial Mass (g):127.13
Diameter(em):5.362
Length (em):3.041
Area (em 2):22.58
Volume (em 3):68.67
Dry Density (g/cm 3 ):1.84
Dry Density(pc!):114.69
Water Content (%,gig):0.8
Water Content (%,val):1.4
Porosity (%,vol):30.7
Saturation (%):4.6
Saturated Mass (g):140.16
Dry Mass (g):126.16
Diameter (em):5.362
Length (em):3.041
Area (em2):22.58
Volume (em'):68.67
Dry Density (g/cm 3 ):1.84
Dry Density (pc!):114.69
Water Content (%,gig):11.1
Water Content (%,val):20.4
Porosity (%,vol):30.7
Saturation (%j':66.5
Permeant liquid used:Water
Sample Preparation:0 In situ sample,extrudedoRemoldedSample
Number of Lifts:NA
Split:NA
Percent Coarse Material (%):NA
Particle Density(g/cm3):2.65 []Assumed 0 Measured
Cellpressure (PSI):32.0
Influent pressure (PSI):30.0
Effluent pressure (PSI):30.0
Panel Used:0 DOE []F
Reading:0 Annulus 0 Pipette
B-Value (%saturation)prior to test':0.95
Daternme:3/19/07 1306
•Per ASTM 05084 percent saturation Is ensured (SNalue ~95%)prior to testing,as post test saturation values may be exaggerated during depressurizing and sample removal.
Laboratory analysis by:D.O'Dowd
Data entered by:D.O'Dowd
Checked by:J.Hines
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-23103.3-103.5
Daterrlme sampled:NA
Depth:103.3-103.5
Influent Effluent Ratio Change in
Temp Pipelle Pipette Gradient Average Elapsed (outnow to Head (Not to ksat Toe ksat Corrected
Date Time ("C)Reading Reading (LlH/LlL)Flow (em')Time (s)inflow)exceed 250/0)(em/s)(em/s)
Test #1:
19-Mar-07 13:52:17 23.8 15.90 20.35 1.69 1.17 11 1.00 13%3.46E-03 3.16E-Q319-Mar-07 13:52:28 23.8 16.20 20.05 1.46
Test #2:
19-Mar-07 13:52:28 23.8 16.20 20.05 1.46 1.17 15 1.00 16%2.97E-03 2.71 E-0319-Mar-Q7 13:52:43 23.8 16.50 19.75 1.23
Test #3:
19-Mar-07 13:52:43 23.8 16.50 19.75 1.23 1.17 16 1.00 18%3.35E-03 3.06E-0319-Mar-07 13:52:59 23.8 16.80 19.45 1.01
Test #4:
19-Mar-07 13:52:59 23.8 16.80 19.45 1.01 1.17 19 1.00 23%3.55E-03 3.24E-0319-Mar-07 13:53:18 23.8 17.10 19.15 0.78
AverageKsat (em/sec):3.04E-03
Calculated Gravel Corrected Average Ksat (em/see):
I
4.00E-03 -------
3.50E-03 ------------I•3.00E-03 -•-----...i 2.50E-03 ---------_._---I ASTM Required Range (+/-25%)2-2.00E-03 ------1ii 1.50E-03•----------.I I Ksat (-25%)(emls):2.28E-03'"1.00E-03 --_.------_._-------j
5.00E-04 I Ksat (+25%)(em!s):3.81 E-03O.OOE+OO
0 10 20 30 40 50 60 70
Time (s)
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Methodl
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-30 35.5-36.0
DarelTimesamped:NA
Depth:35.5-36.0
Remolded or Initial
Sample Properties
Final (Post Test)
Sample Properties Test and Sample Conditions
Initial Mass (g):170.24
Diameter (em):5.381
Length (em):3.775
Area (em2):22.74
Volume (em3):85.85
Dry Density(glem'):1.98
DryDensity (pef):123.45
Water Conlent (%,gig):0.3
Water Content (%,vol):0.5
Porosity (%,vol):25.4
Saturation (%):2.2
Saturated Mass (g):186.53
Dry Mass (g):169.77
Diameter (em):5.381
Length (em):3.775
Area (em 2):22.74
Volume (em3):85.85
Dry Density (g/cm 3):1.98
Dry Density(pef):123.45
Water Content (%,g/g):9.9
Water Content (%,VOl):19.5
Porosity (%,vol):25.4
Saturation (%y:76.9
Permeant tiquid used:Water
Sample Preparation:0 tn situ sample,extrudedoRemoldedSample
Number ofLifts:NA
Split:NA
Percent Coarse Material (%):NA
Particle Denslty(glem3):2.65 0 Assumed D Measured
Cellpressure (PSI):32.0
Influent pressure (PSI):30.0
Effluent pressure (PSI):30.0
Panel Used:D A 0 B Dc
Reading:0 Annulus 0 PIpette
B-Value (%saluration)prior to test>:0.95
DatefTime:3/20/07 1510
..Per ASTM 05084 percent saturation is ensured (B·value ~95%)prior to testing,as post test saturation values maybe exaggerated orskewed during depressurizing and sample removal.
Laboratoryanalysis by:D.O'Dowd
Data entered by:D.O'Dowd
Checked by:J.Hines
Daniel B.Stephens &Associates,Iuc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-30 35.5-36.0
DarelT;mesampre~NA
Depth:35.5-36.0
Date Time
Temp
ee)
Influent
Pipette
Reading
Effluent
Pipette
Reading
Gradient Average Elapsed
(IIH/IIL)Flow (em')Time (s)
Ratio
(outflow to
inflow)
Change in
Head (Not to
exceed 25%,)
ksat Toe ksat Corrected
(em/st (em/s)
Test #1:
20-Mar-07
20-Mar-07
Test #2:
20-Mar-07
20-Mar-07
Test #3:
20-Mar-07
20-Mar-07
Test #4:
20-Mar-07
20-Mar-07
14:14:19 24.0 15.70 18.60 0.89
14:14:32 24.0 15.90 18.40 0.76
14:14:32 24.0 15.90 18.40 0.76
14:14:45 24.0 16.10 18.20 0.64
14:14:45 24.0 16.10 18.20 0.64
14:15:02 24.0 16.30 18.00 0.52
14:15:02 24.0 16.30 18.00 0.52
14:15:24 24.0 16.50 17.80 0040
0.17
0.17
0.17
0.17
13
13
17
22
1.00
1.00
1.00
1.00
14%
16%
19%
24%
8.21E-04
9.64E-04
8.93E-04
8.76E-04
7.47E-04
8.77E-04
8.13E-04
7.97E-04
Average Ksat (em/see):
Calculated Gravet Corrected Average Ksat (em/sec):
8.08E-04
Ksat (-25%)(em/s):6.06E-04
Ksat (+25%)(em/s):1.01 E-03
ASTM Required Range (+/-25%)
60 70503040
Time(s)
10 20
1.10E-03 ...,,-------------l
1.00E-{)3 -r---------------------------f~~~__I
Q.8.00E-04.•'--1
1i;7.00E-04 ~---.---''----------.-------------.----------~6.00E-04 :
5.00E-04 --------1
4.00E-04 +-~--~_--~---~---...,_---~--~-...J-I
o
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-30 44.0-44.5
Daterrime sampled:NA
Depth:44.0-44.5
Remolded orInitial
Sample Properties
Final (PostTest)
Sample Properties Test and Sample Conditions
Initial Mass (g):197.08
Diameter (em):5.361
Length (em):3.849
Area (em 2):22.57
Volume (em'):86.88
DryDensity (glem'):2.23
Dry Density (pef):139.23
Water Content (%,gig):1.7
Water Content (%,vOl):3.8
Porosity (%,vol):15.8
Saturation (%):24.1
Saturated Mass (g):214.34
Dry Mass (g):193.77
Diameter (em):5.361
Length (em):3.849
Area (em'):22.57
Volume (em'):85.88
Dry Density (glcm'):2.23
Dry Density (pef):139.23
Water Content (%,gig):10.6
Water Content (%,vol):23.7
Porosity (%,vo/):15.8
Saturation (%)-:149.5
PermeantJiquid used:Water
Sample Preparation;0 In Situ sample,extrudedoRemoldedSample
Number ofLifts:NA
Split:NA
Percent Coarse Material (%):NA
Particle Densily(glem 3):2.65 []Assumed D Measured
Cell pressure (PSI):32.0
Influent pressure (PSI):30.2
Effluent pressure (PSI):30.0
Panel Used:DA DB []C
Reading:D Annufus 0 Pipette
B-Value (%saturation)prior to test":0.95
DatefTime:3120107 1505
•Per ASTM 05084 percent saturation 1s ensured (B-Value ~.95%)prior to testing,as post test saturation values may be exaggeratE~or skewed during depressurizing and sample removal.
Laboratoryanalysis by:D.O'Dowd
Data entered by:D.O'Dowd
Checked by:J.Hines
Daniel B.Stephens &Associates,Inc.
Saturated Hydraulic Conductivity
Flexible Wall Falling Head-Rising Tail Method
Job name:MWH AMERICAS,INC.
Job number:LB07.0048.00
Sample number:MW-30 44.0-44.5
DarelTimesampre~NA
Depth:44.0-44.5
Influent Effluent Ratio Change in
Temp Pipette Pipette Gradient Average Eiapsed (outflow to Head (Not to ksat Toe ksat Corrected
Date Time (OC)Reading Reading (t.H/t.L)Flow (em')Time (s)inflow)exceed 25%)(em/s)(em/s)
Test#1:
20-Mar-07 14:23:21 .24.2 1.20 19.60 9.18 0.30 197 1.00 2%8.68E-06 7.86E-0620-Mar-07 14:26:38 24.2 1.55 19.25 8.97
Test #2:
20-Mar-07 14:26:38 24.2 1.55 19.25 8.97 0.39 237 1.00 3%9.53E-06 8.63E-0620-Mar-07 14:30:35 24.2 2.00 18.80 8.70
Test #3:
20-Mar-07 .14:30:35 24.2 2.00 18.80 8.70 0.22 146 1.00 2%8.80E-06 7.97E-0620-Mar-07 14:33:01 24.2 2.25 18.55 8.55
Test #4:
20-Mar-07 14:33:01 24.2 2.25 18.55 8.55 0.35 230 1.00 3%9.15E-06 8.28E-0620-Mar-07 14:36:51 24.2 2.65 18.15 8.31
Average Ksat (em/sec):
Calculated Grave/Corrected Average Ksat (em/sec):
8.19E-06
-~~~:~:1------~~---~---------------.------------------
~9.00E-06 ------..
::-8.00E-06 -.-.__.I
~7.00E-06
6.00E-06 t~-======~"=========~-~-=========j=r'
5.00E-06 -""-
I"150 250 350 450 550 650 750 850
.Time (5)
ASTM ReqUired Range (+/.25%)
Ksat (-25%)(em/s):6.14E-06
Ksat (+25%)(em/sl:1.02E-05
Moisture Retention
Characteristics
Daniel B.Stephens &Associates,Inc.
Summary of Moisture Characteristics
of the Initial Drainage Curve
Sample Number
MW-2355.5-56.0
MW-2374.3-74.6
MW-2382.7-82.9
MW-23103.3-103.5
Pressure Head
(-em water)
o
13
35
100
510
15195
42832
851293
o
14
56
155
510
43851
851293
o
12
38
97
510
23557
851293
o
8
24
85
510
16827
32838
851293
Moisture Content
(%.em3/em 3)
18.2
17.7
17.6
15.8
8.5
3.2
2.1
0.3
12.3
12.3
12.2
11.9
11.7
4.9
1.6
16.3
15.3
15.3
14.9
9.6
3.4
0.3
20.4
19.3
19.2
14.0
6.8
3.3
2.5
0.6
Daniel B.Stephens &Associates,Inc.
Summary of Moisture Characteristics
of the Initial Drainage Curve (Continued)
Sample Number
MW-30 35.5-36.0
MW-30 44.0-44.5
MW-30 44.0-44.5 (Volume Adjusted)
Pressure Head
(-em water)
o
7
20
74
510
23251
35081
851293
o
35
101
197
510
23353
851293
o
35
101
197
510
23353
851293
Moisture Content
(%,cm3/cm3)
19.5
19.2
19.0
14.1
7.6
2.6
2.1
0.4
27.9
26.7
24.7
23.6
20.5
10.9
3.4
26.7
25.6
23.5
22.4
19.4
10.4
3.2
Daniel B.Stephens &Associates,Inc.
Summary of Calculated Unsaturated Hydraulic Properties
Oversize Corrected
a N er es er es
Sample Number (em·')(dimensionless)(%vol)(%vol)(%vol)(%vol)
MW-2355.5-56.0 0.0103 1.3860 0.00 18.38 NA NA
MW-2374.3-74.6 0.0003 1.3544 0.00 12.16 NA NA
MW-2382.7-82.9 0.0069 1.3362 0.00 16.01 NA NA
MW-23103.3-103.5 0.0287 1.3494 0.00 20.51 NA NA
MW-30 35.5-36.0 0.0266 1.3480 0.00 19.86 NA NA
MW-30 44.0-44.5 0.0074 1.2019 0.00 27.59 NA NA
MW-30 44.0-44.5 (Volume Adjusted)0.0081 1.2006 0.00 26.43 NA NA
~-=Oversize correction is unnecessary since coarse fraction <5%of composite mass
NA =Not analyzed
._------_._---_.._._---
baniel B.Stephens &Associates,Inc.
Moisture Retention Data
Hanging ColumnlPressure PlatelThermocQuple
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2355.5-56.0
Ring Number:NA
Depth:55.5-56.0
Diy wi.ofsample (g):171.46
Tare wt..ring (g):0.00
Tare wi.,screen &clamp (g):0.00
Sampie volume (em'):84.63
Moisture
Con/enlt
(%vol)
Weight"
(g)DatelTime
Saturated weight"at 0 em tension (g):186.87
Volume ofwaler'in saturated sample (em');15.41
Salurated moislure content (%vol):18.21
Sample bulk densily (g/em'):2.03
Matric
Potential
(-em water)
Hanging column:21-Mar-07/10:45
27-Mar-07/10:10
02-Apr-07 I 08:47
10-Apr-07/13:05
Pressure piaIe:1g-Apr-07 I 08:35
186.87
186.47
186.38
184.81
178.62
0.00
12.50
34.50
99.80
509.90
18.21
17.74
17.63
15.77
8.46
Comments:
..Weight including tares
t Assumed de~sjty of water Is 1.0 g/cmS
Laboratory analysis by:D.O'Dowd
Dala entered by:T.Bowekaty
Checkedby:J,Hines
Daniel B.Stephens &Associates,lllc.
Moisture Retention Data
Water Aetiyity MelerlRelaliye Humidity Box
Job Name:MWH AMERICAS,INC,
Job Number:LB07,0048,00
Sample Number:MW-2355.5-56.0
Ring Number:NA
Depth:55,5-56.0
Dry weight'of water activity meter sample (g):246.44
Tare weight,jar (g):199.21
Sample bulk density (9Icm'):2.03
DatefTime
Water ActivityMeter:16-Apr-07 i 11 :03
13-Apr-07/14:45
Weight'
(g)
247.19
246.94
Matric
Potential
(-em water)
15195.0
42831.6
Moisture
Content'
(%Yol)
3.22
2.14
Dry weight'ofrelative humidity boxsample (g):82.32
Tare weight (g):39.51
Sample bulk density (glcm'):2.03
0.32
Moisture
Content'
(%Yol)
851293
Matric
Potential
(-em water)
82.39
Weight'
(g)DatefTime
Relative humidity box:21-Mar-07/12:00____--.",-,-,---'.:c..:..;;.__c..:..;;.::.;:c:,__-,-=--
Comments:
*Weight including tares
t Assumed density of water is 1.0 g/cm3
Laboratory analysis by:C.KrousiD.O'Dowd
Data entered by:T.Bowekaty
Checked by:J,Hines
Daniel B.Stephens &Associates,Inc.
Water Retention Data Points
Sample Number:MW-2355.5-56.0
1.E+06 :r.-~~~~"--
1.E+05 ; .·········_--·-t"..·__·------.
•
•
1.E+04 ................:--_._-_._-_.__:-.
~1.E+03
CI>
J:
~
::ltJ)e
11.
•Hanging column
...Pressure plate
•Thermocouple
•Water activity meter
XRh box........................;,.......................•...............................'--------------'
...
1.E+02 c ,.
III
III1.E+01 ;..-----.-"..,·····..········..·;·····--------------·----f·------·--··-.
6050203040
Moisture Content (%,cm3/cm3)
10
1.E+OO .f-.-~.-~~;-~~~.._r~~~~_i_~~~~~r-~~~~;-~~~.,.--I
o
Daniel B.Stephens &Associates,fllc.
Predicted Water Retention Curve and Data Points
Sample Number:MW2355.5-56.0
1.E+06o+------...,------,------,------,------,-----
1.E+05 ,..:;.
............................
...........;.................~...
•Hanging column
...Pressure plate
•Thermocouple
•Water activity meter
X Rh box
--Predicted curve.--~~"1'~.
.................~~~.
........................;.
..1.E+01 ,;~~.
1.E+04
-.:-.,.....<Il;;:
E
0•~
"0 1.E+03 .<Il.,
::J:
~:>tiltil~0-
1.E+02
601020304050
Moisture Content (%,cm3/cm3)
1.E+00 +-~~"""''''''''...,...i-~'-'--.~--+--,-,-...,..._-1
o
Daniel B.Stephens &Associates,lltc.
Plot of Relative Hydraulic Conductivity vs Moisture Content
Sample Number:MW-2355.5-56.0
1.E+00 ~--------......--,--,-~
1.E-01 +i i ;.
1.E-02 ......--_:_--..--------__-~----_.-..._~.._---_._--_.._-_.._--_.;--_.._--_..-.__.-.
1.E-06 +.
·····i-·······················;··..········------·-----
._-_::.. .
...___-_:__~--.-._.----,--__._.-
....___._~.-_.__,.
-'..-'_---,_----~----___.._._-~_!-.~.---_ .
___________..:.__,.1._1.E-03
1.E-04
1.E-05
1.E-0?...········r··~_-__~.
1.E-08 ;.:i·~.','"...~__~_.----__;..__-_..
6050203040
Moisture Content (%,cm3/cm3j
10
1.E-09 +-'\-~~~~~~~........;~~~~.-j--,~~~-+~~~~-r-~.~~~-j
o
Danie!B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Moisture Content
Sample Number:MW-2355.5-56.0
1.E+00 ,-----,.--------,---.----,--
1.E-01 ........................;::···..·.f························t·········.
1.E·02 ,:
1.E-03 ~,:;~.
1.E-0?.
1.E-05 :,:;-'--.
.:.--~,.
..........;j i..
.~.._~··..·········i··········.
.._~i .
............,~~.
.;..
......................................................................::;.
1.E·04 ..
1.E-05 ..
l.E-09
1.E-08
1.E-10 ....
1.E·11 :,..
5050203040
Moisture Content (%,cm3/cm3)
10
1.E-12 +-,L..,~~-i-~_~_-i-_~~~---,-_.•.-~,~~-;-~;-~~~---j
o
Danlel B.Stephens &Associates,fIle.
Plot of Relative Hydraulic Conductivity vs Pressure Head
Sample Number:MW-2355.5-56.0
i.E+OO j-=i'====;=:=====--~------i---r---i--l
i.E-Oi ···············r·····i ~·;;:: :.
.....!J.t .
••••••••••••••••••••••••j ••••••••••••••••~•••. .. .
.......~·~····--·········i···········..··1···-~-~..
...............:~~.
···············i······;;.......~,i···········..···:················:·········
...............;~:~;~~~_.
1.E-02
.?:'i.E-03'S;
~;;,
"0c:8 1.E-04
.!:1"5l:!-g,i.E-Q5J:
~~
~i.E-06
. .. ............................~:.
i.E-O?--
i.E-OB
.;....._;.,,.
........~~.
......:.
1.E+061.E+04 1.E+051.E+OO i.E+01 1.E+02 1.E+03
Pressure Head (-em water)
1.E-011.E-02
1.E-09 +-~~n-~~.,;-~~.,;-~~.,;-~_~..;.."_~.~.~"';".,~~,-.m-~~rcni-~.~=i
1.E-Q3
Dfilliel B.Stephens &Associates,file.
Plot of Hydraulic Conductivity vs Pressure Head
Sample Number:MW-2355.5-56.0
1.E+OO ~------c-
1.E-01 -..-..,-i..-.._._--.--+-+--,-..-..-......--;f.--------.· .· .
1_E-02 - -..••~•••....J_-1••.•--..······,·-·----··-··---·:·-----..---····-f··--·..-·------
1.E-03 ..-....._....._--;..-....-..-.---,_..._'....._-_._----_.........;----.-.._..;-.-_.._----_:__.._.
..1.E-O?---i---------..----i·----.---.-----------------,-------------"'-..----..-----.,-.-------..-,..--..---i----·---------.
...-__--.._._----_..~-_~-.;---------~-----_._-_~--.-.._-------_:-----------_._-:;
1.E-OB ---------..------------------..-----"'-'-'-"--'-..-._._--------_..._--_._._--.---· .
· .·,,.,.,'-.....;-.•-••••-......~••••••••••••••~-.--.----.----f·..••..••..--..+-····..···-----
.._.._;-..~-------__--:-.-_.---_._:------------_~-.,----------_._.-~-----_.__-· .·.
1.E-04 -
1.E-05 -..........-·.._i....
1.E-06 -+-i ---+
1.E-09 - ----.........,--..--..-------;---..-....-----,------------ --,----..-.-----.-.------..----........-...----..·c....--··-------c-'--.....--.--.
1.E-10 ...;.._~_._._.._---,._-_._.;_._..-· .-.--...,-..-----·-··-t--·-··-..--..·-t-···---·---····
1.E-11 ---------------,----------.-------------------..----------....---------------.----------------,-----------------------------,---------------
1.E-12-
1.E-03 1.E-02 1.E-01 1.E+OO 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
Pressure Head (-em water)
,~~r --....-=----,---,------------------Daniel B.Stepllells &Associates,Inc.
Moisture Retention Data
Hanging Column/Pressure PlatelThermocouple
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2374.3-74.6
Ring Number:NA
Depth:74.3-74.6
Drywt.ofsample (g):161.11
Tare wt.,ring (g):0.00
Tare wt.,screen &clamp (g):0.00
Sample volume (em'):69.19
Hanging column:
Saturated weight'at 0 em tension (g):169.61
Volume o/water t in saturated sample (em'):8.50
Saturated moisture content (%voi):12.29
Sample bulk density (glcm'):2.33
Matric Moisture
Weight"Potential Content'
DatelTime (g)(-em water)(%vol)
21-Mar-07/10:45 169.61 0.00 12.29
27-Mar-07/10:20 169.60 14.10 12.27
02-Apr-D7/08:50 169.58 56.40 12.24
10-Apr-07/13:40 169.35 155.00 11.91
Pressure plate:...."1"9..:.-A",p",r,.,-0"7,.,1,.,0"8",:3",0,-...."1",69",.",2,,,3__,,,,5,,,0,,,9,,,.9,,0__,-1,.,1",.7c::4,-_
Comments:
...Weight including tares
t Assumed density of water is 1.0 g/cm3
Laboratory analysis by:D.O'Dowd
Data entered by:T.Bowekaly
Checked by:J.Hines
~ii!~~~'-DaniellJ.Stephens &Associates,lllc.
