United States
Environmental Protection
Agency
0
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S7-81-139 Mar. 1982
Project Summary
Field Studies on USBM and
TOSCO II Retorted Oil Shales
Vegetation, Moisture,
Salinity, and Runoff,
1977-1980
M. K. Kilkelly, W. A. Berg, and H. P. Harbert, III '
Field studies were initiated in 1973
to investigate the vegetative stabiliza-
tion of processed oil shales and to
follow moisture and soluble salt
movement within the soil/shale pro-
file. Research plots with two types of
retorted shales (TOSCO II and USBM)
with leaching and soil cover treat-
ments were established at two loca-
tions: low-elevation (Anvil Points) and
high-elevation (Piceance Basin) in
western Colorado. Vegetation was
established by intensive management
including leaching, N and P fertiliza-
tion, seeding, mulching, and irrigation.
After seven growing seasons, a
good vegetative cover remained with
few differences between treatments,
with the exception of the TOSCO
retorted shale, south-aspect, which
consistently supported less perennial
vegetative cover than other treat-
ments. With time, a shift from peren-
nial grasses to dominance by shrubs
was observed. Rodent activity on
some treatments had a significantly
negative effect on vegetative cover.
After initial irrigation for establish-
ment, the vegetation was dependent
on seasonal precipitation. Spring
snowmelt resulted in recharge of
profiles to depths of 60 to 120 cm. By
fall, plant-available moisture was
depleted by evapotranspiration. Al-
though the fine-textured TOSCO
retorted shale usually produced the
greatest runoff of all treatments, the
surface runoff and sediment yields
were generally low due to the adequate
vegetative cover. Initially, some ac-
cumulation of soluble salts occurred
at the surface because of ineffective
leaching. With subsequent weathering
salinity decreased throughout the
entire profile of most treatments that
were observed. Recorded surface
temperatures of the black TOSCO
retorted shale were sufficiently high to
limit seedling establishment and
increase surface evaporation.
This report follows an initial report
by Harbert and Berg (1978) which
detailed the construction, establish-
ment techniques, and interpretation
of measurements from 1973 to 1976.
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
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shale reserves, consisting of over
64,750 square kilometers in Colorado,
Wyoming, and Utah, contained over 9.5
x 10131 (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 of oil/day) would
generate approximately 20,000 ha-m
per 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.
A part of the solution to the manage-
ment of processed shales would be the
rapid establishment of a satisfactory
vegetative cover on disposal piles.
Vegetation would stabilize the processed
shale by decreasing water and wind
erosion. Transpiration by vegetation
would also result in less moisture
available for deep percolation. Estab-
lishment of vegetation would also aid in
returning the area to a range and
wildlife habitat, and provide a more
aesthetic landscape.
To make reasonable predictions about
the environmental impact of an oil shale
industry, it is necessary to investigate
both the chemical and physical proper-
ties of the waste material. Factors
affecting the characteristics of the
retorted shale include the natural
variation, in the raw shale, the degree to
which the raw shale was crushed prior
to retorting and the retorting process
itself.
In addition to physical and chemical
characteristics of the retorted shale, the
location of the disposal sites in a region
of complex geomorphology and varied
climatic regimes will influence the
success of disposal management efforts.
Thus, the following studies were
initiated to evaluate intensive manage-
ment techniques for the vegetative
stabilization of processed oil shales.
Two locations were chosen to simulate
disposal sites (a low-elevation and a
high-elevation). Various leaching and
soil cover treatments were applied to
two types of processed shales (TOSCO II
and USBM). The objectives of this study
were to investigate surface stability and
to monitor moisture and soluble salts in
the treatment profiles.
Materials and Methods
Field studies were initiated in 1973 to
investigate the vegetative stabilization
potential of retorted oil shales. The
objectives were to examine surface
stability and soluble salt movement in
retorted oil shales. Two types of
processed shale, USBM and TOSCO II,
with various leaching and soil cover
treatments were used. Study plots were
established at two sites to simulate
conditions existing at proposed shale
waste disposal sites. The low-elevation
site at Anvil Points (1,700 m) has a
semi-arid climate and sparse natural
vegetation of low-elevation pinyon-
juniper woodlands. This site receives
approximately 30 cm of annual precipi-
tation. The vegetation types at the high-
elevation Piceance Basin site (2,200 m)
were high-elevation big sagebrush
shrubland and low-elevation pinyon-
juniper woodland. With an estimated
average precipitation annually of 40cm,
this site was very similar in climate,
elevation, and vegetation to the Colorado
Federal Oil Shale lease sites in the
Piceance Creek Basin.
Each research site contains a set of
3.3 m x 6.6 m plots with the following
treatments:
1. Leached TOSCO retorted shale.
2. Leached TOSCO retorted shale
with 15-cm soil cover.
