&EPA
United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P.O. Box 15027
Las Vegas NV 89114
EPA-600/7-80-132
June 1980
Research and Development
Monitoring Groundwater
Quality:
The Impact of In Situ
Oil Shale Retorting
Interagency Energy-
Environment Research
and Development
Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad categories
were established to facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously planned to foster
technology transfer and a maximum interface in related fields. The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY—ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the effort
funded under the 17-agency Federal Energy/Environment Research and Development
Program. These studies relate to EPA'S mission to protect the public health and welfare
from adverse effects of pollutants associated with energy systems. The goal of the Pro-
gram is to assure the rapid development of domestic energy supplies in an environ-
mentally-compatible manner by providing the necessary environmental data and
control technology. Investigations include analyses of the transport of energy-related
pollutants and their health and ecological effects; assessments of, and development of,
control technologies for energy systems; and integrated assessments of a wide range
of energy-related environmental issues.
This document is available to the public through the National Technical Information
Service, Springfield, Virginia 22161
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EPA-600/7-80-132
June 198Q
MONITORING GROUNDWATER QUALITY:
The Impact of
In Situ Oil Shale Retorting
Edited by:
G.C. Slawson,Jr.
General Electric Company—TEMPO
Center for Advanced Studies
Santa Barbara, California 93102
Contract No. 68-03-2449
Project Officer
Leslie G. McMillion
Environmental Monitoring Systems Laboratory
t^as Vegas, Nevada 89114
ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring Systems
Laboratory—Las Vegas, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or rec-
ommendation for use.
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FOREWORD
Protection of the environment requires effective regulatory actions
based on sound technical and scientific data. The data must include the
quantitative description and linking of pollutant sources, transport mech-
anisms, interactions, and resulting effects on man and his environment.
Because of the complexities involved, assessment of exposure to specific
pollutants in the environment requires a total systems approach that tran-
scends the media of air, water, and land. The Environmental Monitoring
Systems Laboratory at Las Vegas contributes to the formation and enhancement
of a sound monitoring-data base for exposure assessment through programs de-
signed to:
• Develop and optimize systems and strategies for monitoring pol-
lutants and their impact on the environment
• Demonstrate new monitoring systems and technologies by applying
them to fulfill special monitoring needs of the Agency's operat-
ing programs.
This report presents the initial phases of a study of design and imple-
mentation of groundwater quality monitoring programs for modified in-situ
(MIS) oil shale retorting in the Western United States. The development of
preliminary priority ranking of potential pollution sources and the pollu-
tants associated with these sources is presented. Currently proposed MIS
monitoring programs are reviewed. Key issues and uncertainties with regard
to groundwater quality impacts and monitoring are identified.
The results of this report are the initial segment of a design and test-
ing program. Further testing and evaluation in the following program segment
(Phase II) will be utilized to develop recommendations for the cost-effective
monitoring of MIS retorts. This study has considered the type of MIS opera-
tion proposed for Federal Prototype Lease Tracts C-a and C-b in western Colo-
rado. These proposed developments form the case study evaluations included
for this report, although the specific design of monitoring programs for
these development tracts is not the purpose of this research project.
The research program, of which this report is part, is intended to pro-
vide technical information and a planning format for the design of ground-
water quality monitoring programs for this type of oil 'shale development.
The study results may be used by i-ndustrial developers and their consultants,
as well as by the various local, State, and Federal agencies with responsi-
bilities in environmental monitoring and planning.
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Further information on this study and on the subject of groundwater
quality monitoring in general can be obtained by contacting the Environmental
Monitoring Systems Laboratory, U.S. Environmental Protection Agency, Las
Vegas, Nevada.
Glenn E. Schweitzer
Director
Environmental Monitoring Systems Laboratory
Las Vegas
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PREFACE
General Electric--TEMPO, Center for Advanced Studies, is conducting a
3-year program dealing with the design of groundwater quality monitoring
programs for western oil shale. The type of oil shale development being
evaluated in this study is MIS retorting as presently proposed for Federal
Prototype Lease Tracts C-a and C-b in western Colorado. This study focuses
specifically on the monitoring of in-situ retorts and is following a stepwise
monitoring methodology developed by TEMPO.
This report represents the initial phase of this research program. The
goals of this initial phase were to:
• Review MIS development with regard to potential impacts on
groundwater quality and review current MIS monitoring programs
• Use this review to identify the key issues, uncertainties, and
unknowns with regard to design and implementation of groundwater
quality monitoring programs for MIS retorts.
These items are addressed in this report and provide a basis for Phase II
studies to further investigate and evaluate these points of concern.
The goal of Phase II will be to develop support information in areas of
focus defined during Phase I and to finalize recommendations for monitoring
the groundwater quality impact of MIS retorts. The recommendations will pro-
vide a general evaluation and decision framework for design of monitoring
programs for specific development sites. Procedures will be recommended for
accomplishing the various evaluation tasks (e.g., hydrogeologic characteriza-
tion and pollutant mobility assessment) and for specific monitoring activi-
ties (e.g., well construction and sample collection).
The final product of this research program will be a planning document
which will, provide a technical basis and a methodology for the design of
groundwater quality monitoring programs for oil shale industrial developers
and the various governmental agencies concerned with environmental planning
and protection.
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SUMMARY AND DESIGN RECOMMENDATIONS
INTRODUCTION
This report summarizes and evaluates the data compiled during Phase I of
this research project. The general goals of Phase I were to:
1. Review MIS oil shale retorting with regard to potential impacts
on groundwater quality and review development of currently
operating or proposed MIS monitoring programs on Federal Lease
Tracts C-a and C-b
2. Develop preliminary recommendations for the design and imple-
mentation of groundwater quality monitoring programs for MIS
retorts.
The final goal of this research program is to develop cost-effective
monitoring designs for MIS retorts. Before the issue of cost effectiveness
can be addressed completely, a comprehensive analysis of the current state of
development of MIS monitoring must be completed. This required analysis is
presented in this report.
The Phase I review and assessment has led to the preparation of a pre-
liminary monitoring approach for this new type of industrial development. In
addition, the uncertainties and unknowns that exist with regard to evaluating
and monitoring MIS retorts have been identified. Phase II of this project
has been designed to address these factors and to develop data pertinent to
finalizing a recommended monitoring approach. These final, recommendations
will be based on technical issues, such as identified in this report, and on
supplemental technical and cost data developed during Phase II studies.
GENERAL MONITORING STRATEGY
The basic goals of monitoring are to (1) detect and measure groundwater
flow within the abandoned retort interval and (2) to detect changes in
groundwater quality from waste residuals (e.g., spent shale, retort water)
within the abandoned retort zone.
Because of the nature of MIS retort development and the subsurface lo-
cation of the retorts, a potential exists for contact of groundwaters with
spent shale materials and subsequent leaching of soluble inorganic and or-
ganic constituents from the retort zone. The characteristics and extent of
these potential impacts are highly dependent on site-specific hydrogeologic
conditions (e.g., extent of fracturing, location of aquifers relative to
vi
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retort interval, head relationship between aquifers, etc.). Consideration of
these factors will result in groundwater quality monitoring programs which
are, in detail, defined by site-specific and development-specific features.
There are, however, generic monitoring design and operational procedures
which are recommended for development of programs for specific sites.
The focus of this evaluation and the resulting recommendations is the
MIS retorts. Thus, characterization and monitoring of deep aquifers is the
topic of this summary.
It is the general conclusion of the Phase I assessment that equipment
and evaluation techniques are available which can provide -accurate character-
ization of site-specific hydrogeologic features and hence allow development
of sound groundwater quality monitoring programs. Outlined below are prelim-
inary recommendations for the design and implementation of monitoring pro-
grams. These strategies and methods are appreciably different than approaches
described for the existing MIS tracts (see Section 9). General monitoring
strategy recommendations are as follows:
1. Source-specific orientation. Groundwater quality monitoring
networks should be designed specifically for detecting ground-
water inflow to the abandoned retort zone and related effects
on groundwater quality. Monitoring strategies focusing on
measuring groundwater quality on a large (regional or large
tract) scale cannot be expected to provide for early detection
of potential pollution problems and implementation of environ-
mental control measures. For the most part, existing hydro-
geologic characterization and baseline monitoring programs
have a regional-scale focus.
2. Routine monitoring of selected "indicator" constituents. This
is recommended and is considered more cost effective than the
extensive water quality analysis programs currently imple-
mented. Extensive inorganic and organic analyses are indicated
as a response to impacts detected by such routine monitoring,
but are not needed as part of the routine monitoring program.
3. Relatively small spatialscale. This is related to items 1
and 2. Monitoring well networks should be within and directly
adjacent to abandoned retort fields.
4. Iterative design process. The monitoring design process is
initiated with site exploration and resource evaluation activ-
ities. Hydrogeologic data will continue to be collected dur-
ing the mine and retort construction phases. These data, in
addition to MIS design changes, may necessitate revision of
groundwater quality monitoring designs. Wells used for base-
line studies provide for initial hydrogeologic characteriza-
tion, but may not be adequate for operational monitoring
needs. This is particularly true where baseline programs have
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a regional-scale orientation. An iterative (planning-
implementation-reevalution) procedure to address monitoring
needs is recommended.
A sequence of events coordinating site development and monitoring pro-
gram development is shown below. Recommended approaches include maximum use
of data from site development activities, phased reevalflation of the hydro-
geologic system to design a testing program as well as a monitoring program,
and delay of final monitoring design and implementation to closely follow
retort field operation and phased abandonment. This latter approach allows
maximum use of data from mine development and dewatering activities, as well
as allowing maximum reponse to mine/retort design changes.
This design sequence deals with a recommended approach for work on a new
oil shale tract. Specific recommendations for modification of site develop-
ment and monitoring programs already underway are beyond the scope of this
study, although the evaluation/design process outlined can be used as the
GENERAL SEQUENCING OF IN-SITU SITE DEVELOPMENT
AND RETORT MONITORING PROGRAM
Industrial Development Phase
Exploration/Resource Evaluation
Initial Mine Plan/Retort Design
Dewatering/Mine Development
Retorting
Operation
Monitoring Design Phase
Initial hydrogeo logic
characterization
Design of hydrogeologic test
program
Conduct hydrogeologic test
program
Reevaluation--prel iminary
monitoring design
Gather additional data on
site-specific (retort field)
hydrogeologic framework
Note changes in mine/ re tort
design
Final monitoring design
Implement design for initial
retort field(s)
Evaluate monitoring data and
monitoring design; program
modification likely
Abandonment
Continue data collection/
evaluation
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basis for an evaluation of these sites. A general design process is the sub-
ject of the following discussions.
MONITORING WELL INSTALLATION
Groundwater flow in the study region is controlled by a complex, multi-
layered system of fractures, faults, and solution openings. Detailed, site-
specific hydrogeologic characterization is a necessary precursor to siting
and constructing effective monitoring wells. Recommendations for hydrogeo-
logic testing, leading to design of monitor wells include the following:
1. Relatively small-scale focus in retort fields
2. Close interrelation of hydrogeologic characterization studies
and exploration/resource evaluation operations
3. Iterative reevaluation and scale-up from preliminary data (ex-
ploration core holes) to aquifer testing program to provide
for appropriate placement and consistent completion of testing
and monitor wells
4. Iterative reevaluation of flow net to address variability in
aquifer transmissivity and anisotropic conditions
5. Construction of test and monitor wells in sets to allow con-
sistent (with regard to stratigraphic, hydrologic, and water
quality conditions) well completions
6. Location of monitor wells (a) near and within the retort field
and (b) downgradient along fracture lines and major axis of
an i stotropy
7. Multiple completion of wells within discernible aquifer
subunits
8. Sample collection by pumping.
Hydrogeologic Characterization
The following general plan for hydrogeologic characterization is de-
signed to provide needed information for the location of monitoring wells,
for the design of the wells, and for the operation of the wells (see Sections
5, 9, and 10).
1. Characterization of the groundwater flow regime should focus
on the retort fields directly rather than on the tract region
as a whole.
2. Initial data can be obtained during site exploration/resource
evaluation activities in the following manner:
IX
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a. Exploration core holes should be used as initial hydrogeo-
logic test holes. Core size should be sufficient to allow
preliminary logging and sample collection.
b. Test drilling operations should include observation and
logging by a hydrogeologist; drilling logs provide indi-
rect indication of porous and permeable zones
— Inflow water
-- Loss of drilling fluid
— Changes in drilling rate
— Change in fluid level in bore hole.
c. Test hole reference elevations should be surveyed directly
or sited on topographic maps to facilitate correlation be-
tween test holes.
d. Cores collected during exploration should be evaluated for
hydrogeologic information. Oriented cores are preferred
for identification of fracture and solution features, and
testing of porosity and permeability.
e. Geophysical investigations should be pursued at this phase
of development (see item 4). Depending on the location
and intercorrelation results, exploratory test holes
should be enlarged and used for subsequent monitoring or
testing holes. Otherwise, holes should be filled with
cement.
Data collected during the exploration phases should be com-
pared to other-near-tract data available, and exploration data
should be intercorrelated to develop an initial picture of
local variability and presence of geologic or hydrologic anom-
alies. These data evaluations should then form the basis for
designing the more detailed testing program described below
(items 3 through 7). The data collected in these early phases
should be viewed as preliminary and any sampling installations
as temporary.
3. Other preliminary investigations prior to more detailed
testing:
a. Measure water levels in small-diameter wells completed in
core holes as well as collect water-level data during
drilling efforts.
b. Evaluate potential aquifer boundaries: locate formation
outcrops, faults, and surface water bodies using field
reconnaissance and aerial photography. Faults on Tract
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C-a, for example, have been shown to be barriers to
groundwater flow.
c. From the above, develop preliminary flow net for retort
field area. Use flow net to evaluate possible location of
test and monitor wells.
4. Geophysical logs are recommended as follows:
a- Electric - spontaneous potential (SP) and resistivity:
measure of formation water resistivity, bed thickness
(shales, nonshales)
b. Elastic wave propagation - reflection (amplitude of re-
flected wave):indicates location of vugs and fractures,
orientation of fractures, bed boundaries
c. Radiation - neutron-gamma, gamma-gamma: indicates poros-
ity, density, and water content
d. Miscellaneous
— Temperature logs: indicate formation temperature, flow
direction, relative head levels
— Flow meter (spinner) logs: indicate zones of fluid
entry and discharge
— Caliper logs
-- Fluid conductivity.
5. Aquifer characteristics are best defined by well testing meth-
ods as follows:
a. Testing wells - From the results of the above-described
initial testing, additional wells for detailed hydrogeo-
logic testing should be sited within each proposed retort
field. Aquifer tests conducted during Tract C-a and C-b
baseline programs were at some distance from the proposed
MIS retort fields. Additional data are available.for
Tract C-a as a result of short-term dewatering-reinjection
program testing. These latter type of data are more site-
specific to retort fields than the earlier tests and thus
of more utility for monitoring design purposes. As these
wells may ultimately be used for operational abandonment
monitoring, the goal of this testing is to develop data
allowing consistent (with regard to strati graphic, hydro-
logic, and water quality considerations) well completions.
Three or four wells should be drilled in each retort
field. Two wells should be of sufficient size (minimum
xi
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8-inch casing) for aquifer testing. Other wells need only
be large enough (6 inches) to accommodate smaller pumps
which will be used for water quality sampling. This sec-
ond set of wells will be used initially as aquifer test
observation wells if initial piezometers are not properly
located or are not completed in intervals to be tested.
In addition, they should be used for characterization of
existing water quality and subsequently for abandonment
monitoring to the extent possible.
Aquifer testing - Utilizing information from the prelimi-
nary evaluation program and drillers' logs and geophysical
testing in test and monitor well holes, individual zones
should be isolated with temporary packers for aquifer
testing by pumping. The purpose of such tests is to de-
fine hydro!ogic properties of various permeable zones, to
determine interconnection between adjacent aquifer zones,
and to measure water quality variations between zones.
This testing should finalize data needed for well comple-
tion and sampling design. Test wells should be evaluated
for use in operation/abandonment monitoring. For use in
monitoring, they should be completed and developed as de-
scribed under Well Completion, p xiv. During aquifer
tests, water quality sampling should be undertaken to de-
fine background water quality and to evaluate well sam-
pling procedures for the monitoring program (e.g., length
of pumping time needed to obtain a representative sample).
Test recommendations include the following:
— Use step-discharge approach until acceptable discharge
rate is identified
-- Then use constant-discharge approach
-- Use 2 or more observation wells per test, at different
distances frompumping well to allow evaluation of
time-drawdown and distance-drawdown relationships.
Follow general procedures in Kruseman and DeRidder (1976)
or similar texts. Test should include analysis of both
drawdown and recovery phases. Long-term tests are
recommended
— Until cone of depression stabilizes and does not appear
to vary with continued pumping
— Several weeks pumping may be required to adequately
characterize the system. Questions regarding the tech-
nical adequacy of aquifer tests on Tracts C-a and C-b
are presented in Section 5, including length of pumping
xii
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and recovery periods, and an analysis of test data
(such as correction for nonconstant discharge rate and
choice of method for analysis of recovery priod data).
c* Data analysis - Fully document all data collected, the
rationale for selection of analysis approach; discuss as-
sumptions relative to the system tested. Emphasis should
be placed on estimating transmissivity and evaluating var-
iability (aquifer anisotropy) of transmissivity. These
evaluations should then be utilized to reevaluate prelimi-
nary flow nets to address variability of transmissivity
and anisotropic conditions encountered. Anisotropic flow
nets should be developed as part of existing tract base-
line studies.
6. Evaluate distribution of hydraulic head with depth via:
a. Flow net analysis
b. Water-level changes encountered during drilling
c. Water temperature versus depth (in well bore) data.
7. Develop detailed description of:
a. Flow rates (transmissivity and gradient)
b. Flow direction (horizontal and vertical)
c. Flow boundaries, anisotropy.
Well Location
One of the goals of hydrogeologic characterization efforts is to allow
description of groundwater flow patterns within and near a retort field. The
purpose of this description is to locate monitoring wells so as to sample
flow through and from the retort field area. Monitor wells should be located
as follows:
1. Near retort field (within a few hundred feet) and within the
field
2. Oriented downgradient of the MIS retorts along fracture lines
and major axis of anisotropy as defined by geologic testing
program
3. Accessible for sampling equipment.
Construction of new wells may be required for operation/abandonment mon-
itoring. Wells constructed for hydrogeologic testing may not be appropriately
located for inclusion in the monitoring program.
xm
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Well Completion
Phase I evaluations have indicated that well completion can play a major
role in determining the nature and representativeness of groundwater quality
samples. For example, deep aquifers in the Piceance Basin are composed of
numerous layers of fracture and solution cavities. Most of the wells cur-
rently constructed in the Piceance Basin are open to several of these aquifer
layers. Adjacent layers may differ considerably in water quality and head.
Interconnection of such layers in well bores can result in mixing of waters
of different water quality or in dominance (in water quality samples) of
water from a layer exhibiting greater head than adjacent layers. The former
condition may yield an unacceptable mixed composite of the aquifer layers.
The latter is not a composite and is not truly representative of the open
interval. Under such conditions, baseline water quality may not be adequately
measured; and for operation/abandonment phase monitoring, groundwater flow
through abandoned retorts may not be adequately represented.
For monitoring wells, multiple completions are recommended. As pumping
is the recommended sample collection method, wells with minimum 6-inch-
diameter casing are required to facilitate a suitable submersible pump.
Pumps less than 4 inches in diameter are available. However, the depth of
the wells needed for MIS retort monitoring (e.g., 600 to 700 feet to the
Upper Aquifer in the Piceance Basin) is sufficiently great that larger wells
are needed to avoid problems of wedging of the pump in the well.
Multiple completions of wells which can be pumped for sampling (or mul-
tiple wells completed in different intervals) are obviously more expensive
than single completions. Such multiple completions are not currently being
employed. However, since pumping results in sampling of a large aquifer
cross section, fewer monitor wells will be needed than if bailing or other
nonpumping sampling techniques are employed. These cost tradeoffs will be
considered in more detail in Phase II studies.
Monitoring wells should be completed as follows:
1. Steel casing (structural properties of PVC may preclude its
use for such deep wells)
2. The least costly construction approach is to leave the well
open in the desired interval; such an approach (as opposed to
well screening) is commonly employed for wells drilled in con-
solidated formations
3. The remaining segments of the well bore should be sealed with
cement grout to assure lack of interconnection of sampled in-
tervals (a cement-log should be run to verify the integrity of
this seal)
4. Wells should be pumped thoroughly to remove any traces of
drilling fluid or other materials which may affect water
quality samples.
xiv
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WELL SAMPLING PROCEDURES
Recommendations for well sampling are as follows:
1. Sampling should be by pumping
2. Samples should be collected for analysis only after the well
has been developed by removal of several well volumes of water
3. Conductivity, temperature, and pH should be measured during
development as a guide for identifying an appropriate time for
sample collection
4. Samples should be preserved and handled in the field imme-
diately after collection according to U.S. EPA (1974)
recommendations
5. Sample holding times should be evaluated to determine the need
for on-site analytical facilities
6. Annual to semiannual sampling is probably adequate prior to
retort abandonment and cessation of dewatering; thereafter
monthly sampling is recommended until trends are established
and lower sampling frequencies can be initiated.
Sample Collection
Collection of groundwater samples for chemical analysis should be pre-
ceded by removal of water from the well bore. Sampling of deep aquifers is
currently accomplished by bailing or swabbing techniques on Tracts C-a and
C-b. For the deep wells to be utilized for monitoring MIS retorts, pumping
is recommended. This provides for sampling a greater portion of the aquifer,
thus minimizing the potential for missing or delaying the observation of mo-
bile pollutant constituents.
For monitor well sampling, the following procedure is recommended:
1. Compile preliminary data needed for each well (or separate
completion): well diameter, total depth of well. From these
data the volume of water in the well (well volume) can be cal-
culated for any given well water level. This information plus
"as built" drawings for each well should be available in the
field at the time of sampling.
2. Measure water level and estimate well volume
3. The pump should be set opposite and near the bottom of the
perforated or open interval
4. Develop the well by removal of at least 2 to 3 well volumes
from the well
xv
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5. Measure well water conductivity, temperature, and pH as often
as possible during the well development procedure, but at
least once per well volume discharge
6. Collect and process samples as described in the following sub-
section after a suitable number of well volumes have been re-
moved _and water quality of the well discharge has stabilized
(as measured by pH, temperature, and conductivity).
Sample Preservation and Handling
Sample preservation and handling requirements are dictated by the nature
of the constituents to be analyzed. For the recommended constituents, the
holding times listed below are recommended by U.S. EPA (1974). Bottle re-
quirements (plastic versus glass) are also provided in this reference. Fil-
tering of samples immediately after collection is recommended with addition
of chemical preservatives in the field at the time of collection or addition
of preservatives to sample bottles prior to initiation of field activities.
General water quality constituents
Total dissolved solids
(filterable residue)
Conductance
pH
Alkalinity
Major inorganics.
Calcium, magnesium, potassium,
and sodium
Bicarbonate
Carbonate
Chloride
Nitrate
Sulfate
Fluoride
Ammon i a
Phosphate
*Assumed same as alkalinity.
Preservative
Cool, 4°C
Cool, 4°C
Determine on site
Cool, 4°C
Nitric acid to pH < 2
Cool, 4°C*
Cool, 4°C*
None required
Cool, 4°C
Cool, 4°C
Cool, 4°C
Cool, 4°C, sulfuric
acid to pH < 2
Cool, 4°C
Maximum
holding
time
7 days
24 hours
6 hours
24 hours
6 months
24 hours*
24 hours*
7 days
24 hours
24 hours
7 days
24 hours
24 hours
(continued)
xvi
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Organics
Dissolved organic carb<
Kjeldahl nitrogen
Trace metals
Arsenic
Selenium
Vanadium
Molybdenum
Mercury
Preservative
Cool, 4°C, sulfuric
acid to pH < 2
Cool, 4°C, sulfuric
acid to pH < 2
Maximum
holding
time
24 hours
24 hours
Nitric acid to pH < 2
Nitric acid to pH < 2
Nitric acid to pH < 2
Nitric acid to pH < 2
Nitric acid to pH < 2
6 months
6 months
6 months
6 months
38 days
(glass
container)
The short holding times listed here will be difficult, if not impossible,
to accomplish in the remoteness of the oil shale region unless on-site labor-
atory facilities are developed. Such an approach is recommended for the
following:
• Conductance
• pH
• Alkalinity
• Carbonate
• Bicarbonate
• Chloride
• Ammonia (electrode method)
• Fluoride (electrode method).
Since it may not be feasible to meet the listed holding time requirements
for many of the constituents listed (e.g., TDS, nitrate, sulfate, phosphate,
DOC, and Kjeldahl nitrogen), it is recommended that .testing be initiated so
that more suitable holding times for the waters in question can be defined
and the nature and significance of errors evaluated.
Sampling Frequency
Proper selection of well sampling frequency is a function of potential
pollutant mobility, and when hard data are not available, the selection is
xvn
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often made by trial and error. Shallow groundwater systems commonly display
response to seasonal or otherwise cyclic events of recharge and infiltration
of dissolved constituents from the surface. Regional pumping patterns can
also affect the variability of water quality in both deep and shallow wells.
Such variability would necessitate relatively greater sampling frequencies.
The aquifers to be monitored for the impacts of abandoned MIS retorts
are relatively deep and not subject to great variability from recharge
events. Such influence of cyclic events is usually attenuated during slow
passage through the aquifer. Hence, a somewhat low sampling frequency is
appropriate.
Another consideration is the sequence of events leading to abandonment,
namely, mine-retort operation, termination of retorting, termination of de-
watering, and recovery of aquifer water levels in the mine-retort area. Dur-
ing the operational phase, particularly when dewatering is appreciable, no
releases would be anticipated from the MIS retorts. Thus, low-frequency sam-
pling (e.g., annual) would be adequate. If dewatering is via wells (rather
than strictly from the mine itself), the dewatering wells (sampled individ-
ually) may be an acceptable location for sampling. Any groundwater flow
within the retort field during this dewatering phase would be dominated by
and directed toward the dewatering wells. Thus, any appreciable groundwater
movement in the retort interval would be effectively sampled by these wells.
During the time from cessation of dewatering through stabilization of
water levels, the groundwater system would be in a state of flux and rapid
changes in water quality may occur. During this period, more frequent sam-
pling is recommended. Initially, monthly sampling is appropriate to estab-
lish patterns of temporal variability. This frequency can then probably be
diminished to semiannual and then perhaps to annual as time trends are estab-
lished. Several years may pass before these low frequencies are appropriate.
SAMPLE ANALYSIS
Recommendations for sample analysis are as follows:
1. Routine monitoring of constituents listed in the preceding
discussion of sample preservation and handling
2. More extensive sample collection and analysis (such as unique
indicators discussed in Section 10) should the routine sam-
pling program indicate an impact of MIS retorts on groundwater
quality
3. Use of standard analytical methods.
The constituents listed in the preceding discussion of sample preserva-
tion were selected for routine monitoring because high levels are expected
should materials leach from MIS retorts. In addition, constituents include
those which allow data checks (TDS-conductivity, cation-anion balance, etc.)
to be performed as a quality control measure. Should this routine monitoring
program indicate an impact of MIS retorts on groundwater quality, more
xviii
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extensive analysis of samples is recommended. This analysis should include
the sets of possible unique indicators presented in Section 10 of this report.
This recommended list of constituents includes fewer constituents than
the analysis sets of presently implemented monitoring programs, such as out-
lined in Section 9 of this report. This shortened list should allow detec-
tion of groundwater quality impacts due to MIS retorts while economizing on
analytical needs.
Other sets of constituents, such as various organic fractionations and
stable isotope ratios, need to be evaluated further, particularly the inter-
pretation of such data with regard to indicating the impact of oil shale by-
products. Standard analytical methods, such as presented by U.S. EPA (1974)
or in Standard Methods (American Public Health Association, 1976) should be
employed.
PHASE II STUDIES
A preliminary monitoring design/implementation framework has been.devel-
oped and is outlined above. Another product of the analysis leading to this
preliminary design is the identification of areas of uncertainty with regard
to implementation of groundwater quality monitoring programs for MIS retorts.
Phase II study plans have been developed to supplement the information base
presented in this report and to provide additional cost-effectiveness bases
for developing a monitoring design guideline. To the extent possible, these
data collection efforts will be coordinated with-other research efforts.
Three basic tasks have been identified for the Phase II studies, these
tasks are considered in detail in Section 11 of this,report:
1. Task 1. Sampling Evaluation
a. Well sampling approaches
b. Well construction
c. Sample handling and preservation
2. Task 2. Hydrogeologic Characterization
a. Geophysical methods
b. Other testing procedures
c. Evaluation of mine development phase data
3. Task 3. Characterization of In-Situ Retort Source
a. Chemical 'analysis
b. Leaching and mobility.
xix
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Task 1 includes assessment of various sampling factors which influence
water quality data. Various sample collection methods have been used during
oil shale tract baseline surveys. Tests of bailing versus pumping and of the
effect of various pumping procedures will be conducted, as these factors in-
fluence water quality samples. Because of the-relative remoteness of the
study region, meeting current EPA specifications of sample holding time is
very difficult. Tests to determine the influence of various holding times
will be conducted.
Well construction has been shown to greatly influence water quality in
the oil shale region. During Phase II, the data base on methods used in
Piceance Basin will be extended beyond tract-related operations. Well size,
annular sealing, casing material, perforation, and well development methods
will be considered. Probable influences on water quality samples will be
evaluated and cost data compiled for alternative approaches. Water quality
data collected before and after the current Tract C-b recompletion program
will be compiled and compared.
Task 2 studies will supplement Phase I evaluations of methods for char-
acterizing MIS retort sites. Such characterization is an essential element
for siting monitor wells and for the design of the wells (e.g., perforated
interval) to obtain consistent and representative samples. Geophysical and
other testing methods will be evaluated and ranked relative to cost, poten-
tial effectiveness, and availability of testing equipment.in the oil shale
region. Data developed during Tracts C-a and C-b mine development (e.g.,
fracture mapping) will be compiled and used to assess the geophysical and
hydro!ogical testing procedures utilized on the tracts.
Task 3 is a continuation of preliminary assessments related to the selec
tion of constituents for monitoring. These tests and evaluations of leaching
characteristics and mobility/attenuation mechanisms will be used to support
final recommendations of constituents to be monitored based on likelihood of
meeting previously outlined monitoring goals and on cost considerations.
Phase II studies will develop data for final monitoring recommendations.
The basic issues of how, where, and what to sample will be considered in Task
1, 2, and 3 as outlined above. The final recommendations will be presented
in a format allowing planning and implementation of groundwater quality moni-
toring programs by the various industrial and regulatory groups involved in.
monitoring.
xx
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CONTENTS
Page
Foreword iii
Preface v
Summary and Design Recommendations vi
List of Figures xxiii
List of Tables xviii
List of Abbreviations and Symbols xxxi.
English/Metric System xxxvi
Acknowledgments xxxvii
Section
Introduction to Monitoring Area 1
Introduction 1
Federal Prototype Lease Development 2
Oil Shale Monitoring Design Program 4
Potential Sources of Pollution and Methods of Disposal 7
Overview of Modified In-Situ Development 7
Development Summary—Tract C-a 11
Development Summary—Tract C-b 27
Potential Pollutants 35
Retort Water 35
In-Situ Spent Shale 40
Groundwater Use 50
Hydrogeologic Framework 51
'Physiography 51
Regional Stratigraphy 53
Structure 56
General Basin Hydrogeology 56
Hydrogeology of Tract C-a 60
Hydrogeology of Tract C-b 78
Surface Water Hydrology 92
Existing Water Quality 97
General Basin Water Quality 97
Tract C-a Groundwater Quality 100
Tract C-b Groundwater Quality 111
xx i
-------
Section
7 Potential Pollutant Mobility
Introduction
Groundwater Flow
Mobility and Attenuation Factors
Models of Potential Pollutant Mobility
8 Preliminary Priority Ranking of Potential Pollution
Sources 142
9 Evaluation of Existing Monitoring 150
Tract C-a Monitoring 150
Tract C-b Monitoring 158
Other Monitoring Programs 165
General Monitoring Approach 165
Sampling Methods 167
Other Sampling Considerations 172
Monitoring Evaluation 180
10 Monitoring Approaches 186
Potential Pollutants 186
Hydrogeologic Characterization 187
Sampling and Analysis 195
11 Monitoring Design Program 239
Introduction 239
Monitoring Design Strategy 240
Phase II Studies 246
References 257
Appendix
A Conceptual Models of Pollutant Mobility 262
Conceptual Model 1 262
Conceptual Model 2 264
Conceptual Model 3 269
References 279
xxn
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FIGURES
Number Page
1-1 Location of Tracts C-a and C-b study area in Piceance
Creek Basin. 6
1-2 Generalized development of modified in-situ retort. 8
2-2 Schematic layout of mine access and modified in-situ retorts. 13
2-3 General location map of Tract C-a facilities. 15
2-4 Site plan for Tract C-a development. 16
2-5 Flow diagram of commercial phase processing facility. 22
2-6 Water flow schematic for Tract C-a development. 23
2-7 Plot plan for Tract C-b development. 28
2-8 Flow diagram for Tract C-b commercial operations. 31
5-1 Major structural features in study area. 52
5-2 Geologic section through the Piceance Basin along
north-south line between Tracts C-a and C-b. 54
5-3 Distribution of transmissivity in the Lower Aquifer. 58
5-4 Distribution of transmissivity in the Upper Aquifer. 59
5-5 Potentiometric map based on water levels in wells open to
to the Upper and Lower Aquifers, April 1974. 61
5-6 East-west geologic cross section through Tract C-a. 63
5-7 Tract C-a middle A-groove structure map. 64
5-8 Monthly mean flows at seven gaging stations, water years
1975 and 1976, 65
5-9 Springs and seeps in vicinity of Tract C-a. 66
xxm
-------
Number Page
5-10 Tract C-a monitoring holes. 68
5-11 Alluvial hole water level versus stream-flow. 70
5-12 Cross section, Upper and Lower bedrock aquifer under
Tract C-a. 71
5-13 Upper and Lower bedrock aquifers under Tract C-a. 72
5-14 Upper Aquifer piezometric levels, Tract C-a, November 1975. 74
5-15 Upper Aquifer test drawdown, 6-S 12 at approximately
13,000 minutes after test start, Tract C-a. 74
5-16 Upper Aquifer test cone of depression, Tract C-a. 75
5-17 Potentiometric surface for Upper Aquifer reconstructed from
Figure 5-14 to show influence of faults on Tract C-a. 75
5-18 Anisotropic flow net for Upper Aquifer on Tract C-a. 76
5-19 Lower Aquifer piezometric levels, Tract C-a, November 20,
1975. 77
5-20 Lower Aquifer test cone of depression. 79
5-21 North-south geologic cross section of Tract C-b. 81
5-22 Monthly averages by season for streamflow at Piceance Creek
above Ryan Gulch, US6S 09306200, and for precipitation at
Meeker, 1965-1975. 82
5-23 Double-mass curve for White River near Meeker and below
Meeker and Piceance Creek below Ryan Gulch. 83
5-24 Springs and seeps in the Tract C-b area. 84
5-25 Hydrographs of springs near Tract C-a, 1974-1976. 85
5-26 Potentiometric surface of Upper Aquifer, Tract C-b. 87
5-27 Anisotropic flow net of Upper Aquifer on Tract C-b initial
development plot plan. 91
5-28 Lower Aquifer potentiometric map, Tract C-b. 93
5-29 Location of streamflow gaging stations. 94
5-30 Maximum, minimum, and mean monthly runoff from Piceance
Creek at Rio Blanco, below Ryan Gulch, and at White River. 95
xxiv
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Number Page
6-1 Concentration of dissolved solids in the Lower Aquifer,
May-September 1973. 98
6-2 Concentration of dissolved solids in the Upper Aquifer,
May-September 1973. 99
6-3 Time trend plots for concentrations of chemical constituents
in Tract C-a alluvium. 104
6-4 Trilinear diagram of water quality data for Upper and Lower
Aquifers, Tract C-a. 105
6-5 Trilinear diagram comparing inorganic composition of ground-
waters to pH level, Tract C-a. 106
6-6 Trilinear diagram comparing inorganic composition of ground-
waters to total dissolved solids concentration, Tract C-a. 107
6-7 Trilinear diagram comparing inorganic composition of ground-
waters to water temperature, Tract C-a. 108
6-8 Intervals of perforation of wells on Tract C-a. 110
6-9 Intervals of perforation of wells on Tract C-b. 112
6-10 Trilinear diagram presenting groundwater quality data for
Tract C-b. 113
6-11 Trilinear diagram comparing inorganic composition of ground-
waters to pH level, Tract C-b. 115
6-12 Trilinear diagram comparing inorganic composition of ground-
waters to total dissolved solids concentration, Tract C-b. 116
6-13 Trilinear diagram comparing inorganic composition of ground-
waters to water temperature, Tract C-b. 117
6-14 Trilinear diagram comparing inorganic composition of ground-
waters to stratigraphic section, Tract C-b. 118
6-15 North-south and east-west stratigraphic sections showing
specific conductance profiles in selected wells on Tract C-b. 121
7-1 Approximate location of Tract C-a retort zone in geologic
cross section. 133
7-2 Tract C-a in-situ retort zone in relation to geologic cross
section. 133
xxv
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Number Page
7-3 Approximate location of Tract C-b retort zone in geologic
cross section. 134
7-4 Anisotropic flow net of Upper Aquifer superimposed on
Tract C-a plot plan. 136
7-5 Anisotropic flow net of Upper Aquifer superimposed on
Tract C-b initial development plot plan. 137
9-1 Locations of modular development phase surface water and
groundwater monitoring stations, Tract C-a. 156
9-2 Surface water monitoring stations, Tract C-b. 163
9-3 Alluvial and deep aquifer monitoring wells, Tract C-b. 164
9-4 Anisotropic flow net of Upper Aquifer superimposed on
Tract C-b plot plan and existing deep aquifer wells. 166
9-5 Anisotropic flow net of Upper Aquifer superimposed on
Tract C-b initial development plot plan. 167
9-6 Generalized aquifer-aquitard system on Tract C-b. 176
9-7 Current well completions, subsurface hydrology monitoring
program, Tract C-b. 177
9-8 Planned well completion, subsurface hydrology monitoring
program, Tract C-b. 178
9-9 Intervals of perforation of wells on Tract C-a. 181
10-1 Sample of groundwater flow net. 200
10-2 Idealized two-dimensional pattern showing the relation
between true direction of groundwater flow and the
direction inferred by drawing orthogonal lines of regional
water-level contours. 201
10-3 Fractured-rock aquifer system yielding water of varying
quality depending on location and perforation of wells. 202
10-4 Schematic of size of aquifer cross section sampled by
bailing, by swabbing, and by pumping of monitor well. 205
10-5 Water quality data display using vectors. 236
10-6 Trilinear diagram for displaying water quality data. 237
11-1 Preliminary outline—monitoring guideline document. 240
xxvi
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Number Page
A-l Geohydrologic cross section of the Piceance Basin showing
relationship of in-situ retorts to adjacent aquifers. 263
A-2 Schematic describing possible groundwater transport of
leached contaminants. 263
A-3 Hypothetical oil shale tract showing retort fields and
sequence of development. 271
A-4 Retort-aquifer configurations and groundwater flow paths. 271
A-5 Groundwater flow into an abandoned retort. 273
A-6 Groundwater flow lines through a saturated equivalent
circular retort. 274
A-7 Groundwater pollution concentration as a function of time
from an oil shale tract. 277
A-8 Relative pollution concentration as a function of distance
from an oil shale tract and of rate of dispersion. 278
xxvn
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TABLES
Number Page
1-1 Oil Shale Reserves in the Green River Formation 1
1-2 TEMPO Monitoring Methodology 4
2-1 Summary of Potential Sources of Groundwater Quality Impact,
Tracts C-a and C-b 9
2-2 Estimated Acreages of Land Scheduled to be Disturbed and
Revegetated on Tract C-a 26
2-3 Estimated Surface Disturbance by Year and Overall 34
3-1 Chemical Characterization of Simulated and Observed
In-Situ Oil Shale Process Water 36
3-2 Characterization of Retort Water from (True In-Situ)
Retort No. 9, Rock Springs, Wyoming, and from Modified
In-Situ Retort 38
3-3 Characteristics of In-Situ Retort Water Reported in
Available Literature 41
3-4 Summary of Literature Data on Leachate (Using Distilled
Water) from Simulated In-Situ Retorted Shale and from
Surface Retorted Shale 46
3-5 Estimated Quantities of Material Leached from Spent Shale 48
3-6 Water Quality Analysis of Groundwater Near True In-Situ
Oil Shale Experiment 49
5-1 Precipitation Summary, Water Years 1975 and 1976 64
5-2 Annual Runoff 66
5-3 Suggested Source of Spring Water 67
5-4 Summary of Alluvial Monitoring Holes Physical Data 69
5-5 SG-17 Drill Stem Tests 89
xxviii
-------
Number Page
5-6 SG-17 Multipacker Tests 90
5-7 Results of Aquifer Tests on Oil Shale Lease Tract C-b 90
6-1 Summary of Water Quality from Alluvial Aquifers,
Tract C-a 102
6-2 Summary of Water Quality of Groundwaters of Tract C-b 122
6-3 Summary of Trace Element Levels in Groundwater of Tract C-b 124
6-4 Comparison of Tract C-b Upper and Lower Aquifer Water
Quality with Colorado Water Quality Standards 126
6-5 Results of Organic Fractionation Analysis of Waters near
Tract C-b 127
8-1 Summary Table of Data and Assessments for Potential Pollution
Associated with In-Situ Oil Shale Development 143
8-2 Preliminary Priority Ranking of Potential Pollution Sources 149
9-1 Summary—Proposed Hydrology Monitoring Program, Tract C-a 151
9-2 Water Quality Sampling, Tract C-a 152
9-3 Summary of MDP Aquifer Test Monitoring Program, Tract C-a 159
9-4 Water Quality Sampling Program—Tract C-b 160
9-5 Conductivity Level of Swabbed Samples, Tract C-b,
Fall 1976 174
9-6 Fluoride and Boron from Lower Aquifer Test 174
9-7 Upper Aquifer Monitoring Network 179
9-8 Lower Aquifer Monitoring Network 179
10-1 Geophysical Well Logging Methods and Their Applications 191
10-2 Selected Production-Injection Logs and Their Function 193
10-3 Range of Conductivity Observed and Final Conductivity
Level of Swabbed Samples, Tract C-b, Fall 1976 204
10-4 Fluoride and Boron from Lower Aquifer Test 205
10-5 Flow Rates of the Upper Aquifer, Piceance Creek Basin,
Estimated by Three Studies 207
xx ix
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Number Page
10-6 Representative Concentrations in Groundwaters Adapted
for this Study 209
10-7 Species Enriched in the Lower Aquifer 211
10-8 Enrichment Factors Estimated for Spent MIS Oil Shale
Leachate 212
10-9 Enrichment Factors for Retort Waters 214
10-10 Relative Likelihood of Detection of Mobility from Various
Sources to Upper and Lower Aquifers and Springs Based on
Estimated Enrichment Factors 217
10-11 EPA Recommended Holding Times Compared to Experimentally
Established Holding Times 225
10-12 Comparison of Analytical Techniques for Trace Element
Determinations 228
A-l Estimated Composition of Leachate Within a Spent In-Si.tu
Retort Located in the Piceance Basin 266
A-2 Estimated Duration of Groundwater Pollution Produced by
an Oil Shale Tract 275
xxx
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS AND SYMBOLS
AA atomic absorption spectroscopy
AOSS Area Oil Shale Supervisor
API American Petroleum Institute
bbl barrel(s)
BPSD barrels per stream day
°C degrees Centigrade
cfs cubic feet per second
DDP Detailed Development Plan
DOE Department of Energy
EF enrichment factor
EPA U.S. Environmental Protection
Agency
°F degrees Fahrenheit
FGD flue-gas desulfurization
ft foot, feet
ft^ square foot, square feet
g gram(s)
GC gas chromatography
GC/MS gas chromatography/mass
spectroscopy
gm/cc grams per cubic centimeter
gpm gallons per minute
HPLC high-pressure liquid
chromatography
HPTLC high-pressure thin-layer
chromatography
ICP inductively coupled plasma
emission spectroscopy
INAA instrumental neutron activation
analysis
Ib/hr pounds per hour
LERC Laramie Energy Research Center
LTPD long tons per day
MBAS methylene blue active
substances
md millidarcy
MDP modular development phase
meq/1 milliequivalents per liter
mg/1 milligrams per liter
MIS modified in situ
mi/yr miles per year
ml milliliter(s)
MMSCFD million standard cubic per day
NPDES National Pollution Discharge
Elimination Center
PAH polynuclear aromatic hydrocarbons
xxx i
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ABBREVIATIONS (continued)
pCi/1 picocuries per liter
PNA polynuclear aromatics
POM polycyclic organic matter
PVC polyvinyl chloride
RBOSP Rio B'lanco Oil Shale Project
SMSS spark source mass spectrometry ug/1
(spectroscopy)
umho
SP spontaneous potential
umho/cm micromhos per centimeter
T transmissivity
TLC thin-layer chromatography
TOSCO The Oil Shale Company
TPD tons per day
TPY tons per year
USGS U.S. Geological Survey
micrograms per liter
micromho(s)
CHEMICALS, IONS, CONSTITUENTS
Al aluminum
Ag silver
As arsenic
B boron
Ba barium
Be beryllium
Bi bismuth
BOD biological oxygen demand
Br bromi ne
C carbon
C4 four-carbon hydrocarbon
2+
Ca, Ca calcium
CaC03 calcium carbonate
CaF2 fluorite
CaO
Cd
Ce
CIT
Co
C02
co3,co3
COD
Cr
Cs
Cu
DOC
Dy
Er
lime
cadmi urn
ceri urn
cyanide
cobalt
carbon dioxide
carbonate
chemical oxygen demand
chromi urn
cesium
copper
dissolved organic carbon
dysprosium
erbium
xxxn
-------
CHEMICALS,
Eu
F
Fe
Fe(SCN)x
Ga
Gd
Ge
H20
H2S
HC
HC03, HCO"
Hf
Hg
Ho
I
K
La
Li
Lu
Mg
Mn
Mo
IONS, CONSTITUENTS (continued)
europium N
fluorine Na
iron
ferrous iron NaHC03
ferric thiocyanite NaCI
gallium Nb
gadolinium NH3
germanium NH3-N
water NH.-N
hydrogen sulfide Ni
hydrocarbon NOX
bicarbonate N02-N
hafnium N03
mercury N03-N
mercuric chloride 0
hoi mi urn OH, OH-
iodine P
potassium Pb
potassium dichronate Po
lanthanum P04
lithium Pr
lutetium Rb
magnesium R-C02
manganese
R-NH2
molybdenum
nitrogen
sodium
dawsonite
nahcolite
halite
niobium
ammonia
ammonia nitrogen
ammonium nitrogen
nickel
nitrous oxides
nitrite nitrogen
nitrate
nitrate nitrogen
oxygen
hydroxide
phosphorus
lead
polonium
phosphate
praseodymium
rubidium
hydrocarbon with C02
group attached
hydrocarbon with NH2
group attached
xxxm
-------
CHEMICALS, IONS, CONSTITUENTS (continued)
s
s-
S2°3
s.o"
4 6
Sb
Sc
SCN-
Se
Si
Si02
so4, :
Sr
Ta
Tb
sulfur
sulfide
thiosulfate
tetrathionate
ant i mony
scandium
thiocyanate
selenium
silica
silica dioxide
50^ sulfate
strontium
t ant al urn
terbium
TDS
Te.
Ti
T1
Tm
TOC
U
V
w
Y
Yb
Zn
Zr
total dissolved solids
tellurium
titanium
thallium
thulium
total organic carbon
uranium
vanadium
tungsten
yttri urn
ytterbium
zinc
zirconium
FORMULAE ABBREVIATIONS
'max
maximum transmissivity
major axis of drawdown
ellipse
minor axis of drawdown
ellipse
effective transmissivity
minimum transmissivity
major isotope
minor isotope
6 variation in isotope abundance
M-J mass of ith constituent
m mass of spent shale
^C"i average concentration of ith
constituent
K aquifer permeability
i groundwater level gradient
C/CQ concentration relative to
standard concentration, CQ
xxxiv
-------
FORMULAE ABBREVIATIONS (continued)
(Cg)-j concentration of ith
constituent in groundwater
V pore volume
a aquifer porosity
L flow distance
a dispersion coefficient
h£-h]_ head difference at
locations 1 and 2
r2~rl difference in radius measure-
ments at locations 1 and 2
W flow width
Q flow rate (ft3/day)
xxxv
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ENGLISH/METRIC SYSTEM
0 Fahrenheit
1 gallon
1 barrel
1 cubic yard
1 cubic foot
1 acre-foot
1 pound
1 acre
1 quart
1 foot
1 square mile
1 ton (short)
("Centigrade x 9/5) - 32
3846.2 cubic centimeters
3.86 liters
0.16 cubic meter
0.77 cubic meter
0.028 cubic meter
1250 cubic meters
0.0005 tonne (metric ton)
487.8 grams
0.0004 hectare
0.9463 liter
0.305 meter
2.59 square kilometers
0.909 tonne (metric ton)
xxxvi
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ACKNOWLEDGMENTS
Dr. Guenton C. Slawson, Jr., and Dr. Lome G. Everett of General
Electric—TEMPO were responsible for management and technical guidance of
this project under which this report was prepared. Mr. Fred M. Phillips of
TEMPO was a principal author of the report. Mr. Edward W. Hoylman was a
supporting author.
Supporting consultants assisting in development of this report were:
Dr. Kenneth D. Schmidt
Dr. David K. Todd
Dr. Donald L. Warner
Dr. Lome G. Wilson
Mr. Coyd Yost.
Technical consultation and review for this study were also provided by
Dr. David B. McWhorter, Colorado State University, and by Mr. Glen A. Miller,
U.S. Geological Survey, Conservation Division, Area Oil Shale Supervisor's
Office.
In addition, TEMPO wishes to acknowledge the support and cooperative
interaction of representatives of Tract C-a and C-b developers:
Rio Blanco Oil Shale Company
-- Mr. Sam H. Miller
— Ms. Rosalie Gash
— Ms. Maria Moody
C-b Shale O.il Venture
— Mr. R.E. Thomason
— Ms. C.A. Neiuwenhuis (now with Union Oil Co.)
-- Mr. C.B. Bray.
xxxvn
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SECTION 1
INTRODUCTION TO MONITORING AREA
INTRODUCTION
Synthetic petroleum products recovered from western oil shales are
expected to play an important part in supplying future energy needs of the
United States. Various estimates of the magnitude of western oil shale
reserves have been made. The U.S. Geological Survey estimates that an
equivalent of about 4000 billion barrels* of oil are contained in the oil
shales of the Green River Formation of Utah, Colorado, and Wyoming (Table
1-1). These oil shale resources account for 80 percent of the known world
resources but, of course, are not completely recoverable. Recoverable re-
sources are a function of mining and retorting technology and economics, but
may amount to about 1800 billion barrels of oil (Hendricks and Ward, 1976).
As the estimated remaining world ultimate oil resources are about 2000 bil-
lion barrels (Tiratsou, 1976), of which less than 150 billion barrels are in
the United States, western oil shale is clearly a significant energy resource.
TABLE 1-1. OIL SHALE RESERVES IN THE GREEN RIVER FORMATION*
Shale
grade
(gallons
oil /ton)
25-65
10-25
5-10
Uinta
Basin,
Utah
(billions
of barrels)
90
230
1,500
1,820
Piceance
Creek
Basin,
Colorado
(billions
of barrels)
500
800
200
1,500
Green
River
Basin,
Wyoming
(billions
of barrels)
30
400
300
730
Total
(billions
of barrels)
620
1,430
2,000
4,050
From.Hendrickson, 1975.
* See pp xxxvi for conversion to metric units. English units were used in
this report because of their current usage and familiarity in industry and
the hydrology-related sciences.
1
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FEDERAL PROTOTYPE LEASE DEVELOPMENT
The current Federal Prototype Oil Shale Leasing Program, administered by
the U.S. Department of Interior, was initiated in 1969. Program planning and
environmental evaluation efforts by various government interagency and indus-
try groups culminated in preparation of a draft environmental impact statement
in 1971. Informational core hole drilling by firms interested in obtaining
oil shale leases was conducted in the 1971 through 1973 period. This led to
nomination of twenty potential lease tracts in Colorado, Utah, and Wyoming.
The Department of Interior selected six tracts for the prototype leasing pro-
gram. The environmental impact statement was finalized in 1973. Later in
1973, the first lease sale was initiated. In January 1974, successful bid-
ders for the two Colorado lease tracts (C-a and C-b) and for two Utah tracts
(U-a and U-b) were announced. No bids were received on the proposed Wyoming
lease tracts.
Environmental baseline and operation design studies were conducted over
the two years following the lease initiation. In 1976, Detailed Development
Plans (DDP) were submitted for both Tracts C-a and C-b. The initial DDP for
Tract C-a called for open pit mining, surface retorting, and off-tract loca-
tions for processing facilities, overburden and processed shale disposal. A
number of serious problems, particularly approval for off-tract disposal of
wastes could not be resolved and a lease suspension was requested. This sus-
pension was granted in September 1976. During the suspension, a revised DDP
for Tract C-a was prepared calling for modified in-situ (MIS) development
plus surface retorting of the oil shale mined from development of the MIS
retorts. This revised DDP was submitted in May 1977 and was subsequently
approved by the Area Oil Shale Supervisor (AOSS). As described in Section 2,
a modular development program was proposed and has been initiated on Tract
C-a.
Initial development plans on Tract C-b (by Ashland Oil, Inc., and Shell
Oil Company) were submitted in February 1976. This plan called for a deep
mining and surface retorting (and disposal) operation. Development was sus-
pended later in 1976. In November of that year, Shell withdrew from the C-b
Oil Shale Project and Ashland formed a new venture with Occidental Oil Shale,
Inc. A revised DDP proposing MIS operations was submitted in February 1977.
Site development was initiated in the fall of 1977.
The economic feasibility for retorting oil shales in situ looks promis-
ing, based on recent tests conducted by Occidental Oil Shale, Inc. Serious
environmental impacts may result from in-situ retorting and the on-site up-
grading and processing of the recovered oil. These impacts should be antici-
pated and avoided to the extent possible—any decision to accept environmental
damage, for example, a reduction in groundwater quality, should be a conscious
one based on the best information and analysis available.
Development of this resource so far has taken place only on a prototype
scale because accessible supplies of oil and gas have been available at a
lower development cost. The Nation's future energy needs are so large, how-
ever, that it is necessary to examine the possibility of supplementing our
-------
conventional domestic oil and gas deposits with synthetic fuels derived from
oil shale.
Monitoring of groundwater quality impacts associated with in-situ oil
shale development will be difficult. Retort waters produced by small-scale
in-situ operations have resulted in the identification of a wide spectrum of
potential pollutants. Research to date indicates that many of these pollu-
tants have only recently been classified, while others are still under in-
vestigation. It is not clear if the quality of the retort waters from
small-scale in-situ retorting will be similar to those waters produced by
large-scale commercial in-situ retorts.
Shale deposits in the Piceance Basin that can potentially be exploited
by in-situ technologies underlie an area of considerable topographic varia-
tion that is largely undeveloped. A wide range in both hydro!ogic and geo-
logic conditions occurs throughout the area containing the deposits. Several
in-situ technologies are available, each of which could have characteristic
impacts. There has not been sufficient experience with the various retorting
methods to determine which is the most suitable in terms of minimizing envi-
ronmental harm in the Piceance Basin. It may appear at first glance that
in-situ retorting has les*s potential for impact to the environment than sur-
face retorting; however, the long-term impact to the subsurface environment
may prove this assumption to be wrong.
Groundwater presently plays a key role in satisfying U.S. water needs
for municipal, agricultural, and industrial uses. In addition, groundwater
discharges to streams and rivers comprise a significant percentage of surface
water supplies. During low flow periods, almost all surface flow results
from groundwater discharges. This interaction between surface water and
groundwater is an important consideration in the evaluation of groundwater
pollution; subsurface contamination may ultimately affect both surface water
and groundwater users.
The Federal Water Pollution Control Act Amendments of 1972 (P.L. 92-500)
and the Safe Drinking Water Act of 1974 (P.L. 92-523) provide for protection
of groundwater quality. These mandates call for programs to prevent, reduce,
and eliminate pollution of both navigable waters and groundwater and for par-
ticular protection of drinking water resources. Similar goals are embodied
in the Toxic Substances Control Act of 1976 and the Resource Conservation and
Recovery Act of 1976. The national responsibility for these various activi-
ties is given to the U.S. Environmental Protection Agency (EPA). Various
State agencies also have similar responsibilities via State enabling
legislation.
The mandates of P.L. 92-500 necessitate implementation of a system for
detecting and delineating groundwater pollution before points of use are
affected and preferably before pollutants enter the subsurface. Monitoring
approaches for these requirements are in marked contrast with more tradi-
tional programs aimed at sampling water quality and quantity at the point of
supply for a specific use. The design problem described in this report has
been addressed using a systematic approach for predictive groundwater quality
monitoring developed by General Electric—TEMPO of Santa Barbara, California
-------
(Table 1-2). This stepwise methodology includes identification of pollution
sources, their associated pollutants, and the potential for mobility of these
pollutants in the specific hydrogeologic framework of the study area.
TABLE 1-2. TEMPO MONITORING METHODOLOGY
Step Description
1 Select Area for Monitoring
2 Identify Pollution Sources, Causes, and Methods of Disposal
3 Identify Potential Pollutants
4 Define Groundwater Usage
5 Define Hydrogeologic Situation
6 Describe Existing Groundwater Quality
7 Evaluate Infiltration Potential of Wastes at the Land Surface
8 Evaluate Mobility of Pollutants from the Land Surface
9 Evaluate Attenuation of Pollutants in the Saturated Zone
10 Prioritize Sources and Causes
11 Evaluate Existing Monitoring Programs
12 Identify Alternative Monitoring Approaches
13 Select and Implement the Monitoring Program
14 Review and Interpret Monitoring Results
15 Summarize and Transmit Monitoring Information
OIL SHALE MONITORING DESIGN PROGRAM
This report presents the results of a monitoring design study of in-situ
oil shale development. The approach used is the general methodology outlined
in Table 1-2. In particular, this report deals with an initial pass through
methodology steps 1 through 13, although step 13 is not fully implemented.