Moisture Retention Data
Water Activity Meter/Relative Humidity Box
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2374.3-74.6
Ring Number:NA
Depth:74.3-74.6
Dry weight·ofwater activity meter sample (g):246.06
Tare welght,jar (g):197.61
Sample bulk density (g/cm'):2.33
DatelTime
Water Activity Meter:13-Apr-07 i 16:14
Weight'
(g)
247.08
Matric
Potential
(-em water)
43851.4
Moisture
Contentr
(%vol)
4.90
Dry weight'ofrelative humidity box sample (g):94.13
Tare weight (g):41.67
Sample bulk density (g/cm'):2.33
MatrJc Moisture
Weight'Potential Contentr
DatefTime (g)(-em water)(%vol)
Relative humidity box:...::;2"'1-"'M:.::a::.:r...:-O,,7...:/_1:.::2:.:::0,,0......::......::9:.::4.:..4:.::9......::_-=8.:.5...:12::;9:.:3......::__1:.:..6::0,-_
Comments:
...Weight including tares
t Assumed density of water is 1.0 g/cm3
Laboratoryanalys;s by:C.Krous/D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Daniel B.Stephens &Associates,Inc.
Water Retention Data Points
Sample Number:MW-2374.3-74.6
1.E+06 x
1.E+05 .......................•.....
.-..-.-..-.-._...-------------.--------------_._---_.-.,,
..-.---.--------------~------.--.--.--.-~.-..-.-··--·············1······-··-·-------------1---·----
1.E+04
-.:-
.$l..3'
E0•~
"0 1.E+03..CIl:I:
CIl~:>
UlUl~a.
1.E+02
...
III
..~.-..__._-_._--------..~_._------.._--------;__--_..--
•Hanging column
...Pressure plate
•Thermocouple
•Water activity meter
XRh box:----'
III
"I
,--,.--
..
1.E+01 ::.
1.E+OO
o 10 20 30 40
Moisture Content (%,cm3/cm3j
50 60
DaIJiel B.Stephens &Associates,Inc.
Predicted Water Retention Curve and Data Points
Sample Number:MW-2374.3-74.6
1.E+06 .,.,b-----,------,----------------.--,-----,
'.j __.
•Hanging column
...Pressure plate
•Thermocouple
•Water activity meter
X Rh box
--Predicted curve
. . ...._.__~..--__._-_..~;.
.~__.._~_,_.
...;;,,.
1.E+05 ,'+j .
1.E+04·
1.E+02 c·..·..
16 1.E+03
C>:I:
~;:JViVi~n.
1.E+01 ....···;···..0 ·•,···..•..
10
1.E+00 +-"i-
o 20 30 40 50
Moisture Content (%,cm3/cm3)
60
---------_._-_.._.•.••...._------
Daniel B.Stephens &Associates,Inc.'
Plot ofRelative Hydraulic Conductivity vs Moisture Content
Sample Number:MW-2374.3-74.6
1.E+00 r------,--,-----,-----
1.E-06 --..
l.E-01
1.E-02 ..
1.E-03 .
1.E-04 .
1.E-05 ..,..
..........:···_,---·------·--·--········f ,_.
.-__.~_.-.----_-~--_.----------.--_.--~-------._-------.
.---__---_'-----------_--:"-'-''''._--:_--
._-_._------,"_-------------(;_-_._------_...•....._-.
...--_._-_.__.:__._-------__---,---_--_~__.--_-,_.._.
·..·..· . ......:_.._ _;_';".
1.E-07 ..,,,,i..".
1.E·08 ,..:-.-:-,.
6050203040
Moisture Content (%,cm3/cm3)
10
.1.E-09 +-'~~~~;-~~~--;~~.
o
Daniel B.Stephens &Associates,lltc.
Plot of Hydraulic Conductivity vs Moisture Content
Sample Number:MW-2374.3-74.6
i.E+OO ,-----,-----.---,-------,------,------,-------,
1.E-Oi ---j---------------!.----------------------.:---._------.j ---.------i..-----------_-
i.E-02 ,,.L +;.
1.E-03 _ -.-------..~_---------------""..-:-.""'--"--~---_.-------.--_..;..--------------.---"._-..------.--
1.E-OB _.
i.E-OS··············C·:.._1.:!.!.
.....--_--___._------_.--..--.-._-_._--_-.:_--:_------.
...•.--_.;.------ ---- ._. _...----.!_..••.. -.•••.•.~...•••....."'".-••....
.....,~~__..~~.
... .---------;_-------_.._;.
i.E-04
1.E-06 ..
1.E-07 ..
i.E-09 ;;;;.
::
i.E-i0 ,;,,--f..
i.E-1i .................;;,~;.
6050203040
Moisture Content (%,cm'/cm3)
10
1.E-i2 +-+-~~~;........~~~-,...~~~~.....;-~~~~-i-~~~~+--~~~,.......j
o
~~~i01t~Da1Jiel B.Stephens &Associates,Inc.
Plot of Relative Hydraulic Conductivity vs Pressure Head
Sample Number:MW-2374.3-74,6
1.E+OO r~=i====;====;=======i--T---!--:--I
1.E-01 ,._,-_--;._:: _!.".."------_.
1.E-02 .......................-..-.-.~..._....--.....~...-;"""-.-""---;..-._---~-.._----..~_-_..
1.E-oe ;;,.:..:..,~,
...__.-..-;~~+;~~_.
..--.---.------~.:--·__···+-_·······_·_··-i..·_·_·_·······l __~_~_.._-_.._-
....__,1",;;_.._:.
........._--_..:.__.:----.:._--_..__.._---.-----.---------.---.-.-.------..-.
...............;~:·_····__···~·······_·······1···············1······_········r·--············~·······
1.E-03
1.E-04
1.E-OS
1.E-06
1.E-O?
1.E+061.E+OS1.E+041.E+OO 1.E+01 l.E+02 1.E+03
Pressure Head (-em water)
1.E-011.E-02
1.E-09~-~~~",.;."~~~";-~~~,,ni,,'~-.-n-n-or~~~,,;-~~,ni,,'c-~~,~'m"i-'~~IT"m",;-'~~_-rrmI
l.E-03
Daniel B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Pressure Head
Sample Number:MW-23 74.3-74.6
1.E+OO r------,------,-
1.E-01 ;:---,..--------:----------------c---------_·----c--·-------·----;-----.--_.-._--
1.E-02 ,,.----.-_.-------'.-..-_-:----~.----..-..-----~-_.----_.-.----;_.--.--_.-_.---
1.E-03 --;-------_._---_.;.-· . . ..___._.__.~_-..-_.._.__-__--_._-_-._--.-· ...· . .. ...
1.E-06 ,,,..
1.E-O?;;+;,;,;.
1.E-08 ,'.
._._-----.-.
...-----_._----_.___.. ..
.j.___..J.J..__~._.....~..._~..__. :__. . _
::
__"_._-·1__·--•.•••--.-;--+-----------.-----.
1.E-04 .
1.E-05
1.E-09 ,;;,:;;·r ·..
1.E-10 ;;..._.:.._--_._)._-_._--------_.~.-_._--------_.;._._._---------.___.
1.E-11 :j............L ;~:i .,j .
1.E+OO 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
Pressure Head (-cm water)
1.E-12 ...........,.-,,--rrn'I~TTr't-~~IT"',;..,~~~,,ni,,~~~IT"';'"~~,,..,.,..,-rr,...................,...-,--"'r~·~.,.\~..,j
1.E-03 1.E-02 1.E-01
Dalliel B.Stephens &Associates,inc.
Moisture Retention Data
Hanging Column/Pressure Platerrhermoeouple
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2382.7-82.9
Ring Number:NA
Depth:82.7-82,9
Drywt.ofsample (g):151.98
Tare wt.,ring (g):0.00
Tare wt.,screen &clamp (g):0.00
Sample volume (em'):72.35
Hanging cotumn:
Saturated weight'at0 em tension (g);163.80
Volume ofwalert in saturated sample (em'):11.82
Saturated moisture content (%vol):16.34
Sample bulk density (g/em'):2.10
Matrie Moisture
Weight'Potential Contentt
Datemme (g)(-em water)(%vol)
19-Mar-07/15:30 163.80 0.00 16.34
25-Mar-07 115;00 163.08 11.80 15.34
31-Mar-07/08:15 163.02 38.00 15.26
10-Apr-07/13:10 162.73 96.50 14.86
Pressure piate:-c1"'9"'-A""p"'r"'-0,,7"'/""0"'8e-:4"'O'------'1c:.58"'."'9c:.5__""5"'0"'9"'.9"'0'----__"'9"'.6"'3__
Comments:
..Weight including tares
t Assumed density of water is 1.0 g/cm3
Laboratory analysis by;D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Dalliel B.Stephells &Associates,Inc.
Moisture Retention Data
Water Activity Meter/Relative Humidity Box
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-2382.7-82.9
Ring Number:NA
Depth:82.7-82.9
Dry weight'ofwater activitymeter sample (g):240.86
Tare weight,jar (g):197.73
Sample bulk density (gfcm3):2.10
Matric Moisture
Weight'Potential Contentt
OatefTime (g)(-em water)(%vol)
Water ActivityMeter:-,1",62·A",p,,-r-",0_,_7-'./-,1-'.1,,:1-"3__2=:4"-1"'.5"'6'---_~2=:3"'5"'5_'_7".4'____"3o:.4'_'1__
Dry weight'ofrelative humiditybox sample (g):64.98
Tare weight (9):41.87
Sample bulk density (glem3):2.10
0.35
Moisture
Contenlt
(%vol)
851293
Matric
Potential
(-em water)
65.02
Weight'
(g)OatefTime
Relative humiditybox:22-Mar-07/12:00-=-=-=-==.::.c'----=-=__::..;;..;.=.::.__=c=_____
Comments:
*Weight including tares
t Assumed density of water is 1.0 g/cm3
Laboratory analysis by:C.Kraus/D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
'~~~~~Daltie/B.Stephens &Associates,Inc.
Water Retention Data Points
Sample Number:MW-23 82.7-82.9
1.E+06 r------,-----....,--------,------,-------,---------,
1.E+05 ,...-;- -..----~.--_.---------··········f·_----.._..-----._-.".".".---_.."._.
•
1.E+04 ------------_.-_~.._.-.----_._-----_._--~-----.._-------:_---__-;.____-_-...
';:'
.l!l~
E1-og 1.E+03 ,,.
Ql
J:
f!
::Jtiltilf!
Q.
•Hanging column
•Pressure plate
•Thermocouple
•Water activity meter
.xHh box..··......···,+......·l--..-·c-----'
1.E+02 ~...
III
1.E+01 .._-_:;-------,-_..
6050203040
Moisture Content (%,cm3icm3)
10
1.E+OO +-~~~~-i--~~'II ......-...-...-i-·-·,-..,--,....---r-·4;--~~~~--i-_~~_--I
o
5-.i!~~~'"Daniel B.Stephens &Associates,Inc.
Predicted Water Retention Curve and Data Points
Sample Number:MW-2382.7-82.9
1.E+05 yJ-----c--------,------,----
1.E+05 .
::
................,:················T······················
,,,,,,,,,,,,....._.-..--.-..'-'"'------.~.----------.---..--,-------'-'r-
1.E+04 _
'C'(JJ-ttl;:
E"•~
"tl 1.E+03ttl(JJ:x:
(JJ..::J
'"'"(JJ..0.
1,E+02
..._.--._-----~_..------..----..---_._.~,.---_--.--------~--.----_.--_.
•Hanging column
...Pressure plate
•Thermocouple
•Water activity meter
X Rh box
--Predicted curve
1.E+01 III....._-----_._-.__......•...__-.-;-----_.__._.._._~--.._._-_-._..-:--_-.
5050203040
Moisture Content (%.em3/em3)
10
1.E+00 +--~~~-i-~~-lI-~-+-~-__-+-~,~_·--i-~,~~~-+~.-~~...j
o
Daniel B.Stephells &Associates,Inc.
Plot of Relative Hydraulic Conductivity vs Moisture Content
Sample Number:MW-23 82.7-82.9
1.E+OO ,,-----c--c-r---:------,------
1.E-06 ,,.
..............._----_-_:.._--__.
...:_-____~---_._----_.-.
............__~_._.__.----_._~.__..__._---.-_._:_-_.--__-_-:,.,
....--------------l -------------L -------.j ---..--.----;------.--..--;-----.-------.
1.E-Oi .
i.E-03 .
1.E-02
i.E-05
1.E-04 ,,.........;,,.
i.E-O?,················,·······················r·············;,,.
i.E-DB ,:..............;+....__..__;..-__-.
60~~~~
Moisture Content (%,cm3/cm3)
10
1.E-09 +-+--i--r-'-i-_._,......,......._~.~_r_~__-I
o
Daniel B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Moisture Content
Sample Number:MW-23 82.7-82.9
1.E+00 T·------,-----,.------,-----,.------,------,
1.E-01 ....:-....-..-----:------------------.--.--,-----..-----·--·-----··f·-··-----····-··········
1.E-02 ,~;..·------------·------·1-·-----·-·-··-·---
1.E-03 ,,'-.
i.E-O?------_.-.---.-.--:---.--..--..----~-.-.----.-.--.~--.-:-------.---.-.---.--.-----.----.-.--
..-----.---.---------....••-.-••••.•.•-••--•.••~....:...-••-.-••-••.----~--••-•••.•••-.--------..j...--....-.---.-..--··f·-··..-···-····-·
1.E-Oa ,.._-_.-._.__..__._.._-_._--------_._---. .
·---i-··------····--------·--,------··-·-··..···----..
.....__._--------._---_._---_..----_.__._-__.._._.._.._.__._._.-----.._.___-.._._--_.-._.__-.-
-:----.----._---_._._-----:--_._-._-------._.....--:._---_.-----
l.E-05
1.E-04 ..
1.E-06 ..
1.E·09
1.E-10 .
1.E-11
----------_._---~--.-_--_.._..~.--_---_.._~.._-------_._..__-..--_._------------.-------.-.
.-.:-...-.....-...--_....-.,----------_.--....--...,_...
,.......,...............,.........._.....,.._._...._.....
6050203040
Moisture Content (%,cm3/cm3)
10
1.E-12 +--,J-~~~+-~_~c---i~--,--,~-i-~-i-~
o
,~~~i!I~Daniel B.Stephe1ls &Associates,Inc.
Plot of Relative Hydraulic Conductivity vs Pressure Head
Sample Number:MW-2382.7-82.9
i.E+OO r==::;::::::::=====::::;:==---;---r----;----:---···----
i.E-01 --_..,-,----,--1",--_..__J _-._..J.__.._.__._--~----.---,--------..,.·...-..~_--_._------:-_----.-..
i.E-02 ._-----..._....~....._---------~-_...
1E-06 '.--..______......._:._...:....___1...._.L._.._
i.E-05 •-------......·.;.....-......---i--------....-..;..----..---....,.......--------;
·.·.._;--___:-_..
---:-._----~
........._;__;...---------.._,-.._--,
..-.--__._----------..___----..~____~.__.i.E-03
i.E-04 -..•...
i.E-07 ...----i----------..j --------:--..----.---;...,.;_------_.~..-_..;.
i.E-OS .-......__-~~.___~..-;1 l - .
i.E+06i.E+05i.E+04i.E+OO i.E+Oi i.E+02 i.E+03
Pressure Head (-cm water)
i.E-02 i.E-01
1.E-09 +-~~~,i----~'~'~l'nTI,.........,....~'~'l~.,;-"~~~.,,;--~~.-rn-nr-.......,--r..,-r ..-rrO'-----~~~.,;-,.~~~-\,;--~~.,.,.=J
i.E-03
Daniel B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Pressure Head
Sample Number:MW-23 82.7-82.9
1.E+OO ,,----,...---
1.E-01 ,,,;,,,.......:,.
1.E-02 '..'n........', , .. .
1.E--D3 ...............;:~,.--~~...;;.
1.E.05 ,nn..',n ,n ..n ,,n n n n .
1.E-O?;;,,,,,.
1.E-08·n __n.n ,n __.,n ..::.
::...':......•........j.•.•...........
...........:--j........•......
..........:..;-:-:..
1.E-04 r·:::-n..:::-.=±==.-c::...;,n.""....=...=...=n.L-=.n-.n
1.E-06 .n••n •••••-+
1.E-09 ;~.--.;:;.;:.
1.E-10 ,n.n..__n !..__-<--n........,..:;;..
1.E-11 .,~~.,.•..__;~--__~,''.
1.E+061.E+051.E+041.E+01 1.E+02 1.E+031.E+OOl.E--D11.E-02
1.E-12 +-~~'"""'~~T',m.;--,~~'~'T',~"'""-~~~'j"r--,-"r'..,...'.,.nT-....--.--.~ni-_~=,;-~c-h~~~·
1.E-03
Pressure Head (-em water)
Daniel B.Step hells &Associates,Inc.
Moisture Retention Data
Hanging Column/Pressure PlatelThermocouple
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-23103.3-103.S
Ring Number:NA
Depth:103.3-103.S
Dry wt.ofsampie (g):126.16
Tare wt.,ring (g):0.00
Tare wt.,screen &clamp (g):0.00
Sample volume (em'):68.67
Hanging column:
Saturated weight'at 0 em tension (g):140.16
Voiume of water'in saturated sample (em'):14.00
Saturated moisture content (%vol):20.39
Sample bulk density (g/em'):1.84
Matric Moisture
Weight'Potential Contentt
DatefTime (g)(-em water)(%vol)
19-Mar-07/15:30 140.16 0.00 20.39
25-Mar-07/15:02 139.41 7.60 19.30
31-Mar-07/08:15 139.36 23.50 19.22
10-Apr-07/13:15 135.79 85.00 14.02
Pressure plate:-,-1",9-:;;A"p"-r-",0"-7.!..1",0",8",:4",0,--,-13",0",.",83"-_-"S",09,,,.,,,9,,,O__---,6",.",80,,-_
Comments:
*Weight including tares
t Assumed density of water is 1.0 glcm3
Laboratoryanalysis by:D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Daniel B.Stephens &Associates,Inc.
Moisture Retention Data
Water Activity MeterlRelative Humidity Box
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-23103.3-103.5
Ring Number:NA
Depth:103.3-103.5
Dry weight*of water activity meter sample (g):259.47
Tare weight,jar (g):199.70
Sample bulk density (g/em3):1.84
Daten-ime
Water Activity Meter:13-Apr-07 116:56
12-Apr-07/16:29
Welght*
(g)
260.54
260.28
Matric
Potential
(-em water)
16826.7
32837.6
Moisture
Contentt
(%vol)
3.29
2.49
Dry weight*ofrelative humidity box sample (g):87.89
Tare weight (g):38.83
Sample bulk density (9/em3):1.84
Malric Moisture
Wei9ht*Potentiai Contentf
DatefTime (9)(-em water)(%vol)
Relative humidity box:-=2.:c3--'.M-'.a:;;.r--,0-'.7-'./...:1::;2:..;:0.:.0_-=88.:c':;;.0.:c6 8:;;.5:;;.·1:;;.2:;;.9.:.3__-"0:..;.6:..;3_
Comments:
*Weight including tares
t Assumed density of water is 1.0 g/cm3
Laboratory analysis by:C.Krous/D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
DaHiel B.Stephens &Associates~I/lc.
Water Retention Data Points
Sample Number:MW-23103.3-103.5
1.E+06 TX-,-----,-------,------,-
1.E+05 ++.....~~.
•
•
............................-:_ _ __.~_._-.
................._;.._ _:-__.
1.E+04
-;:-
Q)......;;:
E0~
"0 1.E+03..
Q);r
~
::l'"'"~0-
1.E+02
................--.-~--~·-··---············~·····-··················i········
II
•Hanging column
...Pressure pl~te
•Thermocouple
•Water activity meter
xRh box
1.E+01 ,.........-~.;_--.,--..--····-·i·······················r··-····-··..---········-
6050203040
Moisture Content (%,cm3icm3)
10
1.E+OO +-~~_~i--~-~~.i~---i--__-
o
Daniel B.Stephens &Associates,Inc.
Predicted Water Retention Curve and Data Points
Sample Number:MW-23103.3-103.5
1.E+06 :rJ.----
1.E+05 ~--:..-:....;.
•
1.E+04
•. .......................................-:~;--.
-.::-Q)-~
E
J..
-g 1.E+03
Q)
J:
~:l
l/)
l/)
~a.
1.E+02 ,,..
•Hanging column
4.Pressure plate
•Thermocouple
•Wataractivity meter
x Rh box
--Predicted curve...............~i'":-:::.-:::.
.,.
1.E+01 ..
6050203040
Moisture Content ('Yo,em 3/em3)
10
1.E+OO +-,·..·-i-i__~~-jllh r-+--+-__~
o
~~~~~Daniel B.Stephens &Associates,lltc.
Plot of Relative Hydraulic Conductivity vs Moisture Content
Sample Number:MW-23103.3-103.5
1.E+00 ,...-----,
-.-----_.__._---~._--._._.__------~----_._-------_"_._---.--._-_:..,,
1.E·01·,.
1.E-02·-
1.E-03
1,E-04 ,..
1.E-05 ..
1.E-Q5 ........
..---··;·······-----------------,-················------·i----;----.__.
......,L.....
.-;-__-_--,-----;------_._--_..
----.---.....-··~_···--------------------!----_·_----·-·······--··i --.,.------------------
1.E-07 c··..·..··,·· · ·..;·..· ··:.
1.E-08 :..,,,..:----.-----.---.••._---~----._----_j••••_--_•••_-----"!..--------
1.E·09
o 10 20 30 40
Moisture Content (%,cm3/cm3)
50 50
--.--------_._._-
Daniel B.Stephens &Associates,Illc.
Plot of Hydraulic Conductivity vs Moisture Content
Sample Number:MW-23103.3-103.5
i.E+OO
,.1.E-01 --_-:_-_:-_._-___.---.._,..~..__..__.__,.
i.E-02 :,,,,..
i.E-03 ...__~.-..__._._----___._.:_;.
i.E-05 ,,..
i.E-04 ..
i.E-06 +,:..
..._..~...._.
i.E-OS .
i.E-O?.
1.E-09 ..
i.E-i0
. ......__..__..~-_._-_.._..-,--___-
.......~
6050203040
Moisture Content (%,cm3tcm3)
10
:::~::+-+--...~,..~t~"__..._·_..·_..·;....:.._.._..·_·.._.._m_.."..::~_......_.......__.....;.,_..._.._..._.._..._.._..._.._......;..:_"_"-"_"'-"_'''-'''_''-1
o
Dalziel B.Stephens &Associates,Inc.
Plot of Relative Hydraulic Conductivity vs Pressure Head
Sample Number:MW-23103.3-103.5
i.E+OO J'~==T:::==;===T--'-'
i.E·Oi ;:,..·············i···············;···············:········'.
i.E·02 -···---······..j···-···-·-·····i···············~..·-·-··---~-.----..-..···i·············-·.;···········-···~·-··········---··~-.
i.E.06 ;,L .L.:1...
.....__..;.._-_;.._.__~__~__._..;__.{_~:._._-.
... .