3. Unleached TOSCO retorted shale
with 30-cm soil cover.
4. Leached USBM retorted shale.
5. Leached USBM retorted shale
with 15-cm soil cover.
6. Unleached USBM retorted shale
with 30-cm soil cover at the high-
elevation site or 60-cm soil cover
at the low-elevation site.
7. Soil control.
Each of the seven replicated treat-
ments had a north and a south exposure
on a 4:1 (25%) slope.
The two retorted shales used in this
study were products of retorting
processes developed by Tosco Corpora-
tion (TOSCO II) and the U.S. Bureau of
Mines (USBM). The TOSCO retorted
shale was black, silt loam material
retorted at the Colony Development
Operation near Parachute, Colorado.
The USBM retorted shale was black-
gray and contained approximately 60%
coarse particles (>2 mm) and 40% soil-
sized particles (<2 mm).
Because these shales were retorted
under experimental conditions, they
may not be representative of later
commercially produced material. Sev-
eral years between retorting and
initiation of these field studies allowed
some physical and chemical changes to
occur due to weathering. The USBM
shale was retorted earlier and may have
initially had a higher pH than when used
for these studies.
The soils for the experimental control
were classified as a calcareous silty clay
loam at the low-elevation site, and a
non-calcareous silt loam at the high-
elevation site.
Construction was completed at both
the high-elevation and low-elevation
sites in 1973. After filling operations,
the plots were outfitted with salinity
sensors buried at 20 and 50 cm depths.
Because of erratic readings, their use
was discontinued in 1978. Neutron
probe access tubes were also installed
to monitor moisture patterns to a depth
of 150 cm throughout the growing
season by neutron probe. A surface
runoff collection system provided
information on the quality and quantity
of runoff from spring snowmelt or
summer thunderstorms. A tipping-
bucket rain gauge and recorder at each
study site, as well as a hygrothermograph
(during the growing season) supplied
climatological data.
Those treatments requiring leaching
were sprinkler irrigated after construc-
tion. The low-elevation site, leached
treatments, received a total of 100 cm of
water. The high-elevation site, leached
treatments, were irrigated by hauling
water on an intermittent basis. Because
of the high evaporation rate and low
application rate leaching was generally
ineffective and salinization of the
surface occurred at the high-elevation
site. Additional irrigation of 100 cm in
1975 applied continuously by sprinkler
succeeded in leaching the soluble salts
from the surface at this site.
After leaching, nitrogen and phos-
phorus fertilizers were applied to alT
treatments at both study sites. Phos-
phorus was incorporated to a depth of
10 cm at the rate of 400 kg P/ha in the
form of triple superphosphate. Nitrogen
was applied following germination at
the rate of 66 kg N/ha as ammonium
-------
nitrate. Supplemental maintenance
nitrogen was applied in following years
by broadcasting 66 kg N/ha when
spring regrowth began. Fertilization
with nitrogen was discontinued in
1979.
The low-elevation study site was
seeded in June 1973 with a mixture of
native grasses and shrubs. After lightly
raking, a mulch of grass hay was applied
and held with cotton netting. Although
the high-elevation site was initially
seeded in 1974, because of the salinity
problems mentioned, this site was
rototilled and reseeded in June 1975.
Irrigation aided the establishment of
vegetation at both study sites in the first
growing season. The low-elevation site
received a total of 46 cm of water, while
the high-elevation site received approx-
imately 20 cm of water for stand
establishment. Neither study site re-
ceived any additional irrigation in fol-
lowing seasons, but was dependent
upon naturally occurring precipitation.
Core samples were taken from 1973
through 1975. In later years, the plots
were core sampled on an intermittent
basis to minimize disturbance. Salinity
measurements on a 1:1 by weight, soil
to water ratio, were performed on 15 cm
increments of the core samples. A
saturated paste extract was not used
because of the large sized sample
required, as well as the physical charac-
teristics of the retorted shales.
Two methods of vegetative measure-
ments were used. The quadrat method
was used to provide an estimate of
germination and establishment the first
two years after seeding. The line-
intercept method was used in later'
years to provide a more quantitative
measurement. In 1976, the low-eleva-
tion study site was analyzed for total
above ground standing biomass.
A tipping bucket rain gauge with a
continuous chart recorder was installed
at both high- and low-elevation study
sites. These gauges were not wind
shielded, therefore, loss of precipitation
in the form of snow during winter
months was expected. A cylinder type
precipitation gauge at this site measured
approximately double the precipitation
recorded by the tipping bucket gauge,
January through April 1978, when
snow was a major form of precipitation.
Evidently, the tipping bucket gauge,
even though correctly calibrated, did not
adequately register annual precipitation
in the form of snow.
A more detailed account and descrip-
tion of the construction and measure-
ments for 1973 through 1976 was
presented in an earlier report (Harbert
and Berg, 1978).
