3EFK
United States
Environmental Protection
Agency
I
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S7-81-131 Oct. 1981
Project Summary
Field Studies on Paraho
Retorted Oil Shale Lysimeters:
Leachate, Vegetation, Moisture,
Salinity, and Runoff,
1977-1980
M. K. Kilkelly, H. P. Harbert, III, and W. A. Berg
A disposal scheme for Paraho
retorted shale utilizing lysimeters to
simulate a low-elevation (dry site) and
a high-elevation (moist site) was
constructed. The study site was
located in western Colorado at the
Department of Energy oil shale re-
search facility at Anvil Points. The
lysimeters were constructed in 1976
and filled with retorted shale in 1977.
Objectives of the study were to
investigate 1) vegetative stabilization
of Paraho retorted shale, as affected
by leaching and soil cover treatments;
and 2) moisture and soluble salt
movement through the soil/shale
profile.
After intensive management and
four growing seasons, only a sparse
(2% to 3%) cover of perennial vegeta-
tion resulted on the Paraho retorted
shale. In contrast, good to excellent
cover was established and maintained
on the soil control and soil-covered
retorted shale treatments.
Initial leaching and irrigation for
plant establishment produced perco-
late from drains below the compacted
shale zone. The percolate from the
Paraho retorted shale treatment mea-
sured a maximum electrical conduc-
tivity (EC) of 35 mmhos/cm and pH of
11.4. The soil control produced
percolate with a maximum EC of 8.5
mmhos/cm and a pH of 8.3. Each
spring the high-elevation lysimeter
received supplemental irrigation to
simulate a zone of higher precipitation.
Percolate produced from these irriga-
tions exhibited a general overall
reduction in both EC (33 to 11.4
mmhos/cm) and pH (11.4 to 8.6) by
1980 on the Paraho retorted shale
treatment. The low-elevation lysim-
eters did not receive additional spring
irrigations and no percolate was
produced from the unleached treat-
ments. When the constructed lysim-
eters were filled with freshly retorted
shale a high temperature (60°C) was
maintained at a 1 -m depth for 30 days.
Prolonged, elevated temperatures of
retorted shale disposal piles could
significantly affect both the amount
and composition of vegetative cover.
This report deals most specifically
with the collection, measurement.
and interpretation of data from 1978
through 1980. A more detailed de-
scription of all measurements and
analyses for 1976-1977 was reported
in Harbert eta). (1979).
This Project Summary was devel-
oped by EPA's Industrial Environmen-
tal Research Laboratory, Cincinnati,
OH, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
-------
Introduction
In recent years, the need to develop
new energy resources within the United
States has become increasingly impor-
tant. In 1973, the U.S. Department of
Interior estimated that the western oil
shale reserves, consisting of over
64,750 square kilometers in Colorado,
Wyoming, and Utah, contained over 9.5
x 1013 I (600 billion barrels) of recover-
able crude oil. These previously un-
developed areas, used largely as range
and wildlife habitats, will be subject to
vast land disturbances with the devel-
opment of an oil shale industry.
Various waste products will be
generated by shale processing methods
making it necessary to develop control
technology in order to limit the environ-
mental impact. One of the major envi-
ronmental problems associated with oil
shale development is the disposal of the
massive amounts of waste material
produced. The U.S. Department of
Interior (1973) estimated that a mature
oil shale industry of 1.6 x1081 of oil/day
(one million barrels oil/day) would
generate approximately 20,000 ha-
m/year of waste material with surface
retorting methods. Part of this waste
might be returned to mined areas, but a
large proportion would require surface
disposal. Not only the large volume, but
also the chemical and physical charac-
teristics of the waste will create
challenges for the development of
control technology.
Thus, the following study was initiated
to evaluate a variety of intensive man-
agement techniques and practices for
the disposal of processed oil shale. A
model was designed to simulate the
disposal of Paraho retorted shale
(direct-heated) at both a low-elevation
(dry site) and a high-elevation (moist
site). Lysimeters were constructed to
measure both the quality and quantity of
percolate which might result from a
processed shale disposal pile. Various
treatments such as leaching and soil
cover were used to investigate the
establishment of vegetative cover on
the Paraho retorted shale.