···:····..······.·..i __._
;--.;-·i···..--..
---::.....:....
....._--~.._._.._.__..-.~._.__-. -;'-'.
i.E-03
i.E-05
1.E·04 ...............•.....
i.E·O?,:,;.···-·-·~_·_···-·-·-····f········_··-·-·j_··_---·.._~...._._~-
i.E·OB ,j ;::+~:;..
i.E+OO i.E+Oi i.E+02 1.E+03 i.E+04 i.E+05 i.E+06
Pressure Head (-em water)
i.E-Qii.E-02
1.E-09 +-~~~'~r··~n-"~~=",;..~~~,,,;,-~~In-ri-,-,.....,..,."".-,---r;,~m--'r-~=_i-~~...,.,j
i.E·03
,~~~~,rDafliel B.Stephens &Associates,Iflc.
Plot of Hydraulic Conductivity vs Pressure Head
Sample Number:MW-23 103.3-103.5
1.E+OO ,.------c------c--~--__:_--."Cc-----,c------;-----,----,
1.E-01 .._-_i·----i.--...-:.-------+-.--~--..---.-----.-~.-------------·1·--···..····
1.E-02 ,,+,,,;.
. .. . .1.E-03 ..,,-'.·t ·,··..·i ··
1.E-OB ,,·..·,·..·..·..c··..··:,,,..
1.E-06 ,;.
1.E-O?..
... .,__!---------------
.:_--_.._---:__._-_._~..__.__._._;.
....._._.._-~-__._----_._.;._;.
_.__-~..-.---_._._._._-:-_.___~-_-._--..~..--_-_._-..,..
.--~_....;..l.E-05 .
_1.E-04 -_"..;--.__.__.__;.
.!!!Et.>~
~>~:l"Cc:o()
,g
:lE"C~
1.E-09 :--,;;,+·+··..·..·i ·..
1,E-1 0 ---"!---_._.··i··,,·'-·~--__._.__.:----------------:---------------,-----.._.-
1.E-11 ,...............................
1.E-12 y......,.-rT,..,.nr---,--,.·,·nnr.........,.--,-y..,....,.n'1-~'--,....-I·nl'i I,r--y-..,.,·,..,T.;-~~~;--A~=,-~~=1
1.E-03 1.E-02 1.E-01 1.E+OO 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
Pressure Head (-em water)
Daniel B.Stephelts &Associates,fllc.
Moisture Retention Data
Hanging ColumnlPressure PJateTThermoeouple
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-30 35.5-36.0
Ring Number:NA
Depth:35.5'-36.0'
Drywt.ofsample (g):169.77
Tare wI.,ring (g):0.00
Tare wt.,screen &clamp (g):0.00
Sample volume (cm'):85.85
Hanging column:
Saturaled welght*at 0 cm tension (g):186.53
Volume ofwater ,in saturated sample (em'):16.76
Saturated moisture content (%Yol):19.52
Sample bulk density (g/em'):1.98
Matric MOisture
Weight*Potential Content!
Datemme (g)(-em waler)(%'Yol)
21-Mar-07/10:45 186.53 0.00 19.52
27-Mar-D7/10:05 186.25 6.50 19.20
02-Apr-07/08:45 186.06 19.80 18.98
10-Apr-07/12:04 181.85 73.50 14.07
Pressure plate:-,1""9",-A",p,,,r-",°0.:.7",/",0""8",:3,,,0,---,-1",76",.",32"",_-,5",0"9",.9""0 7,,,.,,,6,,3__
Comments:
,.Weight including tares
t Assumed densIty of water is 1.0 g/cm3
Laboratory analysis by:D.O'Dowd
Data entered by:T.Bowekaly
Checked by:J.I·jines
Daniel B.Stephens &Associates,fnc.
Moisture Retention Data
Water Activity Meter/Relative Humidity Box
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-30 35.5-36.0
Ring Number:NA
Depth:35.5'-36.0'
Dry weight*of water activity meter sample (g):272.00
Tare ....Ieight,jar (g):199.26
Sample bulk density (g/em'):1.98
Datemme
Water ActivityMeter:13-Apr-07 /09:56
12-Apr-07/16:53
Weight*
(g)
272.96
272.76
Matrle
Potential
(-em water)
23251.4
35081.1
Moisture
Contentt
(%vol)
2.61
2.07 .
Dry weight*ofre/atlve humidity box sample (g):57.87
Tare weight (g):38.35
Sample bulk density (g/em'):1.98
Matric Moisture
Wei9ht*Potential Contentt
Datemme (9J (-em water)(%vol)
Relative humidity box:-.-:::2-:.4--:.M-:.a::;r""-0:.;7""1_1c:2,,,,:0:.;0,--,5,,,,7c:.9-:.1__-=-85::;1:..:2:..:9c:3__-,0.;;.3:.;7_
Comments:
*Weight including tares
t Assumed density ofwater is 1.0 g/cm3
Laboratory analysis by:C.Kraus/D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Daniel B.Stephens &Associates,l"c.
Water Retention Data Points
Sample Number:MW-30 35.5-36.0
1.E+06 T.-;-----.,.------:-----.,-------.,.-------,-----,
1.E+05 ..._-_~__:_--~_-.__.......•..__-__.-"-"'--'-".
••
.._-_.__.~__.___.__-_.__.._-__._-__.-_.___---
1.E+04
-;:-.e<II:::
E(J
..!..-
-0 1.E+03<IICl>:I:
~::>IIIIII~a.
1.E+02
.......................~.._--------...~....._.----_.._--.:---_.__._.----_.._;.
•Hanging column
"Pressure plate
•Thermocouple
•Water activity meter
xRh box...............................~=:;-----'
II
1.E+01 .._.:"'__--.~..
6050203040
Moisture Content (%,cm3Jcm3)
1.E+00 +-i-~__-+~~~_--.;...---~-...;-~~~...,.......i
o 10
Daniel R.Stephens &Associates,Inc.
Predicted Water Retention Curve and Data Points
Sample Number:MW-30 35.5-36.0
1.E+06 rr------,-..-----.-.--c---~-~----_c----__,----...,
1.E+05 ;,..-:-~············r············--········
1.E+02 ;.
...~-..·~-·······-··-·-·········i
1.E+04
-g 1.E+03
(1)
J:
fI!
:l'"'"fI!a.
......._:--:_j __._.r-.Hanging column
..Pressure plate
•Thermocouple
•Water activity meter
X Rh box
--Predicted curve··········,·····················i·········~:
........_:_:-~_.
.;
1.E+01 .............__~~__~_-_._..
605010203040
Moisture Content (%,cm3/cm3)
1.E+00 j-~~~_;_~,~..-~+-~~~~-_i__~~~_i___~_1
o
~i;:~~~~Danicl B.Stephens &Assoclates,Inc.
Plot of Relative Hydraulic Conductivity vs Moisture Content
Sample Number:MW<1O 35.5-36.0
1.E+00
1.E-01 ......._-----.._------_.:.._----.-_._-.....------:-._-_....-----.
1.E-02 .
--------_.."_-------;-----_.
....-..-.---------_.--..~-_.-.-----__--_.:_-_-.-_---------------.---__-_..1.E-03
1.E-04 .;,,_ .
1.E-05
1.E-06 .
1.E-07 .--..-------+.------.--------~------.-_······1····.-.---;.--.---.-----~----_.._-_..
1.E-08 ,......__.:..__.._..;-------••.••--.-•••-----i -----------..,-_-.---
6050203040
Moisture Content (%,cm3icm3)
10
1.E-09 +-.,L-~~~·-I~~'~~-i-~~~~;-.,~~~---i--~~~~-i-~~~,..-j
o
,~~....--_..Daniel B.Stephefls &Associates,Inc.
Plot of Hydraulic Conductivity vs Moisture Content
Sample Number:MW-30 35.5-36.0
1.E+00
l.E-01 ............:__._---.----..-.~_..:.-..--i._-------..,-.-----..----.------
1.E-02 ....._._-_,_:---_.---------_.-_--~.._---_..----.
1.E-03 ...--_.._---__.._~..__._.._.---..__._~----___..__.._~..-------_.._---_:_---------;------___.
......_---_.:-..__:---_.;-------------..----'-':'"..--__--;..__.
_._-;.-..-.--------_.-_._..;-------.._.-_.-_.._._--
..............:__._------------_:___---_.-
..--~.-.-.------------.-~---..----·--:-------------·-····-····t·-··--·---·-·-----··--·-
-..-----_..-.:---.-._.-_.._----
1.E-04
1.E-05 ..
1.E-06
1.E-0?
1.E-08
1.E-09
1.E-10 ;,...__.•...j _-----_.._.._-----;-_._--.-_ _..,'-_..-----..___.._.
1.E~11 ..-.-.-----.--.-.-:.--.--...-.;._.._-.._---.....-.._--,.__.·-·--·-1·----....-...-.-......,.---....-..
6050203040
Moisture Content (%,cm3/cm3)
10
1.E-12 +---,L-,~~-i-~~~-~-i-­
o
Daniel B.Stephens &Associates,Inc.
Plot of Relative Hydraulic Conductivity vs Pressure Head
Sample Number:MW-30 35.5-36.0
1.E+OO r~=::;::========f--T--:---~-----
1.E-01 ,,,,:,,+.
1.E·02 .
1.E-06 ,'--c ,,.
. .1.E·05 .';.
.::;;...........:__:.---.
:::. . ..~..:_:..
.,...
1.E-03 .
1.E-04 -.......
1.E-O?...............;........
1.E·08 ,,;······i··i·c.......•.....:;••••••••........
1.E+OO 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
Pressure Head (-em water)
1.E-02 1.E-01
. ...1.E-09 -I-~~~,~,~=,.".;__~~,,;-~~~,r_~~=i-_~,~...i·.........,..-,-rTrr"·.,..,..,.......--..-"."'"
1.E-03
Daniel B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Pressure Head
Sample Number:MW-30 35.5-36.0
1.E+OO ~_...._-~~~--~-----~~~------~
1.E-01 __.__'_'~•••••___••_.••__•••••;•••••••••••••••1•••••••••••••••
1.E-02 ...;---__~.-..,!__.:._-.._--
..1.E~03 .._--- _..:.._········i··--_._~-..~-._---_._-----..:-"---._-------;.---._-_: "-i .•••.-..•..•...
1.E-06 .···············i···············,·····,,,,...............•..............................
1.E-07 ;.....,,.
.....__------._--_.__~---.--.-_..-----:-._-_._----_.._;-_._--_",:---------;---------------
.;__._-_;-_......;,.-----;
.........-..---,--------_~.._._--_.._~---.~--"--_~--__~-.-------------i -__..
...__.l.__.j_ -'-.-'1.E..Q4
1.E-05
1.E-08
1.E-09 ...........-_.-...~--------------~--_...-_._....,...-
1.E-10 ,·..············i···...;-----:_.._-:;-_-_--:---------._----;-----_._--_,_--_.._---_.
1.E-11 ---------_;_---_._---;-..~.
1.E+05 1.E+061.E+041.E+OO 1.E+01 1.E+02 1.E+03
Pressure Head (-em water)
1.E..Q11.E·02
1,E-12 -l-~~~;.....~~=-'.........,.....TTn---T-',·..,.OfT1___r..,..'....._rnTf-T ......'·~.,..,.,.,.I..........,.'~~_oi__.l,...~~n~~
1.E-03
,~~.,--,--,---------------------------
DOlliel B.Stephens &Associates,lllc.
Moisture Retention Data
Hanging Column/Pressure PlatefThermocouple
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-30 44.0-44.5
RingNumber:NA
Depth:44.0-44,5
Drywt.of sample (g):193.77
Tare wt.,ring (g):0.00
Tare wt.,screen &clamp (g):0.00
Sample volume (em3):86.88
27.90
26.71
24.75
23.57
20.46
Moisture
Contentt
(%vol)
0.00
34.50
100.50
197.00
509.90
218.01
216,98
215.27
214.25
211.55
Weight'
(g)DatefTime
Saturated weight*at 0 em tension (g):218.01
Volume ofwatert in saturated sample (em'):24.24
Saturated moisture content (%vol):27.90
Sample butkdensity (glcm3):2.23
Matric
Polential
(-em water)
Hanging column:30-Mar-07 /08:55
27-Mar-07/10:10
05-Apr-07/11 :40
11-Apr-07 I 07:50
Pressure plate:25-Apr-07/15:30
Comments:
*Weight including tares
t Assumed density of water is 1.0 glcm3
Laboratory analysis bY:D.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
Daniel B.Stephens &Ass()ciates,Inc.
Moisture Retention Data
Water Activity MeterlRelative Humidity Box
Job Name:MWH AMERICAS,INC.
Job Number:LB07.0048.00
Sample Number:MW-3044.0-44.5
Ring Number:NA
Depth:44.0-44.5
DiY weight'ofwater activity meter sample (g):249.86
Tare weight,jar (g):196.46
Sample bulk density (glcm');2.23
Matric Moisture
Weight'Potential Contentl
DatelTime (g)(-em water)(%vol)
Water Activity Meter:-,1",2-,--A-"p"-r--"0-,-7-,-1..:.1",5..:.:1-,-7_-,=-25",2~.4-,-8,,--_-,2,,,3,-,3o=5,,,3-,-.4,--__1..:.0".9,,-4-,---
Dry weight'ofrelative humidity box sample (g):90.08
Tare weight (g):38.03
Sample bulk density (g/em'):2.23
Matric Moisture
Weight'Potential Contentl
DatelTime (g)(-em water)(%vol)
Relative humidity box:--'=2.:..1-.:..Mc:a:::.r..:-0,,7..:1...:1c::2..::0;.:O'-.....:9c::0.:.:.8:..;7__-=8=.51.:.:2,,9c::3__-=3".3c::8,--
Comments:
...Weight including tares
t Assumed density Of water is 1.0 g/cm3
Laboratory analysis by:C.KrouslD.O'Dowd
Data entered by:T.Bowekaty
Checked by:J.Hines
,,~~~~~Daniel B.Stephens &Associates,Inc.
Water Retention Data Points
Sample Number:MW-30 44.0-44.5
1.E+06 0---;:,.----;-------....,------,------,-------,-------,X
1.E+05 ......................•......................,........................•:-;.
.----__--_-~-_--_..------_--..:..-.---..---__._._..~-_.__- .___----_-_--__-
,.........................c '<11•......••....•.•.......•.....••...,...••••....•.•......•••.,...••.•..........••.•..
1.E+04
-;:-
1!lIII::
E<.l-l-
""0 1.E+03III<I>:J:
~::>1/11/1~0-
1.E+02
..--_---_:--_----_--~_._--"'---'--.---_,-----__---_(
••
•Hanging column
..Pressure plate
•Thermocouple
•Water activity meter
XRh boxL.--'-'-~.....
•
1.E+01 ,,,------···---f..·---·----..
6050203040
Moisture Content (%,cm3/cm3)
10
1.E+OO +-~~_··.,__....,_...·1-·-1-,...___,__,..........,;-_~-,rl ••-..;-~~~~-;j ..........-.,.......---r_·~.....;.~__~~....j
o
Dalliel B.Step hells &Associates,JIlC.
Predicted Water Retention Curve and Data Points
Sample Number:MW-30 44.0-44.5
1.E+06 Y--,-;--r---c,------,-------X
1.E+05 ..................................~_~.
1.E+04
~....,-IV;:
E0•~
"0 1.E+03...,
:x:.,...
"tiltil.,...a.
1.E+02
.....................~~_.........•.........."'-..
•Hanging column
...Pressure plate
•Thermocouple
•Water activity meter
X Rh box
--Predicted curve
..._ _.._:.._:_.__..___~._.____.__~__.
1.E+01 ..............................•.......................· .· .· .· .
6050203040
Moisture Content (%,cm3/cm3)
10
1.E+00 +-~~~~--;-~~~~-r--~-...-+_~~~-+-~~~-~--;~~~~-i
o
Daniel B.Stephens &Associates,Inc.
Predicted Water Retention Curve and Data Points
Sample Number:MW·30 44.0-44.5 (Volume Adjusted)
1.E+06 ~--:-+X
1.E+05.
-,------,.----,--_._._-_..
·
..__._--_..__--:---_--_.__..••-•...>•.._.._-----_-(_•._.-.•_•.••.-._--_-
••
1.E+04 ..
-g 1.E+03
(J):x:e:JIIIIIIe0..
1.E+02 ,..
1.E+01 .
·...........__.._--.___.__-.....•.-_-------_.· .·.-cc;------,•Hanging column
...Pressure plate"
•Thermocouple
•Water activity meter
X Rh box
--Predicted curve.i·
.,. . ......--.--..+-.....--------.....-..-~.-....-..-.-..--....----r·-·..··-·-----..·-·-··
1.E+00
o 10 20 30 40
Moisture Content (%,cm3/cm3)
50 60
Daniel B.Stephens &Associ«les,Inc.
Plot of Relative Hydraulic Conductivity vs Moisture Content
Sample Number:MW-30 44.0-44.5
i.E+OO --,---_.•..-,------,-----.,------,
i.E-Oi ;,,:;.
1.E-02 -.-_-..-~..-_-.--------.----~-----_._---_.---------.~-._--_---_.---_-_-.------_.._-_---------.
i.E-06 c ,,.
i.E·04 ,.......................•........................;.
......................L ;._~__..._.__
...-~._.--_-
-,~._----_._-_._--.-.----......:._-
i.E·03 .
1.E·05 ,..
i.E-O?..
i.E·08 .-..1.---)1 ----..;-_._--.-----.---.----..,--------.-.--.
i.E·09 ...
o 10 20 30 40
Moisture Content (%,cmS/emS)
50 60
~~ii~~~r'Dalliel B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Moisture Content
Sample Number:MW-30 44.0-44.5
1.E+00 ,..------,--------,---------,----.
1.E-01 -_._ -..-."!"--.--------•••••••••••--;----------..---•••-----~_..--.._-_._-.........••l•...•...-.-------------~----_.-.---.----
..,.1.E-02 ';;,..
1.E-03 );L ..L............. .
1.E·05 ,,.
1.E-06 ,+..
·,·--···---···--·i··-------·--------------i----·..·---------.
-----;..-------------_.··---··;············----------·-i-----···--
-------,."'--"._-_.._-_~..-_.__._-----------_.__:._-_._.
._-_.._.~.--.----------------:_------_.:._----__-.._..~--_----._----_..-_......
1.E·04 .
1.E·07 ,.
1.E·OB .
1.E·09 .--_.~._-----------_.__.__{._._._-_._-__-.--.-._------------_-_.._---
1.E·10 -..._._-_...,....._.._-_.....-.---!-----"-'1 .---.-..-"---.
1.E·11 ..-_.:--._-._.-.--_.-..-_._--:_..__----_._~------------._-----._---~-._-_-;----_._._--_.---_.._---
50 60203040
Moisture Content (%,cm3/cm3)
10
1.E-12 +-~~~-i''-..,-~~~-+-~~~·~-·-;''I~~~~+-~~~-,~~~~-1
o
,~~~ifJ"D-a-ni'~'i B.Stephens &Associates,Inc.
Plot of Relative Hydraulic Conductivity vs Pressure Head
Sample Number:MW-30 44.0-44.5
1.E+OO -r""=,---,------,-----,-----,----,---.,.....----,-----,------,
1.E-01 '"..........\__.._.j --.L ~t .
1.E~02 -----.--.
..._..-~..--------------~_.._----_._.._-
.~---;.----
••••••__•__.~••••••••••••••,••••••••••••••h .":-----_..__._-
...__.::.__._-_:.--_-~-_.-..-..:.-._-_._--------
........:.....
.._-----_..:-_.:..-
.__~--_------;---------_.-~-_~-,
..;-._~..-_.-
1.E-Q3 ,....
,.::1.E~04 .···············i--:.
1,E-05 .........
1.E-06 ..
1.E-O?;;,i.........j ;.
1.E-OS
::;:1.E~09 ...........,....,.,nT-......,....,...-·'-rm.;..........,-.·.-rrnT--r,...,..,..,..";..:~~~"mji-~~'~"'.;-,~.~~m-_~~,;.L~.~"'""
1.E-03 1.E-02 1.E-01 1.E+OO 1.E+01 1.E+02 1,E+03 1.E+04 1.E+05 1.E+06
Pressure Head (-em water)
Dalliel B.Stephens &Associates,Inc.
Plot of Hydraulic Conductivity vs Pressure Head
Sample Number:MW-30 44.0-44.5
1.E+OO
1.E-01 __-_.._._._~_._-----_.._---~_---_._--_.~--._--_.-._~.._--_.._--_.-.-!----_.._-!--_•••••_._.-._;••••-------_••_'
1.E-02 ...-...._.....,..-._-_._.-...:.-...._.._.._-~.....-..:.....-.-..--.-.:-..---.....-.-..~.--.-·-···-··-·i-···-..--.-.....:..
1.E-03 ...___~--_._--..~-----__-_..~._.:---__-;-_-..-. .
1.E-04~o-
. ......----_:--__-:__.--~.-'-'".~_._---_...._-_.j"---_...._._....~----_....._.__.;._---_....._---:..._-
1.E·06 ·f ·;···:·..· ·..·;···
----.----------;---..-.-...--.-,---..---...----;--.---...---.--.:.----.-.-.--..--'-----..--....--~·----·-----···-t·----······--··!---·····
.-_.....-_.._--;---_..._--_....;--_.....-...-_._---_.._.....--.__._..-.....---_..._-....._-._~....-'--"_._..~---_.'--_._._._:..----_._._..-.
.. ..-·:-·-·-····-----··~··-·-·-·-··----t····----·····--i--...--.----...
---.----..--.•----.--·--··-i--········---·-:-·-··-·----····_.._---_._._.-.;._.._-.__.----.:------.._._.-
1.E-05
1.E·O?
1.E·08
1.E-09 ,i ,····..1 · ·1"'·;,,.
1.E·10 _._._..._.-_...,.-.....-.---_._;..._.__._-:.•••.•_...:•••__..._.•:•'_":''"__...c••__..._.-.,----_.
1.E-11 --..--------- --..--.---'---j-'-.--"-.---:---..---..-..--+- -..~--~-····-········-f---·.
1.E+02 1.E+03 1.E+04 1.E+05 l.E+061.E+OO 1.E+01l.E-011.E-02
1.E-12 +-~~=i~~n_.,.,..,..".....,._rrr,,.,,........,.-,....,_·r_rrni-~~,,.,;.~~=-oi-~~=,;....+~n_ni~~~nI
l.E-03
Pressure Head (-cm water)
Laboratory Tests
and Methods
Daniel B.Stephens &Associates,Inc.
Tests and Methods
Dry Bulk Density;
Moisture Content:
ASTM 04531;ASTM 06836
ASTM 02216;ASTM D6836
Calcuiated Porosity:ASTM 02435;Klute,A.1986.Porosity.Chp.18-2.1 ,pp.444-445,in A.Klute (ed.),
Methods of Soil Analysis,American Society ofAgronomy,Madison,WI
Saturated HydraUlic Conductivity:
Falling Head Rising Tail:ASTM 05084
(Flexible Wall)
Hanging Column Method:
Pressure Plate Method:
Water Potential (Dewpoint
Potentiometer)Method:
Relative Humidity (Box)
Method:
Moisture Retention
Characteristics &
Calculated Unsaturated
Hydraulic Conductivity:
ASTM 06836;Klute,A.1986.Porosity.Chp.26,In A.Klute (ed.),Methods of Soil Analysis,
American Society of Agronomy,Madison,WI
ASTM 06836;ASTM 02325
ASTM 06836;Rawlins,S.L.and G.S.Campbell,1986.Water Potential:Thermocouple
Psychrometry.Chp.24,pp.597-619,in A.Klute (ed.),Methods of Soil Analysis,Part 1.