Results and Discussion
Precipitation
Precipitation data for 1976-1980 are
reported for both study sites in Table 1.
The average annual precipitation for the
low-elevation study site was estimated
to be 30 cm, while that for the high-
elevation was estimated to be 40 cm.
Almost all of Colorado was subjected to
a drought during the 1976-1977 winter
season. Lack of snowfall, combined
with low spring precipitation, resulted
in considerable moisture stress to
vegetation at both study sites. Precipita-
tion for the summer months was also
unusually low at the high-elevation site
for 1978.
Low-Elevation Study Site
Vegetation
Over the 1973-1976 growing period, an
adequate stand of native perennial
grasses and shrubs was established
(Harbert and Berg, 1978). The applica-
tion of water for leaching and establish-
ment in 1973 provided a reservoir of
moisture in the soil or retorted shale
profiles for plant use. Only after the
1975 growing season were the moisture
recharge and extraction patterns de-
pendent upon the natural precipitation.
Because of this, 1976 vegetation data
has been used in this report as a
comparison for vegetation changes in
later growing seasons.
In 1976, there was an adequate stand
of native perennial species on all
treatments except for the TOSCO
retorted shale which was dominated by
annuals (Table 2). Overall, north slopes
supported more vegetation than drier
south slopes. Below average precipita-
tion over the 1976-1977 winter com-
bined with a drought during the 1977
growing season resulted in significantly
less vegetative cover on all treatments
in 1977. With a return to nearly average
precipitation in 1978 and 1979, the
vegetation recovered and reached
levels comparable to that before the
drought.
The most noticeable change over the
1976-1980 growing period was the
change in species composition from a
population dominated by perennial
Table 1. Monthly Precipitation for the Low- and High-Elevation Study Sites, 1976-1980
Low-Elevation Site
High-Elevation Site
Month
1976
1977
1978
1979
1980
1976
1977
1978
1979 1980
January
February
March
April
May
June
July
August
September
October
November
December
Total
0.4
5.9
3.7
3.4
4.0
1.8
1.2
2.5
3.8
1.4
0.1
0.1
28.3
1.5
0.6
2.2
0.9
1.5
0.5
-
4.8
3.7
2.2
-
2.5
20.4
4.8
3.5
9.2
3.4
2.6
0.6
0.2
1.1
2.0
0.1
5.1
2.9
35.5
0.7
4.5
3.3
0.6
4.1
1.2
1.7
3.3
0.4
2.0
3.0
0.6
25.4
Cl
5.5
9.2
5.9
2.1
6.4
0.0
3.0
2.2
0.6
4.8
1.5
1.6
42.8
77
5.1
7.1
O.6
3.4
5.2
2.5
1.2
3.4
2.2
0.7
0.1
0.1
31.6
1.0
1.3
2.0
3.5
1.4
0.5
3.4
3.9
3.5
2.3
1.9
0.7
25.4
1.3
1.0
2.8
2.7
3.7
0.6
0.5
0.6
0.2
0.3
1.4
0.3
15.4
0.5
0.4
1.3
0.6
6.0
0.7
0.9
2.9
0.4
3.3
1.4
0.6
19.0
1.2
1.7
3.5
1.4
2.8
0.0
2.9
2.6
1.2
2.9
0.3
0.9
21.4
- Incomplete data.
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grasses to one dominated by shrubs
(Table 2). The south slopes showed a
greater decrease in perennial grasses
and a greater increase in shrubs than
did the north slopes. Most of the shrub
cover increase was due to the large
spreading canopy of fourwing saltbush
which increased in size every growing
season. Although some increase in
shrub cover was measured on the north
slopes, the persistence of perennial
grasses, primarily western wheatgrass,
was greater than on south slopes.