The methodology, in general, and its application to monitoring design prob-
lems are described in several other reports (Todd et al., 1976; Slawson,
1979; and Everett, 1979) and will not be presented here in detail.
The potential for development of oil shale resources in the Western
United States is briefly summarized in the preceding paragraphs. Because of
-------
the magnitude of these resources and the likely expansion of this new indus-
try to meet ever-accelerating energy needs of the United States, proposed oil
shale developments were reviewed by the EPA to identify candidate study areas.
After a review of the proposed developments, the Utah Federal Prototype
Lease Tracts were considered generally representative of deep mining-surface
retorting oil shale developments. An assessment of this development is the
subject of other reports completed for this study (Slawson, 1979, 1980).
Many of the results of the Utah study are transferable to the design of
groundwater quality monitoring programs for similar oil shale enterprises
both in Utah and in other parts of the Western United States. For this
reason, the study presented in this report focuses on the components of in-
situ operations which have no counterpart in deep mine-surface retorting
operations.
The assessments outlined in the following sections of this report focus
on modified in-situ development as proposed for Federal Prototype Lease
Tracts C-a and C-b in Colorado (Figure 1-1). The results of this evaluation
should, in general,.be applicable to other sites in the oil shale region of
the Western United States. However, site-specific features of Tracts C-a and
C-b, which are considered here, produce results which, in detail, may not be
characteristic of other locations. In addition, changes in development plans,
such as implementation of alternative processes or control technologies, may
alter these assessments.
-------
NEW MEXICO
COLORADO BASIN
BOUNDARY
cn MEVADA
g. . . . s ip is
SCALE IN MILES
DRAINAGE BASIN
BOUNDARY
-------
SECTION 2
POTENTIAL SOURCES OF POLLUTION
AND METHODS OF DISPOSAL
OVERVIEW OF MODIFIED IN-SITU DEVELOPMENT
This study addresses MIS oil shale development such as proposed for Fed-
eral Prototype Lease Tracts C-a and C-b. The MIS process consists basically
of two steps (Figure 2-1): (1) a retort cell is formed by mining 15 to 20
percent or more of the oil shale zone and rubbling the remaining resource
using explosives, and (2) retorting the rubblized oil shale in place (in
situ). In some areas, dewatering of aquifers may be required to accomplish
these operations. The mining and rubbling phase produces sufficient void
space in the retort to allow adequate flow of input and product fluids
through the retort during operation. Combustion is initiated at the top of
the retort by injection of oxygen (air) and heat (e.g., from gas burners).
As the flame front proceeds down through the retort, residual carbon in the
spent oil shale becomes the major fuel source for retorting. After this pro-
cess is sufficiently underway, the external heat source is removed. Inflow
of oxygen (air), is continued and may be mixed with steam or retort off-gas to
control the combustion reaction.
During retorting, the organic kerogen in oil shale is thermally decom-
posed (at 800° to 900°F) to form various hydrocarbon products. An opera-
ting retort is characterized by four zones (Figure 2-1):
• Burned or spent shale zone
• Combustion zone
• Retorting and vaporization zone
• Vapor condensation zone.
During the retort burn sequence, temperatures may reach 2000°F in some
zones.
The products of in-situ retorting include gaseous (off-gas) and liquid
(shale oil) hydrocarbon products, retort water (formed during the combustion-
pyrolysis reaction) and spent or processed shale material. The product gas,
shale oil, and retort water are brought to the surface for use, treatment,
transportation, and/or disposal. The spent shale remains underground.
-------
PRE-RETORT DEVELOPMENT
MINING PHASE
•«—OVERBURDEN-—X\
SUBLEVEL
H {
DRILL
FOR
EXPLOSIVES
SUBLEVEL
RUBBLED RETORT
OPERATING RETORT
AIR
GAS
t
-
BULKHEADS
^^-^fp
ZONE_ - :-'-.
JJ^; CON DENS AT ION ZONE°/
<'r0?r?iio--.'-y.rt«.'"i^.^.'rs .•-»•»• ft".
• ScSi^r-f • »»a:>ftiC?»S MjVrfK ri f :&
Figure 2-1. Generalized development of modified in-situ retort,
The oil shale mined from each MIS retort can be retorted at the surface
(as proposed for the commercial phase of Tract C-a) or disposed on the sur-
face as waste rock.
Potential sources of impact on groundwater quality from MIS development,
such as proposed for Tracts C-a and C-b, are summarized in Table 2-1. Meth-
ods of material treatment, handling, and disposal are also listed. The fol-
lowing discussions provide more detail on these proposed operations.
8
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TABLE 2-1. SUMMARY OF POTENTIAL SOURCES OF GROUNDWATER QUALITY IMPACT,
TRACTS C-a AND C-ba
Source
Waste rock from mine
Tract C-a
| Method of disposal
Surface disposal pile, soil cover,
Amount
~4,000 TPD
Tract C-b
| Method of disposal
Surface disposal pile
Amount
Included under raw
development, etc.
Raw shale'
Dewatering or mine water
Processed shale
In situ
Surface retorting
Retort water
Oily water treatment
Foul (retort) water
stripping
Raw water treatment
revegetation
Surface disposal (MDP, initial
commercial phase)
Surface temporary storage before
retorting during full commercial
operation
- Reinject
- Potable water treatment (Upper
Aquifer water)
- Fire protection, process water,
etc.
- Storage and evaporation
Left in place
- Surface disposal pile
- Slurry injection into abandoned
retorts
Evaporation, combustion, treatment,
and use for dust control or moisten-
ing spent shale
Water to foul water stripping,
sludge to TOSCO II retorts
Distillate to steam generation,
stripped water to shale moistening,
acid gas to sulfur recovery
Line sludge and spent zeolites to
surface of processed shale pile
~36,000 TPD
100,000 tons storage
Dewatering-17 cfs
Mine water seepage-
8 cfs
9.8 to 14.4 x 10°
SIOxlO6 cubic yards
(36,000 TPD)
In situ -57,000 BPSD
Surface retorts ~500
TPD
Water -57,000 BPSD;
sludge unknown
Uncertain; see oily
water treatment
Line sludge 870 TPY;
spent zeolites 3 TPY
shale source
Surface disposal in Cottonwood 41,000 TPD
Gulch, revegetation
- Water treatment for utility, 1,700 gpm
power generation, etc.
-Unlined pond storage; evapora-
tion, reinjection, or treat-
ment and release
- Use for dust control
left in place 1.5 to 2..2 x 10*
No final decision on surface
retorting
Pond storage, evaporation -27,000 BPSD
Pond storage-see retort water Uncertain
Uncertain Uncertain
Domestic water hauled in at Uncertain
present
(continued)
-------
TABLE 2-1 (continued)
Source
Cooling water blowdown
Sanitary wastewater
Oil treatment and
upgrading
Sulfur catalysts from
recovery
Tankage storage
Shale oil
Naphtha
Heavy oil
Gas oil
Fuel oil
Ammonium-nitrate
Runoff
Disturbed areas
Explosives
Tract C-a
1 Method of disposal
Blowdown surge pond, evaporation
Discharge to mine service water
pond, sewage treatment plant
No upgrading except addition of
flow additives
Temporary storage, truck transport;
return to manufacturers when spent
—
--
--
—
--
—
Storage in mine service area
retention pond, evaporation, dust
control, etc.
Most reclaimed (1,454 acres)
Residues left in situ, surface
storage piles
Amount
Unknown
Unknown
—
265 LTPSD; 53 TRY
50,000 bbl
70,000 bbl
140,000 bbl
1,000 bbl
21,000 bbl
525 tons
Variable
1,759 acres
Residue unknown;
52 tons per day
used
Tract C-b
| Method of Disposal
Discharge to lined pond,
evaporation
Unknown
Package plant
None required by FGD
(Ca-sulfite) treatment
Unknown
Storage in catchment ponds,
evaporation, dust control,
compaction of disposal piles
Most reclaimed
Residues left in situ,
surface disposal piles
Amount
100 gpm
Unknown
92.2 LTPSD
Unknown
Variable
1,456 acres
Unknown
These data were taken from the modified development plan submitted by Rio Blanco Oil Shale Company (1977a) and C-b Shale Oil Venture (1977a).
More recent reevaluation and redesign of programs leading to commercial operations are not discussed here in detail. They will be considered
in subsequent phases of this project as they affect potential groundwater impacts and monitoring needs.
-------
DEVELOPMENT SUMMARY—TRACT C-a
Introduction
The developers of Tract C-a, Rio Blanco Oil Shale Project (RBOSP), will
employ a modular program to prove the technical, environmental, and economic
feasibility of the MIS process prior to full-scale commercial operations
(RBOSP, 1977a).
The C-a modular development phase (MDP) was initiated in 1977 to gain
operating experience, improve process efficiency, confirm capital and operat-
ing cost estimates, and verify the environmental integrity of the mining and
processing operations.
The commercial phase is the planned operation of a full-scale commercial
complex beginning in 1987 and continuing for approximately 30 years. Produc-
tion could eventually be approximately 76,000 BPSD, with 57,000 BPSD being
produced by modified in-situ retorting and 19,000 BPSD from surface retorting.
Higher rates of production are, or will also be, considered for Tract C-a.
The 10-year MDP is described in detail in the modified DDP (RBOSP,
1977a). The commercial phase design and operation are conceptual in nature,
but sufficient information is available on the commercial phase for the pur-
poses of this monitoring design study.
RBOSP anticipates modification of operational environmental control and
monitoring programs as necessary to include more efficient ways of developing
oil shale with minimal environmental impact. As stated by RBOSP (1977a),
protection of the three principal components of the environment will be ac-
complished in the following manner:
• Water quality control will be achieved, if feasible, through the
implementation of a zero surface discharge concept.
• Air quality control will be achieved by using equipment and fa-
cilities designed to minimize adverse pollutant emissions and by
applying the best technology available to control any emissions
that cannot otherwise be reduced by design changes.
• RBOSP's objective will be to avoid or minimize land disturbance
wherever practicable. Rehabilitation of disturbed land.will be
undertaken through a program incorporating site preparation,
erosion control, and revegetation.
Detailed plans for groundwater quality control have not been finalized. Op-
tions include spent retort isolation by grouting or other procedures, and
purposeful leaching of the in-situ retort zone (adding water to the burn zone
and recovering leachate for treatment). Such options are being evaluated at
this time, but detailed prediction of results is extremely unlikely due to
lack of experience with the in-situ development operations and the complexity
of the geologic and hydrogeologic system of the Piceance Creek Basin.
11
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Project Description
The proposed development plan consists of a rubblized in-situ extraction
process for recovery of oil from oil shale, a modified sublevel caving method
of mining, on-tract surface retorting, and on-tract disposal of processed
shale (RBOSP, 1977a).
A schematic of the MIS operation envisioned on Tract C-a, including mod-
ular and commercial phases is shown in Figure 2-2. Proposed retort develop-
ment is summarized as follows:
Development phase
Modular
Commercial
Retort no.
1, 2
3, 4
5
6
Dimensions (feet)
30 x
50 x
100 x
150 x
150 x
30 x
50 x
150 x
x
x 750
300
300
140
140
400
700
Plans for the MDP were modified in mid-1979 to include the following re-
tort sequence:
Retort Description (dimensions in feet)
0 30 x 30 x 200
1 60 x 60 x 400
2 Either a pair of 60- x 60- x 400-foot re-
torts burned in sequence or together, or
a single large retort with dimensions of
60 x 150 x 400 feet
3+ Additional retorts as tall as feasible up
to 700 feet (nominal commercial size)
In addition, mining to produce retort void-space will be from a single
sublevel (sublevel 6) at the bottom of the retort rather than from several
sub!eve!s. Blast holes will be drilled from the surface or upper sublevels
through the retort zone. After initial rubblizing, additional rock may be
mucked out to optimize the void volume and rubble size.
Retorts proposed for the MDP will be developed, rubblized, and burned in
a sequential manner as the in-situ process is demonstrated, operational par-
ameters defined, mining methods tested, and the operation generally optimized.
Commercial phase production plans include an equivalent of four retorts
burning simultaneously at an average burn rate of 14 feet per day. Opera-
tions will involve rubblizing retorts, transferring the resulting 20-percent
volume of mined oil shale to a surface ore stockpile, and delivering mine
water, retort exhaust gas, and shale oil to surface transfer points.
12
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co
COMBUSTION AIR SHAFTS
MDP VENTILATION EXHAUST
11MDP SERVICED
AND PRODUCTION
COMBUSTION AIR SHAFTS
R^^^^
(RETORTS 1 THRU 4)
NOTE: SUBSTANTIAL ACCESS WORK HAS BEEN OMITTED
IN THE INTEREST OF CLARITY.
EXHAUSTGAS SHAFT
(RETORTS1THRU4)
Figure 2-2. Schematic layout of mine access and modified in-situ retorts (RBOSP, 1979a).
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Operational options include injection of air alone and air plus steam or
water. Products of MIS retorting are:
• Processed or spent shale (left in situ)
• Shale oil (collected at bottom of retort and pumped to the sur-
face for processing and transportation)
• Retort water {produced on approximately a one-to-one ratio with
shale oil with perhaps some residue remaining in in-situ retort)
• Gas (treated (sulfur removal) and used in gas turbine for
electric power generation).
The 20-percent volume retort material delivered to the surface will be
surface retorted during the coranercial phase in three TOSCO II retorts. Each
TOSCO II retort will be capable of processing 12,000 tons of oil shale to
produce approximately 6300 barrels.of pipelineable shale oil daily for a to-
tal of 19,000 BPSD (RBOSP, 1977a). Other surface retorting processes are
also being evaluated.
On-site treatment of shale oil from both in-situ and surface retorting
will include oil-water separation, addition of flow improvers, and sulfur
recovery.
Figures 2-3 and 2-4 depict the location of proposed RBOSP facilities.
Retorts 1 through 5 in the MPD will be in the shaft pillar in the vicinity of
the MDP service shaft. The prototype commerical retorts in this phase will
be developed in commercial field no. 3 immediately adjacent to the shaft pil-
lar east boundary. Commercial development, beginning in 1987, will commence
in commercial field no. 1 adjacent to and north of the shaft pillar. Subse-
quently, commercial fields 2, 3, and 4 will be developed sequentially. This
commercial phase is anticipated to last 30 years, at which time approximately
one-half of the tract will have been developed.
Surface disposal and storage operations include the following (Figure
2-4):
• Rock from mine development
• R*aw oil shale prior to surface retort construction
• Raw shale prior to surface retorting
• Spent or processed TOSCO shale
• Soil storage.
Investigations are underway to determine if part or all of the processed
shale from surface retorting could be injected into the spent in-situ retorts
by slurrying for the purposes of (1) ground stabilization, (2) sealing the
14
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N 228,000
N223,000
RUN OF MINE
DEVELOPMENT
ORE DISPOSAL
MODULAR
EVELOPW.ENT
PHASE
PROCESSED SHALE
DISPOSAL PILE
CRUSHED
DEVELOPMENT
ORE DISPOSAL
N 2 28,000
|N 223,000
N21 8,000
MILES
Figure 2-3. General location map of Tract C-a facilities (RBOSP, 1977a)
15
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A* PRODUCTION SHAFT
B • SERVICE SHAfT
Figure 2-4. Site plan for Tract C-a development (RBOSP, 1977a).
16
-------
retorts against leaching by groundwater, and (3) disposal of the processed
shale.
Processing, operation support, and other surface facilities include:
• Surface retorts
• Shale oil processing facilities
• Water treatment for mine seepage, potable water, and sewage
• Various water storage and retention basins for runoff, potable
water, process water, and blowdown water
• Gas treatment facilities
* Electric power generation
• Tankage for products, fuel, oil additives, etc.
• Storage for explosives and other materials
• Surface retorts
• Sulfur storage.
Mine dewatering during the modular development and commercial phases
will produce more water than is required for project needs. This excess
water will be reinjected. Up to 100 acre-feet per year of groundwater will
be used during the modular development phase, obtained from mine seepage and
or the dewatering wells. During the commercial phase, approximately 2200
acre-feet per year of groundwater will be used.
Product shale oil will initially be transported by truck and later by
pipeline. Product sulfur will be transported from the tract by truck.
Potential Pollution Sources
A number of components of MIS development such as proposed on Tracts C-a
and C-b have some potential for impact on groundwater quality. The following
identifies the elements of mining, in-situ retorting, surface retorting, and
other surface processing which have such a potential.
Mining-
Included under the heading of mining operations are those activities re-
lated to the development of access to in-situ retorts, development of the in-
situ retorts including excavation and rubbling, and dewatering operations.
Mine access development—During the MDP, mine access tunnels and venti-
lation and service-production shafts will be developed. These operations are
outlined as follows:
17
-------
Dimensions
Sublevel tunnels Either 15- x 12- or 13- x 10-foot
cross sections
Ventilation shaft 7-foot diameter, 1185 feet deep
Service-production shaft 15-foot diameter, 1185 feet deep
Similar operations, but on a larger scale, will be included in the commercial
phase of developments
Dimensions
Sublevet tunnels 25- x 17-foot cross sections
Ventilation shafts Two shafts, 34 feet in diameter;
combustion air shaft, 16 feet in
di ameter
Service-production shaft One shaft, 34 feet in diameter;
one shaft, 24 feet in diameter
The materials excavated during mine access development will be disposed of on
the surface. MDP wastes will be deposited near the modular development area
where they will be contoured, covered with soil, and revegetated. Materials
generated by commercial mine development will probably be treated in a simi-
lar manner.
Retort development—As previously noted, approximately 20 percent of the
retortzone will be excavated during retort development to produce suitable
porosity within the retort. These activities for the original MDP program
are summarized as follows:
Material brought
to surface
Development phase (averagjs TPD)
Modular
Retorts 1-5 500
Retorts 6 and up 3,000
Commercial 40,000
Excavated materials brought to the surface during the MDP will be dis-
posed of at the surface as described above. These oil shale materials will
be crushed and retorted at the surface once commercial feasibility is proven.
During the MDP, up to, 12,000 tons per day will be rubblized in situ for re-
torting. Commercial-scale operations will include in-situ rubblizing of
134,000 tons per day.
18
-------
Beyond surface disposal sites, potential in-situ sources of groundwater
quality impact result from the fracturing within and extending from the re-
tort zone. This potential influence of restructuring of the area hydrogeol-
ogy will not manifest itself during mine development nor retorting due to
dewatering of the operating zone. The effects of such fracturing and re-
structuring may be very significant after retort abandonment and termination
of dewatering.
Dewatering—Mine development, in-situ retort development, and actual
retorting will require dewatering of the operating zone. A dewatering/injec-
tion well program is being developed to support present MDP operations. In
addition, water will be collected within the mine in sumps. This water will
be reinjected, stored, and used for dust control or other purposes, or re-
leased to surface streams.
In-Situ Retorting—
During retorting, in-situ retorts themselves probably do not pose a
great threat to groundwater systems. This is because dewatering operations
will hydro!ogically isolate the retorting zone and temperatures within the
retort will preclude the presence of liquid water. However, the products of
in-situ retorting which may remain in the subsurface are appreciable poten-
tial pollution sources after abandonment. Items of importance in this regard
include:
• Escape of retort gases, shale oil products and retort water into
the aquifer zones around the retort (Tract C-b developers have
indicated that retorts will be kept under negative pressure un-
til cooled below 212°F to avoid this problem)
• Residual materials (gases, shale oil, retort water, spent shale)
remaining in the retort after completion of the production burn
• Release of shale oil or retort water during transport within the
mine
• Expansion of fractures (natural or created during rubbling of
the retort) during retorting by temperature or pressure stresses,
or due to subsidence or related failure of the retort walls.
The mass of material (i.e., potential pollutants) associated with this
source is unclear. Oil, gas, and retort water are to be brought to the sur-
face to be treated and transported or disposed.
As indicated above, MIS retorting becomes a significant potential pollu-
tion source after abandonment of the in-situ retorts. Eventually, dewatering
of the retort zone will be terminated, allowing recovery of water levels in
the aquifers adjacent to the retort zone. Interconnection of abandoned in-
situ retorts and the adjacent aquifer system is not a certain event, but it
is a highly likely event. Water entering abandoned retorts may result in the
following:
19
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* Aquifer interconnection through retorts and mine tunnels and
shafts
• Leaching of inorganic and organic materials remaining in the
retort
• Possible further restructuring of the hydrogeologic system due
to the effects of water saturation on the structural integrity
of spent shale and retort walls.
The amount of spent shale in spent retorts is as follows:
Development Mass of spent shale
phase Retort Dimension (feet) (104 tons)*
Modular 1, 2 30 x 30 x 140 0.8 - 1.14
3, 4 50 x 50 x 140 2.2 - 3.3
5 100 x 150 x 400 18.7 - 27.3
6 150 x 300 x 700 98.1 - 144.0
Commercial -- 150 x 300 x 750 105.0 - 154.Of
Surface Retorting--
Eventual commercial-scale operations on Tract C-a include surface re-
torting of oil shale mined during development of in-situ retorts. Potential
pollution sources associated with surface retorting include:
• Raw shale stockpile (100,000 tons)
• Retort water
• Processed shale.
Raw shale will be stored only temporarily prior to retorting. However, some
potential exists for leaching of soluble materials during storage. Develop-
ment plans call for evaporation/combustion of retort waters using a thermal
oxidizer.
Processed shale will be disposed of at the surface and will be revege-
tated. One alternative currently being studied is the injection of slurried
* Range of estimates listed result from range of bulk density data used. A
bulk density of 1 gm/cc for in-situ spent shale from Amy (1978) is a lower
end of range. Margheim (1975) indicates an in-place rock density of 2.3
gm/cc. Removal of 20 percent of mass before rubblizing and another 20
percent during retorting yields a bulk density of 1.46 gm/cc. This value
was used for the upper range estimate.
^ 932 retorts, over a 30-year development, yield approximately 9.8 to
14.4 x 10^ tons of in-situ spent shale.
20
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processed shale into abandoned in-situ retorts to aid in sealing and stabili-
zing. If slurry injection is not feasible, spent shale from the surface re-
torts will be transported via conveyor belt to the disposal area where it
will be spread and compacted. The spent shale, moisturized to about 15 per-
cent (by weight) is expected to have a compacted density of 85 pounds per
cubic foot. The total compacted volume will be 310 million cubic yards.
Surface Processing--
Surface processing (Figure 2-5) includes the following elements:
• Raw water treatment
• Retort water treating (oil-water separation and foul water
stripping)
• Power and steam generation
• Oil treatment and upgrading
• Gas treatment
• Waste water (sewage) treatment
• Tankage.
Raw water treatment (Figure 2-6) will include hot lime and hot zeolite
softening. Lime sludge wastes (870 tons per year) will be dewatered using
the thermal oxidizer and subsequently deposited in solid waste landfills in
the processed shale pile. Regenerant brines from the hot zeolite process
will be transported to a blowdown sludge pond. Spent zeolites (3 tons per
year) will also be deposited in spent shale pile landfills.
.Retort water will be separated from shale oil product utilizing an API
separator (skimming) system (Figures 2-5 and 2-6). Oily waste water from the
API system will be discharged to the process area retention pond and subse-
quently used for dust control. Other retort waters from the oil recovery and
retort-gas condensate will be treated in the foul water stripper, with dis-
tillate going to steam generation, and stripped water will be used for shale
moisturizing.
Power generation and other process equipment will require cooling water
which will be obtained from mine seepage and the potable water treatment sys-
tems. Blowdown from cooling water and boiler systems will be discharged to
the blowdown surge pond and subsequently evaporated (Figure 2-6).
After retorting product fractionation (into water, gas, and oil), the
oil will be fractionated into naphtha and heavy oil fractions. The gas will
be compressed, treated for sulfur removal, and used as a fuel to produce
electric power. Heavy oil will be treated as required with flow-improving
chemicals and blended with naphtha and 04 fractions to produce pipeline-
quality oil (Figure 2-5).
21
-------
FLUE GAS
ro
rvi
ELECTRIC POWER
FOR PLANT USE
PIPELINE QUALITY
OIL PRODUCT
PROCESSED SHALE
Figure 2-5. Flow diagram of commercial phase processing facility (RBOSP, 1977a).
-------
ro
CO
DEWATERING
WELLS UPPER
AQUIFER
UPPER
AQUIFER
REINJECTION
MINE SERVICE
AREA
RETENTION
POND
MINE SERVICE
AREA
RUNOFF
DEWATERING
WELLS LOWER
AQUIFER
BLOWDOWN
SURGE POND
LOWER
AQUIFER
REINJECTION
PLANT SITE
RETENTION
POND
PLANT SITE
RUNOFF
COOLING
TOWER
1 EVAP.
i f
DISPOSAL
AREA RUNOFF
& LEACHATE
MIS
RETORT
WATER
WATER
TREATMENT
RINKY DINK
RESERVOIR
PROCESSED SHALE
DISPOSAL COMPACTION
SHALE
MOISTURIZING
DUST CONTROL
SPRINKLING
NORMAL FLOW PATH
IF NEEDED
Figure 2-6. Water flow schematic for Tract C-a development (RBOSP, 1977a).
-------
The byproduct of gas treatment and the TOSCO process is elemental sulfur.
A total of 265 long tons per day will be produced by the full commercial-scale
operation.
Sanitary wastes will be handled by a sewage treatment plant with treated
discharge to the mine service area retention pond for subsequent use in dust
control, fire control, etc.
Diesel fuel and gasoline will be stored in buried tanks. Motor oil and
other fluids will be stored in the durable containers in which they are
shipped.
Annual amount in gallons
Products Modular development phase Commercial phase
Diesel fuel 1,055,000 5,900,000
Gasoline 46,000 135,000
Motor oil 15,000 45,000
Other lubricating oils 1,500 5,000
Hydraulic fluid 18,000 52,000
Antifreeze 200 500
During the MDP, a service station will be provided at the mine service area
in conjunction with the storage tanks and delivery facilities. Additional
service stations with tankage will be provided for the commercial phase at
the processed shale disposal area equipment shop and at the processing area
maintenance shop.
Waste motor oil will be collected and mixed with diesel fuel. Used
antifreeze will be discharged to the sanitary sewer system. Sludge from
diesel tanks, waste hydraulic fluid, and other waste oils will be burned in
the thermal oxidizer.
Oil and Hazardous Material Control--
The oil and hazardous material control plan has been formulated recog-
nizing that the best control plan is prevention of spills through proper
design of storage, handling, and transporting facilities. However, a spill
contingency plan will be implemented during all phases of the project, estab-
lishing procedures to be followed to minimize damages in the event of acci-
dental spills.
This spill contingency plan includes procedures for notification, con-
tainment, repair, and cleanup of spills. The primary objective is to mini-
mize, as far as practicable, any damage from a spill to persons, property,
flora, and fauna.
The layout and construction of tanks, valves, piping, and appurtenances
will be designed to minimize the possibility of spillage. Tanks will be
24
-------
enclosed by dikes designed to form spill-containment basins. The drainage
from these diked areas will enter the processing facility storm drainage sys-
tem and pass through an API oil separator. Catchments will be constructed in
any natural drainages immediately downhill from the oil storage facilities so
that should any oil find its way outside containment facilities, it can be
easily controlled before it reaches a water course.
Contingency plans for the MIS underground oil/water pumproom will cover
design (grading, emergency equipment and facilities, control and warning sys-
tems, etc.), operating guidelines, and spill response guidelines.
A detailed spill contingency plan will be developed for both
nontransportation- and transportation-related facilities. This plan will
include procedures to be followed in the event of a spill detection and will
include procedures for system shutdown, notification, reporting to Federal
and State agencies, internal reporting, containment of the spill, removal of
spilled material, and cleanup and restoration of the contaminated site.
Land Rehabilitation and Erosion Control—
The objectives of the land rehabilitation program are to reclaim dis-
turbed areas by returning them to a state that does not contribute to envi-
ronmental deterioration and is consistent with surrounding aesthetic values.
The overall concept of rehabilitation efforts for the project includes nu-
merous problems and considerations dealing with mining access, plant sites,
parking lots, conveyor corridors, access roads, pipelines, etc. The prin-
cipal elements considered are site preparation, erosion control, and
revegetation.
Table 2-2 shows estimates of the yearly disturbed surface areas and
areas ready for rehabilitation for the operation. The Rangely access road,
power line, and telephone line are excluded because they will be constructed
and rehabilitated by other entities, i.e., Rio Blanco County, Moon Lake Elec-
tric, and Mountain Bell.
Site preparation, or the shaping and grading of areas being rehabili-
tated, is controlled by three primary environmental concerns: erosion con-
trol, aesthetics, and the plant species to be supported. One additional
factor influencing the rehabilitation work is the method selected for con-
structing an artificial soil profile on the processed shale disposal pile to
facilitate revegetation.
Surface runoff will be controlled throughout the project area. Diver-
sions around the mine, processing facility, and processed shale disposal pile
will be provided. Surface water originating outside the project area will be
diverted completely around RBOSP facilities and returned to an existing water
course downstream. Surface runoff originating within the RBOSP area will be
controlled and will not be released to downstream water courses unless its
quality is shown to be adequate.
25
-------
TABLE 2-2. ESTIMATED ACREAGES OF LAND SCHEDULED TO BE DISTURBED AND REVEGETATED
ON TRACT C-a (RBOSP, 1977 a)
ro
Disturbed:
Mine and
plant sites
Run of mine
disposal area
Crushed ore
disposal
Corridors
Processed shale
disposal pile
Reclaimed:
Run of mine
disposal area
Crushed ore
disposal
Corridors
Processed shale
disposal pile
1987- 1992- 1997- 2002- 2007- 2012-
1978 1979 1980 1981 1982 1983 1984 1985 1986 1991 1996 2001 2006 2011 2016 Total
34 26 218 278
65 65
130 130 26Q
100 12 21 39 104 276
70 320 210 40 240 88°
199 12 47 257 130 130 70 424 210 40 240 1759
15 20 30 65
200 60 260
80 12 21 32 104 249
20 215 215 215 215 88°
80 12 36 52 30 200 104 20 215 215 215 275 1454
-------
Water Supply and Demand—
Water supply--The water supply for development of Tract C-a will come
from mine dewatering systems, water produced by the MIS retorting operation,
and surface drainage water.
As now planned, the MDP mine dewatering system will consist of separate
wells for the Upper and Lower Aquifers and mine seepage. Dewatering during
this phase will vary widely but should always be in excess of requirements.
The project water requirements from dewatering systems will be approximately
1000 acre-feet per year.
The mine dewatering system will be continually modified with the addi-
tion of new wells and abandonment of old ones as the underground mine area
grows throughout the commercial phase operations. Mine dewatering is ex-
pected to produce about 18,000 acre-feet per year. Water requirements from
dewatering systems will be approximately 2200 acre-feet per year. Excess wa-
ter produced from dewatering well and mine seepage will be reinjected to re-
duce the overall effect on the groundwater aquifers.
Water demand—Estimated water usages (in gallons per minute) for the
modular development and commercial phases are shown as follows:
Modular
development Commercial
Use phase phase
Processing* 710
Potable 35
Dust control and miscelleanous 220
Total 965
Processing uses include water for boiler feed, cooling, moisturizing
processed shale, operation of retort scrubbers, disposal of MIS retort water,
and miscellaneous uses.
DEVELOPMENT SUMMARY—TRACT C-b
Project Description
The development of the commercial MIS facilities is shown on the project
plot plan (Figure 2-7). The Tract C-b development program will extend from
September 1, 1977, starting with site preparation, to September 1982, when
the mine and surface facilities will be capable of full-scale production.
The property will be mined by developing successive geographic areas
called panels. A commercial panel will consist of 32 clusters with 8 retorts
* Does not include water of combustion.
27
-------
PO
CD
• •••••»»»»»P»Ll*Jt «««"*»•*"
^^IMPOUNDMENT POND
RETORT FIELD
'•i
WASTEWATER POND
SUPPORT AREA
WATER TREATMENT
Figure 2-7. Plot plan for Tract C-b development (from C-b Oil Shale Venture, 1977a).
-------
per cluster. At a production rate of 57,000 barrels per day, a commercial
panel will take 4 years to develop completely. An equivalent of 15 panels is
proposed for Tract C-b totaling 3840 individual retorts with dimensions of
200 x 200 x 310 feet. Forty retorts will operate simultaneously during full
commercial production.
Using the range of bulk density of 1.0 to 1.46 gm/cc for spent shale,
this commercial operation is estimated to produce from 1.5 to 2.2 x 10^
tons of in-situ spent shale.
Site Preparation and Shaft Sinking—
The first site activities starting in September 1977 will be shaft sink-
ing for mine access. At the same time, certain site preparation and precon-
struction activities will proceed, including preparation or extension of
service roads, construction of water storage to receive underground water
from initial dewatering operations, and necessary grading for temporary con-
struction facilities, fencing, etc.
Full-Scale Modified In-Situ Plant and Operations—
The construction period of the full-scale commercial facility will begin
with shaft sinking in September 1977 and end September 1982 when the first
cluster within the commercial panel is kindled. The construction of the ma-
jor oil/gas processing units and general facilities will occur between Janu-
ary 1981 and September 1982. As more clusters are brought on-line, production
will increase and full-capacity production (57,000 barrels per day) will be
achieved in about 12 months, or by September 1983 (Figure 2-7). Operations
will continue from September 1982 to about the year 2040, when the resource
interval will be exhausted.
An ancillary development site located near the north-central border of
Tract C-b had initially been proposed. This facility was to include two or
more commercial-si zed retorts, retort clusters, and associated operating
equipment. This development was proposed to establish environmental monitor-
ing procedures, obtain operating experience, and provide for training of per-
sonnel. Tract development plans now include initial retorting operations
within the commercial mine complex described above and illustrated in Figure
2-7.
Potential Pollution Sources
The basic nature of the MIS development operations proposed for Tract
C-b is the same as that described above for Tract C-a. The major differences
are the Tract C-a MDP and the surface retorting of mined oil shale, which
have no present counterpart in Tract C-b.
Hence, potential sources of groundwater quality impact identified for
Tract C-a MIS development are also characteristic of Tract C-b development
plans. Some differences do exist with regard to the mass of materials in-
volved. The following is a brief description of the retorting process (C-b
Oil Shale Venture, 1977a).
29
-------
The processing of a cluster of retorts consists of several steps. First,
a retort within a cluster is kindled from the top by externally fueled burn-
ers. When the temperature at the top of the retort is sufficient to sustain
reaction, the burners are shut off and a regulated mixture of air and steam
is drawn into and through the retort by exhaust blowers on the surface. Re-
sidual organic material is combusted with the air in the feed gas. The hot
combustion gases flow down through the retort and supply heat to the raw, un-
retorted shale below. As the shale is heated, the organic material, or kero-
gen, decomposes into oil vapor and other gases that are carried along with
the combustion gases, while some residual organic material remains in the
rubble. Steam in the feed gas acts as a diluent to the oxygen in the air to
control the reaction temperature and reacts with some of the residual organic
material, forming carbon monoxide and hydrogen to improve the heating value
of the product gas. Some of the mineral carbonates in the shale are also de-
composed to carbon dioxide gas and mineral oxides. As the gas mixture flows
down through the retort, it preheats the raw shale. At the same time, the
oil and some of the water vapor are condensed. Product liquids and gas leave
the bottom of the retort and move to the surface for further processing as
product oil, fuel gas, and water.
As the retorting progresses, the combustion and retorting zones move
slowly down through the in-situ retort. Between 7 and 8 months are required
to process a cluster. When retorting is complete, the air and steam feed are
stopped and the in-situ retort is closed off. The spent shale remains under-
ground with no need for surface disposal.
Surface process facilities consist only of oil/water separation equip-
ment, exhaust blowers, a sulfur removal unit for treatment of product gas,
and boilers to produce process steam from the product gas.
A block diagram of the C-b commercial phase operation is shown in Figure
2-8. Details not available on development plans include the characteristics
of treatment and disposal and sizing for the following:
• Retort water
• Oil treatment or upgrading on site
• Tankage on site.
Water Supply and Demand-
It is anticipated that water available from the mine will be more than
required by the C-b operation during early stages of development, but slightly
less than required for full commercial operations:
30
-------
MINE MINED SHALE
41,134 TPD
• »-* MINE WATER
TO POND ^ " 1700 gpm
[or Alternatives) * ( ' *
j i
RETURN 300 gpm
CONDENSATE
MAKFUP 100 to 500 gpm
TO GENERAL 100,000 Ib/hr STEAM
FACILITIES "* !
<>-< 848,000 Ib/hr
999.9 MMSCFD nf-mn-r,*,~ GAS PRODUCT
Ain _,. , . w RETORTING .M.,,,,.^^ h
"'" " ~ 1573.2MMSCFD "
fDRY)
FILL
WATER
TREATMENT
i
r
STEAM
GENERATION
PLUS THERMAL
OXIDIZER
i
i
GAS
TREATMENT
'l START UP OIL
122 BPD
LIQUID PRODUCT
83,465 BPD
300 gpm ^ UTILITY USE
1874.1 MMSCFD A1D
3454.0 MMSCFD CTrini, ,-,»<.
>•- STOCK GAS
(TOTAL)
y. BLOWDOWN
100 gpm "~ JO POND
TREATED GAS
1570.7 MMSCFD
(DRY)
92.2 LTPD
'^" oULI Ull
OIL/WATER
SEPARATION
56,996 BPD PRODUCT OIL
*" 56,874 BPD
772 qpm
_ . — , , — ?K w., I/I/ATPR rn nr\
Figure 2-8. Flow diagram for Tract C-b commercial operations (C-b Oil Shale Venture, 1977a),
-------
Status of mine and process plant
Initial retort development
Retort cluster development
Commercial operation
Estimated mine
water available
(gpm)
400 - 1,000
800 - 2,000
2,000 - X
Estimated mine and
process water
usage (gpm)
310
460
2,500
If a surplus of water occurs, the excess will be stored and then either rein-
jected or treated and released.
During shaft-sinking and the initial retort period, a surplus of water
of from 100 to 700 gallons per minute is anticipated based on preliminary
hydrologic studies. This water, depending on final quantity, will be either
stored for later use or disposed of by evapotranspiration, reinjection into
aquifers, or treated and released to surface streams.
An existing pond in Cottonwood Gulch (see Figure 2-7) will provide ini-
tial storage for water during development. A temporary impoundment north of
the Cottonwood pond at the edge of the tract can also be used to store water,
if necessary, until the Sorghum Gulch Dam is constructed or other options, as
discussed above, are exercised.
During the first retort cluster period, anticipated water surplus over
requirements (see Figure 2-8) will be from 500 to 1500 gallons per minute.
Surface storage volume will increase as construction of the Sorghum Gulch Dam
(Figure 2-7) and the gas treatment area impoundment pond are completed. The
Sorghum Gulch Dam will be of earthfill construction and constructed to a
height of approximately 80 feet. The dam will enable productive use of the
rock excavated during surface facility and mine shaft construction, and will
provide a water containment system for storm runoff from the construction
area and serve as a storage system for groundwater produced from shaft-
sinking and development mining activities. The impoundment will have a max-
imum capacity of approximately 600 acre-feet. The dam site will require ap-
proximately 6 acres of land.
A coronation diversion system will be used to divert rainwater around
the shale disposal area and into the dam impoundment. Additional catchment
ponds may be installed above the Sorghum Reservoir to capture sediment from
the shale and prevent it from reaching the reservoir. Water from the catch-
ment ponds will be used to supplement needs for shale dust and compaction
control.
It may be found necessary to retain and make permanent the Cottonwood
Gulch temporary impoundment pond constructed earlier to collect runoff from
the plant area drainage system. This water, depending on quality, would
either join the Sorghum Reservoir water or be added to the lower-quality
water for shale use.
32
-------
The lined pond adjacent to the gas treatment area would revert from gen-
eral water storage use to its final service as containment settling and con-
centration area for product water and process blowdowns.
Land Disturbance-
Estimates of land disturbance due to Tract C-b development and operation
are summarized in Table 2-3.
33
-------
TABLE 2-3. ESTIMATED SURFACE DISTURBANCE BY YEAR AND OVERALL (acres)
co
Activity
Mine development:
Surface facilities (15-ft
shaft)
Steam generation
Gas treatment
Cottonwood Gulch:
Mined rock fill area
Impound pond
Road construction:
Tract access
Service
In situ gas treatment
facilities
Mine production and
service shaft area
Sorghum Gulch:
Dam site
Reservoir
Shale storage area
Year 11
Year Year Year Year Year Year Year Year Year Year to
1 23456789 10 Year 2005
8
3
3
15 20 75 100 100
4
8 20 25
3 5
44 30
15 15
3
3 17
100 100 100 100 540
Total
by
activity
8
3
3
310
4
53
8
74
30
3
20
940
Total by year
(accuracy of estimate
±25 percent)
40 114 162 100 100 100 100 100 100
540
1,456
-------
SECTION 3
POTENTIAL POLLUTANTS
In the preceding section, potential sources of groundwater quality im-
pact were identified. The potential pollutants associated with these various
sources are the subject of this section. This discussion focuses on modified
in-situ retorts. Consideration of surface operations may be found in the
initial project report dealing with the Utah Federal Lease Tracts U-a and U-b
(Slawson, 1979).
RETORT WATER
The major potential pollution sources associated with in-situ retorts
are the retort water and the in-situ spent shale. Available data related to
characterizing these sources are presented in the following discussion.
Retort or process waters from in-situ retorts will be for the most part
brought to the surface with other liquid products to be treated, used, or
disposed. In addition, it may be expected that some of these waste waters
will remain in the spent retorts. Retort waters are of particular importance
as potential pollutant sources because the volume produced is expected to be
roughly equivalent to the volume of shale oil produced. The origin of these
process waters is combustion in the retort, dehydration of minerals, and lo-
cal groundwater. Thus, the exact composition will be site specific and vari-
able. These waters are described as brown to yellow in color with alkaline
pH and high levels of inorganics and organics. Major inorganics include bi-
carbonates, carbonates, fluoride, magnesium, sodium, sulfate, and ammonia.
Organics are dominated by polar (e.g., carboxylic acids) consituents.
Table 3-1 lists the results of analysis of waters from several different
simulated in-situ retorts. The reported data are from several simulation ex-
periments (performed in aboveground vessels of laboratory or pilot scale) and
the analyses were performed by several different laboratories. Also presented
are the results of a single sample from an MIS retort developed by Occidental
Oil Shale, Inc.
Table 3-2 lists the results of analysis of retort water obtained from
true in-situ tests at Rock Springs, Wyoming. Although this retorting approach
is different from MIS retorting, the combustion character of both processes
is similar and thus results should be applicable to MIS development. Again,
data from MIS retort no. 6 at Logan Wash are provided here for comparison.
General agreement can be seen with regard to levels of total dissolved solids,
sodium, potassium, organic carbon, organic nitrogen, and many trace metals.
35
-------
TABLE 3-1. CHEMICAL CHARACTERIZATION OF SIMULATED AND OBSERVED
IN-SITU OIL SHALE PROCESS WATER
Constituent
General water quality
measures
Total alkalinity (CaC03)
Conductivity (ymhos/cm)
Hardness (CaCOg)
pH (pH units)
Solids, dissolved
Solids, total
Major inorganics
Bicarbonate
Carbonate
Chloride
Fluoride
Sulfate
Sulfide
Anmoni a-N
Ammonium-N
Nitrate-N
Nitrite-N
Silica (Si02)
Calcium
Magnesium
Sodium
Potassium
Organics
5 -day BOD
Organic C
Organic N
Minimum
18,200
15,100
20
8.1
1,750
6,350
4,200
0
0.007
0.1
42
0
1,700
930
1.4
<1.0
4
0
3.2
45
8
350
2,200
733
Concentration
(mg/l)a
Maximum Median'5
110,900
193,000 31,
1,500
9.4
24,500 6,
121,000
73,640
15,210
1,910
270
2,200 1,
156
13,200 7,
23,450 10,
8.7
—
128
94
350
1,600
120
5,500
19,000 4,
1,510
000
88
8.7
800
—
—
—
—
400
—
000
000
—
—
17
7.6
22
320
37
—
700
—
Retort no. 6C
540
— ^ —
13,000
13,000
659
<1
240
15
4,000
—
3.1
—
62
—
16
150
140
3,700
61
—
986 (DOC)
451
(continued)
36
-------
TABLE 3-1 (continued)
Concentration (mg/l)a
Constituent
Organics (continued)
Oil and grease
Phenols
Volatile solids
Volatile acids
Trace elements
Arsenic
Barium
Beryl 1 i um
Bromi de
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Vanadium
Zinc
Minimum
3,800
2.2
2,070
807
0.46
0.002
<0.001
<0.001
<0.001
0.009
0.002
0.003
0.091
0.002
0.001
0.001
0.033
0.014
<0.001
<0.001
0.004
0.020
Maximum
3,800
169
119,300
1,481
10
0.47
<0.001
1.94
0.005
0.08
0.65
160
77
0.83
0.39
0.39
1.2
2.6
1.7
0.23
>190
15.1
Median^
—
—
—
—
1.8
0.07
—
0.082
—
0.015
0.12
0.019
7.6
—
0.099
—
—
—
—
—
0.27
0.28
Retort no. 6C
30
8.7
—
—
0.07
0.8
—
—
<0.2
—
—
<0.2
2
—
<0.2
<0.2
10
0.1
<0.2
—
—
0.1
aFrom Fox et a!., 1978a.
^50-percent probability of occurrence less than or equal to reported concen-
tration; reported only when sample size was more than 15.
cSingle sample, retort no. 6, Occidental Logan Wash (DA) Project, Septem-
ber 29, 1978. Presented here for rough comparison; does not necessarily
represent expected values.
37
-------
TABLE 3-2. CHARACTERIZATION OF RETORT WATER FROM (TRUE IN-SITU)
RETORT NO. 9, ROCK SPRINGS, WYOMING, AND FROM MODIFIED
IN-SITU RETORT
Constituent
General water quality measures
Total alkalinity (CaC03)
Conductivity (umhos/cm)
Hardness (CaC03)c
pH (pH. units)
Solids, dissolvedd
Solids, total
Major inorganics
Bicarbonate
Carbonate
Sulfate
Sulfide-S
Tetrathionate (S^OJT)
Thiosulfate (Sp03)
Thiocyanate (SCN~)
Ammonia-N
Ammon i um-N
Nitrate
Chloride
Calcium
Fluoride
Magnesium
Potassium
Sodium
Organics
5-day BOD
Organic C
Organic N
Oil and grease
Phenols
Cyanide
Concentration
Rock Springs
retort no. 9
16,000 ± 500
20,400 ± 3,840
110
8.65 ± 0.21
14,210 ± 223
14,210 ± 120
15,940
500
1,910 ± 130
0
280
2,740 ± 730
136
3,830 ± 435
3,470 ± 830
0.17
764 ± 92
12 ± 4
62 ± 9
20 ± 6
46 ± 10
4,265 ± 272
740
1,030 ± 105
148 - 630
580
64 ± 34
0.42 - 0.90
(mg/1)
Logan Wash .
retort no. 6
540
13,000
13,100
659
<1
4,000
—
___
748
—
3.1
___
62
240
150
15
140
61
3,700
—
986 (DOC)
451
30
8.7
—
(continued)
38
-------
TABLE 3-2 (continued)
Constituent
Trace elements
Arsenic
Barium
Beryl 1 i urn
Boron
Bromi de
Cadmium
Chromium
Cobalt
Copper
Iron
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Vanadium
Concentration
Rock Springs
retort no. 9
1.0 ± 0.2
0.71 ± 0.33
<0.006
27 ± 7
2.3 ± 0.4
0.0016 ± 0.0008
0.02 ± 0.01
0.025 ± 0.016
0.09 ± 0.05
1.2 ± 0.3
0.09 ± 0.04
0.003 - 0.'021
0.57 ± 0.16
0.06 ± 0.02
0.20 ± 0.12
0.003 ± 0.001
0.12 ± 0.01
(mg/1)
Logan Wash .
retort no. 6
0.07
0.8
—
<0.04
___
<0.02
—
___
<0.02
2
<0.02
<0.02
10
0.1
<0.02
—
—
aBest value concentration determined as follows (from Fox et a!.,
1978a):
1. Smallest upper limit is reported unless that upper limit is
for spark-source mass spectrometry analysis (SSMS); SSMS
upper limit multiplied by three
2. Range is reported if coefficient of variation is greater than
100 percent
3. Single measurements shown as such and used as best value
4. Best values based on two or more measurements determined by
Dixon's procedure after exclusion of values concluded to
result from analytical error. Reported error is one standard
deviation where more than one measurement made, otherwise
estimated laboratory error reported.
''Single sample, retort no. 6, Occidental Logan Wash (OA) Project,
September 29, 1978. Presented here for rough comparison; does not
necessarily represent expected values.
cFrom Ca and Mg analysis.
^See Fox et al, 1978a for method of estimating carbonate species
distribution.
39
-------
However, these results show appreciable differences in ionic composition as
the Logan Wash retort water showed considerably lower levels of alkalinity
(and bicarbonate), thiosulfate, ammonia, chloride, fluoride, oil and grease,
and phenols, with considerably higher levels of sulfate, nitrate, calcium,
and magnesium. Differences in oil shale retorted, retorting conditions, and
perhaps analytical procedure contributed to these differences.
Fox et al. (1978a) discuss analytical problems associated with the char-
acterization of retort waters. They conclude that:
• Significant problems exist with use of standard analytical tech-
niques for complex waters such as retort waters
• Instrumental methods are generally more accurate than chemical
methods
• Sample handling can appreciably affect results
• Existing methods may be adequate for the measurement of sulfate,
inorganic carbon and ammonia
• Methods development is needed for routine measurement of cya-
nide, COD, phenols, orthophosphate, solids, and sulfide.
For the alternative analytical methods evaluated, the following was concluded:
• Spark source mass spectrometry produced lowest detection limits
but poorest precision
• X-ray fluorescence and neutron activation analysis produced pre-
cise and accurate results
• Atomic absorption is acceptable for measurement of Ca, Mg, Fe,
Na, Si, As, K, Se, and Zn.
Some of the other available data on the chemical characteristics of in-
situ retort water are listed in Table 3-3. Of particular note here is the
wide differences between simulated in-situ retort water and that collected at
Rock Springs from true in-situ retorts. This is particularly true for con-
ductivity, sodium, bvcarbonate, carbonate, fluoride, organic carbon (DOC),
and organic nitrogen (Kjeldahl nitrogen).
IN-SITU SPENT SHALE
In addition to retort water, a significant source of groundwater impact
is the materials which may be leached from abandoned in-situ retorts into ad-
jacent aquifers. A summary of the characteristics of these potential contam-
inants is presented in the following paragraphs.
Amy, Thomas, and Hines (undated) evaluated the leaching of organics from
shale retorted in a simulated in-situ retort. Both inert (N2) atmosphere
and combustion retorting conditions were considered. Only the combustion
40
-------
TABLE 3-3. CHARACTERISTICS OF IN-SITU RETORT WATER REPORTED
IN AVAILABLE LITERATURE
Constituent
Total dissolved solids
Conductivity (umhos/cm)
pH (pH units)
Calcium
Magnesium
Potassium
Sodium
Bicarbonate (HC03)
Carbonate (C03)
Concentration (mg/1)
3,000
25,000
48,000
8.5 - 9.5
8.5
8.6
8
4
12
16
43
24
3,100
4,100
188
15,000
33,400
19,200
2,100
14,900
Reference9
b
c-1
c-2
b
c-1
c-2
c-1
c-2
c-1
c-2
c-1
c-2
a
c-1
c-2
c-1
c-2
.a
c-1
c-2
(continued)
41
-------
TABLE 3-3 (continued)
Constituent
Chloride
Sulfate (S04)
Fluoride
Thiosulfate (S^OI)
Ammonia -- NH-
NH3
NH+-N
TOC
DOC
COD
Total Kjeldahl nitrogen
Concentration (mg/1)
13,410
3,900
2,800
4,450
1,400
1,340
56
12
3,000
2,050
4,800
2,500
3,800
2,150
1,000
5,000
6,700
4,000
18,000
Reference3
a
c-1
c-2
a
c-1
c-2
c-1
c-2
c-1
c-2
a
b
c
b
c-1
c-2
b
c-1
c-2
References:
a - Hubbard (undated), water from Rock Springs tests
b - Pfeffer (1974), simulated in-situ data
c - Stuber and Leenheer (1978): data from Rock Springs No. 9
test (c-1), and simulated in-situ (LERC 150-ton) retort
(c-2)
42
-------
retorted shale experiments will be considered here, as these most closely
correspond to proposed MIS operations on Tracts C-a and C-b. Experimental
characteristics are as follows:
Experiment no. Retort 1 Retort 3
Input gas Air + N? Air + recycle gas
(7.6% 02) (10.5% 02)
Maximum retort temperature
(°C) 750 935
Retorting rate
(meters per day) 0.69 1.34
Spent shale organic content
(percent by weight) 0.2 2.1
The relatively low organic levels in spent shale 1 result from combus-
tion of residual organics during retorting. The elevated levels in spent
shale 3 are due to adsorption or condensation of organics from the recycle
gas behind the flame front in the retort.
Thirty-day batch leaching experiments using varying water temperatures
(approximately room temperature and 80°C to simulate water entering an un-
cooled retort) and varying water quality (distilled water and simulated
groundwater, intended to approximate Lower Aquifer water from the Piceance
Basin), were conducted:
TOG (milligrams per 100 grams spent shale)
Temperature
Leaching water (°C) Shale 1 Shale 3
Distilled 20 1.1 3.5
Distilled 80 1.3 2.9
Synthetic
groundwater 20 1.0 3.8
Synthetic
groundwater 80 1.0 3.4
No great differences can be seen in leachate quality due to changes in either
water temperature or initial water quality.
Equilibrium batch experiments, wherein varying amounts of leachate water
were added to processed shale and allowed to equilibrate, were also conducted
with the following results from spent shale 1:
Mass spent shale '(grams) 50 50 50 50
Volume water added 30 50 100 200
(mill il Hers)
43
-------
Temperature
Leaching water (°^C) TOC (milligrams per 100 grams spent shale)
Distilled 20 1.1 1.1 1.0 1.6
Distilled 80 1.0 1.3 1.4 2.0
Synthetic
groundwater 20 1.1 1.0 1.4 1.4
Synthetic
groundwater 80 1.0 1.0 1.5 1.8
Using estimates provided earlier of the amounts of spent shale to be
left in place on Tracts C-a and C-b, the following amounts of potentially
Teachable carbon are estimated:
Amount in-situ Assumed Teachable LeachabTe
Tract spentshaTe (tons) amount (mg/100 g) amount (tons)
C-a 9.8 - 14.4 x 108 2.0 2.0 - 2.9 x 104
C-b 1.5 - 2.2 x 109 2.0 3.0 - 14.4 x 104
Other observations reported by Amy and Thomas (undated) on the above and
a series of continuous flow experiments indicated that the leaching of organ-
ics was also influenced by particle size. Because a greater surface area is
available for leaching, smaller particle sizes yield more leached materials.
Also, the amount of organic matter leached (i.e., TOC concentration) gener-
ally increased with time as did inorganics (as indicated by increasing speci-
fic conductance), although minor decreases were also noted occasionally. In
general, during the continuous flow experiments, the rate of leaching was
greatest during the first day with approximate equilibrium being reached by
the tenth day.
At the tenth day of batch experiment exposure, analysis of leachate wa-
ters for spent shale 1 indicated about 10 mg/1 TOC and 8000 ymhos per cen-
timeter specific conductance. Continuous flow experiments yielded leachate
of 20 to 25 mg/1 TOC and 6000 umhos per centimeter specific conductance
after 10 days (Amy and Thomas, undated). It should be noted that these ex-
periments were conducted using distilled water. Groundwaters of varying
quality may produce different results.
The observed distribution of major organic fractions from batch leaching
experiments using simulated in-situ, combustion retorted spent shale is as
follows (LBL, 1978):
Leached amount (milligrams per 100 grams)
Temperature
Leaching water (°C) Total Acid Base Neutral
Distilled 20 850-2,000 290-680 360-460 200-860
Distilled 80 640-1,290 110-500 240-610 180-290
(continued)
44
-------
Leached amount (milligrams per 100 grains)
Temperature
Leaching water (°C) Total Acid Base Neutral
Synthetic
groundwater 20 1,450 420 370 660
Synthetic 80 1,190 500 330 360
groundwater
The amounts of each fraction leached using the synthetic groundwater was
within the range of observations using distilled water.
An assessment of in-situ leaching processes by Lawrence Berkeley Labs
(LBL, 1978) notes the difficulties of evaluating inorganic leachate quality
due to the great spatial variability in inorganic character of oil shale.
Also, variation in the quality of groundwater can be expected to appreciably
affect the leaching process. Among the water quality constituents important
in this manner are alkalinity (which is related to the potential for carbon-
ate precipitation) and TDS (which may affect ion exchange processes or pro-
duce common ion effects which influence solution processes and equilibria).
Discussion of these phenomena is presented in Section 7, Potential Pollutant
Mobility.
Summaries of experimental data on the concentration of various constitu-
ents in leachate from surface and in-situ retorted shale are shown in Table
3-4. These data show that leachate from in-situ spent shale may be (1) lower
than leachate from surface retorted shale with regard to the concentration of
TDS, fluoride, sulfate, nitrate, magnesium, sodium, potassium, boron, and
molybdenum, and (2) higher than surface retorted shale with regard to the
concentration of carbonate.