American Society of Agronomy,Madison,WI.
Karathanasis &Hajek.1982.Quantilative Evaluation afWater Adsorption on Soil
Clays.SSA Journal 46:1321-1325;Campbell,G.and G.Gee.1986.Water Potential:
Miscellaneous Methods.Chp.25,pp.631-632,in A.Klute (ed.),Methods of Soil Analysis,
American Society ofAgronomy,Madison,WI
ASTM 06836;van Genuchten,M.T.1980.A closed-form equation for predicting the
hydraUlic conductivity of unsaturated soils.SSSAJ 44:892-898;van Genuchten,M.T.,F.J.
Leij,and S.R.Yates.1991.The RETC code for quantifying the hydraulic functions of
unsaturated soils.Robert S.Kerr.Environmental Research Laboratory,Office of Research
and Development,U.S.Environmental Prolection Agency,Ada,Oklahoma.
EPAl600/2091/065.December 1991
APPENDIXB
SPECIATION AND SURFACE-COMPLEXATION MODELING OF
TAILINGS POREWATER
APPENDIX B
SPECIATION AND SURFACE-COMPLEXATION MODELING 011 TAILINGS
PORI~WATER
PURPOSE
The purpose of this appcndix is to describe the methodology utilizcd in modeling the
speciation and adsorption of aqueous complexes to predict the fatc and transport of
dissolved uranium and other contaminants of concern (e.g.,arsenic,beryllium,cadmium,
etc.)through the vadose zone beneath the White Mesa Mill tailings-disposal facility.As
part of this study,a comparative analysis between different geochemical databases was
eompletcd in order to produce a dataset comprised of aqueous-complex formation and
adsorption coefficicnts based-on a state-of-thc-art understanding of uranium
geochcmistry and thcrmodynamies.The geochemical modeling was used to calculatc
distribution eoel1icients (Kd)betwecn infiltrating tailings porewater and the undcrlying
bedrock,thereby addressing requirements specificd in Part UI.II of thc Ground Watcr
Discharge Permit No.UGW370004.
BACKGROUND
Geochemistry of Uraninm
In groundwater considered to represent reducing or low Eh conditions,uranium in its +4
oxidation state (U(lV»as uranous ion (lJ"')and its aqueous complexes comprise the
dominant forms of uranium (Figure B-1).Uranium in its +6 oxidation state (U(VI))as
the uranyl ion (U02'2;U+6;U(VI»and its aqueous complexes predominatc under
oxidizing or high Eh conditions.Uranium in the mineral uraninite (U02 [crystalline])is
present mainly as U(lV),and is known to have a relatively low solubility.Consequently,
uraninite is considered to be insoluble under rcducing conditions and concentrations of
dissolved uranium will be correspondingly low.The solid green line on Figurc B-1
dcmarcatcs the solubility limit for uraninite at a concentration of I x 10.8 molar (M)or
approximately 2 micrograms pcr liter (JlglI).The solid green line represents Eh and pH
conditions for water in cquilibrium with uraninite at a concentration of 2 flgll.Thus,
B-1
water samples with pH values between 2 and 5.22 and Eh values lower than 0.174 Volts
will have concentrations lower than 2 ~lg/l.Increasing the Eh will increase the dissolved
uranium concentration.Under increasingly more oxidizing conditions the stability field
of uraninite will increase,but with a correspondingly greater dissolved concentration.
For example,Langmuir (1997,Figure 13.10)displays a diagram set at a concentration of
I x IO·5 M total uranium.In Langmuir's (1997)diagram,the stability of U02
(crystalline)has "moved up"to approximately 0.25 Volts,but so has the concentration of
uranium,which is now at a value of approximately 2 milligrams per liter (mg/l).In
general,uranyl-bearing minerals tend to have higher solubilities and therefore uranyl is
considered to be soluble or mobile in oxic groundwater environments.In that same
figure,Sehoepite (I3-U03'2IhO [crystalline])shows stability between pH values of
approximately 5 to 7 at a concentration of 1 x IO's M.
At pH values greater than approximately 5,uranyl forms strong complexes with
carbonate species.An example of tbe distribution of uranyl complexes is shown on
Figure B-2,which was constructed with the project-specific database described below.
For simplicity,the figure docs not include all ofthe aqueous complexes;it only shows the
dominant species.These aqueous complexes inHuenee the nature of the surlaee-
complexation reactions that are used to define adsorption reactions and the subsequent
estimation ofsorption distribution coeHieients (Kd's).
Generalized discussions regarding the geochemistry of additional solutes,including trace
metals present in the tailings porewaters,is summarized in the Revised Background
Groundwater Quality Report (INTERA,2(07),a partition coefficient document prepared
by the U.S.EPA (1999),and textbooks on aqueous geochemistry (Langmuir,1997).
Speciation of Aqueous Complexes
The distribution of elements among aqueous species and ionic states,and their proclivity
for complexation,has a significant effect on solution chemistry and contaminant-
transport mobility.The speciation of clements and f{lnnation of aqueous complexes is
governed by thermodynamic constraints,which can be determined with a series ofmass-
..~~.~~~~~~--~~~~.-~--~~--~-------
B-2
action and mass-balance equations solved simultaneously through the usc of a
geochemical-computer code (e.g.,Parkhurst and Appelo,1999).The code references a
databasc containing mass-action equations and aqueous-complex f(Hmation (stability)
constants.For example,the geochemical-computer code PHREEQC contains a suite of
thermodynamic databases that the user may select as part of the modeling excrcise.Two
of thc databases available with the PHREEQC-modeling package are identified as
watcq4f.dat and mintcqa.v4.dat.These particular databases include complexation
reactions for uranium species and other trace metals.Unforiunately,databases
distributed with the so!lware are seldom updated on a regular basis.As a result,the user
must update the database to reflect contemporary estimates of thermodynamic properties
for thc solutes of interest.
The results of the comparative analysis between geochemical databases for uranium are
tabulated in Table B-1.Potential sourccs of error identified include the use of antiquated
complex-formation constants and an incomplete dataset of uranium-aqueous species.
The f()!lowing uranium (VI)complexes identified in Grenthc et ai.(1992);Davis and
Curtis (2003);Gui!laumont et al.(2003)were not included in the wateq4f and minteqa.v4
databases:
•U02(OHh"q
•(U02hC03(OH),'
•(U02hCO,(OH)3 '
•(U02)11 (COJJ<,(OI-l)122-
•CaU02(COJ)/
•CaZU02(CO')3,,,q
•UOz(lhP04)(I-IJP04)'
•UOzSiO(OHh'
•U02(S04)3'"
•U02HAs04
-_.•..._--_.._-
B-3
•U02112As04'
• U02(l-bAs04)2
For this study,these aqueous species were added to the dataset ofuranyl complexes.
Although sitc-specific geochemical conditions will dictate uranium spceiation among its
complcxcs and ionic states,incorporation of a comprehensive thenl10dynamic database
will serve to minimize the effcct of excluding potentially salient specics.For cxample,
spcciation calculations presented in the work of Davis et ai.(2004)indicated that two
calcium-uranyl-carbonate species accounted ftlr 96.3 to 98.8%of dissolved uranium(VI).
Exclusion of these calcium-uranyl-carbonate complexes hom the thermodynamic
database could significantly increase the total amount of uranyl available to participate in
surface-complexation reactions.Therefore,because a greater proportion ofuranyl will be
stabilized in solution by the formation of uranyl-bearing aqueous complcxes,the amount
of uranyl available for surfilce complexation is lowcred,which will therefore lower the
total amount of uranium sorbed onto surfilees and ultimately lower the Ket•A complete
listing of uranium aqueous-eomplex-flllmation constants and reactions incorporated as
part of this study is included in Table B-1.
Adsorption of Aqueous Complexes
Chemical reactions between dissol ved constituents In groundwater (e.g.,metals and
radionuclides)and the aquifer matrix onen dictate spatiotemporal variations in
contaminant-plume transport and mobility in the subsurface by controlling the degree of
adsorption-desorption of aqueous complexes to surface assemblages.Surface-
complexation models (SCM)apply principles of chemical equilibrium to rcaetions
between dissolved species and potential sorption sites.A series ofheterogeneous mass-
action equations,mass-balance equations for surface sites,and charge-potential relations
ftlr each surface are coupled with aqueous-speciation equilibria to determine sorbate-
sorbcnt interactions,commonly using a geochcmical-computer code (e.g.,Parkhurst and
Appelo,1999).In geochemical model PHREEQC,surface-complexation reactions are
reproduecd ancr the Dzombak and Morel (1990)diffuse-layer model with the option to
13-4
include effects !i'om electrostatic potentials (Parkhurst and Appelo,1999).The
generalized,two-layer model quantifies the adsorption of speeiated-aqueous complexes
onto amorphous hydrous-ferric oxide (HFO)surface sites (Dzombak and Morel,1990).
Sincc the publication of Dzombak and Morcl's 1990 compilation,additional surfaee-
complexation models that focus solely on uranium(VI)adsorption have been established.
The different assumptions implicit with each surfaee-eomplexation model has the
potential to significantly affect thc quantity of uranyl (UOZ'2)and uranium(VI)adsorbed.
Potential differences betwcen the various surface-complexation models include the
absolute number and relative partitioning betwccn strong-site and weak-site densities,
coordination strueture between uranyl and HFO surfaec sites,competitive sorption
between uranyl and other dissolved species (mainly metals),and the methodology used to
compute adsorption coefficients.The relative assumptions,advantages,and
disadvantages between the various surface-complexation models are summarized in
Table B-2.
METHODOLOGY
Measurement of HFO and Neutralization Potential
The mass of hydrous-ferric oxide present in bedrock underlying the White Mesa Mill
tailings-disposal facility was determined via chemical extraction with hydroxylamine-
hydrochloride (BB)solution.Chemical extractions with BB are expected to completely
dissolve amorphous-mineral phases (e.g.,fcrrihydrite)and pmiially dissolve some
crystalline minerals (e.g.,goethite).Bedrock-core samples collected from MW-23 and
MW-30 were air dried at 34°C and crushed «3 mm).To represent the vadose zone
beneath the tailings cells,these eore samples were collected from the Dakota Sandstone
and Burro Canyon Formation at similar depths to the samples collected for hydraulic
testing performcd by Danicl B.Stephens &Associates (200?).The BB solution
(100 mL)was added to 10 grams of crushed rock in a 250 mL bottle and placed in a
shaking-watcr bath at 50°C.Aliquots of extracted solution were withdrawn after
96 hours and filtercd «0.45 rtln)prior to atlalysis.The extracted solution was analyzed
~---_._--
B-5
f()I'dissolvcd aluminum,calcium,iron,magncsium, manganese,and uranium.The HH
procedure was similar to thc methodology incorporatcd by Davis and Curtis (2003,
p.34.).The acid-ncutralization potential of the bedrock was measured directly using the
methodology outlincd in the U.S.EPA method M600/2-78-054.Sample preparation,
laboratory experiments,and water-quality analyscs were performed by ACZ
Laboratorics,Inc.,Steamboat Springs,Colorado (original data included as Attachment I
ofthis Appcndix).
Geochemical Modeling
Water-quality data for the White Mesa Mill tailings porewaters and leach-extraction data
lor the underlying bedrock was examined to calculate adsorption of dissolved species
uoder varying geochemical conditions.Neutralization of the infiltrating tailings
porewatcrs and sorption of solutes onto I-IFO was determined using the geochemical code
PHREEQC (version 2.13.2)(Parkhurst and Appelo,1999).Distribution coefficients wcrc
calculated with the following equation (Langmuir,1997,Equation 10.15):
(1)
Where:Kd is the distribution coefficient [l}M·1]
C;is the initial concentration [ML'J]
ejis the final concentration [ML·J]
V is the volume ofsolution [LJ]
M is the mass ofrock [M].
For each batch reaction,distribution coeHicients were calculated usmg the initial
concentration of the dissolved species present in the tailings porewaters at the surface
(i.e.,prior to neutralization and equilibration except for manganese,fluoride,and sulfate
as explained below),the final concentration of the dissolved species subsequent to
adsorption onto I-IFO,the mass ofrock,and the calculated volume ofsolution.The initial
concentration of a dissolved species prcsent at the surface was used during the
13-6
distribution-coefficient caleulations,rathcr than an iterative or pseudo-reactive-transpOlt
approach,in order to maintain conservative assumptions.An iterative approach would
have used the previous solution as an initial condition in the geochemical model and for
calculating adsorption f(lr each subsequent hydrostratigraphic unit.The initial
concentration of manganese,Iluoride,and sulfate were determined for each
hydrostratigraphie unit to account for mineral-precipitation reactions.
Assumptions implicit with modeling adsorption of dissolved species with the pmtition-
coeflicient approach inelude establishment of local equilibrium and completely-reversible
geochemical reactions.Furthermore,conditions simulated in the geochemical model
were assumed to be representative of expected hydrogeochemical conditions in the
vadose zone beneath the White Mesa Mill.
As part of this study,we calculated K,,'s with the Dzombak and Morel (1990)surface-
complexation model.The number of strong and weak sites and surface-complexes
considered f;)r their surface-complexation model is listed in Table B-3.Electrostatic
effects were explicitly accounted for during the calculations.Most surface-complexation
coeflicients for the Dzombak and Morel (1990)model were taken directly from the
wateq4f:thermodyanic database distributed with PHREEQC (version 2.13.2);with the
exception of a few trace metal surface-complcxation eocfficients which were taken liom
the minteq.v2-thermodynamic database Crable B-3).For the Dzombak and Morel (1990)
model,the surface-complexation coefficients for uranyl and uranyl-carbonate were
optimized against the Payne (1999)and I-lsi (1981)datasets,as explained below.
Surface-complexation reactions and coefficients are summarized in Table B-4.
Verification ofSurface-Complexation Model
The surface-complexation model described in the Payne (1999)dissertation has some
unique charaetcristics that complicate its actualization in PHREEQC.Payne set up the
models using MINTEQA2 (Allison et aI.,1991),which has a more f1exible system to
detine reactions on surfaces.PHREEQC has similar capabilities but requires the
inclusion of keywords that limit stoichiometric cheeks on the surface-complexation
-_.-----------~
B-7
equations.To verify that the assumptions and setup in PHREEQC were correct,a
comparison betwcen Payne's data (1999,Appendix 1)and the PHREEQC model-
generated output produccd as part of this study was pcrfol111ed.The Payne (1999)
expcrimental conditions included Lli of 1 x 10.6 M in a 0.1 M NaN03 solution with
0.089 g of HFO.The solutions were equilibrated in air (10.0.7 atmospheres oxygen and
10.35 atmospheres carbon dioxide)and the pH was fixed in PHREEQC by addition of
NaOH.
Figure B-3 shows thc comparison between the Payne (1999)dataset of laboratory-
measured uranium sorption values and values calculated with PHREEQC using the
surface-complexation modcls of Payne (1999)and Dzombak and Morcl (1990).The
model-predicted uranium sorption values using the Payne (1999)surface-complexation
model closcly match the laboraotory-measured values.Thc comparison demonstratcs
that assumptions and dctails of the Payne (1999)surface-complexation model can be
replicatcd using PHREEQC.Thc other model uses surface-complexation parameters
identified by Dzombak and Morel (1990).Despite differences between adsorption
predicted with the Dzombak and Morel (1990)surface-complexation model and Payne's
laboratory measurements (Figure B-3),there is a general agreement between the two
datasets.However,to improve the fit betwecn mcasurcd and modcf-prcdicted adsorption
of uranium with thc Dzombak and Morel (1990)model,the strong-site and weak-site
surfacc-complexation coellicients f()r uranyl wcre optimized to fit the Payne (1999)and
Hsi (1981)datasets.During optimization,inclusion of a uranyl-carbonate surface
complex,allowing adsorption onto wcak sites only,was ncccssary to decrease residuals
and improve thc model fit;the uranyl-carbonate surface complex was only compared to
the Paync (1999)dataset.Thc Hsi (1981)cxpcrimental conditions ineludcd L:U of
1 x 10.5 M in a 0.1 M NaN03 solution with 1 g of HFO.The solution pH was fixed in
PHREEQC by addition ofNaOH.
Figure 13-4 shows the comparison between the Payne (1999)dataset and two different
model representations:the model using the Payne (1999)surface-complexation
parameters and the model using the optimized Dzombak and Morel (1990)surface-
complexation parametcrs.The model using the optimized-parameter set is clearly
--~..•......_....•_-~_..~•.._-----_.
13-8
excellent,with a reduction of the root mean square error thllll 23.5%to 5.0%.Figure B-5
shows the comparison between the IIsi (1981)dataset and the optimized Dzombak and
Morel (1990)surface-complexation parameters,and illustrates an excellent fit between
the measured and predicted values.The two outliers at elevated pII conditions may be
attributed to laboratory erro....These comparisons demonstrate that the model setup with
the optimized-parameter set for the Dzombak and Morel (1990)surface-complexation
model is appropriate and can be considered to compute uranium adsorption onto 111'0.
Retardation Factor
Adsorption coefficients are gencrally incorporated into a solute-transp0l1 model by
multiplying the adveetive-and diffusive-transport terms by a retardation factor,which
can be calculated with the f()llowing equation (Freeze and Cherry,1979):
(
p *K )R,=I +"O·.-'!-
where Rtis the retardation factor [dimensionless]
PI>is the dry-bulk density ofthe porous media [MC3]
/(,is the distribution coefficient [L3M-']
eis the volumetric-water content ofthe porous media [L3L-3].
(2)
The retardation factor is commonly used to determine the transport of a contaminant
plume undergoing adsorption,and is measured relative to the advective transport of
groundwater (Freeze and Cherry,1979).A retardation factor of 1.0 indicates that the
contaminant plumc migrates at the same rate as the adveetive velocity,as is typically the
case for chloride.
Initial-Solute Concentrations
The average-solute concentrations mcasured between September 1980 and March 2003
f()r the tailings-wastewater (Utah Division of Radiation Control,2004)were used as an
B-9
initial condition for calculating adsorption of'solutes onto HFO (Table B-S).The initial
solution was assumed to be in equilibrium with atmospheric oxygen (21 %or 10.07
atmospheres)at the mcasured pH (1.83 s.u.).Initially the concentration of sulfate was
allowed to be adjusted to achievc charge balance;however,establishment of
electroneutrality resulted in a significant reduction in sulfiltc concentrations.Therefore,
the solution chemistry was not balanccd resulting in a final chargc-balance error of -
30%,which is regarded to bc reasonable considering the initial solution represents an
avcragc valuc.The occurrence of an imbalanced solution will not affect the calculations
because the charge-balance equation is not used to determine a solution to the
equilibrium problem.Solute concentrations originally reported in mgll were converted to
moles per kilogram of water (mol/kgw)to minimize differences bctwecn the initial and
equilibrated solutions prior to reaction with the mass of calcite and hydrous-ferric oxide
for each hydrostratigraphic unit.The pH was fixed at the mcasured value by addition of
NaOH.Equilibration of the initial solution with atmospheric oxygen was necessary to
ensure oxidized conditions that would prohibit saturation of uranium-bcaring phases and
speciation of non-uranium(VI)aqueous complexes.The wateq4f-thermodynamie
database distributed with PHREEQC (version 2.13.2)was edited to remove uranium(VI)
aqueous complexes and the input files were modified accordingly to incorporate aqueous
complexcs listcd in Table B-1;incorporation of the speciation database as part of the
model-input files cnsured complete control of the uranium-aqueous complexes used in
the calculations.fn addition,aqueous complexes and surface complexes incorporated
hom the minteq.v4.dat-filc ('rable B-3)were added to the modified database.
Uranium-Adsorption Calculations
During batch-reaction calculations performed with PHREEQC,the initial-solute
concentrations were equilibrated with:
1.quartz,gypsum,calcite,barite,rhodochrosite,pyrolusite,and fluorite,
2.the calculated mass of calcite for each vadose-zone hydrostratigraphic unit
determined hom the acid-neutralization tests,and
3.carbon dioxide concentrations measured for a typical soil (10.2.0 atmospheres)
(Sposito,1989).
B-IO
Additionally,the initial iron dissolved in the tailings porewaters was allowed to
equilibrate with amorphous-iron hydroxide (i.e.,111'0),the phases identified above,and·
the mass of calcite for each hydrostratigraphie unit;the resultant mass of 111'0 was
added to the mass determined from the leach-extraction tests.Following partial
neutralization of the tailings porewaters,the resultant solution underwent speciation and
surface complexation with the mass ofliFO (total extracted and precipitated).For each
batch reaction,distribution coefficients were calculated according to Equation 1 (see
above)using the initial dissolved uranium(VI)concentration (-94 mgll or 3.91 x 10-4
molal),the !inal dissolved uranium(VI)concentration,the mass of rock,and the
calculated volume ofsolution.
In addition to uranium,distribution coefficients of other metals in addition to sulfate,
selenium and fluoride wcre also calculated for each stratigraphic unit similar to the
approach described above.Sorption of nitrogcn spccies was not considered since the
Dzombak and Morel (1990)database does not includc this element.The results are
described bclow.
RESULTS
HFO and Acid-Ncutralization Potcntial
The mass of hydrous-ferric oxide leached ii'om the crushed-bedrock samples,and acid
neutralization-potential,is presentcd in Table 13-6.With thc cxception of two elevated
values,there was little variation in dissolved iron (and inferred mass of HFO)for the
bedrock.The absolute number of surface sites and relative partitioning between strong-
site and weak-site densities were calculated from the molcs of HFO and the site densities
listcd in Table B-3.
Gcochemical Modeling
Selected output computed with PI-IREEQC for the vadose zone hydrostratigraphie units is
summarized in Table 13-7.The average ionic strength of the initial and equilibrated
13-11
solutions for the Dzombak and Morel (1990)model was 1.32 molal,which approaches
the limits imposed by the ion-association model (i.e.,Davies Equation)used to calculate
activity coefficients.Therefore,aqueous-and surface-complexation calculations should
be considered in a semi-quantitative fi·amework.
Water-quality data ofthe infiltrating tailings porewaters indicates that sufficient buffering
minerals would be present to neutralize the low-pH waters to eircumneutral conditions.
Model simulations predicting neutralization of the low-pH fluids in the vadose zone
heneath the White Mesa Mill agree with investigations at a large number of uranium-
tailings facilities in the western United States,which have demonstrated neutralization of
low-pI-I fluids within a few hundred feet in any transport direction (INTERA,2(07).
Differences in equilibrated-solution pH resulted from the variability in the mass ofcalcite
for cach hydrostratigraphic unit.The low-pl-I solution chemistry predictcd for the third
hydrostratigraphic unit results fi'Oln the low acid-neutralization potential measured hom
the bcdrock sample and the conservative assumptions used to construct the geochcmical
model.In actuality,water moving through the third unit would represcnt the integrated
effects of water-rock reactions that occurred during transport through tbe overlying
hydrostratigraphie units (i.c.,vadose-zone watcr in this unit would likely be at
circumneutral conditions).