Methods and Materials
In 1976, a series of concrete lysim-
eters were constructed to aid in model-
ing a disposal scheme for Paraho
retorted (direct-heated) oil shale. The
lysimeters were designed to simulate a
canyon fill disposal site having the
following features:
1. The back face of the canyon fill
gently sloped (2% to 5%) upstream.
2. The front face of the dam steeply
sloped (25% to 50%) downstream.
3. The body of the disposal pile highly
compacted.
4. The exposed surface of either
uncompacted retorted shale or
soil-covered retorted shale of a
sufficient depth to provide ade-
quate plant rooting and moisture
storage.
A study site was selected at the U.S.
Department of Energy, Anvil Points
Research Facility in western Colorado.
The study site, on public land managed
by the Bureau of Land Management,
was characteristic of a semi-arid, low-
elevation disposal site, with an elevation
of 1737 m, and an average annual
precipitation of 28 cm.
Two identical sets of lysimeters were
constructed at this site. One set was
used to simulate the natural low-
elevation site, while the other was to
simulate a high-elevation disposal site.
Because of proximity to water, electricity,
retorted shale, and construction sup-
plies, both sets of lysimeters were built
at the low-elevation site. Sprinkler
irrigations simulated the increased
precipitation associated with a high-
elevation site.
The following replicated treatments
were tested with each lysimeter set on
both a 2%, north-aspect slope, and 25%,
south-aspect slope:
1. Paraho retorted shale, leached.
2. 20 cm soil cover over Paraho
shale, leached.
3. 40 cm soil cover over Paraho
shale, unleached.
4. 60 cm soil cover over Paraho
shale, unleached.
5. 80 cm soil cover over Paraho
shale, unleached.
6. Soil control, unleached.
Each of the treatments, except the soil
control, contained 90 cm of compacted
Paraho retorted shale, covered with
uncompacted shale, and various
amounts of soil cover (for some treat-
ments) to equal a total profile depth of
240 cm. Drains were built into the
lysimeters at both the interface of the
compacted and uncompacted zones and
beneath the compacted zones.
During the filling operation, tempera-
ture measurements of the retorted
shale were made with a thermocouple
probe. A series of thermocouples were
later used to measure surface tempera-
tures throughout the 1977 and 1978
growing season.
The lysimeters were instrumented
with tensiometers, piezometers, neutron
probe access tubes, and salinity sensors
to monitor the water and salt movement
through the uncompacted zones.
Tensiometers were installed at 15, 30,
60, 90, 120, and 150 cm depths to
measure soil and shale matric potential
for 1977. The tensiometer data were
used by other researchers for a hydro-
logical modeling study, and are not
included in this report (Chandler, 1979).
Piezometers were installed to a depth of
150 cm (the interface of the compacted
and uncompacted zone) and read during
the 1977 season. Neutron probe access
tubes were also set to a depth of 150 cm.
Monthly readings of soil moisture by
volume were taken during each growing
season. Salinity sensors were placed at
depths of 15, 30, 60, 90, 120, and 150
cm. Because of erratic readings, the use
of the sensors was discontinued in
1978.
The subsurface drain system within
each treatment area was fitted with a
plastic container for collecting leachate,
an electric sump pump, and a totalizing
flow meter to measure both the rate and
volume of leachate from the lower
drain. Any percolate from the upper
drain, in the interface area, was
collected in a plastic can.
A surface runoff collection system for
each treatment plot consisted of a metal
gutter, pipe, and a culvert with a plastic !
container. The system was completed in
1977 and used to collect snowmelt
runoff and summer storm runoff of later
seasons.
Details on the leaching, fertilization,
and seeding of the treatments, are
provided in the main report. Vegetative
analysis for 1977 was done by the
quadrat method to determine vegetative
cover. For vegetative measurements
1978-1980 the line-transect method
was used. Vegetative cover as well as
species composition was determined.
In September of 1977, core samples
were taken from various treatments in
20-cm increments to a depth of 160 cm.
These samples were analyzed by the
CSU Soil Testing Laboratory for common
cations and anions, pH, and EC. Core
samples were again taken in the fall of
1979 for EC analysis.