These data (Table 3-4) were used by LBL (1978) to group constituents
according to the amount of material potentially leached from in-situ pro-
cessed shale:
1. Less than 10 mg per 100 g: N03, Cl, F, Mg, Al, B, Cr, Fe,
Li, Mo, Pb, Sr, Zn
2. Between 10 and 100 mg per 100 g: HC03, OH, K, Si
3. Greater than 100 mg per 100 g: €03, $04, Ca, Na.
Assuming the adequacy of these estimates, the potential amount leached from
abandoned in-situ retorts can be estimated as follows:
Leachable amount (1Q5 tons)
Amount in-situ
Tract spent shale (tons) Category: 1 2 3
C-a 9.8 - 14.4 x 108 <1.4 0.98 - 14.4 > 9.8
C-b 1.5 x 2.2 x 109 <2.2 1.5 - 22 >15
45
-------
TABLE 3-4. SUMMARY OF LITERATURE ON LEACHATE (USING DISTILLED
WATER) FROM SIMULATED IN-SITU RETORTED SHALE AND
FROM SURFACE RETORTED SHALE (LBL, 1978)
Constituent
Simulated in-situ retorts
Surface retortsa
General water
quality measures
pH
Total dissolved
solids
Major inorganics
Bicarbonate
Carbonate
Hydroxi de
Chloride
F1uor i de
Sulfate
Nitrate (N03)
C al ci urn
Magnesium
Sodium
Potassium
Organics
Total organic
carbon
7.8 - 12.7
80 - >2,100
22 - 40
30 - 215
22 - 40
5.5
1.2 - 4.2
50 - 130
0.2 - 2.6
3.6 - 210
0.002 - 8.0
8.8 - 235
0.76 - 18
0.9 - 38
7.8 - 11.2
970 - 10,011
20 - 38
21
5
3.4
600
5.1
42
3.5
165
10
33
60
6,230
5.6
114
91
2,100
625
Trace elements
Aluminum
Arsenic
Boron
Barium
Chromi urn
Iron
Lead
Lithium
Molybdenum
Selenium
Silica
Strontium
Zinc
0.095 - 2.8
—
0.075 - 0.14
___
0.002 - 1.8
0.0004 - 0.042
0.014 - 0.017
0.020 - 0.42
trace
—
25 - 88
0.004 - 8.7
0.001 - 0.025
___
0.10
2-12
4.0
—
—
—
—
2-8
0.05
___
___
— — —
aTOSCO, U.S. Bureau of Mines, and Union Oil Company processes.
46
-------
Thus, modified in-situ developments, such as proposed on Tracts C-a and C-b,
result in a large potentially Teachable mass.
Estimates of the potentially Teachable quantities of trace inorganics
are listed in Table 3-5. Elements for which estimates of Teachable quantity
are greater than I milligram per 100 grams (or 10~5 tons per ton spent
shale) are boron, cerium, chloride, manganese, rubidium, nickel, vanadium,
barium, and phosphorus.
The data presented above are largely for laboratory and simulated in-
situ experiments. As previously noted, actual leaching processes can be ex-
pected to vary with geographic location, characteristics of retort operation,
and quality of groundwater moving through the retort zone. As one example of
data from a field-scale experiment, data listed in Table 3-6 show the observed
influence of spent in-situ oil shale on groundwater quality. These data,
taken from a Wyoming test site, show very large increases in concentration,
particularly sodium sulfates and bicarbonates. Note that these constituents
are also listed above as having a large potential for leaching from in-situ
spent oil shale.
47
-------
TABLE 3-5. ESTIMATED QUANTITIES OF MATERIAL LEACHED FROM SPENT SHALE
(LBL, 1978)
Element
Ag
As
B
Ba
Be
Bi
Br
Cd
Ce
Cl
Co
Cs
Cu
Dy
Er
Eu
Ga
Gd
Ge
Hf
Hg
Ho
I
La
Lu
Mn
Quantity leached9
(mg/100 g)
<0. 00002-0. 026
<0. 003-1. 3
<0. 012-3. 5
<0.061-11
<0. 0001 8-0. 084
<0. 0001-0. 092
<0. 0003-0. 90
<0. 00002-0. 02 T
<0.04-3.2
<0.028->150
<0. 00078-0: 32
<0. 00006-0. 16
<0. 017-1. 8
<0. 00027-0. 059
<0. 00001-0. 021
<0. 00018-0. 030
<0. 001-0. 27
<0. 00006-0. 27
<0. 00037-0. 044
<0. 0006-0. 060
<0. 0001-0. 032
<0. 00005-0. 007
<0. 0001 -0.44
<0. 0011-0. 75
<0. 00006-0. 0077
<0. 009-5. 7
Element
Mo
Nb
Nd
Ni
P
Pb
Pr
Rb
Sb
Sc
Se
Sm
Sn
Ta
Tb
Te
Th
Ti
Tl
Tm
U
V
W
Y
Yb
Zr
Quantity leached3
(mg/100 g)
<0. 009-1. 3
<0. 001 -0.30
<0. 024-1. 2
<0. 028-11
<0.5->75
<0. 001-1.1
<0. 0006-0. 28
<0. 011-6. 8
<0. 0002-0. 17
<0. 0001 2-1.0
<0. 0008-0. 078
<0. 0005-0. 14
<0. 0004-0. 069
<0. 0004-0. 072
<0. 00013-0. 017
<0. 0003-0. 005
<0. 001 -0.18
<0. 15-47
<0. 0003-0. 021
<0. 00003-0. 003
<0. 0003-0. 12
<0. 010-4. 2
<0. 00003-0. 044
<0. 001 8-0. 75
<0. 00024-0. 038
<0. 003-0. 90
Range corresponds to 1 to 15 percent of content in raw oil shale
as reported in LBL, 1978 (Poulson et al., 1977).
48
-------
TABLE 3-6. WATER QUALITY ANALYSIS OF GROUNDWATER NEAR TRUE IN-SITU OIL SHALE EXPERIMENT
(DATA FROM JACKSON et al., 1975)
10
Concentration (mg/1)a
Constituent
pH
IDS
Bicarbonate (HC03)
Carbonate (C03)
Sulfate (S04)
Nitrate (N03)
Chloride (Cl)
Fluoride (F)
Calcium (Ca)
Magnesium (Mg)
Sodium (Na)
Potassium (K)
Boron (B)
Before
burn
9.7
5,029
1,300
671
254
1.2
931
9.1
11
4.7
1,830
6.9
11
Initial leaching
period
8.6
30,030
9,750
1,940
4,810
4.5
4,250
53
50
230
8,900
34
-
4 years
after burn
9.3
10,721
3,046
1,032
2,400
_
592
25
2.7
6.1
3,460
101
40
| Change from before burn
Observed change
from initial leaching
0.89
5.97
7.50
2.89
18.94
5.40
4.56
5.82
2.54
48.94
4.86
4.93
-
Observed change
over longer term
0.96
2.13
2.34
1.54
9.45
-
0.64
2.75
0.25
1.30
1.89
14.64
3.64
aData are averages for a set of well water samples.
Ratio of observed concentration (or pH level) at indicated time to before-burn concentration.
-------
SECTION 4
GROUNDWATER USE
Beyond use by oil shale developers, there is no extensive use of ground-
water from aquifers beneath Tracts C-a and C-b. This is likely due to
groundwater quality and depth considerations, availability of surface water
sources, and the general limited agricultural, livestock, industrial, and
municipal development in the region.
Approximately 5100 acres of land in the Piceance Creek watershed are
irrigated for hay and pasture!and. Substantial withdrawals are made in the
months of April and May. Approximately 200 acres in the Yellow Creek water-
shed are irrigated using Yellow Creek water.
As will be noted in Sections 5 and 6, the aquifers beneath Tracts C-a and
C-b are believed to discharge near the basin center into the surface drain-
ages of Piceance and Yellow Creeks. These creeks, in turn, discharge to the
White River and subsequently into the Green and Colorado River systems.
Hence, although direct use of groundwaters is limited, groundwater quality
perturbations may influence a variety of municipal and agricultural water
uses downstream in the Colorado River Basin.
50
-------
SECTION 5
HYDROGEOLOGIC FRAMEWORK
In this section, the general climate, physiography, geology, and hydrol-
ogy of the study area are presented, along with site-specific data on Tracts
C-a and C-b.
CLIMATE
The Piceance Basin is characterized by semi arid montane climate. There
is considerable variation between the center of the basin and its high rim.
Summer temperatures in the lower northern areas average near 75°F, while
the western and northern highlands may be 15 degrees cooler. The temperature
differential between the basin highlands and the center in the winter is
less, but even near the White River temperatures can average below freezing.
The majority of the precipitation occurs as winter snowfall. Most of
this snow falls on the highlands. Winter precipitation there can reach 16
inches,, but at low elevations may only be 6 inches. Summer rainfall follows
the same pattern, with only 6 inches at low elevation and up to 10 inches
along the rim.
The high summer temperatures coupled with low humidity create a high
evapotranspiration rate. In the low areas, it far exceeds available precipi-
tation. The longer cool season and large amount of winter snow at high ele-
vations raise the precipitationrevapotranspiration ratio.
PHYSIOGRAPHY
Topography and Setting
The Piceance Basin is set in a wide plateau area between the Colorado
Rockies and the Wasatch Range (Figure 5-1). The entire drainage of this area
is tributary to the Colorado River. The Piceance Basin itself is roughly
circular in shape. It is bounded on the west by the Cathedral Bluffs, to the
top of which the basin slopes gently up from its center. On the south, this
slope flattens into the Roan Plateau, which drops off suddenly at the Roan
Cliffs into Parachute Creek and Roan Creek Valleys. On the east, the Grand
Hogback provides a less dramatic boundary. The White River, into which the
basin drains, is the northern boundary.
51
-------
112°
42° _____
m
= 01 =
— J> —
=c> =
~- "7* ~~
106°
| np___ _WYOMI_NG_ _108° __, —
ARIZONA NEW MEXICO
25
50
I
100 MILES
I
Figure 5-1.
Major structural features in study area (modified from
Cashion, 1967). Locations of Tracts C-a and C-b within
Piceance Basin are shown in Figure 5-3.
52
-------
Undforms
The basin has the rough configuration of a shallow bowl. There are few
topographic irregularities or distinctive features. This sloping bowl shape
has been dissected at regular intervals by streams draining from the high
edges of the basin. Thus, most of the relief is provided by stream erosion.
In the eastern center of the basin, the Dry Fork of Piceance Creek and the
main fork have cut headward toward each other, leaving an isolated highland
between them. The elevation of the basin ranges from nearly 9000 feet around
the western and southern margin to below 6000 feet at the White River.
Drainage Patterns
The Piceance Basin is drained by two streams, Yellow Creek and Piceance
Creek. These both empty into the White River, which flows into the Green
River, a tributary to the Colorado. Both Yellow and Piceance Creeks extend
to a position near the center of the basin before they receive significant
inflow. From this point they are joined at regular intervals by radial, bi-
furcated tributaries. The tributaries flow in nearly straight paths from the
rim of the basin to the main drainage. The tributaries flow in moderately to
deeply incised valleys. This unusually lineal drainage pattern may be attrib-
uted to the incision of initially high-gradient streams on a smooth upland
into very homogeneous sediments. -In a few places the stream pattern may be
observed to follow the predominant northwest-northeast joint set.
REGIONAL STRATIGRAPHY
A generalized geologic section of the Piceance Basin is shown in Figure
5-2.
Wasatch Formation
The Early Eocene Wasatch Formation is composed of fluvial red and gray
shale and siltstone interbedded with massive gray to brown sandstone. The
bedding is generally irregular and discontinuous. The formation is exposed
continuously around the margin of the Piceance Basin. It is thickest on the
eastern side of the basin, over 5500 feet in places, but thins to only a few
hundred feet in some locations on the western side.
Green River Formation
The Green River Formation was deposited on the fluvial sandstones of the
Wasatch Formation. The identifying characteristic of the Green River Forma-
tion is its lacustrine nature. The chemically reduced environment of the an-
cient lake bed created drab white and gray sediments which contrast strongly
with the red and brown tones of the Wasatch Formation. The Green River For-
mation is divided into four lithologic units: the Douglas Creek, Garden
Gulch, Anvil Points, and Parachute Creek Members.
53
-------
on
Wasatch Formation "
3000
024 6 KILOMETRES
VERTICAL EXAGGERATION X 21
DATUM IS MEAN SEA LEVEL
Figure 5-2. Geologic section through the Piceance Basin along north-south line between Tracts C-a
and C-b (Weeks et al., 1974).
-------
Douglas Creek Member--
The Douglas Creek Member dates from the Early to Middle Eocene. This
member is characterized by fine- to medium-grained quartz sandstone, inter-
bedded with shale, siltstone, and limestone. Most of the limestone is ooli-
tic or algal, and some is ostracodal, occurring in thin to massive beds. The
member contains little oil shale. Bedding is even, and laterally continuous.
The Douglas Creek Member intertongues extensively with the underlying
Wasatch Formation. The fluvial Wasatch tongues are commonly difficult to
distinguish from the lacustrine Douglas Creek Member due to the close rela-
tionship of the environments of deposition.
The Douglas Creek Member crops out on the western side of the basin,
where it exceeds 800 feet in thickness. The thickness decreases toward the
east and beneath the center of the basin. The Douglas Creek Member grades
laterally into the sandy facies of the Anvil Points Member.
Garden Gulch Member--
The Garden Gulch Member represents an early playa-lake center environ-
ment. This member is composed of fine-grained sediments, mostly thin or
papery shale, with some marl stone and a few thin sandstone and limestone
beds. The member differs from the overlying Parachute Creek Member primarily
in the smaller amount of oil shale it contains. Near the basin center, the
Garden Gulch Member ranges from 1000 feet near the depositional center to
about 90 feet near the western basin margin.
Anvil Points Member—
The Anvil Points Member is the shore facies on the eastern side of the
basin. Very heterogeneous in composition, it contains a slight preponderance
of gray shale, with a large amount of sandstone (which occurs both thinly
interbedded with the shale and in massive strata), some marlstone, siltstone,
and algal and oolitic limestone. The member conformably overlies the Wasatch
Formation and conformably underlies the Parachute Creek Member of the Green
River Formation, intertongueing with both of these units. The maximum thick-
ness of the member is 1800 feet. This thickness decreases to zero a short
distance from the eastern margin of the basin by gradation into strati graph-
ically equivalent units.
Parachute Creek Member--
The Parachute Creek Member sediments were deposited in the center of a
very large saline playa. The sediments around the center of the basin are
largely marlstone, with some oil shale. The basal deposits in the center of
the depositional basin are mainly evaporites, nahcolite (NaHC03), and daw-
sonite (NaAHOH^COs), and halite (NaCl). Some oil shale is interbedded with
these evaporites, which attain a maximum thickness of over 1000 feet in the
center of the basin. Above the saline zone is a section of very rich oil
shale known as the Mahogany Zone. This zone is present over the entire area
of the basin and is also present in the Uinta Basin of Utah. Above the
55
-------
Mahogany Zone, which ranges from less than 3 to about 100 feet in thickness,
the formation consists of interbedded marl stone and oil shale. The thickness
of the entire member varies from 1800 feet to less than 600 feet.
Uinta Formation
The beds of the Uinta Formation record a return to fluvial conditions.
The Uinta Formation is composed of sandstone, marlstone, siltstone, and
shale. The proportion of sandstone increases toward the top of the forma-
tion. The formation is generally conformable with the underlying Parachute
Creek Member, but is locally unconformable. In places, the contact has been
distorted by plastic flow of the fine-grained Green River sediments beneath
the load of the denser Uinta sandstones.
STRUCTURE
The Piceance Basin is asymmetric in shape, steepest on the north and
east sides, and gently sloping on the south and west. The dip at the nor-
thern end of the basin ranges between 15 and 30 degrees, while on the south
it is less than 1 degree in places. The Douglas Creek Arch separates the
Piceance Basin from the Uinta Basin to the west. The Uncompahgre Uplift
bounds the basin to the south and the Grand Hogback to the east. The basin
terminates on the north in the complex system of major anticlines (including
the Rangely and Blue Mountain Anticlines) tributary to the Uinta Mountain up-
lift. The gross structure of the basin has experienced only minor distortion
from local deformation. Northeast-southwest stresses have created a series
of northwest trending anticlines. These features are gentle (Figure 5-2) and
in harmony with the general trend of the basin.
Several small faults have been mapped in the center of the basin, between
Federal Prototype Lease Tracts C-a and C-b. These faults trend northwest and
southeast, and generally show less than 50 feet of displacement. Several of
them are double faults with a small graben between.
GENERAL BASIN HYDROGEOLOGY
The area contains three important aquifer systems: the Lower Aquifer,
the Upper Aquifer, and the alluvial aquifers. The Lower Aquifer occurs in
the Parachute Creek Member below the Mahogany Zone and the Upper Aquifer is
above the Mahogany Zone. The alluvial aquifer system occurs in the stream
valley bottoms.
Lower Aquifer
The Lower Aquifer is bounded generally on the top by the Mahogany Zone
and on the bottom by the shales of the Garden Gulch Member. Porosity is
mostly secondary, resulting from fracturing and jointing of the marlstone and
oil shale of the lower Parachute Creek Member. Porosity also results from
the solution of the evaporite minerals in the saline section at the base of
the Parachute Creek Member. Removal of these soluble minerals by groundwater
has created a zone of high permeability at the top of the saline section
known as the leached zone. The saline section below the leached zone still
56
-------
contains its original salts. Because of the high electrical resistivity of
the salts which characterizes this zone on geophysical logs, it is called the
"high resistivity" or "HR" zone. Inasmuch as both the high kerogen content
oil shales and the saline minerals of the high resistivity zone are rather
ductile, the HR zone has experienced little fracturing and has a low permea-
bility. Because of these characteristics, in the center of the basin the
high resistivity zone forms the lower confining stratum.
The fracture-solution nature of this confined aquifer results in hetero-
geneous hydraulic characteristics. Figure 5-3 shows transmissivity (T) values
computed by Weeks et al. (1974) for specific aquifer tests on the Lower Aqui-
fer. The values range from 8 to 1940 ft2 per day. In general, transmis-
sivity increases with the soluble mineral content from the margins to the
center of the basin. The degree of fracturing, resulting from deformation,
increases toward the structural axis of the basin, and northwest along the
axis. Weeks et al. (1974) estimated that the average transmissivity varies
from 130 ft2 per day near the southeastern corner of the basin, to 670 ft2
per day in the area between Yellow and Piceance Creeks. They estimated the
storage coefficient to be on the order of 10"^ and the specific yield to be
10"1. Well yields of 200 to 400 gallons per minute are typical.
Upper Aquifer
The Upper Aquifer is separated from the Lower Aquifer by the Mahogany
Zone. Although no interaquifer response was observed during vertical permea-
bility tests, Weeks et al. (1974) have concluded that considerable movement
of water between the aquifers does occur. They base this conclusion on the
fact that the water level in the two aquifers rarely differs by more than 100
feet over the 1200-foot head drop of the two aquifers across the basin.
The Upper Aquifer zone is comprised of the Parachute Creek Member above
the Mahogany Zone and the Uinta Formation. The lower portion of the Uinta
Formation is divided by numerous tongues of the Green River Formation. Al-
though the primary porosity of the sandstones is greater than that of the
marl stones, the sandstone porosity has been decreased by precipitates from
groundwater, while fracturing has increased the permeability of the marl-
stones, which are more susceptible to fracturing than the Uinta sandstones.
The sandstones, therefore, tend to form confining layers for the marl stone
aquifers. The Upper Aquifer is generally confined, but is unconfined in many
locations, depending on the relationship of the water level and the lithology.
Strata containing nahcolite solution cavities which occur in the southern
part of the basin should form transmissive layers.
The transmissivity varies with saturated thickness, degree of fractur-
ing, degree of solution, and location of wells with regard to fractures.
Calculated T values shown in Figure 5-4 range from 8 to 1000 ft' per day.
As both the saturated thickness and the degree of solution increase toward
the basin center, the transmissivity does also. Weeks et al. (1974) consid-
ered representative values'to be 70 ft2 per day around the rim, 130 ft2
per day in the area around the center, and 270 ft2 per day in the center.
57
-------
EXPLANATION
WELL - Number shows transmissivity,
in feet squared per day
108°
./
\
f
/
V '• \
' • "'
/
rf •'
ffS
<&" i
/ 66°.
:'i9o
*j 1670.X
-VT—
_410
i \
Mfiflker -J .
~^\
! J
-.-•
'-4.^,,^^\
. '••
y loo,^1 •
'" CTRACTC-a
*«>
J^K
40
400 ,
X »v' ^> / 7* --
**' X • 3*X '• / .,- TRACT C-b
V -/' / ^7 / 6 / / ^-^=^
V / Q*i
90 ,
90
O'
^ /
/I&40
,
/
110*
, l-. 1
\
\~\
Cr_ / \
Hasp from U. S. Geological Survey
State base map, 1969
0
10
I
15 MILES
10 15 KILOMETRES
Figure 5-3. Distribution of transmissivity in the Lower Aquifer,
Piceance Basin (Weeks et al., 1974).
58
-------
.40
EXPLANATION
WELL - Number shows transmissivity,
in feet squared per day
108°
/./
/
C -"' r ' _^/! / • & '£' w\
•—••-. / / ) f / 1 _ ''>••..'
.^••'/'
Base from US.Geological Survey "*^_ /
State base map, 1969 >Ns*
0 5
I i i i i I
^,
-.-j
10
i
15 MILES
I
10 15 KILOMETRES
Figure 5-4. Distribution of transmissivity in the Upper Aquifer,
Piceance Basin (Weeks et al., 1974).
59
-------
Porosity ranges from 10 percent to 1 percent. It is highest in the cen-
ter, where solution cavities are present, and least around the edges. The
calculated storage coefficient is on the order of 10 , indicating at those
locations confined conditions with nearby unconfined conditions. The total
storage is probably somewhat less than that in the Lower Aquifer due to less
saturated thickness and less porosity.
Figure 5-5 shows the potentiometric level of wells open to both the Upper
and Lower Aquifers. Inasmuch as the difference in water level between the
two aquifers is rarely more than 100 feet, the potentiometric map of either
the Upper or Lower Aquifer should not differ greatly. The potentiometric
configuration is determined by the transmissivity distribution and the re-
charge and discharge characteristics. Recharge occurs around the rim of the
basin. Probably the major source is gradual infiltration of snowmelt in the
spring. The downward potential difference between the two aquifers around
the rim of the basin indicates that most of the recharge is to the Upper
Aquifer and that the Lower Aquifer is recharged by leakage from the Upper
Aquifer through the Mahogany Zone. The water migrates toward the center of
the basin, where, in certain locations, it discharges to Piceance and Yellow
Creeks. Here, the head of the Lower Aquifer is higher than the Upper, and
Lower Aquifer discharge is through the Upper Aquifer.
Alluvial Aquifers
Alluvial sediments line most of the major stream valleys and are usually
saturated at their base. This alluvium is thickest along Piceance and Yellow
Creeks; near the confluence with the White River there may be over 100 feet
of saturated alluvium below Piceance Creek. All of these aquifers follow the
shape of their stream valleys. They are recharged in their upper reaches
from streams and from snowmelt. In the lower sections, they are recharged
from the deep aquifers and, in turn, discharge to the streams, maintaining
the base flow.
The hydraulic conductivity of such unconsolidated alluvial deposits is
high and this high conductivity is reflected in transmissivities of 2700 to
20,000 ft^ per day. The unconsolidated nature also results in high speci-
fic yields, on the order of 20 percent. In spite of these favorable aquifer
parameters, the alluvial aquifers are not desirable areas for large-scale
water development because of the small total storage and boundary effects
created by the aquifer morphology. In addition, withdrawal from the aquifers
is sure to adversely affect the stream base flow and thus agricultural inter-
ests, wildlife habitat, and existing water rights allocations.
HYDROGEOLOGY OF TRACT C-a
General Setting
The following summary is taken largely from Tract C-a environmental
baseline studies (RBOSP, 1977b). Tract C-a is in the western Piceance Basin,
near the headwaters of Yellow Creek. The tract is at the head of the main
valley of Corral Gulch, one of the two large tributaries of Yellow Creek,
where the broad valley divides into several narrow valleys which have cut
60
-------
EXPLANATION
• OBSERVATION WELL - D, indicates downward
and U, indicates upward flow in well
-6200 POTENTIOMETRIC CONTOUR - Shows altitude of
water levels. Contour interval 200 feet (61 metres).
Datum is mean sea level
108°
Meeker_J_
j?*\
^J° \
("" TRACT C-a /
! £*.'' RV \\^^~T
Base from US.Geological Survey
State base map, 1969
0
10
•
MILES
10 15 KILOMETRES
Figure 5-5.
Potentiometric map based on water levels in wells open
to the Upper and Lower Aquifers, April 1974, Piceance
Basin (Weeks et a!., 1974).
upwards toward the Cathedral Bluff ridge. The tributaries of Corral Gulch,
which flow east across the tract, unite at the east boundary. The flow of
the main fork of Corral Gulch, up to the confluence with the Dry Fork, is
broad and flat, but the rest of the canyons are V-shaped, with steep walls
separated from adjacent canyons by rounded ridgetops. The elevation ranges
from 6600 feet in Corral Gulch to 7400 feet on the western boundary.
61
-------
Surficial outcrops within the tract boundaries belong to the Uinta For-
mation and intruding tongues of the Green River Formation. The main body of
the Green River Formation is not exposed on the tract, but the Black Sulfur
Tongue and another unnamed tongue are present. Figure 5-6, an east-west
cross section of Tract C-a, shows the relative position of these features.
Structure
The major structural feature beneath Tract C-a, the Sulfur Creek Anti-
cline, crosses the southwest corner of the tract, plunging southeast (Figure
5-7). Associated with the anticline are a series of parallel faults, in
echelon from northwest to southeast. The largest and most complex of the
fault groups cuts across the north part of the western tract boundary. This
fault group, like most of the others, has two parallel faults with a down-
dropped graben between them as its major features. The maximum displacement
along this graben is 230 to 240 feet. Such grabens are apparently a result
of tensional forces along the nose of the anticline.
Also associated with the structural deformation is the jointing and
fracturing of the rocks. The major joint set is nearly vertical and oriented
N50°-76°W, approximately parallel to the strike of the anticline. A secondary
set strikes N28W, and a tertiary set N15W.
Precipitation and Drainage
The average annual precipitation over the tract is about 12 inches.
Precipitation increases to the west with elevation. Table 5-1 compares pre-
cipitation at Yellow Creek, Tract C-a, and the Cathedral Bluffs to the west.
Because of this fairly low precipitation, only those drainages with head-
waters extending to the west of the tract flow consistently. Corral Gulch is
the only water course with perennial flow, although Box Elder Gulch is fairly
dependable in the spring. Figure 5-8 indicates most of the streamflow is de-
rived from springtime snowmelt. Ths total annual discharges of the tract
watersheds are listed in Table 5-2.
Springs and Seeps
Numerous springs and seeps have been found near Tract C-a, six within or
near the tract boundaries. The source of the flow for the six springs marked
in Figure 5-9 was identified by means of a comparison of spring elevation
with the potentiometric of the Upper Aquifer (Method 1), a statistical analy-
sis of spring flow (Method 2), and comparison of flow between different
springs (Method 3) (Table 5-3).
Alluvial Aquifers
Some of the springs which supply flow in the perennial water courses are
undoubtedly fed by the alluvial aquifers. Seven holes were drilled in allu-
vium on and near the tract in. order to investigate these alluvial aquifers.
Water was encountered in only four of the holes, along the main fork of Corral
Gulch and Box Elder Gulch and Stake Springs Draw. The thickness of saturated
alluvium ranged from 12 to 54 feet, averaging 27 feet. The locations of these
62
-------
SWEST
t^
CO
O
7200 T
7000
N EAST
GENERAL
LOCATION:'
UPPER AQUIFER
6800
6600
en
to
en
I
LOWER AQUIFER
O
uu
5400
•z.
oc
O
LL
I*
L8
R-8
A-GROOVE
MAHOGANY ZONE
B-GROOVE
R-6
L-5
HORIZONTAL SCALE
VERTICAL EXAGGERATION 5:1
Figure 5-6. East-west geologic section through Tract C-a.
-------
\
o
\ "'"i1
\\ A \ -,\, \
fe IK / OS-,4 V>x
• DRILL HOLE
+ CONVENTIONAL WELL
«•» OBSERVED SURFACE FAULT DISPLACEMENT
"*• PROJECTED FAULT
Kllom«t«r
Figure 5-7. Tract C-a middle A-groove structure map (RBOSP, 1977a).
TABLE 5-1. PRECIPITATION SUMMARY, WATER YEARS 1975 AND 1976
Location
Cathedra.1 Bluffs
Tract C-aa
Yellow Creek
Monthly
maximum
2.87
2.10
1.67
1975
Monthly
minimum
0.43
0.16
0.04
Total
16.30
13.25
10.85
Monthly
maximum
2.49
1.97
1.91
1976
Monthly
mi nimum
0.40
0.12
0.29
Total
17.25
11.83
10.72
a!975 values are from Stakes Springs Draw data; 1976 values represent the
averages of Dry Fork, Corral Gulch, Box Elder Gulch, and Stake Springs Draw
data.
64
-------
er»
tn
1 1 1 1 1 I
—
—
r
pi
1111111
1 1
wm^^i^—
1 1 1 1 1 1 1 1 1 1 1
• —
BBBSI_
o
LU
cc
V)
I 1
0
1
0
BOX ELDER GULCH NEAR WEST LINE TRACT C-a
1
— r^---.^--a___i.-----
CORRAL GULCH NEAR
—
— ± i -
WEST LINE TRACT C-a
—
DRY FORK NEAR WEST LINE TRACT C-a
CORRAL GULCH NEAR EAST LINE TRACT C-a
RINKY DINK GULCH TRACT C-a
NO FLOW
STAKE SPRINGS DRAW NEAR CORRAL GULCH
N D J F M A M
WATER YEAR 1975
JUASONDJ
YELLOW CREEK NEAR WHITE RIVER
FMA'MJ JA S
WATER YEAR 1976
Figure 5-8. Monthly mean flows at seven gaging stations, water years 1975 and 1976 (RBOSP, 1977b)
-------
TABLE 5-2. ANNUAL RUNOFF (acre-feet).
Station
Water year
1974a
Water year
1975
Water year
1976
Dry Fork near west
line, Tract C-a 1.4 0.2 4.3
Corral Gulch near
west line, Tract C-a 134.0 96.7 98.5
Box Elder Gulch near
west line, Tract C-a 148.4 182.8 34.8
Rinky Dink Gulch near
east line, Tract C-a no data 0.6 2.3
Corral Gulch near east
line, Tract C-a 309.3 626.2 418.1
Stake Springs Draw
near confluence with
Corral Gulch 0 0 15.5
Yellow Creek near
White River l,740b 1,158.7 1,103.1
aMarch through September only.
^Complete records for water year 1974.
R. IOOW.
R.99W.
R.98W.
SCALE
* PERENNIAL SPRINGS 8 SEEPS
A OTHER SPRIN6S a SEEPS
Figure 5-9.
Springs and seeps in vicinity
of Tract C-a (RBOSP, 1977b).
66
-------
TABLE 5-3. SUGGESTED SOURCE OF SPRING WATER
Station
1
2
Method 1
Alluvial
Upper Aquifer
Method 2
Alluvial
Alluvial
Method 3
Alluvial
Alluvial and
3
4
5
8
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
Upper Aquifer
holes are identified in Figure 5-10 and the data for them summarized in Table
5-4. That these alluvial aquifers are indeed closely related to the surface
water of the region is.strongly indicated by the comparison of aquifer water
level and streamflow in'Figure 5-11. The springtime rise in alluvial aquifer
water levels is a response to infiltration of snowmelt.
Deep Aquifers
The configuration of the Upper and Lower Aquifers beneath Tract C-a is
shown in Figures 5-12 and 5-13 (RBOSP, 1977b). The positions of the aquifers
shown were located by means of open hole well flow charts which were con-
structed using spinner logs. These data indicate that, to a considerable ex-
tent, the aquifers are completely independent of lithology and stratigraphy.
Aquifer tests on the Tract C-a wells established that the vertical permeabil-
ity of the upper Mahogany Zone is exceedingly small (15 x 10~7 ft per day).
Weeks et al. (1974) reported that in none of the many aquifer tests performed
over the basin were they able to observe influence of pumping across the Ma-
hogany Zone. Thus, to show the entire thickness of the Upper Aquifer varying
from above the top of the Mahogany Zone to well below it seems unrealistic.
Spinner logs only respond to flow between layers of different head within
a well. If the head difference is not significant, no flow will occur between
even highly transmissive layers. Thus, Figures 5-12 and 5-13 probably more
accurately reflect relative head differences within the aquifers than they do
the locations of the most transmissive zones within the aquifers. Inasmuch
as the well perforations were placed on the basis of this analysis, the wells
may also not be representative of the aquifers, as defined on the basis of
either transmissivity or water quality. The cross-sectional configuration of
the aquifer is shown in Figure 5-6, with aquifer divisions indicated on the
basis of stratigraphy rather than flow logs.
Upper Aquifer—
The potentiometric surface of the Upper Aquifer (RBOSP, 1977b) under
Tract C-a shows an orientation fairly well in accordance with the regional
67
-------
R99W
R 98 W
CO
SHALLOW MONITOR HOLES
DEEP MONITOR HOLES
Figure 5-10. Tract C-a monitoring holes (RBOSP, 1976).
-------
TABLE 5-4. SUMMARY OF ALLUVIAL MONITORING HOLES PHYSICAL DATA
Hole
G-S S-7
6-S S-8
G-S S-ll
G-S S-12
Depth
(feet)
44
50
66
87
Mean static
water level
(feet)
21. 6a
35. 7a
44.0
32.6
Standard
deviation
2.5
3.7
1.5
1.5
. Mean
temperature
(°F)
48.6
49.2
50.6
49.7
Standard
deviation
2.9
2.9
3.0
5.3
Mean
Conductivity
(ymhos)
1,096
970
1,796
1,596
Standard
deviation3
58.0
83.3
187.5
135.9
Geometric mean, standard deviation by method of movements.
-------
ALLUVIAL HOLE S-8
BOX ELDER GULCH NEAR WEST LINE TRACT C-a
o
ALLUVIAL HOLES-7
LU
cc
LLI
O
28
24
20
16
2
1
- START
- DATA "
ALLUVIAL HOLE S-11
CC
LU
I
CORRAL GULCH NEAR WEST LINE TRACT C-a
O N
M
M
M
AMJJASONDJF
CORRAL GULCH NEAR EAST LINE TRACT C-a
WATER YEAR 1975 WATER YEAR 1976
Figure 5-11. Alluvial hole water level versus stream-flow (RBOSP, 1977b).
-------
7400 i—-
G-S 11
G-S12
7000 —
G-S 13
BOX ELDER GULCH
CE 705A
A-GROOVE
B-GROOVE
BLUE MARKER
ORANGE MARKER
4600
Figure 5-12. Cross section, Upper and Lower bedrock aquifer under Tract C-a (RBOSP, 1977b)
-------
ro
7400
7000
6600
LU
>
Ul
6200
O
m
<
z
° 5800
LU
_l
111
5400
5000
4600
G-S1
CE.707 CORRAL GULCH Q-S 9
I
, CE 708
G-S13
GULCH
G-S14
G-S15
^—• ^-^ A-GROOVE
^^ —— B-GROOVE
— —--- BLUE MARKER
^— --^— ORANGE MARKET
Figure 5-13. Upper and Lower bedrock aquifers under Tract C-a (RBOSP, 1977b)
-------
model presented in Weeks et al. (1974), although the gradient is somewhat
steeper across the tract. The Weeks model shows the 7000-foot head line sev-
eral miles farther west than does Figure 5-14. The gradient in Figure 5-14
is about 130 feet per mile. The potentiometric map shows little evidence of
either recharge or discharge in the vicinity of the tract.
Upper Aquifer hydraulic parameters were determined through a large num-
ber of short (informal) aquifer tests and one long (formal) test (RBOSP,
1977b). The average transmissivity reported was 2040 ft* per day and the
average storage coefficient was 6.8 x 10'5. This transmissivity is high in
comparison to the values reported by Weeks et al., which were on the order of
perhaps 130 to 270 ft2 per day. It appears that the high T values obtained
may be the result of pumping only long enough to reach the relatively flat
middle limb of the typical semi-log fractured aquifer drawdown curve. For
this report, drawdown and recovery curves were not obtained or available for
all of the tests on Tract C-a, and those which were obtained did not contain
information necessary for complete analysis. Several shortcomings were noted.
Tests tended to be too short, measurements during recovery were not carried
out for a long enough period, and incorrect recovery measurements were used.
Without more information, no definitive model of the aquifer characteristics
can be constructed.
Area-wide water-level change data were used to overcome aquifer test
inadequacies. Eleven wells on the tract were open to both aquifers for two
years after drilling. An estimated 50 gallons per minute flowed from the
Upper to the Lower Aquifer. After 2 years, the aquifer interconnection was
cut off and water levels in the Upper Aquifer began to recover. A Theis-type
interference model was constructed to simulate recovery data. Calibration of
the model showed that the use of a transmissivity of 400 ft2 per day and a
storage coefficient of 10~3 best produced the recovery data.
Upper Aquifer test drawdown cones for wells G-S 12 and CE 705A are il-
lustrated in Figures 5-15 and 5-16, respectively. The influence of faulting
on the Upper Aquifer is clear. The potentiometric surface map of Figure 5-14
is reconstructed in Figure 5-17 to show the influence of faults as no-flow
boundaries.
The elliptical shape of the drawdown cone in Figure 5-16 indicates a
strongly anisotropic aquifer. Utilizing the principle that Tmax = (a/b)Te
(where a equals the major axis of the drawdown ellipse, b equals the minor
axis, and Te is the effective transmissivity), and Tm-jp = (b/a)Te, Tmax
equals 2.9 Te, and Tmin equals 0.35 Te. If Te is 400 fV per day, Tma<
is 1160 ft2 per day and Tmin is 140 ft2 per day. The ratio Tmax:Tm-jn is
8.3:1. Tmax is oriented N23W, slightly east of what would be expected from
the joint and fracture orientations given.
Such major anisotropy should cause a significant divergence of the flow
pattern from what would be expected if the aquifer were isotropic. Figure
5-18 is an anisotropic flow net of the Upper Aquifer below Tract C-a, con-
structed by means of an anisotropic flow net transform. This flow net does
not attempt to include the effects of the faults individually, as presented
in Figure 5-17, but is based on Figure 5-14, an "averaged" approximation of
73
-------
.GSM-1
TRACT OUTLINE
DRILL HOLES
»CONTOUR INTERVAL SOFT
I Milt
.5 I Kilometer
691318
TJS.
T.2S.
I Mil*
Kilometer
— TRACT OUTLINE
• DRILL HOLES
—•» CONTOUR INTERVALS 5 FEET
Figure 5-14. Upper Aquifer piezometric levels
(feet), Tract C-a, November 1975
(RBOSP, 1976).
Figure 5-15. Upper Aquifer test drawdown G-S 12
at approximately 13,000 minutes after
test start, Tract C-a (RBOSP, 1977b).
-------
.GSM-I
.GSM-I
R.99W.
6S-DI8
ris.
T.2S.
R.99W.
LEGEND
— TRACT OUTLINE
• DRILL HOLES
—— CONTOUR INTERVAL 5 FEET
,5
I MIX
i Kllom«ter
R.99W.
LEGEND
FAULTS
• EQUl- POTENTIAL LINES
I Mil*
,5 I Kllomater
Figure 5-16. Upper Aquifer test cone of depression, Figure 5-17.
Tract C-a (RBOSP, 1977b).
Potentiometric surface for Upper
Aquifer reconstructed from Figure
5-14 to show influence of faults
on Tract C-a (RBOSP 1977b).
-------
LEGEND
—.TRACT OUTLINE
• DRILL HOLES
-——» CONTOUR INTERVAL 50 FT
+ FLOW DIRECTION
! Mile
I Kilometer
Figure 5-18. Anisotropic flow net for Upper Aquifer on Tract C-a
(RBOSP, 19775).
the actual surface. Figure 5-18 is, therefore, not exact and should be taken
to represent only a generalized simplification of the actual flow. Any er-
rors in the original map are exaggerated during the transformation process.
In particular, the source of flow is probably not concentrated in the north-
west corner of the tract, but is more evenly distributed along the western
boundary.
76
-------
Lower Aquifer--
The map of the potentiometric surface of the Lower Aquifer is shown in
Figure 5-19. The small contour interval of this map is somewhat misleading.
It is unlikely that the local flow is almost directly opposite the regional
gradient, as the contours near the bottom of the tract would indicate. The
gradients depicted on the southeast section of the map are on the order of 10
feet per mile or even less. These differences may well be as much the result
of different intervals of perforation as of areal changes of head. If the
,66)4
6614
LEGEND
—— TRACT OUTLINE
• DRILL HOLES
-—--*. CONTOUfc INTERVAL 3 FEET
I Kilometer
Figure 5-19. Lower Aquifer piezometric levels (feet), Tract C-a,
November 20, 1975 (RBOSP, 1977b).
77
-------
smaller anomalies are overlooked, the Lower Aquifer map shows several signif-
icant differences from the Upper Aquifer map. The much flatter gradient in
the Lower Aquifer (10 feet per mile across the tract compared to 130 feet per
mile) is striking. This difference is probably at least partly a result of
the much higher transmissivity of the Lower Aquifer. Another major influence
is the fact that the Upper Aquifer discharges directly into Yellow and Pi-
ceance Creeks, while the Lower Aquifer must discharge by upward leakage to
the Upper Aquifer. This slow, diffuse discharge over a large area should
result in a region near the center of the basin over which the gradient is
nearly flat. The middle of Tract C-a appears to be the border of this dis-
charge area.
Lower Aquifer hydraulic parameters were determined by several short-term
pumping tests and one long-term (length not stated) test. Transmissivity
values ranged up to 2270 ft2 per day for the short-term tests and averaged
1280 ft2 oer day (RBOSP, 1977b). An average storage coefficient value of
2.0 x 10"^ was calculated. The drawdown cone from the long-term test at
well G-S D15 is illustrated in Figure 5-20. The test was of sufficient dura-
tion to affect all the Lower Aquifer wells on the tract. The transmissivity
calculated from this test was 870 ft2 per day and a storage coefficient of
1.2 x 10~4 Was found. It was concluded that 930 ft2 per day was a repre-
sentative transmissivity (RBOSP, 1977b). RBOSP considered this transmissivity
value to be much more dependable than the Upper Aquifer estimate due to the
larger area of the aquifer sampled during pumping. However, the problems
mentioned in the Upper Aquifer testing program evaluation also apply here.
The drawdown cone from the Lower Aquifer test of well G-S D16 is clearly
anisotropic, although not as markedly as that from the Upper Aquifer well CE
705A test. Analysis of the drawdown cone indicates that Tmax equals 1.45
Te and Tm-jn equals 0.17 Te, these values being, respectively, 1350 ft2
per day and 640 ft2 per day if Te equals 930 ft2 per day. The ratio
of Tmax to Tm-jn is 2 to 1. Tmax is oriented N11W.
No evidence of leakage between the Upper and Lower Aquifers was found,
with the exception of the CE 705A Upper Aquifer test. Here, a vertical per-
meability of 3.3 feet per day was derived. The Lower Aquifer pumping tests
at wells G-S D18 and G-S D19 caused a significant response in the Upper Aqui-
fer at the northeast corner of the tract. This interconnection may result
from one or more of three causes: (1) faulty sealing of wells penetrating
both aquifers, (2) fractures created by artificial fracturing experiments
carried out in this area by the Water Resources Division of the U.S. Geologi-
cal Survey (USGS) in 1973, and (3) faults with a high vertical permeability
along the fault (RBOSP, 1977b).
HYDROGEOLOGY OF TRACT C-b
General Setting
Oil Shale Lease Tract C-b is in the southeastern portion of the Piceance
Basin, just south of Piceance Creek. The tract is on the upland above the
Piceance Creek Valley. The tract surface slopes gently upward to the south
and is dissected by several narrow, straight stream valleys and gulches. The
78
-------
>M-I
«0
LEGEND
^^^MIH^Hrt
MM TRACT OUTLINE
• DRILL HOLE
—^ CONTOUR INTERVAL 2 FEET
I Milt
I Kilomtttr
Figure 5-20. Lower Aquifer test cone of depression (RBOSP, 1977b).
chief of these, Willow Creek and Stewart Gulch, bound the tract on the west
and east, respectively. The canyon walls are steep but not rugged and the
intervening ridges are broad and rounded. The elevation ranges from 6400
feet in Stewart and Willow Gulches, to 7100 feet at the south boundary.
All of the rock cropping out on the tract belongs to the Uinta Forma-
tion. The Uinta Formation in the Piceance Basin contains numerous tongues of
the Green River Formation. As the ancient Green River Lake regressed toward
the south in the mid-Eocene, floodplain sands and muds advanced to cover the
lake sediments. However, repeated short-lived transgressions of the lake
79
-------
deposited clays and marls far to the north of the usual lake shore. These
deposits have become thin marl stone tongues within the sandstone and mudstone
of the Uinta Formation. Two of these, the Thirteen Mile Creek and the Black
Sulfur Tongues, are illustrated in Figure 5-21, a north-south cross section
of Tract C-b. The Black Sulfur Tongue crops out on the walls of Piceance
Creek to the north of Tract C-b and the Thirteen Mile Creek tongue crops out
several miles north of Piceance Creek. This tongue merges in the subsurface
with the main body of the Green River Formation just to the south of Tract
C-b.
Structure
The northern portion of the tract is underlain by the axis of a west
plunging syncline. The curvature of the syncline is open and gentle and the
plunge is less than 100 feet per mile. The depth of the Mahogany Zone depends
more upon surface topography than structure. The depth varies from 1000 to
1300 feet (Figure 5-21). No faults or dikes were mapped on the tracts.
Precipitation and Drainage
The average precipitation over the tract is 12.4 inches per year. Pre-
cipitation does not vary greatly from place to place because the elevation
differences are small. Most of the runoff passing over the tract does not
originate from local precipitation, but from snowmelt and rainfall on the
higher Roan Plateau to the south. The only canyons with dependable flow are
Stewart and Willow Gulches, both of which have an annual average flow of about
2 cubic feet per second (1450 acre-feet per year). The discharge of Stewart
Gulch is more constant than that of Willow Gulch.
Discharge of tract streams and Piceance Creek was observed to decline
during the baseline study period (C-b Shale Oil Venture, 1977b). However,
this decline seems to be a return to normal flows after a sudden peak in 1973
(Figure 5-22). One suggested explanation is that this peak was due to the
Rio Blanco project nuclear explosion on May 17, 1973 (C-b Shale Oil Venture,
1977b). In an unsuccessful attempt to stimulate natural gas production in
the tight Fort Union and Mesa Verde Formations, three nuclear explosions with
a combined explosive force of 90,000 tons of TNT were detonated. Some for-
merly dry springs in the area were observed to renew flow. One and one-half
hours after the similar Rulison project blast near Grand Valley, Colorado,
the flow in nearby Battlement Creek tripled. A double mass curve analysis of
White River above and below Piceance Creek (Figure 5-23) indicates that wea-
ther or climatic factors are not responsible. Thus, the peak in Piceance
Creek flow and subsequent decline may well be related to the Rio Blanco
explosion.
Springs and Seeps
No springs or seeps were found within the tract boundaries, but nine
were found within less than 2 miles from the tract boundaries (Figure 5-24).
Most of these were small, intermittent seeps, but several had discharges of 1
cubic foot per second or more. The discharges of most of the gaged springs
(Figure 5-25) are quite constant, with the exception of spring S-10, which
80
-------
7200 I—
7000 —
SOUTH
CO
4600
UPPER AQUIFER
POTENTIOMETRIC LEVEL g
LOWER AQUIFER >
POTENTIOMETRIC LEVEL -n
O
ID
BLACK SULFUR TONGUE
THIRTEEN MILE
CREEK TONGUE
O
FOUR SENATORS ZONE
MAHOGANY ZONE
COMMERCIAL RETORT ZONE
ggiS^SwSSSSS:;: R 6 ZONE
L-5 ZONE
UPPER HALF R-5ZONE
R-5 ZONE
o
ZJ
m
m
23
i\
o
DISTANCE (miles)
Figure 5-21. North-south geologic cross section of Tract C-b (C-b Shale Oil Venture, 1977b),
-------
OD
ro
3
en fj
Q} t
U
c
1
0
44
0 40
' AVERAGE BYSE,
l-day)
N> CO 00
09 NJ O>
I £ 24
1- TJ
0 °
2 | 20
16
12
8
4
MEEKER
—
-
m
PICEANCE CREEK ABOVE
E = ESTIMATED
WINTER - OCT. FEB
SPRING - MAR- MAY
SUMMER- JUN - AUG
— FALL - SEP
—
-
^—
rv
FT"
- "i I*
1
—
WSSF WSSF WS
—
RYAN
i
=
—
—
E r-.
^-m
a
'if
GULCH
5 MONTHS
3 MONTHS
3 MONTHS
1 MONTH
S
F
1965 1966 1967
!3
--
— -
— 1
--
--
d
11
NUCLEAR
DETONATION
MAY 17, 1973
^4
MONTHLY AVERAGE
FOR GIVEN YEAR
_Z ,
~
TT
^C
J
r
WSSF WSSF WSSF WSSF WS
S
F
1968 1969 1970 1971 1972
TT
*-«•"
,
fH
_
i
n
— -,
—
WSSF WSSF
1973 1974
—
— —
-~
—
n
—
1 1 1
—
*
-
-
-
—
WSSF
1975
YEARS
Figure 5-22. Monthly averages by season for streamflow at Piceance Creek above Ryan Gulch, USGS
09306200, and for precipitation at Meeker, 1965-1975 (C-b Shale Oil Venture, 1977b)
-------
1975
1974
i—i—i—i—i—i—i—i—i—i i i i r
IOOO 2000 3000 4000 50OO 6OOO 7OOO
ACCUMULATED AVERAGE WHITE RIVER BELOW MEEKER AND WHITE
RIVER NEAR MEEKER, MONTHLY MEAN DISCHARGE (CFS)
Figure 5-23.
Double-mass curve for White River near Meeker
and below Meeker and Piceance Creek below Ryan
Gulch (C-b Shale Oil Venture, 1977b).
83
-------
Ul
UJ
c»
f 1 \
S-6® 1
r
, SPRING AT WILLOW CREEK R-97W.
[AT MOUTH OF SCANDARO GULCH
*(
5
fi
-L
1 «
VSG-IA
*^SG**I
A~3 A>.
/I V
SPRING AT WILLOW\
CREEK , 3/4 MILE SOUTHX
OF SCAND/
S-S^
T3S. T
*/
Ij
iRD GULCH
II
SG-9
* ••
/•f
(5)S 10
1
/ 5
J
•CB-I /
1
1
^ /
\*o IP
T /
j
\
'v.
^ SG-IOA%
•
\ ''•"-?*
' \
SPRING ON WILLOW CREEK \
2 MILES SOUTH OF '. \
SCANDARD GULCH / j
i CR^ur
: SG-ZIc/
/ /
/ / R97W.
V
1 SP
OF
R.96W. {
/
/ 6 CB-2
i
i
/
^
/( *SG-6 ^/
j AT-ld V
: \ AT-I /
ATHal«5»AT-lb j
j Al~lfl .-
£/ SG~"
SG-io 5y
iS*
?
i
:/*
A A- 13
|
j
1
i
R.96W. ^5
S-3
RING AT MOUTH © ^Lalttr AT MO11TH
STEWART GULCH ® SPRING AT MOUTH
STEWART GULCH ofr STgwART 6U|_CH
<> }
f A-84{
A * }
8 { \ .CB-3 V
/ ! \
7 / T~
• ;
/ •
^
vjv
v-
i ^ '* SG— S\
/ SPRING AT SAVAGE A-9^|
: CABIN, STEWART GULCH*jjS-2
/ SEEP AT MOUTH OF ,®A
• EAST STEWART GULCH ^4
1 (
* *.
/ /
: v,!
/ /r M
j
/
i
•CB-4 i
*'A_I?
J
/
y
I
' N
/tf
A-ioy
r-f1
1 \
f
1 j
.SG-17 (
T3S.
A ALLUVIAL WELLS
• DEEP GROUND WATER WELLS
® SPRING OR SEEP
I Mil*
J Kilometer
Figure 5-24. Springs and seeps in the Tract C-b area (C-b Shale Oil Venture, 1977b).
-------
4.0
3.0
2.0
1.0
_ 1.0
•6
oo g
en n!
0.8
0.6
0.4
0.2
SPFUNGW-3(S-10)
I
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Figure 5-25. Hydrographs of springs near Tract C-a, 1974-1976 (C-b Shale Oil Venture, 1977b).
-------
varies seasonally, declining in the spring when the alluvium is recharged and
rising in the autumn. Daily flow measurements were taken on spring S-9 in an
attempt to correlate spring discharge with barometric pressure fluctuations,
but no correlation was observed, indicating that the spring source probably
was not a deep, confined aquifer.
Alluvial Aquifers
Some of the springs are supplied by groundwater from the alluvium which
lines the valley floors. Observed water levels in the alluvium peak in Ouly
and diminish to a minimum by February or March. This cycle is out of phase
with the snpwmelt supply, which peaks in March and April and is low in the
summer. The lag is probably due to infiltration and seepage time.
The saturated thickness of the alluvium around Tract C-b ranges from 10
to 72 feet. The transmissivity varies radically, from 121 to 10,000 ft2
per day. The variation probably depends on the nature of the alluvium pene-
trated and is not correlated with drainages or well depth. Specific yields
averaging about 15 percent were also calculated from aquifer tests.
Deep Aquifers
Upper Aquifer--
The entire Tract C-b area is underlain by the Upper Aquifer. Figure 5-21
illustrates the configuration of this aquifer. It is bounded on the bottom
by the Mahogany Zone confining bed and extends upward into the Uinta Forma-
tion. The Four Senators oil shale sequence, located at about the middle of
the aquifer, serves as an aquitard, partially dividing the aquifer. Principal
aquifer zones occur about midway between the Mahogany and Four Senators Zones
and at the Green River Tongues in the Uinta Formation. The Black Sulfur
Tongue seems to bound the aquifer on the top.
A tentative map of the potentiometric surface of the Upper Aquifer is
provided in Figure 5-26. The gradient is toward the north at about 100 feet
per mile. The curvature and increased separation of the potentiometric lines
to the east are caused by discharge of the aquifer to Piceance Creek. Near
the center of the tract, well SG-6-3 has a head 9 feet higher than that of
well AT-1C-3, which should be upgradient of it. However, the piezometers in
these wells are not perforated over the same intervals, and the small section
near the Mahogany Zone, which SG-6-3 is perforated opposite, may have a higher
head than the thicker interval with which AT-1C-3 is in contact. If the in-
dicated averages of head truly are representative, they indicate a recharge
area near these wells. The source of any such recharge is not apparent, since
the wells are on the top of a ridge and nearby canyons are small, with ephem-
eral water courses. For these reasons, the 6500-foot equipotential line does
not reflect the values from these wells.
Aquifer parameters were determined through a long-term aquifer test. The
well AT-1 was pumped for 24 days at a rate varying from 480 to 365 gallons per
minute, allowed to recover for 5 days, then pumped for 5 days at about the
same rate. Several shortcomings of this test necessitated reevaluation of the
86
-------
e*>° T.3S.
_ *» n
LEGEND
A ALLUVIAL WELLS
• DEEP GROUND WATER WELLS
Figure 5-26.
Potentiometric surface of Upper Aquifer, Tract C-b.
(C-b Shale Oil Venture, 19775).
test and the data analysis by GE--TEMPO. A primary problem is the variation
in discharge during what was supposed to be a constant discharge test. This
variation amounted to about 24 percent of the initial rate. This decrease in
pumping was nowhere accounted for in the subsequent analyses. A second prob-
lem is the uncertainty of response to longer pumping. The drawdown curves
typically showed a normal curve, then a flattening at a later time. Such a
response is characteristic of fractured rock aquifers, but is usually followed
by another steepening of the curve, a result of the low permeability of the
interfracture medium. The aquifer test was not carried out for long enough
to determine if this late response would, in fact, occur. The transmissivity
values which were published in the Tract C-b baseline report were taken from
the early-time, steep curves, which gave low T figures. If the aquifer does
respond to long-term pumping with a classic fracture response, these figures
may be approximately correct, but the aquifer test simply was not long enough
to determine what the response may be. A correction for residual drawdown
should be made.
This problem was compounded by allowing only a 5-day measured recovery
after the 23-day aquifer test. This period was not long enough to allow
87
-------
collection of the crucial late-time recovery data, which could have been of
the most value in interpreting late-time response.
Finally, the analysis of the recovery data was invalid. The correct
straight-line method of analysis of recovery data is plotting residual recov-
ery versus log time since pumping started, divided by time since pumping
stopped. A theoretically less reliable, but still valuable, method is to
plot estimated ("calculated") recovery versus time since pumping stopped. An
estimate of the storage coefficient may be obtained by this method. The AT-1
recovery data, however, were analyzed during the baseline studies by a normal
Jacob method of analysis of drawdown (in psi) versus time since pumping
stopped. This analysis is theoretically invalid, especially for storage
coefficient analysis.
Another important factor was the method of measurement of drawdown. In-
stead of employing tapes or sounders, which are accurate to within a tenth of
a foot if carefully used (Davis and DeWiest, 1966), water depth was measured
with pressure gages accurate to only one-half foot. These gages frequently
malfunctioned and thus data from many observations were lost. Drill stem
tests were also performed to estimate aquifer permeability (Tables 5-5 and
5-6).
The net effect of all these errors and uncertainties is difficult to
determine. Some of the effects counteract each other by tending to cause
overestimation or underestimation of transmissivity. However, the net effect
is probably an underestimation of transmissivity. Reported results are tabu-
lated in Table 5-7. The average transmissivity is 168 ft2 per day and the
storage coefficient is about 5 x 10"^. The actual transmissivity, accord-
ing to reanalysis of the data, would probably be about 225 ft2 per day.
Reevaluation indicates a storage coefficient of 3 x 10"^, but this differ-
ence is not significant. The higher transmissivity value is supported by
USGS pumping tests. The average of six aquifer tests in the vicinity of
Tract C-b reported in Weeks et al. (1974) is 405 ft2 per day.