Spcciation of the equilibrated watcrs for the Dzombak and Morel (1990)surfaee-
complexation model is presented in Table B-8.Variability of total carbon resulted fimn
different final solution pH's and complexation with uranium(VI).
Adsorption of Uranium
At the equilibrated-solution compositions (Tables B-7 and B-8),the calculated K"values
and retardation filetors for uranium transport in the vadose zone hydrostratigraphic units
are summarized in Table B-9.Retardation filetors are only presented for the base-case
scenario for Cells 2 and 3.The calculated K"values arc considered conservative since
only iron-oxyhydroxide phases were considered as minerals that could participate in
13-12
surface-complexation reactions (e.g.,adsorption of uramum onto goethite,
montmorillonite,and quartz were not included in the model;Davis et al.2004).Inclusion
of additional BFO precipitated during equilibration of the tailings porcwaters did not
significantly affect the K"values.An additional 1.70 and 3.54 grams ofBFO was added
to the first and sceond batch reactions.
Most uranium-bearing phases wcre undersaturated except for carnotite and tyuyamunite
which were supersaturated in the first vadose zone hydrostratigraphie unit;however,
these uranium-vandadium-bearing phases were not allowed to prceipitate,which is
consistent with a more conservative approach.Iron,aluminum,and mangancse-
oxyhydroxide phases (except for the third hydrostratigraphie unit)were at conditions that
could lead to precipitation.
Adsorption ofAdditional Solutes
Sorption coefficients and retardation factors were calculated for additional contaminants
ofconcern to assess their potential transport through the bedrock vadose zone
(sec Table B-I0).The Dzombak and Morel (1990)surface-complexation model
considers competitive adsorption between a large number of dissolved species
Crable B-3).Retardation factors arc only presented for the base-easc scenario for Cells 2
and 3.
DISCUSSION AND CONCLUSIONS
The fate-and-transport potential of contaminants through the vadose zone to the
underlying perched water table beneath the White Mesa Mill is summarized in order to
draw some general conclusions regarding processcs that may control a solutes ability to
reach the perched aquifer.Two geoehcmical proccsses are hypothesized to control
solute-transport mobility 111 the vadose zone:adsorption of solutes onto BFO and
precipitation of minerals.
B-13
The results presented in Table 13-10 demonstrate a high-sorption potential for uranium
and most trace metals,especially for the middle vadose zone hydrostratigraphic unit
which contains sufficient buffering minerals capable of neutralizing the low-pH fluids
present in the tailings.The distribution eoet1icients have been subdivided into three
categories:high,intermediate,and low.Solutes predicted to have a high K"include
arsenic,beryllium,chromium,copper,lead,uranium,vanadium,and zinc.Solutes
predicted to have an intermediate K"include cadmium,cobalt,manganese,molybdenum,
and nickel.Solutes predicted to have a low K"include selenium and sulfate;while iron,
fluoride,mercury,silver and thallium were predicted to have a K"of approximately zero.
Distribution coefficients predicted with the geochemical model generally agree with
published estimates,with the exception of cadmium,cobalt,iron,manganese,mercury,
nickel,selenium,silver,and thallium.Based on values reported by Sheppard and
Thibault (1990),U.S.EPA (1996),and U.S.EPA (1999),distribution coefficients for
these solutes arc likely to be significantly larger than model predictions presented in
Table 13-10.
As described in Section 4.0 of the Infiltration and Contaminant Transport Modeling
Repol1,uranium,as a result of the solute's strong capacitance for sorption and resultant
high-retardation coefficients,is predicted to migrate a limited distance below the liner
system in 200 years;uranium is not predicted to reach the perched aquifer within
200 years.Similarly to uranium,the metal species with high to intermediate distribution
coefficients discussed above are also expected to be transported a limited distance
beneath the liner system in 200 years.Sorption ofselenium,iron,mercury,and thallium
are expected to be larger than the model predictions,and these solutes are not expected to
impact water quality in the perched aquifer within 200 years.
Mineral-saturation indices presented in Table 13-11 demonstrate that dissolved
concentrations of sulfilte and manganese,and to a lesser extent fluoride,in vadose-zone
porewater will be predominately controlled by mineral-precipitation reactions.The
initial concentration of sumlte in the tailings porewater was reduced from 64,330 to
44,248 mg/I,primarily from the precipitation ofgypsum and to a lesser extent barite.The
concentration ofi1uoride was reduced from 1,679 to 1,175 mg/I through the precipitation
13-14
of Huorite;and manganese was reduced limn 145 to 0 mgll through the precipitation of
pyrolusite.Additionally,concentrations of iron and aluminum in vadose-zone porewater
arc expected to bc controllcd by prccipitation of iron and aluminum oxyhydroxidcs,and
are not expected to impact water quality in the perehcd aquifer within 200 years.
Equilibrium calculations also indieatc that two uranium-vanadium-bearing phases
(carnotite and tyuyamunite)arc cxpectcd to prccipitate in the vadose zone,which would
act as a sink for thesc two solutes.
Given the high-pe conditions of the tailings porcwater following equilibration with
atmospheric oxygen,most of the total nitrogen was present as N(5+)and speciated as
nitrate (NOJ)The average concentration of dissolvcd nitratc for thc initial conditions
and thrce hydrostratigraphic units was 10,127 mgll;concentrations of nitrite and
ammonia were approximately zero.Adsorption of nitrogen species was not determined
since the Dzombak and Morel (1990)surface-complexation model does not contain any
nitrogen species.As a result,nitrate is expectcd to be conservatively transported through
the vadose zone,similar to chloride.Considering the low water Huxes through the
vadose zone and reduced difllision coefficient of nitrate as compared to chloride,nitrate
is not expected to impact water quality in the perched aquifer within 200 years.
In summary,adsorption of contaminants onto HFO and precipitation of minerals in the
vadose zone should limit the mobility of most trace metals in addition to uranium and
sulfate.Furthermore,thc calculated Kd values and retardation factors arc considercd
conservative because:
1.only a single iron-oxyhydroxide phase was considercd to participate in
surface-complexation reactions (e.g.,adsorption of metals onto aluminum-
oxyhydroxidcs,gocthite,montmorillonite,illite,and quartz wcre not included
in thc model);
2.coprecipitation of uranium (Abdelouas et aI.,1998)and metals onto the
surf[lces of precipitating phases (e.g.,hydrous-ferric oxide,sulfiltes,
carbonates)was ignored,which could also serve as a sink for metals;and
3.neutralization of infiltrating tailings porewaters was calculated fllr each
individual bedrock unit and not with an iterative (pseudo-reactive transport)
13-15
approach,which would serve to increase sorption !()r the third
hydrostratigraphic unit.
REFERENCES
Abdelouas,A.,W.Lutze,and E.Nuttall,1998.Chemical reactions of uranium in ground
water at a mill tailings site,Journal ofContaminant Hydrology,34,343-361.
Allison,J.D.,D.S.Brown,and K.J.Novo-Gradac,1991.MINTEQA2IPRODEFA2,a
geochemical assessment model for environmental systems,Version 3.0 User's Manual:
U.S.Environmental Protection Agency Report EPN600!3-9I/02l,106 p.
Bernhard,G.,G.Geipel,T.Reich,V.BrendleI',S.Amayri,and H.Nitsche,1992.
Uranyl(Vl)carbonate complex formation:Validation of the Ca2U02(C03)3 (aq)
species,Radiochim.Acta,89,8,511-518.
Daniel B.Stephens &Associates,2007.Laboratory Report Prepared !()r MWH
Americas,Inc.,April 27,2007.
Davis,J.A.and G.P.Curtis,2003.Application of Surface Complexation Modeling to
Describe Uranium(VI)Adsorption and Retardation at the Uranium Mill Tailings Site
at Naturita,Colorado,RepOlt NUREG CR-6820,U.S.Nuelcar Regulatory
Commission,Rockville,MD.,pp.223.Available at
hl1p;(6."y.;}YcDl'U\ov!readingJ:m!f!oc-collectiems!nuregs!coIJJn!c;t!er6820!er682J!JJdf.
Davis,.l.A.,D.E.Meece,M.Kohler,and G.P.Curtis,2004.Approaches to surface
complexation modeling of Uranium(VI)adsorption on aquifer sediments,Geochimica
et Cosmochimica Acta,68,18,3621-3641.
Dzombak D.A.and F.M.Morel,1990.Surface complexation modeling:hydrous ferric
oxide,John Wiley &Sons,New York,NY,pp.416.
Freeze,R.A.and J.A.Cherry,1979.Groundwater,Prentice-Hall,Inc.,Englewood Cliffs,
N.J,pp.604.
Grcnthe,I.ct aI.,1992.Chemical 717ermodynamics of Uranium,Elsevier,Amsterdam,
The Netherlands,pp.716.
Guillaumont,R.ct aI.,2003.Update on the chemical thermoc!ynamics of Uranium,
Neptunium,Plu/onium,Americium and Technetirtm)Elsevier,Amsterdam,The
Netherlands,pp.919.
Hsi,Ching-Duo Daniel,1981.Sorption of uranium (VI)by Iron oxides,Ph.D.
Dissertation,Colorado School ofMines,pp.154.
B-16
INTERA,2007.Revised Background Groundwater Quality Report:Existing Wells for
Denison Mines (USA)Corp.'s White Mesa Uranium Mill Site,San Juan County,
Utah.Prepared for Denison Mines (USA)Corp.October 2007.
Langmuir,D.,1997.Aqueous Environmcutal Geochemist/y,Prentice-Hall,Inc.,
Englewood Cliffs,N.J.,pp.600.
Moll,H.,1997.Zur Weehselwirkung von Uran mit Silicat in wiissrigen Systemcn,Ph.D.
Dissertation,Teehnische Universitiit Dresden.
Parkhurst,D.L and CAJ.Appell),1999.User's guide to PHREEQC User's Guide to
PHREEQC (Version 2)--A Computer Program for Speciation,Batch-Reaction,One-
Dimensional Transport,and Inverse Geochemical Calculations,U.S.Geological
Survey Water-Resources Investigations Report 99-4259,pp.312.
Payne,T.E.,1999.Uranium(VI)interactions with mineral surfaces:controlling factors
and surface complexation modeling,Ph.D.Dissertation,University of New South
Wales,pp.332.
Sandino,A.and J.Bruno,1992.The Solubility of (U02)3(P04)2'4H20(s)and the
Formation ofU(Vl)Phosphate Complexes:Their Influence in Uranium Speciation in
Natural Waters,Geochimica et Cosmochimica Acta,56,4 135-4145.
Sheppard,M.I.and D.H.Thibault,1990.Default soil solid/liquid partition coefficients,
K"s,for f(lUr major soil types:a compendium,Health Physics,59(4),47 I-482.
Silva,R.J.,1992.Mechanisms for the Retardation of Uranium(VI)Migration,Mat.Res.
Soc.Symp.Proc.,257,323-330.
Silva,R.J.et aI.,1995.liwrmodynamics 2;Chemical 711ermodynamics ofAmericium,
with an appendix on Chemical Thermodynamics of Uranium,Nuclcar Energy
Agency,OECD,North-Holland,Elsevier.
Sposito,G.,1989.The chemistry ofsoi/s,Oxford University Press,Inc.,New York,NY,
pp.277
U.S.EPA,1996.Soil Screening Guidance:Technical Background Document,
Publication 9355.4-17A,2nd ed.,Office of Solid Waste and Emergency Response,
U.S.Environmental Protection Agency,puhlished May 1996.
U.S.EPA,1999.Understanding variation in pmiition coefficient,KI,values:Review of
Geochemistry and Available K"Values for Cadmium,Cesium,Chromium,Lead,
Plutonium,Radon,Strontium,Thorium,Tritium (3H),and Uranium,Volume II,
Publication 402-R-99-004B,Ot1iee of Air and Radiation,U.S.Environmental
Protection Agency,published August 1999.
-------~..._~..._--_.__._-----~-..._------_._--
B-17
Utah Division of Radiation Control,2004.Draft Ground Water Discharge Permit,
Statement of Basis for a Uranium Milling Facility at White Mesa, South ofBlanding,
December 2004.
Waite,T.D.,J.A.Davis,TE.Payne,G.A.Waychunas,and N.Xu,1994.Uranium(VI)
adsorption to ferrihydrite:application of a surfacc complexation model,Geochimica
et Cosmochimica Ac/a,58,24,5465-5478.
Wazne,M.,G.P.Korfiatis,and X.Mcng,2003.Carbonate effects on hexavalent uranium
adsorption by iron oxyhydroxide,Environmental Science &Technology,37,3619-
3624.
--~..-_._'~_..-_._-"_....
13-18
Eh -pH Diagram for the System U - 0 - H at 25'C
1.5,-----------------,
LU=10·e M
pco2 =0
after Langmuir,1997
o
·0.5
UO,(OH),-
UO;(c)
-1
o 2 4 6
pH
8 10 12 14
Figure B-t.Eh pH diagram for the system U -0,-J-1,O in pure water for ~U =JxlO-8
M.The UO,(e)solid/solution boundary is represented by the green line,(after Langmuir,
1997).
Distribution of Uranyl Species
IV =10"M,IC(IV)=0.001M
10987
--U02(C03)3-4
..-.U02C03
- -.(U02)2C03(OH)3:
5 6
pH (su)
.-.U02(C03)2-2
-U020H+
-(U02)3(OH)5+
43
-U02+2
-U02(OH)3·
- - -(U02)2(OH)2+2
U02+~//1-/
7/
(UO,),CO,(OHj,:"-.:.;/',I.,.
(i(O,),(OH!,.,·/'--....,
1.0E-09\:'//\I
UO,CO;, ,"I
,(UO,h(OH),i1.0E-10 .L-__~~L-.c:"",,~_..£--'.~__.->__---'
2
1.0E-07
1.0E-06 .
~E]1 1.0E-08
o:;;
Figure B-2.Distribution of Uranyl Complexes as Fnnction ofpH for LU =I.OxlO-6 M
and LC(IV)=0.00I M calculated with the project-specific thermodynamic database.
Comparison of U(Vl)sorption on ferrihydrite as a function pH
80
~60
fro"-,::J 40
20
4 5 6
iT--
I
7
pH (S.U.)
I
It
I
I
8
III I
.!
t
9
I
II
I
iIti---
I:
10 11
•measured Payne 1999 0 predicted Dzombak and Morel 1990 0 predicted Payne 1999
Figure B-3.Comparison ofPayne (1999)laboratory-generated data (filled diamonds)
and model-generated fits for uranium (uranyl adsorption)calculated with PHREEQC
using the (i)Payne (1999)surface-complexation model (open squares)and (ii)Dzombak
and Morel (1990)surface-complexation model (open circles).
Comparison of U(Vl)sorption on ferrihydrite as a function of pH
20
4 5 6 7
pH (s.u.)
8 9 10 11
1999 0 D7.0mbak and Morel 1990 o
Figure B-4.Comparison ofPayne (1999)laboratory-generated data (filled diamonds)
and model-generated fits for uranium (uranyl adsorption)caleulated with PHREEQC
using thc (i)Payne (1999)surface-complexation model (opeu squares)and (ii)Dzombak
and Morel (1990)surface-complexation model after optimizing the uranyl and uranyl-
carbonate surface-complexation coefficients (open circles with solid connecting line).
Comparison of U(VI)sorption on ferrihydrite as a function of pH
10000 .r---~-------------~---_.--_.'--------'
~"..1000····4 ........
oJ 100 .~
._-----_..._",,--_._--_.
10 .-""~"."'••".--._--...iI!.
_A_.._
1197 8
pH
~-t-·__·---+----c_---r____---'--
10654
0.1
3
...measured fHf~sii-1119)181'11..-...•--60•.:..pr';di(~t~(i[)Dzz(o)rmnlb~alkk ,a,~ndd rvMoreI1990)(~l'iiIIl1I;Od)
Figure B-5.Comparison ofBsi (1981)laboratory-generated data (fillcd triangles)and
model-gcncrated fits for uranium (uranyl adsorption)calculated with P1-IREEQC using
the Dzomhak and Morel (1990)surface-complexation model after optimizing the uranyl
and uranyl-carbonate surface-complexation coefficients (open circles with solid
connecting line).
Table 8-1_CompariSO'l01 aqueous-complex formali"n (slab,:ity)coelf,cienl5 be~...."e"Ihe,medyMmicoalabases.AlldalaWe'"calculatedal351""0",dlem;><>'3tufe 0125 -C and a pressureofG.~MPa al i,,:'n;le d,:ulion (zoroio~io sl'''r:glh).
This StUdy Davis and Curt;s (2C03)I PaYM (1999)I G"Hlaumor.!el a!(20D:l)W.:NTEQ,V4 (2C07)I WA,E04F(20D7)
,..umbOf corr.olex 'eacl;or.100 K(-,efe'ence I K -,,,fe'e.~ce,10";<-)'cfare""",,,-relereneo Icc K ._j 'efo'ence 100 K __),,,ICfence
V01-OH-cor:-.plexes equalion ,
UO,(CHj'H,O+UO,""H'+U010f;"_5.25 ·I -52 ,
I
_5.2 -5250 ·_5697 -52
V01(OH),."2H,O·UO,""ZH'+UO,(OHh..,_12 ~5 a,b ';_"<1.5 "-12 ·"<2.15 •
UO,(OH);3l-i,o+VO,'-"3H-..UO,l,OH);_20,25 .,.","'I -2025 •-<,9.2
UO,(OH)/-4l-i,o+UO,'-"4H'•L:O,(OH),'"_324 ..,·33 ,."_324 •.",(UO,),(OH)"H,O·2UO,"'"H'·(U01loOH'--27 ..,-27 ,I ·2,8 -2,7 ,-2.7,(UO,),(OH),"2H,0+2UO,""2H'..(UO/),(OH)}'_5,62 ..,-562 ,I -5.63 -562 •·5.574 -562,{UO,hCOH),"4H,0.3UO,""4H'+(UO,),(OH).".11.9 "I -11.9 ,I -1 ~.9 _1j.9 •-11.9,(UO,),(OH);5H10+3UO/'=5H'+(VO,),(OHl;-555 "-1555 o i ·<556 -1555 ··"<5565 ·1555
9 7H,0+3UO,"~7H'•(UO,J:,(OH),-32.2 -31 !-32.2 ,-31(UO,l,(OH),•~.I -31 •I10(UO,i,(Ol-q;7H,o+4UO,""7H'+(UO,),{OHl,'_21.9 "_21.9 _21.9 •i -21.9IiI,,
n"m;,er U01_CO,_Q<lm;:lpxcs equa:ion '109 K(••)'efe,ence log K(-)reIQ'e~ce !log K(_.j 'Q:e'enCQ i leg '<(-)'eference Ilog K(-)'eferenee log K(-)'e:e'ence
UO,CO,.....CO,""UO,"~UO,CO,..,I 9,94 •9.67 ,9.'I 9,94 •"963
UO,CO,,,,HCO;+uo/-"UO,CO"..,·lH'I
UO,(CO,l,"2CO,"+UO,""UO,(CO,)/"I 16.61 ·',6,94 ,"I 16,6"<,16.9 "l;O,(CO,j/'2l-iCO;~vot "VO,lCO,jt..21-1'I
IUO,(CO,),"3CO/'"UO/'=VO,(Co,),"2"«\4 •21.6 ,21.63 21.34 ·21,6 21.63
VO,(CO,h'-3HCO;+uot"UO,(CO,),'·..3H'IUO,lCO,),;'3CO,'"..vO,""UO,(CO,),!i-6,95 •,6.9S •743
U01(COI),>-3HCO;"uo,'-"UO,(COlh>-+3H'I{uo,),(CO,),"6CO}-+3UO{'"(UO,h(CO,l,""..,"0 "·"
numbe'uO,-COl-OH-complexes equalion 10gK(-),efe'ence legK(-j refetence log K(_)re~e'ence 10gKH ,e:elence log K(_)re;"'en~e log K(-)reference
(UO,hCO,(OHh-CO,'..2UO,""3H/O"(UO,hCO,(OH);..3H'-0,86 ,.0.86 ,-1.18 reactionwiCO'-,
(UO~),CO,(OH),'CO:'..3UO,"..3HP"(UO,),CO~(OHh'+3H'C.66 ,0.66 ,'eactionwiCO,.,
(UO,h,(CO,l,{OH),,"6CO,'·.11UO/'..12HP"(UO,l,,(CO,MOHl,~"""<2H'36.43 ,36.43 ,'eac:ienwiCO/.,
number UO,.Ca-CO,-eem~lcxc5 equation 10gKH refe'ence logK(-)refefe"Cl>log K(-),e~erencc ic;K(-}rele,ence 110;K(••)re;e,~nceI109 K(_)feference
CaUO,(CO,j,-"3CO,·..Ca'·.Uo,'"~CaUO,(CO,),-25.4 ·25,4 .
Ca,UO,(CO,h""3CO/'..2Ca"..UO,""CaUO,(CO,h..,30SS ,30.$5 .,,I
n,,"'';:e'UO,.F.CO,_complexes equat;on logKH referenoe 10gK ( )refefe.oce I log K(-)reference I leg K(-)'eference log K(-i rele,encellcg K( )rero'ence
UO,CO,F'CO,"+F'+UO,'-~UO/CO,F"1375 •i 13.75 ·IUO,CO,F,"CO/'+2F'"UO,1-~UO,CO,F,"15,57 ,15.57 •IUO,CO,F,'"CO/'.3F'+UO,""U01CO,F,"16,38 •16.33 •
n~",bar UO,·Ha'oge"_complexes e~~al'O~1ogK(--)re:e'ence !ogKH relerenc"logK(-)'efefenc~legK(--}re~erence log K(_.j r~f",enceII09 K(-)'e!e'e~ce
UO)·F'..UO",~UO,F..516 ·5.16 •5.14 '.W
UO,F,."2F-"UO,'-=UO/F,...,8,33 •I 8.63 ·'.6 8,62
UO,F;31'--+UO,"=UO,F;~0.9 ,109 •"109
UO,";-4F'"VO,"=UO,F/11.84 ·I
11,64 •11.9 '"U01CI'CI'"UO,'·~UO,CI'0.-.7 a,c 0.17 ,0.17 ,0.2"<C.17
UO,CI/..,2et+uO,""UO/ei/_"_1,1 ..,.1.1 ,-1.1 •.1.1
num~er
~vmbe,
numb~r
nur:>te,
num~e'
~vmbe'
This Study IDavisandCurtis (2003)I Payn\)(1999)Gv;::avmon!e!al.(2e03),I~~Ii'iTEO.v4 (2007)I WATE04F (20J7)
UO,..SO,_comol~xos ~qua!ion ~o;K(--)reo,ence·iogK(_),efe'ence 10SK(-}'efcrence log K(-)reference log K(_)raferencnl iog K(-)rdercnco
V01SO..,SO,'·..VO,'--VO,sO,.",3,15 M !'"