Ambient air temperature, precipita-
tion, and pan evaporation have been
monitored since establishment of the
lysimeters.
Results and Discussion
The SAR (Sodium Adsorption Ratio) is
a measure of the ratio of sodium to
calcium and magnesium of soils or
-------
waters and estimates the dispersion
potential posed by exchangeable sodium,
when soluble salts are leached. A
potential sodium dispersion problem
may exist when SAR values exceed 15.
The SAR value of the Paraho retorted
shale suggested such a problem. Other
analyses indicated that the retorted
shale would require fertility amend-
ments for successful vegetative growth.
While plant-available phosphorus was
low for the retorted shale (as well as the
soil), potassium seemed adequate, but
nitrate-nitrogen was low.
Wet-Dry Cycles
After filling of the lysimeters was
completed, a series of wetting and
drying cycles were used to reduce the
pH of the retorted shale. Although the
pH was successfully reduced from 11.4
to 9.2, the EC increased from 4 to 6.1.
The increase in EC was probably due to
the greater solubility of Ca and Mg salts
at a lower pH. Apparently, the amount of
carbonate decomposition was minimal
with the Paraho direct retorting process,
and this allowed rapid recarbonation of
the retorted shale. The pH of the
retorted shale would likely have de-
creased with the natural weathering
process.
Retorted Shale Temperature
Temperatures of the retorted shale in
the uncompacted zone were monitored
with a thermocouple probe following
the filling of the lysimeters in 1977.
Although a sharp drop in the tempera-
ture of the shale (230 to 64-80°C)
occurred within 10 days after place-
ment, an additional 30 days was
required for the shale to drop below
60°C at the 1-m recording depth. This
suggested that a droughty site could
develop if freshly retorted shale was
covered with soil before cooling. A xeric
site would significantly affect both the
amount and composition of vegetation
cover.
Vegetation
The quadrat method was used for the
first year of growth in 1977 to estimate
germination and establishment. The
line-intercept method was used in later
years to provide more quantitative
measurements. The Paraho retorted
shale treatments supported only a very
minimal (2% to 3%) perennial vegetative
cover (Table 1). Observations of the few
perennial species on the Paraho shale
indicated severe stunting and physio-
logical stress. Caution must be advised
when comparisons of total vegetative
cover between the Paraho retorted
shale and other treatments are made.
Values as high as 48% vegetative cover
on the Paraho retorted shale, 2%-slope,
north-aspect of the high-elevation
lysimeters must be carefully scrutinized.
This vegetative cover was almost
completely composed of annual species
such as kochia. This annual was at its
vegetative peak when measured and
with its extremely short-lived habit, left
the treatment almost totally bare and
exposed by mid to late summer.
After four growing seasons the
inability of shrubs (where seeded, on
the low-elevation lysimeters) to either
increase in number or size was observed
on the soil-covered Paraho retorted
shale treatments.
Trace Elements in Vegetation
In 1977 and 1978, plant samples
were collected from the lysimeter plots
for trace element analyses. Large
stands of alfalfa were present as a result
of seed introduced with the hay mulch,
so this species was sampled. Overall,
molybdenum levels of plants from
Paraho retorted shales were judged to
be high (11.5 to 23.5 ppm Mo) (Kilkelly
and Lindsay, 1979). This, combined
with low to moderate copper levels,
could limit the use of this vegetation for
animal forage.
Moisture
In a semi-arid region where seasonal
precipitation seldom exceeds evapo-
transpiration, percolation and water
movement within a pile of retorted shale
should be limited, provided a satisfactory
vegetative cover exists. In this study,
seasonal precipitation over a four-year
period provided a spring recharge of
approximately 20% moisture by volume
(to depths of 60 to 120 cm). Those
treatments with a good vegetative cover
were reduced to approximately 10%
moisture by volume by fall. The moisture
extracted during the growing season by
vegetation resulted in a renewal of
reservoir capacity to contain yearly
precipitation, especially spring snow-
melt. Without satisfactory vegetative
cover, moisture within the profile could
be moved downward with each yearly
recharge and pollution of ground water
could result.