Leakance values, estimated from type-curve matching (Table 5-7), were
small, showing that the water level in any aquifer was not affected by pump-
ing any other aquifer. A computer solution of the Neuman and Witherspoon
leaky aquifer equation was developed which indicated that the vertical hy-
draulic conductivity was less than 5 x 10~7.
Fractured rock aquifers are typically anisotropic with greatest permea-
bility in the direction of major fracturing. An evaluation of data from
wells S6-6, SG-10, and SG-11 during the AT-1 aquifer test using R.E. Glover's
equations for anisotropic analysis yielded a 9:1 ratio of maximum to minimum
permeability, with the maximum in an east-northeast direction (C-b Shale Oil
Venture, 1977b). Reevaluation by TEMPO of the AT-1B, AT-1C, and AT-1D data
from the same aquifer test by GE--TEMPO using Hantush's method (Kruseman and
DeRidder, -1976) yielded a 2:1 ratio with the maximum permeability N48W, The
maximum transmissivity (assuming an effective transmissivity of 225 ft2 per
day, as discussed above) is 318 ft2 per day and the minimum is 159 ft2
per day. The 2:1 anisotropy seems more reasonable than 9:1. The N48W orien-
tation is much more likely, as the regional joint strike is northwest. Nearby
-------
TABLE 5-5. S6-17 DRILL STEM TESTS
Drill stem Interval Permeability
test no. (feet) (md)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
386
788
822
866
919
967
1,017
1,066
1,116
1,164
1,200
1,215
1,224
1,251
1,280
1,309
1,327
1,373
1,423
1,423
1,473
1,428
- 436
- 808
- 869
- 919
- 970
- 1,017
- 1,067
- 1,116
- 1,166
- 1,212
- 1,224
- 1,224
- 1,251
- 1,271
- 1,309
- 1,336
- 1,373
- 1,419
- 1,470
- 1,470
- 1,522
- 1,522
N.D.a
N.D.
11.0
12.7
34.0
10.7
19.9
20.0
8.0
185.0
21.2
20.8
300
8.0
13.0
N.D.
52
15
N.D.
23.9
3.0
4.7
Drill stem Interval Permeability
test no. (feet) (md)
23
24
24(J)b
25
25(J)
26
26(J)
27
28
28(J)
29
30
30 (J)
31
32
33
34
35
36A
36B
37
1,512
1,561
1,561
1,618
1,618
1,668
1,668
1,711
1,768
1,768
1,818
1,869
1,869
1,918
1,966
2,018
2,120
2,220
2,320
2,315
2,395
- 1,572
- 1,572
- 1,622
- 1,640
- 1,670
- 1,679
- 1,720
- 1,770
- 1,779
- 1,820
- 1,870
- 1,880
- 1,910
- 1,970
- 2,020
- 2,070
- 2,170
- 2,270
- 2,370
- 2,370
- 2,460
4.0
23.0
N.D.
4.0
1.6
30.0
7.3
6.0
42.0
9.8
2.0
275
30
4.0
169
N.D.
30
N.D.
N.D.
N.D.
35.0
aN.D. = No data obtained due to equipment malfunction, analytical problems,
no water injection, packer leakage, etc.
b(J) = Jetting test.
89
-------
TABLE 5-6. SG-17 MULTIPACKER TESTS
Multipacker
test no.
1
2
3
4
5
6
Interval
(feet)
1,089
1,123
1,147
1,184
1,338
1,422
- 1,114
- 1,148
- 1,172
- 1,209
- 1,363
- 1,477
Permeability
(md)
75
N.D.a
92
N.D.
N.D.
N.D.
TABLE 5-7.
= No data obtained due to equipment
malfunction, analytical problems, no
water injection, packer leakage, etc.
RESULTS OF AQUIFER TESTS ON OIL SHALE LEASE
TRACT C-b (C-b Shale Oil Venture, 1977b).
Well no. Transmissivity
(string no.) (ft^ per day)
Upper Aquifer
SG-10
AT-1A (3)
SG-6
AT-1D (3)
AT-1B
AT-1C
SG-11
Lower Aquifer
AT-1C (2)
AT-1C (1)
AT-1D (1)
SC-6 (1)
AT-1D (1)
SG-6 (2)
SG-10 (10)
233
159
212
130
162
128
155
20.4
40.9
35.4
91.9
43.8
35.7
14.7
Storage
coefficient
4.21 x 10"4
4.23 x 10"4
1.68 x 10"3
2.97 x 10"4
-4
3.71 x 10 *
-4
2.73 x 10
-5
6.92 x 10 D
1.22 x 10"4
1.21 x 10"5
-R
2.67 x 10 D
5.30 x 10"4
4.19 x 10"4
_c
6.84 x 10 D
3.92 x 10'5
Leakage
4.26 x 10"7
6.10 x 10"6
1.27 x 10"6
8.05 x 10"7
-fi
1.56 x 10 D
-fi
1.23 x 10 °
_7
5.90 x 10
1.96 x 10"5
3.93 x 10"7
_7
8.77 x 10 '
—
__-
-fi
3.44 x 10 b
6.88 x 10"6
90
-------
faults mapped in Weeks et al. (1974) strike N68W. Bredehoeft et al. (1976)
reported that hydraulic fracturing experiments indicated a regional fractur-
ing orientation of N70W. The Tract C-a Detailed Development Plan (RBOSP,
1976) reported that the major joint set strikes N56-76W. The east-northeast
orientation calculated for Tract C-b is nearly perpendicular to the regional
trend, while N48W is quite close to it. The flow net in Figure 5-27 is drawn
using these anisotropy values and orientations by the anisotropic flow net
transform method. The anisotropy causes the flow lines to diverge by more
than a mile across the tract.
Lower Aquifer—
The Lower Aquifer under. Tract C-b extends from the lower half of the
Mahogany Zone to the R (rich oil shale) -4 zone (Figure 5-21). Major water-
producing zones are the lower part of the Mahogany Zone, and the lower half
of the R-5 with the L-4 below it. The upper half of the R-5 zone forms an
intermediate aquitard and the lower R-4 zone the base of the aquifer. The
SG20*
•SGI 9
DIRECTION OF MAXIMUM
PERMEABILITY
1 INITIAL IN SITU RETORT FIELD
2 MINE SUPPORT AND ACCESS
3 MINED ROCK AND RAW SHALE DISPOSAL.
COTTONWOOD GULCH
4 COTTONWOOD IMPOUNDMENT DAM
5 OIL STORAGE
6 WASTEWATER POND
7 STACKS
8 OIL TREATMENT
9 GAS TREATMENT
10 SORGHUM GULCH
11 IMPOUNDMENT DAM
ASG-8
KEY TO WELLS
UPPER AQUIFER
• LOWER AQUIFER
A DUAL COMPLETIONS
Figure 5-27. Anisotropic flow net of Upper Aquifer superimposed
on Tract C-b initial development plot plan.
91
-------
R-4 is just above the saline (high resistivity) zone at the base of the Para-
chute Creek Member. A few thin strata, containing water with high dissolved
solids from direct contact with the saline zone, lie below the R-4.
The head of the Lower Aquifer is everywhere (on Tract C-b) below that of
the Upper Aquifer. The potentiometric surface of the Lower Aquifer is mapped
in Figure 5-28. The curvature of the lines to the east indicates possible
discharge to Piceance Creek. No anomaly similar to that in the Upper Aquifer
was found.
The design of the aquifer test performed in the Lower Aquifer was simi-
lar to the Upper Aquifer test. The well was pumped for 18 days at 130 gallons
per minute, allowed to recover for 8 days, pumped for 8 more days, and allowed
to recover for 20 days. Factors affecting the results of this test are simi-
lar to those discussed above, except that here the pumping rate was fairly
constant. However, another influence in this test was the fact that the well
depth was only 1700 feet, penetrating only a little more than half the aqui-
fer. Partial penetration will cause the transmissivity to be underestimated..
The Tract C-b baseline report transmissivity values are listed in Table 5-7.
The average is 40.4 ft2 per day. Reanalysis indicates that a more repre-
sentative transmissivity is about 70 ft2 per day. The high T value is sup-
ported by the average of nearby Lower Aquifer pumping tests reported in Weeks
et a]. (1974) of 100 ft2 per day. The average coefficient is 1.73 x 10"4
(10~4 to 5 x 10~5 is probably a reasonable range) (C-b Shale Oil Venture,
1977b). On the basis of barometric efficiency calculations, the baseline re-
port concluded the porosity is about 0.05, a reasonable value.
The baseline report did not give figures for Lower Aquifer anisotropy,
but stated that the maximum transmissivity was in a more north-south direction
than the Upper Aquifer. Reanalysis showed that the results varied consider-
ably when different combinations of wells were used. The results considered
most reliable were from wells AT-1A, 56-10, and SG-6. Using Hantush aniso-
tropic analysis (Kruseman and DeRidder, 1976), the direction of maximum trans-
missivity was N81W, in fairly good agreement with the geologic evidence. The
maximum transmissivity (assuming an effective transmissivity of 70 ft2 per
day) was 146 ft2 per day and the minimum was 33 ft2 per day. The ratio
between them is about 4:1. This conclusion i's tentative due to the data
problems.
SURFACE WATER HYDROLOGY
The Piceance Basin is drained by two stream systems: Piceance Creek and
Yellow Creek (Figure 5-29). Most of the tributaries are ephemeral, but a few
of the largest are perennial in the lower reaches. Two or three years of data
now extst for most of the tributaries flowing through the oil shale lease
tracts.
Piceance Creek maintains a reasonably constant base flow of groundwater.
Peak flows occur in the spring, at the time of snowmelt. Summer thunderstorms
can also raise the flow. The maximum, minimum, and mean monthly flows are
shown in Figure 5-30. The discharge at Rio Blanco is nearly unaffected by
92
-------
6400
GO
6500
5600
S-8
fl SG-II
i / •
fSG-IOA*«SG_IO £y
T3S
A ALLUVIAL WELLS
• DEEP GROUND WATER WELLS
Ki lorneler
Figure 5-28. Lower Aquifer potentiometric map, Tract C-b.
-------
108°
EXPLANATION
A- STREAMFLOW GAGING STATION -
._ Number refers to station listed in
& table 2
___«• MOFFAT CQ-.
> r/ f
- 51—•_ ; c--r
^\ -•—-^—"^ s7
i..
A.R0^:->.
•^, %
-------
5000
40OO -
3000
5000
4000
3OOO
2000
1000
C. Piceance Creek at White River
-6
u-5
A. Piceance Creek at Rio Blanco
B. Piceance Creek below Ryan Gulch
I- 5
— 3
OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT
Figure 5-30.
Maximum, minimum, and mean monthly runoff from Piceance
Creek at Rio Blanco, below Ryan Gulch, and at White River.
95
-------
human activity, but the flows at the two lower stations are altered by diver-
sion for irrigation of hay fields and pastureland. Approximately 5100 acres
are irrigated. Large withdrawals in April and May at the beginning of the
growing season greatly modify the spring flood peak.
The mean annual discharge at the White River amounts to 14,520 acre-feet
(17.6 cubic feet per second). The mean annual high flow is 800 cubic feet
per second and the calculated 20-year, 7-day, low flow is 10.4 cubic feet per
second.
Yellow Creek, with a smaller drainage basin, contains much less flow
than Piceance Creek. The mean annual flow is only 1.4 cubic feet per second.
The mean annual high flow is 388 cubic feet per second, but flows less than
1 cubic foot per second are common and, in dry years, the stream may at times
be dry. Runoff (Figure 5-30) is affected by withdrawal of water for the irri-
gation of about 200 acres. Because of the small basin size, summer-thunder-
storms have a proportionately greater effect than they do on Piceance Creek.
For the same reason, the variability of flows is greater.
96
-------
SECTION 6
EXISTING WATER QUALITY
The hydrologic system of the Piceance Basin may be divided into four
general parts: surface water, alluvial aquifers, the Upper Aquifer, and the
Lower Aquifer. The lithology of the rocks over or through which the water
flows largely determines the water quality. Some broad generalizations on
the regional water quality may be made.
GENERAL BASIN WATER QUALITY
Surface water quality within the Piceance Basin is widely variable. The
streams pick up salts from runoff over saline soils as they flow downstream.
Salts already present are concentrated by evapotranspiration. The major con-
tributor of salts is probably influent water ultimately derived from the sa-
line groundwaters, particularly from the Lower Aquifer.
The total dissolved solids content of the surface waters increases from
around 600 mg/1 near the headwaters of Piceance Creek to 2000 mg/1 at the
White River. The water is a mixed-cation bicarbonate to a sodium bicarbonate
type.
The water of the Lower Aquifer displays a similar pattern of salinity.
In this case it is due to dissolution of saline minerals as the groundwater
flows toward the discharge area. Some beds at the base of the leached zone
are nearly pure nahcolite and halite. The total dissolved solids content in-
creases from about 500 mg/1 to nearly 40,000 mg/1 (Figure 6-1). The average
is 9400 mg/1. Obviously, this salinity renders much of the water in the
aquifer unsuitable for many uses.
The water is of fairly pure sodium bicarbonate type, with chloride as
the only other major ion. Calcium and magnesium are very low, partly because
the minerals dissolved are primarily sodium salts and partly because of con-
centration control by calcite solubility limits. Chloride is significant be-
cause of halite in the aquifer. Sulfate concentrations are relatively low,
averaging about 80 mg/1. Certain trace elements are also extremely high.
Even in regions of lower salinity, the fluoride content is over 10 mg/1 and
may reach over 60 mg/1. In the high salinity region, barium concentrations
of 13 mg/1, boron concentrations of 120 mg/1, and lithium concentrations of 6
mg/1 have been measured.
The Upper Aquifer is not characterized by these extreme salinity and
trace element concentrations. Dissolved solids do increase from 350 mg/1
97
-------
EXPLANATION
• WELL
-7000 LINE OF EQUAL DISSOLVED-SOLIDS CONCENTRATION
Interval, in milligrams per litre, is variable
108°
Base from US.Geological Survey
State base map, 1969
0
10
I
15 MILES
I
10
15 KILOMETRES
Figure 6-1. Concentration of dissolved solids in the Lower Aquifer,
May-September 1973 (Weeks et al.t 1974).
near the recharge areas to over 2000 mg/1 in the basin center (Figure 6-2),
but this increase is not accompanied by high trace elements. The water is of
a similar type to that of the Lower Aquifer, with a sodium bicarbonate char-
acter and moderate chloride. However, fluoride is very low, and so are other
trace elements.
The type of the alluvial aquifer water is quite similar to that of the
Upper Aquifer. The dissolved solids range from 500 to 6700 mg/1. It is of a
sodium bicarbonate type with a higher sulfate concentration than the other
98
-------
-500
EXPLANATION
WELL
SPRING
LINE OF EQUAL DISSOLVED-SOLIDS CONCENTRATION
Interval 500 milligrams per litre
108°
Base from US.Geological Survey
State base map, 1969
0 5
I i i i i I
15 MILES
I i i ' ' I
0 5
I
10
15 KILOMETRES
Figure 6-2. Concentration of dissolved solids in the Upper Aquifer,
May-September 1973 (Weeks et a"!., 1974).
groundwaters of the area, averaging 430 mg/1. In general, fluoride content
is low. The average dissolved solids content is 1750 mg/1, much lower than
the maximum of 6700 mg/1. The areas with high dissolved solids content are
near faults which .allow discharge of high salinity water from the deep aqui-
fers to the alluvial aquifer (Weeks et a!., 1974).
99
-------
The nature of the groundwater in the Piceance Sasin may cause several
problems for groundwater development for oil shale production. Water of un-
der 1000 mg/1 total dissolved solids will be desirable for many of the pro-
cesses involved. While much of the Upper Aquifer possesses water of this
quality, only a small fraction of the more productive Lower Aquifer does.
While regional trends in water quality may be described in general
terms, the pattern on a smaller scale, such as an oil shale lease^tr^act, is
much more complex. The major control over water quality is lithology.
Changes in lithology are a result of the depositional environment, which was
a complex system dependent on fluctuating sedimentary, biological, and chemi-
cal parameters. The sequence of rock resulting from this environment is
characterized by great lateral continuity, and great vertical differences in
rock type, strength, kerogen content, and soluble salt content. Each of these
layers has responded differently to post-depositional tectonic stresses, and
response within layers to hydraulic stress is not homogeneous.
The results of this geologic framework may be pictured by imagining two
wells very close together which are perforated over exactly the same inter-
vals. The perforated interval contains two fractured strata of equal hydrau-
lic conductivity. One stratum contains abundant saline minerals, the other
very little. One well intersects a fracture in the upper stratum but not in
the lower, while the other well intersects a fracture only in the lower stra-
tum. The water from the two wells will be of drastically different quality
even if the hydraulic conductivity is the same.
In fact, this situation is complicated even more by the differing hy-
draulic conductivities of different strata. Some fine-grained beds with high
kerogen content are resistant to fracturing or jointing and form effective
confining beds. This allows the existence of head differences between satur-
ated layers, which creates mixing of waters in regions of interconnection,
such as in well bores. On a small scale, the system may more nearly resemble
10 to 20 very thin aquifers than 2 large ones.
This complexity necessitates extreme care in analyzing water quality
data. Ideally, each water-bearing interval shpuld be individually isolated
at several locations. If this is not possible, all wells should at least be
perforated over the same stratigraphic intervals or over a small number of
different intervals. On both Tracts C-a and C-b, observation wells are per-
forated over a large number of different stratigraphic intervals, few of which
correspond the others. Thus, the individual tract results should be viewed
with great caution until more complete data are obtained.
TRACT C-a GROUNDWATER QUALITY
General Description
About 32 wells were drilled and monitored during the Tract C-a baseline
monitoring period. Most of these wells were perforated in, or open to, both
aquifers. Most holes were 6-3/4 inches in diameter, with the main aquifer
zones separated by means of a mechanical packer. Monitored intervals in the
Upper Aquifer were usually accessed by the insertion of perforated 2-3/8-inch
100
-------
tubing. The lower portion of the hole, below the packer, was usually left
open, with 2-3/8-inch tubing leading from the packer to the surface.
Data on alluvial water quality are summarized in Table 6-1. The temporal
variation of some of these parameters is shown in Figure 6-3. The decrease
in most parameters around April is probably due to dilution of aquifer water
by infiltrating snowmelt (RBOSP, 1977b).
The compositions of water samples from wells in the Upper and Lower
Aquifers are plotted on a trilinear diagram in Figure 6-4. The variation in
composition of samples from the same aquifers is much larger than that from
Tract C-b (see following discussion). In general, the Upper Aquifer waters
contain 35 to 70 percent sodium plus potassium, 10 to 40 percent calcium, and
roughly equal magnesium. The anion composition is an approximately equal
sulfate-bicarbonate type, with less than 10 percent chloride plus fluoride.
The Lower Aquifer exhibits a much wider range of composition. Sodium
generally comprises a higher percentage of the cations (60 to 100 percent),
while calcium is much lower (0 to 10 percent). Magnesium is 0 to 25 percent.
The anions are dominated by carbonate plus bicarbonate (60 to 100 percent),
with 0 to 35 percent sul fate and minor chloride plus fluoride. Many samples
fall outside of these ranges, some in the trilinear diagram field of the other
aquifers and some are completely different from all the rest. Several of the
Lower Aquifer wells have water higher in magnesium and sulfate than any of
the Upper Aquifer wells. While these anomalous samples are difficult to ac-
count for, the general explanation of the water quality distribution is pro-
bably that the Upper Aquifer water quality is influenced by leaching of the
oxidized products from surface weathering, while the Lower Aquifer is chemi-
cally reduced and more heavily affected by the leaching of soluble salts
within the aquifer.
The lateral distribution of the major cations and anions in the Upper
and Lower Aquifers was mapped as part of this study. However, the distribu-
tions made sense neither in relation to the geochemical system nor in relation
to each other. The likely explanation is that the wells are not consistently
perforated with respect to the stratigraphy and water quality (which reflect
the mineralogy and residence time within the individual strata). The situa-
tion on Tract C-a is further complicated by the complex structure and partic-
ularly the widespread faulting.
Water Type Comparisons
The compositions of the various well samples were compared with pH, TDS,
and temperature in order to determine more exact relationships. Figure 6-5
shows a fair correlation of composition with pH in the Upper Aquifer. The pH
of most Upper Aquifer samples is below 7.4. The Lower Aquifer exhibits a
wide range of pH, from below 7.0 to about 8.0, but the correlation with com-
position is good. Most of the Lower Aquifer samples with high calcium, mag-
nesium, and sulfate have pH values below 7.4, while those with high sodium
and bicarbonate content have pH values above 7.5.
101
-------
TABLE 6-1. SUMMARY OF WATER QUALITY FROM ALLUVIAL AQUIFERS, TRACT C-a
(RBOSP, 1977b)
Concentration
Constituent
General water quality measures
Conductivity (y mhos/cm)
Dissolved solids (mg/1)
Alkalinity (mg/1 CaCOj
PH
Hardness (mg/1 Mg, Ca)
Temperature (°F)
Fecal col i forms (per 100 ml)
Total col i forms (per 100 ml)
Major inorganics (mg/1)
Bicarbonate
Carbonate
Chloride
Sulfate
Sulfide
Fluoride
Nitrate (N03)
Nitrite (N)
Ammonia (N)
Calcium
Magnesium
Sodium
Potassium
Phosphate (PO^)
Organ ics (mg/1)
Biochemical oxygen demand
Dissolved organic carbon
Phenol ics (ug/1)
Kjeldahl nitrogen
Maximum
2,252
1,650
880
7.2
810
57.2
40
250
680
48
41
720
1.6
0.7
165
150
5.3
210
145
350
14
0.1
3.9
292
13
8.8
Minimum
860
610
310
6.0
280
42.0
<10
20
360
<0.1
1.3
150
<0.1
0.1
0.1
<0.01
<0.1
39
3.7
66
<1
0.1
3.8
2
<1
<0.1
Geometric
mean
1,288
111
383
6.3
448
48.8
20
71
459
0.3
12.8
297
0.2
0.3
3.9
0.22
0.4
96
57
151
3:7
0,1
3.9
18.7
2
1.8
Number of
analyses
67
67
67
63
62
67
2
2
67
67
65
67
11
66
61
19
14
67
65
67
22
20
2
55
11
22
(continued)
102
-------
TABLE 6-1. (continued)
Concentration
Constituent
Organics (mg/1) (con't.)
Cyanide
MBAS
Trace constituents (yg/1)
Aluminum
Arsenic
Barium
Beryl 1 i urn
Boron
Bromide
Cadmi urn
Chromi urn
Copper
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Strontium
Zinc
Radiological constituents
(pCi/1)
Gross alpha
Radium 226
Gross beta
Maximum
0.02
< 0.01
1,200
<100
< 1,000
600
27,000
900
1,100
200
2,400
28,000
1,000
15,000
<10
<100
200
<100
<100
5,000
3,200
31
1
35
Minimum
< 0.01
< 0.01
<100
<10
< 1,000
< 20
< 10
< 10
< 10
< 10
< 10
< 50
10
< 50
< 1
<100
10
<10
<10
1,400
10
0.2
0.1
1.0
Geometric
mean
0.01
< 0.01
142
-------
SULFATE
NJTRATE
HCO3
MAGNESIUM
CHLORIDE
CALCIUM
TEMPERATURE
HARDNESS
DEPTH
HIGH
o
<
cc
iu
O
z
o
u
K-
Z
UJ
O
O
LOW
APRIL 1 1975
APRIL 1 1976
BOX ELDER GULCH
G-S S-7
HIGH
o.
cc
z
UJ
u
z
o
o
I-
UJ
CO
o
o
LOW
APRIL1 1975
APRIL 1 1976
CORRAL GULCH
G-S S-8
Figure 6-3.
Time trend plots for concentrations of chemical
constituents in Tract C-a alluvium (RBOSP, 1977b)
104
-------
TRACT C-A
LEGEND
LOWER AQUIFER
UPPER AQUIFER
Figure 6-4.
Trilinear diagram of water quality data for Upper and
Lower Aquifers, Tract C-a (data from RBOSP, 1977b).
105
-------
TRACT C-o
pH
UPPER LOWER
AQUIFER VALUE AQUIFER
• < 7.0 O
•» 7.0-7.4 6
• 7.5-79 a
• >8 0 O
8 s
Figure 6-5. Trilinear diagram comparing inorganic composition of
groundwaters to pH level, Tract C-a (data from
RBOSP, 1977b).
106
-------
Water Type versus IDS —
A fair correlation exists between IDS and composition, illustrated in
Figure 6-6. Although most Upper Aquifer samples have a dissolved solids con-
tent below 1300 mg/1, there is little correspondence between composition var-
iations and IDS. The correspondence in the Lower Aquifer, however, is good,
with a trend of increasing TDS with increasing sodium bicarbonate content.
Several Upper Aquifer wells possess a dissolved solids content above 1300
mg/1. Wells TO 3 and CE 703 both have a distinct "Lower Aquifer" composition
and dissolved solids content to match. The gradient at the northeast corner
of the tract where these wells are located is favorable for upward leakage.
Wells G-S 10 and G-S 12 are very close to a major fault zone, but the inter-
aquifer gradient does not favor upward leakage. Three Lower Aquifer wells,
TRACT C-Q
TOTAL DISSOLVED SOLIDS
UPPER LOWER
AQUIFER VALUE AQUIFER
• < 700 O
• 700-0 0
IOOO-< I3OO a
o
Figure 6-6.
Trilinear diagram comparing inorganic composition of
groundwaters to total dissolved solids concentration,
Tract C-a (data from RBOSP, 1977b).
107
-------
in particular CE 707, G-S 1 and CE 708, have dissolved solids below 700 mg/1.
Wells CE 707 and G-S 1 are both near the same major fault and downward leak-
age would be occurring here. CE 709 is not near any faults. Its composition
is thus anomalous.
Water Type versus Water Temperature--
The comparison of water temperature and composition in Figure 6-7 indi-
cated a good correlation between the two. Most Upper Aquifer "type" water is
below 56°C and all is below 61°C. The only Upper Aquifer wells with tem-
peratures above 61°C are CE 702 and TO 3. This high temperature, combined
with TDS and pH correlation, very strongly indicate a Lower Aquifer origin
TRACT C-0
TEMPERATURE (°F)
UPPER LOWER
AQUIFER VALUE AQUIFER
W ^51* o
* 5r-<56* a
• 56"-<6r D
Figure 6-7.
Trilinear diagram comparing inorganic composition of
groundwaters to water temperature, Tract C-a (data
from RBOSP, 1977b).
108
-------
for the water in these wells, probably through upward leakage. Although sev-
eral Lower Aquifer wells show atypically low temperatures; no pattern or cor-
relation with IDS or pH is apparent.
Water Type versus Sampled Interval —
A correlation of water quality with interval sampling was attempted us-
ing the intervals shown in Figure 6-8. Unfortunately, few consistent rela-
tions between composition and interval could be found. This poor correlation
probably is a result of the complexity of the local hydrogeology. The simple
strati graphic framework is distorted by folding and faulting. The faults
serve as hydraulic barriers within aquifers and as conduits between aquifers.
They also may juxtapose otherwise horizontally separated strata. The root
cause of the wide variability between analyses from the same aquifer and the
lack of meaningful area-wide trends is probably the inconsistent perforation
with respect to the stratigraphy, but this inconsistency is vastly complicated
by the structural problems.
Tract C-a water quality data have also been analyzed using statistical
techniques, such as development of correlation sign matrices, varimax factor
loading matrices, and discriminant function analysis (RBOSP, 1977b). Major
conclusions reached were that calcium, magnesium, and sulfate were inversely
correlated with the rest of the major ions and pH in the Upper Aquifer, while
the rest were directly correlated. Calcium and sulfate were inversely related
to bicarbonate, carbonate, fluoride, sodium, and TDS in the Lower Aquifer.
The varimax factor analysis loading scores indicated the possibility of aqui-
fer interconnection at wells CE 702 and G-S 6. Scores at wells AM 3 and G-S
12, along the rise of the Sulfur Creek Anticline, showed the same possibili-
ties there. Possible downward leakage was indicated at holes G-S 10, G-S Ml,
and G-S 1. The conclusion of upward leakage at the northeast corner of the
tract was strongly supported.
Comparison of Upper and Lower Aquifers
Comparison of samples from the two aquifers demonstrated that the con-
centration of many of the major ions is higher in the Lower Aquifer, with the
exceptions of calcium (which is lower by 75 percent), magnesium (which is
lower by 60 percent), and sulfate (which is lower by 65 percent). These fig-
ures support the general explanation of water quality distribution presented,
as does a theoretical solubility constant analysis. This analysis showed
that some Upper Aquifer samples were saturated or supersaturated with respect
to calcite, but none with respect to gypsum.
Summary
In summary, the Upper Aquifer contains mostly sodium, calcium-magnesium-
bicarbonate-sulfate water. The Lower Aquifer water varies from sodium-
calcium-magnesium-bicarbonate-sulfate to sodium-bicarbonate. More detailed
descriptions, either on an area! or stratigraphic basis, cannot be made with
the present data. Upper Aquifer wells TO 3 and CE 702 are in an area of up-
ward leakage from the Lower Aquifer. G-S 11 Upper shows many Lower Aquifer
characteristics, but upward leakage seems unlikely. Lower Aquifer well G-S 1
109
-------
WELL:
S M
s i
•
-------
may demonstrate evidence of downward leakage from the Upper Aquifer. Upper
Aquifer well TO 1 and Lower Aquifer well CE 709 are highly anomalous, without
any ready explanation.
TRACT C-b GROUNDWATER QUALITY
General Description
During the course of the Tract C-b Baseline Monitoring Program, about 15
wells in the Upper and Lower Aquifers and 10 wells in the shallow alluvium
were regularly monitored for water level and a wide variety of chemical con-
stituents (C-b Shale Oil Venture, 1977b). The wells were drilled with diame-
ters ranging from 13 to 6 inches, but several of them had as many as three
strings of 2-3/8-inch tubing, perforated at selected intervals, set within
the uncased well bore. These tubing strings are designated by a numeral after
the well number; for example, "SG-1-2" is the second string in well SG-1.
The well bores were gravel-packed after placement of the tubing. Several
wells were recompleted after the original monitoring and these are designated
with an "R" after the well number. More recompletions are being planned.
The intervals against which the various wells and strings are perforated
or open are indicated on Figure 6-9. As previously discussed, the monitoring
wells should ideally be open to identical stratigraphic intervals of the
aquifer due to the highly stratified nature of the aquifer. Unfortunately,
only a few of the wells and strings are actually open over the sane intervals;
the rest are nearly randomly spaced. This problem greatly complicates analy-
sis of water quality distribution within the aquifer.
Alluvial well samples on Tract C-b have been collected by pumping, using
a submersible pump. Deep well samples have been collected by swabbing.
In Figure 6-10, the levels of the major anions and cations are plotted
on a trilinear diagram. General differences in water quality of the various
aquifers are apparent. Sodium and magnesium in water from the alluvial wells
both range between 30 and 50 percent, while calcium is between 15 and 25 per-
cent. The anions are dominated by carbonate and bicarbonate (45 to 65 per-
cent), with slightly less sulfate (35 to 55 percent), and only minor chloride.
Water quality in the springs and seeps is similar, with slight magnesium
and calcium. This may be due to higher solubility of calcium carbonate be-
cause of carbon dioxide from the soil atmosphere.
Upper Aquifer water quality shows a wide variation, but the composition
usually falls within the range of 50 to 90 percent sodium, 0 to 20 percent
calcium, and 0 to 30 percent magnesium. The anions are dominated by bicar-
bonate (40 to 95 percent), with 0 to 50 percent sulfate and only 0 to 10 per-
cent chloride and fluoride. The trend toward a higher proportion of sodium
and bicarbonate is also present in water from the Lower Aquifer, which con-
tains 90 to 100 percent sodium, and only 0 to 5 percent calcium and magnesium.
Carbonate and bicarbonate compose 60 to 95 percent of the anions and sulfate
only 0 to 15 percent, but chloride and fluoride are much higher, 5 to 40
percent.
Ill
-------
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;?:?
c
a ^
9 •«
•) C
!'I*!v!"l*!*!*!v
:X':W:|:|:|:|:
•
j 1
> x
> c
5x'S:
.
t>
i P
i <
:?:¥
j:|:jv'::
M
- a
c en
:•§:•
•:;X;X
•
"
u
c
a
,
*•'•'%
.
> c
•) a
) t
) t
1 0
;:•:•:•:
• '
g ?
D !r
9 C
D a
X;X;:
SS;
.
C "
> ;
> c.
> a
:?:¥:
'•'•'•S-:
1 ?
? (!
» U
i?S
•
j „
: 2 2 N o o to o
> « (/> c/> to
• •
:::::::S:;SS:;:;::g:;:;S:;:
••:¥::Xv::::::::Xv:;X:X:X;
.X
Figure 6-9. Intervals of perforation of wells on Tract C-b.
-------
TRACT C-B
LEGEND
UPPER AQUIFER
LOWER AQUIFER
SEEPS AND SPRINGS
ALLUVIAL WELLS
Figure 6-10.
Trilinear diagram presenting groundwater quality data
for Tract C-b (data from C-b Shale Oil Venture, 1977b).
The calcium and magnesium contents are probably lower because of precip-
itation of calcium carbonate and magnesium carbonate as bicarbonate increases
due to dissolution of more soluble nahcolite. Sulfate may also be controlled
by solubility of gypsum (C-b Shale Oil Venture, 1977b), but its distribution
may also be a result of environmental factors. Sulfate salts are not common
in the Green River Formation, and most sulfate probably originates from oxi-
dation of sulfides during near-surface weathering. Thus, sulfate would tend
to be more common in near-surface aquifers.
Water from wells, however, does not follow the pattern just discussed.
In the Upper Aquifer, wells SG-17-2, Cb-2, SG-8-2, SG-19, and SG-20 more
nearly resemble Lower than Upper Aquifer water quality. Well SG18A has
113
-------
anomalously high levels of sulfate. Lower Aquifer well SG-10R is completely
anew al o us.
An important portion of the description of water quality in any hydro-
logic system is the areal distribution of water quality parameters. This
provides information on the baseline water quality conditions against which
possible pollution can be measured and gives insight into processes acting
within the aquifer. Maps of the various water quality parameter levels at
each of the sampling points in the Upper and Lower Aquifers were prepared by
TEMPO. Inspection revealed that these distributions show little relation to
each other (with the exception of calcium and magnesium) and made little sense
in terms of the hydrogeologic framework. The explanation of this problem lies
in the inconsistency of the aquifer intervals sampled. The concentration of
quality constituents at each point reflects the differing depth zones and wa-
ter qualities of the intervals each well taps and not the areal differences
within a single representative interval.
Water Type Comparisons
Water Type versus pH—
In order to evaluate reasons for the different water quality types en-
countered, the types were compared with the pH, total dissolved solids con-
tent, temperature, and interval penetrated for each of the samples. Figure
6-11 illustrates the variation of pH with water type. The correlation of
type with pH is quite good, pH increasing with sodium bicarbonate as would be
expected. The pH of water from all springs and alluvial wells (except one)
is below 8.35. All Upper Aquifer samples below a type with 70 percent sodium
and bicarbonate have a pH of between 8.35 and 8.65, and all Lower Aquifer
samples (except SG-10, SG-11-1, and SG-17-1, which are all of very similar
type, with less than 70 percent carbonate and bicarbonate) are above 8.65.
This pattern is attributed to the dissolution of alkaline nahcolite within
the aquifer. Wells SG-11-1, SG-17-1, and SG-10 (which have very high TDS
levels, but high chloride, indicating dissolution of nonalkaline halite) have
a lower pH. Upper Aquifer wells SG-19, SG-20, and SG-17-2 also have pH lev-
els similar to those of the Lower Aquifer.
Water Type versus TDS—
Total dissolved solids content and composition are compared in Figure
6-12. Correlation within the Upper Aquifer, alluvial aquifers, and springs
is good, all samples with less than 90 percent sodium and carbonate plus bi-
carbonate having a TDS content of less than 1500 mg/1. Within the Lower
Aquifer, no trends are obvious. The range in TDS is very wide, ranging from.
693 to 42,000 mg/1.
The presence of nahcolite-rich water over a wide range of dissolved sol-
ids contents indicates that the nahcolite does not occur in a single rich
stratuD, but is distributed throughout the aquifers in varying degrees. How-
ever, all of the sodium chloride-rich waters have a very high TDS, indicating
a single halite-rich bed.
114
-------
TRACT C-b
pH
UPPER LOWER
AQUIFER VALUE AQUIFER
<8.35 o
8.35-865 D
> 8.65 a
AZVSZVXZVVVVVXAZ
Figure 6-11.
Trilinear diagram comparing inorganic composition of
groundwaters to pH level, Tract C-b (data from C-b
Shale Oil Venture, 1977b).
115
-------
Figure 6-12. Trilinear diagram comparing inorganic composition of
groundwaters to total dissolved solids concentration,
Tract C-b (data from C-b Shale Oil Venture, 1977b).
Water Type versus Water Temperature--
Water temperature and composition are compared in Figure 6-13. Trends
are apparent on only the broadest terms. All of the Upper Aquifer samples
below 90 percent sodium carbonate plus bicarbonate are below 18°C, with the
exception of SG-18A and AT-1C-3, which are below 20°C. Only samples with
sodium and carbonate plus bicarbonate above 90 percent are above 20°C, and
these are all Lower Aquifer with the exception of S6-19, SS-20, and SG-17-2.
This is as expected, cool recharge water being warmed by the geothermal flux
as it flows through deep aquifers. Water hotter than 20°C in some "Upper
Aquifer" wells strongly suggests the presence of Lower Aquifer water.
116
-------
TRACT C-b
TEMPERATURE (0C)
UPPER LOWER
AQUIFER VALUE AQUIFER
• < 16* O ~~
>20«
Figure 6-13. Trilinear diagram comparing inorganic composition of
groundwaters to water temperature, Tract C-b (data
from C-b Shale Oil Venture, 1977b).
Several Lower Aquifer wells have unusually cool water, between 16° and
18°C. These are AT-lC-1, SG-1-1, SG-6-2, SG-10R, and SG-11-2. The fact
that all of these, with the exception of SG-6-1, are open to an interval just
above and/or below the B-groove (the bottom of the Mahogany Zone) indicates
the probability of a zone of rapid flux (shorter heating time), and thus high
hydraulic conductivity in this interval.
Water Type versus Sampled Interval —
In order to obtain more information on the relationship of water quality
to the stratigraphic location within the aquifer from which the water came,
the aquifer was divided into stratigraphic sections, indicated on Figure 6-14.
117
-------
TRACT C-B
WATER QUALITY
LEGEND
° LOWER AQUIFER
• UPPER AQUIFER
STRATIGRAPHIC DESIGNATION
G2 GREEN RIVER FM 2
4 SENATORS
GREEN RIVER FM I
A GROOVE
MAHOGANY
RICH ZONE 6
LEAM ZONE 5
RICH ZONE 5
LEAN ZONE 4
RICH ZONE 4
4S
0 I
AG
M
R6
L5
R5
L4
R4
— Cl + F
Figure 6-14.
Trilinear diagram comparing inorganic composition of
groundwaters to stratigraphic section, Tract C-b (data
from C-b Shale Oil Venture, 1977b).
The basis of this assignment of aquifer positions is Figure 6-9.
parison reveals a great deal about aquifer conditions.
This com-
The uppermost portion of the bedrock aquifer system from which signifi-
cant data have been collected is the upper portion of the Green River Forma-
tion below the Four Senators Zone (designated GRF1 on Figure 6-9) and within
the Four Senators Zone. The single well open to only this interval is SG-6-3.
The data from this well indicate a composition very high in calcium, magne-
sium, and sulfate, compared to the rest of the deep aquifer system. TDS con-
tent is 1100 mg/1.
118
-------
The remainder of the monitored portion of the Upper Aquifer extends from
the upper Mahogany Zone to the middle of the GRF1 zone. Water quality from
this interval is typified by SG-21, SG-11-3, Cb-4, SG-1-2, and SG-18A. The
water from this interval is relatively lower in calcium, magnesium, and sul-
fate, with 60 to 75 percent sodium and 60 to 80 percent carbonate plus bicar-
bonate. Dissolved solids are lower than in the upper interval, averaging
about 600 mg/1. Although several of these wells also penetrate portions of
the upper interval, the water quality generally reflects origin in the lower
interval, indicating a higher transmissivity in the lower interval. This
conclusion is supported by the lower temperatures typical of the lower inter-
val, and by the lower sodium bicarbonate concentration, indicating a shorter
residence time. Additional confirmation comes from Tract C-b baseline stud-
ies: reported TDS levels at the end of the long-term aquifer test, which were
lower than that of swabbed samples from the same well, indicating greater pro-
duction from the salinity zone.
However, several wells, AT-1C-3, SG-9-2 and SG-10A, show a composition
intermediate between the two, indicating mixing of waters. The inhomogeneous
permeability of the fractured aquifers, as previously discussed, may explain
why some wells penetrating both intervals show little mixture and others much.
Two of the wells previously designated as Upper Aquifer wells (C-b Shale Oil
Venture, 1977b), in fact, appear to draw water from the Lower Aquifer. In
Figure 6-9, wells SG-19 and SG-20 are shown penetrating both aquifers. How-
ever, the composition of water from these wells is identical to Lower Aquifer
water, the dissolved solids content is in accord with Lower Aquifer levels,
and the temperature is the same as Lower Aquifer water and much higher than
Upper Aquifer temperatures. Therefore, in the future, these wells will be
included in the Lower Aquifer grouping.
Several wells which cannot be assigned to the Lower Aquifer nevertheless
exhibit compositions similar to Lower Aquifer water. These are SG-8-2,
SG-17-2, and Cb-2. Possibly, upward leakage from the Lower Aquifer is in-
fluencing these wells. SG-17-2 has a very high water temperature
(temperature data are not available for the other two wells). However, the
average head of the layers comprising the Upper Aquifer is somewhat higher
than the Lower Aquifer over the tract, and thus upward leakage is not likely.
The zone identified as having the best water quality within the Lower
Aquifer is the lower Mahogany Zone and Upper R-6. The composition is about
90 percent sodium and 80 percent carbonate plus bicarbonate, with the remain-
der of the anions evenly divided between sulfate and chloride. The dissolved
solids are relatively low, ranging from 700 mg/1 to 900 mg/1. The tempera-
ture is cooler than the rest of the Lower Aquifer, suggesting at least moder-
ate hydraulic conductivities.
A highly saline zone about 50 feet thick was encountered in well SG-17
at about 4940 feet (RBOSP, 1977b). This zone is characterized by sodium con-
tent greater than 90 percent and relatively high chloride content (25 to 40
percent), with the remainder carbonate plus bicarbonate. Total dissolved
solids are very high (20,000 to 40,000 mg/1). Water temperature is high, and
the extremely high TDS probably indicates a long residence time. The trans-
missivity may thus be moderate to low.
119
-------
Two wells, Cb-1 and SG-8, penetrate a similar interval but show radically
different water quality, with carbonate plus bicarbonate content above 90
percent, and much lower IDS levels than the chloride zone, ranging from 1200
to 2500 mg/1. Temperature is fairly high. This type of water probably ori-
ginates in some zone intermediate between the Lower Mahogany and the R-4,
perhaps the L-5.
Several wells, notably SG-1-1, SG-6-1 and SG-9-1, have water quality
compositions which seem to be some mixture of three zones. Dissolved solids
range from 1300 to 4000 mg/1 and composition is between that of the deep and
shallower zones, as is the temperature. One well is completely anomalous,
SG-10R. The extremely high chloride content of water from this well bears no
resemblance to any other water from the lower Mahogany Zone, or any other wa-
ter from Tract C-b, for that matter.
The general pattern of water quality distribution outlined above is con-
firmed by conductivity measurements of drilling water. The manner in which
this was determined by tract developers is unclear. The conductivity changes
with depth as shown in Figure 6-15. Above the Four Senators Zone, conductiv-
ity is greater than 1000 urohos per centimeter, while below the zone it is
less than 1000 umhos per centimeter. The lower Mahogany Zone conductivity
approximately equals 1000 umhos per centimeter and gradually increases to
about 1400 umhos per centimeter at the R-5. Below the R-5, it increases to
3000 umhos per centimeter.
Trace Constituents
The groundwater is rich in several trace elements. The most striking
example is fluoride, which is present in concentrations as high as 190 mg/1.
The mean for the Lower Aquifer is 21 mg/1 and for the Upper Aquifer is 10.
mg/1. This is far above the drinking water standard of 1.4 mg/1. Boron is
also exceedingly high in certain strata, reaching 400 mg/1 in the saline zone
below the L-4. The Lower Aquifer average is 36 mg/1 and the Upper Aquifer is
18 mg/1. Other trace elements which are considered high are aluminum, ar-
senic, copper, iron, manganese, and mercury. Other trace elements which are
higher than drinking water standards in some cases are calcium, chromium,
lead, nickel, selenium, silver, and zinc. Maximum, minimum, and mean values
of the trace elements for the various aquifers are summarized in Tables 6-2
and 6-3. In Table 6-4, these data are compared to water quality standards.
Water in some wells on the tract contains significant organic material.
This material takes the form of an oily liquid floating on the water surface,
and is apparently derived from the kerogen in rich oil shale beds, although
some organic contamination may occur from the swabbing equipment used for
sampling. In some cases, swabbing can stimulate production of this fluid.
An analysis of the liquid is presented in Table 6-5.
Summary
In summary, the aquifer system is highly stratified. Layers near the
Mahogany Zone contain largely sodium bicarbonate type waters and relatively
120
-------
WELL SG-19
rrmnhos 5
SO-6 AT-iA SG-IO
P »«? P*. "»
SG-21
P *
7000 —
> 6500-
4
UJ
O 6000-
CD
4
5500-
5000-
•Toj> Parachute Creek
Four Senator* Zone
"A" Aauitard
Bate A" Groove
Mine. Zone
Top " B Zone
" B" Aquitord
Lower Rich Zone
-70OO
-6SOO :
-6000 g
4
Z
g
—55OO j
—5000
WELL SG-9
TGTI-I
mmho, 25 33
SG-IO
U> Q
SO-11
T67I-2
SO-8
70OO—
6500—
60OO—
5500—
50OO—
4500—
4000 —
3500-
1111 ' ' ' '
Y
/
'l.....
Jp,
\
„*£,;„
%
>
TO 2750'
/
7
'¥""">
\
.JU^,.
i — i
JT
^f
/
v
•V""" •
V
?
f s.
TO 2211'
TD E550'
'
y^
£
!- — Base "A" Groove
jj/jfb Top "B ' Groove
*^^""BM Aqultetrd
^x
^W
Tn 9Afift'
ulch
Figure 6-15.
North-south and east-west strati graphic sections showing
specific conductance profiles in selected wells on Tract C-b
(C-b Shale Oil Venture, 1977b).
121
-------
TABLE 6-2. SUMMARY OF WATER QUALITY OF GROUNDWATERS OF TRACT C-b (C-b Shale Oil Venture, 1977b)
Concentration3
Alluvial wells
Number of
Constituent observations
Conductivity
PH
Total dissolved
sol i ds
Gross alpha
radiation
Gross beta
radiation
,_, Total organic
ro carbon
ro
Dissolved organic
carbon
Amrnon 1 a
Bicarbonate
Calcium
Carbonate
Chloride
Hydroxi de
Lithium
Magnesium
Nitrate
Phosphate
Potassium
Silica dioxide
Sodium
Sulfate
77
77
77
53
53
31
22
77
77
77
58
77
31
65
77
77
77
66
77
77
77
Minimum
950
7.3
696
0
0
1
2
<0.01
320
16
1
0.9
<0.1
.__
20
<0.02
<0.01
0.7
11
93
200
Maximum
1,930
8.7
1,300
18
13
9
11
15
730
102
23
29
1.7
<0.5
120
9.1
1.1
5
41
730
530
Mean
1,380
8.2
996
5
2
5
6
0.5
540
67
6,2
11
___
—
80
1.6
<0.5
1.5
17
175
370
Standard
deviation
220
0.3
158
4
4
3
2
1.8
90
21
5
7
—
—
18
2.0
0.1
o:e
4
86
83
Number of
observations
49
50
47
32
32
16
16
41
50
50
40
50
45
50
45
45
40
50
50
50
Springs and seeps
Minimum
840
7.3
547
0
0
1
2
0.01
320
28
<0.1
0.9
—
28
<0.02
<0.01
0.6
12
68
200
Maximum
1,560
8.5
1,130
20
30
6
10
0.4
650
160
7.2
18
<0.5
100
8.1
0.1
2.3
21
240
440
Mean
1,300
8.2
925
6
4
3
5
0.12
480
83
2.9
7.1
—
78
2.2
<.05
1.4
16
130
360
Standard
deviation
145
0.27
97
4
6
2
2
0.1
77
24
3.3
3.9
.„
18
2.5
0.04
0.5
3
28
66
(continued)
-------
TABLE 6-2 (continued)
ro
CO
Concentration
Upper Aquifer
Number of
Constituent observations
Conductivity
PH
Total dissolved
solids
Gross alpha
radiation
Gross beta
radiation
Total organic
carbon
Dissolved organic
carbon
Ammonia
Bicarbonate
Calcium
Carbonate
Chloride
Hydroxide
Lithiun
Magnesi urn
Nitrate
Phosphate
Potassium
Silica dioxide
Sodium
Sulfate
52
53
52
49
49
34
_„„
51
53
53
51
53
33
52
53
52
51
52
53
53
53
Minimum
800
8.1
520
0
0
1
-_«.
0.1
340
3
<1
2
—
—
2.2
<0.02
<0.1
0.3
4
44
4
Maximum
4,200
9.1
3,100
21
33
9
=*-«
7.9
2,100
120
76
510
<0.1
3.1
150
2.9
0.4
11
32
1,200
520
Mean
1,670
8.6
1,100
6
3
3
«.<._
1.2
790
32
21
26
—
___
42
0.41
<0.09
2.2
17
330
220
Lower Aquifer
Standard Number of
deviation observations Minimum
700
0.24
490
5
8
2
*«_
1.3
525
28
18
70
...
—
40
0.57
0.06
2.2
6
248
170
49
49
49
43
43
27
21
48
49
49
47
49
27
47
49
49
49
48
49
49
49
630
8.1
356
0
0
1
2
0.1
100
2
7
1
...
1.3
1.5
<0.02
0.01
1
2
140
2
Maximum
45,000
9.3
42,000
460
390
40
175
200
25,000
220
2,000
9,800
<0.1
79
110
3.4
0.7
120
38
17,000
350
Mean
7,240
8.7
6,190
28
16
10
23
17
4,000
14
220
1,200
...
10
11
0.46
<0.9
21
13
2,500
63
Standard
deviation
11,800
0.024
11,600
83
60
11
38
42
6,700
34
490
2,700
...
23
21
0.77
0.10
36
7
4,700
92
are in milligrams per liter, with the following exceptions:
(picocuries per liter)
conductivity (micromhos per centimeter); pH (pH units); radiation
-------
TABLE 6-3, SUMMARY OF TRACE ELEMENT LEVELS IN GROUNDWATERS OF TRACT C-b (C-b Shale Oil Venture, 1977b)
J—»
f\3
-fa
Concentration (mg/1)
Alluvial wells
Constituent
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
B romi ne
Cadmium
Cesium
Chromium
Cobal t
Copper
F 1 uor i de
Gallium
Germanium
Iodine
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Rubidium
Scandium
Selenium
Silver
Strontium
Titanium
Tungsten
Vanadium
Yttrium
Zinc
Zirconium
Number of
observations
47
—
70
50
8
50
50
5
28
49
41
50
77
23
6
43
77
50
77
41
41
48
50
50
21
—
76
47
—
50
13
50
30
Minimum
0,01
—
<0.001
0,01
ND
0.001
0.006
ND
ND
0.002
<0.001
0.005
0.1
ND
ND
0.001
<0.05
<0.002
0.003
0,00002
0.005
0.003
0.002
<0.001
ND
—
0.04
0.01
—
<0.001
ND
0.01
<0.001
Maximum
3
—
0.05
0,6
<0.002
<0.05
0.01
<0.03
0.03
<0.1
0.05
0.2
5
0.003
0.03
0.03
9
0.2
2.3
0.048
0.2
0.1
0.06
0.02
0.03
—
10
2
—
0.2
0.007
2
0.04
Mean
0,3
—
0.006
0.07
—
0.5
0.04
—
0.006
—
0.007
0.04
0.65
—
0,007
<0.3
0.02
0.2
0.003
0.04
0.02
0.01
0.004
O.OQ9
—
1.9
0.3
—
0.01
0.2
0.007
Standard
deviation
0.6
—
0.01
0.1
—
0.8
0.03
...
0.008
—
0.01
0,04
0,87
—
0.007
0.5
0.03
0.5
0.01
0.03
0.02
0.01
0.003
0.01
—
1.2
0.4
—
0.03
—
0.4
0.01
Number of
observations
33
4
45
34
5
37
34
5
16
34
30
34
50
15
3
26
49
35
33
40
27
33
29
34
14
1
49
34
7
34
5
34
19
Springs and seeps
Minimum
0.004
NDa
0.0005
0.01
ND
0.001
0.004
ND
<0.001
0.005
<0.001
0.003
0.1
ND
ND
<0.001
0.01
0.001
0.002
<0. 00003
<0.005
0.003
0.001
<0.001
ND
ND
0.6
0.02
ND
<0.001
ND
0.01
ND
Maximum
3
0.006
<0.05
0.1
0.002
1.6
0.08
<0.008
0.02
0.1
0.05
0.2
2.1
0.006
0.008
0.06
7.8
0.05
0.2
0.002
0.2
0.08
0.05
0.02
<0.04
<0.001
5
0.6
0.02
0.02
0.003
0.4
0.004
Mean
0.4
—
0.005
0.04
—
0.4
0.02
—
—
0.007
0.04
0.45
___
—
0.005
<0.4
0.02
0.03
0.0004
0.03
0.02
0.01
0.005
—
—
2.0
0.2
—
0.005
—
0.08
0.005
Standard
deviation
0.6
—
0.01
0.02
—
0.5
0.02
—
—
0.01
0.05
0.40
—
0.01
1.2
0.02
0.04
0.0005
0.04
0.02
0.01
0.004
—
—
1.0
0.2
—
0.004
—
0.08
0.009
(continued)
-------
TABLE 6-3 (continued)
ro
CJI
Concentration (mg/1)
Upper Aquifer
Constituent
Aluminum
Antimony
Arsenic
Barium
Beryl 1 i urn
Boron
Bromi ne
Cadmium
Cesi urn
Chromi urn
Cobal t.
Copper
Fluoride
Gallium
Germanium
Iodine
Iron
Lead
Manganese
Mercury
Molybdenun
Nickel
Rubidium
Scandium
Selenium
Silver
Strontiun
Thorium
Titanium
Tungsten
Uranium
Vanadium
Yttrium
Zinc
Zirconium
Number of
observations
48
11
53
51
14
52
52
9
40
50
43
52
53
33
8
46
53
52
53
49
47
50
50
51
33
12
51
4
52
8
13
51
4
52
28
Minimum
0.003
ND
<0.001
0.009
ND
0.01
0.003
ND
<0.001
0.002
<0.001
0.003
0.1
<0.001
ND
<0.001
<0.02
<0.002
0.002
<0. 00003
0.003
<0.001
<0.002
<0.001
<0.001
ND
0.1
ND
0.003
ND
ND
<0.001
ND
0.003
<0.001
Maximum
4
0.02
0.06
0.6
0.003
18
0.2
<0.02
0.2
0.3
0.01
3
190
0.004
0.002
0.08
7
0.07
0.6
0.0031
0.1
0.2
0.05
0.009
0.03
0,05
17
<0,001
2
0.02
0.03
0.006
0.01
2
0.03
Mean
0.3
—
0.01
0.1
—
1.4
0.03
—
0.01
0.003
0.09
10
...
—
0.006
0.5
0.01
0.1
0.0004
0.02
0.02
0.02
0.003
0.006
—
2.4
0.1
—
0.002
—
0.2
0.006
Standard
deviation
0.7
—
0.01
0.1
—
2.6
0.04
—
0.03
—
0.003
0.4
26
—
—
0.01
1.2
0.01
0.1
0.0008
0.02
0.03
0.01
0.002
0.026
2.6
—
0.3
___
-__
0.001
—
0.4
0.009
Number of
observations
45
24
48
47
18
44
45
4
46
47
43
46
49
37
15
45
49
47
48
44
42
30
47
47
23
9
49
1
47
13
10
47
19
45
36
Lower Aquifer
Minimum
0.002
ND
0.001
0.02
ND
6.05
0.003
ND
<0.001
0.002
<0.001
0.003
4
<0.001
ND
<0.001
<0.05
0.003
0.002
<0. 00003
<0.004
<0.001
0.005
<0.001
<0.001
ND
0.1
ND
0.006
ND
ND
<0.001
<0.001
0.005
O.001
Maximum
2
0.08
0.2
8
0.002
400
10
0.1
4
0.2
0.03
0.9
48
0.06
0.05
3
8
0.4
0.6
0.0027
0.2
0.06
0.9
0.01
0.02
0.02
10
<0.001
1
0.05
0.02
0.1
0.03
4
0.9
Mean
0.3
—
0.02
0.8
—
36
0.7
—
0.2
<0.009
0.006
0.06
21
0.007
...
0.3
0.8
0.03
0.1
0.000
0.04
0.01
0.07
0.004
0.004
—
1.3
—
0.1
—
___
0.01
0.2
0.008
Standard
deviation
0.4
—
0.03
1.7
—
100
2.1
—
0.8
0.004
0.007
0.14
10
0.01
—
0.7
1.8
0.06
0.09
0.0007
0.04
0.01
0.2
0.003
0.004
—
2.1
—
0.2
—
___
0.02
—
0,6
0.2
2ND - Not detected
-------
TABLE 6-4. COMPARISON OF TRACT C-b UPPER AND LOWER AQUIFER WATER QUALITY WITH COLORADO WATER
QUALITY STANDARDS (C-b Shale Oil Venture, 1977b).