,
I
3.15 3.15 ,I 3.18 I :>.15
VO,($O,),1-2S0/·...UO"·,,VO,(SO,,/"4,14 "4.14 ,4.14 4.14 ,"4,14
UO,(SO,),'·3S0.'-...VO,'·"UO,ISO,):3,02 ,,
3.02I
UO,-PO,-com~:cxes eqva:io~.10gKH re'erence logK(_)refe'enoe I logK 1_)re!erence 10gKH r,-,:e,en~e Ilog K(--J refe'ence :0£1 K (--',efe'Mce
VO,pO;PO...·~VO,'·-VO,PO;
I
13.23 '"1".23 ,13,23 13.23 ,13,25 13,$9
VO,PO,HPO,"~00,'-=UO,PO,...H"
VO,HPO,.,PO,"..'Jot~H·=VO,HPO,_"19.59 ,19,59 ,1959 \9,655 20,2~
UO,HPO,.,HPol·...L:O,"=UO,HPO,~,7.24 ,
VO,(HPO,){2PO."~va,'·...2H·~VO,(HPO,),"42,988 43.441
VO,H,OO,·po:-+VO,,·...2H·=OO,H,PO:2282 ,22,82 ,22 82 22833 22,87
VO,H,PO,·H'pO".~VO,'"~H·...:.lO,H,PO;112
VO,H,PO,-HPO/"~vo,'·~H""VO,H,PO;
VO,(H,PO,);3PO.'·~Vo,'·~6H-"VO,(H,PO,);I66245 I66245
VO,H,PO,'-PO,"..Vo,'·~3H'"VO,H,PO,'·22 45 ,22.45 ,22.46 22,813
VO,H,PO,'·H,PO,,",'"vo,'·"VO,H,PO,'-!0.76
VO,HPO,'-HPO,'-~VO,'·2H-~VO,H,PO;·
UO,(H,PO,),,,,,2;>0)'"vo,'"~4H'"UO,(H,PO,h,,,,,44.04 ,44.04 ,44.04 I 44.7 I 44.35
VO,(H,PO,)"""2H,PO"",~vo,'·"2H·...VO,(H,PO,),.",0.64
UO,(H,PO,l"",2HPO/'"vot...2H'"~UO,(H,PO,)"""
UO,(H,PO,)(H,PO.)"21"0.'"...vo/·...SH·"UO,(H,PO,j(H,po,f 45.05 ,45.05 ,45,05
UO,(H,PO,)(H,PO,)·2H,PO,,.,'"00/'"H·"VO,(H,PO,)(H,PO,)'1.55
UO,(H,PO,)(H,PO.j"2HPO,'-~uo,,·...3H""UO,(H,PO,)(H,PO,j"
iPO,-complex eqvatio~logKH reference logK(-)referenoe !ogKH rere'e~ce '09 K(-)'eference Ilog K(__)re:erence!lcg K(_)'eferenca
H,PO,PO,~"'3H-~H,PO,21.702 ,21.702 d I I
VO,_NO,_CQm~:e"es e<:ualion !ogK(--)re:Q,oncc ~ogKH reference leg K(-)refelence I log K(-)rofe'ence Ilog K(-)refe,e~cellogK(-)re,crence
VO,NO;NO;'"VO,- -VO,NO,·0.''.d 0.3 ,03 ,e~er:ncJ 0.''J"'I"UO,..S:O,·complexes equahon 10gKH re!cre"o"logK(_)refe'ence logKH 10gK(-)re:orcncc log K(-J 'efe'ence log K(-)'eference
VO,SiO(OHh·VO,,...SiO,(OH),'·...H'=UO,SiO(OH);21,54 "IV02'·~H,SiO,"VO,siO(OH,,"+H·_1.46 I
referenceIUO,H,SiO;VO,'·...H,SiO,=UO,H,$iO:~H·I 1_1.9111I
UO,.AsO,_com~1e"eS eeuali"n IcgKH refere~ce 109K(-)reference i log K(_)10gK(-)refere~ce log K(__)'eferencel10g K(_)re~ere~oe
UO,HAsO,.,VO"'"AsO/·~H-=UO,HAsO"..,18,75 ,
I I
18.76
VO,H,AsO;vot...AsO,"~2H·eo VO,H,AsO,'21,96 ,21.96
UO,(H,AsO,h,,.,VO;'-...ZAsO/""4H"=VO,(H,AsO.n.",41.53 ,4~.53
a"reportcd Gvi!laumor.t el al.(2C:03)
b"reported Davisand Cunis (2003).rep,cdvceda!le,Silva (1992)
C='epo'!e<l Davis andCvrti$(2003).'cproduced afterSandino a~d 8r..JnO (1992)
d"'epMed Davisa~d Cu'lis (2003).'eproduced3fterG'cO!hcel31.(1992)
c"r€pOMd nDavis and Curtis(2003)aO«!Oav,s1>\ai,(2004).rep,ocuced after8emha'de',",(20-01)
'oO rewri:le~wiH,S;O,.similarto G,e,,:h~et ai,(1992)
9"reporoed in Davis a-od Curtis(2003),reproducedaf!~'Silv~0:al.(1995)
h"reportad:n Oavis and Curtis(2e03).rep,educeda~w Moil (1997)
i~rc;>orted in Payne (1999)
i"MINTEO,V4 Febwary2007 rcieas~with PHREECC (version 2.\3.2l
k"WATE04F Febrvery 2007 releasewith PHREEOC(version 2.13.2)
Table B-2.Comparison between different surface-complexation models (SCM)ofuranium(VI)adsorption onto ferrihydrite or
hydrous ferric oxide (BFa).
SCM COMPARISON CRlTERIA
Dzombak and Morel 1990 Assumptions I Advantaoes Disadvantaaes !:
[I
Diffuse-layer model with Adsorption of inner-sphere Surface-complexation reactions Ion-adsorption coefficients Ielectricaldouble-layer complexes including uranyl onto are easily simulated with detennincd independently based
corrections considering a ferrihydrite via uptake on geochemical codes (e.g.,on simple electrolyte solutions;
two-site binding model.monodentate surface sites.PBREEQC and MINTEQA2)for a effects due to competitive sorption
variety ofcommon dissolved from other charged species
Total site density of0.205 mol species including most metals.ignored.
sites/mol Fe and 0.005 moles of
strong sites determined from Dzombak and Morel's (1990)i
mean value ofdataset.BFa database does contain adsorption,surface area 600 m-/g.coefficients for most major
cations/anions,which allows ,
There are 40-fold more weak competitive sorption to be I,
.sites than strong sites.modeled.I
Adsorption coefficients
determined empiricallv.
Waite et al.1994 Assumptions I Advantaoes Disadvantal!es II!II
Diffuse-layer model with Uranyl adsorption as an inner-Model able to explain Sensitivity ofFe concentration (as
elect!cal double-layer sphere complex onto ferrihydrite experimental dataset for a wide BFa)not evaluated.
corrections considering a via uptake on bidentate surface range ofdissolved uranium(VI)
two-site binding model.sites.and pB conditions and a limited Surface properties of BFa are
range of ionic strength and pCO,.assumed equal to values reported
Total site density set to 0.875 by Dzombak and Morel (1990).
mol sites/mol Fe and the number Considers competitive sorption of
Iofstronosites(equal to 0.00184 carbonate onto ferrihvdrite in Ion-adsorption coefficients
mol/mol Fe)was determined via presence ofuranyl and varying I determined independently based
optimization to the measured pH.,on simple electrolyte solutions;
(laboratory)adsorption data.I effects due to competitive sorption
HFO surface area 600 m'/g,Model results suggest that only .from other charged species
one postulated ternary uranyl-ignored (excluding carbonate).
There are 485-fold more weak carbonate surface complex may be
sites than strong sites.necessary to simulate uranium(VI)
adsorption.
As compared to Dzombak and ,
Morel (1990),the number of
weak sites increased 4.4-fold and
strong sites decreased 2.7-fold.
Adsorption constants determined
through optimization with
FITEQL.i
,Payne 1999 Assumptions i Advantages Disadvantages 'I
Diffuse-layer model with I Same as Waite et al.1994.Considers competitive sorption of Surface properties of HFO are
electrical double-layer carbonate,sulfate,and phosphate assumed equal to values reported
corrections considering a onto ferrihydrite in presence of by Dzombak and Morel (1990),
two-site binding model.uranyl and varying pH.
Ion-adsorption coefficients
Surface-complexation reactions determined independently based
were simulated with MINTEQA2 on simple electrolyte solutions;
after altering mass-balance effects due to competitive sorption
equations to accommodate from other charged species
bidentate nature ofuranyl sorption ignored (excluding carbonate,
onto ferrihydrite.phosphate,and sulfate).
Model able to explain Results sugaest the postulated
,I experimental dataset for a wide occurrence of a ternary surfaceI
I range ofdissolved uranium(VI)complex between uranyl and
and pH conditions and a limited phosphate.Lacking spectroscopic
range ofionic strength,pCO"and verification,predicting IamountofHFO.uranium(VI)adsorption with this
species should be exercised with
I caution.
i Wazne et al.2003 Assumptions i Advantao-es Disadvantao-es
Diffuse-layer model with Monodentate adsorption of SCM simulating monodentate Number of strong and weak sites
electrical double-layer uranyl,uranyl-monocarbonate,surfaces-site coordination of not mentioned.
considering a one-site and uranyl-dicarbonate as inner-uranyl and uranyl-carbonate !
binding model was used.sphere complexes onto species was able to predict Surface properties ofHFO are
ferrihydrite surface sites.adsorption under a wide range of assumed equal to values reported
pH and carbonate concentrations by Dzombak and Morel (1990).
Total site density set to 0.875 for experimental and
mol sites/mol Fe.The number of contaminated-groundwater SCM ignores competitive
strong sites was not mentioned.solutions.adsorption effects from phosphate
I HFO surface area 600 m'/g.and sulfate;unfortunately
Surface-complexation reactions concentrations ofcontaminated
Adsorption constants determined were simulated with MINTEQA2 groundwater are not presented to
through optimization by without altering mass-balance verify this assumption.
minimizing the root-mean-equations due to monodentate
square error (RMSE).surface-site assumption.SCM developed by Wazne et al.
(2003)does not evaluate
Ion-adsorption coefficients sensitivity ofHFO concentration.
determined for uranyl and uranyl-
"",rhArl"t""<."1"'\"'''''';''''''c.j1'Y'llllt<:l-n",r.llC'l~,
!Ib;;;;;;;;~~l;-;I;;;;;;;;;;:-,i I
I I solutions.I,I
Davis et al.2004 Assumptions Advantaaes Disadvantao-es
For component additivity Same as Waite et a1.(1994)but Demonstrated that SCM developed More complicated,site-specific
approach,model set-up with increased level of by Waite et a1.(1994)can be used model not easily implemented
similar to Waite et a1.(1994).complexity due to modeling to predict uranium(VI)adsorption without experimental
adsorption with additional for natural sediments and synthetic determination ofHFO and surface
However,natural sediments sorbing phases.I contaminated-groundwater area.
and synthetic groundwater I solutions under certain
solutions were used to Assumes all iron dissolved from I environmental conditions.Results indicate that other sorbing
conduct batch experiments.grain coatings was present as I phases should be considered as
ferrihydrite.!Experimentally determined surface part ofthe surface-complexation
Also examined adsorption I area was used in model modeling exercise which
due to surface-complexation ,simulations.necessitates a more complex
reactions with quartz,I conceptual model for natural
montmorillonite,and goethite systems.
for different laboratory
conditions.I As presented in Davis et a1.(2004,
I
I
Fig.9),the Waite et al.(1994)
SCM significantly underpredicted I
uranium(VI)sorption at elevated
pCO,'s.
Table B-3.Absolute number and relative partitioning between strong-and weak-site densities in addition to aqueous species considered
for the two surface-complexation models.
Surface-complexation model
Dzombak and Morel (1990)
Payne (1999)
total surface-site density strong sites
0.205 mol sites/mol Fe 0.005 mol sites/mol Fe
0.875 mol sites/mol Fe 0.00184 mol sites/mol Fe
weak sites
0.200 mol sites/mol Fe
0.8732 mol sites/mol Fe
HFO surface areai:f
600 m'/g
600 m"/g
Surface-complexation model
Dzombak and Morel (1990)o:ed
Payne (1999)
Surface complexes considered for adsorption onto HFO
Protonation,Deprotonation,Calcium,Strontium,Barium,Silver,Nickel,Cadmium,Zinc,Copper,
Lead,Magnesium,Manganese,Uranyl,Uranyl-carbonate,Iron,Berjllium,Cobalt,Chromium,
Chromate,Mercury,Thallium,Phosphate,Arsenate,Arsenite,Borate,Sulfate,Molybdate,
Vanadate,Selenate,Selenite,and Fluoride
Protonation,Deprotonation,Uranyl,Uranyl-carbonate,Carbonate,Phosphate,and Sulfate
'Value taken from Dzombak and Morel (1990).
b Sorption coefficients taken from Dzombak and Morel (1990)as distributed with PHREEOC Version 2.13.2 (wateq4f.dat)except those noted below.
C Strong-site and weak-site sorption coefficients for uranyl and the weak-site sorption coefficient for uranyl-carbonate were optimized to fit
the Payne (1999)and Hsi (1981)datasets.
d Sorption coefficients for Beryllium,Cobalt,Chromium,Chromate,Mercury,Molybdate,Thallium,and Vanadate taken from Dzombak and Morel (1990)
as distributed with PHREEOC Version 2.13.2 (minteq.v2.dat).
Table 8·4.Comparison between surface-complexation reactions and coefficients for the P<lyne (1999)and Dzomb8k and Morel (1990)
surface-complexation models.
Payne 1999 IDzombak and More!1990
K(:J f ~I KI)feqBrOn'1 [0 dadsorbatembenufSle ) n -u,,_9iL re erence 09 --re erence
1 proton<ltion strong SOH +H'SOH,'6.62 a 7.29 d
2 protonation weak WOH +H'"'WaH,'6.62 a 7.29 d
3 deprotonalion strong SOH:::SO'+H'-9.24 a -8.93 d
4 dcprolonation weak WOH:::WO-+H'-9.24 a -8.93 d
number adsorbate site bond equation Ion K (--\reference Ion K 1--)reference
5 UO,"strong S(OHh +UO/'-SO,UO,+2H'·2_35 a
6 UO},weak W(OHh +UO:/':::WO,UO,+2H'-6.06 a
7 UO/'strong SOH +UO,"'"SaUD,'+H'4.15 e
8 UO,"weak WOH +UO/+=WOUO,'+H+2.05 f
9 UO/'-C03'-strong S(OHh +UO/'+CO/-'"SO,UO,CO/'+2H'4.33 a
10 U02"-C03"weak W(OHh +UO}'+cot =WO,UO,cot +2H'0.24 a
11 UO,"-C03'-weak WOH +UO/'+cot:::WOU02C03-..H'9.85 9
number adsorbate site bond equation Ion K 1__1 reference Ion K1--'reference
cot ---SOH +H++C03"soeo?,H,O12strong 11.48 a
13 eo/"weak WOH +H'+C03
2-:::WOCO,-+Hp 11.48 a
14 CO/-strong SOH +2H'+CO/-'"SOe02H +Hp 19.58 a
15 eo3'-weak WOH ..2H++cot:.::WOC02H +H,O 19.58 a
16 P04
3.strong SOH +PO/"+H'=SPO/+H2O 18.05 b
17 P043.weak WOH +PO/-+H''"WPO/+Hp 18.05 b 17.72 d
18 sol strong 80H ..sol '"80H80/0.24 c
19 80/weak WaH +80/-=WOHSO/-0.24 c 0.79 d---_..__.-----
Note 1:Additional surface-complexation reactions and coelftcients included as part of the Dzornbak and Morel (1990)mode!are included
with PHREEQC (version 2.13.2).
Note 2:Two separate uranyl surface-complexation reactions and coefficients are necessary to account for the Payne (1999)and
D20mbak and Morel (1990)assumption of bidentate and rnonodentate adsorption of uranyl,respectively.
a'"from Payne (1999),Tables 11.1 and 11.2.
b '"from Payne (1999),text and equations 13.5 and 13.6.
c '"from Payne (1999),text and equation 11,11.
d:::from Dzombak and Morel (1990),reproduced as part of PHREEQC (version 2.13.2).
e =original value (5.2)from Dzornbak and Morel (1990),optimized against Payne (1999)and Hsi {1981}datasets.
f:::original value (2.8)from Dzombak and Morel (1990),optimized against Payne (1999)and Hsi (1981)datasets.
g:::parameter included to improve the fit at elevated pH conditions,optimized against Payne (1999)dataset.
Tabte B-5.Initial-solute concentrations for the tailings wastewater measured at the White Mesa Mill
prior to equilibration with Qxygenfl•
Analyte Value Units
Aluminum 1827 mg/l
Ammonia 3131 mg/l
Arsenic 149 mg/l
Barium 0.048 mg/l
Beryllium 0.5 mg/l
Boron 6.9 mg/l
Cadmium 3.4 mg/l
Calcium 368 mg/l
Chloride 4608 mgl!
Chromium 6.2 mg/l
Cobalt 60.7 mgl!
Copper 234.4 mg/t
Fluoride 1695 mg/l
Iron 2212 mg/l
Lead 3 mg/l
Magnesium 4774 mgl!
Manganese 146 mgl!
Mercury 3.5 mg/l
Molbdenum 52.8 mg/t
Nickel 82.6 mg/t
Nitrate 24 mg/t
Phosphorus 273 mg/t
Potassium 433 mg/t
Selenium 1.4 mg/t
Silicon 210 mg/t
Silver 0.1 mg/t
Sodium 5809 mg/t
Strontium 7 mg/t
Sulfate 64914 mg/t
Thallium 16 mg/t
Total Organic Carbon 78.5 mg/t
Uranium 94 mg/t
Vanadium 263.1 mg/l
Zinc 641 mg/t
pH 1.83 s.u.
pe"20.2
temperatureC 9.9 'C
"PHREEQC adjusts the initial concentrations according to the total mass of solutes;as a result.
all input values were converted from mg/l to mol/kgw (moles per kg of water).
b Value allowed to adjust until redox equilibrium is established.
C Value not measured but assumed equal to the average daily air temperature between 1932 and 1988.
Table 8-6.Se,ected results from chemicalextractions of crushed ~edrcck in addition 10 rr:easurements ofacid·r.eu!";lization ~otenl'al.
leachale solulion rcck dry-bulk densitY'porositY'HFOe~tracled'HFO eXI'i'cled ANp·ANPWell[0and core depth Vadose Zone ANALYTE HFO precici:ated HFOto:al
(ft)HydrostratigraphicUr,;~'(mg/L)(L)(kg)(kg I m')(-)(mg rock f kg rock)(gI kg solulio")(g{kgsolution)(mo[esf kg solulion)(g CaCO,I kg rcck)(moles I kg so[uticn)
MW·30 37.5-38.0 top Iron.dissolved 295 0.'0.01 1978 0.199 4701.41 46.73 1.70 0.544 ,0.099
MW-30 43.0·43.2 '"Iron.diSsolved 38.3 0.'0.01 2023 0.264 610.39 4.68 1.70 0.072 ,0.077
MW-30 43.2·43.5 '"Iron.diSSOlved 25.3 0.'0.01 2023 0.264 403.21 3.09 1.70 0.054 0 0.000
MW·23 53.0.53.5 middle Iren.dissolved 30'0.'0.Q1 2025 0.184 4844.84 53.35 3.54 0.639 ,0.440
MW_2374.0_74.3 hallam Iron.dissolved 1!:U 0.'0.01 2329 0.122 304.40 5.81 0.00 0.065 0 0.000
•Dueto Ihere spatialproximity.model oulput for the three "top"vadose zone hydroSiratigraphic urlilswereaveragedinto one value.
b Dry-bulk density(:::>b)and porosity(n)data takerl from Daniel B.Stephens &Associates (2007).Vaiue ofR>and nfor MW-30 43.0-43.2and 43.2-43.5representcorrectedvalue aftervolume charlge.
<For ronverslonfrom massofFe to massofHFOthe assumed stoichiometry offerrihydrite was Fe:;.OJ:H20 with amolecular weight of 89 g/mol (Dzombak andMoret 1990).
•Acid-rleutralizationpolenlial(AN?)value of 1 9 CaCQper kg ofrock measured at the level ofdetection anda value of0indicatesthe ana1ytewas not detected.
Table 8-7.Selected water-quality from geochemicalmodeling oftaiIings-porewaters during neutralization with underlying bedrockand surface~complexation with HFO
Surface-complexation PHREEQC Vadose Zone Ionic strength CO2(g)partial pH po calcium sulfate total carbon total uranium uranium(VI)uranyl
model Iteration H drostrati ra hlc Unit ressure s.u.molal molal molal mil molal molal
IC IC 1.37 10'.7 1.83 ZO.15 9.09E-03 6.70E-01 6.48E-03 3.91 E-04 3.91E-04 7,3ZE-06
Dzombak and Morel Reaction 1 top 1.42 10.20 5.39 15.51 5.55E-03 5.97E-01 4.86E·04 5.44E-06 5.44E-06 8.48E-08
Dzombak and Morel Reaction 2 middle 1.14 10-20 7.50 12.92 6.12E-03 4.45E-01 1.17E-02 3.37E-06 3.37E-06 2.54E-14
Dzombak and Morel Reaction 3 bottom 1.35 10.20 1.92 19.75 6.12E-03 6.65E-01 3.96E-04 3.91 E-04 3.91E-04 7.43E-06
Table Bv 8.Speciation oftailings-pore waters after equilibration with calcite and complexation with HFO for the Dzombak and More!(1990)modef.
Surtace-complexat'lon
mode!PHREEQC Iteration Vadose Zone Hydrostratigraphic Unit
CazUOz(C03h CaUOz(C03h?U02(C6VUoz(cC);j;:T-uo;c°3 ---~
(%)(%)(%)(%)(%)(%)
Dzombak and More!
Dzombak and Morel
Dzombak and Morel
Reaction 1
Reaction 2
Reaction 3
top
middle
bollom
84.00 2.64 1.10 12.22
2.04
0.01
1.56
7.53 x 10.7
1.90
Surface-campiexation
model PHREEQC lteration Vadose Zone Hydrostratigraphic Unit
U02S04 U02(S04hT U02(S04)~:4 ---UOZN03+-ijO---;F+U02HAs04
(%)(%)(%)(%) (%)(%)
Dzombak and Morel
Dzombak and Morel
Dzombak and Morel
Reaction 1
Reaction 2
Reaction 3
top
middle
bottom
42.37
46.01
45.29
48.44
0.8
0.98
0.29
0.35
1.64
1.78
2.49
0.01
aSubset of speciation results presented.Blank values represent values less than 0.01 %
Table BRg.Calculated distribution (K:)coefficients and retardation factors of uranium forthe Dzombak and Morel (1 990)surtace~complexationmodel.
Suriace-complexation
model
PHREEQC
Iteration
Vadose Zone
Hydrostratigraphic Unit
total uranium (C;-Cr)/Cj mass of rock volume of H20 a Pbb eC Kd R
(molal)(-)(mg)(mL)(mg/cm')(-)(mL/mg)(-)
Dzombak and Morel
Dzombak and Morel
Dzombak and Morel
IC
Reaction 1
Reaction 2
Reaction 3
IC
top
middle
bottom
3.91 E-04 1009
5.44E-06 7.09E+01 8.424E+06 1007
3.37E-06 1.15E+02 1.101E+07 1000
3.91 E-04 2.56E-04 1.909E+07 1010
1980
2030
2330
0.067
0.089
0.121
0.00847
0.0104
o
251
239
1
aFor conversion 1 L assumed equal to 1 kg.
b Dry-bulk density (Pb)taken from Daniel 8.Stephens &Associates (2007).
