Soil water and solute movement in Montana strip mine spoils
by Franklin Brooks Arnold
A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE
in Soils
Montana State University
© Copyright by Franklin Brooks Arnold (1976)
Abstract:
A study was initiated in November, 1974 at the Peabody Big Sky Mine near Colstrip, Montana to
determine soil water and solute movement in strip mine spoils. Three spoils treatments, consisting of
topsoiled nonvegetated, topsoiled revegetated and nontopsoiled revegetated spoils, and a native range
site were studied.
The testing and evaluation of an unsaturated soil water movement model showed the model to be
applicable to soil water movement in both the mine spoils and native range.
Calculation of in situ soil water budgets indicated drainage was occurring from the spoils and native
range. Both the water movement model and the in situ water budgets indicated that the quantities of
soil water movement in the native range was approximately 1.5 times greater than in the spoils.
The lower amount of soil water movement in the spoils was attributed to bulk density, which was 54%
higher than native range, and to higher contents of silt and clay than native range. Clay mineralogy
analyses indicated that the dominant clay minerals in all treatments were non-expanding lattice clays,
which would not greatly limit soil water movement due to expansion upon wetting.
Infiltration rates of the native range were 60-86% higher than those of the spoils. These differences
were attributed to the effects of soil structure, vegetation and topsoiling techniques.
Saturated hydraulic conductivity of the native range was 3.5 times greater than that of the spoils
treatments. The higher hydraulic conductivity of the native range was attributed to textural differences
between the native range and spoils treatments.
No definite trends in solute movement were shown due to the short time span of this study. With the
exception of potassium and NCL-N, the solute concentrations of the spoils were not, in general,
different from the native range. The spoils contained lower potassium and higher NO3-N
concentrations than present in the native range. Exchangeable sodium percentages (ESP) and sodium
adsorption ratio (SAR) indicated no sodium problems were present in the spoils and native range.
The higher quantities of soil water movement in the native range compared to the spoils indicate that
greater amounts of solute movement into the groundwater may occur from the native range than from
the spoils. SOIL WATER AND SOLUTE MOVEMENT IN MONTANA
STRIP MINE SPOILS
by
Franklin Brooks. Arnold
A thesis submitted in partial fulfillment
of the requirements for the degree
of
MASTER OF SCIENCE
in
Soils
CV-cHair^fson, G^adu^e Committee
Co-chairperson, Gradiiafe Committee
Head, Major Department
Graduate
MONTANA STATE UNIVERSITY
Bozeman, Montana
\
November, 1976
■STATEMENT OF PERMISSION TO COPY
In presenting this thesis in partial fulfillment of the
requirements for an advanced degree at Montana State University,
I' agree that the Library shall make it freely available, for
inspection.
I further agree that permission for extensive copying
of this thesis for scholarly purpose may be granted by my major
professor, or, in his absence, by the Director of Libraries.
It.
is understood that any copying or publication of this thesis for
financial gain shall not be allowed without my written permission.
Signature
Date
JfovemkezL £ 3 ,
iii
ACKNOWLEDGEMENTS
The author wishes to express his appreciation to the encourage­
ment and understanding in every phase of his project from his wife,
Bellena.
Special appreciation is due to Drs. Douglas Dollhopf and
Hayden Ferguson for their guidance and valuable suggestions through­
out this investigation and manuscript preparation.
The author also
would like to thank Dr. Ervin Smith and Richard Kuntz for their time
and effort in assisting with the reduction of the data on the
computer.
Lastly, the author thanks the Peabody Coal Company for
funding of this investigation and for use of their Big Sky Mine
property and. facilities. .
TABLE OF CONTENTS
Page .
V I T A .................................. ............. ' ..........
ii
ACKNOWLEDGEMENTS................ .. . . ........................ iii
LIST OF TABLES .................................................
LIST OF F I G U R E S ...............
LIST OF APPENDICES . ...........................................
ABSTRACT ........................................
yi
vii
x
xiv
INTRODUCTION .........................■...........................
I
LITERATURE R E V I E W ......................................
3
METHODS AND MATERIALS
9
..........................................
Site Description and D e s i g n ......................... .. . . .
Neutron Probe Calibration .......... .............. . . . . .
Unsaturated Soil Water Flow ....................
In Situ Unsaturated Soil Water Budget . . . . . ..............
Soil Physical Measurements..............................
Clay M i n e r a l o g y ...........
Infiltration R a t e s .............
Saturated Hydraulic Conductivity ..............
Solute M o v e m e n t ....................
RESULTS AND DISCUSSION
Neutron Probe Calibration ..........
Unsaturated Soil Water Flow ........
In Situ Unsaturated Soil Water Budget
Soil Physical Measurements ..........
Clay Mineralogy .....................
Infiltration Rates . . ..............
Saturated Hydraulic Conductivity . . .
Solute Movement ....................
9
16
17
22
24
25
26
26
29
32
32
34
42
52
63
66
69
72
V
TABLE OF CONTENTS (CONTD)
Page
SUMMARY AND C O N C L U S I O N S .............. '.........................
LITERATURE C I T E D ................ .. . ...................... . .
97
101
APPENDICES...................................................... 105
I
LIST OF TABLES
Table
1.
2.
3.
4.
5;
6.
7.
8.
9.
10.
Page
Depths of neutron probe access tubes for
each treatment area at the Peabody Big
Sky M i n e ...................................
15
Methods used for chemical analyses of the
soil samples...................................
31
Actual soil water contents (W) compared to
calculated water contents (Wc) using the
unsaturated soil water flow model.............. ; . . .
36
Calculated annual soil water drainage from
a 150 cm profile for the four treatment
areas, Peabody Big ,Sky Mine............
40
Annual soil water balance for the 150 cm
profile of the four treatments, Peabody Big
Sky Mine, for the 1975 hydrologic y e a r ................
45
Annual soil water balance for deep profiles of
the four treatments, Peabody Big Sky Mine,
for the 1975 hydrologic y e a r ..........................
48
Bulk density, particle density and modulus of
rupture analyses of surface soil samples, ,
Peabody Big Sky Mine, November, 1974 ..................
53
Bulk density through depth of the four treatment
areas, Peabody Big Sky Mine, June, 1975.......... ..
57
Particle size distribution through depth for
the four treatment areas, Peabody Big Sky Mine,
November, 1974 ..................................
59
Particle size distribution and clay mineralogy
of representative soil samples from the four
treatments, Peabody Big Sky Mine, August, 1975 . . . . ;
65
LIST OF FIGURES
Figure
1.
Page
Experimental plot design of the study area
at the Peabody Big Sky M i n e ............................
10
Topsoiled nonvegetated spoils site,
Peabody Big Sky Mine .......................; .........
11
Topsoiled revegetated spoils site, Peabody
Big Sky M i n e ..........................................
11
Nontopsoiled revegetated spoils site,
Peabody Big Sky M i n e ..........
12
5.
Native range site, Peabody Big Sky Mine . . . . . . . . . .
13
6.
Drill rig used for tube installation and
taking of core samples, Peabody Big
Sky M i n e ..............................................
14
Example of dike used for flooding of
plots, Peabody Big Sky Mine .............
18
8.
Flooding of the plots, Peabody Big Sky M i n e ..............
19
9.
Plot after the flooding period. Neutron
probe is shown in operation, Peabody Big
Sky Mine ..........................................
20
Infiltration apparatus in operation showing
the collection of runoff, Peabody Big Sky
M i n e ..................................................
27
Diagram of sample holder used for conductivity
measurements, Peabody BigSky Mine .....................
28
Neutron probe field calibration curve,
Peabody Big Sky Mine
...........................
33
Soil desorption curves of 0-15 cm soil samples
from the four treatment areas, Peabody Big
Sky M i n e ....................
62
2.
3.
4.
7.
10.
11..
12.
13.
viii
LIST OF FIGURES (CONTD)
Figure
14.
15.
16.
17.
18.
19.
20.
21.
22
23.
24.
Page
Infiltration rates of the four treatment
areas, Peabody Big Sky M i n e ..........................
67
Saturated hydraulic conductivity through
depth for disturbed samples from the four
treatment areas, Peabody Big Sky Mine ................
71
Soil profile distribution of NO^-N from
November, 1974 to October, 1975, Peabody
Big Sky M i n e ..........................................
74
Soil profile distribution of NH.-N from June
to October, 1975, Peabody Big Sky M i n e ................
77
Soil profile distribution of PO.-P from
November, 1974-October, 1975, Peabody Big
Sky M i n e ..............................................
78
Soil profile distribution of NH.OAc extractable
calcium from November, 1974 to October, 1975,
Peabody Big Sky M i n e .................................
80
Soil profile distribution of NH.OAc extractable
magnesium from November, 1974 to October, 1975,
Peabody Big Sky Mine .................................
81
Soil profile distribution of NH^OAc extractable
potassium from November, 1974 to October, 1975,
Peabody Big Sky M i n e ..................................
83
Soil profile distribution of NH.OAc extractable
sodium from November, 1974 to October, 1975,
Peabody Big Sky Mine ...................................
84
Soil profile distribution of water soluble
calcium from June to October, 1975, Peabody
Big Sky M i n e ..........................................