Overall, the TOSCO retorted shale
consistently supported less perennial
Table 2. Vegetative Cover by Species Categories for the Low-Elevation Study Treatments. 1976-1980
Treatment Species Categories 1976 1977 1978 1979
1980
TOSCO Spent Shale
15 cm Soil Cover/TOSCO
30 cm Soil Cover/TOSCO
USBM Spent Shale
15 cm Soil Cover/USBM
60 cm Soil Cover/USBM
Soil Control
TOSCO Spent Shale
15 cm Soil Cover/TOSCO
30 cm Soil Cover/TOSCO
USBM Spent Shale
15 cm Soil Cover/USBM
60 cm Soil Cover/USBM
Soil Control
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
NORTH ASPECT
28
13
52
73
4
15
53
17
14
62
14
17
85
16
1
66
24
7
78
18
2
SOUTH ASPECT
23
21
22
66
5
7
45
37
5
40
21
11
50
23
6
53
24
3
79
19
1
21
6
<1
28
5
<1
25
13
<1
52
10
<1
39
16
<1
28
12
<1
28
22
<1
8
24
<1
14
9
<1
13
45
<1
13
32
<1
6
21
<1
18
31
<1
16
7
<1
%
33
23
55
52
13
43
44
9
5
39
15
28
61
16
4
47
30
11
65
17
10
6
17
35
30
18
28
17
57
15
15
47
6
15
40
14
37
31
14
40
19
22
16
27
29
45
15
25
42
14
30
40
17
30
63
28
6
48
41
14
53
23
20
12
34
6
37
27
22
17
56
10
11
50
18
18
52
12
37
26
13
56
11
10
12
24
15
36
10
12
29
23
13
17
33
15
27
19
7
20
30
15
31
30
10
6
55
32
13
31
20
7
36
23
6
34
21
5
50
16
11
44
17
21
13
13
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vegetative cover than the USBM re-
torted shale, soil cover treatments, or
the soil control. This was believed, in
part, to be a reflection of the reduction in
perennials caused by the resalinization
in 1973 of the TOSCO profile after
leaching. Measured surface tempera-
tures indicated that evaporation of
moisture from the black TOSCO mate-
rial could have also significantly affected
the vegetation. Runoff has also been
greater on the TOSCO retorted shale
due to the silty texture creating slow
infiltration and resulting in less moisture
recharge of the profile. All of these
factors have probably contributed to
less perennial vegetation cover on the
TOSCO retorted shale. Vegetative
analysis by individual species is re-
ported in the appendix to this report.
Moisture in Retorted Shale
and Soil Treatments
Spring measurements in 1976 re-
vealed a large reservoir of plant-avail-
able moisture in all treatments. Residual
moisture from establishment irrigations
was most likely responsible for the
considerable amount of moisture mea-
sured (25% to 30% by volume). By fall,
plant-available moisture was depleted
to a depth of 90 cm to 120 cm, with
moisture use greatest on the USBM
retorted shale treatments. The least
amount of water used was by plants
growing on the TOSCO retorted shale.
Overwinter precipitation, from October
of 1976 through 1977 growing season,
was considerably less than average for
this study site. For this reason, recharge
of the moisture profiles was minimal.
Consequently, plant-available water
was limiting. The north-aspect of
TOSCO retorted shale showed the most
water lost throughout the growing
season. Water losses were slight to
insignificant on all other treatments.
With the return to more normal
precipitation during the winter of 1977
and spring of 1978, recharge of the
moisture profiles for all treatments
averaged 25% moisture by volume.
Water losses throughout the growing
season were similar for both USBM and
TOSCO treatments. The soil control
showed the least amount of water lost,
most probably due to the absence of
fourwing saltbush on this treatment.
Patterns of recharge and depletion in
the moisture profiles for 1979 mea-
surements were very similar to 1978
values. In 1980, recharge from spring
snowmelt averaged 20% to 25% mois-
ture by volume, which, by the end of the
growing season was depleted to approx-
imately 10% moisture by volume. Once
again, the soil control averaged the least
amount of water lost from its profile,
probably due to the lack of large shrubs
on the treatment.
After seven growing seasons, the
vegetative composition on these treat-
ments is fairly stable. The large four-
wing saltbush shrubs currently domi-
nating the vegetation will most likely
continue to extract substantial amounts
of water from the moisture profiles of all
treatments. If overwinter precipitation
is average, the recharge and extraction
patterns of both USBM and TOSCO
retorted shale should continue to
provide adequate plant-available mois-
ture to support the present vegetative
cover.
Leaching and Movement of
Soluble Salts
Soluble salts in the TOSCO retorted
shale extracts, before leaching, averaged
about 18 mmhos/cm. Immediately after
leaching in early 1973, the EC values
fell to around 5 mmhos/cm, butduetoa
combination of factors, the profiles of
the TOSCO retorted shale were resali-
nized by the fall of 1974 (Harbert and
Berg, 1978). A large reservoir of
subsurface moisture, the movement of
that moisture along with dissolved salts
upward, and rapid surface evaporation
from the black material combined to
cause the resalinization. The concentra-
tion of salts at the shale surface was
particularly noticeable, with EC values
of shale extracts reaching 15 to 17
mmhos/cm. Soluble salts did not
accumulate at the surface of the TOSCO
shale treatments which had not been
leached because subsurface water in
excess of field capacity was not available
to transport dissolved salts upward.
Core samples taken in subsequent
years indicated that additional moisture
from winter and spring precipitation
was effective in moving the soluble salts
downward within the profile. Although
when sampled in 1978, there was a
small overall increase in salinity through-
out the entire profile of the TOSCO
shale plots, which was likely due to
leaching of soluble salts from large
particles of the processed shale. Further
precipitation and continued weathering
of the shale particles resulted in an
overall decrease of salinity throughout
the entire profile of the TOSCO shales
by 1980. This, combined with a satisfac-
tory vegetative cover which effectively
utilized moisture from the profile,
should reduce the potential for upward
movement of water and dissolved salts.