CAverage vofumetric~watercontent of the underlying vadose zone units were predicted with the HYDRUS-1D base-case scenario for Cells 2 and 3.
Table 8-10.White Mesa Mill vadose zone distribution (~)coefficients and retardation factors (R)for selected contaminants present in the tailings-pore fluidS'·~.
Arsenic Beryllium Cadmium Chromium Cobalt Copper Fluorine'Iron'Le3d M3n~3neSC'Mercury Molyhdenum Nickel Selenium Silver Sulfate<Thallium Uranium V3nadium Zinc
V3doseZ<lnc Kd Kd Kd Kd Kd Kd Krt K~Kd Kd K~K~Kd Kd Kd Kd Kd K~Kd Kd
lIydrostratieraphie Cnil (Ilkg) (lIkg)(Ilkg)(Uk!!:)(Ilkg)(lIke)(like)(llkg) (likg)(lfkll)(llkg)(Iikg)(I/kg)(llkg)(11k!!:)(1/kg)(Ilk!!:)(lIkg) (Iikg)(l/kg)
top 7.19 82.1 0.001 0.557 0.000 4.13 0.000 0.000 9048 0.001 0.000 0.014 0.005 0.015 0.000 0.002 0.000 8047 0.000 0.009
middle 7094 72]40 1.033 4.90 0.1 15 1220 0.0003 0.000 2197 0.901 0.1100 0.663 1.380 0.015 0.000 0.003 0.000 1004 559 I1.3
bottom 0.119 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 o.oon 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000
Vadose Zone R R R R R R R R R R R R R R R R R R R R
r·hdroslr3Ii<>raphic Unit H ( )(--)H ( )H ( )(--)H ( )H () ( )H (--)(--)H ( )H (--)
top 213 2428 1.02 17 1.00 123 1.00 1.00 281 1.02 1.00 1.41 l.l4 1.46 1.00 1.07 1.00 251 1.00 1.26
middle 161804 1645434 25 113 3.63 27822 1.01 1.00 50105 22 1.00 16 32 1.34 1.00 1.07 1.00 239 12744 260
bottom 3.30 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.01 1.00 1.00 1.00 LOG 1.00 1.00
,Methodoiogyand assumptions used to determinesorption (oeffieients arc described in Appendix B.
oAveragcvolumetric-water contentofthe underlying vadosezone units were predicted with the HYDRUS-]D base-case scenario for Cells 2 and 3.
<Sorption coefficients for fluorine,manganese,and sulfate were corrected to account for precipitation offluorite,pyrolusite,and gypsum/barite,respectively.
Table 8-11.Saturation indices (SI)for the tailingsNpore waters and equilibrated solutions predicted for the While Mesa Mill vadose zone hydrostratigraphic units3.
Vadose Zone Calcite Barite Gypsum Anhydrite Amorphous HFO Goethite Amorphous AI-hydroxide Gibbsite Fluorite Pyrolusite Carnotife Tyuyamunite
Hydrostratigraphic CaS04 Fe(OHhc3)AI(OH)3(a)AI(OH),CaFz MnOz KUOZV04 Ca(UOZh(V04)zUnitCaC03BaS04CaS04·2HzO FeOOH
initial condition -9.98 1.18 0.17 -0.06 -3.83 1.51 -10.56 -7.73 -2.21 0.29 -3.98 -10.85
lOP -4.27 0 0 -0.23 5.11 10.45 0.09 2.92 -2.35 0 2.49 1.88
middle 0 0 0 -0.23 7.09 12.43 3.54 6.38 0 0 N1.72 -6.52
bottom -11.19 0 0 -0.23 -3.49 1.84 -10.30 -7.47 -2.38 -0.18 -3.70 -10.48
aA SI >0 indicates mineral precipitation;a SI <0 indicates mineral dissolution;and a SI =0 indicates equilibrium conditions.
HFO is equal to hydrousNferric oxide
Attachment 1
Laboratory data for hydrous-ferric oxidc chemical extraction and acid-ncutralization tests
on selected core samples ofthe White Mesa Mill bedrock vadose zone
ACZ Laboratories,Inc.
2773 Down/li11 Drive Steamboat Springs,CO 80487 (fJOG)334-5493
April 27,2007
Report to:
Doug Oliver
MWH America's Inc.
10619 S.Jordan Gateway Suite 100
Salt Lake City,UT 84095
cc:Ryan Jakubowski
Project ID:1004-A0002-87430-0M/
ACZ Project ID:L62140
Doug Oliver:
Bill to:
Accounts Payable
MWH America's Inc.
P.O.Box 6610
Broomfield,CO 80021
Enclosed are the analytical results for sample(s)submitted to ACZ Laboratories,Inc.(ACZ)on April 20,2007.
This project has been assigned to ACZ's project number,L62140.Please reference this number in all future
inquiries.
All analyses were performed according to ACZ's Quality Assurance Plan,version 11.0.The enclosed results
relate only to the samples received under L62140.Each section of this report has been reviewed and approved
by the appropriate Laboratory Supervisor,or a qualified substitute.
Except as noted,the test resuits for the methods and parameters listed on ACZ's current NELAC certificate
letter (#ACZ)meet all requirements of NELAC.
This report shall be used or copied only in its entirety.ACZ is not responsible for the consequences arising
from the use of a partial report.
All samples and sub-samples associated with this project will be disposed of after May 27,2007.If the samples
are determined to be hazardous,additional charges apply for disposal (typically less than $1 O/sample).If you
would like the samples to be held longer than ACZ's stated policy or to be returned,please contact your Project
Manager or Customer Service Representative for further details and associated costs.ACZ retains analytical
reports for five years.
If you have any questions or other needs,please contact your Project Manager.
27/Apr/07
TOil)'AntJlek,Project Manager,has reviewed and approved this report in its entirety.
REPAD.01.06.05.01 I1062140:Page I of 171
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project ID:
Sample ID:
1004-A0002-87430-0MI
MW-30 37.5-38.0
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140-01
04120107 00:00
04120107
Leachate
Metals Analysis
~~m!II:!JJ~•.I%.~~·l'ma~
Aluminum.dissolved M200.71ep 137 mg/L 0.03 0.2 04/25/0721:09 djl
Calcium,dissolved M200.7 lep 53.5 mg/L 0.2 1 04/25/070:40 djl
Iron,dissolved M200.71ep 295 mg/L 0.02 0.05 04/25/0721:09 djl
Magnesium,dissolved M200.71CP 59.6 mg/L 0.2 1 04/25/070:40 dj!
Manganese,dissolved M200.71CP 8.440 mg/L 0.005 0.03 04/25/070:40 djt
Uranium,dissolved M200.81CP~MS 0.0156 mg/L 0.00010.0005 04/24/071:15 scp
REPIN.02.06.0S.01 •Please refer /0 Qualifier Reports for detail.
L62140:Page 2 of 17
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
MWH America's Inc.
Project ID:1004-A0002-87430-0MI
Sample ID:MW-30 43.0-43.2
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140·02
0412010700:00
04120/07
Leachate
Metals Analysis
_~~..~~m~mU'X~f.trtfg·91·Jk"RV~~
Aluminum,dissolved M200.71CP 69.90 mg/L 0.03 0.2 04/25/0721:13 djt
Calcium,dissolved M200.7 ICP 68.4 mg/L 0.2 1 04/25/07 1:01 djt
Iron,dissolved M2Q0.7ICP 38.30 mg/L 0.02 0.05 04/25/0721:13 djl
Magnesium,dissolved M200.7 ICP 32.5 mg/L 0.2 1 04/25/07 1:01 djl
Manganese.dissolved M200.71CP 0.057 mg/L 0.005 0.03 04/25/071:01 djt
Uranium,dissolved M200.8ICP-MS 0.0109 mgiL 0.00010.0005 04/24/071:21 scp
I<EPIN.02.06.05.01 •Plet'lse refer to Qualifier Reports for detail.
I L62140:Pagd of 17 I
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334·5493
MWH America's Inc.
Project 10:1004-A0002-87430-0MI
Sample 10:MW-30 43.2-43.5
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L62140-03
04120107 00:00
04120107
Leachate
Metals Analysis
~&ftIi#fiwrfPJ1~gil;MtD_Wtt.'IDJ1M1&,i!ll]WW1';h Bmw d~
Aluminum,dissolved M200.7 ICP 58.30 mg/L 0.03 0.2 04/25/0721:18 djt
Calcium.dissolved M200.71CP 53.5 mgfl 0.2 1 04/25/071:05 djt
Iron,dissolved M200.7 ICP 25.30 mg/l 0.02 0.05 04/25/0721:18 djt
Magnesium,dissolved M200.71CP 26.1 mg/l 0.2 1 04/25/071:05 djt
Manganese,dissolved M200.71CP 0.070 mg/L 0.005 0.03 04/25/071:05 djl
Uranium,dissolved M200.8ICP-MS 0.0078 mg/L 0.0002 0.001 04/24/071:27 $CP
REPIN.02.06.05.01 •Please refer to Qualifier Reports for detail.
IL62140:page40fl71
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project ID:1004-A0002-87430-0MI
Sample 10:MW-23 53.0-53.5
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L62140-04
04120107 00:00
04120107
Leachate
Metals AnalysIs
~+m~f1¥+'~~~~~l4piH'mjifulBM'lm~jl,jg¥~I"'.'Wi"m~
Aluminum,dissolved M200,7 rep 176 mg/L 0.03 0.2 04/25/0721:30 djt
Calcium.dissolved M200.7 lep 76.5 mgfL 0.2 1 04/25/07 1:09 djt
Iron,dissolved M200.7 lep 304 mg/L 0.02 0.05 04/25/0721 :30 djt
Magnesium,dissolved M200.71CP 106 mgfl 0.2 1 04/25/071:09 djt
Manganese,dissolved M200.71CP 4.370 mg/L 0.005 0.03 04/25/071:09 djt
Uranium,dissolved M200.8ICP-MS 0.0156 mgfL 0.0001 0.0005 04/24/071:45 scp
REPIN.Q2.06,05.01 •Please refer to QualifierReports for detail.
IL62140:Page 5of 17 I
ACZ Laboratories,Inc.
2773 Downhifl Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project 10:1004-A0002-87430-0MI
Sample 10:MW-2374.0-74.3
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L62140-05
04120107 00:00
04120/07
Leachate
Metals Analysis
~~_~"mrm;<nBli'm,tM!j~d·l.it~J..·mi:##M~
Aluminum,dissolved M200.71ep 40.70 mg/l 0.03 0.2 04/25/0721:43 djt
Calcium,dissolved M200.71ep 24.7 mgfl 0.2 1 04125/071:14 djt
Iron,dissolved M200.71CP 19.10 mg/l 0.02 0.05 04/25/0721:43 djt
Magnesium,dissolved M200.71ep 28.4 mgfl 0.2 1 04/25/071:14 djt
Manganese,dissolved M200.71CP 0.069 mg/l 0.005 0.03 04/25/071:14 djt
Uranium,dissolved M200.8 ICP-MS 0.0112 mgfl 0.0001 0.0005 04/24/07 1:50 scp
REPIN.02.06.05.Q1 •Please referto Qualifier Reports for detail.
I L62140:Page 6 of 17 I
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs.CO 80487(800)334-5493
MWH America's Inc.
Project ID:1004-A0002-87430-0MI
Sample ID:MW-2382.5-82.7
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140-06
04120107 00:00
04120107
Leachate
Metals Analysis
_~~~~~~3~#i4irnrt§·yTtTt!fi~ttl·WA'Thi,_~
Aluminum,dissolved M200.71CP 15.20 mgfl 0.03 0.2 04/25/0721:48 djt
Calcium,dissolved M200.7 lCP 11.3 mg/l 0.2 1 04/25/07 1:18 djt
Iron,dissolved M20Q.7 lCP 14.50 mg/L 0.02 0.05 04/25/0721:48 djt
Magnesium,dissolved M200.71CP 12.7 mg/L 0.2 1 04/25/071:18 djl
Manganese,dissolved M200.?lCP 0.049 mg/L 0.005 0.03 04/25/071:18 djt
Uranium,dissolved M200.8 ICP-MS 0.0122 mg/L 0.0001 0.0005 04/24/07 1:56 $CP
REPIN.02.06.05.01 •Please refer to Qualifier Reports for detail.
IL62140:Page 7 of 17 I
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project ID:
Sample ID:
1004-AO002-87430-0MI
MW-2399.8-100.0
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140-07
04120107 00:00
04120107
Leachate
Metals Analysis
DlliruNi~~_irAI;tvMlmlm$61Il$M~I&
Aluminum,dissolved M200.71CP 29.50 mg/L 0.03 0.2
Calcium,dissolved M200.71CP 19.1 mg/L 0.2 1
Iron,dissolved M20Q'?ICP 74.60 mg/L 0.02 0.05
Magnesium,dissolved M200.7 lCP 9.0 mg/L 0.2
Manganese,dissolved M200.7 JCP 0.222 mg/L 0.005 0.03
Uranium,dissolved M200.8ICP-MS 0.0147 mg/L 0.0001 0.0005
H1iUO*M@lJB
04/25/0721:52 djt
04/25/07 1:22 djt
04/25/0721:52 djt
04/25/07 1:22 djt
04/25/07 1:22 djl
04/24/072:14 scp
REPIN.02.06.05.01 •Please refer to Qualifier Reports for detail.
I L62t40:Page 8 of 17 I
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project ID:1004-A0002-87430-0MI
Sample ID:MW-23103.0-103.3
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140·08
04120107 00:00
04120107
Leachate
Metals Analysis
tJl:!fl!lHWP'ff'!ff3fMU!m:i~""~_~.@lf~1tlljl{.r't~t,'1~
Aluminum,dissolved M200.71CP 24.50 mgtL 0.03 0.2 04/25/0721:56 djt
Calcium,dissolved M20Q.7ICP 14.4 mgtL 0.2 1 04/25/071:26 djt
Iron,dissolved M200.71CP 15.50 mgtL 0.02 0.05 04/25/0721:56 djt
Magnesium,dissolved M200.71CP 9.8 mgtL 0.2 04/25/071:26 djt
Manganese,dissolved M200.7 JCP 0.229 mgtL 0.005 0.03 04/25/071:26 djt
Uranium,dissolved M200.8ICP-MS 0.0105 mgtL 0.00010.0005 04/24/072:19 scp
REPIN.02.06.05.01 *Please refer /0 Qualifier Reports for detail.
IL62140:Page 901"t7 I
ACZ Laboratories,Inc.
2773 DownhillDrive Steamboat Springs,CO 80487(800)334·5493
MWH America's Inc.
Project ID:1004-A0002-87430-0MI
Sample ID:MW-23103.0-103.3DUP
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140-09
04120107 00:00
04120107
Leachate
MetalsAnalysis
~m';tIDffm"iW$~J1N1l'ipfEI;'XP
Aluminum,dissolved M20Q.7ICP 23.50 mg/L 0.03 0.2
Calcium,dissolved M200.71CP 12.7 mg/L 0.2 1
Iron,dissolved M200.71CP 15.20 mg/L 0.02 0.05
Magnesium,dissolved M200J ICP 9.4 mg/L 0.2
Manganese,dissolved M200.71CP 0.224 mg/L 0.005 0.03
Uranium,dissolved M200.8 ICP-MS 0.0105 mg/L 0.0001 0.0005
&1·trt_~
04/26/076:12 djt
04f26/Q76:12 djt
04/26/076:12 djt
04/26/076:12 djt
04/26/076:12 djt
04/24/072:25 scp
REPIN.02.06.05.01 •Please referto Qualifier Reports for detail.
IL62140:Page 10 of 171
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project ID:1004-A0002-87430-0MI
Sample ID:PBS
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L62140·10
0412010700:00
04120107
Leachate
Metals Analysis
trolM\:iEL;iii1iiJ5Wlm1fi~mY'fN¥*t~EVt1~a'''imJf¥WfM&!,J.M~lm:~.Mi-f
Aluminum,dissolved M200.71CP 0.15 B mg/L 0.03 0.2 04/261076:16
Calcium,dissolved M200.7 lep 0.2 B mg/L 0.2 1 04/26/076:16
Iron.dissolved M200.71ep 0.04 B mg/L 0,02 0.05 04/26/076:16
Magnesium,dissolved M200.71CP U mg/L 0.2 1 04/26/076:16
Manganese,dissolved M200.7 lep U mg/L 0.005 0.03 04/26/076:16
Uranium,dissolved M200.8ICP-MS U mgfl 0.0001 0.0005 04/24/072:31
~
djt
djt
djt
dj!
djt
scp
HEPIN.02.06.05.01 •Please refer /0 Qualifier Reports for detail.
IL62140:Page 11 of 171
2773 Down/Jill Drive SteamboatSprings,CO 80487 [phone]
ACZ Laboratories,Inc.
Batch
Found
Limit
Lower
MOL
peN/SeN
POL
OC
Rec
I?PD
Upper
Sample
l[_~~_1Bi_ji.~~~~I~Ili,,,~,EEEEEE1il"!!l~EEEilJliI
A distinct sel ofsamples analyzed at a specific lime
Value althe QC Type of interest
Upper limit for RPD,in %.
Lower Recovery limit,in %(except for LeSS,mg/Kg)
Method Detection Limit Same as Minimum Reporting Limi\.Allows for instrument and annual fluctuations.
A number assigned \0 reagents/standards 10 trace to the manufacturer's certificate of analysis
Pr8clkal Quanl'ilalion Limit,lypically 5 limesthe MOL
True Value of the Conlrol Sample or the amount added to the Spike
Amount of the true value or spike added recovered,in %(except for LeSS.mg/Kg)
Relative Percent Difference,calculation used for Duplicate QC Types
Upper F~ecovery Limit,in %(except for LCSS,mgfKg)
Value of the Sample of interest
~~~~~!i~~;",,~~,!l!~~.'~~\!!h:'-'-;llllIlllliii'llilllB1JIII%ljii_,dd iW!
AS Analytical Spike (Post Digestion)LCSWO Laboratory Control Sample,Water Duplicate
ASO Analytical Spike (Post Digestion)Duplicate LFB Laboratory Fortified Blank
GGB Continuing Calibration Blank Lf=M Labomtory Fortified Matrix
GCV Continuing Cafivation Verification standard LFMO laboratory Fortified Matrix Duplicate
IJUP Sample Duplicate IRE Laboratory Reagent Blank
Ica lnitial Calibration Blank MS Matrix Spike
ICV Initial Calibration Verification standard MSO Matrix Spike Duplicate
fCSAB Inter-element Correction Standard -A plus B solutions PBS Prep Blank -Soil
LCSS Laboratory Control Sample -Soil paw Prep Blank -Water
LCSSD Laboratory Control Sample -Soil Duplicate PQV Practical Quantitalion Verification standard
LCSW Laboratory Control Sample -Water SOL Serial Dilution
l"-i'l"'''f&''&''l''l~ii\Th''''''i(01~_';;:{Wl!r%lil~!iW'''''_",,''''':l\\1l;ql'''W!lJ[_¥J\1'',ddididi~ldllli1;"~~diddill~.~".lU1WJi.~..tl.u;~~tittl\)i;-:;4~~~*$lli'i*~~%;~"t'<%,'fhYd@z&1W&W'~~'¥.@ ,•'i?,,-
81anks Verifies that there is no or minimal contamination in the prep method or calibration procedure.
Control Samples Verifies the accuracy of the method,including U1C prep procedure.
Duplicates Verifies the precision of the instrument and/or method.
Spikes/Fortified Matrix Determines samplc matrix interferences,if any.
Standard Verifies the validity of the calibration.
~rl~~~_~~_¥%*~#*~?i4f'i
B An<Jlyte conccntration detected at a value between MOL and POL.
H AnalysiS exceeded method hold time.pH is a field test with an immediate hold time.
U Analyte was analyzed for but not detected at the indicated MOL
ffiWl%'o/._"'li""""~"""''''];~~%~''''''''''''''=~''~'",m'i!@_!'%==_w''''.,,,,,,_@l-_"i!K_-~-"!l.iiq ~~£££MJbJIU£i..k»4l!~R&'~~~~~'W~t~W~4¥Jij.~~Tht._~..~~~·rl
(1)EPA 600/4-83-020.Methods for Chemical Analysis ofWater and Wastcs,March 1883.
(2)EPA 600ff~-93-100.Methods for the Determination of Inorganic Substances in Environmental Samples,August 1993.
(3)EPA 600fR-94-111.Methods for the Determination of Mctals in Environmcntal Samples-Supplement I,May 1994.
(5)EPA SW-846.Test Methods for Evaluating Solid Waste,Third Edition wi1l1 Update Ill,December 1996.
(6)Standard Methods for the Examination of Water and Wastewater,19th edition,1995.
,.
(1)
(2)
(3)
QC results calculated from raw data.Rcsults may vary slightly if the roundeej values are used in the calculations.
Soil,Sludge,and Plant matrices for Inorganic analyses are reported on a dry weight basis.
Animal matricesfor Inorganic analyscs arc reported on an "as receivcd"basis.
;;
REPIN03.02.07.01
IL62140:pagcI20fJ7!
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
MWH America's Inc,ACZ Project 10:L62140
L62140-01 WG223614 Manganese,dissolved M200.71CP M3 Tile accuracyof the spike recovery does not apply because
analyle concen\r<llion in the sample is disproportionsle to
the spike level.The recovery of the method control sample
was acceptable.
l62140-02 WG223614 MangBnese.dissolved M200.71CP M3 The accuracy of the spike recovery does not apply because
analyle concentration in the sample is disproportionate 10
the spike level.The recovery ofthe methodcontrol sample
was acceptable.
L62140-03 WG223639 Aluminum,dissolved M200.71CP M3 The accuracy of 11m spike recovery does nol apply because
analyteconcentration in the sample is disproportionate to
tile spike level.The recovery of the methodcontrol sample
was acceptable.
Iron,dissolved M200.71CP M3 The accuracyof the spike recovery does not apply because
analyte concentration in the sample is disproportionate to
the spike level.The recovery of the method control sample
was acceptable.
WG223614 Manganese,dissolved M200.71CP M3 The accuracyof the spike recovery does not apply because
analyte concentration in the sample is disproportionate to
the spike level.The recovery of!ile method control sample
was acceptable.
L62140-04 WG223639 Aluminum,dissolved M200.7 ICP M3 The accuracyof the spike recovery does not apply because
analyteconcentration in the sample is disproportionate to
the spike level.Tile recovery of the methodcontrol sample
was acceptnble.
Iron,dissolved M200.71CP M3 The accuracyof the spike recovery does not apply because
nnalyte concentr,Jtion 'm the sample isdisproportionate to
the spike level.The recovery ofthe method control sample
was acceptable.
WG223614 Manganese,dissolved M200.71CP M3 The 8ccuracy of the spike recovery does not apply bec(J.use
analyte concentrnlion in the sample is disproportionate to
the spike level.The recovery ofthe method control sample
was acceptable.