Concentration (mg/1)a
Constituent
Aluminum
Ammonia
Arsenic
Boron
Cadmium
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Manganese
Mercury
Nickel
Radiation, alpha
Selenium
Silver
Zinc
Most
Restrictive
Standard
0.1
0.5
0.01
0.75
0.01
250
0.05
0.04
1.4
0.3
0.03
0.05
0.00005
0.1
15
0.01
0.00025
0.6
Mean,
Lower
Aquifer
0.3
17
0.02
36
—
1,200
—
0.006
21
0.8
0.1
0.1
0.0004
0.01
28
0.004
—
0.2
Maximum,
Lower
Aquifer
2.0
200
0.2
400
0.1
9,800
0.02
0.9
48
8.0
0.4
0.6
0.0027
0.06
460
0.02
0.02
4.0
Mean,
Upper
Aquifer
0.3
1.2
0.01
1.4
—
26
—
0.009
10
0.4
0.01
0.1
0.0004
0.02
6
0.006
—
0.2
Maximum,
Upper
Aquifer
4.0
7.9
0.06
18
0.02
53
0.3
3.0
190
7.0
0.07
0.6
0.0031
0.2
21
0.03
0.05
2.0
aExcept radiation, for which units are picocuries per liter.
-------
TABLE 6-5. RESULTS OF ORGANIC FRACTIONATION ANALYSIS OF WATERS
NEAR TRACT C-b (C-b Shale Oil Venture, 1977b).
Percent of
Sample source
Well A-l
Well A-3
Well A-6
Well A-7
Stewart Creek
Willow Creek
Upper Piceance
Creek
Lower Piceance
Creek
Spring S-3
Spring S-9
Snow at C-b-2
Snow at SG-18
Well SG-6-1
Well SG-6-2
Well SG-6-3
Well SG-8R
Well SG-10R
Well SG-20
Total
DOC,
(mg/1)
3.8
1.8
3.5
2.6
16.1
3.2
4.5
5.1
2.5
1.6
2.8
2.0
3.8
3.1
1.7
3.5
5.1
2.6
Hydrophobics
Aci ds
49
44
40
23
6
38
40
35
32
56
18
20
32
26
24
20
45
54
Neutrals
7
28
23
35
13
3
9
18
16
6
11
5
16
32
0
26
27
12
Bases
8*
0
6*
8*
0
0
0
0
8*
0
0
5*
29*
16*
24*
9*
6*
27*
total DOC
Hydrophilics
Acids
36**
28*
31**
35**
9
34
20
31
44**
38**
71*
70**
24**
35**
71**
46**
22**
8**
Neutrals
36**
28*
31**
35**
72
12
20
10
44**
38**
71*
70**
24**
35**
71**
46**
22**
8**
Bases
8
0
6*
8*
0
12
11
6
8*
0
0
5*
29*
16*
24*
9*
6*
27*
*,** indicates combined total for fractions shown.
127
-------
high hydraulic conductivity. Above the Mahogany Zone, dissolved solids, cal-
cium, magnesium, and sulfate content are all higher. Deep in the Lower Aqui-
fer are highly saline zones with extremely high dissolved solids, sodium, and
chloride. Between are moderate to low hydraulic conductivity zones with
largely sodium bicarbonate water.
Very little can be stated about area! distribution of water quality par-
ameters within the aquifers due to the erratic spacing of open intervals.
This spacing also severely limits the accurate determination of water quality
within most of the individual strata. The confusion is compounded by the
mislabeling of wells SG-19 and SG-20 as Upper Aquifer wells.
128
-------
SECTION 7
POTENTIAL POLLUTANT MOBILITY
INTRODUCTION
The purpose of this section is to evaluate the potential mobility of
pollutants (retort water and spent shale leachate-) from MIS retorts. The
general features of mobility of potential pollutants associated with surface
operation and disposal sites are considered in a companion report (Slawson,
1979) and will not be repeated here.
The consideration of potential pollutant mobility in the subsurface may
include evaluation of infiltration at the land surface, mobility in the va-
dose or unsaturated zone, and mobility in the saturated zone. Because of the
above-stated focus of this discussion, and the location of the retorts within
or adjacent to saturated zones, consideration of infiltration and vadose zone
mobility will not be included here.
GROUNDWATER FLOW
The mobility of potential pollutants from in-situ retorts depends upon
the characteristics of groundwater flow in the retort zone after retorting is
completed. Such flow may be in fractures, in porous media, or in solution
cavities. Flow through alluvium, rubblized oil shale, or in-situ spent shale
will generally be considered as flow through a porous media. Flow in the
aquifers of the Uinta Formation or Green River Formation will generally be
considered as flow through fractures or solution openings. In general, far
less attenuation due to sorptive processes will occur if flow is through so-
lution openings or fractures than for flow through porous media. However,
considerable dispersion and diffusion due to physical processes is possible,
and interaction between leachates and natural groundwaters and certain bio-
logical processes can occur. For flow through porous media, substantial
attenuation may occur for some pollutants, particularly where clays, metal
oxides, or organic matter are associated with the medium.
Hydrogeologic Modifications
During development and operation of in-situ retorts, hydrogeologic con-
ditions of the retort fields will be substantially altered. Such alteration
will govern groundwater flow after retort abandonment and the release and mo-
bility of potential pollutants from in-situ retorts. Major characteristics
of in-situ operations related to the modification of the hydrogeology of the
mining site and release of potential pollutants include:
129
-------
& Dewatering of the retort zone and the resultant alteration of
the hydraulic regime will be required at many sites.
* Mining and rubblizing the retort, which will be in the Mahogany
Zone, may locally breach much, if not all, of the confining bed.
• Within the retorts, two forms of porosity and permeability will
exist, the porosity and permeability of discrete solid oil shale
rubble blocks and the porosity and permeability of the space
within the oil shale rubble. The former will importantly affect
the leaching of contaminants and the latter will control the
rate of water flow through the retort.
• The mining and retorting will, to an unknown extent, probably
immediately affect the porosity and permeability of rocks adja-
cent to the retorts as a result of the stresses caused by blast-
ing and burning. In the longer term, sloughing and collapse of
retort walls may occur and the retort roofs may stope upward,
perhaps eventually reaching the surface, although the extent of
surface disturbance is uncertain. Subsidence accompanying such
events may further alter subsurface flow patterns.
Influence of Dewatering
Dewatering. operations and the termination of dewatering will influence
groundwater flow in and adjacent to the retort zone. For example, consider
MIS retorts located generally within and below the various units of the Upper
Aquifer, perhaps extending to the upper units of the Lower Aquifer. Dewater-
ing is required to allow mining and retorting. As dewatering progresses and
the potentiometric surface is lowered in a particular area, the aquifers will
gradually be changed to unconfined aquifers and will be dewatered. At some
lateral distance from the area of dewatering, the aquifers will still be con-
fined; that is, the hydraulic head will be above the top of the aquifer.
•During dewatering, hydraulic heads in certain units of perhaps the Upper
and Lower Aquifer will be lowered by pumping. Head levels, in adjacent aqui-
fer units may also be affected indirectly by vertical leakage into the pumped
interval. For example, dewatering in the Upper Aquifer may locally produce
flow upward from the Lower Aquifer into the Upper Aquifer. As another exam-
ple [using Upper Aquifer units UPC^ and UPC? defined for Tract C-b (see Figure
9-6)j, if UPC2 is dewatered, downward flow from UPCj into the mine and retort
zone may be induced. By the time dewatering is terminated, substantial mine
inflow of water may occur.
When dewatering ceases, water may enter the abandoned retort zone from
both lateral inflow and upward flow of groundwater from the Lower Aquifer.
Water will enter from lateral inflow of groundwater from the Upper Aquifer
and possibly from upward flow of water from the Lower Aquifer which, at least
temporarily, will have a head level above that of the Upper Aquifer.
130
-------
MOBILITY AND ATTENUATION FACTORS
Influence of Retorting Conditions
Experimental studies show that organic chemicals which are water soluble
result from retorting and may be transported by groundwater (Amy, 1978). The
inorganic chemistry of the retorted oil shale will also definitely be altered;
however, the manner in which the inorganic chemistry of circulating ground-
water will be changed by contact with the retorted shale is not yet clear.
Retorting conditions (e.g., with temperatures of 500° to 1200°C) will
have an important influence on the constituents which are mobile. Under the
conditions expected in an in- situ oil shale retort, several types of reactions
can take place.
First, alkali earth (calcium, magnesium) carbonates can calcine in the
range 500° to 800° C, for example:
CaC03 •»• CaO + C02 (1)
Waters exposed to such materials will be highly basic, because of the
reaction:
CaO + H20 •»• Ca++ + 20H~ (2)
In addition, concentrations of HCOZ will decrease compared to natural
groundwaters.
Organic materials may be partially or entirely oxidized during retorting,
producing a wide range of species:
H20 + 02 + HC, N, S •*• C02, NOX, S02, S04 (oxidation) (3)
+ hydrocarbons, R-NH2, R-C02,
reduced polynuclear aromatics (pyrolysis) (4)
NH3, H2S
+ SCN", S20j, S40g, CN" (mixed) (5)
The production of reduced species would be enhanced by incomplete combustion
in the retort.
Normal decomposition process can also be hastened due to the fracturing
and heat:
B203 + 60H" -» 280^' + 3H20 (6)
The latter reaction would be encouraged in basic conditions.
131
-------
Transition metals with multiple oxidation states may be oxidized:
80H" 302 + 2Mo203 * 4MoO^ + 8H20 (7)
80H" + 302 + 2C^2°3 * 4Cr°4 + 8H2°
The reactions in Equations 7_and 8 are aided by alkaline_conditions, the
solubility properties of both MoO^ and CrO^ are similar to $04 .
Chalcogenic elements may be oxidized to the more soluble oxides:
MoS2 + 302 •»• Mo02 + 2S02 (9)
Although the mineral form of most trace elements in oil shale has not
been established, Desborough et al. (1976) suggest that cobalt, nickel, cop-
per, zinc, and possibly arsenic, selenium, molybdenum, and cadmium exist as
the pyrite. Finally, sintering may occur during retorting, which would ren-
der the spent retort less permeable to groundwaters. Similarly, Smith et al.
(1978) also have seen the formation of insoluble calcium and magnesium
alumi no- silicates during the simulated in-situ retorting of oil shale, and
argued that such reactions would help insolubilize the spent shale.
Site-Specific Features
The following discussion outlines some of the features of proposed MIS
developments which will influence the potential for impact of pollution
sources on groundwater. The uncertainties noted in Sections 5 and 6 preclude
a detailed assessment of mobility at this time.
One key factor affecting potential groundwater quality impact is the lo-
cation of the MIS retort zone relative to aquifers. On Tract C-a, the retort
zone was originally defined as follows (Figures 7-1 and 7-2; RBOSP, 1977a):
Retort
number Interval
1-4 Mahogany Marker down through middle
B-groove into top of R-6 zone
5 A-groove downward to bottom of L-5 zone
6+ Top of R-8 zone to bottom of R-4 zone
On Tract C-b, the retort zone is defined as follows (Figure 7-3):
132
-------
SOUTHWEST
NORTHEAST
2
LLJ
7000 [— BOX ELDER
GULCH
CE 705A
6600
6200
5800
5400
5200 L-
CORRALGULCH
CE 702
UINTA
FORMATION
L8
R-8
A-GROOVE
MAHOGANY ZONE
B-GROOVE
R-6
L-5
R-5
GREEN RIVER
FORMATION
R-4
L-3
R-3
R2
R1
RO
L1
LOO
Figure 7-1. Approximate location of Tract C-a retort zone
in geologic cross section.
G-S13
BOX ELDER
GULCH
CORRAL
GULCH
IN SITU
RETORT
ZONE
UPPER AQUIFER ZONE
A-GROOVE
B-GROOVE
BLUE MARKER
ORANGE MARKER
U UPPER AQUIFER HEAD LEVEL
L LOWER AQUIFER HEAD LEVEL
LOWER AQUIFER ZONE
Figure 7-2.
Tract C-a in-situ retort
geologic cross section.
zone in relation to
133
-------
oo
7200
7000
6800
6600
6400
6200
Z. 6000
tu
U
fc 5800
D
5600
5400
5200
5000
4800
4600 L-
NORTH
SOUTH
VERTICAL EXAGGERATION 8:1
LEGEND
AQUIFER
AQUITARD
ALLUVIUM
UPPER AQUIFER
POTENTIQMETRIC LEVEL |
LOWER AQUIFER >
POTENTIOMETRIC LEVEL g
3;
I
O
BLACK SULFUR TONGUE Z
THIRTEEN MILE
CREEK TONGUE
FOUR SENATORS ZONE
MAHOGANY ZONE
COMMERCIAL RETORT ZONE
:iiSiiivi R G
L-5ZONE
UPPER HALF R-5ZONE
R-5ZONE
1/2
DISTANCE (miles)
Ci
3]
m
5
Figure 7-3. Approximate location of Tract C-b retort zone in geologic cross section.
-------
Mine or retort
element Interval
Upper air level Above the A-groove (above top of Mahogany Zone)
Retorts Top of Mahogany Zone through top two-thirds of
R-6 zone
Lower produc- Within L-5 zone
tion level
Figures 7-1 through 7-3 also indicate the potentiometric levels in the
Upper and Lower Aquifers on Tract C-a and C-b, respectively, relative to the
in-situ retorting zone. From these figures, there is obviously sufficient
head in the Lower Aquifer to allow flow into the retort zone. However, flow
into the Upper Aquifer zone will be controlled by the head of the Upper Aqui-
fer and the occurrence of an interconnection between the retorts and the Upper
Aquifer. Under existing head conditions, flow into the Upper Aquifer would,
in general, not be expected except at locations such as the northeast corner
of Tract C-a, where the Lower Aquifer head exceeds that of the Upper Aquifer.
With existing head conditions generally observed on Tracts C-a and C-b, the
interconnection of Upper and Lower Aquifers via abandoned in-situ retorts
would result in movement of leachates into the Lower Aquifer. This assumes
that existing head conditions would recur and is dependent somewhat on which
aquifer reached equilibrium first after dewatering was terminated. Subsequent
discharge of leachate to surface streams (such as Yellow Creek or Piceance
Creek) may then occur through existing Lower Aquifer discharge points at some
location(s) off tract.
Flow paths in the Upper Aquifer beneath Tracts C-a and C-b are shown in •
Figures 7-4 and 7-5, respectively. These are anisotropic flow nets presented
in Section 5 (Hydrogeologic Framework). Difficulties arose in developing
flow nets for the Lower Aquifer (see Section 5).
Retort Water Constituents
The major inorganic chemical constituents of retort water are presented
in Section 3. The predominant cations would probably be sodium and ammonium.
The major anions would probably be inorganic carbon forms, sulfur forms, and
chloride. Of these constituents, sodium and chloride would be highly mobile.
Ammonium would not generally be mobile, but it could easily be converted to
nitrate and be highly mobile. However, some nitrate could subsequently.be
denitrified under reducing conditions and removed from solution by sulfate
reduction. Both of these forms are thus classified as moderately mobile.
High salinity would be a major concern. Total dissolved solids or salinity
is generally considered to be mobile, because many-of the major constituents
are moderately or highly mobile.
Trace elements of concern include fluoride, boron, molybdenum, and pos-
sibly arsenic and barium. In general, boron and molybdenum are moderately
mobile. The mobility of fluoride is controlled primarily by solubility of
fluorite, and thus by the calcium content. Fluoride is also more mobile at
135
-------
PROCESSED SHALE
DISPOSAL PILE
CRUSHED
DEVELOPMENT
ORE DISPOSAL
DISTANCE (miles',
Figure 7-4. Anise-tropic flow net of Upper Aquifer superimposed
on Tract C-a plot plan.
136
-------
SG204
•SGI 9
DIRECTION OF MAXIMUM
PERMEABILITY
1 INITIAL IN SITU RETORT FIELD
2 MINE SUPPORT AND ACCESS
3 MINED ROCK AND RAW SHALE DISPOSAL.
corroNwooo GULCH
4 COTTONWOOD IMPOUNDMENT DAM
5 OIL STORAGE
6 WASTEWATER POND
7 STACKS
8 OIL TREATMENT
9 GAS TREATMENT
10 SORGHUM GULCH
11 IMPOUNDMENT DAM
iSG-8
SG18A
KEY TO WELLS
• UPPER AQUIFER
• LOWER AQUIFER
A DUAL COMPLETIONS
Figure 7-5. Anisotropic flow net of Upper Aquifer superimposed on
Tract C-b initial development plot plan.
high pH values. For purposes of this report, fluoride is classified as mod-
erately mobile. However, it could be highly mobile at low calcium contents.
The mobility of barium is limited by high sulfate contents, and it would thus
be of low mobility. The mobility of arsenic is low except under reducing
conditions. For purposes of this report, arsenic is classified as moderately
mobile.
Organic chemical constituents of concern include organic carbon forms,
organic nitrogen (and perhaps sulfur) forms, oil and grease, phenols, and
possibly cyanide. The mobility of organic carbon forms in groundwater is
poorly known; however, analyses for dissolved organic carbon content of
groundwater from the Lower Aquifer at Tract C-b indicate that significant
amounts are present in groundwater under natural conditions. Thus, the mo-
bility of organic carbon forms ,is ranked moderate. The mobility of organic
nitrogen forms in groundwater is not well known. However, it is expected
that conversion to nitrate could easily occur, and this nitrogen form would
be highly mobile. Some nitrate could subsequently be denitrified under re-
ducing conditions and lost from the groundwater system. Thus, the mobility
137
-------
of organic nitrogen is ranked as moderate. Oil and grease are of low mobil-
ity in most granular, porous media, but could be of much higher mobility in
the fracture or solution-cavity aquifer systems. The mobility of phenols and
cyanide in groundwater is poorly known. Attenuation mechanisms include ad-
sorption and biodegradation. However, the mobility of cyanide in aerobic
situations is classified as high. The mobility of these constituents is
ranked as moderate to high.
Spent Shale LeachateConstituents
Likely constituents and their concentrations in leachate from in-situ
spent shale are discussed in Section 3. It should be noted that this infor-
mation comes from surface retorted and simulated in-situ retorted materials.
The major cation would be sodium and the major anions would be inorganic car-
bon forms and sulfate. The mobility of these constituents has been discussed
in the previous section. Total dissolved solids or salinity is generally
considered to be mobile, because many of the major constituents are moder-
ately or highly mobile.
Chappel (1978) discussed trace elements of concern. Studies at the
University of Colorado have focused on arsenic, boron, fluoride, molybdenum,
and selenium. These trace elements were selected on the basis of their oc-*
currence in oil shale, the likelihood of mobilization by processing, and the
likelihood that they could cause serious effects. These studies showed that
there was little selenium or arsenic in leachate from spent shale, but there
were high contents of fluoride, boron, and molybdenum. Chromium has been
found in moderate concentrations in the leachate. The primary attenuation
mechanism for boron is adsorption, primarily by iron and aluminum oxides. At
high pH values, such as occur in leachate from spent shale, fluoride, chromium
and molybdenum, are generally mobile. Molybdenum is not highly soluble at
low or moderate pH values in groundwater. Thus, fluoride, boron, and molyb-
denum are ranked as moderately mobile. Chromium is also ranked as moderately
mobile.
Organic chemical constituents, as measured by total organic carbon, are
present in significant concentrations in leachate from spent oil shale. The
mobility of organic carbon forms was discussed above.
Constituents in Dewatering and Mine Hater
In general, the chemical quality of water in the alluvium and from
springs and seeps is similar. Water in the Upper Aquifer (at Tract C-b—UPCj,
and UPC£ combined) is of somewhat higher salinity than groundwater in the al-
luvium. Contents of sodium and bicarbonate are higher, and fluoride contents
are markedly higher, in the Upper Aquifer than in the alluvium. Water in the
Lower Aquifer (LPC3 and LPC^) is locally of much higher salinity than water
in the Upper Aquifer. Sodium, chloride, bicarbonate, boron, and fluoride
contents are markedly higher in the Lower Aquifer. Further delineation of
the vertical variation in groundwater quality may be possible after the re-
completions of many of the monitor wells, as now proposed.
138
-------
There are two primary potential impacts that can be considered. The
first is when water from the Upper Aquifer is disposed in a manner that can
affect groundwater in the alluvium or water issuing from springs or seeps.
In this case, sodium, bicarbonate, and fluoride could be considered potential
pollutants. The mobility of these constituents has been previously discussed.
Total dissolved solids would be considered to be of moderate mobility because
most of the major constituents are moderately or highly mobile. The second
situation is when water from the Lower Aquifer is disposed in a manner that
can affect groundwater in the alluvium, water issuing from springs or seeps,
or water in the Upper Aquifer. In this case, sodium, bicarbonate, chloride,
fluoride, boron, and dissolved organic carbon could be considered potential
pollutants. The mobility of these constituents has been discussed above.
MODELS OF POTENTIAL POLLUTANT MOBILITY
From the preceding discussions, it is apparent that one can draw from
available information on the composition of oil shale retorting byproducts;
on general knowledge of physical, chemical, and biological processes; and on
hydrogeologic data on the oil shale region to develop a description of the
potential leaching, mobility, and attenuation of constituents from MIS re-
torts. It is also apparent that this description is very qualitative. This
results from the many factors which are uncertain or unknown with regard to:
* Leaching phenomena in MIS retorts
* Complexities of the hydrodynamics of these groundwater systems
in response to MIS development
• Influence of various attenuation mechanisms within the retort
zone and elsewhere in the aquifers which may be affected by MIS
development.
One approach for examining the mobility of constituents of retort water
and spent shale leachate from in-situ retorts is mathematical modeling. How-
ever, because of the complexities of the existing hydrogeologic system (see
Sections 5 and 6) and the additional uncertainties created by the proposed
hydrogeologic modifications, (1) only very simplified models can reasonably
be formulated, and (2) probably numerous models could be formulated, produc-
ing a wide spectrum of results. In addition, no data exist for validation of
the models, descriptions, and predictions of the hydrodynamic and water qual-
ity processes of concern. Even with these serious limitations, models may
still provide some useful information, but the limitations should always be
considered in the use of the model results.
Several modeling efforts are summarized in Appendix A of this report.
These efforts address relatively small-scale (a few miles) events, rather
than events on a regional scale. The former approach seems more appropriate
for source-specific monitoring design. These model summaries are not intended
to be an all-inclusive set of available models and this listing should be up-
dated as this program progresses.
139
-------
These analyses are admittedly simplistic and numerous questions may be
raised about the realism of the estimates of concentration, transport times,
and attenuation processes. However, several general conclusions can be drawn
from these modeling studies:
• Under certain hydrogeologic conditions (resulting from site-
specific predevelopment conditions and modifications in the
hydrogeologic framework (e.g., from dewatering and rubbling of
in-situ retorts)), interaction between abandoned retorts and
groundwater systems is likely
• Leaching of significant amounts of soluble materials is likely
from some in-situ operations
• Appreciable decline in groundwater quality can result from in-
situ oil shale development
• The impacts on groundwater quality may take several years to oc-
cur and have a very long duration (several decades or centuries).
The models provide some quantification of these items. Because of the num-
erous unknowns and complexities of this physical system, estimation of rea-
sonable bounds on the problem may be adequate for monitoring design and
evaluation purposes.
In addition, consideration of these model constructs and the assumptions
inherent in the mathematical solutions provides an avenue for defining the
present state of our understanding of the rather central issue of potential
pollutant mobility. By defining the unknown quantities, identifying inade-
quate or inappropriate assumptions, and by attempting to describe extremely
complex phenomena in precise mathematical form, the direction of future re-
search is developed and plans can be formulated to develop data to deal with
these difficulties.
From such considerations, the following issues have been noted:
• Model formulations addressing flow as being through porous media
are not appropriate for addressing MIS development
• Significant uncertainties exist with regard to the leaching of
MIS retorts (assuming interconnection with aquifers)
— Variation over time (several pore volumes)
~ Concentrations of various constituents
— Total mass leaching which may occur
-- Leaching rates
140
-------
— Potential influence of attenuation mechanisms within the
retort zone (precipitation, sorption, ion exchange,
biological activity)
— The hydraulic properties of MIS retorts
• Significant uncertainties exist with regard to movement of con-
stituents leached from MIS retorts
— Hydraulic considerations
* Aquifer interconnection
• Differential response of aquifers after dewatering is
stopped
• Leakage between aquifers
• Direction and rate of flow
— Attenuation mechanisms
• Influence of dispersion processes
• Influence of precipitation and biological processes
* Influence of sorption processes.
These items then become aspects for further data collection, data evaluation,
and other research activities pursued to allow one to develop a better model
of the impact of MIS retorts on groundwater quality. The term "model" is
used here in a broad sense and is not limited to mathematical constructs, but
also includes structured evaluation schemes, such as the monitoring design
guidelines to be developed by this research project.
141
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SECTION 8
PRELIMINARY PRIORITY RANKING OF
POTENTIAL POLLUTION SOURCES
In the preceding Sections, potential sources of impact on groundwater
quality have been identified and characterized using proposed developments on
Tracts C-a and C-b as the study case. The hydrogeologic framework and ground-
water quality of the study area are described in Sections 5 and 6, respec-
tively. Potential pollutant mobility from in-situ retorts is discussed in
Section 7 and from surface facilities is presented elsewhere (Slawson, 1979).
These descriptive and evaluative steps provide a basis for developing a pre-
liminary priority ranking of potential pollution sources. Decisions with
regard to monitoring design cost effectiveness are based on such a priority
ranking.
Three basic criteria have been used to develop this source-pollutant
ranking. The first criterion ranks these items relative to volume of waste,
persistence, toxicity, and concentration. Certainly the source with the
largest waste volume, with pollutants of longest persistence, highest toxic-
ity and highest concentration, will receive (all other factors being equal)
the highest priority for monitoring.
The second ranking criterion is based on the mobility of pollutants.
Mobility is a function of method of disposal, waste loading, and sorptive and
chemical interactions. The most mobile pollutants will receive a high rank-
ing or priority for monitoring.
The third criterion in the ranking scheme addresses the known or antici-
pated harm to water use. This is a function of the existing or potential
type and magnitude of various water uses and the concentration changes which
may result from groundwater pollution.
Data from the preceding sections of this report are summarized in Table
8-1. These data have been used for development of the priority ranking, as
follows:
142
-------
TABLE 8-1. SUMMARY TABLE OF DATA AND ASSESSMENTS FOR POTENTIAL POLLUTION SOURCES ASSOCIATED WITH
IN-SITU OIL SHALE DEVELOPMENT
OJ
Amount of waste3
Potential pollution
source or cause Tract C-a Tract C-b
Waste rock and/ or 36,000 TPD 41,000 TPD
raw oil shale (100,000 tons
storage)
Pewatering and 25 cfs 4 cfs
mine water
Retort water 57,000 8PSO 27,000 BPSD
Potential pollutants
See Processed Shaleb
Upper Aquifer:c
TDS
Calcium
Magnesium
Potassium
Sulfate
Chloride
Fluoride
Boron
Bicarbonate
Carbonate
Lithium
Lower Aquifer:
TDS
Sodium.
Calcium
Magnesium
Potassium
Sulfate
Chloride
Fluoride
Boron
Bicarbonate
Carbonate
Lithium
Major inorganics:*1
TDS
Conductivity
PH
Alkalinity
Sulfate
Thiosulfate
NH3-N
NHJ-N
Chloride
Sodium
Fluoride
Organics:
DOC
Organic N
Phenol s
Cyanide
(possible concentration)
Potential pollutant mobility
Relative rates for various constituents
probably similar as for shale; however,
absolute rates lower due to surface
rather than in-situ disposal; also pro-
cessed shale more Teachable
Major inorganic ions (e.g., sodium and
(3,100 mg/1) chloride) measured by salinity highly
(1,200 mg/1) mobile. Some ions, such as bicarbo-
(150 mg/1) nates, fluoride, boron, DOC moderately
(10 mg/1) mobile
(520 mg/1)
(510 mg/1
(190 mg/1)
(20 mg/1)
(2,100 mg/1)
(80 mg/1)
(150 mg/1)
(42,000 mg/1)
(17,000 mg/1)
(220 mg/1)
(110 mg/1)
120 mg/1)
(350 mg/1)
(9,800 mg/1)
(50 mg/1)
(400 mg/1)
(25,000 mg/1
(2,000 mg/1
(110 mg/1)
Major inorganic ions (e.g., sodium,
(14,000 mg/1) chloride, ammonia) highly mobile.
(21,000 pmhos/cm) Inorganic carbon and sulfur species and
(9)
fluoride of more moderate mobility due
(16,000 rog/1) to precipitation and other attenuating
(2,000 mg/1
mechanisms. Trace constituents such as
(2,700 mg/1) boron, arsenic, and molybdenum, of mod-
(3,800 mg/1) erate mobility. Other trace constitu-
(3,500 mg/1) ents (e.g., barium) are of low mobility.
(750 mg/1) Mobility of organic species largely
(4,300 wg/1) uncertain; assumed to be moderate for
(60 mg/1) this analysis.
(1,000 mg/1
(630 mg/1
(60 mg/1
(1 mg/1
(continued)
-------
TABLE 8-1 (continued)
Potential pollution
source or cause
Retort water
(continued)
Processed shale:
In- situ
(leachate)
Surface disposal
(leachate)
Amount of waste
Tract C-a Tract C-b Potential pollutants (possible concentration)
Trace elements:
Arsenic
Barium
Boron
Bromi de
Iron
Molybdenum
Selenium
9.8 to 14.4 x 1.5 to 2.2 x Major inorganics:6
10» tons 10§ tons TOS
(total) (total) pH
Bicarbonate
Carbonate
Sulfate
Nitrate
Chloride
Fluoride
Calcium
Magnesium
Sodium
Potassium
Boron
TOC:
36,000 TPD None Major inorganics:f
TDS
Sodium
Calcium
Magnesium
Potassium
Sulfate
Chloride
Fluoride
Organics:
Phenol ics
TOC
Benezene extractables (POM,
Carcinogens
Trace elements:
Mercury
Lead
Cadmium
Arsenic
Copper
Zinc
Selenium
Iron
Boron
(1 mg/1)
(1 mg/1)
(30 mg/1)
(2 mg/1)
(1 mg/1)
(0.5 mg/1)
(0.2 mg/1)
Potential pollutant mobility
Major Inorganics (e.g., sodium) as
(30,000 mg/1)
(9)
(9,800 mg/1)
(2,000 mg/1)
(4,800 mg/1)
(5 mg/1)
(4',300 mg/1)
(50 mg/1)
(60 mg/1)
(230 mg/1)
(8,900 mg/1)
(35 mg/1)
(>40 mg/1)
(40 mg/1)
(140,000 mg/1)
(35,000 mg/1)
(3,000 mg/1)
(4,700 mg/1)
(600 mg/1 )
(90,000 mg/1 )
(3,000 mg/1)
(20 mg/1)
Unknown
(3-5 w/o)
PAH) (2,500 ppm possibly)
Unknown
(0.005 mg/1)
(0.004 mg/1)
(0.006 mg/1)
(0.2 mg/1)
(0.2 mg/1)
(3 mg/1)
(2 mg/1)
(2 mg/1)
(10 mg/1)
measured by TDS highly mobile. Mobility
of inorganic sulfur and carbon species
and fluoride may be moderated
by precip-
itation reactions. Trace constituents
(e.g., chromium, molybdenum,
of moderate mobility. Other
ments probably low mobility.
of organics uncertain.
See Slawson (1979)
and boron)
trace ele-
Mobility
(continued)
-------
TABLE 8-1 (continued)
Amount of waste
en
Potential pollution
source or cause
Tract C-a
Tract C-b
Potential pollutants (possible concentration)
Potential pollutant mobility
Oily water
Foul water
stripping
Raw water
treatment
Cooling water
blowdown
Sanitary waste water
Oil treatment and
upgradi ng
Sulfur recovery
process
Catalysts for
sulfur recovery
Tankage:
Shale oil
Naphtha
Heavy oil
Sas oil
Fuel oil
Ammonium-nitrate
Runoff
Disturbed areas
Explosives
Water Water
•/•57.000 BPSO ^7,000 BPSD
Uncertain, see oily water
treatment
Sludge 870 TPY Uncertain
Zeolites 3 TPY
Uncertain 100 gpnt
Uncertain Uncertain
No on- site upgrading except
addition of flow-enhancing
agents
265 TDPD 92.2 LTPO
52 TPY Uncertain
50,000 bbl Uncertain
70,000 bbl
140,000 bbl
1,000 bbl
21,000 bbl
525 tons
Variable Variable
1,759 acres 1,456 acres
52 TPD explosives Uncertain
used; amount of
residue unknown
See Retort Water
See Retort Hater
Major inorganic salts
Soluble inorganics high mobility.
Trace element mobility low.
See Dewatering Water; concentrations expected to Soluble inorganics of high mobility.
increase significantly Trace elements low to moderate mobility.
Similar to Sroundwater Quality; increased
biochemical oxygen demand
nitrates, See Cooling Water Blowdown.
Not applicable, except for spill potential
Sulfur species
Moderate to low mobility if spilled or
otherwise exploded.
Not applicable to local conditions, material returned
to manufacturer
Miscellaneous organics:9
Fuels
Oil and grease
Numerous hydrocarbons
Ammonium-nitrate
Soluble salts (uncertain) Soluble salts highly mobile. Trace el e-
Organics from process area (uncertain) ments, organics probably low mobility.
Soluble salts (uncertain) See Runoff
Aumonia
Nitrates
Fuel oil
uncertain) Inorganics probably of high mobility.
uncertain) Organics largely uncertain.
uncertain)
Maximum or total amounts used for full commercial operation,
^Constituents of importance are probably the same, although levels (concentrations) for raw shale are probably appreciably lower than for spent shale.
cFrom Table 6-2, Tract C-b water quality data, maximum concentrations (numbers rounded)
dFrom Table 3-2 (numbers rounded)
eFrom Table 3-6 (numbers rounded)
'From Slawson (1979); study of surface retorting and disposal operations proposed for Lease tracts U-a and U-b.
9Concentration uncertain, release dependent on spill events.
-------
• Preliminary ranking with regard to size of source:
Solid wastes Liquid wastes
1. .In-situ spent shale 1. Mine water, dewatering
2. Surface disposal of 2. Retort water
spent shale
— oily water treatment
3. Waste rock, raw shale
— foul water stripping
4. Sulfur
3. Cooling tower blowdown
5. Ammonium nitrate stockpile
4. Oil and fuel tank storage
6. Wastes from raw water
treatment 5. Runoff from facilities
7. Catalysts from sulfur 6. Sanitary waste water
recovery
7. Oil treatment and
8. Explosives residues upgrading
9. Disturbed areas
• Preliminary ranking with regard to potential pollutant concen-
tration, toxicity, etc.:
Solid wastes Liquid wastes
1. In-situ spent shale 1. Retort water
2. Surface disposal of spent -- oily water treatment
shale
— foul water stripping
3. Sulfur
2. Oil and fuel tank storage
4. Ammonium nitrate stockpile
3. Oil treatment and
5. Waste rock, raw shale upgrading
6. Explosives residues 4. Cooling tower blowdown
7. Wastes from raw water 5. Mine water, dewatering
treatment
6. Sanitary waste water
8. Catalysts from sulfur
recovery 7. Runoff from facilities
9. Disturbed areas
146
-------
Intermediate
These listings lead to the following composite first criterion ranking:
Relative ranking Potential pollution source
Highest In-situ spent shale disposal
Surface spent shale disposal
Retort water
Waste rock, raw shale
Sulfur
Mine water, dewatering
Cooling tower blowdown
Oil and fuel tank storage
Ammonium nitrate stockpile
Oil treatment and upgrading
Runoff from facilities
Sanitary waste water
Raw water treatment wastes
Catalysts from sulfur recovery
Explosives residues
Disturbed areas
To evaluate the potential mobility of groundwater pollutants, considera-
tion must be given to attenuation mechanisms. These, together with types of
pollutants affected, are as follows:
Lowest
Mechanism
Filtration
Adsorption
Biological degradation
Chemical reactions
Dispersion
Precipitation
Application
Suspended material, algae, and
large bacteria
Bacteria, viruses, and certain
trace elements, organics
Organic constituents
Certain inorganic constituents
Constituents not removed by
other mechanisms
Major inorganic, trace element,
and organic constituents
It should be noted that dispersion is a diluting mechanism. It does not
physically remove pollutants, and it is applicable to all pollutants which
are not attenuated by other mechanisms.
147
-------
to potential pollutant mobility is
Liquids
1. Mine water, dewatering
(assumed reinjected)
2. Retort water (some brought
to surface, some remains
in situ)
3. Cooling tower blowdown
4. Sanitary waste water
5. Oil and fuel storage
6. Runoff from facilities
7. Oil treatment and upgrading
A preliminary ranking with regard
presented below.
Solids
1. In-situ spent shale
2. Surface disposal of spent
shale
3. Ammonium nitrate stockpile
4. Explosives residues
5. Wastes from raw water
treatment
6. Catalysts from sulfur
recovery
7. Sulfur
8. Waste rock, raw shale
9. Disturbed areas
This ranking is based upon the predominant type of pollutants in the various
solid and liquid wastes. But equally important is how the waste reaches
groundwater. Those wastes released at the ground surface must travel farther
and there is more opportunity for attenuation than do wastes released under-
ground in direct contact with groundwater.
For the purposes of this preliminary ranking and because of the low rate
of groundwater use close to the oil shale tracts, the first criterion priority
ranking developed above will be used here to express the possible hazards to
potential water users (third criterion ranking). Priorities with regard to
this criterion can be expected to be quite site-specific and variable.
From the preceding discussions, a preliminary ranking of potential pol-
lution sources has been developed (Table 8-2). Uncertainties or information
voids exist in the data base used to develop this ranking. This is particu-
larly true in the areas of potential pollutant characterization and the mo-
bility of various major inorganic ions, trace elements, and organic species
to be encountered in oil shale development. In addition, site-specific de-
velopment plans and hydrogeology may result in modification of this ranking
for specific applications. Thus, professional judgment plays a significant
role in the development of Table 8-2.
This priority ranking serves as a general basis for the design of moni-
toring plans for modified in-situ oil shale developments, such as proposed
for Tracts C-a and C-b. Specific monitoring plan designs are addressed
148
-------
TABLE 8-2. PRELIMINARY PRIORITY RANKING OF POTENTIAL
POLLUTION SOURCES
Relative ranking
Potential pollution source
Highest
Intermediate
Lowest
In-situ spent shale disposal
Surface disposal of spent shale
Retort water
Mine water, dewatering
Sulfur
Cooling tower blowdown
Amnonium nitrate stockpiles
Explosives residues
Oil and fuel tank storage
Waste rock, raw shale
Sulfur
Oil treatment and upgrading
Sanitary waste water
Raw water treatment
Runoff from facilities
Catalysts from sulfur recovery
Disturbed areas
through evaluation of existing monitoring programs, identification of alter-
native monitoring approaches, and the selection of a monitoring program for
field implementation which addresses defined monitoring needs.
These considerations are presented in Sections 9, 10, and 11 of this re-
port using Tracts C-a and C-b as example cases. These discussions are used
to illustrate the monitoring design process which is a framework for decision-
making based on cost-effectiveness considerations. The framework presented
here is preliminary, largely due to the site-specific nature of the evalua-
tions, the absence of any testing or validation of recommendations at this
time, and only qualitative consideration of costs. In the second phase of
this project, preliminary results provided here will be tested and modified
as needed to develop monitoring design recommendations more generally appli-
cable to the modified in-situ'process.
149
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SECTION 9
EVALUATION OF EXISTING MONITORING
The results of baseline data collection programs on Lease Tracts C-a and
C-b are presented in Sections 5 and 6 of this report as example cases of
available data bases used for design of groundwater quality monitoring pro-
grams. This section presents an evaluation of operational monitoring programs
which were proposed by the tract developers.
The monitoring programs described are those employed or planned by tract
developers at the time of drafting this report. This description is provided
to define the general nature of these monitoring programs. The details of
developer monitoring programs may be modified from time to time by tract de-
velopers or regulatory agencies. Recent modifications may not be included in
the following description.
TRACT C-a MONITORING
Monitoring data collected during the Tract C-a MDP (Tables 9-1 and 9-2)
will be compared with baseline data using statistical methods, such as fre-
quency, scattergram, bivariant correlation, factor, discriminant function,
and trend analyses. These analyses are intended to identify anomalies and to
allow identification of the cause of the anomaly, such as changes in baseline
hydrology or environmental impact, largely by assessing water quality exceed-
ing expected fluctuations defined during the baseline studies.
Observation of such unexpected fluctuations will lead to efforts to de-
termine if tract development caused the observed changes. Subsequently, sam-
ple collection will be implemented to determine the type of contaminant and
to trace the source.
The hydrologic monitoring program includes sampling of surface waters at
spring and seep stations, at surface gaging stations, and at impoundments.
The rationale for the programs is summarized as follows:
• Springs and seeps program (Figure 9-1)
— Four of the springs and seeps were concluded to be hydrauli-
cally connected with the Upper Aquifer
•— Monitoring operation:
• If unexpected are flows observed, water quality will be
sampled
150
-------
TABLE 9-1. SUMMARY—PROPOSED HYDROLOGY MONITORING PROGRAM, TRACT C-a
Semi-
Continuously Quarterly Annually Other
SURFACE WATER:
Stream gaging stations3
(Figure 9-1)
DOC fractionation
(once initially)
Conductivity
Temperature
Flow
Limited water quality
Baseline water quality
Springs and seeps3
(Figure 9-1)
DOC fractionation
(once initially)
Flow
Conductivity
Temperature
PH
DOC
Surface water impoundments3
Baseline water quality'3
Limited water quality
GROUNDWATER:
Alluvial holes3
(Figure 9-1)
DOC fractionation (once
initially at new holes)
Water levels
Limited water quality"
Baseline water quality"
Dual aquifer monitor holes
(Figure 9-1)
Water levels
Baseline water quality"
x(6)
x(6)
x(6)
x(3)
x(6)
x(6)
x(6)
x(6)
x(6)
x(6)
x(6)
x(5)
x(8)
x(G)
x(8)
x(6){
1 'indicates the number of sampling sites.
aWhen water is present.
These analyses will be performed downgradient of any surface water
impoundments which are constructed.
Additional measurements will be made if unexpected events occur.
See Table 9-2 for listing of water quality constituents.
p.
To be conducted annually.
Note: Samples will be retained 30 days following submission of year-end report.
151
-------
TABLE 9-2. WATER QUALITY SAMPLING, TRACT C-a
tn
ro
Constituents
General water quality
measures
Specific conductance
Dissolved solids
Alkalinity
pH
Temperature
Fecal coliforms
Total coliforms
Color
Odor
Turbidity
Dissolved oxygen
Major inorganics
Sulfate
Sulfide
Bicarbonate
Carbonate
Chloride
Fluoride
Alluvial wells
Q S
X X
X
X X
X X
X X
X
X
X X
X
X X
X
X X
X X
Deep wells
A
X
X
X
X
X
X
X
X
X
X
X
X
X
Seeps and Stream gaging
springs stations
Q Q S
X X
X
X XX
X X
X X
X
X
X
X
X
X
X X
X
X X
X
X X
X X
Surface
impoundments
Q S
X
X
X X
X X
X
X
X
X
X
X
X
X X
X
X X
X
X X
X X
(continued)
-------
TABLE 9-2. (continued)
en
CO
Alluvial wells
Constituents Q
Major inorganics (continued)
Calcium X
Magnesium X
Potassium X
Silica X
Sodium X
Ammonia
Nitrate+ni trite X
Dissolved phosphate
Total phosphate
Orthophosphate
Organic constituents
DOC
DOC fractionation
BOD
COD
Suspended organic
carbon
Phenol s
Oil and grease
S
X
X
X
X
X
X
X
X
X
X
X
X
Deep wells
A
X
X
X
X
X
X
X
X
X
X
X
Seeps and Stream gaging
springs stations
Q Q
X
X
X
X
X
X
X X
S
X
X
X
X
X
X
X
X
X
X
X
x«
X
X
X
X
X
Surface
impoundments
Q S
X X
X X
X X
X X
X X
X
X
X
X
X
X X
xd
X
X
X
X
X
(continued)
-------
TABLE 9-2 (continued)
Alluvial
Constituents Q
Organic constituents (continued)
Kjeldahl nitrogen
ITCAS
Cyan i de
Pesticides
Trace elements
Alumi num
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromi de
C admi urn
Chromi urn
Copper
Germanium
Gallium
Iron
Lead
wells
S
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep wellsb
A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Seeps and Stream gaging Surface
springs stations impoundments
Q Q S Q
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
(continued)
S
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
TABLE 9-2 (continued)
en
Alluvial wells
Constituents Q
Trace elements (continued)
Lithium
Mercury
Molybdenum
Manganese
Nickel
Selenium
Strontium
Titanium
Vanadium
Zirconium
Zinc
Radiological constituents
Gross alpha6
Gross betaf
S
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep wells
A
X
X
X
X
X
X
X
X
X
X
X
X
X
Seeps and Stream gaging
springs stations
Q Q S
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface
impoundments
Q S
X
X
X
X
X
X
X
X
X
X
X
X
X
Sampling frequency: Q = quarterly; S = semi annually; A = annually.
Upper Aquifer.
°Sampled when water present.
Once initially and repeated thereafter if DOC exceeds four times baseline mean.
elf gross alpha > 4 pCi/1, then Ra-226 and natural uranium added.
If gross beta > 100 pCi/1, then Sr-90 and Ce-137 added.
-------
A SPRINGS AND SEEPS
0 ALLUVIAL WELLS
A STREAM GAGES
R100W
R99W
R98W
R97W
Figure 9-1. Locations of MDP surface water and groundwater
monitoring stations, Tract C-a.
156
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• Identification of water quality perturbations will be
based on conductivity and DOC monitoring
- No change will be assumed to have occurred if conductiv-
is less than 20 percent above baseline maximum or more
than 20 percent below baseline minimum
- DOC fractionation will follow observation of DOC greater
than four times baseline mean concentration
• Surface gaging station program (Figure 9-1)
— If unexpected flows are observed, additional samples will be
collected (flow, conductivity, temperature, and pH) as needed
to identify source
-- DOC fractionation will follow observation of DOC greater than
four times baseline mean concentration
— If conductivity at Station D (Figure 9-1), located at the
confluence of watersheds draining the tract, exceeds the 1
percent frequency level (as defined for the baseline) for
more than 3 consecutive days, samples will be analyzed for
sodium, chloride, silica, calcium, magnesium, sulfate, po-
tassium, bicarbonate, nitrate plus nitrite, pH, and DOC to
assess origin of anomaly; the semiannual list of constituents
may also be sampled
-- An automatic (predetermined periodicity) sampler will be in-
stalled at Station D; samples will be analyzed for oil and
grease to detect accidental spills and leaks
— Discriminant function analysis (using alkalinity, sodium,
silica, fluoride, and pH) is used to classify source of
waters (alluvium, Upper Aquifer, or Lower Aquifer); corre-
lation studies will also be utilized
— Data will also be compared to baseline data plotted on tri-
linear diagrams
-- Cation-anion balances will be used to check data.
Groundwater monitoring programs include sampling of alluvium, Upper
Aquifer, and Lower Aquifer. Features of thse programs for the MDP are sum-
marized as follows:
• Alluvial aquifers (Figure 9-1)
— Increased concentrations of DOC or oil and grease will lead
to additional analyses to determine type of material (e.g.,
No. 2 diesel fuel, gasoline, shale oil, etc.)
157
-------
— DOC fractionation will follow observation of DOC levels four
times baseline mean concentration
— Discriminant function analysis, correlation studies, and tri-
ll near diagrams will be used as described above
• Deep aquifers (Figure 9-1): Water quality data will be compared
to baseline study trilinear diagrams and correlation studies.
In addition to the above-described monitoring during the MDP, a program
specifically oriented toward monitoring the MDP pump tests (Table 9-3) is de-
scribed as follows:
• Three additional surface water stations
• Eight additional alluvial sites (11 total holes)
• Sixteen erosion and sedimentation sites.
For water quality monitoring, if pH varies 1.5 units from baseline values or
conductivity varies ±20 percent for 3 consecutive days, then major plus mi-
nor constituents will be analyzed.
TRACT C-b MONITORING
Proposed monitoring of Tract C-b development also includes sampling of
surface streams, springs and seeps, alluvial wells, and deep aquifer wells
(Table 9-4). Features of the monitoring program are summarized as follows:
• Springs and seeps (Figure 9-2)
-- If monthly sampled levels of pH, conductivity, dissolved oxy-
gen, and temperature exceed baseline maximum or minimum lev-
els by ±20 percent, additional water quality samples will
be collected (the sampling frequency was changed to weekly in
April 1979)
-- Semiannual DOC fractionation-will be at two springs selected
by the AOSS Office
-- Flow will be monitored on the following schedule:
Frequency* Station
Quarterly S-3, S-7
Semi annually S-l, S-6
Annually S-2, S-4, S-9, S-10
*(A11 stations are monitored weekly as of April 1979.)
158
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TABLE 9-3. SUMMARY OF MDP AQUIFER TEST MONITORING PROGRAM, TRACT C-a
Program component
Monitoring sites
Summary of sampling
New surface water
monitoring sites
(Figure 9-1)
New alluvial wells
(Figure 9-1)
Deep aquifer wells
(Figure 9-1)
Erosion and
sedimentation
monitoring sites
1. Corral Gulch at 84 Ranch
2. Sec. 1, T1S, R98W
3. Sec. I, TIN, R98W
1. G-S S-27 Triple
2. G-S S-ll Triple
3. G-S S-11A Dual
4. G-S S-24 Single
5. G-S S-28 Dual
6. G-S S-28A Dual
7. G-S S-29 Dual
8. G-S S-29A Dual
1. Upper:
2. Lower:
G-S 11
G-S 15
G-S Ml
G-S M2
G-S M3
G-S M4
G-S 15
Sixteen sites distributed
along Corral Gulch and
Yellow Creek, on and below
Tract C-a
Flow measured with flume
or weir with continuous
recorder.
Measure pH and conduc-
tivity:
• Daily for 3 days
prior to pump test
discharge
• Twice daily for
initial week of
discharge
• Twice per month
thereafter.
Measure water level,
conductivity, tempera-
ture, and pH daily for
3 days prior to pump
test discharge.
Measure major or minor
chemical constituents in
wells with water or as
water is encountered:
• Once daily for
initial 2-3 days
of discharge
• Once weekly
thereafter
Measure water level once
daily for 2-3 days after
pumping started to estab-
lished trend, then weekly
Measure channel cross
sections. Photograph
si tes.
159
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TABLE 9-4. WATER QUALITY SAMPLING PROGRAM—TRACT C-b
en
O
General water quality
measures
Specific conductance
Dissolved solids
Alkalinity
PH
Temperature
Fecal coliforms
Total coliforms
Dissolved oxygen
Hardness
Major organics
Sulfate
Sulfide
Bicarbonate
Carbonate
Chloride
Fluoride
Calcium
Magnesium
Potassium
Silica
Sodium
Ammonia
Alluvial wellsb
M Q
X
X
X
X X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep aquifers
S A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Seeps and springs
M Q or S S A
X
X
X
X X
X X
X
X
X
X X
X
X
X
X
X
X
X
X
X
Stream gaging stations
M or Q Q S A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
(continued)
-------
TABLE 9-4 (continued)
CT>
Organic constituents
Nitrate
Nitrate + nitrite
Total phosphate
DOC
DOC fractionation
BOD
COD
Suspended organic carbon
Phenols
Oil and grease
Kjeldahl nitrogen
MB AS
Cyan i de
PNA
Trace elements
Aluminum
Arsenic
Barium
Boron
Bromi de
Cadmium
Chromi urn
Cobalt
Alluvial wellsb
M Q
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep aquifers
S A
X
X
X
X'
X
X
X
X
X
X
X
X
X
X
X
Seeps and springs
M Q or S S A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Stream gaging stations
M or Q Q S A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
(continued)
-------
TABLE 9-4 (continued)
en
ro
Trace elements (continued)
Copper
Iron
Lead
Lithium
Mercury
Molybdenum
Manganese
Nickel
Selenium
Silver
Strontium
Zinc
Complete element scan
Radiological constituents
Gross alpha
Gross beta
Sediments
Suspended sediment
Sediment pesticide
Sediment characterization
Alluvial wells0
M Q
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Deep aquifers
S A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Seeps and springs
M Q or S S A
X
X
X
X
X
X
X
X
X
X
X
X
Stream gaging stations.
M or Q Q S A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sampling frequency: M = monthly; Q = quarterly; S = semiannually; A = annually.
Water quality sampling of alluvial wells has been changed to a quarterly frequency.
-------
1,061
A STREAM GAGES
A SPRINGS AND SEEPS
Figure 9-2. Surface water monitoring stations, Tract C-b.
• Surface gaging stations (Figure 9-2)
-- Monthly and quarterly sampling programs are conducted at four
major stations: 007, 022, 058,' 061
-- Additional quarterly sampling will be conducted at ephemeral
stream stations on an opportunistic basis (when flow is
present)
• Alluvial wells (Figure 9-3): In addition to the program shown
in Table 9-4 and Figure 9-3, wells A-2, A-3, A-5, A-6, and A-7
will be monitored on a "reduced basis" when A-2A, A-3A, A-5A,
A-6A, and A-7A are completed
• Upper Aquifer wells (Figure 9-3): Polynuclear aromatics (PNA)
will be sampled annually at "selected" locations and species
analyzed will be determined "at a later date."
The Tract C-b monitoring plan designates the following chemical constit-
uents as "indicator variables:"
163
-------
• ALLUVIAL WELLS
Q DEEP AQUIFER WELLS
Figure 9-3. Alluvial and deep aquifer monitoring wells,
Tract C-b.
Indicator variable Springs Gaging stations Alluvium Upper Aquifer
General water quality
measures:
Conductivity
Coliform bacteria
pH
Temperature
TDS
Inorganic chemical
constituents:
Ammonia
Arsenic
Boron
Fluoride
Mercury
Selenium
Organic chemical
constituents:
DOC
MBAS
Oil and grease
Phenolics
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
164
-------
Tract C-b monitoring plan "indicator variables" (continued)
Indicator variable Springs Gaging stations Alluvium Upper Aquifer
Radiological water quality
(Table 9-4) X
Groundwater level X X
Sediment X
Streamflow X
Precipitation X
OTHER MONITORING PROGRAMS
Monitoring and testing programs conducted by organizations other than the
tract developers may also be useful for monitoring the impact of tract devel-
opment on groundwater quality. One example is the program of surface water
and groundwater sampling conducted by the U.S. Geological Survey in the Pi-
ce an ce Basin (Welder and Saulnier, 1974; Weeks and Welder, 1974; Ficke, Weeks,
and Welder, 1974). Many of these programs are regional in focus but, although
they offer data useful for characterizing the hydrgeology and water quality
of development tract areas, they probably do not provide sampling sites suit-
able for site- and source-specific monitoring programs.
GENERAL MONITORING APPROACH
Baseline studies conducted on Tracts C-a and C-b can be generally described
as regionally focused programs. Proposed monitoring programs (considering
deep aquifers which are the emphasis of this study) are also largely regional
in orientation. Consider, for example, Tract C-a development. Figure 9-4
shows monitoring plans for the MDP operation. Five deep (dual completion)
wells are located approximately 2 miles or more from the MDP area, two gener-
ally to the south (G-S 11 and G-S 15) and three generally to the north (G-S
Ml, G-S M4, and G-S M2). Figure 9-4 shows an anisotropic flow net for the
Upper Aquifer superimposed on the plot plan for Tract C-a. Comparison of
these flow net data with the deep well locations identified on Figure 9-1
indicates that no upgradient-downgradient (relative to the MDP area) pairs of
wells are included in the MDP monitoring plan. G-S 11 and G-S Ml may provide
general background water quality data, but none of the other wells are shown
to be directly downgradient. Figure 9-4 indicates that CE 709 and G-S 9 may
provide existing well upgradient monitoring sites for the MDP and G-S 4-5, TO
3, and CE 702 may be better existing downgradient sites for monitoring MDP
operations. Even so, these downgradient wells are located about h mile (G-S
4-5) to 1 mile (TO 3 and CE 702) from the MDP area. A better option may be a
new well or wells located at the downgradient edge of the MDP retort field.
Another alternative which needs further assessment is the utility of wells
included in the dewatering-reinjection program for monitoring after cessation
of dewatering.
A similar situation exists for Tract C-b monitoring as illustrated in Fig-
ure 9-5. Several wells (32X-12, 33X-1, and Cb-1) are located in the inmediate
165
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PROCESSED SHALE
DISPOSAL PILE
CRUSHED
DEVELOPMENT
ORE DISPOSAL
DISTANCE (miles)
Figure 9-4. Anisotropic flow net of Upper Aquifer superimposed on
Tract C-a plot plan and existing deep aquifer wells.
166
-------
SG20*
•SG19
DIRECTION OF MAXIMUM
PERMEABILITY
KEY: 1 INITIAL IN SITU RETORT FIELD
2 MINE SUPPORT AND ACCESS
3 MINED ROCK AND RAW SHALE DISPOSAL.
COTTONWOOD GULCH
4 COTTONWOOD IMPOUNDMENT DAM
5 OIL STORAGE
6 WASTEWAT6R POND
7 STACKS
8 OIL TREATMENT
9 GAS TREATMENT
10 SORGHUM GULCH
II IMPOUNDMENT DAM
ASG-8
SG18A
K6Y TO WELLS
UPPEfl AQUIFER
LOWER AQUIFER
DUAL COMPLETIONS
Figure 9-5. Anisotropic flow net of Upper Aquifer superimposed on
Tract C-b development plot plan.
vicinity of (or within) the proposed retort field. Wells 32X-12 and 33X-1
are Upper Aquifer wells; they are open holes with packers set at the top of
the Mahogany Zone. They will be impacted by mining. Well Cb-1 is perforated
in the Lower Aquifer zone. No wells are located downgradient of the retort
field area. Until recently, the Uinta Aquifer (Ui) was not monitored in or
near the retort field. The new wells were completed in the Uinta downgradient
of the retort field.