The salinity hazard of the USBM shale
was initially less than the TOSCO shale,
and after the 1973 leaching, has
continued to remain at an acceptable
level. Resalinization of the USBM
shales did not occur, probably because
of the coarse texture of this material,
which restricted upward capillary
movement.
The soil control was non-saline
originally and no salt accumulation was
observed during the study period.
Runoff and Water Quality
Surface runoff has primarily been the
result of spring snowmelt, although
occasional summer thunderstorms
have resulted in measureable surface
runoff. Volume of runoff, sediment
yields, conductivity, and chemical
analyses are presented in the full report.
Runoff and water quality data for the
1973-1976. period were reported in
Harbert and'Berg (1978).
Overwinter precipitation for 1976-
1977 was severely limiting, resulting in
no measurable spring snowmelt runoff
except for one north-aspect, 15-cm soil
cover/TOSCO plot. Runoff calculated
from this plot only amounted to 0.02 cm.
In September of 1977, two separate
summer thunderstorms produced lim-
ited runoff on a few treatment plots. The
only significant runoff was confined to
the TOSCO retorted shales and was
ranked as. posing a low salinity hazard.
Sediment yields from the TOSCO shale
treatments were highest, but when
compared to agricultural soils, were
small. Caution must be used in inter-
preting these data as it has been
observed that small amounts of runoff
dissolved salts concentrated at the
surface. Larger amounts of runoff
simply diluted these salts, decreasing
the salinity hazard of the runoff water.
In 1978, spring snowmelt produced
runoff primarily restricted to the various
TOSCO shale treatment plots. With
small amounts of runoff, the salinity
hazard was rated moderate to high for
most treatments. Sediment yields were
considered minimal.
A larger amount of spring snowmelt
runoff in 1979 was rated as having a
low salinity hazard with nominal
sediment yields.
Spring snowmelt in 1980 produced
runoff only on frozen north-aspect
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slopes. Because a thin layer of ice
remained over the frozen ground, the
water quality of the runoff posed no
environmental hazard.
The well-developed vegetative cover
on all treatments at this site will most
likely minimize excessive runoff and
erosion in future seasons. Runoff from
spring snowmelt will depend primarily
upon whether the ground surface is
frozen or thawed, butwaterqualityfrom
a frozen surface should not present
environmental problems. This type of
runoff will, however, limit the amount of
moisture that infiltrates the profile to be
used by vegetation later.
Surface Temperatures
Temperatures! cmbelowthesurface
of TOSCO shale and soil plots, for both
north and south aspects were monitored
during the 1978 growing season.
Previous data (Harbert and Berg, 1978)
had shown temperatures sufficiently
high in late June and July on the TOSCO
shale, south-aspect, to limit seedling
establishment. The 1978 measurements
continued to support these findings.
Initial establishment of vegetation
without the protection of a mulch could
be difficult, and the successful germina-
tion of seedlings in continuing years
might depend upon the shade provided
by an adequate mature vegetative
cover. Evaporative losses could also be
substantial, creating a difficult revege-
tation site.
High-Elevation Study Site
Vegetation
Because of ineffective leaching of
some treatments in 1974, an unsatis-
factory stand establishment resulted.
All plots at this study site were releached,
reseeded, and irrigated for establish-
ment in 1975. Therefore, 1976 was the
first growing season dependent upon
natural precipitation, although it was
likely that some moisture remained in
the soil profile due to leaching.
Initially, a satisfactory vegetative
cover was established in 1975, with
dense stands of western wheatgrass on
the TOSCO and USBM retored shales.
This was probably due to the effective
leaching and doubled seeding rate of
western wheatgrass.
Very little overwinter precipitation
and an abnormally dry growing season
in 1977 combined to reduce the vegeta-
tive cover on almost all treatments.
Shrubs endured the drought better than
perennial grasses, the former actually
increased on USBM retorted shale.
Annual species dropped to less than 1 %
on all treatments due to lack of moisture
(Table 3).
In the fall of 1977, cattle accidentally
entered the study site and grazed much
of the vegetation. Because of adequate
moisture for plant regrowth, the overall
1978 vegetative cover was not severely
reduced despite heavy grazing of
fourwing saltbush. With more moisture,
annual species were measured in
modest amounts, particularly on the soil
control.
Another season of sufficient moisture
increased the vegetative cover on
almost all treatments in 1979. Unfortu-
nately, a large amount of this increase
was due to the invasion of annual
species such as cheatgrass and mustard
(Table 3). The increase of annuals may
have also been aided by the shift from a
population of mainly perennial grasses
to one increasingly dominated by
shrubs. This transition was especially
noticeable on the USBM retorted shales
where rodent disturbances also allowed
the invasion of annuals.