87
Soil profile distribution of water soluble
magnesium from June to October, 1975,
Peabody Big Sky M i n e ..................................... 89
ix
LIST OF FIGURES (CONTD)
Figure
25.
26.
27.
28.
Page
Soil profile distribution of water soluble
sodium from June to October, 1975,
Peabody. Big Sky M i n e ............................ . . .
90
Soil profile SAR levels from June to
October, 1975, Peabody Big Sky M i n e .......... ..
.'91
Soil profile distribution of salt from
November, 1974 to October, 1975,
Peabody Big Sky M i n e .......................... .. . . .
.93
Soil profile pH levels from November, 1974
to October, 1975, Peabody Big Sky Mine ................
95
LIST OF APPENDICES
Appendix Table
I.
2.
Page
Soil Conservation Service classification
and profile description of the Yaraac
soil series.................. ........... ..
.106
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep I, topsoiled
nonvegetated treatment, Peabody Big Sky
Mine, summer of 1975 . . . .......... .
109
3.
Results of linear regressions and cal­
culated values of water movement model
parameters a and b- for rep 2, topsoiled
nonvegetated treatment, Peabody Big Sky
Mine, summer of 1975 .......................... .110
4.
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep 3, topsoiled
nonvegetated treatment, Peabody Big Sky
Mine, summer of 1975 ............ ............. ill
5.
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep I, topsoiled
revegetated treatment, Peabody Big Sky
Mine, summer of 1975 ........................ .
112
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep 2, topsoiled
revegetated treatment, Peabody Big Sky
Mine, summer of 1975 .................. ..
.113
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep 3, topsoiled
revegetated treatment, Peabody Big Sky
' Mine, summer of 1975 .................. ..
114
6.
7.
xi
LIST OF APPENDICES (CONTD)
Appendix Table
8.
9.
.10.
11.
12.
13.
14.
Page
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep I, nontopsoiled
revegetated treatment, Peabody Big Sky
Mine, summer of 1975 ....................
115
Results of linear regressions and cal­
culated values of water movement.model
parameters a and & for rep 2, nontopsoiled
revegetated treatment, Peabody Big Sky
Mine, summer of 1975 ....................
116
Results of linear regressions and cal­
culated values of water movement model
parameters o. and & for rep 3, nontopsoiled
revegetated treatment, Peabody Big Sky
Mine, summer of 1975 .......... ..
117
Results of linear regressions and cal­
culated values of water movement model
parameters # and & for rep I, native
range treatment, Peabody Big Sky Mine,
summer of 1975 . . ......................
118
Results of linear regressions and cal­
culated values of water movement model
parameters cl and b for rep 2, native
range treatment, Peabody Big Sky Mine,
summer of 1975 . . . .......... ■ ........
119
Results of linear regressions and cal­
culated values of water movement model
parameters a and b for rep 3, native
range treatment, Peabody Big Sky Mine,
summer of 1975,...................... .. .
120
Monthly soil profile water balance to the
150 and 480 cm depths for rep I, topsoiled
nonvegetated treatment, Peabody Big Sky
Mine, January, 1975 to April, 1976 . . . .
'121
xii
LIST OF APPENDICES (CONTD)
Appendix Table
15.
16.
17.
18.
19.
20.
21.
22.
Page
Monthly soil profile water balance to the
150 and 420 cm depths for rep 2, topsoiled
nonvegetated treatment, Peabody Big Sky
Mine, January, 1975 to April, 1976
122
Monthly soil profile water balance to the
150 and 450 cm depths for rep 3, topsoiled 1
nonvegetated treatment, Peabody Big Sky
Mine, January, 1975 to April, 1976 . ..........
123
Monthly soil profile water balance to the
150 and 450 cm depths for rep I, topsoiled
revegetated treatment, Peabody Big Sky
Mine, January, 1975 to April, 1976 . . . . . . .
124
Monthly soil profile water balance to the
150 and 480 cm depths for rep 2, topsoiled
revegetated treatment, Peabody Big. Sky .
Mine, January, 1975 to April, 1976 ............
125
Monthly soil profile water balance to the
150 and 330 cm depths for rep 3, topsoiled
revegetated treatment, Peabody Big Sky
Mine, January, 1975 to April, 1976 . . . . . . .
.126
Monthly soil profile water balance to the
150 and 300 cm depths for rep I, nontopsoiled revegetated treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976 . . . . ' .
127
Monthly soil profile water balance to the
150 and 480 cm depths for rep 2, nontbpsoiled revegetated treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976 ........
-
Monthly soil profile water balance to the
150 and 480 cm depths for rep 3, nontopsoiled revegetated treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976 ........
.129
.
1-28
xiii
LIST OF APPENDICES (CONTD)
Appendix Table
23.
24.
25.
Page
Monthly soil profile water balance to the
150 cm depth for rep I, native range
treatment, Peabody Big Sky Mine,
January, 1975 to April, 1976 . . . . . . . . . .
130
Monthly soil profile water balance to the
150 cm depth for rep 2, native range
treatment, Peabody Big Sky Mine,
January, 1975 to April, 1976 ............ .
,131
Monthly soil profile water balance to the
150 cm depth for rep 3, native range
treatment, Peabody Big Sky Mine,
January, 1975 to April, 1976 .......... .. . . .
132
ABSTRACT
A study was initiated in November, 1974 at the Peabody Big Sky
Mine near Colstrip, Montana to determine soil water and solute movement
in strip mine spoils. Three spoils treatments, consisting of topsoiled
nonvegetated, topsoiled revegetated and nontopsoiled revegetated spoils,
and a native range site were studied.
The testing arid evaluation of an unsaturated soil water movement
model showed the model to be applicable to soil water movement in both
the mine spoils and native range.
Calculation of in situ soil water budgets indicated drainage
was occurring from the spoils and native range. Both the water movement
model and the in situ water budgets indicated that the quantities of
soil water movement in the native range was approximately 1.5 times
greater than in the spoils.
The lower amount of soil water movement in the spoils was attri­
buted to bulk density, which was 54% higher than native range, and to
higher contents of silt and clay than native range. Clay mineralogy
analyses indicated that the dominant clay minerals in all treatments were
non-expanding lattice clays, which would not greatly limit soil water
movement due to expansion upon wetting.
Infiltration rates of the native range were 60-86% higher than
those of the spoils. These differences were attributed to the effects
of soil structure, vegetation and topsoiling techniques.
Saturated hydraulic conductivity of the native range was 3.5
times greater than that of the spoils treatments. The higher hydraulic
conductivity of the native range was attributed to textural differences
between the native range and spoils treatments.
No definite trends in solute movement were shown due to the
short time span of this study. With the exception of potassium and
NCL-N, the solute concentrations of the spoils were not, in general,
different from the native range. The spoils contained lower potassium and
higher NO3-N concentrations than present in the native range. Exchange­
able sodium percentages (ESP) and sodium adsorption ratio (SAR) indi­
cated no sodium problems were present in the spoils and native range.
The higher quantities of soil water movement in the native
range compared to the spoils indicate that greater amounts of
solute movement into the groundwater may occur from the native range
than from the spoils.
INTRODUCTION
An area of major concern with respect to surface strip mining of
coal in the Western United States is the effect of mining on soil water
and solute movement.
This study was initiated in order to determine soil
water and solute movement characteristics in strip mine spoils. Three
different spoil treatments and a native range site were compared. The
spoil treatments represented a range of geologic material and reclama­
tion techniques.
Water and solute movement characteristics obtained
from these spoils treatments should be representative of spoils mater­
ial present in the area surrounding Colstrip, Montana.
A study of native range was necessary in order to obtain informa­
tion regarding soil water and solute movement characteristics in land
undisturbed by mining activities.
Results obtained from the native
range site served as a basis of comparison for information obtained
from the spoil areas.
The native range site was chosen to be as
representative as possible of mineable rangeland in the Colstrip area.
The objectives of this study were to:
1)
2)
3)
4)
test and evaluate an unsaturated soil water move­
ment model and apply the model to the mine spoils
and native range;
determine the in situ water budget in spoils and
native range in order to determine quantities and rates
of soil water movement on a hydrologic year basis.;
measure'various physical characteristics in spoils
and adjacent native range soils in order to explain
differences in water movement which existed and to
determine the effects of mining on these physical
characteristics; and
determine solute concentrations and translocation
occuring in spoils and native range soils.
.
2
This study was conducted at the Peabody Big Sky Mine near Colstrip, Montana.
LITERATURE REVIEW
Coalfields in 8 western states - Montana, Wyoming, North
Dakota, South Dakota, Utah, Colorado, New Mexico and Arizona -
.
underlie in excess of 100 million acres and contain more than two
trillion tons of coal.
The coal deposits in Montana alone contain
13% of the total reserve in the United States (National Academy of
Sciences, 1974).
The area underlain by coal bearing rocks in Mon­
tana is 51,300 square miles which is 35% of the total area of the
state.
The projected area of land in Montana that will be disturbed
by surface coal mining by the year 2000 is in excess of 42,000
acres (Copeland and Packer, 1972).
It is important that sound re­
clamation techniques be established for these areas and that a
thorough knowledge of the effects of mining on both the disturbed
areas and surrounding areas is obtained.
. Thus far, the major portion of reclamation research has been
concerned with revegetation of strip mined areas.