Each year, since establishment,
irrigation of the high-elevation lysim-
eters produced percolate from the lower
drain of most treatments. The purpose
of the extra irrigation was to simulate a
region of higher elevation where
seasonal precipitation exceeded the
evapotranspiration of the native plant
community. The collection and analysis
of percolate from these treatments
could then be used for predicting the
potential for environmental pollution.
The Paraho retorted shale, despite
leaching, continued to support far less
vegetative cover than other treatments,
thereby reducing the extraction of
surplus moisture in the profile. Moisture
recharge and depletion patterns between
other treatments were similar, with the
greatest amount of moisture used by the
dense vegetative cover on the soil
control.
Runoff
The first year that runoff samples
were collected from the newly estab-
lished lysimeters was 1978. The runoff
was of low salinity hazard.
Runoffs from south slopes of both
high- and low-elevation lysimeters
were measured and samples were
collected on March 8, 1979. Recorded
runoff for south slopes was greater than
for north slopes due to the fact that
snowmelt was slower on the north side
and the slope more gradual. Samples of
runoff collected on March 22 were sent
to the CSU Soil Testing Laboratory for
water quality analyses (Table 2). The
salinity hazard for all samples was low
to medium, while the sodium hazard
was low.
Spring snowmelt in 1980 resulted in
runoff only from north slopes. Field
observations indicated that the ground
on the north slopes was frozen with a
thin covering of ice. The south slope
ground was thawed, allowing moisture
to enter the soil or shale, resulting in
little runoff. The low sodium and salinity
hazard combined with the negligible
sediment yield suggested that the
runoff never actually came in contact
with the soil or shale surface, but
merely ran over the layer of ice. No
runoff from summer storms resulted.
Percolate
In 1977, after some treatments were
leached, both high- and low-elevation
lysimeter studies were irrigated to aid
the establishment of vegetation. Only
the high-elevation lysimeter study
received additional irrigation in the
early spring of 1978 and 1979. These
differences were designed to study both
the quantity and quality of the percolate
resulting. In 1980, percolate from the
high-elevation lysimeters resulted from
-------
Table 1 . Vegetative Cover by Species Composition for
Control, 1978-1980
Treatment
Paraho Retorted Shale
20 cm Soil Cover/Paraho
40 cm Soil Cover/Paraho
60 cm Soil Cover/Paraho
80 cm Soil Cover/Paraho
Soil Control
Treatment
Paraho Retorted Shale
20 cm Soil Cover/Paraho
40 cm Soil Cover/Paraho
60 cm Soil Cover/Paraho
80 cm Soil Cover/Paraho
Soil Control
Species Categories
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Species Categories
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial Grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
Perennial grasses
Shrubs
Other
1978
19
2
29
59
2
57
5
47
7
40
16
86
14
1978
8
1
6
42
2
23
45
18
39
3
29
59
3
8
45
4
33
Paraho Retorted Shale, Soil-Covered Paraho Retorted Shale, and Soi
High-Elevation Lysimeter
2% Slope
North Aspect
1979
5
46
72
11
63
39
60
29
59
27
93
2
2% Slope
North Aspect
1979
1
24
18
2
80
28
69
22
3
62
48
2
24
51
6
29
1980
3
48
31
15
32
13
43
24
29
22
33
Low-Elevation
1980
o/
2
24
7
1
61
12
59
13
2
51
25
4
33
20
3
30
1978
14
26
60
8
49
4
44
5
39
10
73
19
Lysimeter
1978
2
5
15
26
3
39
41
2
19
47
12
45
2
11
61
15
8
25% Slope
South Aspect
1979
6
48
71
21
65
30
67
31
73
26
95
2
25% Slope
South Aspect
1979
3
27
31
38
20
61
16
79
22
57
52
18
14
1980
2
39
47
9
46
16
40
13
46
11
29
2
(
1980
3
19
23
48
17
2
47
12
43
13
1
43
22
10
20
- This species category was not observed on line-transects used for analyses of vegetation.
4
-------
seasonal snowmelt alone; no supple-
mental irrigation was made. Only data
from the lower drains, below the
compacted zone, are discussed since
99% of the total volume of percolate was
collected from these drains.