Monitoring of dewatering-reinjection wells may be better focused on the
wells themselves except for hydrogeologic modifications (e.g., head levels).
SAMPLING METHODS
In order to better evaluate existing or proposed monitoring programs, as
well as the existing data base, sampling methods being utilized on Tracts C-a
and C-b were reviewed in available documents and by direct observation.
167
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Tract C-a Sampling
Groundwater quality samples on Tract C-a are collected by bailing. Sim-
ilar procedures are used for both alluvial and deep aquifer sampling. Suffi-
cient water is bailed to fill the required sample bottles. Samples requiring
filtration are filtered in the field using a nitrogen-positive pressure filter
apparatus. Field measurements of pH (using colorimetric paper), conductivity
{using conductivity bridge), and temperature are made immediately after sample
collection.
Comments from observation of field sample collection (in December 1978)
and response by tract developers are summarized as follows:
• Comments
1. Alluvial wells are constructed with approximately a 6-inch
outer steel casing and <3-inch PVC inner casing for sam-
pling. When bailed, these wells produce very muddy water
which probably reflects fine sediment in the bottom of the
well and not the local groundwater. More representative sam-
ples would be obtained from a gravel-packed, fully developed
well and from a well pumped for sampling.
2. To obtain a sample more representative of groundwaters rather
than waters which may have been sitting in the well casing
for some time, it would be necessary to bail several well
volumes before collecting samples for analysis. At present,
only enough water is bailed to fill sample bottles.
3. How well to field pH measurements made with colorimetric tape
compare with laboratory pH data? As turbidity is a severe
problem in some of the wells, it would be better to filter
the samples and then test for pH (and also electrical conduc-
tivity). In addition, a watertight case with desiccant mate-
rial for storage of indicator tape may be useful for assuring
the consistency of pH tape data.
4. Field personnel indicated that 3 to 4 days delay is common
prior to delivery of samples to the analytical laboratory.
Has any work been done to look at the effects of this delay
time on analytical results?
5. Construction of the deep wells is similar to shallow wells,
except that perforated zones are about 300 feet thick and
piezometric levels stand 100 to 200 feet above the perfora-
tions. Sampling of these wells was not observed in December
1978; however, it was reported that these wells are not pumped
before sampling and that these wells commonly contain dirty
or muddy water. As noted above, this probably is not repre-
sentative of local groundwater. A 6-inch casing, 300 feet
long, contains about 450 gallons of water. Approximately 4
gallons are bailed in a single sampling. Thus, the relation
168
-------
between the water sampled (which may have been in the well
for some time) and the local groundwater may be questionable.
6. Steel casing may affect trace metal and organic chemical
analyses, as these constituents may be absorbed by metal
oxides on the casing.
7. A monthly sampling frequency for many of the alluvial wells
seems excessive, particularly those which contain little or
no water. These monitoring efforts are related to detection
of leakage from the reinjection program. However, with the
present operation of the reinjection system and the continu-
ing dry state of many of the wells, some adjustment may be
justified for the future.
• Response from Rio Blanco Oil Shale Company
1. The statement made is generally correct with the following
exception: the alluvial monitor holes are gravel-packed and
have been developed. The nature of the alluvial aquifers is
such that coarser material has been deposited with very fine
clay-like material as water is withdrawn from the wells.
This fine, clay-like material is also produced from the well.
It is our opinion that the majority of the sediment produced
in the sample is from the aquifer. If sediment-free wells
were to be constructed, the cost would be quite high in that
a very fine, wire-wound screen would have to be used with a
carefully selected gravel pack. Even if these precautions
were taken, it is still not 100 percent certain that sediment-
free water could be produced.
2. In some of the alluvial holes, it is possible to remove a few
volumes of water before collecting the sample for analysis.
However, in most of the holes, the transmissivity of the
aquifer is such that after removing a few well volumes, the
well would be dry and would require several days recovery be-
fore enough water would be in the well to obtain a sample.
3. A comparison of field pH data collected with a colorimetric
tape cannot readily be compared with laboratory pH data since
pH is not stable.
4. The field, as we all know, is quite remote from any analyti-
cal laboratory. We have been quite conscious of the delay
resulting from getting' the samples collected and to the lab-
oratory for analysis. This delay, however, is kept to a min-
imum. At the present time, we have not conducted any work to
compare the effects of this delay on the analysis.
5. The statement is correct in that we do not pump the wells be-
fore sampling. We do, however, collect the sample in the
aquifer zone where water should be moving through the well.
169
-------
We have made comparisons of the samples produced from the
monitoring program with those produced from pumping tests.
The results of these comparisons are quite favorable in that
we find the analysis resulting from the two methods of col-
lecting water very similar.
6. The use of steel casing is quite common in the completion of
the observation holes. At the time the holes were completed,
there was no other material economically available other than
steel.
7. We agree.
Tract C-b Sampling
Two methods of sample collection are used for groundwater quality moni-
toring on Tract C-b. Pumping is used to sample alluvial wells and swabbing
is used to sample deep aquifers. In sampling deep aquifers, several swabbing-
discharge runs are made before samples for laboratory analysis are collected.
Field measurements of pH and conductivity using field instruments are made at
the time of sampling.
Comments and recommendations from observation of field collection opera-
tions (in November 1978) are summarized as follows:
• Bedrock aquifer sampling
— Comments
1. The diameter of the piezometers in use (2-3/8 inches) is
too small for installation of a submersible pump for sam-
pling. Use of pumping to obtain samples allows sampling a
larger volume of the aquifer and provides more representa-
tive samples for analysis.
2. The swabbing method being used may accelerate plugging of
piezometer perforations. The small diameter of the pie-
zometers also increases the likelihood of the plugging.
Plugging may have resulted in retrieval of only a small
volume of water from the well observed in November 1978;
the third or fourth swabbing pass yielded little or no wa-
ter. Pumping for sampling would help keep wells developed.
3. Grease and oil were observed on the cable and other swab-
bing equipment. Since swabbing equipment is also used for
oil well work, the potential exists for contamination of
samples by sampling equipment.
4. Steel piezometers may affect trace metal and organic
chemical analyses. These constituents may be adsorbed on
metal oxides on the casing.
170
-------
— Recommendations
1. The volume of water swabbed should be measured as should
the number of swabbing passes in each piezometer. Such
data would be useful for subsequent sampling surveys and
also for evaluating plugging of wells.
2. The conductivity meter used in the field should either have
a temperature compensator or water temperature should be
measured along with conductivity at the time of sampling.
Without this procedure, field data from one survey to the
next cannot be compared; also, lab and field data cannot
be compared.
3. Manufacturers' instructions and maintenance information
for field instruments should be carried with field instru-
ments, along with other sampling procedure instructions
for the field team.
4. Since conductivity is being used to determine when it is
appropriate to collect samples for chemical analysis, data
from previous surveys should be available in the field for
reference.
5. Sample filtration and preservation (including addition of
chemical preservatives and icing of samples) should take
place as soon as possible after collection, preferably in
the field immediately after sample collection.
6. The depth of each swabbing run should be recorded.
7. For the recompletion program, PVC should be used in place
of steel casing wherever possible.
8. Wherever possible (i.e., where adequately sized (>4-inch)
casing is available), samples should be obtained by
pumping.
9. Cable and swabbing cups previously used in oil field oper-
ations should be cleaned thoroughly before use in water
quality sampling. Ideally, they should also be clean'ed
after each sampling to avoid contamination from one moni-
tor well to another. However, a sufficient number of
swabbing passes in each piezometer may minimize this lat-
ter source of contamination.
• Alluvial aquifer sampling
-- Comments
Sampling of alluvial wells was not observed during the
November tour. Alluvial wells are equipped with a
171
-------
4-inch-diameter PVC casing and are sampled by pumping.
— Recommendations
1. Initial testing of each well with frequent sampling of
discharge conductivity can be used to identify appropriate
pumping time before sampling.
2. Eight-inch or larger wells would be required for any pump
testing of the alluvial aquifer.
3. If pumping is used, it is not necessary to complete pie-
zometers at various depths in the alluvium. Pumping would
sample the aquifer profile in composite.
It should be noted that many of these recommendations were implemented
by Tract C-b developers during 1979.
OTHER SAMPLING CONSIDERATIONS
Selection of Sampling Method
Previous discussion in this report has indicated that well completion
and sampling methods can play an important part in determining the utility of
monitoring data. During baseline studies on the oil shale tracts, several
methods have been used to collect water quality samples: bailing, swabbing,
and pumping. Each of these methods may sample a different part of the
aquifer-well system and can result in different data for the same point in
time and space.
Alluvial wells on Tract C-b have been sampled by both bailing and by
pumping (C-b Shale Oil Venture, 1977b). Relatively high fluoride levels (5
mg/1) were reported for the initial sampling run when samples were collected
by bailing. Subsequent samples for the 2-year baseline studies were col-
lected by pumping and observed fluoride levels were lower and relatively con-
stant (mean = 0.65 mg/1 with standard error of mean = 0.09). The differences
seem to be related to sampling method.
On Tract C-a, all groundwater quality samples are collected by bailing.
Sufficient water is bailed to fill the required sample bottles. One of the
goals of sampling is to obtain water quality data which are representative of
water within the aquifer zone being sampled. Aside from problems of well
completion, bailing of a small volume from a well bore may not provide the
desired representative sample. As noted above, construction of deep wells
may include a perforated zone of perhaps 300 feet. A 6-inch casing, 300 feet
long, contains about 450 gallons of water. If approximately 4 gallons are
bailed for sampling on, for example, a quarterly basis, water sampled may not
be representative of local groundwater, but rather of the water which has
been standing in the well bore (perhaps a very different physiochemical envi-
ronment) for some time.
172
-------
The implication here is that care must be taken with the use of bailing
as a sampling technique. For example, tests conducted by Rio Blanco Oil Shale
Project (Tract C-a) indicated that samples bailed from well intervals perfor-
ated in aquifer zones produced results very comparable to pumped water sam-
ples. However, samples bailed from the well interval above the perforated
zone (and where water is stagnant within the well) yielded water quality data
quite different from either pumped samples or samples bailed from the aquifer
zone.
When swabbing is used to collect samples, there are several factors
which influence the amount of water produced and also possibly the level of
water quality constituents observed:
• Length of perforated interval swabbed
• Type of perforation
• Space between well and aquifer material; and between swabbing
cup and well casing
• Depth to water
• Height of water column swabbed
• Speed of swabbing.
During swabbing runs on Tract C-b, conductivity measurements of each swabbing
run are made as one criterion for determining when to collect samples for
analysis. Wide ranges of conductivity may be observed during a given sam-
pling effort (Table 9-5). Conductivity of initial swab runs may be higher or
lower than the final value. The selection of when samples are collected
(i.e., after what number of swab runs) can be seen to significantly affect
the results of water quality sampling.
Pumping to collect water quality samples may produce representative
aquifer samples, but pumping time and well completion play an important role
in determining the results of sampling. For example, dissolved solids-levels
in pump test discharges (at well AT-1 on Tract C-b) were lower than levels
observed in samples collected by swabbing. One explanation is that relatively
good water quality zones are also zones of relatively high hydraulic conduc-
tivity. Pumping of wells completed in both such good water quality zones and
poorer water zones would draw relatively more water from the good water qual-
ity zone, producing relatively low dissolved solids levels (C-b Shale Oil
Venture, 1977b). If continued pumping can exhaust water in the good water
quality Kine, water quality can decline with continued pumping (Table 9-6).
Well Completion
As previously discussed (see Sections 5 and 6), well completion has a
significant influence on hydrogeologic and water quality data. For example,
consider the following data related to well recompletions on Tract C-b:
173
-------
TABLE 9-5. CONDUCTIVITY LEVEL OF SWABBED SAMPLES, TRACT C-b,
FALL 1976 (C-b Shale Oil Venture, 1977b).
Well/string
number
SG-1-1
S6-1-2
SG-9-1
S6-9-2
S6-21
Cb-4
SG-11-12
SG-11-2
SG-11-3
SG-18A
Cb-2
SG-6-1
SG-6-2
SG-6-3
Gallons
swabbed
1,260
2,840
2,100
1,150
3,210
2,300
1,220
530
300
—
2,920
550
630
160
Observed
conductivity
range
(ymhos/cm)
3,000
1,200
1,300
1,850
750
800
14,000
800
1,600
750
1,600
1,800
1,300
1,350
- 10,000
- 1,500
- 3,400
- 2,100
- 1,150
- 900
- 32,000
- 4,000
- 1,800
- 1,250
- 1,650
- 3,100
- 1,400
- 1,550
Final
conductivity
(ymhos/cm)
8,250
1,250
2,000
1,850
1,000
825
22,000
1,200
1,790
1,000
1,600
3,000
1,300
1,550
TABLE 9-6. FLUORIDE AND BORON FROM LOWER AQUIFER
TEST (C-b Shale Oil Venture, 1977b)
Date (1975)
January 20
February 5
February 23
February 24
February 25
February 27
February 28
March 1
March 3
March 5
March 7
March 19
Fluoride
(mg/1)
18.0
18.1
20.0
20.1
20.4
18.4
20.4
20.2
19.0
20.0
21.2
23.2
Boron
(mg/1)
0.65
0.88
1.15
1.10
1.13
1.2
1.6
1.42
2.58
2.02
2.18
2.00
174
-------
IDS (mg/1) IDS (rag/1)
in water before in water after New well
Original well recompletion recompletion designation
SG-11-1 39,000 16,000 SG-11-1R
SG-10 42,000 2,800 SG-10R
SG-17-1 28,000 4,300 SG-17-1R
These wells had initially encountered, and had been open to, an interval con-
taining highly saline water which appeared to have a higher hydrostatic head
than the overlying aquifer intervals. Thus, water collected from these over-
lying layers was affected by the interconnection. Recompletions were under-
taken to isolate these different water quality bodies.
Thus, with initial data collection and the resultant gain in knowledge
about the hydrogeologic system, modifications in well construction may be
needed. An extensive recompletion program is proposed for Tract C-b to address
the present concept of a stratified aquifer system.
Analysis of the hydrologic testing which has been completed on Tract C-b
to date indicates that the simplified concept of an "Upper Aquifer" is, in
reality, a more complex system comprised of highly stratified layers of dif-
ferent permeability. In the initial mine plans, waters of the Upper Aquifer
are projected to remain segregated from other waters of the Lower Aquifer.
During the first phase of shaft sink'ing, very little, if any, stress will be
put on the Upper Aquifer. However, major stress will be applied on the Upper
Aquifer by lateral drifting and subsequent dewatering as the mine expands.
As this phase of development progresses, the Upper Aquifer will be monitored
with present drill holes on and off Tract C-b. According to initial plans of
developers, additional completion of existing holes, and perhaps additional
holes, were to be made to isolate the "Uinta Aquifer" from the other Upper
Aquifer subunits (Figure 9-6). However, data provided in Figures 9-7 and 9-8,
and Tables 9-7 and 9-8, do not clearly indicate this fact. The Uinta Aquifer
is highly protective and permeable only in the northwest part of Tract C-b
(in the vicinity of the in-situ retort field). It is predicted, with the
present scheme for dewatering, that effects above the Four Senators Zone will
be minimal since the Four Senators Zone acts as an aquitard or possibly an
aquiclude, prohibiting vertical movement of water within the Upper Aquifer
zone. Fracturing of the Four Senators Zone during mine and retort development
may alter this situation. Later analysis by developers led to the inclusion
of the Uinta Aquifer in
The proposed Tract C-b monitoring program uses the present wells on and
off tract. In general, modifications will be made in the shallow tubing
strings so that the sections above and below the Four Senators Zone can be
monitored separately. New wells 33X-1 and 32X-12 are included in the moni-
toring program (Figure 9-6), although they are expected to.be impacted by
mining and hence may be of limited use. Figure 9-4 shows the present comple-
tions of deep wells on tract. Figure 9-7 contains the planned recompletions
175
-------
0 i—
500
£
X
D.
UJ
0
1000
1500
2000
AQUIFER UNIT DETERMINED
BY SPINNER-PUMP TEST
AQUITARD
UINTA AQUIFER
UPC-i
BASE OF UINTA FORMATION
FOUR SENATORS ZONE
UPC2
— BASE A-GROOVE
-30' BELOW BASE A-GROOVE-
LPC3
— TOP R-5 20NE-
— MIDDLE R-5 ZONE-
— BASE L-4 ZONE-
T
LPC4
J_
Figure 9-6. Generalized aquif er-aqui tard system on Tract C-b.
176
-------
CN CO
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Figure 9-7. Current well completions, subsurface hydrology monitoring program, Tract C-b.
-------
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\ LIMITS OF SECTION OPEN
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100 0 400 800
FEET
VERTICAL SCALE
HORIZONTAL SCALE NONE
Figure 9-8. Planned well completions, subsurface hydrology monitoring program, Tract C-b,
-------
TABLE 9-7. UPPER AQUIFER MONITORING NETWORK (BEFORE RECOMPLETIONS)
Cb-2
Cb-4
AT-1C #3
SG-1 #2
S6-6 13
SG-8 #2
S6-9 12
SG-10A
SG-11 #3
S6-17 #2
SG-18A
SG-19
SG-20
SG-21
AFTER RECOMPLETIONS: Uj, UPC^ UPC2
CLOSE IN DURING ANCILLARY DEVELOPMENT REMOTE DURING ANCILLARY DEVELOPMENT
Cb-2
SG-1 #2
SG-1A
SG-6 #3
SG-lOa #1
SG-20 #1
AT-1B #3
33X-1 #3
32X-12 #3
UPCi)
(UPCi)
(UPC2)
(UPCi),
(UPC2),
(UPC2),
(UPCi)
(UPC2),
(UPC2),
Cb-3
Cb-4
SG-9 #2
11
#2
#3
#4
#4
(UPC2)
(UPCi)
(UPC!)
(UPC!)a
(UPCi)a
56-11 #2
SG-17 12
SG-18A 12
SG-19
SG-21
#3
(UPC2)
(UPC2)
(UPC2)
(UPC2),
(UPC2),
(UPC2),
(UPC!)
(UPC2),
#3
#3
#3
#4
(upcj)
(UPCi)
(UPC!)
aThese recompletions have been deleted by developers.
TABLE 9-8. LOWER AQUIFER MONITORING NETWORK (BEFORE RECOMPLETIONS)
Cb-1
AT-1C #1
AT-1C #2
SG-1 #1
SG-6 #1
S6-6 #2
SG-8R
SG-9 #1
SG-10
SG-10R
SG-11 HR
SG-11 #2
S6-17 I1R
AFTER RECOMPLETIONS: LPC3, LPC4
CLOSE IN DURING ANCILLARY DEVELOPMENT REMOTE DURING ANCILLARY DEVELOPMENT
SG-1 #1
SG-6 #2
SG-10
SG-20 #1
AT-1A
33X-1 #1
32X-12 #1
(LPC3)
(LPC3)
(LPC3
LPC3)
(LPC3)
(LPCJ), #2
(LPC4), #2
(LPC3)a
(LPC3)a
SG-9 #1
SG-11 #1
SG-17 #1
SG-18A #1
SG-21 11
SG-8
(LPC3)
(LPC3)
(LPC3)
(LPC3)
(LPCJ), #2
(LPC3)
aThese recompletions have been deleted by tract developers.
179
-------
of existing deep wells to correspond to the stratified aquifer configuration
and present dewatering plans.
The Lower Aquifer is also a complex system of highly stratified units of
different permeability. During the ancillary development stage when the major
stress is applied to the aquifers and with subsequent dewatering, existing
deep holes on and off tract will be monitored for quality and quantity effects
produced by the withdrawal of mine water. A segregation of all lower level
mine water and subsequent treatment before discharge are probably required
since the quality of this water is poorer than that of the Upper Aquifer wa-
ter. Figure 9-6 shows the Lower Aquifer subdivided into the LPC/3 and LPC4
zones. These intervals (especially the LPC3 subzone) may have to be de-
watered for the creation of underground retorts. To monitor the effect of
this dewatering, the recompletions of Table 9-8 and Figure 9-6 are necessary.
The Mahogany Zone is judged by the C-b Shale Oil Venture to be an impermeable
barrier so that potential subsequent dewatering in the LPC^ and LPC4 zones
would have minimal effects on the upper zones over the short term. As dis-
cussed elsewhere in this report, these conclusions on site-specific hydro-
geology are open to question.
As in the case of the Upper Aquifer, the deep tubing strings will also
be recompleted to correspond to the multiaquifer concept. The wells as pres-
ently completed observe the entire "Lower Aquifer" from the Mahogany Zone to
the terminal depth of all holes. With the planned completions, these separ-
ate units will be isolated and monitored separately.
Deep aquifer wells on Tract C-a are largely dual completions with per-
forated intervals above and below the Mahogany Zone (Figure 9-9). No more
detailed identification and monitoring of aquifer units is included in Tract
C-a development plans.
MONITORING EVALUATION
Monitoring deficiencies may be sepented into two general categories:
1. Deficiencies in information (e.g., characteristics of poten-
tial pollution sources, potential pollutants, hydrogeology,
etc.) needed for the development of a cost-effective monitor-
ing program
2. Deficiencies in sampling with regard to capability for detect-
ing impacts on groundwater quality from specific potential
pollution sources (e.g., problems of well location, well com-
pletion, sampling frequency, constituents sampled, sampling
methods, etc.).
Items identified in each of these two categories are discussed in this sec-
tion. Several important monitoring deficiencies in Category 1 have been
identified in the initial stages of this study. Because of these and because
such information is needed to design cost-effective monitoring programs, dis-
cussion of Category 2 deficiencies must be considered preliminary.
180
-------
WELL: a <
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uj S
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o o
UJ
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ca
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CT)
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ta
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: L-5
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-
oo
Figure 9-9. Intervals of perforation of wells on tract C-a.
-------
Monitoring Design Information Base
The methodology being implemented in this study is based on the philoso-
phy that cost-effective monitoring programs can be developed by following a
sequence of steps identifying and characterizing potential pollution sources
and evaluating the mobility of potential pollutants in a specific hydrogeo-
logic framework. Background data for this study are summarized in Sections 1
through 6 of this report. The assessment of mobility potential is considered
in Section 7. Several deficiencies have been noted during the review and de-
velopment of this information summary. Addressing these deficiencies will be
the initial focus of the prel iminary monitoring design program developed in
this phase of study. This will allow a more complete assessment of potential
pollutant mobility, ranking of potential pollution sources, and assessment of
MIS operational monitoring requirements. Information deficiencies with regard
to tract development plans, characteristics of potential pollution sources,
hydrogeologic framework, existing water quality, and potential pollutant mo-
bility are considered in the following paragraphs.
Tract Development Plans-
Uncertainties with regard to the details of MIS development plans are as
follows:
1. Methods to seal MIS retorts (e.g., injection of surface pro-
cessed shale)
2. Flow, treatment, and disposition of retort water
3. Collection schemes, treatment, and disposition of mine water
4. Details of other dewatering (via wells) operations
5. Details of reinjection and other disposal operations.
Characteristics of Potential Pollution Sources--
Uncertainties within this information category are as follows:
1. Sealing of in-situ retorts as a result of:
a. Maintaining the integrity of impermeable layers above and/
or below the retort zone
b. High retorting temperature sealing action on shale minerals
c. Injection of surface retorted spent shale or other sealing/
grouting materials
2. Integrity of rock between adjacent MIS retorts
182
-------
3. Concentration of condensed shale oil, retort water, or other
potential pollutants in the bottom of MIS retorts
4. Chemical characteristics of MIS processed shale leachate from
native groundwaters and rates of leaching
5. Chemical characteristics of MIS retort water
6. Leaching characteristics of surface-retorted spent shale if
reinjected as a slurry
7. Plans for sampling composition of sources (mine water,
dewatering-reinjection well water, retort water, in-situ
spent shale).
Hydrogeologic Framework and Existing Water Quality—
Of key importance for the assessment of mobility of pollutants and for
the design of operational monitoring programs (e.g., well placement, well
construction, and sampling requirements) is knowledge of the hydrogeology and
existing water quality of the study area. Several deficiencies have been
noted in the understanding of this complex groundwater sys-tem. Because great
spatial variability in the hydrogeology has been indicated, satisfying data
needs should focus on the proposed retort fields:
1. Identification and characterisation (hydraulics and water
quality) of individual stratigraphic layers:
a. Isolation of layers using packers for testing and sampling
b. Identification and testing of corresponding (i.e., contin-
uous) intervals in a series of wells to assess area! vari-
ation of hydrogeologic characteristics and water quality
c. Comparison of available data on well bore production, con-
ductivity, temperature, and velocity logs with lithologic
logs to better define zones of water production and quality
2. Investigate nature and extent of upward leakage in northeast
corner of Tract C-a
3. Investigate effects of faults as both hydraulic barriers and
as routes of interaquifer connection (this particularly for
Upper Aquifer on Tract C-a)
4. Sampling proposed (if any) during shaft sinking and lateral
development to examine three-dimensional distribution of
groundwater quantity .(and possibly quality)
5. Examine vertical head gradients and relationships
183
-------
6. Determine leakance values for confining beds
7. Delineate fracture patterns and location of solution openings
8. Further characterize water quality through examination of, for
example, chemical equilibria, stable isotopes, water tempera-
ture variations
9. Evaluate influence of alternative sampling methods (bailing,
swabbing, pumping) and casing material (e.g., steel) on water
quality data
10. Identify rate and direction of groundwater flow.
Potential Pollutant Mobility--
The uncertainties and data deficiencies presented in the preceding para-
graphs result in incomplete capability for predicting the mobility of poten-
tial pollutants. The preliminary assessment is that important attenuation
(e.g., sorption and precipitation) may occur within the retort zone. Attenu-
ation within the existing aquifer zones, however, may not be extensive. Flow
pathways, leaching rates, and the characteristics of potential pollutants are
among the basic incomplete data sets which have been identified. In addition,
the importance of the various attenuation mechanisms outlined in Section 7 is
unknown. Addressing such .unknowns is the purpose of initial monitoring and
testing efforts. Consideration of attenuation mechanisms is an important
factor in assessing the utility of tracer or indicator chemical constituents
as part of monitoring programs. This topic is discussed in more detail in
Section 10 (Monitoring Approaches). Monitoring needs would include:
• Sampling groundwater quality within and adjacent to the retort
zone
• Measurement of hydraulic and water quality gradients within the
retort zone (e.g., between retort and aquifer zones and between
adjacent retorts)
• Using these data to identify important attenuation mechanisms,
particularly those which may be purposefully enhanced.
Related to the assessment of attenuation is the monitoring of the rate
and direction of transport away from in-situ retorts. Monitoring these pro-
cesses will be associated with the hydrogeologic characterization of the re-
tort field as discussed earlier.
Existing or Proposed Monitoring Plans
Existing or proposed monitoring plans for Tracts C-a and C-b, as well as
for the Piceance Basin in other areas, are summarized earlier in this section.
Subsequent discussions have presented uncertainties in the data base needed
for the design of a successful monitoring program. Because of these uncer-
tainties, identification of deficiencies in existing or proposed monitoring
184
-------
plans cannot be made in detail. However, as previously noted, some questions
have been raised relative to the topics of well completion and sampling pro-
cedure. Potential investigations include:
1. Assessment of pumped versus bailed and/or swabbed samples from
alluvial wells and from deep wells on tract or elsewhere in
the basin
2. Assessment of well completions previously used as to the im-
pact on water quality (this is related to characterization of
individual strati graphic intervals as outlined above)
3. Plans to monitor the mine or within abandoned retorts
185
-------
SECTION 10
MONITORING APPROACHES
From the preceding discussions, appreciable uncertainties exist with
regard to prediction of the impact of MIS retorting on groundwater quality.
Major issues relate to:
• Characterization of potential MIS pollutants
• Characterization of mobility pathways and rates, especially
within and directly adjacent to the retort interval
• Sampling methods, including well construction and sample collec-
tion procedures
• Selection of constituents for monitoring MIS sources.
POTENTIAL POLLUTANTS
The major focus of characterization efforts will be leachates from in-
situ spent shale and other residuals (e.g., retort water) remaining in the
MIS retort zone after completion of retorting. Although some data from lab-
oratory simulations are available and have been utilized in this study, the
applicability of these data to actual MIS operations is unclear. Thus, actual
sampling and analysis of MIS retorts are needed. Approaches to address this
information requirement are as follows:
• Core or otherwise sarcple the following for physical and chemical
analysis:
— Proposed retort sealing or stabilizing
— In-situ spent shale (examine variability as related to varia-
tions in raw shale from the interval retorted and variations
in retorting history)
— In-situ retort water
• Perform mass balance inventory for retort water
— Evaluate presence of retort water residue in spent retort
186
-------
• Evaluate water from mine (compare water quality and quantity
near retort before and after retorting)
• Perform leaching experiments with groundwaters of both aquifers
in study area to examine rates of leaching and adsorption/atten-
uation mechanisms. These experiments need to approximate, to
the extent possible, time frames (i.e., long) and flow rates
(i.e., slow) anticipated in retort zone
• Controlled backflooding of a spent MIS retort cell with analysis
of the following:
— Movement into adjacent wells (measurement of head levels,
flow rates, water quality, and evaluation of pollutant
attenuation)
— Hydraulic characteristics of MIS retort
~ Water quality gradients and attenuation within retort zone.
Only the first four of these approaches (sampling within spent retorts and
performing leaching experiments) seem feasible. The backflooding experiments
would clearly provide the truest test, but the engineering design and control
of such an experiment would appear to be prohibitively expensive, even if the
experiment were shown to be physically possible.
HYDROGEOLOGIC CHARACTERIZATION
Study Needs
Hydrogeologic studies to date have been largely regional in focus. This
has led to a largely regional focus in monitoring plans rather than a near-
field, source-specific monitoring orientation, which is more appropriate for
pollution detection and control purposes. The indicated great spatial varia-
bility in hydrogeologic and water quality characteristics of the study area
has resulted in data sets collected to date which may not be applicable to
source-specfic monitoring designs (i.e., within and particularly immediately
downgradient from the MIS retort fields).
Evaluation of potential mobility pathways requires:
• Detailed analysis of the near-field (relative to MIS retorts)
fracture system
• Analysis of three-dimensional variability of hydrogeologic
characteristics
• Evaluation of the effects of dewatering, reinjection, retort
development, and retort operation on the hydrogeology.
Some approaches for addressing the analysis needs follow:
187
-------
• Geophysical methods
— Reanalysis of data from tract exploration phases (not included
in environmental baseline reports) to evaluate utility for
examination of porosity within retort fields
-- Potential for additional logging in existing core holes or
we! 1 bores
-- Geophysical logging of new wells proposed for Tract C-b re-
tort field (methods outlined in following discussion)
• Analysis of dewatering (Tract C-a) data (pumping and reinjection)
— Treat as large-scale aquifer test with close-in orientation
to retort field
-- Evaluate water quality data (particularly variations in water
withdrawn from different intervals in aquifer zone)
• Examination during mine excavation
— Examination of fractures near retort interval
— Sample water flow and water quality within mine (pre- and
post-retort detonation)
— Possibly coring within mine near retort (e.g., from upper
sublevels)
• Further evaluate potential for upward leakage in northwest cor-
ner of Tract C-a
• Development of anisotropic flow nets for Upper and Lower (above
and below retort zone) Aquifer zones
* Outline testing methods for confined beds (leakance), vertical
head gradients, investigation of faults as hydraulic barriers or
pathways.
Baseline Data Acquisition
Because of the complex nature of the hydrogeology and geochemistry of
the natural groundwater system in the Piceance Basin, considerable additional
knowledge will have to be obtained at each specific mining site to allow pre-
liminary estimates of contaminant flow rate and direction to be made and to
allow preliminary design of the monitoring system. The required information
includes:
1. Delineation of the individual porous and permeable zones, their
thicknesses, porosities, permeabilities, potentiometric sur-
faces, natural water quality, and area! extents
188
-------
2. Definition of the individual confining layers and their
properties
3. Definition of structural geologic features that affect the
hydrogeologic system
4. Location of the discharge points for each aquifer (or aquifer
unit).
It appears that, in spite of the effort that has already been made to
acquire site-specific hydrogeologic data, the information sets listed above
are not complete. The field studies that have been performed do, however,
establish a basis for design of the more detailed analyses that are needed.
Definition of Individual Porous and Permeable Zones—
Although it has been concluded that, in general, two rock aquifer sys-
tems (a shallow and deep one) are present in the Piceance Basin, available
evidence shows that the hydrogeology is actually more complex. It appears
that porous and permeable intervals exist locally which may or may not be
hydraulically interconnected and may or may not conform to the general con-
cept of an Upper and a Lower Aquifer with the Mahogany Zone as the aquielude
between the two. It is extremely difficult to completely address the adequacy
of models or groundwater monitoring systems at a specific mining site in the
Piceance Basin until the principal porous and permeable zones have been iden-
tified locally and their hydraulic properties, potentiometric surfaces, nat-
ural water qualities, and areal geometries determined to the extent possible
and practical.
In the Piceance Basin, initial identification of porous and permeable
zones can probably best be accomplished by downhole methods. Examination of
rock units at the outcrop may be of some help, but would not be sufficient
alone. The only applicable remote method would be seismic reflection, which
can, under the proper conditions, be used to identify and map porous zones.
It is judged that conditions in the Piceance Basin are not conducive to the
use of seismic reflection for porous zone identification. It might be applied
experimentally for areal mapping after identification of such zones by down-
hole methods.
Downhole methods for identification of porous and permeable zones
include:
1. Core drilling
2. Rock drilling
3. Bore hole geophysical logging
4. Injectivity and pump testing
5. Water-level measurements and water sampling.
189
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Core drilling—Drilling of small-diameter core holes is a relatively
inexpensive method of locating and characterizing porous zones. Cores can
reveal fractures, solution features, and evaporite zones that are subject to
solution activity. It is possible that none of these might be recognized in
holes drilled with rock bits. Core drilling was performed at each tract in
the exploration phase. Cores are sometimes retained and may still be availa-
ble for inspection. If not, core descriptions may alternatively be available.
If neither cores nor descriptions are available, new core drilling at a few
selected locations may be worthwhile.
In addition to visual examination, cores can be laboratory tested for
porosity, permeability, and other engineering properties. However, labora-
tory testing of cores taken from aquifers with major fracture or solution
porosity and permeability is of little value.
Rock drilling--Information on the location of porous and permeable zones
can, possibly, also be obtained during drilling of bore holes with rock bits.
During rock-bit drilling, the presence of such zones is indirectly indicated
by influxes of water, loss of drilling fluid, changes in drilling rate, change
in fluid level in the bore hole,
already been drilled might yield
and permeable zones.
etc. Drillers' logs for bore holes that have
some information on the presence of porous
In any case, as new holes are drilled, the drillers should be encouraged
to note such occurrences as are mentioned above.
Bore hole geophysical
ging tools
zones.
are commercially available that
These include:
logging--A variety of bore hole geophysical
useful in defining
are
log-
porous
1. Electrical logs
2. Elastic wave logs
3. Radiation logs
4. Other logs.
The particular logs in each of the categories that detect porosity are
noted in the applications column of Table 10-1. It is of particular interest
that elastic wave logs can differentiate between fracture or solution poros-
ity and intergranular porosity.
In addition to the logs listed in Table 10-1, such miscellaneous logs as
caliper logs, dipmeter logs, and production-injection logs may be used.
Production-injection logs are logs normally run through tubing or casing af-
ter a well is completed. Some of these logs are the same as listed in Table
10-1, but a number of specialized logs are also used.
The principal
tion of:
applications of product!on-injection logs are determina-
190
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TABLE 10-1. GEOPHYSICAL WELL LOGGING METHODS AND THEIR APPLICATIONS
Method
Property
Application
Electrical Logs
Spontaneous
Potential (SP)
Electrochemical and elec-
trokinetic potentials
Nonfocused electric Resistivity
Focused conductivity Resistivity
Focused resistivity Resistivity
Focused and non-
focused micro-
resistivity
Resistivity
Elastic Wave Propagation Logs
Transmission
Reflection
Compressional and shear
wave velocities
Compressional and wave
attenuations
Amplitude of reflected
waves
Formation water resistiv-
ity (Rw)> shales and
nonshales; bed thickness;
shaliness
a. Water and gas/oil
saturation
b. Porosity of water zones
c. Rw in zones of known
porosity
d. True resistivity of
formation (R-{-}
e. Resistivity of invaded
zone
a, b, c, d.
Very good for estimating
R.J- in either fresh water
or oil base mud
a, b, c, d.
Especially good for deter-
mining Rt of thin beds
Depth of invasion
Resistivity of the flushed
zone (RXQ) f°r calculat-
ing porosity
Bed thickness
Porosity; lithology,- elas-
tic properties, bulk and
pore compressibilities
Location of fractures;
cement bond quality
Location of vugs, frac-
tures; orientation of
fractures and bed boun-
daries; casing inspection
(continued)
191
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TABLE 10-1 (continued)
Method
Property
Application
Radiation Logs
Gamma ray
Natural radioactivity
Spectral gamma ray Natural radioactivity
Gamma-gamma
Neutron-gamma
Neutron-thermal
neutron
Neutron-epithermal
neutron
Pulsed neutron
capture
Spectral neutron
Other Logs
Gravity meter
Ultra-long spaced
electric
Nuclear magnetism
Temperature
Bulk density
Hydrogen content
Hydrogen content
Hydrogen content
Decay rate of thermal
neutrons
Induced gamma-ray
spectra
Density
Resistivity
Amount of free hydrogen;
relaxation rate of
hydrogen
Temperature
Shales and nonshales;
shaliness
Lithologic identification
Porosity, lithology
Porosity
Porosity; gas from liquid
Porosity; gas from liquid
Water and gas/oil satura-
tions; revaluation of old
wells
Location of hydrocarbons;
lithology
Formation density
Salt flank location
Effective porosity and
permeability of sands;
porosity for carbonates
Formation temperature,
flow direction, relative
head
1. The physical condition of subsurface equipment and the bore
hole
2. The location of production or injection zones
3. The quantity of fluid produced from or injected into a par-
ticular zone
4. The results of well bore stimulation treatment.
Table 10-2 lists some of the available production-injection logs that
would have particular application to porous zone identification.
192
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TABLE 10-2. SELECTED PRODUCTION-INJECTION LOGS AND THEIR FUNCTION
Log
Function
1. Gamma-ray
2. Neutron
3. Bore hole televiewer
4. Flowmeter (spinner logs)
5. High-resolution thermometer
6. Radioactive tracer
7. Fluid sampler
8. Fluid pressure
Determine lithology and presence of
radioactive tracers through casing
Determine lithology and porosity through
casing
Provide an image of casing wall or well
bore
Locate zones of fluid entry or discharge
and measure contribution of each zone to
total injection or production
Locate zones of fluid entry including
zones behind casing
Determine travel paths of injected
fluids including behind casing
Recover a sample of well bore fluids
Determine fluid pressure in bore hole at
any depth
Bore hole logs that have been run in some of the holes already drilled
should be obtained and interpreted. Bore holes not previously logged could
possibly be logged. Where holes have been steel cased, only radiation logs
could be run in the cased portion. Where holes are PVC cased, electrical in-
duction logs could probably also be run in the cased portion of the hole. The
particular suite of logs to be run would be dictated by economics as well as
technical considerations and would need to be determined in consultation with
logging service company representatives.
Injectivity and pump testing—Some aquifer testi
Oil Shale Tracts C-a and C-b.Additional tests shoul
porous and permeable zones, rather than on the gross
tested previously. In preparation for testing, the i
be isolated with packers. Monitor wells should also
selectively set to test the continuity of individual
zones and the extent of their hydraulic interconnect!
zones. The alternative to using packers would be to
tap the zone to be tested.
ng has been performed at
d be made on individual
intervals- that have been
ndividual zones should
have temporary packers
porous and permeable
on with other adjacent
construct wells which
The details of any such testing program will have to be determined after
the number, location, thickness, and continuity of the porous zones have been
estimated from the other procedures suggested above.
193
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Hater level measurements and water sampling—In an undisturbed state, it
is quite probable that individual porous and permeable zones had differing
hydraulic heads, hydraulic gradients, flow patterns, and water qualities.
These characteristics can allow differentiation among zones and tracing of
zones. However, it may be difficult or even impossible to reconstruct the
original natural conditions for the individual zones because of the amount of
interconnection that has occurred as a result of bore holes left open to mul-
tiple zones. Any available data should be used in an attempt to depict the
most probable undisturbed hydrologic conditions. It may be desirable to mod-
ify existing monitoring wells to isolate certain porous and permeable zones.
This might allow the hydraulic conditions in such zones to readjust to the
original or near-original conditions and would, in any case, permit monitor-
ing of discrete intervals rather than multiple intervals. Multiple zones can
be monitored in a single well by use of multiple tubing strings and packers.
A central issue related to the isolation and individual consideration of
permeable strata is the scale of this segmentation in a given well design.
In other words, at what point do differences in hydraulic or water quality
characteristics become significant enough to justify the added expense of
multiple completions? At the time of drilling and testing, data can be com-
piled on gross properties of the well location via use of, for example, dril-
lers' logs, geophysical logs, temperature logs, conductivity measurements,
and spinner logs. Data for a series of wells could be collected and compared
to identify intervals to be isolated and to obtain consistency between moni-
tor well completions. Further evaluation using injection or pumping tests
could be used to finalize the completion schemes. Leaving drilled holes open
during this testing and the evaluation process should present no great diffi-
culties in these hard-rock aquifer zones.
These considerations are relevant both to deep aquifer wells and to
alluvial aquifer wells. The heterogeneity of deep fractured aquifers is de-
scribed elsewhere in this report. Significant variability can also be found
in alluvial systems. Varying characteristics of alluvial strata can create
significant differences in water quality as well as head differences between
layers. As with evaluation of deep aquifer well construction, such factors
must be carefully considered at each site (or set of well sites) to judge
whether it is appropriate or desirable to composite samples over these inter-
vals or if the different intervals should be isolated for separate monitoring.
Properties of Confining Layers—
Just as individual porous zones require more accurate characterization,
the individual confining layers should be located and their thicknesses, ver-
tical permeabilities, and lateral extents determined. The procedures will,
in general, be the same as those used to define the porous zones except that,
during pumping or injection testing, the confining layers are indirectly
tested at the same time that the porous zones are being directly tested.
Therefore, separate field tests will not normally need to-be performed upon
the confining layers.
194
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Structural Geologic Features—
Local geologic structure can greatly affect the groundwater hydrology.
Faults and fracture zones can act as flow conduits and, on the other hand,
faults may cut off porous zones and act as hydrologic barriers. Such struc-
tural features are best located by surface and subsurface geologic mapping.
The hydrologic effect of geologic structures can be determined by water-level
information which is used to construct potentiometric surface flow nets. Po-
tentiometric surface flow nets can reveal the presence of flow conduits or
barriers through the configuration of the flow lines. Pump tests or injec-
tion tests can directly determine the hydraulic effectiveness of faults or
fracture zones to act as flow conduits or of faults to act as flow barriers.
Such tests must, however, be designed so that these features will exert a
measurable hydraulic effect during the performance of the test.
Aquifer Discharge Points—
To assess the environmental impact of contaminants introduced into the
groundwater system by in-situ oil shale combustion, it will be important to
locate points at which discharge to surface waters occurs. Discharge points
importantly influence the flow pattern and flow velocity in the discharging
aquifer. Furthermore, if it can be predicted that contaminants will be dis-
charged to a surface water while still in an undesirable form and concentra-
tion, then the contaminants may be viewed differently than if they were to
remain contained indefinitely in the subsurface.
Discharge points are located by surface reconnaissance, stream gaging,
seepage-salinity surveys, mapping of aquifer water levels, and possibly by
introduction of tracers into aquifers and following them to discharge points.
SAMPLING AND ANALYSIS
The facets of monitoring considered under this heading include sample
collection methods, selection of constituents for analysis, and data
presentati on-eval uati on programs:
• Compare data obtained from pumping, bailing, and swabbing of
deep wells (assess costs as well as data collected)
• Assess influence of Tract C-b well recompletions on water qual-
ity (and water-level) data
• Assess influence of casing materials, if possible
• Select constituents for monitoring (testing associated with
leaching tests)
— Use of tracers
-- Evaluate enrichment factors
— Stable isotopes as tracers
195
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* Assess physical access for monitoring within spent retorts
— Access through bulkheads
— Use of piping from retorting operation
• Assess "survival" of water quality samplers (e.g., salinity sen-
sors, porous cups, etc.) in retort environment (this testing is
associated with leaching tests)
• Evalute and test sample-handling procedures (e.g., effects of
holding time on analysis results)
* Recommend data-handling methods useful for easy presentation and
assessment
* Conduct lab analyses (particularly for process streams, such as
retort waters).
Source Monitoring
As noted earlier, groundwater quality monitoring should have a source-
specific focus. Needs for monitoring of in-situ retorts, retort water, and
dewatering-reinjection, as observed on Tracts C-a and C-b, are outlined below.
In Situ Retorts (Spent Shale) —
below.
section.
Preliminary monitoring recommendations for the in-situ retorts are listed
'. Selection of constituents for sampling is considered later in this
• Evaluate use of existing wells or core holes, including possible
well recompletions to monitor specific zones of permeability
around retort fields
Major disadvantage is that many wells developed for Tract C-a
and C-b baseline studies are at some distance from individual
retorts or retort fields and hence are the not best sites for
monitoring retorts
• Need to sample all significant aquifer units in the vicinity of
retorts (e.g., five units were identified for Tract C-b; the
Uinta Aquifer has recently been included in an Upper Aquifer
unit)
• Need wells in and immediately downgradient from retort fields
(neither tract seems well set for this recommendation)
• Need wells which tap retorts themselves. Access may be from
within mine or from surface, the former probably being least
expensive. Some risk of aquifer interconnection via well bore
is possible with such wells.
196
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Retort Water--
Alternatives for monitoring retort water are as follows:
• Monitor volume produced
— Monitoring via in-line flowmeters or sonic-type devices (the
latter are probably a better choice because of potential
maintenance problems with mechanical devices).
— Monitor at various points (inventory to keep track of retort
water): production point (retort), treatment point (if
treated), storage site, disposal site. This will not, how-
ever, indicate anything about residues condensed and remain-
ing within retorts.
— Monitoring can be continuous or periodic (at least for ini-
tial operations, the former is preferable).
• Monitor chemical quality
-- Monitor changes at various points (production, treatment,
storage, disposal)
— Perform mass balance inventory
— Evaluate use of specific "tracer" constituents or indicator
variables
— Evaluate lab methods for analysis.
• Assess variability of retort water flow and quality to define
sampling frequency (e.g., use continuous monitoring of flow,
conductivity, and pH with more complete analysis on weekly or
daily interval). Some such data may be available from Logan
Wash where retort waters are sampled daily.
• Assess flow and water quality variability between retorts.
Mine Water/Dewatering—
Monitoring of mine water and dewatering/reinjection systems includes
both within-the-mine and well monitoring components. Many of these sampling
programs are related to area hydrogeologic and water quality assessments dis-
cussed earlier:
• Monitoring of in-mine collection systems
— Flow rates from different parts of the mine
-- Water quality from different parts of the mine
197
-------
— Sample during mine shaft and mine lateral and sublevel
construction
• Dewatering/reinjection wells
— Initial analysis to evaluate mass balance and flow
— Follow area water levels to further evaluate hydrogeology
(e.g., assess fractured intervals, perched zones, etc.).
The monitoring approaches appropriate for disposal well systems are pre-
sented below (from Warner, 1975). Two major approaches are outlined: moni-
toring the injection well itself and using outlying monitoring wells. The
latter may be the most appropriate. The injection well itself may be the
most likely route of unexpected release of injected water:
• Surveillance of injection well
-- Allow estimates of distance of injected water travel (from
well pressure (head) and hydraulic properties of injection
zone)
— Interpretation of pressure data
-- Record of injection activity
• Quality of injection water
-- Continuous, perhaps suspended solids, pH, conductivity, tem-
perature, dissolved oxygen
-- Composite or grab samples periodically for more complete
characterization
• Injection pressure-record of reservoir performance
— Continuous monitoring (want to avoid hydraulic fracturing,
damage to well facilities)
— Collect and evaluate pressure fall-off data to check reser-
voir performance
• Pressure in casing-tubing annulus
-- Changes may indicate leakage through injection tubing or
packer systems
-- Use conductivity probe to check chemistry of casing-tubing
annulus to check for leaks
• Periodic inspection and testing
198
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— Casing, tubing cement
• Pull tubing (visual or instrument inspection)
• Use logs to inspect in place (e.g., magnetic logs for
relative pipe thickness; televiewer logs for visual inspec-
tion; or caliper logs for plugging or enlargement of casing)
— Inspect casing cement with cement bond or temperature logs to
detect channels in cement behind casing
— Inspect casing, cement, or well bore with injectivity or tem-
perature profiles or tracer injectivity profiles to detect
where injected fluid is going
• Monitoring wells
-- Monitor pressure in receiving aquifer; pressure at a known
distance may be of concern due to suspected faults, poorly
plugged abandoned wells, or other unaccounted for pathways of
release of injected waters
— Useful for verifying rate and direction of flow of injected
water or geochemical changes due to injection program
-- Useful to monitor pressure changes within confining beds or
in a confined aquifer immediately above confining bed when:
• Confining beds are relatively thin
• Aquifer properties are such that pressure responses will
be rapid if leakage occurs (slow vertical leakage through
multiple fracture layers in oil shale area may reduce util-
ity of this approach)
— Use monitoring wells in overlying (relatively good quality)
aquifer to detect water quality changes (best placement is
close to injection well(s) and near other deep wells or near
fault or fracture zone which may be vertical flow paths for
injected water).
Warner (1975) also notes that the injection well itself may be modified to
sample overlying aquifers through the use of multiple completions in the same
well.
Factors Affecting Sampling
The methodology being used in this study provides a logical framework
for design of groundwater quality monitoring programs, including selection
of sampling sites, well construction features, sample collection methods,
and sampling frequency. In the oil shale regions, the complexity of the
199
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hydrogeologic systems encountered can present some special problems with re-
gard to these monitoring components.
Sampling Sites—
Groundwater flow in the Piceance Creek Basin occurs in several complex
systems of fractures and faults. The evaluation of a fractured-rock flow
system is generally much more complicated than assessment of a granular, por-
ous media type of aquifer system. In fractured-rock systems, even defining
the direction of flow may not be straightforward. Generally, the direction
of flow and the flow gradient in groundwater systems are identified by mea-
suring the head (or water level) in a set of wells and estimating lines of
equal head. Flow then is perpendicular to these equipotential lines (Figure
10-1). However, flow in fractured rock is along fractures and these flow
paths can provide a flow direction which is nearly perpendicular to that
which may be estimated from simple observation of head levels (Figure 10-2).
Using this illustration (Figure 10-2), placing a well at point B to monitor
the effects of an injection well or other waste source at point A would
clearly not produce data which address the defined information requirements.
The need for detailed hydrogeologic evaluation is thus an integral part of
the monitoring design methodology.
400
395
HEAD ELEVATION
390 385
375
EQUiPOTENTIAL
FLOW (ORTHOGONAL)
Figure 10-1. Sample of groundwater flow net.
200
-------
INFERRED DIRECTION
V
GROUNDWATER
CONTOURS
\
\
X^FRACTURES
ACTUAL
DIRECTION
Figure 10-2. Idealized two-dimensional pattern showing the relation between
true direction of groundwater flow and the direction inferred
by drawing orthogonal lines to the regional water-level con-
tours (adapted from Davis and DeWeist, 1966).
Well Construction—
The aquifer systems in the Piceance Basin include a series of horizontal
fracture sets very irregularly interconnected by vertical fractures and
faults. The system has commonly been portrayed as including two aquifers
separated by the rich oil shale beds of the Mahogany Zone. In actuality, the
irregular spacing of both vertical and horizontal fractures, the. appreciable
variability of hydraulic properties among these fracture sets, and the vary-
ing degrees to which halite and nahcolite minerals have been leached from
different zones create numerous distinct aquifer units. Where wells are
located and where they are perforated (open to water-bearing zones) have a
significant influence on the data collected. This is true for data on both
aquifer characteristics and groundwater quality.
Consider, for example, two wells located close together and which are
perforated over exactly the same interval. The perforated interval contains
two fractured strata of equal hydraulic conductivity (Figure 10-3). One
stratum contains abundant saline minerals and the other little. One well
intersects a fracture in the upper stratum but none in the lower (saline
stratum), while the other intersects a fracture in only the lower stratum.
These two wells will provide drastically different water quality data in
spite of their proximity and construction similarity.
201
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LOWTDS
WATER WELL
HIGH TDS
WATER WELL
GROUND SURFACE
UPPER FRACTURE STRATA,
LITTLE SALINE MINERALS
Figure 10-3.
LOWER FRACTURE STRATA,
SALINE MINERALS PRESENT
Fractured-rock aquifer system yielding water of varying
quality depending on location and perforation of wells.
This situation may be further complicated by varying permeabilities of
different strata. Some fine-grained, high-organic-level strata are resistant
to fracturing and may form effective aquitards. This can result in different
head levels between layers and mixing of highly different quality waters in
interconnections, such as well bores. As an example of how well completion
(and recompletion) can affect water quality data, consider the following data
reported for Tract C-b (C-b Shale Oil Venture, 1977b).
Original well
designation
SG-11-1
SG-10
SG-17-1
TDS before
recompletion
39,000
42,000
28,000
TDS after
recompletion
16,000
2,800
4,300
New well
designation
SG-11-1R
SG-10R
SG-17-1R
These wells had initially encountered, and had been open to, a highly saline
water zone which apparently had a higher hydrostatic head than less saline
overlying aquifer zones. Thus, water collected from these overlying zones
was affected by the interconnection. Recompletions were undertaken to iso-
late these different water quality zones.
202
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Also, interval of completion and perforation may affect water-level data.
For example, on Tract C-b, an apparent mound of water in the center of the
tract may be due to data from a well (SG-6) completed over a small segment of
the aquifer zone. If this interval has a high head, then this well will show
a greater head level than other wells in the area which are perforated over a
wider zone and thus exhibit a more average head.
Sample Collection Methods--
Methods currently being used to collect groundwater samples on the oil
shale tracts include bailing, swabbing, and pumping. The choice of sampling
method can greatly influence the results of water quality sampling and thus
the interpretation of monitoring data.
On Tract C-a, all groundwater quality samples are collected by bailing.
Sufficient water is bailed to fill the required sample bottles. One of the
goals of sampling is to obtain water quality data which are representative of
water within the aquifer zone being sampled. Aside from problems of well
completion, bailing of a small volume from a well bore may not provide the
desired representative sample. For example, construction of deep wells may
include a perforated zone of perhaps 300 feet. A 6-inch casing, 300 feet
long, contains about 450 gallons of water. If approximately 4 gallons are
bailed for sampling, for example, on a quarterly basis, water sampled may not
be representative of local groundwater, but rather of water which has been
standing in the well bore (perhaps a very different physiochemical environ-
ment) for some time.
The implication here is that care must be taken with the use of bailing
as a sampling technique. For example, tests conducted by Rio Blanco Oil
Shale Project (Tract C-a) indicated that samples bailed from well intervals
perforated in aquifer zones produced results very comparable to pumped water
samples. However, samples bailed from the well interval above the perforated
zone (and where water is stagnant within the well) yielded water quality data
quite different from either pumped samples or samples bailed from the aquifer
zone.
Swabbing, which is used to collect samples from deep aquifers on Tract
C-b, includes the use of oil field equipment to collect water samples. Sev-
eral swabbing runs, removing the water column from the well bore, are made
prior to collection of samples for laboratory analysis. This approach may
provide water quality samples more representative of local aqu-ifer conditions
than bailing, as several well volumes are removed prior to actual sample
collection.
Care must also be taken with the swabbing techniques so that contamina-
tion of samples (such as from organics from the oil field equipment) does not
occur. In addition, the swabbing action may accelerate the plugging of well
perforations by the action of the rubber swabbing cup on the casing. The
amount of water swabbed from a well must be carefully considered to obtain
consistent and representative samples. Variations in water quality (conduc-
tivity) observed during swabbing are shown in Table 10-3.
203
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TABLE 10-3. RANGE OF CONDUCTIVITY OBSERVED AND FINAL CONDUCTIVITY
LEVEL OF SWABBED SAMPLES, TRACT C-b, FALL 1976
Well/string
number
S6-1-1
SG-1-2
SG-9-1
SG-9-2
SG-21
Cb-4
SG- 11-12
SG-11-2
SG-11-3
SG-18A
Cb-2
SG-6-1
SG-6-2
SG-6-3
Gallons
swabbed
1,260
2,840
2,100
1,150
3,210
2,300
1,220
530
300
—
2,920
550
630
160
Observed
conductivity
range
(umhos/cm)
3,000
1,200
1,300
1,850
750
800
14,000
800
1,600
750
1,600
1,800
1,300
1,350
- 10,000
- 1,500
- 3,400
- 2,100
- 1,150
- 900
- 32,000
- 4,000
- 1,800
- 1,250
- 1,650
- 3,100
- 1,400
- 1,550
Final
conductivity
(umhos/cm)
8,250
1,250
2,000
1,850
1,000
825
22,000
1,200
1,790
1,000
1,600
3,000
1,300
1,550
Many of the difficulties of obtaining representative samples by bailing
or swabbing are overcome by use of a submersible pump to collect samples. By
pumping, a relatively large area of the aquifer is sampled rather than a zone
within or immediately adjacent to the well bore. This "sampled zone size" is
an important consideration for monitoring purposes, as well as for general
collection of representative samples. For example, assume a well is perfor-
ated throughout the water-bearing zone (Figure 10-4). Bailing will sample
essentially the width of the well bore, perhaps 6 or 8 inches of the aquifer
cross section. Swabbing would sample a wider cross section (perhaps a few
feet) and pumping the widest cross section (perhaps several tens of feet).
Obviously, the opportunity of detecting the mobility of potential pollutants
is enhanced by sampling a greater cross section of the aquifer.