Emphasis has not
been on the effects of mining on soil properties such as soil water
and solute movement.
Information on these factors is important
since any changes in soil water and solute movement could result in
■changes in the overall hydrologic system and groundwater quality of
the area.
Verma and Thames (1975) have done some preliminary work on soil
moisture in strip mine spoils in Arizona.
Using a neutron probe, it
was shown that partial recharge of the soil water occurred during.the
4
snowmelt period.
However, soil moisture remained near the permanent
wilting point to a depth of 200 cm during most of the period from
September through May.
No statements were made as to the occurrence
or amount of drainage from the spoils.
Sindelar, et al (1973) conducted a study which involved the
effects of three different spoils surface manipulation treatments on
soil moisture and revegetation at the Rosebud mine near Colstrip,
Montana.
Using soil moisture blocks, it was shown that the soil water
potential at the surface remained near 15 atmospheres from May through
November for all treatments.
At 30 and 60 cm depths, soil water poten­
tial remained above 15 atmospheres for most of the period while the
soil water potential remained significantly above 15 atmospheres for
the entire period at a depth of 120 cm.
The difference between these
results and those of Verma and Thames was probably due to Montana's
higher annual precipitation and lower mean annual temperature.
Also,
the surface manipulation treatments used tend to retain surface runoff
allowing the water to enter the soil.
. In stripping operations, the overburden is usually deposited in
long, roughly parallel ridges or banks.
These banks are then graded
or leveled by moving the tops of the ridges into the valleys result­
ing in near level or rolling topography.
Curtis (1973) measured moisture and density relations of graded
strip mine spoils in Kentucky.
The. study area was divided into four
5
blocks running parallel to former ridges which had been leveled.
Two of the blocks were scarified by traversing the plots with a
road grader equipped with ripper teeth.
His results showed approx­
imately 20% higher bulk densities at the 30 to 270 cm depths in
the leveled
ridges as compared to the spoils material which had
been moved into the valleys.
The moisture contents (g/g) were sig­
nificantly higher in the valleys than in the leveled ridges.
was assumed that the ridges became compacted in two ways.
It
First*
the weight of the stacked spoils resulted in compaction and second,
the heavy equipment, used in the grading operations resulted in com­
paction of the spoils.
It was also found that scarification had
little effect in reducing the surface density.
Over the winter,
however, all four plots showed a significant decrease in surface
density which was attributed to frost action during the winter.
Thus,
in areas where frost action is encountered, such as Montana, sig­
nificant reductions in surface densities could occur.
Limstrom (1960) did a study on strip mine spoils in Ohio.
The
infiltration rates on ungraded spoils banks and on adjacent graded
banks were determined.
The ungraded banks had infiltration rates of
10 cm/hr as compared to 1.5 cm/hr on the graded banks.
Evidently __
the resurfacing of mine spoils can result in compaction and affect
water movement in these spoils.
Resistance to compaction is determined by particle size distribu­
6
tion and composition of the particles in a soil.
Compaction is most
easily achieved with soils consisting of different particle sizes
where smaller particles can be forced into voids between larger parti­
cles (Warkentin, 1971).
This results in a decrease in pore volume
and therefore a higher bulk density.
The clay fraction of soils is generally considered as being the
particle size class which is the major limiting factor to water move­
ment.
However, the silt fraction can also have a great effect on soil
water movement.
and permeability.
Diebold (1954) related silt content to bulk density
He studied 215 medium textured soils in the south-
western United States.
It was found that soils with greater than 40%
silt had higher.bulk densities than the soils with less than this
amount of silt.
For all soils, the permeability decreased with in­
creasing bulk density.
For soils with the same bulk density, the per­
meabilities for soils with less than 40% silt were several times high­
er than those for the soils with higher silt contents.
Also, for soils
with low bulk densities (non-compacted), the infiltration rates were
1.5 times greater for soils with less than 40% silt.
At bulk densities
approaching 1.5 g/cm , the infiltration rates were twice as high for
the lower silt content soils.
Diebold speculated that the silt acts
as a clogging material resulting in lower permeability and infiltration
rates.
Upon compaction, at least three changes in porosity will occur:
7
(I) the total porosity is reduced;
volume of small pores increase; and
(2) the total number and relative
(3) the total number and relative
volume of larger pores decreases (Hill and Sumner, 1967).
Due to
these changes in porosity, water transmission in compacted soils is
greatly affected.
The volume of water flowing through a tube or pore
per unit of time is proportional to the fourth power of the. radius.
Halving the size of the tube decreases volume of flow by a factor of
16.
Therefore, decreasing the large voids through compaction has a
large effect in decreasing water transmission in saturated soils.
It
has been found that the logarithm of the saturated hydraulic conductiv­
ity decreases linearly as void ratio increases (Warkentin, 1971).
The relationship between porosity and unsaturated hydraulic con- '
ductivity is less straightforward.
The large voids are filled with
air and do not contribute to water flow, so there is less decrease in
conductivity with decreasing porosity.
Jackson (1963) studied the effects of soil texture and compaction
on unsaturated hydraulic conductivity: He found that the hydraulic
conductivity decreased with increasing compaction for a soil with high
clay content but the hydraulic conductivity changed little with com­
paction for a coarse grained soil.
Waldron, et al. (1970) examined the effect of compaction on the
unsaturated hydraulic conductivity of a Yolo loam.
The hydraulic
conductivities were determined under isotropic confining pressures of
8
2
0.1 to 3.2 Kg/cm .
For a decrease in porosity of 0.52 to 0.40 the
hydraulic conductivity decreased from 2xl0-^ cm/sec to I .5x10~^ cm/
sec.
This decrease in porosity is equivalent to an increase in bulk
density of 1.33 to 1.60 g/crn^.
Gumbs and Warkentin (1972) worked with a swelling clay soil
packed into columns.
It was found that small increases in bulk den-
3
sity over the range of 1.10 to 1.25 g/cm
markedly decreased the rate
of unsaturated water flow in the sample.
The preceding discussion of the effects of compaction on water
movement was limited to soils since no information could be located on
water movement in mine spoils.
However, the effects of compaction
which were discussed would affect mine spoils in the same manner.
More extensive research is needed in the area of soil water and
solute movement in mine spoils.
This information is needed not only
to determine reclamation procedures and future use of the mine spoils
but also to determine the effects of strip mining on surrounding areas
Any changes in soil water and solute movement characteristics could
conceivably affect the water supplies of nearby homesites and the qual
ity of existing range and cropland near the mining areas.
METHODS AND MATERIALS
Site Description and Design
The study area was located on the Peabody Big Sky Mine in south­
eastern Montana.
The four treatments were topsoiled nonvegetated
spoils, topsoiled revegetated spoils, nontopsoiled revegetated spoils
and native range.
The treatment plots all had approximately the same
slope and aspect.
Each treatment contained three replications measur­
ing 10x10 meters for a total size of 10x30 meters for each treatment.
The field site and design is shown in Figure I.
The topsoiled nonvegetated site was mined in February, 1974.
site was reshaped and topsoiled during the spring of 1974.
The
The site is
shown in Figure 2.
The topsoiled revegetated site was mined in October, 1970 and re­
shaped and topsoiled in the winter of 1972.
This site was seeded the
following spring at 25 Ibs/acre to a mixture of crested wheatgrass, in­
termediate wheatgrass, western wheatgrass, smooth brome, alfalfa,
yellow sweetclover, white sweetclover and green needlegrass.
The top^
soiled revegetated spoils site is shown in Figure 3.
Mining activity began on the nontopsoiled revegetated site in
September, 1970.
This site was recontoured several times, the last of
which was in the winter of 1974.
The site was seeded the following
spring to the same mixture and rate as for the topsoiled revegetated
spoils area.
The resulting stand of vegetation for this site was poor.
The nontopsoiled revegetated site is shown in Figure 4.
10
Figure I.
Experimental plot design of the studyarea at the Peabody Big Sky Mine.
11
Figure 2.
Topsoiled nonvegetated spoils site, Peabody Big Sky Mine
Figure 3.
Topsoiled revegetated spoils site, Peabody Big Sky Mine
12
Figure 4.
Nontopsoiled revegetation spoils site, Peabody Big Sky Mine
The soil of the native range site is in the Yamac soil series
which consists of deep, well drained soils formed in an alluvium from
sedimentary uplands.
Camborthids.
The soil family is fine-loamy, mixed Borollic
The Soil Conservation Service classification and profile
description of the Yamac series is given in Appendix Table I.
The
native range site is shown in Figure 5.
Neutron probe access tubes were installed in the center of each
rep in November of 1974.
A trailer drawn Giddings^ drill rig was used
to prepare holes to receive the tubing.
The drill rig is shown in
■'‘Mention of trade names does not imply endorsement, but its purpose
is to inform the reader.
13
In Figure 6.
The tubes were installed as deep as possible before
encountering resistance too great for the drill rig.
The corresponding
tube depths are listed by replication in Table I.
Figure 5.
Native range site, Peabody Big Sky Mine
14
Figure 6.
Drill rig used for tube installation and
and taking of core samples
15
Table I.