Total cumulative volumes for all
treatments of both the high-elevation
lysimeter and low-elevation lysimeter
are shown in Table 3. Only the Paraho
retorted shale on the 25% slope of the
high-elevation lysimeter produced one
pore volume of leachate. Percolate
volumes from other treatments were
generally limited. The objective of
supplying additional irrigation water, on
a yearly basis, to the high-elevation
lysimeter was to evaluate the quantity
and quality of percolate which might
result from a processed oil shale
disposal pile at an elevation where
seasonal precipitation exceeded evapo-
transpiration and resulted in percolate.
After the initial leaching and irrigation
for plant establishment (which resulted
in a minimal amount of percolate) no
further irrigation was applied to the low-
elevation lysimeters. In these treat-
ments, the vegetation was able to
deplete the plant-available moisture in
the profiles of most treatments, allow-
ing a reservoir for spring recharge.
Consequently, a significant amount of
percolate did not result in later years.
Because of the limited percolate
volume from most treatments, the EC
values fluctuated considerably. The
maximum EC was not always associated
with the initial percolate from a particular
lysimeter, nor were minimum EC values
associated with the final percolate
flowing from a lysimeter. Overall,
however, a general drop in EC values
was observed for treatments through
which greater amounts of water had
passed, such as the Paraho retorted
shale, 25% slope, of the high-elevation
lysimeter. In 1977, maximum EC values
for leachate from this treatment were
31.0 mmhos/cm, dropped to 15.1
mmhos/cm by 1979, and returned to
23.9 mmhos/cm in 1980. Much greater
volumes of water leached through the
lysimeters would be required in order to
stabilize the chemical composition of
the percolate.
Laboratory analyses of the initial
percolate collected in 1977 are reported
in Table 4. Analyses for EC, pH, TDS,
and common cations and anions were
made in order to judge the quality of the
percolate.
The percolate collected from the
lower drains of the lysimeters had a
Table 2.
Water Quality Analyses of Spring Snowmelt Runoff from the
High-Elevation and Low-Elevation Lysimeters, North-Aspect. 2% Slope,
March 22, 1979
High-Elevation
Low-Elevation
20
cm Soil 40 cm Soil
Paraho
Runoff (cm)
pH
H6
0.22
6.9
EC (fjmhos/cm) 280
Na (meq/l)
Ca (meq/l)
Mg (meq/l)
K (meq/l)
C03 (meq/l)
HCO3 (meq/l)
N03 (meq/l)
S04 (meq/l)
Cl (meq/l)
SAR
Salinity Hazard
Sodium Hazard
0.7
0.9
0.9
0.2
0
1.3
0.3
0.7
0.5
0.7
low
low
Paraho
Paraho Retorted Shale
H10
0.17
7.1
620
2.1
1.0
1.0
0.5
0
2.2
O.02
2.6
1.8
2.1
low-med
low
Table 3. Total Percolate Volume from
Treatment
High Elevation
Paraho Spent Shale
20 cm Soil/Paraho
40 cm Soil/Paraho
60 cm Soil/Paraho
80 cm Soil/Paraho
Soil Control
Low Elevation
Paraho Spent Shale
20 cm Soil/Paraho
40 cm Soil/Paraho
60 cm Soil/Paraho
80 cm Soil/Paraho
Soil Control
Slope
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
2%
25%
1977
9,513.8
34,110.4
2,179.0
24,636.6
447.4
3,860.7
0
1,308.9
0
1,771.8
219.0
5,649.1
1,042.6
706.8
771.4
4,638.5
0
0
0
0
0
0
0
0
L4
0.16
7.3
280
0.6
0.6
1.8
0.2
0
1.6
0.06
1.3
0.5
0.6
low
low
the Lysimeter Study,
1978
4, 149. 1
8,527.6
462.5
8,658.2
1,092.7
5.969.0
107.1
2.879.6,
946.3
4,087.0
1,105.2
5.216.5
5.0
0
20.0
180.0
0
0
0
0
0
0
0
0
1979
.