Care must also be taken in the design of sampling programs which include
pumping. As shown in Table 10-4, water quality can vary greatly as pumping
continues. A schedule of pumping time before sample collection has to be es-
tablished, largely by trial sampling of each well and frequent sampling of,
for example, conductivity and pH, in the field during pumping.
204
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MONITOR WELL
BAILING-
SWABBING
PUMPING
Figure 10-4.
LAND SURFACE
WATER TABLE
Schematic of size by aquifer cross section sampled by bailing,
by swabbing, and by pumping of monitor well.
TABLE 10-4.
FLUORIDE AND BORON FROM LOWER AQUIFER
TEST (C-b Shale Oil Venture, 1977b)
Date (1975)
January 20
February 5
February 23
February 24
February 25
February 27
February 28
March 1
March 3
March 5
March 7
March 19
Fluoride
(ppm)
18.0
18.1
20.0
20.1
20.4
18.4
20.4
20.2
19.0
20.0
21.2
23.2
Boron
(ppm)
0.65
0.88
1.15
1.10
1.13
1.2
1.6
1.42
2.58
2.02
2.18
2.00
205
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A good data base to evaluate the cost-effectiveness tradeoffs of alterna-
tive sampling methods has not been developed. Various cost factors include:
Cost factor
Minimum well size
Sampling gear
Bailing
Crew size (minimum)
Time to collect
sample*
Relatively small
(<3 inches)
Sample (bailer
plus rope or
cable)
— more complex
for deeper
holes
1 to 2 people
Short
Swabbing
Relatively small
(<3 inches)
Special swabbing
rig
Pumping
3 people
Relatively long
>4 inches
Pump, cable,
discharge pipe
or hose, elec-
tric power
source
2 people
Longest
Existing data indicate that these approaches may produce somewhat different
data on water quality. Whether these differences are of importance is unclear
at this time.
Sampling Frequency--
Defining an appropriate sampling frequency is a complex issue influenced
by location of sampling sites, monitoring goals, climatological factors, and
characteristics of groundwater flow. As a result, sampling frequency should
be defined on a case-by-case and likely trial-and-error basis. One of the
key factors is groundwater flow rate. If flow from a potential pollution
source to a monitoring well is expected to be on the order of decades (assum-
ing a release occurs), then very frequent sampling does not seem warranted
and perhaps annual sampling for a few indicator constituents would suffice.
The complexity of the hydrogeology of the oil shale region makes estima-
tion of groundwater flow rate difficult at best and the actual flow rates
highly site specific. Table 10-5 lists some estimates of travel time in the
Upper Aquifer zone of the Piceance Creek Basin. The wide variation in re-
sults reinforces the care needed in design of monitoring programs, as our
understanding of the system is incomplete.
Casing Material —
Casing material (e.g., PVC or steel) can also affect water quality data.
PVC is preferred to avoid contamination of samples with metal casing corrosion
products or adsorption of dissolved constituents onto corroded casing walls.
However, the structural properties of PVC may preclude its use for very deep
wells. Open-hole (uncased) intervals, which are isolated above and below by
* Actual time to collect sample for analysis is
removed from well prior to sample collection.
dependent on amount of water
206
-------
TABLE 10-5. FLOW RATES OF THE UPPER AQUIFER, PICEANCE CREEK BASIN,
ESTIMATED BY THREE STUDIES
Travel time
Flow velocity (years to
Study reference (feet per day) travel 1 mile)
Lawrence Berkeley Labs, 1978
(data from Weeks et al., 1974) 0.05 300
U.S. Atomic Energy Commission,
1972
Knutson, 1973
0.36 - 0.78a
11.7
20 - 40
1.2
aRange for representative gradient and maximum gradient cases.
packers and/or cement seals and which may be assessed by PVC lines, may be one
way of dealing with these problems. Expense of construction and potential for
lodging of equipment (pumps) in the well may, however, limit this approach.
Operational Matters—
Related to sample collection is the analysis of water quality samples in
the field. As described above, sueh analyses (e.g., conductivity and pH) are
a key element of deciding when to collect pumped, bailed, or swabbed samples.
Records of volumes of water withdrawn from a well and water quality data
(perhaps in graphical form) should be utilized by field crews during sampling
operations. This is needed to assure collection of consistent water quality
samples.
Selection of Constituents for Monitoring
The proper location of monitoring points is largely determined by the
locale and character of the potential sources of groundwater quality impact
and the source locale hydrogeology. The constituents for monitoring are se-
lected so as to provide a cost-effective indication of the nature and extent
of impact on groundwater quality. Assessment of enrichment factors (or con-
centration change above ambient), specific indicator constituents, and stable
isotopes are possible approaches for selection of constituents for chemical
analysis.
Enrichment Factors--
In this subsection, enrichment factors, EF, will be calculated for major
possible sources of groundwater impact according to the expression:
concentration from potential pollution source
EF =
concentration in aquifer
207
-------
For this assessment, representative baseline water quality levels were se-
lected (Table 10-6). Concentrations from the more saline sections of the
Lower Aquifer are included principally in Table 10-6 in order to most clearly
demarcate the differences in enrichment factors. Representative concentra-
tions of constituents in retort water and in spent shale leachate were used
in this preliminary analysis.
Also shown in Table 10-6 are the lowest concentrations typically reported
by a Denver water quality laboratory employing standard methods. As can be
seen, the average concentrations of P, V, Ti, As, Se, Ni, Co, Cu, Cd, Br, Be,
Ba, and As are close to or below these lower limits. It is therefore likely
that many of these trace element species were determined by spark source mass
spectroscopy with the associated improvement in detectability, but degrada-
tion in precision in comparison to standard methods.
Table 10-7, which lists enrichment factors for the Lower Aquifer, is
pertinent to the contamination of the Upper Aquifer, springs, and seeps by
the Lower Aquifer. As can be seen, Nfy, K, Na, B, and Br are enriched at
least 10 times in the Lower Aquifer compared to either the Upper Aquifer or
spring waters. In addition, Ba and F are enriched in the Lower Aquifer com-
pared to spring waters. It is likely, therefore, that these species would be
indicators of intrusion of waters from the Lower Aquifer.
Table 10-8 lists enrichment factors for leachates and shows that the pa-
rameters OH (or pH), TDS, Cl, Na, $04, Mo, Se, and TOC are likely indicators
(i.e., tracers) of contamination in the Lower Aquifer. Although carbonate ap-
pears to be enriched in leachate, this reflects an increase in pH rather than
an increase in total HC03 +
Note that these enrichments are consistent with Equations 1 through 9
expected of a calcined product (Section 7). Sulfate is an expected product
of Equation 3. Increased Mo, Cr, and Se are expected from Equations 7 through
9, especially since they form soluble anions under basic, oxiding conditions.
The uncertainty in the enrichment factors reflects variations in the
original oil shale, methods of retorting, and methods of analysis, and empha-
sizes the necessity of preliminary, controlled experiments prior to finalizing
monitoring programs. Enrichment factors for those elements which are present
in concentrations near the detection limit, such as Se, would also be expected
to give variable enrichment factors.
Table 10-9 presents enrichment factors for retort waters and is relevant
to the extent that an in-situ retort is not completely burned and retains a
fraction of the retort water. Most notably enriched in the retort water are
NHj, Oh, As, Br, Co, Hg, Se, V, U, and TOC, and possibly N0§, PO} , and Ni.
The sulfur species shown at the bottom of the table will be discussed in the
next subsection.
Although C0§ is enriched in retort waters, it is unlikely that this spe-
cies would successfully pass through a spent retort because of the reaction:
208
-------
TABLE 10-6. REPRESENTATIVE CONCENTRATIONS IN GROUNDWATERS
ADAPTED FOR THIS STUDY
Gross Parameters (mg/1)
Conductance (pmho/cm)
PH
TDS
Ammonia
Bicarbonate
Calcium
Carbonate
Chloride
Cyan i de
Magnesium
Nitrate
Potassium
Silica
Sodium
Strontium
Sulfate
Phosphate
Kjeldahl nitrogen
Nitrite
Sulfide
Minor and Trace Elements
Aluminum
Arsenic
Barium
Beryl 1 i urn
Boron
Bromine
Springs,
seeps and
alluvial
aquifer
1,300
6-8
900
0.4
500
70
3
10
0.01
70
2
2
20
150
2
350
<0.1
2
0.2
0.2
(pg/D
300
5
50
<100
500
20
Upper
Aquifer
1,500
7 - 8.5
1,000
0.5
500
50
3
10
0.01
70
1.0
2
20
200
2
350
<0.1
—
—
0.6
200
10
100
<10
1,000
50
Saline
Lower
Aquifer
7,000
8
6,000
10
4,000
200
20
20
0.01
20
0.5
20
10
2,500
—
60
<0.1
—
—
0.6
250
10
800
—
40,000
500
Lower
working limit
of detection,
Denver
Labor atorya
2
—
1
100
5
0.05
5
0.2 - 1
0.002
50
0.02
0.1
1
0.1
0.01
3-10
0.1
0.1
0.02
0.1
100
2-50
50
5
50
2,000
(continued)
209
-------
TABLE 10-6. (continued)
Springs,
seeps and
alluvial
aquifer
Upper
Aquifer
Saline
Lower
Aquifer
Lower
working limit
of detection,
Denver
Laboratory3
Minor and Trace Elements (pg/1) (continued)
Cadmium
Chromi urn
Cobalt
Copper
Fluoride
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Radiation, alpha (pCi/1)
Radiation, beta (pCi/1)
Rubidium
Scandium
Selenium
Silver
Thallium
Titanium
Uranium
Vanadium
Zinc
Lithium
Gross Organic Parameters
TOC (mg/1)
Phenol (pg/1)
DOC (mg/1)
COD (mg/1)
17
11
8
30
400
500
50
30 - 500
0.4 - 3
40
30
5
4
10
4
<10
<1
—
200
—
5
200
<100
5
3
5
16
10
2 - 300
3
70
7,000
500 - 5,000
10 - 100
100
0.4 - 3
50
20
5
4
20
—
<10
10
—
100
<30
2
200
—
3
3
8
18
5
10
5
70
20,000
800
100
100
0.4 - 2
50
10
20
20
70
—
<10
10
—
100
<20
16
200
—
10
1 - 10
20
13
2
5 - 10
10
10
100
10
1 - 10
5
0.02
5
10
—
—
—
—
5
0.05 - 10
5-50
300
—
5
5
5
1
1
—
10
aUsing standard methods.
210
-------
TABLE 10-7. SPECIES ENRICHED IN THE LOWER AQUIFER
Conductance
TDS
Ammonia
Bicarbonate
Calcium
Potassium
Sodium
Barium
Boron
Bromine
Fluoride
Phenol ics
Lower
Upper
4.
6
20
8
4
10
13
8
40
10
2
0.3
Enrichment factors
Aquifer Lower Aquifer
Aquifer Springs and seeps
6 5.4
6.6
25
8
4
10
17
16
80
25
.9 50
- 10 0.3 - 10
211
-------
TABLE 10-8. ENRICHMENT FACTORS ESTIMATED FOR SPENT MIS
OIL SHALE LEACHATE
Enrichment factors
Leachate
Gross Parameters
Conductance
pH
TDS
Bicarbonate
Calcium
Carbonate
Chloride
Cyanide
Magnesium
Nitrate
Potassium
Silica
Sodi urn
Strontium
Sulfate
Kjeldahl nitrogen
Sulfide
Minor and Trace Elements
Aluminum
Arsenic
Barium
Beryllium
Upper
2.5
0.6
6
0
0.2
330
6.4
0.01
2.5
0.5
0.37
0.51
1.6
0.20
0.6
Aquifer
- 52
- 2
- 140
.2 - 0.4
- 50
- 1,000
- 310
—
- 67
—
- 70
- 1.0
- 180
—
- 260
—
- 3.3
—
- 20
- 1.0
Leachate
Lower
0.54
0.6
1
0.05
50
3.2
-
0.05
-
0.25
1.0
0.03
-
3
-
1.6
-
0.20
0.08
-
Aquifer
- 11
- 1.5
- 23
—
- 16
- 150
- 160
—
- 235
—
- 7
- 2.0
- 14
—
- 1,500
--
- 3.3
- 20
- 0.13
—
(continued)
212
-------
TABLE 10-8. (continued)
Enrichment factors
Leachate
Minor and Trace Elements
Boron
Bromi ne
Cadmium
Chromi urn
Cobalt
Copper
Fluoride
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Rubidium
Scandium
Selenium
Silver
Thallium
Titanium
Uranium
Vanadium
Zinc
Gross Organic Parameters
TOC
Phenolics
Upper
(continued)
0.4
-
0.3
0.01
-
0.14
0.001
0.12
-
0.6
0.10
1.5
2.5
-
-
0.5
-
-
-
-
1.5
0.1
10
_
Aquifer
- 12
—
- 0.6
- 4
—
- 2.9
- 11
- 6
—
- 5
- 0.8
- 4,000
- 30
—
—
- 200
—
—
—
—
- 50
- 15
- 550
__
Leachate
Lower
0.01 -
—
0.6 -
0.4 -
—
0.14 -
0 -
0.8 -
—
0.6 -
0.15 -
4 -
5 -
—
—
0.5 -
—
—
—
—
0.19 -
0.1 -
3
__
Aquifer
0.3
-
1.2
130
-
2.9
4
3.8
-
5
0.8
1,500
60
-
-
200
-
-
-
-
6.3
15
170
_
213
-------
TABLE 10-9. ENRICHMENT FACTORS FOR RETORT WATERS
Enrichment factors
Leachate
Gross Parameters
Conductance
Alkalinity
pH
TDS
Ammonium
Bicarbonate
Calcium
Carbonate
Chloride
Cyanide
Magnesium
Nitrate
Potassium
Silica
Sodium
Sulfate
Phosphate
Kjeldahl nitrogen
Sulfide
Minor and Trace Elements
Aluminum
Arsenic
Barium
Beryllium
Boron
Bromine
Cadmi urn
Chromium
Cobalt
Upper
10
19
1.0
1.8
3,400
34
0.01
170
0.002
40
0.001
0.17
1.5
0.02
0.001
0.06
0.8
1
0
2.4
0.2
0.26
0.4
0.1
0.07
0.4
Aquifer
- 130
- 130
- 1.6
- 25
- 26,000
- 62
- 1.2
- 10,000
- 80
- 90
- 5
- 120
- 35
- 8
- 22
- 5.4
- 1,000
,700
.17
—
- 600
- 7
—
- 9
- 50
- 1.6
- 60
- 130
Leachate
Lower
2.1
2.4
1.0
0.3
170
4
0.002
25
0.001
40
0.01
0.34
0.15
0.04
«TO
0.3
0.8
-
0.
-
2.4
0.003
-
0.01
0.04
0.20
2.0
0.7
Aquifer
- 27
- 17
- 1.2
- 4
- 1,300
- 8
- 0.31
- 1,600
- 40
- 90
- 20
- 240
- 3.5
- 15
- 1.7
- 30
- 1,000
—
17
.__
- 600
- 0.9
__
- 0.22
- 5
- 3.2
- 12
- 220
(continued)
214
-------
TABLE 10-9. (continued)
Enrichment factors
Leachate
Minor and Trace Elements
Copper
Fluorine
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Radiation, beta
Scandium
Selenium
Silver
Thallium
Titanium
Uranium
Vanadium
Zinc
Lithium
Upper
(continued)
0.04
0.05
0.00001
0.05
0.23
3.3
2
3
9
>0.5
2
>0.33
'2
0.20
Aquifer
- 1.3
- 9
- 15
- 10
- 1.4
- 1,000
- 11
- 50
- 35
—
- >170
—
—
- 21
- >150
- 5,500
- 25
_— _
Leachate
Lower
0.04
0.02
0.001
0.4
0.23
5
2
6
1.8
-
>0.5
-
-
2
>0.50
0.25
0.20
_
Aquifer
- 1.3
- 3
- 100
- 10
- 1.4
- 1,000
- 11
- 100
- 7
—
- >170
—
—
- 21
- 230
- 700
- 25
_—
Organic Parameters
TOC
Unusual Sulfur Species
Total sulfur
TMosulfate
Tetrathionate
Thiocyanate
10,000
6 - 20*
1,200 - 6,400b
400b
65 - 2,000b
3,000
35 - 120d
1,200 - 6,400b
400b
65 - 2,000b
Calculated by assuming that all S in groundwaters (Table 10-3)
is present as sulfate.
^Calculated by assuming background concentrations equal to a
detection limit of 0.5 rag/1.
215
-------
Ca2+ + CO^ CaC03
In fact, Parker et al. (1977) have showip that spent shale does, in fact, re-
move carbonate from surface waters. Nlfy, on the other hand, is likely a
highly mobile species, possibly after conversion to nitrate. In addition,
the more hydrophilic portions of the TOC may also travel with leachate and
prove indicative of groundwater contamination.
As in leachates from spent shale, retort waters appear enriched in those
species forming soluble anions, such as As, Br, Se, and U. The origin of Co,
Hg, and V in the retort waters is less clear, although V is known to form or-
ganic complexes with organic compounds found in crude petroleum oils, and Hg
is known to vaporize from a simulated in-situ retort and to recondense later
(Fox et al., 19785).
In summary, the water quality parameters pH, IDS, Cl, Na, SOd, Mo, Se,
NH4, Br, Se, V, U, and TOC should be considered as potentially valuable indi-
cators of groundwater contamination, both for their elevated enrichment fac-
tors and for chemical reasons.
The utility of enrichment factor estimates is the identification of
chemical species likely to be detected in groundwaters which indicate the
impact of a known source. To evaluate this possible monitoring approach, the
enrichment factors calculated above were categorized (arbitrarily) as follows:
Relative likelihood
Table 10-1 Enrichment of detection
category factor range of impact
1 >500 High
2 50 - 500 Moderate
3 10-50 Low
The results of this categorization are shown in Table 10-10.
For monitoring in the Upper Aquifer for the impact from two major in-situ
sources, consider the following listing:
Water quality constituent
Potential source
of impact Enrichment factor >500 Enrichment factor 50 - 500
Retort water Carbonate Conductivity
Ammonia Alkalinity
Phosphate -Chloride
TOC (or DOC) Bicarbonate
(continued)
216
-------
TABLE 10-10.
RELATIVE LIKELIHOOD OF DETECTION OF MOBILITY FROM VARIOUS SOURCES TO UPPER AND
LOWER AQUIFERS AND SPRINGS BASED ON ESTIMATED ENRICHMENT FACTORS
Lower to
Constituent Upper Aquifer
General water quality
measures
Conductivity —
Total dissolved solids
Alkalinity
Major inorganic ions
Calcium —
Magnesium
Potassium 3
Sodium 3
Chloride
Sulfate
Fluoride —
Bicarbonate
Carbonate
Ammonia 3
Nitrate
Phosphate —
Silica
Organics
Total organic carbon —
Phenol ics 3
Kjeldahl nitrogen
Cyanide
Lower Aquifer In-situ leachate
to springs to Upper Aquifer
2
2
.__
2
2
3 2
3 2
--- 2
2
3 3
...
1
3
— —
...
—
1
3
—
._.
In-situ leachate
to Lower Aquifer
3
3
—
3
2
—
3
2
1
—
—
2
...
—
—
...
2
—
—
—
Retort water to
Upper Aquifer
2
3
2
—
...
3
3
2
—
—
2
1
1
2
1
1
• —
1
2
Retort water to
Lower Aquifer
3
—
3
—
3
—
—
3
3
—
—
1
1
2
1
3
1
....
—
2
(continued)
-------
TABLE 10-10 (continued)
CO
Constituent
Sulfur species
Total sulfur
Thiosulfate
Tetrathionate
Thiocyanate
Trace elements
Arsenic
Barium
Boron
Bromide
Chromi urn
Cobalt
Iron
Lead
Mercury
Molybdenum
Nickel
Selenium
Titanium
Uranium
Vanadium
Zinc
Radiological
Gross beta
Lower to Lower Aquifer In-situ .leachate In-situ leachate Retort water to
Upper Aquifer to springs to Upper Aquifer to Lower Aquifer Upper Aquifer
3
1
2
1
3 31
3
32 3
3 3 — — 3
2 2
2
3
0
«"•"•» j
1
1 13
3 23
2 22
3
2
3 — i
3 3 3
3
Retort water to
Lower Aquifer
2
1
2
1
1
—
—
—
3
2
2
3
1
3
2
2
3
2
1
3
—
Enrichment factor (EF) categories: 1 = high likelihood of detection (EF = >500); 2 = moderate likelihood (EF = 50 to 500)-
relatively low likelihood (EF = 10 to 50).
-------
Water quality constituent
Potential source
of impact Enrichment factor >500 Enrichment factor 50 - 500
Retort water (continued)
Kjeldahl N Nitrate
Thiosulfate Cyanide
Thiocyanate Tetrathionate
Arsenic Chromium
Mercury Cobalt
Vanadium Selenium
Uranium
In-situ spent Carbonate Conductivity
shale leachate TQC (or DQC) TDS
Molybdenum Calcium
Magnesium
Potassium
Sodium
Chloride
Sulfate
Selenium
Examination of this listing indicates that the following constituents may be
unique indicators of impact of retort water or spent shale leachate on the
Upper Aquifer. A unique indicator is one which is in the above listing for
one source, but not for the other:
Possible unique indicators
Retort water In situ spent shale leachate
Alkalinity TDS
Bicarbonate Calcium
Ammonia Magnesium
Phosphate Potassium
Nitrate Sodium
Kjeldahl N Sulfate
Thiosulfate Molybdenum
(continued)
219
-------
Possible unique indicators
In situ spent shale leachate
Retort water
Thiocyanate
Tetrathionate
Cyanide
Arsenic
Chromium
Cobalt
Mercury
Uranium
Vanadium
Following the same procedure for consideration of monitoring in the Lower
Aquifer, the following listing was extracted from Table 10-10.
Potential source
of impact
Retort water
Hater quality constituent
Enrichment factor >500 Enrichment factor 50 - 500
Carbonate Nitrate
Ammonia Cyanide
Phosphate Total sulfur
TOC Tetrathionate
Thiosulfate Cobalt
Thiocyanate Iron
Arsenic Nickel
Mecury Selenium
Vanadium Uranium
Molybdenum Chloride
Carbonate
TOC
Chromium
Nickel
Selenium
Possible unique indicators were then identified from this listing:
In-situ spent
shale leachate
220
-------
Possible unique indicators
Retort water In-situ spent shale leachate
Ammonia Sulfate
Phosphate Magnesium
Nitrate Chloride
Tetrathionate Chromium
Thiosulfate Molybdenum
Thiocyanate
Arsenic
Cobalt
Iron
Mercury
Uranium
Vanadium
Indicator Constituents--
In addition to those water quality parameters for which baseline values
have been established, additional species have been measured on a random basis
in oil shale effluents. These species will be discussed in this subsection.
Inorganic species—Data presented earlier suggest that those trace ele-
ments forming stable, soluble anions under basic, oxidizing conditions are
most likely to be enriched in leachates from a spent in-situ retort. It is
thus interesting to speculate whether additional elements not discussed in
Section 7 or above may behave similarly. Other trace elements which form
anions under basic, oxidizing conditions include Te, Sb, Bi, Po, W, Re, and
I, and their monitoring may, therefore, prove valuable. However, a more com-
plete investigation of the geochemistry of these species is beyond the scope
of this report and their potential mobility remains speculative.
Species such as SCN", $203, and $465 are normally not detectable in
groundwaters and should, therefore, form excellent indicators of groundwater
contamination. Since background concentrations of these species have not
been measured, enrichment factors (Table 10-6) were calculated using esti-
mated detection limits as background concentrations, based on the assumption
that their concentrations were less than the detectable limit. The enrich-
ment factors shown in Table 10-6 for these species recommend them as possible
tracers of groundwater contamination, especially if even lower detection lim-
its can be achieved.
Organic species The enrichment factors for TOC (or DOC) for both leach-
ates and retort waters suggest organic matter as a valuable indicator. How-
ever, the baseline organic content of groundwaters actually varies widely;
221
-------
Leenheer and Huffman (1976), for example, indicate levels of DOC of 30,700
mg/1 for trona water collected near Eden, Wyoming. Few measurements in the
Piceance Basin have been greater than about 10 mg/1. Leachates from raw
shale may contain more organic acids than leachates from spent shale.
For these reasons, individual organic compounds (or compound classes)
which are absent in natural groundwaters, but which are produced by the re-
torting process, should prove to be more sensitive probes of groundwater
movement. For this reason, organic (DOC) fractionation methods, such as
those described by Leenheer and Huffman (1976) may provide a set of useful
indicators for monitoring.
One such type of organic compound could be aromatic acids, which are en-
riched in leachate from spent shale compared to raw shale. In addition, the
smaller (lower molecular weight) aromatic acids should be highly soluble in
the basic conditions expected and should, therefore, follow water movement
closely. The larger acids, although ionized, could be more readily sorbed
and, therefore, migrate less slowly.
Polynuclear aromatic hydrocarbons, which are products of combustion, may
also increase during combustion.
Another likely organic tracer would be in hydrophilic bases. Much in-
terest has focused on such compounds lately because of their biological ac-
tivity and unusually large occurrence in oil shale products. Fruchter et al-
(1977), for example, have found that indoles, substituted pyridines, quino-
lines, and acridines are highly enriched in shale oil as compared to coal-
derived syncrude. Sievers and Denny (1978) have also detected numerous or-
ganic bases, many of which could not be readily identified, in retort waters.
To the extent that such organic bases are retained by groundwaters, they
should provide sensitive and unusual indicators of groundwater contamination.
Stable Isotopes-
It is well established that variations in isotopic abundances—especially
for the light elements—occur naturally through such processes as diffusion,
evaporation, dissolution, and chemical reaction. For example, 13C is about
3 percent more abundant in ocean bicarbonate than in terrestrial petroleum
(Roboz, 1968).
Similar variations in the isotopic ratios of other light elements, such
as H, N, 0 and S, suggest this measurement as a probe for studying the migra-
tion of groundwater. As an example, suppose the 2H/1H ratio is slightly
higher in kerogen than in natural groundwater. Water produced by combusting
kerogen will thus be labeled with a higher 4V1H ratio and could be distin-
guished from natural gr.oundw.ater. Similar considerations to natural and
combustion-produced NH4, 003, and $04.
The variation in stable isotope abundances is normally reported as parts
per thousand variation from a standard:
222
-------
\*2' 1' ~ v1?'1!/
sample standard
6 =
standard
where \2 and Ij refer to the minor and major isotope, respectively.
Variations in isotope ratios are measured almost exclusively by mass
spectrometry. Although any mass spectrometer is capable of measuring isotope
ratios, the measurement of naturally occurring variations requires highly
specialized instruments. Indeed, many isotope ratio mass spectrometers are
dedicated to a single element. Consequently, such instruments are found al-
most exclusively in research laboratories and are numerically absent from
commercial laboratories.
Isotope ratio mass spectrometers are characterized by dual detector sys-
tems which are designed to collect both isotopes simultaneously, thereby min-
imizing errors due to ion current instability. Detector electronics are
specifically designed to yield the isotope ratio directly, and ion sources
typically include a means of switching rapidly between the sample and a stan-
dard of known isotopic composition. The precision with which 6 may be mea-
sured in a routine matter is about 1 mil for H and 0.1 mil for C, 0, and N.
The precision of 6 is typically limited by isotope fractionation which oc-
curs during sample preparation and introduction into the mass spectrometer.
Although studies of isotope ratios in the Green River Formation have not
been found in the literature, other relevant investigations deserve mention.
Friedman et al. (1964), for example, discuss the natural variations of deu-
terium in the hydrologic cycle, including the theory of the fractionation
processes which occur during evaporation, transport, and deposition. They
also report the results of over 1000 determinations of ^H in waters of North
America. Dansgaard (1964) also discusses both the theory and the measurements
of 2H and 1°0 in precipitation.
Holt et al. (1972) and Jensen and Nakai (1961) both discuss natural var-
iations of ™S in environmental samples. Holt et al. (1972) observed pertur-
bations of <534S in surface waters due to rainfall, earth-surface disturbances,
and effluents from sewage treatment plants.
N isotopic ratios have been studied widely, principally as a means of
identifying pollutant sources and characterizing the atmospheric N cycle
(Moore, 1977; Moore, 1974; Hoering and Moore, 1958; Wada et al., 1975). Nat-
urally occurring values of 615N ranging from -15 to +25 have been observed.
Possible problems which may be encountered in the application of the
stable isotope technique to the Green River Formation include lack of back-
ground data, insufficient difference in 6 for natural and contaminated
groundwater, and exchange reactions such as the following:
1H2HO + ^CO" + 1H20 + 2HC03
223
-------
H2180 + HC160~ + H2160 + HC180160;;
Thus, to the extent that carbonates and bicarbonates exchange with, or pre-
cipitate as solid materials, the isotopic composition of certain elements may
be altered.
Sampling and Sample Preservation
Sampling and sample preservation can be a major factor affecting the cost
and effectiveness of a project. In his review of sample preservation and
holding times, Carter (1979) addresses this problem directly and provides ex-
perimentally substantiated holding times for various water quality parameters.
Table 10-11 compares the holding times experimentally established by
Carter for a variety of industrial waste waters with the holding times recom-
mended in the EPA handbook, Methods for Chemical Analysis of Water and Wastes
(U.S. EPA 1974). Table 10-11 also lists the preservatives recommended by
Carter, which are normally, but not always, recommended by the EPA handbook.
The holding times recommended in the EPA handbook have caused consider-
able consternation and may have gained unwarranted credence. It is noteworthy
that the experimentally established holding times shown in Table 10-11, col-
umn 3, are normally considerably longer than those recommended by the EPA
handbook, but that holding times for Hg and pH are actually shorter. Thus,
for industrial effluents, strict adherence to the EPA recommended holding
times would result in dramatically increased cost as well as perhaps compro-
mised data on pH and Hg.
It is thus clear that holding times recommended in the literature may be
neither sufficient nor necessary for the purposes of monitoring groundwater
in the Piceance Creek Basin area. Although Carter's data suggest considerably
longer holding periods, it must be remembered that he dealt principally with
industrial effluents which had elevated contaminant levels. For example,
groundwaters which are exposed in-situ to partial pressures of C02 or h^S
which are elevated over atmospheric partial pressures of these gases may lose
HC03 and HS~rapidly upon standing. It is recommended that, especially for
crucial parameters, holding times be established experimentally for the waters
under study. This could be done, for example, by preparing sealed vials con-
taining known levels of contaminants, the contents of which could be added to
duplicate samples in the field. Recovery in the laboratory of said additions
would then indicate adequate preservation.
The preservation of aqueous effluents from oil shale retorting opera-
tions has been discussed briefly in the literature. For example, Felix et
al. (1977) used high-pressure liquid chromatography to show that the organic
species in retort waters underwent changes when stored at 37°C for 6 weeks,
presumably because of microbial action. The individual -organic species were
not identified. Probably the most well known stability studies have been
performed on the "Omega 9" retort water produced at the Rock Springs Site 9.
Farrier et al. (1977) described this water and found that cooling to 4°C
was the only effective method of inhibiting bacterial growth. Fox et al.
224
-------
TABLE 10-11.
EPA RECOMMENDED HOLDING TIMES COMPARED TO EXPERIMENTALLY
ESTABLISHED HOLDING TIMES (Carter, 1979).
Measurement
Alkalinity
BOD
Bromide
COD
Chloride
Cyanides
Fluoride
Hardness
Iodide
Mercury
Nitrogen
Ammon i a
Kjeldahl
Nitrate +
Nitrite
Nitrite
Oil and grease
Organic carbon
PH
Phenol ics
Phosphorus
Orthophosphate,
dissolved
Hydrolyzale
Total
Total, dissolved
Residual chlorine
Preservative
4°C
4°C
None required
4°C, H2S04 to pH < 2
None required
4°C, NaOH to pH < 12
None required
NH03 to pH < 2
Store in dark
Q.05% K2Cr207, HN03 to pH < 2
4°C, H2S04 to pH < 2
4°C, H2S04 to pH < 2
4°C, H2S04 to pH < 2
4°C
4°C, 800 mg/1 HgCl2
4°C, H2S04 to pH < 2
4°C, H2S04 to pH < 2
4°C
4°C, H2S04 to pH < 2
4°C
4°C, 800 mg/1 HgCl2
4°C
4°C, 800 mg/1 HgCl2
4°C, H2S04 to pH < 2
4°C, H2S04 to pH < 2
4°C
NPDES
Holding
Time
2 wks
48 hrs
4 wks
4 wks
4 wks
2 wks
4 wks
6 mos
4 wks
4 wks
4 wks
4 wks
4 wks
24 hrs
7 days
4 wks
4 wks
1 hrb
4 wks
24 hrs
7 days
24 hrs
7 days
4 wks
4 wks
1 hr
EPA
Recommended3
Holding
Time
24 hrs
6 hrs
24 hrs
7 days
7 days
24 hrs
7 days
7 days
24 hrs
38 days
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
6 hrs
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
(continued)
225
-------
TABLE 10-11. (continued)
Measurement
Residue
Filterable
Nonf liter able
Total
Silica
Specific
conductance
Sulf ate
Sulfide
Turbidity
aFrom EPA Methods
Preservative
4°C
4°C
4°C
4°C
4°C
4°C
4°C, 2 ml zinc acetate
4°C
for Chemical Analysis of Water
NPDES
Holding
Time
2 wks
1 wk
2 wks
4 wks
4 wks
4 wks
1 wk
24 hrs
and Wastes (U.
EPA
Recommended3
Holding
Time
7 days
7 days
7 days
7 days
24 hrs
7 days
24 hrs
7 days
S. EPA 1974).
accuracy of 0.2 pH units, 2 weeks holding time otherwise.
(1978a) also showed that up to 100 percent of the Hg was removed by bacterial
action from retort waters produced at the Laramie simulated in-situ retort
unless the samples were stored promptly at 4°C.
General references describing sampling procedures are available from the
U.S. Geological Survey and U.S. Environmental Protection Agency (see, for
example, Brown et al., 1970; U.S. EPA, 1976; and U.S. EPA, 1977). These
should be readily available and will not be discussed here.
Chemical Analysis and Costs
This discussion is meant to aid the reader in the efficient selection of
analytical techniques suitable for monitoring groundwater movement. Both
survey and element-specific techniques are discussed.
Trace Elements—
The most common techniques which are used for trace element analysis are
instrumental neutron activation analysis (INAA), inductively coupled plasma
emission spectroscopy (ICP), spark source mass spectroscopy (SSMS), and
atomic spectroscopy with its various modifications (AA). Each technique has
strengths and weaknesses which should be recognized.
226
-------
Table 10-12 compares these techniques on the basis of their abilities to
detect trace levels of 44 elements. Although not shown on the table, the
limit for SSMS is typically 1 ug/1 for most elements. The detection limits
for ICP were obtained from a recent review of an ICP spectrometer in use at a
DOE synfuels laboratory, and were determined with artificial, multielement
standards. The detection limits shown for a flamelsss (carbon rod) and flame
AA were taken from the manufacturer's literature. The limits for INAA were
for a routine survey available on a commercial basis. The working limits
shown in the table are the lowest concentrations typically reported by a rou-
tine analytical services laboratory located in Denver. In this case, the
working limits are typically several times the detection limit, since the
method of choice in an analytical services laboratory is determined by regu-
latory requirement, economics, and ease of operation. It should be recognized
that data in Table 10-12 represent a common basis for discussion, but that
detection limits are often degraded in complex samples or improved by special
pretreatment processes.
In addition to the detection limits, the precision and importance of
interferences should be considered. ICP is relatively free of matrix inter-
ferences, but is subject to spectral interferences. For example, the DOE
operators have reported poor accuracy for U, Co, As, and Cd on complex sam-
ples, presumably because of spectral interferences. AA has fewer spectral
interferences, but special corrections may be needed for background or matrix
interferences. The precision of AA or ICP spectrsocopy is typically ±10
percent when used by trained personnel. INAA is often considered a reference
method for trace elements because of its relatively high precision at trace
levels and freedom from matrix interferences. SSMS is typically subject to
fewer interferences than either ICP or AA, but the routine precision for this
technique is about ±40 percent, although precisions of ±3 percent have been
reported in the literature using electrical detection under tightly controlled
conditions. Since samples for SSMS must be dried onto a graphite substrate
and placed in a vacuum, volatile elements such as Hg, S, and Se may be lost,
especially under acidic conditions.
It is obvious that no single method is a panacea. INAA is attractive
because of its detectability for the potential low-level indicators As, Sb,
Se, Te, U, and V. SSMS is favored as a survey technique because it provides
uniformly low detection levels and broad elemental coverage. The other meth-
ods listed in Table 10-12 are attractive as monitoring tools because of their
adequate precision and detectability for many elements.
Organic Methods--
Common techniques which are available for the determination of trace or-
ganic species in complex mixtures include gas chromatography (GC), combined
gas chromatography/mass spectroscopy (GC/MS), high-pressure liquid chroma-
tography (HPLC), and thin-layer chromatography (TLC). Recent advances in
controlling the variables in TLC are also giving rise to high-performance,
thin-layer chromatography (HPTLC).
227
-------
TABLE 10-12. COMPARISON OF ANALYTICAL TECHNIQUES FOR TRACE ELEMENT DETERMINATIONS3
ro
r\3
CO
Detection limits
Element
Ag
Al
As
B
Ba
Be
Bi
Ca
Cd
Co
Cl
Cr
Cu
Ga
Ge
Fe
F
ICP
(vg/i)
3
3
16
15
1
1
80
2
15
5
—
3
4
30
20
5
—
Flameless
AA
(yg/D.
0.03
2
15
2
0.2
1.4
0.06
0.02
0.8
—
0.5
0.4
2
_—
0.5
—
Flame
AA
(yg/D
2
20
100, 2d
2,000
20
0.7
46
2
0.7
7
—
5
2
40
100
6
—
Instrumental
Neutron
Activation
Analysis^
(yg/1)
0.5
100
0.5
NA
100
NA
NA
1,000
0.10
0.5
500
2
300
v/70
NA
200
200
Colorado water
Working limit, quality standards
Denver Laboratory cleanest classification
(yg/D
0.05
100
2
50
50
5
500
50
2
10
200
10
10
—
—
10
100
Method0
B
A
B
C
A
A
A
A
A
A
C
A
A
—
—
A
D
(ug/D
0.1
100
50
750
1,000
10
—
—
0.4
—
—
50
10
—
—
300
_«.»
(continued)
-------
TABLE 10-12 (continued)
ro
no
1C
Detection limits
Element
Hg
K
Li
Mg
Mn
Mo
Na
Nb
Ni
P
Pb
Sb
Se
Si
Sn
Sr
S
ICP
(wg/D
600
50
50
1
5
7
90
30
9
30
20
60
20
30
12
10
___
Flameless
AA
(wg/D
12
0.2
0.4
0.006
0.04
0.6
0.02
—
1
—
0.3
3
6
7
1
0.8
___
Flame
AA
(vg/i)
0.4b
2
2
0.2
2
30
0.3
3,000
8
—
15
40
250, 2d
200
30
2
_ —
Instrumental
Neutron
Activation
Analysis^
(yg/D
0.5
300
NA
5,000
20
3
70
«r25,000
NA
NA
NA
0.5
1
NA
80
2,000
NA
Colorado water
Working limit, quality standards
Denver Laboratory cleanest classification
(pg/D
0.02
100
5
50
5
5
100
—
10
100
1
50
5
1,000
500
10
___
Method^
d
A
A
A
A
B
A
—
A
C
B
A
B
C
A
A
__-
(yg/D
0.05
—
—
125,000
50
—
—
—
50
—
4
___
10
—
—
—
___
(continued)
-------
TABLE 10-12
no
CO
o
Detection limits
Element
Te
Ti
Tn
Tl
U
V
Zn
W
Br
I
ICP
(pg/D
5
1
—
200
500
2
10
—
—
—
Flameless
M
(wg/D
—
—
0.6
1,000
10
0.02
—
—
—
Flame
AA
(yg/1)
40
50
—
13
60,000
50
1
—
—
—
Instrumental
Neutron
Activation
Analysis*1
(wg/D
2
200
0.2
NA
1
1
10
30
1
30
Colorado water
Working limit, quality standards
Denver Laboratory cleanest classification
(pg/D
—
300
—
5
2
5
5
—
—
—
Method0
—
A
B
£
A
A
—
—
—
(vg/i)
—
—
—
15
30
—
50
—
—
aDetection limits correspond to approximately 20 times the background noise level. Working limits
typically correspond to several times the background noise level and are based on a wide variety of
groundwater and surface waters using equipment in a routine fashion.
Note INAA not approved EPA method.
CA - flame atomic absorption; B - carbon rod atomic abosrption; C - col or i metric; D - electrode;
E - fluorometric,
generation.
NA - not available under normal circumstances or very insensitive.
-------
Standardized methods are not normally available for specific organic
compounds since operating parameters are optimized for each substrate and
analyte.
For the more tractable species, literature references may be found for
similar substrates, although as a general rule a significant effort will be
required for implementing, adapting, and "debugging" methods for groundwaters
in the oil shale area. Organic bases are a particular problem since they
readily decompose and since analytical methods are poorly developed.
Instrumentation should include a GC, GC/MS, and HPLC as a minimum, along
with other standard analytical equipment. The GC/MS should be capable of op-
erating with capillary columns and be capable of peak switching and single
ion monitoring. A specific nitrogen detector on the GC should be considered
essential for the determination of organic bases (Sievers and Denny, 1978).
Nonspecific separation schemes are also available for classifying the
types of organic compounds in water (Hamersma et a!., 1976; Leenheer and
Huffman, 1976). Such schemes can provide a first warning of the groundwater
changes and can indicate otherwise unsuspected changes. The procedures by
Leenheer and Huffman may be of special interest since it was originally con-
ceived as an aid in understanding the movement of organic materials in ground-
waters. The procedure operates by separating hydrophilic and hydrophobic aci-
dic, basic, and neutral compounds based on their adsorptive characteristics
on artificial resins. In this scheme, the hydrophilic fractions should be
most mobile in groundwater, while the hydrophobic fractions should most read-
ily be retained by sorptive clays and minerals.
Other Inorganic Species—
For a wide variety of commonly occurring inorganic species, standard
methods have been developed and tested which are reliable when applied to
typical surface waters or groundwaters and which can be performed with a min-
imum of equipment (U.S. EPA, 1974; American Public Health Association, 1976;
U.S. Geological Survey, 1970), Although standard methods must not be applied
blindly to oil shale waste waters (or to other waste waters), it is believed
that many standard methods can be modified slightly in order to produce more
reliable results. In any case, a carefully designed quality assurance pro-
gram is highly recommended.
This subsection first discusses several representative standard analyti-
cal procedures, analytical problems which occur, and possible solutions. A
discussion of possible additional procedures which could be used to better or
more efficiently analyze oil shale waste waters then follows.
Total suspended and dissolved solids—Normally these are determined by
drying an aliquot of water at 103° to 105°C. In retort waters, this may
cause the loss of ammonium carbonate and result in an artificially low result.
A possible.solution is evaporation at a different pressure and temperature to
more selectively remove the water, or complete evaporation of ammonium car-
bonate, which is then determined separately.
231
-------
Alkal inity— Normal ly. alkalinity is measured by titrating with dilute
acid. Results are typically interpreted as total bicarbonate and carbonate.
In retort waters, dissolved ammonia and organic acids are also titrated so
that the results should be interpreted as "total titratable base." Another
method is to determine carbonate and bicarbonate by measuring total inorganic
carbon in a TOC analyzer and adjusting the pH and ionic strength. Other op-
tions include acidification -of the sample and determination of the evolved
C02 titremetrically, colorimetrically, or by hydrogenation and the detection
of methane.
Chloride—Chloride is often determined by the subsequent reactions in a
continuous flow system:
2CT + Hg(SCN)2 * HgCl2 + 2SCN~
SCN- + Fe3+ •» Fe(SCN)x
The colored ferric thiocyanite complex is then detected colorimetrically.
In retort water, thiocyanate is thus detected as chloride. This problem
should be removed by chemically oxidizing the thiocyanate prior to analysis.
Alternatively, analyzing subsequent samples with and without the addition of
Hg{SCN)2 may provide a determination for both chloride and thiocyanate.
£H--pH electrodes are subject to fouling by oils. This common problem
can be overcome by frequent standardization or a cross check with a series of
pH indicators, which are certainly as accurate, if not as convenient.
Nitrate — Often nitrate is determined by the automated Cd reduction
method. A common problem is the fouling of the Cd reduction column by organic
materials. A possible solution is extraction of the organic material prior
to analysis, or the use of an alternate reducing agent, such as hydrazine.
BOD— In our experience, the normal BOD determination is not reproducible
unless acclimated seed is used.
Ammonia — Often ammonia is determined with a selective ion electrode
(which is subject to fouling by organic materials). A likely solution is
removal of the organic materials by extraction, by filtration with a hydro-
phi lie filter, or by the use of macroreticular resins.
Other constituents— It is likely that similar problems and relatively
straightforward solutions may exist for other assays, such as fluoride and
sulfate. Such minor modifications may be simple and, indeed, are often prac-
ticed by the alert analytical chemist. There are, of course, requirements
for entirely new or greatly improved analytical methods. Possible analytical
schemes are discussed below as examples.
Determination of the complex mixture of sulfur and-nitrogeg species found
in_retort waters is an unresolved problem. In addition, S, 8203, SaOg, S3°6>
504, SCN", and CN'can interreact and thereby change their chemical form. SOT
can further react with oxidizing agents, which might be used in water treat-
ment, to form the highly toxic cyanogen chloride.
232
-------
One approach which has been used (Stuber et a!., in press) for this
problem is the cyanolysis of the various sulfur oxides with selective cata-
lysts (Kelly et al., 1969). The resulting SCN" was detected colorimetric-
ally as the ferric thiocyanate complex. However, it has not yet been shown
that the catalysts are sufficiently selective or that they do not occur nat-
urally in sufficient quantities in waste waters.
There are several possible approaches to this problem which would be
considered:
• Ion chromatography
• The development of coloring agents specific for thiosulfate,
thiocyanate, tetrathionate, etc.
• Polarographic techniques which distinguish between the various S
and N species on differing oxidation potentials
• Surrogate tests.
The latter tests assume that sgeciation of the_various forms of S and N is not
essential. As an example, 8305, 8305, and $465 could be determined as a group
using the cyanolysis procedure of Kelly et al. (1969).
An especially attractive technique for such complex waters is ion chroma-
tography. Because it is a separatory technique, complex and selective reac-
tions are not required. Ion chromatography holds the possibility of chroma-
tographically determining cyanide, thiocyanate, sulfate, thiosulfate, tri-
thionate, tetrathionate, sulfide, as well as phosphate, fluoride and nitrate,
minutes after sample collection. Because ion chromatography detects ions non-
selectively, the presence of unexpected peaks alerts the analysts to unknown
ions. Thus, the analyst can often detect previously unexpected compounds.
At the other extreme are tests which would measure, for example, total
sulfur in all forms. Such a technique could be used to alert the analysts to
the need for a more detailed analysis of sulfur species.
Costs--
The following are estimates of current laboratory unit costs for chemical
analyses, based on single sample submission:
Trace metals by AA using standard curves $ 6.00/sample
Trace metals by AA using the method of standard 15.00/sample
additions
SSMS 225.00/sample
INM with multiple exposure and counting periods 225.00/sample
ICP 45.00/sample
(continued)
233
-------
Po-210 by alpha spectroscopy 64.00/sample
Ion chromatrography 50.00/sample
6C scan using developed, but nonstandard methods 300.00/sample
GC/MS 450.00/sample
Most metals measured by AA can be quantified using standard curves rather
than standard additions. Exceptions are As and Se. It is recommended that
most other trace elements be analyzed by standard additions at least once when
dealing with unusual waters.
The prices listed above have been based on previous price quotations and
current price lists, as well as simple estimates by contributors to this
study.
It must be realized that these prices reflect methods which are already
developed. Implementation of new methods must constitute a separate cost
which would precede the actual analyses.
Data Analysis and Presentation
Data Analysis—
Data analysis procedures include (1) checks on data validity, and
(2) methods for presenting data for interpretation for environmental de-
scription or control purposes. Data checking procedures include:
• Cation-anion balance
• TDS-conductivity comparison
• Conductivity-ion comparison (meq/1)
• Diluted-conductance method.
The cation-anion balance check involves considering the theoretical
equivalence of the sum of the cations (expressed in mi Hi equivalents per
liter (meq/1)) and the sum of the anions (in meq/1). Because of variations
in analysis which may be unavoidable, exact equivalence is seldom achieved.
In general, the inequality observed can be expected to increase as the total
ionic concentration increases. When using this method, it is assumed that
analyses of all significant ions have been included and that the nature of
the ionic species is known. In addition, it should be noted that compensat-
ing analytical errors can fortuitously produce a close ion balance. Hence, a
combination of quality control (e.g., replicate analyses, use of standard
references, spiked samples, etc.) and data checking procedures should be
employed.
For other analysis checks, samples can be evaporated to dryness at 180°C
and the weight compared to the total solids determined by calculation. This
check is approximate because losses may occur during drying by volatilization
and other factors may cause interference (Brown, Skougstad, and Fishman,
234
-------
1970). Another recommended check on analyses involves multiplying specific
conductance (umhos/cm) by a factor ranging from 0.55 to 0.75. The product
shoxild approximately equal total dissolved solids, in mg/1, for water samples
with IDS below 2000 to 3000 mg/1. Also, the specific conductance divided by
100 should approximately equal the meq/1 of anions or cations. This rela-
tionship is useful in deciding on which sum, cations or anions, is in error.
A more refined method for checking TDS by the electrical conductivity rela-
tionships, called the diluted-conductance method, may also be employed.
Proper design of the monitoring program with regard to selection of mon-
itoring sites, sampling frequency and analytical methods, and implementation
of quality control measures will alleviate such data interpretation problems.
Good monitoring design can deal effectively with sources of data variability,
such as operational variability of field instrumentations and errors in cal-
culations or analysis.
Other significant sources of data variability are events such as in-plant
spills, poor in-plant housekeeping practices, temporary process or control
equipment failure or modification, and other in-plant events. These events
may be entirely random (e.g., spills) or somewhat cyclic (e.g., equipment
maintenance) in nature. Effectively dealing with these sources of data vari-
ability requires liaison with facility operators. Ideally, this communication
should be of two types, namely to assure that (1) monitoring personnel have
adequate knowledge of facility operations (and deviations), and (2) that plant
developers have access to monitoring data and the evaluations made of that
data. Such intercommunication can enhance data interpretation efforts.
Data Presentation-
Data presentation and interpretation are key aspects of monitoring for
environmental detection and control. Several methods are available for or-
ganization and presentation of water quality data. These include tabulation
and graphical tabulation of appropriate water quality criteria or standards,
providing a format for screening data and identifying important sites or pol-
lutant constituents. Ionic concentrations can be expressed as milligrams per
liter or milliequivalents per liter. Other water quality measures may be
segmented into contributing components, such as total and noncarbonate hard-
ness or phenolphthalein and methyl orange alkalinity.
Graphic representations of analyses of the chemical quality of water are
useful for display purposes, for comparing analyses, and for emphasizing sim-
ilarities and differences. Graphs can also aid in detecting the mixing of
waters of different composition and in identifying chemical processes occur-
ring as water moves through the hydrologic regime of the monitoring area. A
variety of graphic techniques is available; some of the more useful ones are
described in the following paragraphs.
A widely used method of data presentation is the bar graph. On a bar
graph, each sample analysis appears as a vertical bar whose total height is
proportional to the total concentration of anions and cations, expressed in
milliequivalents per liter. One-half of the bar represents cations and the
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other half anions. These segments are divided horizontally to show the con-
centrations of major ions or groups of closely related ions, which are shown
by distinctive patterns. Variations include the addition of individual bar
graphs to express levels of other water quality measures, such as hardness or
un-ionized solutes such as silica.
Water quality data can also be plotted as a set of radiating vectors
(Figure 10-5). Related methods of showing concentrations as linear vectors
result in constructions of polygons. These approaches are useful in display-
ing changes in water quality as changes in, for example,.the shape of these
polygons. Trilinear diagrams are another useful method for representing and
comparing water quality analyses (Figure 10-6).
Here, cations, expressed in percentage of total cations (as milliequiva-
lents per liter), plot as a single point on the left triangle. Anions, simi-
larly expressed as a percentage of total anions, appear as a point in the
right triangle. These points are then projected into the central, diamond-
shaped area parallel to the upper edges of the central area. This single
point is thus uniquely related to the total ionic quality, and at this point
a circle can be drawn with an area proportional to the total dissolved solids
concentration. The trilinear diagram is a convenient way to distinguish sim-
ilarities and differences among various water samples as waters with similar
qualities will tend to plot together as groups. Also, simple mixtures of
Na + K 10
t
12-6
15-1
Na +
Ca
SO4
HCO3
Ca >v.Ma
so< a Hco3
Na + K 17-3
Ca
SO,
Mg
HCO,
Cl
HC03
10 15
MIULIEQUIVALENTSPER LITER
Figure 10-5. Water quality data display using vectors.
236
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a.
HI
cc
111
o.
co
<
oc
ii SCALE OF DIAMETERS
§o
o
o T- in
8
40 60
Cl
ANIOIMS
PERCENT OF TOTAL
MILLIEQUiVALENTS PER LITER
Figure 10-6. Trilinear diagram for displaying water quality data.
waters can be identified as the mixture data will plot at locations interme-
diate bewteen the mixture component waters.
Other graphic methods include time series plots, plots of variation in
water quality constituents with distance or depth, area or cross-section plots
of equal water quality lines, and plane maps. The choice of data presentation
is determined by the goals of the monitoring program and the type of audience
to which the data are to be presented. The goal of data presentation is to
provide a clear portrayal of the data for evaluation of environmental quality.
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Data Interpretation and Reporting—
Water quality data from monitoring should be analyzed and interpreted so
as to define quality trends, identify new pollution problems or regions of
improvement, and assess the effectiveness of pollution control activities.
Assessments include such things as identifying segments of the groundwater
systems not meeting water quality standards and projections of impact on var-
ious water uses. The monitoring program should incorporate pertinent data
from all agencies and organizations involved in the monitoring region.
The final result of a monitoring program organized in an area is infor-
mation on water quality. The final task of the monitoring program is to dis-
seminate the information gained in usable forms to the agencies and organiza-
tions concerned with such information.
Monitoring should be summarized in appropriate forms for convenient study
before wide distribution outside of the monitoring agency. This may involve
preparation of tables showing averages and/or changes in water quality. Sim-
ilarly, graphs prepared to readily display long-term trends may be helpful,
as described previously. Maps showing, for example, locations of major known
sources of pollution, areal distribution of concentrations of key pollutants,
and regions having groundwater with qualities not meeting some water quality
criterion can also be shown to be both useful and effective.
Monitoring information should be distributed regularly to appropriate
public agencies—local, State, and Federal. Major industries in the area
should also receive the material as well as cooperating agencies and organi-
zations that contribute monitoring data.
Finally, the monitoring agency would have the responsibility to alert
action and enforcement agencies of critical problems or situations which are
discovered within the monitoring program. This may involve, for example,
detection of hazardous or toxic pollutants which could affect water users.
Prompt reporting of such instances is essential, as is following up with
specialized monitoring efforts for documenting and controlling emergency
situations.
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SECTION 11
MONITORING DESIGN PROGRAM
INTRODUCTION
This report has summarized the results of the initial phas.e of a research
program to address the groundwater quality impacts of MIS retort development.
The goal of this research program is to develop recommendations for the moni-
toring of these impacts. The recommendations will provide a general evalua-
tion and decision framework for design of monitoring programs for specific
sites. In addition, procedures will be recommended for accomplishing the
various evaluation tasks. The topics to be included under these recommenda-
tions are illustrated in Figure 11-1. Preliminary recommendations are pro-
vided in the "Summary and Design Recommendations" (p. vi and following).
Most of these topics (Figure 11-1) have been considered in some detail
in the preceding sections of this report. Uncertainties and insufficient in-
formation exist to varying degrees in all of these areas. It should also be
noted that data base needs for monitoring design may be very site-specific in
many respects. The monitoring guidelines must be in the form of a design ap-
proach rather than a rigid set of specifications on, for example, number of
monitoring wells, geometric configuration of wells, etc.
Based on the information presented in this report, the major issues rel-
evant to monitoring design have been identified and are summarized in the
following paragraphs. Areas of uncertainty are also identified. It is not
the purpose of these discussions to provide preliminary general monitoring
guidelines nor to specifically define monitoring plans for Tracts C-a and
C-b. Data from Tracts C-a and C-b have been utilized in this study to illus-
trate current MIS development plans and environmental monitoring procedures
being used for MIS development.
The purpose of the following discussions is to identify areas of study
focus for Phase II of this research program. The final segment of this sec-
tion presents a preliminary outline of Phase II studies aimed at addressing
the data deficiencies and uncertainties identified during Phase I. The re-
sults of the Phase II studies will be to supplement the information base
developed to date on this project and to provide a basis for developing a
monitoring guideline document, such as illustrated in Figure 11-1. These
recommendations will be based on assessment of anticipated effectiveness for
obtaining needed monitoring information and on cost considerations.
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• Chapter 1. Overview of Monitoring Design Strategy
• Chapter 2. Characteristics of MIS Retorts
— MIS retort development and operation
-- Potential pollutants
• Chapter 3. Assessment of Hydrogeologic Framework and Water Quality
~ Coring and geophysical testing
~ Aquifer hydraulic characterization
— Water quality characterization
• Chapter 4. Mobility Assessment
-- Mobility and attenuation mechanisms
— Hydrogeologic factors
— Flow net analysis
• Chapter 5. Monitoring Well Placement, Design and Operation
— Hydrogeologic considerations (from Chapter 3)
— Mobility considerations (from Chapter 4)
— Water sample collection, preservation, and handling
— Sampling frequency
• Chapter 6. Analysis
— Selection of constituents
— Analytical methods
— Data analysis and presentation
• Chapter 7. Quality Assurance Programs
Figure 11-1. Preliminary outline—monitoring guideline document.