Depths of neutron probe access tubes for each treatment
• area at the Peabody Big Sky Mine,
Treatment
Replication
Tube Depth (cm)
Topsoiled nonvegetated
spoils
I
2
3
480
420
450
Topsoiled revegetated
spoils
I
2
3
450
480
330
Nontopsoiled revegetated
spoils
I
2
3
300
480
480 .
Native range
I
2
3
180
180
180
16
Neutron Probe Calibration
Since a major portion of the study involved the use of
neutron probe, it was necessary to determine whether or not the
factory calibration was valid for the soils of the study area.
Core samples were taken from each treatment area in 30 cm incre­
ments and weighed immediately.
Neutron probe access tubes were
installed following the taking of the core samples and moisture
readings were taken using the neutron probe.
The samples were oven-
dried at IlO0C and the oven-dried weight of each core sample was
determined.
Using the moist weights from the field and the corre­
sponding oven-dried weights, the gravimetric water content of each
sample was calculated.
The volume of each sample was determined
I
from the inside diameter of the cutting tip and the core length
of 30 cm.
The bulk density of each sample was calculated using
Equation I.
oven dry weight of sample (g)
Bulk density
q
volume of sample (cm)
(I)
The percent moisture by volume of each sample was then calcula­
ted using Equation 2.
17
Water content,
L
.
.
water content, % by weight
by volume = —
bulk density
(2)
Linear regression analysis was run on the neutron probe read­
ings, expressed as count ratio vs percent moisture by volume.
A
calibration curve was then calculated using the results of the lin­
ear regression.
The field calibration was compared to the factory
calibration to determine if any significant differences were present,
Unsaturated Soil Water Flow
In order to obtain knowledge of the unsaturated flow character­
istics of the treatment areas, a mathematical model developed by
Sisson (1972) which describes the water flux through the soil was
utilized during the summer of 1975.
in order to apply the model.
water movement can be present.
Two requirements must be met
First, no layers restricting soil
Secondly, a uniform matric potential
(Tm) must be present to the depth the calculations are made.
The
model has been tested on various agricultural soils in Montana but
has not been applied to mine spoils.
It was felt that spoils meet
the first requirement since any layers restricting soil water move­
ment would have been destroyed by mining activity.
The model utilizes Equation 3,
(3)
18
where
w = total water In cm above depth x
x = depth in cm to which Ym is constant
t = time in days from occurrence of soil water recharge
a and b are constants
In order to calculate the values for the constants the follow­
ing procedures were used.
I.
Dikes measuring 3x3 meters were constructed on each rep
with the neutron probe access tube being located in the
center of the dike.
An example of this is shown in Fig­
ure 7.
Figure 7.
Example of dike used for flooding of plots
19
2.
The plots were then flooded with the head being maintained
by subsequent additions of water.
Ponding was maintained
for a period of approximately 36 hours.
ation is shown in Figure 8,
The flooding oper­
A sample of the ponding water
was analyzed for pH, electrical conductivity, calcium,
magnesium, sodium, sodium adsorption ratio (SAR), carbonates
and bicarbonates in order to determine whether or not solutes
were present which might affect water movement through the
soil.
Figure 8.
Flooding of the plots
20
3,
After completion of the ponding period, the remaining
water was released and the plots covered with plastic to
prevent moisture loss through evaporation.
Moisture
readings were then taken at 30 cm increments with the
neutron probe. These readings were considered as being
at time = 0.
Figure 9 shows a plot after the flooding
period.
Figure 9.
4.
Plot after the flooding period.
shown in operation
Neutron probe is
Thereafter, moisture readings were taken onxan hourly basis
the first day and with decreasing frequency the following
days as the soil water flux decreased,
The total time
21
period during which readings were taken covered 30 to 90
days.
A series of water contents at various depths through
time were thus obtained.
Using Equation 3, and letting
R = ax^"1"^
(4)
the following equation is obtained.
W = Rt"b
(5)
Taking the natural logarithms of both sides of Equation 5
yields
In w = In R - b In t
(6)
Equation 6 is in the form of a linear equation where In w and
In t are the y and x variables, respectively, and -b is the slope.
Using the water contents (w) obtained at various times (t), lin­
ear regressions were performed in order to determine the slope.
linear regression was run for each depth.
The resulting r
2
A
values
for these regressions were then used to determine the maximum depth
to which a uniform i(jm was obtained.
Since the model should hold true
o
for the region of uniform
(Jjii1,
we used the r
values as an indicator
of the goodness of fit of the data to the model.
Following this
22
■reasoning, the r
values should show an abrupt and continued decrease
at depths below which a nearly uniform
was obtained.
In this
manner, the value Of x in each plot was determined,
Equation 7 is the equation of the regression line
In w!* = s In t^ + I
(7)
where
s = slope of regression line
I = intercept of regression line .
By comparing Equation 7 with Equation 6, it is seen that b is
the negative of the slope of the regression line.
By use of Equation 7 and any value of t^, the value of w. which
lies on the regression line at that time can be calculated.
The only
unknown value is a which can now be solved for by substitution of the
known values into Equation 3,
In s i t u
Unsaturated Soil Water Budget
Using the neutron probe, soil moisture readings were taken on
each rep on a monthly basis from January, 1975 to May, 1976.
moisture readings were incorporated into a water budget model.
tion 8 is the,water budget equation which was used.
These
Equa­
23
+ ASWC =’PPT - ET* + W F - R O
(8)
where
ASWC = change in soil water content
PPT = precipitation
ET = evapotranspiration
WF = water flow by unsaturated or saturated processes
into or out of the zone
RO = runoff
The signs associated with Equation 8 indicate the direction of
water movement from the system.
A negative value signifies a loss of
water from the system while a positive value indicates a gain in water.
Of the five hydrologic components in Equation 8, ASWC., PPT, ET
and RO are either measured or estimated.
WF is found by rearranging
Equation 8 to give
WF = ASWC - PPT + ET + RO
Once WF is estimated, all flow components are available for the
water balance.
ASWC was obtained from the monthly neutron probe read­
*
Evapotranspiration (ET) results in a loss of water from the
profile.
For purposes of clarification, all ET values-presented in the
results will be designated as negative values.
However, in order to
utilize Equation 8, the aboslute value of the negative'ET must be used,
i.e ., + ASWC = PPT - {ET}
- RO + W F , where ET is a negative value.
24
ings.
PFT was estimated from rainfall gauge stations located at the
Western Energy Rosebud Mine, 5 miles northeast of the field site, and at
the Peabody Big Sky Mine.
ET was obtained from lysimeters located
on mine spoils at the Western Energy Rosebud Mine.
RO was estimated
as being zero since the slopes of all the treatment areas are nearly
level.
The RO component is subject to the most error by making this
estimation but no means of measuring runoff were available,
.
Soil Physical Measurements
Surface soil samples from each rep were analyzed for particle
density, bulk density and modulus of rupture,
were also constructed.
Soil desorption curves
The soil samples used for the particle den­
sity, modulus of rupture and soil desorption curve determinations
were taken in November, 1974 while the samples for bulk density were
taken in February, 1975,
Procedures for particle density, modulus
of rupture and soil desorption curves were as outlined by the United
States Salinity Laboratory (1969).
Bulk densities were measured
using the ped method described by Blake (1965),
In addition, bulk densities through depth were determined in
June of 1975.
rep.
Soil cores were taken in 30 cm increments from each
The samples were then ovendried at IlO0C and weighed.
The
volume of the cores were calculated from the inside diameters' of. the
cutting tip and the core length of 30 cm.
then calculated using Equation I,
The bulk densities were
25
Since a layer of sandstone bedrock is present at a depth of 180
to 210 cm on the native range site, it was not possible to obtain
core samples beyond this depth using our drill rig.
Therefore, a
core sample was obtained in June, 1975 from the native range site by
a larger drilling rig operated by the Peabody Coal Company. The
core extended to a depth of 6 meters, Where the cores were intact,
the bulk density was determined using Equation I,
In this case,
the core volume was determined directly using calipers.
Bulk den­
sity was obtained using.the ped method when the cores were not in­
tact.
At some depths, no useable peds were obtained,
No values of
bulk density were determined at these depths.
Particle size distribution was determined on core samples from
each rep.
The samples were taken in November, 1974,
The 6 meter
native range core sample taken in June? 1975 was also analyzed for
particle size.
The analyses were performed using the hydrometer
method described by Day (1965).
Particle size analyses were done
by the Peabody Coal Company Central Laboratory in Freeburg, Illinois.
Clay Mineralogy
Clay mineralogy analyses were done on representative surface
samples from each treatment. The analyses were performed using xray diffraction techniques under the supervision of Dr, Murray Klages,
Professor of Clay Minerology, Montana State University.
26
Infiltration Rates
Infiltration rate measurements were performed on each rep.
The infiltration rates were determined using the method and appar­
atus described by Meeuwig (1971).
shown in Figure 10.
The infiltrometer apparatus is
Basically, the device consists of a plexiglas
water reservoir which delivers a raindrop effect onto the soil sur­
face through 517 capillary tubes.
A
flowmeter registers the water
application rate while soil surface runoff is funneled into a collection cup.
The infiltrometer encompasses a .31 m
o
sample area.
Simulated rainfall was applied at a rate of 16.3 cm/hr.
The volume
of runoff was measured every 3 minutes for a 30 minute test period.