903.1
7.171.8
223.7
5,969.3
817.6
5,059.0
0
2,487.9
199.1
3.384.2
12.0
4.0
15.0
0
5.0
60.0
0
0
0
0
0
0
0
0
80 cm Soil/
Paraho
L18
0.12
7.7
500
2.2
1.0
1.0
0.7
0
2.1
0.15
1.6
1.5
2.2
low
low
L20
0.26
7.4
390
1.3
1.0
0.6
0.3
0
2.1
0.03
1.0
1.0
1.4
low
low
1977-1980
1980
0
318.7
0
91.2
0
22.7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Total
14,566.0
50.128.5
2,865.2
39,355.3
7,357.7
14,911.4
107.1
6,676.4
1,145.4
9.243.0
1,336.2
10,869.6
1,062.6
706.8
796.4
4,878.5
0
0
0
0
0
0
0
0
-------
Table 4.
Laboratory Analyses of the Initial Percolate from the High-Elevation
Lysimeter, 1977
Percolate from Retorted Shale
Percolate from Soil
6/8/77 6/17/77 9/2/77 8/1/77 8/23/77 8/31/77
EC, ^mhos/cm
pH
TDS, ppm
SAP
Cations, meq/l
Ca
Mg
Na
K
An ions, meq/l
Cl
S04
12.983
6.3
14,328
52.8
16.4
9.0
148.8
11.2
30.6
157.7
27,222
7.1
31,984
116.8
23.0
5.1
429.3
45.1
28.2
449.6
10,500
7.0
*
30.0
17.4
1.5
90.0
11.3
4.8
119.0
4600
7.5
*
10.8
8.8
8.5
31.5
2.9
11.5
35.6
5100
8.2
*
3.7
6.9
21.4
36.1
1.1
17.1
37.5
5100
8.3
*
9.7
5.4
19.8
34.0
1.0
15.3
36.2
*Not determined.
high soluble salt content from passing
through 2.4 m of retorted shale. It can be
predicted from these values that water
moving through a retorted shale pile,
several hundred meters thick, could be
extremely saline.
Laboratory analyses also indicated
that the SAR of the percolate was high.
This suggested that the percolate could
create soil dispersion problems in
irrigated agriculture. The soil control
produced percolate with a moderate
SAR, increasing the possibility of a
sodium dispersion problem in such soils
if contaminated with retorted shale
percolate.
Water Balance
Water balance calculations were
made for all treatments of both lysim-
eters for the 1977 season (Harbert et al.,
1979). An attempt was made to account
for the total volume of water applied to
each treatment by estimating various
inputs and losses. Inputs of moisture
were fairly well defined and limited,
such as precipitation and irrigation.
Losses were more difficult to measure
and estimate, such as percolation,
moisture storage in the profile, and
evapotranspiration.
For all of the leached treatments,
amounts of water applied could not be
accounted for by a summation of losses
as they were measured or estimated. A
water balance for the unleached treat-
ments resulted in just the opposite, in
that water losses were calculated to be
greater than water inputs. The moisture
measurements for the soil control most
nearly balanced inputs and losses.
Other researchers have addressed the
problem of water balances for the
lysimeter study (Chandler, 1979).
Conclusions
Chemical and Physical
Characteristics of Paraho
Retorted Shale
1. After four wetting-and-drying cycles,
the pH of Paraho retorted shale
surface samples was reduced from
11.2 to 9.0.
2. After leaching, the Paraho retorted
shale soluble salt content was
reduced from 7.1 mmhos/cm to 3-4
mmhos/cm.
3. The unleached treatments averaged
approximately 10 mmhos/cm through-
out the retorted shale profile, al-
though, there was no indication of
upward migration of soluble salts by
1979.
4. Laboratory analyses of 1977 core
samples suggested that imbalances
of calcium, magnesium, and sodium
might inhibit plant growth on the
Paraho retorted shale.
5. Surface temperatures reach 80°C on
south slopes of the black-colored
Paraho retorted shale. This might be
lethal to seedlings, while increasing
surface evaporation.
Vegetation
1. After four growing seasons, peren-
nial vegetation on the Paraho reported
shale remained minimal (2% to 3%
cover).