During the 1980 growing season,
rodent activity increased, disturbing
large areas of many treatment plots and
resulting in an overall decrease of
vegetative cover. Most of this decrease
was attributable to the loss of perennial
grasses on many treatments (Table 3).
The invasion of weedy species also
accompanied this disturbance.
Generally, for the years discussed,
the overall vegetative cover for both
TOSCO and USBM shales was compa-
rable to the soil control. In retrospect,
the doubled seeding rate of western
wheatgrass on those two treatments
provided an initial cover which exceeded
that of the soil control. After a severe
drought season in 1976-1977, vegeta-
tion on both shale treatments recovered
well. However, the species composition
of the shale treatments supported a
much greater proportion of cover as
shrubs than the soil control, a trend
which is expected to continue in future
growing seasons.
Moisture in Retorted Shale and
Soil Treatments
Spring snowmelt generally provided a
maximum moisture recharge of treat-
ment profiles. During the growing
season, vegetation extracted plant-
available moisture from the treatment
profiles resulting in a depletion by fall.
Moisture profiles of almost all treat-
ments in 1976 contained residual
moisture from 1975 irrigation applica-
tions. One exception seemed to be the
USBM treatment on north slopes. Very
little recharge from spring snowmelt
occurred because of the high surface
runoff for these plots (Harbert and Berg,
1978). In fact, precipitation during the
1976 growing season, combined with a
less than average vegetative cover,
produced an overall increase in plant-
available water by the fall of 1976.
Very limited overwinter precipitation,
from October 1976 through March
1977, resulted in a minimal spring
recharge of moisture profiles. Because
of the lack of plant-available water,
vegetative growth on almost all treat-
ments suffered, resulting in very little
water loss throughout the profile.
Although precipitation for the 1977-
1978 winter period was below average,
spring recharge for 1978 averaged
approximately 20% by volume for USBM
treatments. Most of these treatments
were recharged to a depth of 90 cm. The
TOSCO retorted shale averaged only
10% to 15% moisture by volume to 60
cm depths. This may be a reflection of
the higher surface runoff from the latter
treatments. Spring recharge was great-
est on the soil control, averaging 20% to
25% moisture by volume. Water loss
throughout the growing season was
also greater on the soil control, resulting
in only about 10% moisture by volume
remaining in the profile by fall of 1978.
Moisture extraction patterns on all
other treatments were similar.
Near average precipitation permitted
a 1979 spring recharge of 20% to 25%
soil moisture by volume on all treat-
ments. Large amounts of runoff from a
TOSCO retorted shale, south-aspect,
plot did not seem to adversely affect
spring recharge. Once again, the soil
control averaged the highest spring soil
moistures, and the most water lost from
the profile through the growing season.
Moisture measurements taken in the
fall of 1979 indicated depletion to
approximately 10% on most treatments,
while the TOSCO retorted shale aver-
aged 6% moisture by volume.
Seasonal moisture profiles for 1980
followed much the same patterns as in
previous years. Recharge from a greater
than average snowfall brought most
treatments to 20% to 30% moisture by
volume capacity to depths of 60 cm to 90
cm.
-------
Table 3. Vegetative Cover by Species Categories for the High-Elevation
Treatment Species Categories 1976
TOSCO Spent Shale
15 cm Soil Cover/TOSCO
30 cm Soil Cover/TOSCO
USBM Spent Shale
15 cm Soil Cover/USBM
30 cm Soil cover /USBM
Soil Control
TOSCO Spent Shale
15 cm Soil Cover/TOSCO
30 cm Soil Cover/TOSCO
USBM Spent Shale
15 cm Soil Cover/USBM
30 cm Soil Cover/USBM
Soil Control
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
Perennial Grasses
Shrubs
Annuals
NORTH ASPECT
68
21
6
48
13
7
40
9
7
60
20
2
48
7
11
29
13
17
41
16
14
SOUTH ASPECT
61
16
2
45
12
4
42
23
7
41
32
3
39
16
16
28
24
18
28
22
19
Study Site.
1977
38
12
<1
42
7
<1
38
<7
<1
40
30
<1
44
10
<1
42
12
<1
38
12
<1
49
23
<1
39
15
<1
38
23
<1
21
37
<1
38
17
<1
26
19
<1
25
17
<1
1976-1980
1978
%
43
9
12
52
21
2
54
9
5
24
32
3
56
23
2
42
24
7
43
9
12
31
23
<1
45
15
<1
41
10
8
24
36
<1
40
27
8
39
17
3
42
14
12
1979
44
33
0
59
22
3
47
3
32
21
51
7
35
38
7
29
34
29
41
14
44
28
30
9
54
21
0
40
11
30
16
43
0
21
38
30
17
31
34
24
16
52
1980
22
18
1
26
11
1
38
2
11
6
48
5
12
31
1
9
28
12
26
9
11
16
14
17
19
14
1
9
29
2
3
49
14
6
40
11
5
39
19
9
13
19
-------
Overall, it appeared that moisture
recharge by spring snowmelt was
significantly affected by the fine-
textured TOSCO material, due to high
runoff rates. The coarser textured
USBM shale allowed faster infiltration
of snowmelt which resulted in greater
spring moisture levels.