The high rate of wa,ter application simulated a severe rainstorm in
volume but not in raindrop collision force.
Saturated Hydraulic Conductivity
Saturated hydraulic conductivities with depth were determined
on disturbed samples from each treatment.
The constant head per-
meameter used was similar to that described by Klute (1965) . The
sample holders were constructed from 10 cm lengths of PVC pipe
having an inside diameter of 7.62 cm.
The bottoms of the holders
were sealed with plexiglas through which a 0.64 cm drainage hole
had been drilled.
holder,
A funnel was then attached to the bottom of each
A diagram of the sample holder is shown in Figure 11,
27
Figure 10.
Infiltration apparatus in operation showing the collection
of runoff.
A device was set up so as to maintain a constant head above each
soil sample.
A 0.005
CaClg solution was used in order to maintain
the salt content of the samples.
It was felt that the use of dis­
tilled water would result in the removal of soluble salts from the
sample.
If this occurred, flow could be decreased due to soil dis­
persion resulting in lower hydraulic conductivity values.
28
7.62 cm I.D.
water level
10 cm
soil
sample
Figure 11.
Diagram of sample holder used for conductivity measure­
ments .
The soil samples were air dried and ground to pass a 2 mm sieve.
Filter paper was placed in the bottom of each sample holder to pre­
vent loss of the sample and the funnels were stoppered.
Approximately
3
230 cm
of soil were placed in each holder and packed with a vibrator.
29
The holders were then filled with the C a C ^ solution taking care
not to disturb the samples.
The constant head devices were then
set up and the samples allowed to saturate for 16 hours,
The
stoppers were removed and the volume of flow measured until flow
from the sample was constant.
Once the equilibrium flow condi­
tions were obtained, which required 7 to 14 days, the saturated
hydraulic conductivities were calculated using the following form
of Darcy's Law.
• K = (Q/At) (L/AH)
(9)
where
K = conductivity of the soil to water in cm/day
Q = volume of flow in cm
3
at equilibrium
A = cross sectional area of sample in cm
2
t = time in days
L = length of sample in cm
AH = hydraulic head in cm
Solute Movement
In order to obtain measurements on solute movement,■core samples
were taken on a twice yearly basis from each rep,
in November, 1974 and June and October of 1975,
Samples were taken
These samples were
taken to the maximum depth possible using our drilling rig.
In addi­
tion, a 6 meter core sample from the native range site was taken in
30
June, 1975 by a larger drilling rig operated by Peabody Coal Com­
pany.
All samples were analyzed for NO^-nitrogen, PO^-phosphorus,
exchangeable calcium-magnesium-sodium-potassium, pH and electrical
conductivity.
In addition to these analyses, the samples taken
in June and October of 1975 were analyzed for NH^-nitro'gen and
water soluble calcium-magnesium-sodium for calculation of sodium
adsorption ratio (SAR).
for each analysis.
Table 2 lists the methods and references
All chemical analyses were done by the Peabody
Coal Company Central Laboratory in Freeburg, Illinois.
31
Table 2.
Methods used for chemical analysis of the soil samples.
Method
Analysis
Reference
NO3-N
Phenoldisulfonic acid
method
Bremner (1965a)
NH7-N
4
Steam distillation method
Bremner (1965b)
PO4-P
NaHCO3 extractable P
Olsen (1954)
1:20 soil:l N NH4OAC
extract analyzed by atomic
adsorption spectrophotometry
Pratt (.1965)
Saturated paste extracts
analyzed by atomic
adsorption spectrophotometry
U 1S, Salinity
Lab (1954)
pH
1:2 soil:water
Peech (1965)
Electrical
conductivity
1:2 soil:water extract
U„S, Salinity
Lab (1954)
Exchangeable
Ca-Mg—Na-K
Water soluble
Ca-Mg-Na
tNa}
SAR
(({Ca} + {Mg})/2)1/2
•
...
where all concentrations
are in. meq/L
U .S Salinity
Lab (.1954)
RESULTS AND DISCUSSION
Neutron Probe Calibration
The field calibration curve for the neutron probe and the
factory calibration are shown in Figure 12.
Data for the field
calibration were obtained from observations of percent moisture
by volume vs. count ratio comparisons from profiles in each treat­
ment.
The data from the topsoiled nonvegetated site was consider­
ably different from the other three sites.
This difference could
possibly have been due to environmental factors affecting the neutron
probe equipment, equipment malfunction or an insufficient length
of time allowed for the scaler unit to warm up.
Although the exact
cause for the variation in data is not known, it was felt that the
topsoiled nonvegetated data was in error.
Calibration data from this
site were therefore deleted. By deleting the topsoiled nonvegetated
data, a high correlation of the data to the regression line was obtain'ed indicated by an r
2
of 0.81,
giving the equation for the field
calibration curve shown by Equation 10.
moisture (% by volume) = 14,27 (count ratio) + 7.31
(10)
Equation 11 is the factory calibration curve.
moisture (% by volume) = 45.79 (count ratio) - 4.83
(11)
The slope o f .14.27 for the field calibration was significantly
Factory calibration
Slope = 45.794 a
Intercept = -4.83
P 30
Field calibration
Slope= 14.27 h
Intercept=7.309
r2 =0 .8 0 9
Count Ratio
Figure 12.
Neutron probe field calibration curve, Peabody Big Sky Mine,
June, 1975. Slopes followed by the same letter indicates no
significance at the 0.01 level.
34
different at the 0.01 level
the factory calibration.
2
compared to the slope of 45.79 for
Use of the factory calibration would re­
sult in moisture content estimates substantially different from the actual
moisture contents.
Due to this and to the high calibration correl­
ation between volumetric moisture content and field neutron probe
counts, Equation 10 was used for the computation of all moisture
contents presented in this thesis.
At low count ratios, the field calibration would give erron­
eous moisture contents.
Theoretically, a count ratio of ,zero indi­
cates no moisture present.
However, the field calibration curve
would indicate 7.31% moisture by volume at a count ratio of zero.
Since very few of the count ratios obtained in the entire course of
the study were below 0.5 and none below 0.2, the problem associated
with count ratios near zero did not affect our calculations.
Unsaturated Soil Water Flow
Results of the linear regression of the natural logarithm of
total water content (w) vs. natural logarithm of time (t) and the
calculated values of the water movement model parameters a and b at
each depth for each rep are given in-Appendix Tables 2 through 13.
The depth (x) to which a uniform matric potential, 4y, was obtained
O
r
Throughout the remainder of this thesis, any reference to sig­
nificance will be at the 0.05 level unless otherwise stated.
r
35
is indicated in each table.
In some cases, the choice of x was arbi­
trary since there wasn't always an abrupt drop in the r^ values nor did
the r
9
values continue to decrease with depth in all cases.
values of a and b decreased with depth for all reps.
In general,
This indicates
that a and b are not true constants but are variable to a certain ex­
tent.
Also, the b parameters for the native range reps were generally
higher at any given depth than for the spoils treatments.. The greater
the value of b, the greater is the negative slope of the regression of
In w vs In t., Therefore, the larger b values for the native range reps
indicate a higher rate of soil water movement through the native range
soil as compared to. the spoils treatments.
The chemical analysis' of the water used for the flooding of the
plots were: pH (7.1), electrical conductivity (1300 ymhos/cm), calcium
(7.07 mg/1), magnesium (14.53 meq/1), sodium adsorption ratio (1.17),
carbonates (0 meq/1) and bicarbonates (7,08 meq/1). None of the concen­
trations are at levels which would result in decreased soil water move­
ment through their physio-chemical effect on the soil,
was of particular importance.
The SAR of 1.17
In general, use of irrigation water hav­
ing SAR values of 10 or greater results in dispersion of the clay frac­
tion of soils which could decrease soil water movement.
The SAR of the
flooding water was well below the critical value of 10.
A comparison of calculated and actual soil water contents is given
in Table 3.
The r
2
value given in Table 3 is the r
2
of the linear re- .
Table 3.
Actual total soil water contents (IV) compared to calculated water contents (IV ) using the
unsaturated soil water flow mo d e l .
Topsoiled
nonvegetated
I
Topsoiled
revegetated
Nontopsoiled
revegetated
Native range
r
Model Parameters
2
a
b
x (cm)
t (days)
IV^ (cm)
iV(cm)
Difference(cm)*
47.87
48.41
-0.54*
0.87
0.1969
0.0081
240
49.2
2
0.68
0.2094
0.0106
240
120.0
50.62
48.68
1.94*
3
0.71
0.2176
0.0047
210
63.1
45.96
44.71
1.25*
I
0.43
0.2355
0.0091
120
78.2
28.37
26.67
1.70*
2
0.73
0.2406
0.0078
180
78.3
43.59
42.78
0.81*
3
0.11
0.2292
0.0021
60
79.2
13.74
13.46
0.28*
I
0.58
0.2329
0.0058
60
49.1
13.99
13.03
0.96*
2
0.83
0.1968
0.0052
270
48.2
53.61
52.50
1.11*
3
0.53
0.2195
0.0230
60
102.2
13.01
13.03
-0.02*
I
0.91
0.2321
0.0143
90
64.0
20.99
20.36
0.63*
2
0.81
0.2329
0.0170
90
64.0
21.08
20.46
0.62*
3
0.90
0.2009
0.0274
150
50.0
31.06
30.23
0.83*
Mean
^
Difference(cm)'
O
rep
Ig
Treatment
0.93*
0.68b
0.69b
*
Difference within the same treatment followed by the same letter are not significant at the 0.05 level
t
Means followed by the same letter are not significant at the 0.05 level
37
gression for depth x indicated in Appendix Tables 2 through 13.
value of x is the depth to which a uniform
rep.