MONITORING DESIGN STRATEGY
The need for preplanning or design of monitoring programs is central to
assuring the quality of monitoring data and the success of a monitoring stra-
tegy. A stepwise planning sequence (one iteration of which is presented in
this report) which is directed toward design of source-oriented monitoring
schemes is recommended. This direction is preferred over regional (or even
tract-scale) design focus because it offers greater opportunity for early de-
tection and possible control of groundwater quality impacts. With a source-
specific orientation, monitoring programs are designed to indicate whether
specific sources are or are not causing a problem. This is appreciably dif-
ferent than, as is the case with a regional focus in monitoring, an indica-
tion of whether or not the tract operation as a whole has already created a
problem.
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This source-specific approach has major implications with regard to the
development of baseline data programs. The near-field (with regard to indi-
vidual sources) hydrogeology and water quality, for example, should be the
emphasis rather than the tract-wide or regional emphasis of the baseline pro-
grams developed to date. This near-field focus is particularly required in
areas such as the Piceance Basin where the multilayered, fractured-rock aqui-
fer systems create a very heterogeneous flow regime. Basin recommendations
for baseline programs are:
• Emphasis on development of hydrogeology and water quality data
within and in the immediate vicinity of proposed MIS retorts or
retort fields
• Detailed coring, geophysical logging, and other sampling to de-
fine the three-dimensional character of permeable zones within
retort fields
• Multiple completion of wells to isolate zones of widely variable
hydraulic or water quality characteristics (well completion has
been shown to have a very large effect on these data)
• Long-term aquifer tests within proposed retort fields (this will
assist design of dewatering programs as well as groundwater mon-
itoring programs).
In addition, the continual interplay between the engineering design of
the mine and MIS retorts and the baseline study programs should be emphasized.
Changes in facility design can be expected to result in altered data needed
for the design of monitoring programs. The extent to which baseline data can
be extrapolated to deal with changes in facility or operation design is fi-
nite, although clearly a matter of professional judgment.
Characteristics of MIS Retorts
MIS Retort Development and Operation—
The general features of the development and operation of MIS retorts are
described in Section 2. Note that specific descriptions of Tract C-a and C-b
developments are also presented as examples of commercial-scale MIS opera-
tions. It is anticipated that these MIS designs may change during the course
of this research program as a result of new technology development of site-
specific requirements on Tracts C-a and C-b. In addition, some uncertainty
now exists with regard to access from within the mine for monitoring purposes.
Interaction with tract developers will be needed as this research proj-
ect progresses in order to assure an adequate representation of this emerging
industrial technology. Specific areas to be addressed include the following:
• Methods proposed to assist sealing or stabilizing abandoned
retorts
• Flow, treatment, and disposition of retort waters
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• Access to abandoned retorts themselves for sampling
• Access to retort zone for monitoring.
Potential Pollutants--
The general characteristics of potential pollutants from leaching of MIS
spent shale and from MIS retort water are presented in Section 3. Most of
these data utilize simulated in-situ spent shale samples; retort waters from
various simulated in-situ, surface retorting, and true in-situ experiments
(in Wyoming); and extrapolation from characterization of surface-retorted
spent shale. These data offer a fairly good basic picture of what may be ex-
pected from MIS operations such as projected for Tracts C-a and C-b. Few data
are available from MIS testing at Logan Wash by Occidental Oil Shale, Inc.
Basic uncertainties exist with regard to chemical characteristics of MIS
spent shale leachate and retort water and the potential variability of these
characteristics in time and space. These topics are closely related to the
evaluations of leaching, mobility, and attenuation to be discussed later in
this section.
The focus of characterization analysis should be one relevant for defin-
ing monitoring needs. Testing and analyses are needed to better identify
chemical constituents which may be most appropriate for monitoring MIS re-
torts. Such constituents would indicate an impact on groundwater quality by:
• Appreciable change in concentration
• Presence of a constituent not normally associated with
groundwaters
• Change in relative magnitude of various constituents (e.g.,
stable isotopes or organic fractions).
It would be advantageous to identify chemical constituents which would indi-
cate the differential contribution of in-situ spent shale leachate and other
residuals of retorting (e.g., retort water (shale oil)) remaining in the
retort zone. Preliminary evaluations of these matters are presented in Sec-
tion 10. This topic is also related to the selection of constituents, ana-
lytical methods, and data analysis segments of monitoring designs.
Assessment of Hydrogeologic Framework
A great volume of data on geologic characteristics, aquifer hydraulic
parameters, and existing water quality has been developed on the Federal Oil
Shale Lease Tracts. Data for the Colorado tracts presented in environmental
baseline reports are summarized in Sections 5 and 6 of this report. Prelimi-
nary evaluation of these data has revealed the following areas for further
evaluation:
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• Use of coring and drilling information and geophysical testing
associated with exploration activities in the design of hydro-
geologic testing
• Use of selected methods for better defining the location and
properties of fractured or solution-cavity intervals
• Use of the above data sets to identify well construction re-
quirements (e.g., perforated zone) and monitoring design
• Aquifer test methods (including well location, pumping period,
and data analysis)
• Influence of site-specific hydrogeology and well construction on
water quality sampling, and water-level measurements, and aqui-
fer testing data.
The initial three topics listed above are yet to be explored in detail in this
study. The geophysical logging data have characteristically been segmented
from the hydrologic data and were, for the most part, not reported in envi-
ronmental baseline studies. Detailed interpretation of individual fracture
zones as they may relate to groundwater flow, to potential pollutant mobility,
and to influence on water quality samples has not been a large part of well
design and monitoring programs.
In addition, recent testing related to development of dewatering-
reinjection programs on Tract C-a has not been fully evaluated with regard
to the application of these data to monitoring design. This effort will be
undertaken during Phase II of this project.
Aquifer test methods employed on Tracts C-a and C-b are discussed and
evaluated in Section 5. Areas of concern include:
* Location of test wells relative to MIS retort fields
• Selection of interval to be tested
• Duration of pumping
• Data analysis (e.g., relative to anisotropic conditions in the
oil shale region).
Review of Tract C-a and C-b activities has provided some illustration
relevant to these issues. For example, possible inconsistency exists in def-
inition of the location of Upper and Lower Aquifers on Tract C-a. On the one
hand, data show .lack of aquifer interconnection across the Mahogany Zone.
Well perforation sections were also selected using these data.
Several problems were also noted concerning aquifer tests conducted on
the oil shale tracts:
• Test duration too short
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• Nonconstant pumping rate not adequately accounted for in the
test data analysis
• Improper correction of residual drawdown in pump-recover-pump
approach on Tract C-b
• Improper analysis of recovery data
• Need correction for partial penetration
• More accurate water-level measurement methods needed.
Because of the heterogeneity of the hydrogeology of the oil shale region,
aquifer tests should be conducted within proposed MIS retort fields. The dur-
ation of pumping may need to be very lengthy (e.g., more than 30 days) to ade-
quately define boundary conditions (e.g., faults) in the test area. Data
analysis methods appropriate for the anisotropic conditions, possible par-
tially penetrating conditions, etc. must be selected to properly characterize
groundwater flow conditions (see Section 5).
In general, programs for characterization of the hydrogeologic framework
(1) should be focused on specific potential sources of impact (e.g., MIS re-
tort fields) and (2) are probably best developed as a sequence of events of
testing, data analysis, and progressing to further tests as indicated by the
analysis. It would be advantageous to sample and to test the various perme-
able zones individually to better identify flow paths through proposed retort
zones.
The limitations of well testing and sampling in heterogeneous hydrogeo-
logic situations should also be recognized. Mine shaft and sublevel excava-
tion activities offer an excellent opportunity to supplement information
gained in pre-mine testing. Mapping of fractures and sampling water entering
the mine, and collection of data during any in-mine drilling activities,
should be integral parts of groundwater monitoring efforts.
Mobility Assessment
Evaluation of mobility and attenuation of potential pollutants in the
subsurface is probably the most significant of the uncertainties existing in
the development of groundwater quality monitoring programs. Some of this un-
certainty is related to issues of the nature of potential pollutants and of
the complex character of the hydrogeologic framework of the oil shale region.
Discussions in Section 7 and Appendix A indicate that numerous simplistic
models may be conceptualized. The actual predictive capacity of these models
is subject to severe question because of the paucity of data available to
validate the model results. However, from these simplistic analyses, several
general conclusions can be drawn:
• Under certain hydrogeologic conditions (resulting from site-
specific predevelopment conditions and modifications in the
hydrogeologic framework (e.g., from dewatering and rubbling of
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in-situ retorts)), interaction between abandoned retorts and
groundwater systems is likely
• Leaching of significant amounts of soluble materials is likely
from some in-situ operations
• Appreciable decline in groundwater quality can result from
in-situ oil shale development
• The impacts on groundwater quality may take several years to oc-
cur and have a very long duration (several decades or centuries).
The utility of modeling approaches can be enhanced by two methods:
• Enhanced characterization of the hydraulic properties and flow
paths within and near the retort zone {see preceding discussion
of assessing the hydrogeologic framework)
• Better characterization of leaching properties of MIS spent
shale, including:
— Mass of soluble materials leached (mass per unit mass spent
shale)
— Leaching rates (mass per pore volume)
— Attenuation during flow through spent shale or natural geo-
logic functions.
Such models may need to be parameterized in a very site-specific manner
depending on the variability in spent shale characteristics as related to
variations in raw shale or retorting conditions. The development of such de-
scriptions of potential pollutant mobility is central to monitoring design.
Monitoring Well Placement, Design, and Operation
The placement and design of monitoring wells is defined by the design of
the MIS operation, the site-specific hydrogeology, and by the potential mo-
bility of constituents from the MIS retorts. Flow net analysis, including
consideration of the anisotropic nature of the flow regime, is one key tool
for locating monitor wells relative to the MIS retorts. The need for close
proximity to the retorts was discussed earlier.
Hydrogeologic characterization efforts discussed earlier will assist in
identifying aquifer intervals to be monitored. From a strict technical per-
spective, it is probably best to have separate completions in each aquifer
zone producing appreciable amounts of water or exhibiting water quality which
differs from adjacent zones. Obviously, some judpent would be required. It
would be advantageous to drill and complete several monitor wells as part of
one operation. Comparison of logs and other information from each hole should
be undertaken to assure stratigraphic and hydrologic consistency between mon-
itor wells. Development of such wells during baseline studies would greatly
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assist in defining intervals of perforation for any new wells required to
monitor MIS operations.
The most representative groundwater quality samples are probably col-
lected by puming. Other methods (such as bailing or swabbing) may be ade-
quate provided that the well is properly cleaned out (e.g., several well
volumes removed) prior to collection of samples for laboratory analysis.
Mater Quality Analysis
Basic criteria for selection of constituents for monitoring are listed
above under the discussion of characteristics of potential pollutants. In
addition to these factors related to detection of potential pollutant mobil-
ity, other interpretive capability is also important. For example, constit-
uents indicative of potential toxicity or other possible interference with
water use would be good candidates for monitoring.
PHASE II STUDIES
Phase II of this research program will include a series of sampling,
testing, and analysis tasks. The purposes of these tasks is to provide data
to address the technical and economic issues raised in the preceding discus-
sions. The task efforts defined will be coordinated to the extent feasible
with other research efforts of EPA, DOE, US6S, and tract developers. Ini-
tially defined Phase II tasks are as follows:
• Task 1. Sampling Evaluations
~ Well sampling approaches
~ Well construction
— Sample handling and preservation
-- Monitoring operational features
• Task 2. Hydrogeologic Characterization
— Geophysical methods
~ Other testing procedures
— Evaluate mine development phase data
• Task 3. Characterization of In Situ Sources
— Chemical analysis
— Leaching and mobility experiments
— Selection of constituents for monitoring.
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Task 1. Sampling Evaluations
Sample collection and handling play a central role in any monitoring
program. During preliminary evaluations of the oil shale development, the
following key items of concern have been raised. These items will be further
assessed during Phase II with regard to their influence on groundwater qual-
ity data:
• Well sampling approaches (bailing versus pumping)
•Well construction (size, annular, sealing, casing material,
packing, perforation, etc.}
• Sample handling and preservation (cooling).
Approaches for studying these items are provided in the following subtask
descriptions.
Subtask la, Well Sampling Approaches—
During 1979 and 1980, the U.S. Geological Survey may be conducting a
series of aquifer tests in the Piceance Basin. This testing program offers
an excellent opportunity to evaluate alternative sampling procedures. Spe-
cifically, the following should be addressed:
• Compare water quality of samples bailed and samples pumped from
same well
• Compare water quality of samples collected at various times dur-
ing pumping.
The USGS will be collecting water samples at the end of several hours of
pumping. To supplement these data, additional samples should be collected as
fol 1ows:
• By bailing prior to pumping
• After 2 to 5 well volumes have been pumped from the well
• After 1 hour of pumping.
Thus, data would be collected to characterize a bailed sample (from the per-
forated interval); a very short-term pumping period sample (which may also
approximate samples collected after first bailing or swabbing to flush out
the well); a moderate pumping period (1-hour) sample, and a long-term pumping
period sample (USGS sample).
For this program, the following is proposed as a minimum analytical pro-
gram: major inorganic ions, TDS, pH, DOC, fluoride, arsenic, selenium, boron,
and mercury. In order to minimize lab analysis as a source of variability,
all samples should be analyzed by the USGS.
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The sampling program outlined above will test sampling methods for deep
aquifers in the Piceance Basin. In addition, pumped versus bailed samples
from alluvial wells may be evaluated by taking advantage of the pump-sampling
program utilized on Tract C-b. Similar to the deep aquifer testing program,
samples should be collected as follows:
• Bailing prior to pumping
• After 2 to 5 well volumes have been pumped
• After an extended period of pumping.
Maximum use should be made of the data to be collected by Tract C-b personnel.
The same analytical program outlined above should be used for these
alluvial well samples. To minimize sample variability, the samples should be
analyzed at the same laboratory used by Tract C-b operators.
In addition to the samples collected for laboratory analysis, periodic
field measurements of conductivity and pH should be made periodically during
the pumping period.
This sampling program addresses the effectiveness of alternative sampling
methods. Cost data (personnel, equipment, etc.) will also be compiled to pro-
vide an evaluation of cost effectiveness.
Subtask Ib, Well Construction-
Well construction can affect the nature of groundwater quality samples.
Key elements of well construction include well size, annular seal, casing
material, packing, well development, and selection of perforated interval.
Evaluation of this latter element during Phase II will be closely coordinated
with Task 2 assessments of hydrogeologic characterization approaches (de-
scribed later).
Selection of well size is governed by the'proposed use of a well and the
methods selected for sample collection. For example, if only water level
data are desired, then small-diameter (<2-inch) wells may be used. Depend-
ing on whether pumping, bailing, or other approaches are selected for collec-
tion of water quality samples, larger diameter wells will be needed. Assess-
ment of well sizing will be integrated into the cost-effectiveness evaluation
segment of Task la.
With regard to well sealing, packing, and developing, two activities are
recommended for Phase II:
• Compile descriptions of well construction and development proce-
dures which have been used in the Piceance Basin; Representative
well construction methods will be identified
• Evaluate these various methods with regard to their potential
influence on water quality data collected from the wells.
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A literature search will be conducted to support an assessment of the In-
fluence of casing material on the results of water quality sampling. Consid-
eration of costs and materials strength will be included in this evaluation.
To supplement these evaluations, data from Tract C-b wells collected be-
fore and after recompletion will be analyzed. Both water quality and water-
level data sets will be compared to assist identification of the influence of
well construction on the results of groundwater monitoring efforts.
Subtask Ic, Sampling Handling and Preservation--
The relative remoteness of the oil shale region can create some delay in
receipt of samples at commercial analytical laboratories. In order to test
the influence of these potential sample handling problems on the results of
chemistry analysis, the following preliminary testing program is proposed:
• Split sample three ways and preserve each with EPA-recommended
chemical preservatives
t Refrigerate or cool samples as recommended by EPA
• Ship samples (each split) to laboratory for analysis in follow-
ing sequence:
— First split sample as soon as possible after sampling (same
day if possible)
— Second split 5 days after sampling
— Third split 12 days after sampling.
This is intended to simulate circumstances which can arise during field
surveys: the initial split represents a "best" approach to shipment right
after sampling. The second split represents the situation where samples col-
lected during the week are shipped at the end of the week. The third split
represents either a lengthy field survey (or perhaps one interrupted by wea-
ther or equipment problems) and shipment of samples at the end of two work
weeks. The emphasis here will be on constituents with relatively short rec-
ommended holding times such as alkalinity, carbonate, bicarbonate, nitrate,
sulfate, ammonia, and DOC.
An analytical program similar to that outlined under Task la should be
adequate for this initial testing program. Sample collection should be coor-
dinated with Task la sampling activities. A set of five samples, each split
three ways, should be adequate for this analysis, and give an indication of
the influence of shipment delay on the results of chemical analysis. After
this preliminary testing, additional, more extensive testing of specific con-
stituents will be recommended if the need is indicated.
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Subtask Id, Monitoring Operational Considerations--
Under this topic, several items were identified during the preliminary
project evaluations:
• Physical access to spent retorts for monitoring
• Potential utility of in-situ sensors (e.g., salinity sensors)
for monitoring within abandoned retorts.
To address the first item listed here, mine designs will be reviewed and dis-
cussion with tract developers will be pursued to address the following issues:
• Placement of wells within abandoned retorts
• Potential access through retort bulkheads
• Potential access using abandoned product recovery piping
« Potential utility of "long holes" (drilled adjacent to retorts
for dewatering purposes).
The costs and effectiveness of these in-mine approaches will be compared to
costs of drilling new monitor wells from the surface or from within the mine.
The evaluation of the use of salinity sensors for in-situ monitoring will
be addressed during the above-outlined discussions with regard to physical
access to the retort zone. The operation of such sensors in the abandoned
retort environment will be evaluated as part of Subtask 3b.
Task 2. Hydrogeologic Characterization
The hydrogeologic characteristics of the oil shale region are quite var-
iable. The design of a groundwater quality monitoring program for a given
in-situ operation will be governed by the site-specific hydrogeologic fea-
tures. Baseline monitoring and testing programs have focused largely on the
general tract or regional features. The detailed features of the in-situ
retort field areas are being better defined as a result of, for example,
dewatering-reinjection testing and mine development on Tract C-a. The goal
of Task 2 activities will be to (1) evaluate and recommend testing methods
which are appropriate for hydrogeologic testing programs prior to mine de-
velopment, and (2) identify and analyze data being collected or collectable
during mine development which are applicable to defining monitoring program
needs. Several subtasks have been identified for Task 2.
Subtask 2a, Geophysical Methods--
Section 10 of this report contains a summary of geophysical methods
which may be appropriate for defining the hydrogeologic characteristics of
in-situ development sites. During Task 2a, the following evaluations are to
be performed:
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* Reanalyze geophysical data from tract exploration phases (not
included in environmental baseline reports) with regard to the
utility of these approaches for examining porosity with retort
fields
* Develop cost estimates for implementing the geophysical methods
outlined in Section 10
• Rank alternative approaches relative to cost, potential effec-
tiveness (i.e., producing needed information), and availability
of the various geophysical tools in the oil shale region
t Identify methods which may be useful in existing core holes or
wells to fill in data gaps for Tracts C-a and C-b in-situ retort
fields; recommend testing program (perhaps for summer 1980) and
identify costs.
Subtask 2b, Other Testing Procedures—
In addition to geophysical methods, other testing procedures exist which
are useful for characterizing fractured rock/solution cavity aquifer systems
such as are found in the oil shale region. Some of these are identified in
Section 10. The characteristics which need to be defined by pumping, injec-
tion, or other testing procedures are:
• Hydraulic properties of different fractured intervals
• Characteristics of confining beds (leakance)
• Vertical head gradients
• Influence of faults as hydraulic barriers or pathways.
Aquifer testing conducted during the baseline programs has already been exam-
ined and is discussed earlier in this report. To supplement this evaluation,
the following activities are recommended for Task 2b:
• Analyze subsequent testing associated with dewatering-reinjection
program conducted on Tract C-a
• Develop cost estimates for alternative testing approaches for
defining above-listed characteristics
• Rank these approaches relative to costs, potential effectiveness,
and availability of appropriate testing equipment
• Identify methods which may be useful for testing of existing core
holes or wells on Tracts C-a and C-b; recommend testing program
(possibly for summer 1980) and identify costs.
251
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Subtask 2c, Evaluate Mine Development Phase Data—
As mine access shafts and sublevels are developed, a perspective of the
fractured rock system of the retort field can be gained which greatly supple-
ments the data gained by the various well test and sensing procedures consid-
ered in Subtasks 2a and 2b. Such additional data can be gained by mapping of
fractures encountered during mine development, observing relative amounts of
water entering the mine in different zones and sampling the water quality of
water entering the mine in different zones.
During Subtask 2c, such data collected by tract developers will be com-
piled to supplement the other data on the hydrogeology of the retort fields.
Recommendations for additional data collection will be made as data needs are
identified.
Task 3. Characterization of In-Situ Sources
The term "characterization" is used here in a broad sense and includes
consideration of the following:
• Chemical characteristics of potential pollutants
• Leaching characteristics
• Selection of constituents for monitoring (including utility of
tracers, enrichment factors, and stable isotopes)
• Evaluation of mobility/attenuation mechanisms.
To address these areas of importance (and deficiencies identified in prelimi-
nary evaluations) several subtasks have been identified.
Subtask 3a, Chemical Analysis of In-Situ Sources--
The focus here will be on evaluating the characteristics of in-situ spent
shale, retort waters, and mine water. The initial element of this subtask is
to obtain samples of, or data on, in-situ retorting byproducts. At present,
Logan Wash is the most appropriate site for obtaining such samples since the
retorting technology used at Logan Wash is that to be utilized on Tracts C-a
and C-b. Beyond collection of samples of spent shale for leaching and mobil-
ity evaluations (Subtask 3b), the following are to be considered during Sub-
task 3a:
• Variability of spent shale relative to variations in raw shale
from the interval retorted
• Presence of retort water or other product residues on in-situ
spent shale
• Time variability of retort water quality and quantity during
retorting.
252
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Other data sources include other research programs (such as Laramie Energy
Technology Center) and samples from the initial burn on Tract C-a (projected
now for the spring of 1980).
Initial efforts on this subtask will focus on attempting to compile and
evaluate data collected by Occidental Oil Shale, Inc., and LETC from Logan
Wash. From this effort, additional sampling needs will be identified and a
program developed for the initial Tract C-a retort.
Subtask 3b, Leaching and Mobility Experiments--
Experiments to evaluate leaching and mobility of in-situ potential pol-
lutants should address the following issues:
* Mass of various chemical species leached
• Leaching rates
• Attenuation of leached products during flow through spent shale,
raw shale, and other geologic materials.
Such experiments should approximate, to the extent reasonable, the long time
frame and slow flow rates anticipated for leaching in the retort zone.
As indicated by discussions in Section 7, the mechanisms by which in-situ
retorts may be interconnected with aquifers and may be filled and leached are
unclear. Thus, any leaching simulation will be a rough approximation. How-
ever, several experimental design criteria are apparent:
• Contact time between leaching water and spent shale should be
lengthy
• Natural waters should be utilized for the experiments.
A conceptual experimental design is outlined below:
• Pack a relatively large (e.g., 12-inch-diameter x 6-foot-long)
column with spent, shale
« Column should have ports of at least 1-foot increments for the
following:
— Salinity sensors
-- Open tubes for sample collection
(The placement of salinity sensors is related to Task 1 testing
as well as data collection)
253
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• Flow through the column (bottom to top) should be set at rate of
approximately one pore volume per month
• Column should be filled from the bottom.
Data collection will include collection of a sample at each sample port as
the water reaches that level and weekly thereafter. The analysis program is
outlined later under the Subtask 3c description.
Salinity sensors should be monitored at least daily and the results com-
pared to small water samples collected and checked for electrical conductiv-
ity. The pH of these samples should also be measured at the time collected.
The experimental program outlined above should provide an indication of:
• The mass of soluble materials leached from in-situ spent shale
(mass per unit mass spent shale)
• The leaching rate (mass per pore volume)
• The constituents which may be attenuated (e.g., sorbed or pre-
cipitated) during flow through an abandoned retort column.
In addition, the utility of in-situ salinity sensors will be evaluated (Sub-
task Id) and the use of various constituents as tracers or indicator species
will be assessed (Subtask 3c).
In an abandoned retort field (and assuming aquifer interconnection with
the abandoned retorts and subsequent leaching) groundwater flow through in-
situ spent shale may be followed by flow through raw shale and other materials
of the Green River Formation and ultimately through materials of the Uinta
Formation. To evaluate potential attenuation of leached constituents during
flow through these materials, secondary columns containing these materials
may be constructed to receive the effluent from the spent shale leaching col-
umn. Since flow in the Green River and Uinta Formations is through fractures,
these secondary columns should be packed with relatively large pieces of these
geologic materials to simulate the relatively small surface area available
naturally for adsorption of other attenuation processes.
Other experiments such as those dealing with mobility of potential resi-
dues of shale oil or retort water in the spent shale would also be beneficial.
Their feasibility is contingent upon availability of in-situ spent shale and
analytical costs. Beaker or shaker leaching tests should also be considered
as an alternative test procedure. Such laboratory-scale experiments will be
coordinated with the activities of other oil shale research groups.
Subtask 3c, Selection of Constituents for Monitoring—
Selection of constituents for monitoring includes consideration of the
following options:
254
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• Constituents whose qualitative presence indicates groundwater
quality impact (e.g., sulfur species, some organics)
• Constituents expected to change significantly if groundwater
quality impacts occur (e.g., total dissolved solids, pH, certain
trace elements)
• Constituents which may exhibit a relative change if impacts
occur (e.g., stable isotopes).
The potential use of these approaches in selection of indicator chemical spe-
cies is discussed in Section 10. These evaluations have indicated a number
of chemical species which may be useful indicators. The leaching and mobil-
ity experiments (Subtask 3b) should be utilized to further assess the utility
of the constituents identified in Section 10. The evaluation of the poten-
tial mobility of these indicator species should result in a better definition
of constituents useful for detection and monitoring of groundwater quality
impacts.
From the Section 10 evaluation of enrichment factors, the following con-
stituents were identified as potentially unique indicators in the Upper Aqui-
fer from leaching of spent shale:
TDS Sodium
Calcium Sulfate
Magnesium Molybdenum
Potassium
Similarly, the following were identified for the Lower Aquifer:
Sulfate Chromium
Magnesium Molybdenum
Chloride
Other indicators (constituents not normally associated with natural ground-
waters) identified were:
• Trace elements forming anions under basic, oxidizing conditions
(Te, Sb, Bi, Po, W, Re, I)
• Sulfur species (SCN~, S203, S40g)
• Organics (aromatic acids, PAH, hydrophilic bases.
Constituents for this testing should be selected from these lists plus the
constituents of interest identified under the Task la description.
255
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This initial Subtask 3c evaluation will concentrate on the first two
sets of constituents listed above. The assessment of stable isotope tracers
will be extended with an evaluation of the availability and cost of analysis
of the alternative constituents identified in Section 10. Depending on the
results of this assessment, further testing of the feasibility of using stable
isotopes as tracers will be recommended.
256
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261
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APPENDIX A
CONCEPTUAL MODELS OF POTENTIAL POLLUTANT MOBILITY
Three conceptual models are described in the following summaries. These
models provide a preliminary evaluation of the "state of knowledge" of quan-
titative prediction of the groundwater quality impacts of MIS development.
This set of models is not intended to be complete.
CONCEPTUAL MODEL 1
The following scenario is taken from Amy (1978) and is provided here as
an introduction to the potential groundwater impacts of abandoned in-situ re-
torts. This scenario is based on the concept of a two-aquifer hydrogeologic
system with in-situ retorting of the Mahogany Zone between two aquifers (Fig-
ure A-l).
Prior to and during retorting, adjacent aquifers will be continuously
dewatered in order to prevent groundwater from interfering with the retorting
process. Upon completion of retorting, dewatering operations will eventually
cease and groundwater will slowly migrate into abandoned retorts until steady-
state flow conditions are eventually established. A likely pattern of ground-
water flow through a retort is depicted in Figure A-2. The flow pattern de-
scribed in Figure A-2 is highly idealized and assumes that (1) the confining
shale layer is situated between two aquifers as in the Piceance Basin, (2) the
retort completely penetrates the shale layer and thus establishes communica-
tion between adjacent aquifers, and (3) the head difference between the Upper
and Lower Aquifers is sufficient to produce upward flow through the retort
(as will occur in many parts of the Piceance Basin).
One potential scenario for the transport of leached contaminants is pre-
sented by Amy (1978) (Figure A-2). Groundwater from the Lower Aquifer mi-
grates into an abandoned retort after dewatering operations have ceased and,
eventually, steady-state flow conditions are established. Various organic
contaminants may be leached from spent shale as groundwater flows upward
through the retort. Subsequently, contaminated groundwater enters the Upper
Aquifer and, in response to the existing gradient, flows toward a point of
discharge, such as a well or the gaining reach of a stream.
As contaminated groundwater enters the Upper Aquifer, a certain degree
of dilution will occur as it mixes with uncontaminated groundwater from the
Upper Aquifer. As it flows through the Upper Aquifer, contaminated ground-
water may also be improved in quality as a consequence of natural treatment
262
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Figure A-l. Geohydrologic cross section of the Piceance
Basin showing relationship of in-situ retorts
to adjacent aquifers (Amy, 1978).
WELL
GAINING REACH
OF STREAM
y$$A ABANDONED
'"m\N SITU RETORT
SHALE LAYER
CONFINED AQUIFER
Figure A-2.
\\\\\\\\\\\\\\\\\
Schematic describing possible groundwater transport
of leached contaminants.
263
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phenomena, such as adsorption, ion exchange, filtration, and microbial degra-
dation. Furthermore, contaminant levels may decrease due to dispersion and
diffusion within the Upper Aquifer.
This scenario assumes the interconnection of Upper and Lower Aquifer
zones via the abandoned retorts and a head distribution to provide flow from
the Lower to the Upper Aquifer zone. The potential for interconnection is
uncertain. On Tracts C-a and C-b, the head levels in the Upper and Lower
Aquifer zones in general would not result in flow from the Lower to the Upper
zone. In addition, it must be concluded from the preceding descriptions of
the hydrogeology and groundwater quality of Tracts C-a and C-b that this sce-
nario is a very simplistic expression of the complexities of the Piceance
Creek Basin.
The actual direction and rate of groundwater flow after cessation of
dewatering will depend on the response of the various aquifers and aquifer
zones. Response is expected to vary between different aquifers. The early
response cannot be predicted at this time and hence a likely long-term equi-
librium condition (for some sites) is assumed for this analysis. The magni-
tude and character of potential water quality problems from MIS development
will be greatly influenced by local stratigraphy, groundwater quality, local
aquifer characteristics, and the relation of in-situ retorts to aquifers,
wells, faults, springs, and other hydrogeologic features. In addition, the
effects of operation of a number of MIS facilities in the Piceance Creek
Basin have not been considered.
CONCEPTUAL MODEL 2
The following discussions of pollutant mobility are taken (1) from stud-
ies by Lawrence Berkeley Labs (LBL) on the potential effects of in-situ oil
shale development, and (2) from hydrogeologic assessments for the Rio Blanco
nuclear gas stimulation experiments. Both of these efforts included assess-
ments of groundwater characteristics, including groundwater flow velocity.
LBL (1978) examined the transport of leachate from abandoned in-situ re-
torts using a one-dimensional, longitudinal dispersion model of solute trans-
port in porous media. The validity of this model was not assessed by LBL. A
step input function was used representing an instantaneous increase in leach-
ate concentration from the retort to some level where it remains constant as
groundwater flows through the system. This is probably a better approxima-
tion than a pulse input as it may take several years for a retort pore volume
to be discharged to adjacent aquifers (LBL estimates 10 to 15 years).
Any attenuation due to sorption, ion exchange, or other mechanisms was
assumed by LBL to be linear and instantaneous. LBL (1978) indicated that
solubility, ion exchange, and adsorption may be important attenuation
mechanisms.
• Solubility controls
— Quantitative prediction of solubility/precipitation is not
possible because equilibrium constants for participating
264
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reactions in leachate-aquifer complex are not known
— Leachate will encounter ligands, such as oxides, hydroxides,
carbonates, hydroxide-carbonate minerals
— Organic matter (as well as some inorganic constituents)
present may diminish oxygen levels and enhance solubility
of metals, such as iron and manganese
— Levels of calcium and magnesium are likely controlled by
solubility of carbonates and hydroxides
• Adsorption
— Presence of colloidal material will create sites for adsorp-
tion of organic and inorganic constituents
— Adsorption is highly pH dependent and will likely control
transport of zinc and chromium
• Ion exchange
-- This mechanism is probably of diminished importance due to
the low clay content of the aquifer matrix; the exchange
capacity of fractured oil shale, siltstone, sandstone is
expected to be low
-- The exchange capacity of spent in-situ oil shale was not
evaluated.
LBL used the following relationship to estimate equilibrium composition
of leachate within a spent in-situ retort
10M.m+ (C ).V
r.= 1 Y 9 (A-
where C^ is the average concentration of the i^1 constituent; M^ is the mass
(in milligrams) of the ith constituent per 100 grams spent shale (see Sec-
tion 3); m is the mass of spent shale in a single retort (3.4 x 10° kilo-
grams); (Cg)-j is the concentration of the itn constituent in. groundwater in
milligrams per liter; and V is the pore volume of a single retort (9 x 107
liters). This approach resulted in the estimates listed in Table A-l. The
most limiting factor in making these estimates is the term M-,-; however, the
other terms in the above equation are also rough estimates.
The following parameters were used by LBL in their modeling study (from
Weeks et al., 1974):
• Upper Aquifer
— Transmissivity = 134 ft^/day
265
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TABLE A-l. ESTIMATED COMPOSITION OF LEACHATE WITHIN A SPENT IN-SITU RETORT
LOCATED IN THE PICEANCE BASIN (from LBL, 1978)
Retort located in Piceance Basin
Distilled water
leachate
composition
Constituent (mg/100 g)
Al
B
Ca
Cl
co3
Cr
F
Fe
HC03
K
Li
Mg
Na
N03
Pb
Si
so4
Zn
IDS
TOC
0.095
0.075
3.6
5
30
0.002
1.2
0.0004
22
0.76
0.020
0.002
8.8
0.2
0.014
25
50
0.001
80
0.9
- 2.8
- 0.14
- 210
.5
- 215
- 1.8
- 4.2
- 0.042
- 40
- 18
- 0.42
- 8.0
- 235
- 2.6
- 0.017
- 88
- 130
- 0.025
- 2,100
- 38
Quality
of Lower
Aquifer
(mg/1)
0.18
1.3
18
32
100
0.004
15
3.4
1,000
1.4
0.035
32
510
0.33
1.0
4.8
180
1.4
1,400
12
Average concentration
of leachate within
retort if leached
with Lower Aquifer
"water3
(mg/l)
3.8
4.1
1,200
0.08
60
3.4
1,900
30
0.79
840
7.9
1.5
950
1.4
4,400
46
- 110
- 6.6
2.7b
240
- 8,200
- 68
- 170
- 5.0
- 2,500
- 680
- 16
2.1b
- 9,400
- 99
- 1.6
- 3,300
25C
- 2.3
- 80,800
- 1,140
Average concentration
of leachate within
Quality retort if leached
of Upper with Upper Aquifer
Aquifer water3
(mg/1) (mg/1)
0.14
0.67
61
17
26
0.003
3.1
5.4
620
1.1
0.01
58
280
0.55
0.40
12
360
0.79
1,140
10
3.7 -
3.5 -
2.7
220
1,200 -
0.08 -
48 -
5.4 -
1,500 -
30 -
0.77 -
2.1
610 -
8.1 -
0.93 -
960 -
25
0.83 -
4,200 -
44 -
110
6.0
b
8,100
68
160
7.0
2,100
680
16
b
9,200
99
1.0
3,300
c
1.7
80,500
1,400
3Assumes the mass of spent shale in the retort is 3.4 x 108 grams and the vol
by the retort is 9 x 10? liters. Computed using Equation A-l. For example,
in the second column is computed as:
volume of water contained
the lower B value shown
(0.075H3.4 x 108) + (0.67H9 x 107) „ 4>1
9 x 107
''Based on solubility calculations for reactions presented in LBL (1978)
C8ased on data presented by Jackson et al. (1975)
mg/1
266
-------
— Storage coefficient = 0.001
-- Hydraulic gradient = 0.011
— Thickness of saturated zone = 300 ft
— Darcy velocity = 0.005 ft/day
— Effective porosity =0.1
-- Flow velocity = 0.05 ft/day
* Lower Aquifer
— Transmissivity = 268 ft^/day
— Storage coefficient = 0.0001
-- Head = 25 feet above that of Upper Aquifer (static water
level)
— Hydraulic gradient = 0.011
-- Thickness of saturated zone = 600 ft
— Darcy velocity = 0.005 ft/day
— Effective porosity =0.1
-- Flow velocity = 0.05 ft/day
• MIS retort
-- Potential maximum flow from Lower to Upper Aquifer = 1.1 x
gallons per day (assuming vertical permeability of 500 gallons
per day per square foot and head difference of 25 feet)
— Flow into and out of retort will be limited by lower perme-
ability of aquifers (about 3.3 gallons per day per square
foot); hence typical flow expected is about 3000 gallons per
day)
— Darcy velocity = 0.016 ft/day
-- Effective porosity = 0.2
— Flow velocity = 0.08 ft/day.
Using this model, LBL estimated that travel times of leachate discharged
to the Upper Aquifer would be about 300 years per mile (18 feet per year).
The resultant impacts of a 100,000-barrel-per-day operation on surface-water
quality were estimated as follows:
267
-------
Average Maximum IDS Maximum TOC
annual discharge increase increase
Location (103 acre-feet) (mg/1) (mg/1)
Piceance Creek 14.5 2,600 - 64,000 30 - 1,100
at White River
White River near 532 80 -1,900 1 - 30
Watson
Green River near 4,427 10 - 230 0.1 - 4
Green River
Colorado River 12,426 3-80 <0.01 - 1
at Lee's Ferry
Although simplistic analyses such as those described above provide some
insight into the potential for groundwater quality impact, the nature and ef-
fect of the simplifying assumptions must be considered. For example, trans-
missivities of 134 and 268 ft2/day were used in the model for the Upper and
and Lower Aquifers, respectively. It should be noted that values of up to
1000 and 2000 ft^/day, respectively, have been observed and that the aqui-
fer test methods employed may be questioned (see Section 5). Also, most of
the flow is through fracture sets of varying hydraulic character and strata
of relatively high hydraulic conductivity have been observed on both sides of
the Mahogany Zone. Thus, the flow rates into and out of the MIS retorts may
be greater than the averaged levels used in the model and the potential for
dilution in the Upper Aquifer zone may be diminished.
Two published studies related to the Rio Blanco nuclear gas stimulation
experiment in the Piceance Basin are available: the environmental statement
(U.S. Atomic Energy Commission, 1972) and a related follow-up study of possi-
ble groundwater transport (Knutson, 1973). Initial geophysical testing in-
cluded the following:
• Dual induction resistivity
• Si dewall neutron porosity
• Bore hole compensated sonic
• Gamma ray
• C ali per 1 ogs
• Temperature log.
In addition, short-term jetting tests were conducted on Upper and Lower
Aquifers:
268
-------
Discharge Test Water
rate length Drawdown 1 yielding
Aquifer (gpm) (min) (ft) (ft2/day) interval (ft)
Upper 644 125 33 617 220
Lower 114 261 311 27 110
Hydraulic conductivity was thus estimated to be 2.8 and 0.3 ft2/day in the
Upper and Lower Aquifers, respectively (U.S. Atomic Energy Commission, 1972).
Assuming an average gradient of 100 feet per mile and an effective porosity
of 15 percent (approximately one-half the weighted average total porosity de-
rived from the sidewall neutron porosity log), velocities were estimated as
follows:
With
Representative maximum
velocity gradient
Aquifer (ft per year) (ft per year)
Upper 130 285
Lower 12 25
A later assessment (Knutson, 1973) reevaluated estimates of fracture
porosity and permeability yielded the following:
Average
Thickness Average permeability
Aquifer -(ft) porosity (darcy)
Upper 260 0.125 2.0
Lower 185 0.0198 0.05
Using these parameters and a gradient of 100 feet per mile yielded flow velo-
city estimates of 11.7 feet per day (4270 feet per year) in the Upper Aquifer
and 0.256 feet per day in the Lower Aquifer. At this Upper Aquifer flow ve-
locity, estimated travel time from the C-b boundary to Piceance Creek is 1.2
years. However, the actual time to discharge to Piceance Creek is unclear
because of the uncertain location of the nearest aquifer discharge area to
the surface.
CONCEPTUAL MODEL 3
Because of the as yet unknown operational conditions of in-situ oil
shale retorting in Tract C-a, subsequent effects on groundwater quality are
difficult to assess. It is recognized that inorganic, organic, and trace
metal pollutants will be produced by the retorting. These will be released
from the abandoned retorts into inflowing groundwater. As the retorts fill
with water, the pollutants will go into solution and be transported by the
moving groundwater.
269
-------
Pollutants generated by the in-situ process are described in Section 3.
The largest concentrations and the most mobile are the inorganic ions in so-
lution in groundwater. Prime examples include sodium, bicarbonate, nitrate,
and sulfate ions. These ions tend to remain in the solution, although they
may be affected by precipitation (solubility controls) or biological activity.
The chief mechanism for their reduction in concentration is dispersion--
involving dilution with increasing volumes of groundwater as the constituents
are transported downgradient. The effect is analogous to smoke decreasing in
concentration with distance downwind. However, the effects of dispersion
processes in groundwater are not as great or rapid as in the atmospheric
analogy.
To provide a basis for evaluating the mobility of pollutants from an
in-situ retort operation, a generic analysis will be undertaken based in part
on hydrogeologic conditions existing in Tract C-a. A variety of conditions
will be assumed in order to illustrate different pollutant movements. It is
anticipated that these will be representative of most MIS operations in the
Western United States.
Assumed Retort and Hydrogeological Conditions
Let the development plan for an oil shale tract consist of nine retort
fields to be mined sequentially as indicated in Figure A-3. Each field will
involve a square 4000 feet on a side, while the vertical thickness of the re-
torts will average 800 feet. Retorting will require 5 years to complete in
each field, so that mining of the tract will terminate in Field 9 after 45
years.
Retorts will be mined, then rubblized, and finally burned to transform
kerogen to oil. An abandoned retort will consist of a cavity with spent
shale occupying the lower portion. Assuming the retort is in hydraulic con-
tact with one or more aquifers, as it cools it will fill with groundwater.
Examples of retort-aquifer geometries are sketched in Figure A-4. In Figure
A-4a, a single aquifer overlies the abandoned retort, while in Figure A-4b
the retort connects with Upper and Lower Aquifers.
The large void space (relative to surrounding rock mass) in an abandoned
retort functions as a large-diameter well. The permeability within the re-
tort can be regarded as effectively infinite (i.e., expected inflow rates
will be small relative to maximum possible flow rate through retort). Thus,
groundwater moves into, through, and from a retort with little flow resis-
tance. Representative flow paths for groundwater are shown in Figure A-4
after the retort has filled with groundwater and steady-state flow conditions
have been established. Note in Figure A-4a that groundwater enters and leaves
the retort as a result of the ease of flow within the retort cavity. In Fig-
ure A-4b, the piezometric surface of the Lower Aquifer exceeds that of the
Upper Aquifer; therefore groundwater flows vertically upward within the re-
tort. This situation permits inter-aquifer transfer of groundwater.
An important point to note in both situations shown in Figure A-4 is that
groundwater circulates freely within the retort. By so doing, it continuously
270
-------
3 MILES
-SMILES-
RETORT FIELD = 4,000 FT X 4,000 FT
Figure A-3. Hypothetical oil shale tract showing retort fields
and sequence of development for Conceptual Model 3,
(A) CONFINING LAYER
rrtr
y/x/////
AQUIFER
•RETORT
(B)
-////////.
'////////
1 I
\
1
1
J
I
!
\
UPPE
AQUI
•* RE
LOWE
AQUI
«//,
Figure A-4.
Retort-aquifer configurations and groundwater
paths for Conceptual Model 3.
271
-------
conies into contact with the minerals in the fine-grained spent shale, thereby
dissolving pollutants for subsequent transport of groundwater.
Time to Saturate a Retort
For convenience, assume groundwater begins to enter a retort as soon as
combustion ceases. Flow will be essentially radial within the aquifer, and
then vertical within the retort for conditions sketched in Figure A-5. A
square 4000 feet by 4000 feet is equivalent to a circle with a radius of 2250
feet. From the steady-state well flow equation having the form:
h-h,
an estimate of the average of inflow can be made. Let T (aquifer) = 1000 ft2-/
day, h2-hi = 200 ft, and r2/ri = 3250/2250 = 1.44. This assumes (for illus-
tration here) 200-foot drawdown for piezometric surface in the first 1000 feet
radial distance only with an aquifer thickness 200 of feet. Also, the radius
of influence may be much greater (on the order of miles) resulting in a less
steep gradient and slower time to saturate. Then
Q = 2ir(1000) 44 = 3.42 x 106 ft3/day.
The gross volume of a retort is
4000 x 4000 x 800 = 1.28 x 10 10 ft3
but approximately half of this will be filled with spent shale, reducing the
volume available to groundwater to 0.64 x 10^ ft3. Dividing this volume by
the average inflow rate calculated above yields:
0.64 x 1010
c— = 1870 days =5.1 years.
3.42 x 10°
This result indicates that there will be a 5-year period required to fill each
retort with groundwater before pollutants begin to migrate away from the site.
However, channeling within the retort or fractures in retort walls may result
in migration away from the retort zone prior to complete filling of the retort.
From the above calculations, an estimate of the duration of time that a
tract generates groundwater pollution can be made. First, it will be assumed
for this analysis that pollution from a retort lasts only until the initial
volume filling the retort has been displaced by steady-state groundwater flow.
In actuality, the retort leaching process would be a time series of such pore-
volume units. The observed concentrations downstream (in time or space) would
result from the summation of these units. This is certainly a minimum time
calculation, as it treats the initial retort pore volume as a unit. The wa-
ter entering and leaving a retort is assumed for this simplistic analysis to
272
-------
(A) PLAN VIEW
RETORT
EQUIVALENT CIRCLE
(B) VERTICAL SECTION
RISING WATER LEVEL
V
.11 L.U
\
t t t t t t
/
EQUIVALENT RETORT
—
\
X AQUIFER
Figure A-5. Groundwater flow Into an abandoned retort
(Conceptual Model 3).
originate from one-directional groundwater flow having a width twice that of
an equivalent cylinder. Thus, as shown in Figure A-6, groundwater within a
band 9000 feet wide converges on the saturated retort and then diverges. On
the basis of this dimension and Darcy's law, time to replace the volume of
groundwater in the retort can be calculated. Starting from the equation:
Q = TiW
273
-------
EQUIVALENT CIRCULAR
RETORT OF 4,000 FT DIAMETER
GROUNDWATER FLOW LINE
Figure A-6. Groundwater flow lines through a saturated equivalent
circular retort.
let the transmissivity T = 1000 ft2/day, the slope of the groundwater surface
i = 130/5000, and the flow width W = 9000 ft. Then
Q = 1000(130/5000)9000 =0.234 * 106 ft3/day.
The time to displace the groundwater in the retort becomes the volume divided
by Q, or
T = 2>64 * 10 = 27,400 days = 75 years.
0.234 x 10°
Based upon this displacement time, it is possible to indicate the dura-
tion of pollution production from the oil shale tract. If retort operations
start in Field 1 (see Figure A-3) in Year 1, then according to the above
analysis, retorting will cease in Year 5, groundwater pollution beyond the
retort will start in Year 10, and groundwater pollution from the retort will
end in Year 85.
Applying this reasoning sequentially to the nine fields gives the time
frame of pollution listed in Table A-2. The simplifying assumptions used in
this analysis should be noted as qualifying these estimates. It can be seen
that the potential groundwater pollution from an oil shale tract can be a
long-lasting phenomenon.
274
-------
TABLE A-2. ESTIMATED DURATION OF GROUNDWATER POLLUTION
PRODUCED BY AN OIL SHALE TRACT (RETORTING
OPERATIONS START IN YEAR 1), CONCEPTUAL
MODEL 3
Retort
field
1
2
3
4
5
6
7
8
9
Year of first
pollution
production
10
15
20
25
30
35
40
45
50
Year of last
pollution
production
85
90
95
100
105
110
115
120
125
Migration of Pollutants in an Infinite Aquifer
An estimate of the movement of pollutants can be made assuming no atten-
uation of inorganic pollutants (except by dispersion) and flow in an infinite
aquifer. The velocity of flow can be calculated from the Darcy equation in
the form:
a
where K is aquifer permeability, i is the gradient of the groundwater level,
and a is aquifer porosity. Estimated values include: K = T/b = (1000 ft2/
day)/200 ft = 5 ft/day; i = 130/5000; and a = 0.1. Substituting:
v - 11130^50001 - 1.3 ft/day = 475 ft/yr = 0.1 mi/yr.
With this velocity and the durations of pollution given in Table A-2,
the extent of pollution migration is given by the product of velocity times
duration. The above flow analysis represents an idealized approximate analy-
sis because it neglects inter-retort field flows. Treatment of this flow
complexity is beyond the scope of this monitoring program design. However, it
can be anticipated that this flow interference would tend to delay pollution
migration.
It should be noted that this groundwater velocity calculation method
yields correct estimates for a homogeneous aquifer. However, in an aquifer
275
-------
system with preferential zones of high permeability, the calculation would be
in error, perhaps by several times. This factor is extremely difficult to
quantify, particularly over large distances due to the heterogeneity of the
fractured rock, solution cavity aquifer in the oil shale region. The poten-
tial for channels of rapid flow is greatly enhanced by this type of porosity.
Migration of Pollutants to a Stream
The previous analysis of pollution travel is physically somewhat un-
realistic because rarely would groundwater travel extended distances without
discharge to a surface stream, either as base flow or as a series of springs.
With a velocity of 0.1 mi/yr and groundwater discharge to a stream 5 miles
from the tract, the travel time underground would amount to 5.6 years. Add-
ing 10 years from the start of production means that surface water pollution
would begin about Year 15.6 and continue for some 75 years (see preceding
analysis).
Pollutant Concentration
Because pollution may originate from retort fields at different times,
the total pollution mass varies as a function of time. The time distribution
of pollution can be derived from the data in Table A-2 assuming that the con-
centration emanating from a given retort field remains constant with time.
Actually, this assumption appears reasonable in that mixing within the retort
may tend to produce a uniform concentration which is then replaced with a
subsequent volume of water without pollution. Thus, each retort field may be
illustrated as producing a step-funtion of pollution for a 75-year period
(see preceding analysis). Combining these in the sequence given by Table A-2
yields the pollution concentation curves shown in Figure A-7. Note that a
pyramid-shaped curve is formed with a maximum concentration persisting for 35
years.
Another, and perhaps more realistic, model of these processes is to vis-
ualize considerable mixing as polluted water within the retort is displaced
from below. Density currents may develop as the highly polluted water is
displaced upward by less dense unpolluted water. In addition, rather than
water being displaced uniformly across the entire bottom of the retort, water
may enter the upgradient side of the retort and then channel directly upward
because of its lower density. These effects, plus diffusion, would act to
decrease the concentration of pollutants flowing from the retort but would
also prolong the length of time of leaching from the retort.
Attenuation of Pollutants
The primary mechanism for attenuation of inorganic pollutants underground
is dispersion. By mixing with ever-increasing volumes of groundwater> a plume
of potential pollutants downgradient from an oil shale tract expands in volume
and consequently decreases in concentration. For a given water quality cri-
terion, there is a maximum recommended limit; an example would be $04 = 250
mg/1 for potable water supplies. If the initial $04 concentration of ground-
water leaving the retort exceeds this value, then at some distance from the
retort the quality improves to meet this criterion.
276
-------
o
cc
LU
O
O
O
z
o
O
.o-
20
40 60 80 100
YEARS AFTER START OF OPERATIONS
120
140
Figure A-7. Groundwater pollution concentration as a function of time from
oil shale tract, using Conceptual Model 3.
Determination of the distance from a tract to where the water is of sat-
isfactory quality depends upon three factors:
1. Initial constituent concentration leaving the tract
2. Water quality criterion for a specified water use
3. Physical properties of the aquifei—grain size, grain-size
distribution, porosity, specific surface, gradient, flow
velocity, flow patterns, etc.
The influence of these factors on the resulting concentration of individ-
ual chemical constituents is expected to be quite variable. Concentrations
will also be affected by physico-chemical processses, such as precipitation
and perhaps biological activity. Because of data limitations, it is not pos-
sible to describe quantitatively or precisely the rate of decrease of pollu-
tion concentration by dispersion for aquifers associated with oil shale tracts
in the Western United States. This can only be accomplished based upon field
measurements over a period of several years. Also, the dispersion rate for
each aquifer is undoubtedly different. Models can, however, be useful to
consider general cases and provide some insight into the potential effects on
groundwater quality.
The only scenario that can be stated with certainty is that for a homo-
geneous and isotropic aquifer, dispersion produces an exponential decrease in
277
-------
concentration with distance. This is for a unit impulse input and ignoring
mass transport (Lagrangian view of dispersion). This can be expressed as:
C/CQ
= p-aL
where C/CQ is the relative pollution concentration, a is the dispersion coef-
ficient dependent upon aquifer properties, and L is the distance downgradient
from the tract. For L = 0 , c = CQ; while for L > 0, c < CQ, being some
fraction of the initial concentration eg. Examples of the decrease in pol-
lution concentration with distance are shown graphically in Figure A-8 for
various values of a. Thus, if a = 0.8, then at a distance of 3 miles, C/CQ =
0.50, which indicates the pollution concentration is one-half of its initial
value. Note in: Figure A-8 that pollution concentrations reach zero only at
infinity; invother words, dispersion dilutes but does not remove pollution.
Dispersion is produced by laminar fluid flow through porous media. There-
fore, the above analysis applies only to pollution while it is underground.
Once groundwater discharges into a surface stream, pollution is mixed with the
water by the turbulent motion of the stream. Effectively, this occurs within
minutes so that the concentration of pollution varies with the streamflow di-
lution. Streams near Tract C-a are small, hence pollution concentrations
would be relatively large. But as the water flows to the White River, then
to the Green River, and finally to the Colorado River, streamflow quantities
EC
Z-
LU
u
o
o
o
P
2
LU
'LU
cc
3456
DISTANCE FROM TRACT (miles)
Figure A-8. Relative pollution concentration as a function of distance
from an oil shale tract and of rate of dispersion (a is the
dispersion coefficient).
278
-------
increase, causing pollution concentrations to decrease. Similarly, because
local streams have flows which vary seasonally, it can be expected that pol-
lution concentrations will be least during the spring snowmelt season and
largest during the low-flow season in late fall and winter.
REFERENCES
Amy, G.L., "Contamination of Groundwater by Organic Pollutants Leached from
In Situ Spent Shale," Ph.D. dissertation, University of California,
Berkeley, California, 1978.
Jackson, L.P., R.E. Poulson, T.O, Spedding, I.E. Phillips, and H.B. Jensen,
"Characteristics and Possible Roles of Various Waters Significant to In
Situ Oil Shale Processing," Quarterly of Colorado School of Mines, Vol.
70, 1975.
Knutson, C.F., Project Rio Blanco: Evaluation of Possible Radioactivity
Transport in Groundwater, CER Geonuclear Corporation, Las Vegas, Nevada,
1973.
Lawrence Berkeley Labs (LBL), "Diffuse Source Effects on In Situ Oil Shale
Development on Water Quality", draft report, 1978.
U.S. Atomic Energy Commission, Environmental Statement: Rio Blanco Gas Stimu-
ulation Project, Rio Blanco County, Colorado, April 1972.
Weeks, J.B., G.H. Leavesley, F.A. Welder, and 6.J. Saulnier, Jr., Simulated
Effects of Oil Shale Development on the Hydrology of Piceance Basin,
Colorado, U.S. Geological Survey Professional Paper 908, 1974.
279
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-80-132
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
MONITORING GROUNDWATER QUALITY:
Oil Shale Retorting
5. REPORT DATE
The Impact of In-Situ
APRIL 1980
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Guenton C. Slawson, Jr. (Editor)
8. PERFORMING ORGANIZATION REPORT NO.
GE78TMP-103
9. PERFORMING ORGANIZATION NAME AND ADDRESS
General Electric Company--TEMPO
Center "for Advanced Studies
816 State Street
Santa Barbara, California 931Q2
10. PROGRAM ELEMENT NO.
1NE833
11. CONTRACT/GRANT NO.
68-03-2449
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency—Las Vegas, NV
Office of Research and Development
Environmental Monitoring Systems Laboratory
Las Vegas, Nevada 89114
13. TYPE OF REPORT AND PERIOD COVERED
Project Report •
14. SPONSORING AGENCY CODE
EPA/600/07
15. SUPPLEMENTARY NOTES
. Commercial telephone
16. ABSTRACT
This report presents the initial phase of a research program which will develop a
planning methodology for the design and implementation of cost-effective groundwater
quality monitoring programs for modified in-situ (MIS) oil shale retorting. This
initial phase includes (1) a review of MIS development with regard to potential im-
pacts and a review of current MIS monitoring programs, and (2) identification of key
issues, uncertainties, and unknowns with regard to design and implementation of moni-
toring programs.
In addition, this report presents a preliminary study program for Phase II of the
research effort. Phase II will develop support data to finalize recommendations for
monitoring the impact of MIS retorts.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
Groundwater Movement
Groundwater
In-Situ Oil Shale Retorting
Oil Shale
Mine Wastes
Waste Disposal
Mining Pollution
roundwater Quality
teter Pollution Sources
Monitoring Methodology
ollutant Identification
Pollutant Source
Dil Shale
Western Colorado
08D
08H
081
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
21. NO. OF PAGES
318
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