Leaching and Movement of
Soluble Salts
Core samples taken after leaching of
the retorted shales and 15-cm soil
cover/retorted shales in the fall of 1973
indicated that a reduction of salinity had
not occurred. The leaching technique
used was ineffective because the
application of the irrigation water did
not exceed the surface evaporation to
the extent that soluble salts were moved
a satisfactory depth in the profile. In the
spring of 1974, all previously leached
treatments were releached to decrease
the salinity hazard of the shale. Resali-
nization of the TOSCO retorted shales
once again occurred, primarily at the
shale surface. Another application of
leach water was made to all leached
treatments in the spring of 1975. Core
samples after leaching indicated that
effective leaching had occurred through-
out the profile with accompanying EC
values of less than 5 mmhos/cm.
The TOSCO shale treatments covered
with 30 cm of soil were never leached,
and therefore, continued to maintain a
higher salinity level then the leached
treatments.
Core samples taken in 1978 suggested
that the TOSCO shale treatments had
become slightly more saline with time,
although shale extracts only averaged
about 5 to 7 mmhos/cm in the leached
treatments, and 10 to 12 mmhos/cm in
the unleached treatments. This increase
was most likely due to the leaching of
soluble salts from within shale particles.
Increased weathering of the shale
materials, combined with seasonal
precipitation resulted in an overall
decrease of salinity throughout the
entire profile of the TOSCO shales by
1980. Of particular interest was the
downward movement of soluble salts in
the 30-cm soil/unleached TOSCO
shale treatments.
The USBM shale extract values were
initially less saline than the TOSCO
shale material, and with additional
leaching have become acceptable with
no indication of resalinization in suc-
ceeding years. Little or no change was
observed in the salinity status of the soil
control throughout the study.
Yearly precipitation and the rapid
removal of subsurface water by the
established vegetation cover should
limit any upward resalinization.
Runoff and Water Quality
All runoff and water quality data for
the 1974-1976 period of study were
reported in Harbert and Berg (1978).
Runoff, sediment yield, conductivity,
and chemical analyses for 1977-1980
measurements are presented in the full
report.
Runoff in the spring of 1977 was
confined to the north aspect slopes of all
treatments. Thiswas mainly a reflection
of the very limited overwinter precipita-
tion for this year. In August of 1977, a
thunderstorm produced small amounts
of runoff on almost all treatment plots
ranging from 0.02 to 0.12 cm. Salinity
hazard was lowfor most treatments, but
the TOSCO retorted shale runoff was
rated as medium to high. One USBM
retorted shale plot also produced runoff
with a high salinity. Due to the small
amount of runoff, surface salts were
dissolved and removed by the initial
runoff. Without additional runoff to
dilute this concentrated salt solution,
salinity hazards were high. This was
clearly illustrated by the 1978 spring
snowmelt runoff and analyses. Runoff
from both USBM and TOSCO shale
south slopes was minimal in quantity
but had a very high salinity hazard,
whereas runoff from the north slopes of
these two treatments was approximately
three times the volume, but the salinity
hazard was considerably less. Sediment
yields were considered negligible when
compared to regional sediment yields
mapped by the Soil Conservation
Service.
In 1979, spring snowmelt runoff had
low salinity hazard, minimal runoff, and
small sediment yields.
In 1980, spring runoff was generally
small in volume and rated low with
respect to salinity hazard, sodium
hazard, or sediment yield.
At present, runoff, erosion, and
salinity hazards from the treatments are
within acceptable levels. The most
critical environmental factor appears to
be the salinity hazard of small amounts
of runoff from the retorted shale. This
type of runoff is associated with limited
snowmelt runoff or summer thunder-
storm activity typical of this region. As
far as revegetation efforts , the spring
snowmelt runoff poses a problem in that
moisture from snowmelt that runs off
does not enter the shale or soil profile.
and therefore, is not available for plant
growth needs. The satisfactory vegeta-
tive cover on jnost treatments minimized
runoff and erosion. The increased
rodent activity causing surface distur-
bance may develop the potential for
greater runoff and erosion.
Conclusions
Low-Elevation Study Site
Vegetation
1. After seven growing seasons, a
good vegetative cover (52% to
68%) existed on all treatments.
2. The TOSCO retorted shale, with
no soil cover, generally supported
less perennial vegetation through-
out the years than other treat-
ments.