\pm
The
was obtained in each
The a and b values are those which correspond to x.
Neutron
probe readings were taken on October 7, 1975 which was after the water
movement model testing period was terminated.
The time t is the per- '
iod of time from t = 0 for each rep to the time of the October 7th
readings.
w c is the total water content above x calculated from the
model parameters shown,
w is the actual water content above x obtained
from the on-site October 7 neutron probe readings.
The differences ■
between w c and w are presented in the last column.
In general, the calculated values were higher than the actual
water contents.
However, the differences are small when compared to
the profile depth and time period from which w
was calculated. For
c•
example, the largest difference of 1.94 cm is for a 240 cm profile
over a period of 120 days.
The water movement model is applicable to
unsaturated soil water flow in the mine spoils since the differences
between w and w c within each treatment were non-significant.
Since
the three mine spoil treatments represent a range of geological mater­
ial and reyegetation management at the Peabody Big Sky Mine, it can be
assumed that the water movement model is applicable to all mine spoil
types present at the mine.
Further, it is felt this model should be
applicable to mine spoil studies in the Western region,
2
It should be noted that the r- of the regression•is not necessarily
38
an indicator of the accuracy of the model since the differences
between w^_ and w do not always increase with decreasing r
values.
The variation in the r^ values between reps could be due in part to
environmental factors affecting the neutron probe measurements.
It
is possible that the r^ values could be improved by increasing the
number of probe readings.
It appears that data which show a low
degree of correlation with the regression line still result in model
parameters which give good predictions of water content of the soil.
The annual drainage from a 150 cm. profile was calculated for
each rep using the water movement model with t = 365 days.
This
time interval was used so that the drainage could be expressed on a
hydrologic year basis.
reasons.
A profile depth of 150 cm was chosen for two
First, the average depth for all reps to which a uniform
was obtained was 150 cm.
It was felt that use of the model for
depths greater than 150 cm would not be valid for the reps which had
uniform ipm at depths less than 150 cm.
Second, 150 cm was assumed to
be the maximum rooting depth of any vegetation present.
Any water ■
draining past 150 cip would not be taken up by plants and it would not
be a serious error to assume that the water would continue in its
downward direction Of flow.
First, the drainages were calculated
using the a and b parameters calculated at the maximum depth of uni- .
form ipm .
However, since these parameters vary with depth and the
depth of uniform ipm varied between the reps within the same treatment,
39
the calculated drainages showed a wide variation within treatments.
The drainages were then calculated using the a and b parameters cal­
culated from the regression data for the 150 cm depth for each rep.
These data are shown in Table 4 .
PiZ^ is the initial water content
in a 150 cm profile and was obtained from the neutron probe data
at t = 0.
This initial water content would approximate the soil water
content after a recharge occurrence such as spring melt.
PiZf is
the final water content in the profile 365 days after the flooding
or recharge event calculated using the water movement model.
The
difference between PiZ^ and PiZ^ represents the drainage from the profile
for a one year period. The values of 0.05 and 7.25 cm for rep 3,
'
topsoiled revegetated and rep 3, native range, respectively, were
shown to be Outliersl at the 0.05 level.
The term outlier refers to
values which are significantly greater or less than the rest of the
data.
The values of 0.05 and 7.52 were not used in the calculation
of the drainage means for the two treatments.
No significant differences were present between the drainage
means for each treatment in Table 4.
However, these data indicate
the drainage to be approximately equal for the spoils treatment while
the native range drainage is approximately 1.5 times greater.
Annual
V
v
drainage from these spoils treatments ,on a hectare basis represents
approximately 250 m^ha-^ whereas the annual drainage from the native
range treatment would be 375 m^ha "K
Therefore, when the,total area
40
Table 4.
Calculated annual soil water drainage from a 150 cm profile
for the four treatment areas, Peabody Big Sky Mine.
ou.
Average
drainage (cm)
Treatment
rep
Topsoiled
nonvegetated
I
2
3
34.71
36.81
35.39
31.09
33.53
33.84
3.62
3.28
1.45
2.78*
Topsoiled
revegetated
I
2
3
36.56
37.18
33.54
34.59
35.04
33.49
1.97
' 2.14
■0.05*
2.05*
Nontopsoiled
revegetated
I
2
3
31.26
32.31
34.21
30.85
30.28
29.48
0.41
2.03
4.73
2.39*
Native range
I
2
3
36.07
36.10
36.90
32.40
32.58
29.58
. 3.67
3.52
7.52*
3.59*
*
Wf
drainage (cm)
determined to be outliers at 0.05 level and not included in average
drainage
means with same letter indicate no significant difference at the
•0.05 level
41
of the mine spoils present are taken into account, the drainage is
substantial.
It is also evident that the same area of native range
would result in considerably greater amounts of drainage.
These annual drainages were calculated on the assumption that
no further precipitation or evapotranspiration occurred after the
initial recharge.
Soil water drainage is exponential which means
that the rate of downward movement is greatest immediately after
recharge of the profile with the rate of movement decreasing through
time.
Thus, a large portion of the water would drain from the pro­
file before any substantial amounts were lost through evapotranspir­
ation.
The assumption that no evapotranspiration occurred during
the year does not greatly affect the calculated drainage values.
Any further precipitation occurring, minus losses through runoff and
evapotranspiration, would tend to increase the drainage values.
42
In s i t u
Unsaturated Soli Water Budget
Soil water budgets on a yearly basis for each rep were deter­
mined in order to obtain information on the characteristics and
quantities of soil water movement in the four treatments.
The
monthly soil water conditions were determined for the 150 cm pro­
file. depth and for the maximum profile depth of the neutron probe
access tube.
These monthly soil water data were used to determine
the water budget on a hydrological year basis for each rep.
These
monthly soil water data for the two profile depths of each rep dur­
ing the period of January, 1975 through April, 1976, are given
in Appendix Tables 14 through 25.
The evapotranspiration values
were obtained from weighing lysimeters installed in plots having a
one year growth of vegetation.
These plots are located on mine
spoils at the Western Energy Rosebud Mine at Colstrip, Montana.
No evapotranspiration values were available for the period of January
to May of 1975.
It was assumed that evapotranspiration for these
months were equal to evapotranspiration values for the same months
in 1976.
It was believed that this approach would not introduce
significant error into these calculations.
Therefore, the measured
i
evapotranspiration values for January through May of 1976 were used
for the unknown values in 1975.
As discussed in a previous section,
these plots were flooded in order to test and evaluate a soil water
movement model.
A two to three day flooding period was followed
by a one to three month period during which time these plots
43
were covered with polyethylene
(see methodology).
The amount
of water which entered the profile during flooding was calculated
by difference using neutron probe readings taken prior to and follow­
ing the flooding operation.
This increase in water content due to
flooding was considered as being nearly equivalent to precipitation
for the period when the plots were covered with plastic.
Therefore,
this quantity was entered under the PPT hydrologic factor for each
rep during the month during which flooding occurred.
are indicated in Appendix Tables 14 through 25.
These values
The quantity of
water which entered the profile during flooding is normal for a
monthly period and in some cases was less than would occur during a
wet month.
Therefore, flooding of these plots did not introduce
an abnormal flux of water into the system.
Changes in soil water content were not available for the first
rep of the topsoiled nonvegetated and nontopsoiled revegetated treatments
nor the third rep of the native range treatment from January to August,
1975.
The neutron probe access tubes in these reps were damaged and
the device for repairing the tubes was not available until early August.
When evapotranspiration, runoff and soil water parameters were
considered it was found that, in general, all reps showed a negative
value for soil water flow (WF) for the year of 1975 and for the total
period of January, 1975 to April, 19761
Since a negative value of WF
indicated drainage loss from the profile, it is evident that drainage
44
is occurring.
Most of the reps showed maximum drainage occurred
during the months of April and May which corresponds to the spring
melt period.
Using the data presented in Appendix Tables 14 through 25, the
annual water balance for a 150 cm profile for the 1975 hydrologic
year was calculated for each treatment.
A profile depth of 150 cm
was chosen so that a comparison could be made between in_situ..measure­
ments with the neutron probe and annual drainage from a 150 cm profile
calculated using the water movement model discussed in the previous
section.
The annual in situ soil water balance for the 150 cm profile
of each treatment is given in Table 5.
The amounts of water which
entered the profile during flooding and the period of time which the
plots were covered with plastic varied between treatments.
This
variation resulted in different values for precipitation and evapotranspiration between treatments shown in Table 5.
The values of WF
are all negative indicating drainage from the 150 cm profile occurred
from each treatment.
The native range showed the greatest drainage as
indicated by a WF value of -12.28 cm.
The topsoiled revegetated treat­
ment with a WF value of -11.07 cm had the greatest drainage for the
spoils treatments followed by a drainage of 7.75 cm from the topsoiled
nonvegetated treatment.