L62140-05 WG223639 Aluminum,dissolved M200.7 ICP M3 The accuracyof the spike recovery does not apply because
nnalyteconcentration in tile sample is disproportionate to
the spike level.The recovery of the methodcontrol sample
was acccptnble.
Iron,dissolved M200.71CP M3 The accuracy of the spike recovery does not apply because
analyte concentration in tM sample is disproportionate to
H18 spike level.The recovery ofthe melllOd control sample
wasacceptable.
WG223614 Manganese,dissolved M200.7 ICP M3 The accuracy of the spike recovery does not apply because
analyte concentration in the sample is disproportionate to
the spike level.The recovery ofthe method control sample
was acceptable.
l£2140-0£WG223639 Aluminum,dissolved M200.71CP M3 The accuracyof the spike recovery does not apply because
analyte concentration in the sample is disproportionate to
the spike level.The recovery of the methodcontrol sample
was acceptable.
Iron,dissolved M200.71CP M3 The accuracy of the spike recovery does not apply because
analyte concentration in the sample is disproportionate to
the spike level.The recovery ofthe metllod control sample
was acceptable,
WG223614 Manganese,dissolved M200.7 ICP M3 The accuracy of the spike recovery does not apply because
analyte concentration in the sample is disproportionate to
the spike level.The recovery ofthe method control sample
was au;eptable.
REPAD.15.06.05.01
IL62J40:Page 13 of 171
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
MWH America's Inc.ACZ Project ID:L62140
l62140·07 WG223639 Aluminum,dissolved M200.71CP M3 The accuracy of the spike recovery does not apply becau
analyte concentration in 1l1C sample is disproportionate to
the spike level.The recovery 01 the method control sarnpl(
was acceptable.
Iron,dissolved M200.7 ICP M3 The accuracy of the spike recovery does nol apply becau
analyte concentration in the sample is disproportionate to
the spike level.The recovery 01 the method control sampl(
was acceptable.
WG223614 Manganese,dissolved M20Q.7ICP M3 The accuracy of the spike recovery does '101 apply becau
analyte concentration in Ihc sample is disproportionate \0
1I1e spike level.The recovery 01 the method control sampll
was acceptable.
l62140-08 WG223639 Aluminum,dissolved M200.7 ICP M3 The accllr<lcy ofthe spike recovr:ry does not apply bec3u
analyte concentration in Hm sample is disproportionate to
the spike level.The recove,,!of the method conlrol samp!l
was acceptable.
Iron,dissolw,'M2QQ.7 ICP M3 The aCCUr<lcy ofthe spike recovery does not apply becau
analyte concentration in the sample is disproportionate to
the spike level.The recovery of the method conirol samplr
was aCG0ptable.
WG223614 MannanesE-(·'~·olved M200.71CP M3 The accuracyof the spike recovery does not apply becau
analyte concentration in the sample is disproportionate to
the spike level.The recovery ollbe method conlrol sampl,
was acceptable,
HEPAO.15.06.05.01
L62140:Page 14 of 17
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
MWH America's Inc.ACZ Project ID:L62140
Metals Analysis
~~~fWi'"fflf,fif~mi'li~;rif1i!~~I.1_~~~'""'-_",,·.,,;Y.1gt_f._'!!l'%P~~~~~~':'{\WA$~*y=~=~~w.J,%@-~:0L~»Mf~~~~~~~=.'"1lO~~
Aluminum,dissolved M200.7 ICP
Calcium,dissolved M20Q.7ICP
Iron,dissolved M200.71CP
Magnesium.dissolved M200.71CP
Manganese.dissolved M200.7 ICP
Uranium,dissolved M200.8 ICP-MS
REPAD.05.06.05.01
11.62140:Page 15 of 171
~Ll_"I\LDbL\~OO'l--VJ cxhO
Core Samples from White Mesa near Blanding UT shipped to ACZ for Leach Testing
Contact Info:Doug Oliver·MWH (801-617-3224)or Ryan Jakubowski in Steamboat (970-879-6260)
Subcontract Number:10Q4-AOOO2-8743Cl-OMlMSA COl
••,--"'.,,,,..•"'~."'.='='"'':_;."=",,,,,,-.:'='-::';"':'.----_.•."-'••~-,",,'--;:-.:~-_."••.-._.'.
"~N...'?
.~.,•.~-".~-~¥"''''.,-••-.
Depth
LoclD (feet bgs)
MW-30 37.5-38.0
MW-30 43.0-432
MW-30 43.2-43.5
MW-23 53.0-53.5
MW-23 74.0-74.3
MW·23 82.5-82.7
MW-23 99.8-100.0
MW-23 103.Cl-l03.3 I
P1E'<i.se COl'1tolt t KYrllf\;f-y[)~V)C'C'J
~Q\W\~\e fief.A\:;Q U?Y1h Gt-KyotV\
Vlv'\V\5~J\,-sC\W\f \~
Th¢lI\~.J
.::uo~
r!I"Y C\...>SlSh,V1 a:\J,'1i,
-h>r\'tk \A f d;VI)!
c:z:,o l.i .q.0-=1 \1:d-.O
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
Doug Oliver
MWH America's Inc.
10619 S.Jordan Gateway Suite 100
Saft L<lke City,UT 84095
Page 1of2
4/20/2007
Matrix:leachate 96 Hour HH Extraction Leachates for metals
Metals Analysis
Aluminum,dissolved
Calcium,dissolved
Iron,dissolved
Magnesium,dissolved
Manganese,dissolved
Uranium,dissolved
REPAO.09.06.05.01
M200.71CP
M200.71CP
M200.71CP
M200.71CP
M200.71CP
M200.8 lCP-MS
0.03 mg/l
0.2 mg/L
0.02 mg/L
0.2 mg/L
0.005 mgfL
0.0001 mg/l
CosUSample:
01
$8.00
$8.00
$8.00
$8.00
$8.00
$38.00
$78.00
PI
L62140:Page 17 of 17
,
Analytical Method:WG -------ACZ Laboratories,Inc.
Analyst:<;;;1...5
Start Oaoo:_
End Oate:_
('00 ~....}-,W4k<t-(k.
ACZ 10 iDs 17~d<,j f.-.i.-<.?f/"'-
C «_/J £..-"C f":':':9'1;0<)"1i-<I oJ-,.-<(i w.<-L -n ,-_.t/:.I,;
..'f'1 '<:-",',
'i?1Z.>14I!f~GJ'~.r;\'",,>,"4 <J'~'5,)'1 ~,..~~~,{,?-flIo-,o
II_/::-/<;/?-_(-J
-J -2
~~-~
-'r -'1-,-)
~/~
-'].1/-7-
-y -~
-IJD y.-'1
/'../.......
//1/II
~/1 1//
Comments:¢(;of(54....,,.,;'/?ole,J,../c;elf1M c!rt.Z.y ,
f?i>....'5 3 ()'0 '-~,.-f',(",.",......./<-<--../1..."-0.<fl~~
7 '5To-=j-o '-1/(,./.J>.c.r!z..b1-2-'7
Page __of __
h It.s~I'I,.v>--........IIf-!.>o/....!-I<;...,r--/
Bench Sheet Form.XLS.0811512003
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
August 10,2007
Report to:
John Mahoney
MWH America's Inc.
1801Califomia Street Suite 2600
Oenver,CO 80202
cc:Ryan Jakubowski
Project 10:
ACZ Project to:L64240
John Mahoney:
Biil to:
Accounts Payable
MWH America's Inc.
PO Box 6610
Broomfield,CO 80021
Enclosed are the analytical results for sample(s)submitted to ACZ Laboratories,Inc.(ACZ)on August 03,
2007.This project has been assigned to ACZ's project number,L64240.Please reference this number in ail
future inquiries.
Ail analyses were performed according to ACZ's Quality Assurance Plan,version 11.0.The enclosed results
relate only to the samples received under L64240.Each section of this report has been reviewed and approved
by the appropriate Laboratory Supervisor,or a qualified substitute.
Except as noted,the test results for the methods and parameters listed on ACZ's current NELAC certificate
letter (#ACZ)meet all requirements of NELAC.
This report shall be used or copied only in its entirety.ACZ is not responsible for the consequences arising
from the use of a partial report.
All samples and sub-samples associated with this project wiil be disposed of after September 10,2007.If Ihe
samples are delermined to be hazardous,additional charges apply for disposal (typically less than
$10/sample).If you would like the samples to be held longer than ACZ's stated policy or to be retumed,please
contact your Project Manager or Customer Service Representative for further details and associated costs.
ACZ retains analytical reports for five years.
Ifyou have any questions or other needs,please contact your Project Manager.
l§:~~27/ApJ107
Tony Antalek,Project Manager,has reviewed and approved this rcpo11 in its cnlircty.
REPAD.01.06.05.01 I L62140:Page 1 of 171
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project 10:
Sample 10:L61917-01
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L64240-01
08103107 09:55
08103107
Soil
Soil Analysis
~~~~~~_lDM~!·+i'l~mB
Acid Neutralization M600/2-78-0541.3 1 t CaC03/Kt 1 5 08/08/0716:22 calc
Potential (calc)
Neutralization M600/2-78-0543.2.3 0.1 B %0.1 0.5 OBI04f079:35 Iwt
Potential as CaC03
REPIN.02.06.05.01 •Please refer to Qualifier Reports for detail.
1.62140:Page 2 of 17
ACZ Laboratories,Inc.
2773 Down/Jill Drive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project 10:
Sample 10:L61917-02
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L64240·02
08103107 09:55
08103107
Soil
Soil Analysis
~;;]$~ifl.__limlt*¥Hi1Nmfl~f8J;'·1[hi.~
Acid Neutralization M600/2-78-054 1.3 I CaC03/Kt 5 08/08/0716:22 calc
Potential (calc)
Neutralization M600/2-78-0543.2.3 0.1 B %0.1 0.5 08/04/0710:07 lwt
PolenUal as CaC03
Soil Preparation
~1I!J'~\ljlj1W~~Tmrrl1i,,;:_mt::'nr~~!Mj .!j't&'it¥'l~
Crush and Pulverize USDA No.1,1972 08/03/0714:03 lwl
REPIN.02.06.05.01 •Please refer to QualifierReports for detail.
IL62140:Page}of 17 I
ACZ Laboratories,Inc.
2773 Downhilf Drive Steamboat Springs,CO 80487(800)334-5493
L61917-03
MWH America's Inc.
Project 10:
Sample 10:
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L64240-03
08/03/0709:55
08/03/07
Soil
Iwl0.5 08/04/07 10:390.1%u
~S~O~i1~A~na~,y~siiSil~~~lUl~!1IDml!l~~~~~~1l!1f!'Ij!11!IT!t.,.e§fmjl1lllm'r .1 "~i1.%i!ilJ}~I\i.1Pi1'l*tlMl""1!'I.~
Acid Neutralization M600/2~78-054 1.3 0 t CaCQ3/Kt 1 5 08/08/0?16:22 calc
Potential (calc)
Neutralization M600/2-78-0543.2.3
Potential as CaCQ3
Soil Preparation
~ttwk~1mmlRi&ii\Y~D~W1FW@§l~J'*M~~~
Crush and Pulverize USDA No.1,1972 08/03/0?14;07 lwt
REPIN.02.06.05.01 ~Please refer to Qualifier Reports for detail.
I L62140:Page 4 of J7
ACZ Laboratories,Inc.
2773 OownhilfDrive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project ID:
Sample ID:L61917-04
ACZ Sample ID:
Date Sampled:
Date Received:
Sample Matrix:
L64240-04
0810310709:55
08103107
Soil
Soil Analysis
~\iiJfi!II9*,8(11ill)l1!"I;IJ~ITt!m·ii\'iJllJli-&!·j'i&J.lIlI!iiii·tJi,;!~
Acid Neutralization M60012·78-0541.3 4 I CaC03/Kt 1 5 08/08/0716:23 calc
Potential (calc)
Neutralization M600/2-78-054 3.2.3 0.4 B %0.1 0.5 08/04/07 11 :11 Iwl
Potential as CaC03
REPIN.02.06.05.01 •Please refer to Qualifier Reports for detail.
11.62140:PageSafl7
ACZ Laboratories,Inc.
2773 DownhillDrive Steamboat Springs,CO 80487(800)334-5493
MWH America's Inc.
Project 10:
Sample 10:L61917-05
ACZ Sample 10:
Date Sampled:
Date Received:
Sample Matrix:
L64240·05
08103107 09:55
08103107
Soil
Soil Analysis
a:wmtllllllltl~W1Jll!¥t~Ml;?l mm_!~[R).~lli~~
Add Neutralization M600/2-78-054 1,3 0 I CaC03/Kt 1 5 08/08/07 16:23 calc
Potential (calc)
Neutra!ization M600/2-78-0543.2.3 U %0.1 0,5 08/04/0711:43 lwt
Potential as CaC03
Soil Preparation
~-~~.4:mJ!iml"j'_lKt.!1l1'Jr.!'!I;j~'iil··11"'.~
Crush and Pulverize USDA No.1,1972 08/03/07 14:15 Iwt
REPIN.02.06.05.01 •Please refer to Qualifier Reports for de/ail.
IL62140:Page 6 of J7 I
2773DownhillOlive Steamboat Springs,CO 80487 [phone]
J~CZ
Balch
Found
Limit
Lower
MOL
peN/SeN
PQL
OC
Rec
RPO
Upper
Sample
Laboratories,Inc.
A distinct set of samples analyzed 81 8 specific lime
Value oftheQC Type of interest
Upper limit for RPD,in %,
Lower Recovery limit,in %(except for LeSS,mg/Kg)
Method Detection Limit Same as Minimum Reporting Limit.Allows for instrumentand annuailluctuations.
A number assigned \0 reagents/standards to trace to the manufacturer's certificate of analysis
Practical Quanlitalion Urnil,lypically 5 limesthe MOL.
True Value of the Control Sample or the amount added \0 the Spike
Amount of the true value or spike added recovered,in %(except for LeSS,mg/Kg)
Relative Percent Difference,calculation used for Duplicate QC Types
Upper Hecovery Limit,in %(except for lCSS,mg/Kg)
Value of the Sample of interest
_iHifii~~t]t M!ti£Ji4 .g..i~.A~)k.
AS Analytical Spike (Post Digestion)I-GSWD laboratory Control Sample -Water Duplicate
ASD Analytical Spike (Post Digestion)Duplicate LFB laboratory Fortified Blank
GGB Continuing Calibration Blank LFM laboratory Fortified Matrix
GGV Continuing Calivation VerifiC8tion st8ndard LFMD laboratory Fortified Matrix Duplicate
OUP Sample Dupticate Lf~B laboratory Reagent Blank
ICB Initial Calibration Btank MS Matrix Spike
ICV Initial Calibration Verification standard MSD Matrix Spike Duplicate
ICSAB Inter-element Correction St(lndard -A plus B solutions PBS Prep Blank -Soil
LCSS laboratory Control Sample -Soil PBW Prep Blank -Water
I-GSSD laboratory Control Sample -Soil Duplicate PQV Practical Quantitation Verification standard
I.GSW laboratory Control Sample -Water SDL Serial Dilution
rn:9~rt't~~I\'~~':':\>.~11~~
Blanks Verifies thClt there is no or minimal contamination in the prep method or calibration procedure.
Control Samples Verifies the accuracy ofthe method,inclUding the prep procedure.
Duplicates Verifies the precision of the instrument Clnd/or method.
Spikes/Fortified Matrix Determines sample matrix interferences,if any.
Standard Verifies the validity of the calibration.
~1t~I!S__m!:*;1 .minliF ¥;,rWit_
B Analyte concentration detected at a value between MOL and PQL.
H Analysis exceeded method 110ld lime.pH is a field test with an immediate hold time.
U Analyte was analyzed for but not detected at the indicated MOL
l'W?l>I&i',\i\1:_".""'.''~_1%$ii&@%@\_M~~tt[:~~A~~~'·'~~;)"g .~.~~~~
(1)EPA 600/4-83-020.Methods for Chemical Analysis ofWater and Wastes,March 1983.
(2)EPA 600/R-93-100.Methods for the Determination of Inorganic Substances in Environmental Samples,August 1993.
(3)EPA 600/R-94-111.Methods for the Determinallon of Metals in Environmental Samples -Supplement I,May 1994.
(5)EPA SW-846.Test Methods for Evaluating Solid Waste,Third Edition with Update Ill,December 1996.
(6)Standard Methods for the Examination of Water and Wastewater,19th edition,1995.
~~A.¥+M+,tAW L Jppmn;1 5:f?;1*91.
(1)QC results calculated from raw data.Results may vary sligtltly if tile rounded values are used in the calculations.
(2)Soil,Sltldge,and Plant matrices for Inorganic analyses are reported on a (Jry weight basis.
(3)Animal matrices for Inorganic analyses are reported on an "as received"basis.
REPIN03.02.07.01
IL62140:Page 7 of 17 I
ACZ Laboratories,Inc.
2773 DownhillDrive Steamboat Springs,CO 80487 [phone]
MWH America's Inc.ACZ Project 10:L64240
L6424Q·Q1 WG229660 Neutralization Potential as CaC03 11.1600/2-78-054 3.2.3 RA Relative Percent Difference (RPO)was not used lor dala
validation because the sampleconcenlwtion is too lOw for
accurateevaluation «10x MOL).
l64240·02 WG229660 Neutralization Potential as C8C03 11.1600/2-78-054 3.2.3 RA Relative Percent Difference (RPD)was not used lor dala
validation because the smnpleconcentration is too lOw for
accurate evaluation «10x MOL).
l64240·03 WG229660 Neutralization Polenli81 as CaC03 M600f2-78-0543.2.3 RA Relative Percent Difference (RPD)WflS nol used for dala
validation because the sampleconcentration is too low for
accurate evaluation «10x MOL).
L64240-04 WG229660 Nr:utralizHtion Potential as CaC03 M600f2-78-054 3.2.3 RA Relative Percent Difference (RPD)was not used for data
validation because the sampleconcentration is too lowfor
accurate evaluation «10x MOL).
L64240-05 WG229660 Neutralization Potential as CaC03 M600f2-78-0543,2.3 RA Relative Percent Difference (RPD)was not used for data
validation because the sampleconcentration is too lowfor
accurate evaluation «10x MOL).
HEPAD.15.06.05.01
IL62140:Page 8of 17 I
ACZ Laboratories,Inc.
2773Downhill Drive Steamboat Springs,CO 80487 (800)334·5493
MWH America's Inc.ACZ Project 10:L64240
Soil Analysis
~~Y~~.B!!Il!W,a.~
Neutralization Potential <IS CaC03 M600/2-78-0543.2.3
REPAD.05.06.05.01
I L62140:Pagc90fl71
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 [phone]
MWH America's Inc.ACZ Project ID:
Date Received:
Received By:
Date Printed:
L64240
8/3/2007
8/3/2007
1)Does this project require special handling procedures such as CLP protocol?
2)Are the custody seals on the cooler intact?
3)Are the custody seals on the sample containers intact?
4)Is there a Chain ofCustody or other directive shipping papers present?
5)Is the Chain of Custody complete?
6)Is the Chain of Custody in agreement with the samples received?
7)Is there enough sample for all requested analyses?
8)Are al!samples within holding times for requested analyses?
9)Were all sample containers received intact?
10)Are the temperature blanks present?
11)Are the trip blanks (VOA and/or Cyanide)present?
12)Are samples requiring no headspace,headspace free?
13)Do the samples that requiH';F'r','<i~:n Soils Permit have one?
YES
x
x
x
x
x
x
NO NA
x
x
x
x
x
x
x
N/A
N/A
Cooler ld Temp lOG)Rad I~R/hr)
NA4111 22.3 15
Client must contact ACZ Project Manager if analysis should not proceed for
samples received outside of thermal preservation acceptance criteria.
REPAD.03.".00.0'
L62t40:Page 100ft7
ACZ Laboratories,Inc.
2773 Downhill Drive Steamboat Springs,CO 80487 (800)334·5493
L64240
8/3/2007
MWH America's Inc,ACZ Project 10:
Date Received:
Received By:
V:"~'>;C"'<"":D!'l~"1:"~'''''-;{''·);''W;}~·'l;>m0.iC·''S''sv~~<1S~~fI~~"l;.'1S!''''Y%>~fl~~~§!t,o;,'''''~!if',~'!>:flP''~w,,}1\w·';'''"~m'Ei~~~~R{~~~~i;f~~lMJIJMi~~lnllY1iUIl&7~J1wj,J~\~lt~1bii_it[j.%1t\~~.twA:;'~'t~.~~~~~~~
SAMPLE CLIENT 10 R<2 G<2 BK<2 Y<2 YG<2 B<2 0<2 T >12 N/A RAO 10 I
L64240-01 L61917-01 X IIlli1
must be <250 ~RJhr
L64240-02 L61917-02 X Ifill
f'L6='4"2:-:4::0_c:0:;3-+Lc;6:-:,:;9:',7:-_0::3:-------j--t---+--I--+--j--t---+--I-'::x:-f---jlfill
1.64240-04 1.61917-04 X Ifill
L64240-05 L61917-05 X Ifill~~~~~~Tft1Wfi~i'~)\1i]~,;1rr~~'S~r~~~1~~~.!.Et~~fu~~!%~~ft:~%{~~ti0mll~i~~>@;w.fftw.~~~~f~~~:~~J2ft~~t~Jt,:~~LkKWJ:M_.Jill.,%t~SWi&'t:4.':',':i<~~~'i=",.M~~lit;:N.;"vk§.jm';;;*4J1~':$Y.,wm.<K.wM';:'%:k\mMK~•.-"_'»~
Abbreviation Description Container Type PreservativcfLimits
R Raw/Nitric RED pH must be <2
B Filtered/Sulfuric BLUE pH must be <2
BK Filtered/Nitric BLACK pH must be < 2
G Filtered/Nitric GREEN pH must be <2
o Raw/Sulfuric ORANGE pH must be < 2
P Haw/NaOH PURPLE pH must be >12 ~
T Raw/NaOH~Zjnc Acetate TAN pH must be >12
Y Raw/Sulfuric YELLOW pH must be <2
YG Raw/Sulfuric YELLOW GLASS pH must be <2
N/A No preservative needed Not applicable
RAD GammafBeta dose rate Not applicable
~pH check perlormed by analyst prior to sample preparation
Sample IDs r~eviewed By:
f~EPAD.03.11.00.01
L62140:Page 11 of 17
ACZ Laboratories,Inc.LLJ\8l4 0
Steamboat Springs,CO 80487 [phone]
Name:E-mail:
Com an Tele hone:
Invoice to:.
Name:Address:
Com an
YES
NO
Iiance testin
E-mail:L:T...e...le=h...o...n...e:.--.-_-._-1
If sample(s)received past holding time (HT),or if insufficient HT remains to complete
analysis before expiration,shall ACZ proceed with requested short HT analyses?
If "NO"then ACZ will contact client for further instruction.If neither "YES"nor "NO"
is indicated,ACZ will proceed with the requested anal ses,even if HT is expired,and data will be••
-03
-0'1
-o};
SW (Surface Water).GW (Ground Water).WW (Waste Water).OW (Drinking Water).SL (Sludge).SO (Soil).OL (Oil).Other
PAGE
of
FRMADOSO.03.0S.02 White -Return with sample.Yellow -Retain for your records.,L62J40:Page 12 of 171