2. A good to excellent vegetative cover
was established and maintained on
the soil control and soil-covered,
retorted shale treatments, with
western wheatgrass as the predomi-
nant species.
3. Differences between varying amounts
of soil cover, with respect to vegeta-
tive cover, were insignificant.
4. Shrubs seeded on the low-elevation
lysimeters were unable to signifi-
cantly increase in either number or
size over four growing seasons,
indicating limited root tolerance for
the Paraho retorted shale.
Percolate
1. Ninety-nine percent of the total
percolate collected from all treat-
ments was from the lower drain,
under the compacted zone.
2. Core samples taken later suggested
that moisture had moved through
both the uncompacted and com-
pacted profile.
3. Abrupt textural changes from the
fine-textured soil to the coarse-
textured Paraho retorted shale
below, delayed the uniform down-
ward movement of moisture through
the profile.
4. Irrigation (except for 1980) of the
high-elevation lysimeters resulted in
percolate each spring.
5. Only the treatments which had been
leached (Paraho retorted shale and
20-cm soil/Paraho retorted shale) of
the low-elevation lysimeters pro-
duced percolate.
6. On unleached treatments of the low-
elevation lysimeters moisture did not
move below 105 cm.
Water Quality
1. The maximum EC of percolate from
the Paraho retorted shale was 35
mmhos/cm.
2. Overall, a decrease in percolate EC
after four years was observed, how-
ever, EC values fluctuated consider-
ably.
3. If water moves through the Paraho
retorted shale a high pollution poten-
tial exists, with respect to EC and
SAR values measured.
4. Greater total pore volumes must
pass through the lysimeters before
the chemical composition of the
percolate stabilizes.
Disposal Pile Temperatures
1. The freshly retorted shale used in
this study maintained 60°C temper-
atures for 30 days.
2. Prolonged, elevated temperatures
could significantly affect both the
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amount and composition of vegeta-
tive cover on disposal piles.
Recommendations
1. Because of the unsuitability of the
Paraho retorted shale as a direct
plant growth media, soil cover is
recommended for successful estab-
lishment of vegetation on the retorted
shale.
2. Poor establishment and growth of
the fourwing saltbush suggested
limited root penetration into the
Paraho retorted shale. Additional
studies are needed to evaluate root
growth in retorted shale.
3. Efforts should be made to prevent
movement of water through the
retorted shale as leach water poses a
pollution potential due to high
soluble salt content.
4. Research is needed to insure that the
compacted shale can be made
impervious since, in this study,
moisture moved through Paraho
retorted shale compacted to a density
of 1.5 to 1.6 g/cm3.
5. Elevated temperatures maintained
in the retorted shale disposal pile
might adversely affect the establish-
ment of vegetation. Further investi-
gation under commercial disposal
pile conditions is recommended.
6. The present fluctuations in chemical
composition of leachate from the
lysimeters require that additional
pore volumes of water are needed to
evaluate leachate quality.
References
1. Harbert H.P., III, W.A. Berg, and D.B.
McWhorter. 1979. Lysimeter dis-
posal of Paraho retorted oil shale.
EPA-600/7-79-188, US EPA, Indus-
trial Environmental Research Labo-
ratory, Cincinnati, Ohio, 45268.
2. Chandler, R.L. 1979. Water and
chemical transport in layered porous
media. Ph.D. Dissertation, Fall,
Colorado State Univerisity, Ft. Collins,
Colorado.
3. Kilkelly, M.K., and W.L Lindsay.
1979. Trace elements in plants on
processed oil shale, pp. 191-253. In
Trace Elements in Oil Shale, W. R.
Chapell (ed) 1976-1979 PR, US DOE
Contract No. EY-76-S-02-4017.
M. K. Kilkelly, H. P. Harbert, III, and W. A. Berg are with the Department of
Agronomy, Colorado State University, Fort Collins, CO 80523.
E. R. Bates is the EPA Project Officer (see below}.
The complete report, entitled "Field Studies on Paraho Retorted Oil Shale
Lysimeters: Leachate, Vegetation, Moisture, Salinity, and Runoff, 1977-
1980," (Order No. PB 81-234 742; Cost: $9.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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