The drainage of 4,60 cm from the nontopsoiled
revegetated treatment was the lowest of the four treatments.
These drainages from the 150 cm profile shown by the water balance
45
Table 5.
Annual soil water balance for a 150 cm profile in the four
treatments, Peabody Big Sky Mine for the 1975 hydrologic
year. Negative values indicate loss of water from the
profile while positive values indicate gain of water. All
data are presented in centimeters.*
Hydrologic Components
PPT
ET
RO
WF
ASWC
38.01
. -23.51
0.0
Topsoiled
revegetated
37.47
-21.20
0.0
-11.07
5.20
Nontopsoiled
revegetated
41.24
-27.40
0.0
- 4.60
9.24
Native
range
44.54
-25.82
0.0
-12.28
6.44
*
Ln
Topsoiled
nonvegetated
I
Treatment
6.75
, PPT = precipitation
ET = evapotranspiration
RO' = runoff
WF = waterflow by unsaturated or saturated processes into or
out of the zone
ASWC = change in soil water content
(Table 5) are considerably greater and more variable between treatments
than the calculated annual drainage using the water movement model shown
in Table 4.
One source of this variation was the use of the same evapo­
transpiration values for all treatments.
Evapotranspiration would vary
46
considerably between treatments due to the presence of vegetation
on two of the treatments.
The greater amount of vegetation present
on the topsoiled revegetated and native range treatments as compared
to the sparse vegetation found on the weighing lysimeters would
result in higher evapotranspiration losses than were shown.
Once the
surface of the bare soil on the nontopsoiled revegetated and topsoiled
nonvegetated treatments dried, evapotranspiration would decrease due to
the impedance of water movement through the dry layer (Yang and Delong,
1971)
whereas the plants on the other two treatments would continue
to transpire water.
Thus, these greater evapotranspiration losses that
would occur on the topsoiled revegetated and native range treatments
would result in lower amounts of drainage than those values calculated
in Table 5.
These drainage values of the four treatments calculated
using the water budget would probably still be higher than those drainages from the 150 cm profile calculated with the water movement model.
The fact that no further precipitation was accounted for following the
initial recharge of the profile in the use of the water movement model
V
calcualtions probably accounts for the lower drainage values obtained
from the model.
The values for ASWC in Table 5 are positive for all treatments
indicating that the amount of water stored in the 150 cm profiles
showed a net increase during the year.
The nontopsoiled revegetated
treatment showed “the largest change in soil water content with a gain of
47
9.24 cm during the 1975 hydrologic year.
The topsoiled nonvegetated,
topsoiled revegetated and native range treatments showed approximately
the same increases in soil water content with values of 6.75, 5.20 and
6.44 cm, respectively.
It is therefore evident that substantial in­
creases in soil water content occurred in the 150 cm profiles during
1975 and that drainage.from the profiles occurred.
Using the data presented in Appendix Tables 14 through 22, the
annual water balance for the maximum depths of the neutron probe access
tubes on each of the three mine spoils treatments, which ranged from
390 to 435 cm, was calcualted,
The access tubes used in these calcula­
tions were the same as those used for calculation of the water balance
of the 150 cm profiles, A comparison of the in situ water balances for
these deep profiles to those of the 150 cm profiles was made so that any
changes in the water balance with depth could be determined.
The data
for the native range treatment was not included in these calculations
since the maximum depth of the access tubes in the native range treat­
ment was only 180 cm.
The water balance for the 1975 hydrologic year for the deep pro-'
files of the three mine spoils treatments is presented in Table 6.
The
profile depths shown in the table are the average depth of the three
replicated neutron probe access tubes located in each treatment.
The
amount of drainage from the deep profile showed a decrease for all
treatments compared to the 150 cm profile drainage (Table 5).
For
48
example, drainage from the topsoiled revegetated treatment for a 420
cm profile was 9.93 cm as compared to 11.07 cm for the same 150 cm
profile, and drainage from the topsoiled nonvegetated treatment was
Table 6.
Annual soil water balance for deep profiles of the four
treatments, Peabody Big Sky Mine for the 1975 hydrologic
year. Negative values indicate a loss'of water from the
profile while positive values indicate a gain in water.
All data are presented in centimeters.
Hydrologic Components
Profile
Depth (cm)
PPT
ET
. 435
38.01
'-23,51
0.0
-1.92
12,58
Topsoiled
revegetated
420
37.47
-21.20
0.0
-r9.93
6.34
Nontopsoiled
revegetated
390
41.24
-27.40
0,0
.1,17
15.01
Treatment
Topsoiled
nonvegetated
PPT
ET
RO
WF
RO
WF
ASWC
=
=
=
=
precipitation
evapotranspiration
runoff
waterflow by unsaturated or saturated processes into or out of
the zone
ASWC = change in soil water content
Each component is an average of 2 reps with the exception of the topsoiled revegetated treatment components which are an average of 3 reps.
1.92 cm compared to 7.75 for the same 150 cm profile.
As discussed
previously, the vegetation on the topsoiled nonvegetated treatment would
result in a lower amount of drainage than is shown in Table 6.
In the
49
case of the nontopsoiled revegetated treatment, the positive WF value
indicates that no drainage occurred but instead upward movement of
1.17 cm of water into the profile occurred. This upward movement
could be due to the presence of higher quantities of water below the
390 cm depth.
This higher amount of water at lower depths would
result in upward movement of water due to the presence of a water move­
ment gradient towards the surface.
The decreasing amount of drainage from the deep profile as com­
pared to the 150 cm profile indicated that a portion of the water which
drained from the 150 cm profile was stored at.lower depths rather than
all of it continuing its downward movement.
This is shown by a com­
parison of the differences in ASWC in the 150 cm and deep profiles
of each treatment with the amounts of drainage from the 150 cm profile.
This comparison indicates that of the water draining out of the 150 cm
profile, 10, 75 and 100% was stored at lower profile depths in the topsoiled, revegetated, topsoiled nonvegetated and nontopsoiled revegetated
spoils treatments, respectively.
The topsoiled revegetated treatment
stored the least amount with 90% of the water draining from the 150 cm
profile continuing its downward direction of flow.
We are considering only one-dimensional unsaturated flow, that
being in the vertical direction.
Three possible situations can exist
with respect to the verticle unsaturated soil water movement.
These
are: I) water can flow in a net upward direction towards the surface
50
with the rate of flow increasing or decreasing over time,
ibrium conditions' can establish or
2) equil­
3) net downward flow from the
surface towards the groundwater table can occur with the rates of flow
either decreasing or increasing over time.
be
Equilibrium conditions can
taken as being either static where no net water movement is occur­
ring or the net upward or downward flow has reached an equilibrium val­
ue and is constant.
A comparison of the WF and ASVJC values in Tables 5 and 6 for the
three spoils treatments indicated that the spoils are presently in a
situation where the net downward flow of water is increasing over time,
which will reach some nearly constant rate at some later date.
For
example, the topsoiled revegetated treatment has had the greatest amount
of time in which to stabilize and this treatment showed the greatest ■
amount of drainage from the deep profile.
Also, this treatment had the
least amount of change in drainage with depth and showed the least
change in soil water content at the lower profile depths.
The fact that
the topsoiled revegetated treatment has had the greatest amount of time
to stabilize and also showed the greatest amount of drainage from the
deep profile indicates the drainage from the spoils are apparently
increasing with time.
.>
In the same manner, the lesser amounts of change, in both the soil
water content in the lower profile and the drainage with depth for the
topsoiled revegetated treatment as compared to the two other spoils
treatments, indicates the drainage, on an annual basis, is approaching
an equilibrium value.
As stated earlier, a portion of the water
draining from the 150 cm profile of the spoils treatments is apparent­
ly being stored in the lower profile depths, rather than the entire
flow continuing downward.
Once the storage capacities of these lower
depths are satisfied, greater drainage may then occur to greater
depths.
Assuming no large variations in annual precipitation and evapotranspiration, the change in soil water content on an annual basis
should approach zero.
As this process is taking place, drainage from
the profile should increase to a nearly constant rate,
The lesser
amount of change in soil water content with depth from the topsoiled
revegetated treatment indicates that the storage capacity of the lower
profile depth is being met over time.
The lesser difference between
the 150 cm and deep profile drainage values indicated that the drainage
from the spoils is moving towards an equilibrium value over time.
Thus
it is probable that given enough time, the mine spoils will reach a
condition of equilibrium where both the change in soil water content
in the lower profiles and the drainage rate from the spoils will be
nearly constant.
Once this equilibrium is attained, we can expect a
constant amount of unsaturated flow into the saturated groundwater
zone.
It should be noted that flow into the groundwater zone will
occur before equilibrium with the amount of flow increasing as equil-
52
lbrium is being reached,
This flow of water into the groundwater system through the spoils
is not to be considered an uncommon situation.
Our data show that
flow of water towards the groundwater is also occurring in the native
range and is taking place at 1.5 times the rate as that of the spoils
treatments (Table 4).
Soil Physical Measurements
Various soil physical measurements were made on soil samples from
the four treatment areas.
The objective here was to determine the cause
of the lower rates of soil water movement in the spoils treatments as
compared to the native range as discussed in previous sections.
Results of the bulk density, particle density and modulus of rup­
ture analyses of the surface 0-15 cm soil samples from the four treat­
ments are shown in Table 7.