3. A shift in vegetative composition
from perennial grasses to predom-
inance by xeric shrubs occurred on
all treatments.
Moisture
1. With average seasonal precipita-
tion, most treatment profiles were
recharged to levels of 20% to 25%
moisture by volume in the spring
to depths of 60-120 cm.
2. Good vegetative cover, especially
deeper-rooted shrubs, extracted
substantial moisture from all
treatment profiles to approximate-
ly 10% moisture by volume by fall.
3. South-facing slopes reflected a
drier soil moisture regime than
north-facing slopes by a more
rapid shift from grasses to xeric
shrubs.
Salinity
1. Leached treatments of the fine-
textured TOSCO shale initially
experienced some accumulation
of surface salts, and salinization of
soil covers over retorted shale.
2. Seasonal precipitation in later
years reduced salinity levels to 5
mmhos/cm or less throughout the
entire profile of leached treatments
with no indication of upward salt
migration.
Runoff and Water Quality
1. The quantity and quality of spring
snowmelt runoff depended on
whether the ground surface was
frozen or thawed.
2. A greater runoff volume resulted
when the ground surface was
frozen and this runoff was of
higher water quality.
8
-------
3. Small amounts of runoff in 1978
were rated medium to very high
salinity hazard (1210 - 3200
umhos/cm).
4. The use of a mulch during vegeta-
tive establishment and the present
vegetative cover contributed to
low sediment yields for all treat-
ments. Sediment yields from the
TOSCO shale treatments were the
highest, but even these were
small when compared to agricul-
tural soils.
High-Elevation Study Site
Vegetation
1. The initial vegetation established
in 1974 was unsatisfactory be-
cause perennial grasses were
seeded at a low rate, a too dense
stand of big sagebrush resulted,
and the inadequately leached
retorted shales were resalinized.
2. After releaching, rototilling and
reseeding, a good stand resulted.
3. Rodent activity, particularly pocket
gophers, caused considerable
surface disturbance resulting in a
loss of vegetative cover.
4. A shift from perennial grasses to
predominance by xeric shrubs was
observed.
Moisture
1. Spring snowmelt resulted in re-
charge of profiles to depths of 60-
120 cm.
2. Evapotranspiration resulted in
depletion of plant-available mois-
ture in the profiles by fall.
Salinity
1. Due to high evaporative demand
and low irrigation rates, resalini-
zation of the leached layer over the
retorted shales resulted in 1974.
2. Resalinization did not occur after
the 1975 releaching.
3. Seasonal precipitation and con-
tinued weathering reduced soluble
salts to 5 mmhos/cm or less
throughout the entire profile of
leached treatments by 1980, with
no indication of upward salt
movement.
Runoff and Water Quality
1. Spring snowmelt was responsible
for the majority of surface runoff
on all treatments.
2. When small amounts of runoff
resulted, from either limited snow-
melt or summer thunderstorms,
the salinity hazard was rated high
to very high from the retorted
shales (1120 - 7200 umhos/cm).
3. The sodium hazard and sediment
yields were rated low for runoff
from all treatments.
Recommendations
1. Intensive management will be
required to establish a satisfactory
vegetative cover within a reason-
able amount of time.
2. As a specific retorting method
develops, investigation of the
waste as a plant growth media
requires a thorough examination
of the physical and chemical
characteristics of the retorted
shale.
3. The eventual erosion of soil cover
or modified retorted shale, partic-
ularly from steep south-facing
slopes, could result in continued
exposure of less weathered re-
torted shale. This should be
considered in future waste stabili-
zation research and planning.
4. The ultimate fate of applied leach
water, along with a comprehensive
water balance (especially for high-
elevation disposal sites) should be
addressed.
5. Large herbivores were restricted
from the small plots in this study
by fencing, future research should
evaluate both wildlife and domestic
livestock use on the retorted shale
disposal site.
6. The retorted shale disposal site
stabilization plan must allow for
localized severe rodent distur-
bances as observed in this study.
References
1. Harbert, H. P., Ill, and W. A. Berg.
1978. Vegetative stabilization of
spent oil shales. EPA-600/7-78-
021, U.S. Environmental Protection
Agency, Industrial Environmental
Research Laboratory, Cincinnati,
Ohio.
M. K. Kilkelly, W. A. Berg, and H. P. Harbert. Ill, are with the Department of
Agronomy, Colorado State University, Fort Collins, CO 80523.
Edward R. Bates is the EPA Project Officer (see below).
The complete report, entitled "Field Studies on USBM and TOSCO II Retorted Oil
Shales: Vegetation, Moisture, Salinity, and Runoff, 1977-1980." (Order No.
PB 82-109 810; Cost: $11.00, 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
U. S. GOVERNMENT PRINTING OFFICE: 1982/559-092/3379
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