Each datum presented in the table is a
mean obtained from the three reps of each treatment.
No significant
differences in bulk density were present between treatments.
However,
small increases in bulk density can result in substantial decreases
in water transmission rates in soils (Waldron, et al., 1970),
Therefore,
“3
the lower bulk density of 1.48 g cm
for the native range treatment as
compared to the bulk densities of 1,56, 1.58 and 1.54 g cm
—3
for the
topsoiled honvegetated, topsoiled* revegetated and nontopsoiled revege­
tated spoils treatments, respectively, could result in lower rates of
water movement in the spoils in the surface 0-15 cm;
53
Table 7.
Mean values of bulk density, particle density and modulus of
rupture analyses of 0-15 cm soil samples, Peabody Big Sky
Mine, November, 1974,
Bulk density
(g cm
Treatment
Particle density
)
Modulus of
rupture (bars)
(g cm"3)
Topsoiled
nonvegetated
1.56a
2.42a
Topsoiled
revegetated
I. 58a
2.39a
Nontopsoiled
revegetated
1 ,54a
2.47a
2.17a
Native range
1.48a
2,38a
0.659a
1.360a
..
0.7 34a
Each mean is an average of three replications. Means
within the same column followed by the same letter indicate
no significant difference at the 0.05 level.
The differences in particle density between treatments were not
significant.
The generally accepted value of particle density for soils
derived from quartz-like parent material is 2.65 g cm-^ . These parti­
cle densities of the four treatments (Table 7) are all less than this
value.
Particle density is a measure of the density of the particles
alone, whereas bulk density takes into account the volume of the parti­
cles as well as the pore spaces between these particles.
The closer
the bulk density of a soil is to the particle density of that soil,
the less is the pore volume of the soil.
Assuming these lower values
of particle density are not due to experimental error, less pore volume
was present in these samples with these bulk densities than would occur
54
if these same samples had a particle density of 2.65 g cm
bulk densities.
with these
Since water movement is dependent on the total pore
volume of a soil, these lower particle densities indicate that slower
rates of soil water movement are present in the treatments than would
be expected in soils with a particle density of 2.65 g cm"^ and having
bulk densities shown in Table 7.
However, all four treatments would
be affected to the same degree since no significant difference between
particle density means were shown.
Modulus of rupture is a measure of the degree of soil crusting
which is a function of soil swelling and shrinking processes,
Soil
crusting is affected mainly by the presence of clay, organic matter
and sodium.
High clay contents enhance shrinking and swelling pro­
cesses in the soil and therefore can result in a greater degree of
crusting.
Organic matter tends to stabilize soil aggregates and thus
decreases soil crusting since stable soil aggregates result in a lesser
degree of crusting.
Sodium enhances crusting of the soil by increasing
the diffuse double layer of clays which results in dispersion of the
clay particles.
Soil crusting can affect water infiltration and per­
colation processes and ultimately emergence and growth of vegetation.
i
Although the effects of soil crusting on vegetation is dependent on
the type of vegetation, the critical modulus of rupture is approximately
I bar.
For example, Hanks and Thorp (1957) showed that a modulus of
rupture of this magnitude resulted in a decrease in emergence of grain
55
sorghum seedlings of 80%.
Modulus of rupture values in Table 7 were not significantly dif­
ferent between treatments. Even though these differences were not
significant, the modulus of rupture value of 2.107 bars for the nontopsoiled revegetated treatment was higher than the value of 1,36 bars
for the topsoiled nonvegetated treatment and considerably higher
than those values of 0.734 and 0.659 bars for the topsoiled revegetat­
ed and native range treatments, respectively.
Since the topsoiled
revegetated and native range treatments are well vegetated, the lower
modulus of rupture for these treatments is probably due to the presence
of organic matter in the 0-15 cm horizons which would decrease soil
crusting.
The topsoiled nonvegetated soil material would contain very
little organic matter and therefore would have a greater tendency to
develop soil crusts.
This is substantiated by the higher modulus of
rupture of this treatment as compared to the topsoiled revegetated
and native range treatments.
The high modulus of rupture for the non-
topsoiled revegetated treatment is probably due not only to essentially
little organic matter being present but also to a higher clay and/or
sodium content in the surface as compared to the other treatments.
The greater degree of soil crusting which would be present on
the nontopsoiled treatment as indicated by the modulus of rupture could
be a partial explanation for the poof stand of vegetation on this
treatment.
Crusting would tend to both decrease infiltration of water
56
through the surface and increase the difficulty of plants to emerge
through the surface and develop roots.
Therefore, establishment
of vegetation would be impeded by both lack of water and mechanical
resistance to seedling emergence and root growth.
Bulk density measurements through depth were made for the four
treatments using the core method described in the methodology.
These measurements were made in order to determine any differences in
the bulk densities of the profiles between treatments and to relate
these differences to soil water movement characteristics and to effects
of mining activity on compaction.
A bulk density of 1.3 g cm-^ is the
generally accepted value for a non-compacted soil with bulk densities
of 1.5 g cm ^ or greater being considered as being high.
Results of
the bulk density through depth measurements are given in Table 8.
Bulk densities for the native range profile from 120 to 600 cm were
obtained from bulk density measurements of the single 6 meter native
range core taken in June, 1975.
All other bulk densities are averages
of the three reps from each treatment.
As shown in Table 8, there
were no significant bulk density differences between treatments.
Bowever, the high bulk densities of the native range treatment,
starting at 120 cm and continuing to greater depths, were due
to the sandstone bedrock material beginning at 120 cm.
It was felt
that it was not valid to compare the bulk density of consolidated
sandstone to the unconsolidated spoils material.
Therefore, the bulk
57
*
Table 8.
Bulk densities
through depth in the four treatment areas,
Peabody Big Sky Mine, June, 1975.
Bulk density (g cm 3)
Topsoiled
nonvegetated
Depth (cm)
0- 30
30- 60
60- 90
90-120
120-150
150-180
180-210
210-240
240-270
270-300
300-330
330-360
360-390
390-420
420-450
450-480
480-510
510-540
540-570
570-600
1.79
.1.87
1.68
1.79
1.73
1.69
1.77
1.76
1.74
1.81
1.81
1.77
1.84
1.85
1.93
1.97
1.99
Topsoiled
revegetated
1.69
1.63
1.60
1.65
1.74
1.71
1.82
1.67
1.79
1.78
1.65
‘ 1.68
1.68
1.76
1.72
1.66
1.59
1.60
1.71
1.87
Nontopsoiled
revegetated
Native
range
1.64
1.58
1.73
1.88
1.72
1.60
1.89
1.74
1.79
1.75
1.75
1.86
1.91
1.73
1.74
1.79
1.66
1.64
1.76
1.40
1.38
1.51
1.57
1.96
1.87
1.90
1.90
1.94
1.94
1.98
2.00
2.05
2.05
1.86
1.98
1.94
1.77
1.76
1.81
Profile
mean
1.81a
1.70*
1.75*
1.83*
120 cm
Profile
mean
1.78*
1.64*
1.71*
1.46b
*
With the exception of the 120-600 cm depth in the native
range profile, each datum is a mean of three replications.
Means followed by the same letter indicate no significance
at the 0.05 level.
58
density means of the 120 cm profile, which would exclude the sand­
stone layer, for each treatment are also shown in Table 8,
It was \
found that the 120 cm native range profile mean bulk density of 1.46
g cm"^ was significantly lower than the mean bulk density of 1,78,
1.64 and 1.71 g cm ^ for the topsoiled nonvegetated, topsoiled
revegetated and nontopsoiled revegetated treatments, respectively.
No significant differences were present between these bulk density ■
means of the three spoils treatments.
It is apparent from these
higher bulk densities in spoils near the surface that compaction of
the spoils occurred during the replacement and contouring of the
overburden.
Since compaction results in decreased soil water move­
ment, the lower rate of soil water flow in the mine spoils as com­
pared to the native range site, shown by the water movement model,
could be explained in part by the compaction of these spoil areas.
Particle size analyses through depth were performed for the
four treatments in order to determine any differences in particle
size distribution between treatments.
Results of these analyses are
given in Table 9.
Since we were not able to take samples past 120 cm in the native
range treatment using our drilling equipment, the native range core
taken in June 1975 was used for particle size analyses past the 120
cm depth.
In general, the spoils treatments had higher amounts of
clay and silt throughout the profile than did the native range treat­
ment.
59
Table 9.
Particle size distribution through depth of the four treat­
ment areas, Peabody Big Sky Mine. Samples for the 120-600 cm
depths for native range were taken in June, 1975. All other
samples were taken in November, 1974.
Treatment
Depth (cm)
Topsoiled
nonvegetated
0- 15
15- 60
60- 90
90-120
120-150
150-180
180-240
240-300
300-360
360-480
Topsoiled ■
revegetated
0- 15
15- 60
60- 90
90-120
120-180
180-240
240-300
300-360
360-420
420-480
480-540
Nohtopsoiled
revegetated
0- 15
15- 60
60-120
. 120-180
180-240
240-300
300-360
360-420
420-480
480-600
.
% sand
% silt
38.4
16.6
15.6
15.6
14.6
19.6
29.1
23.6
29.6
16.3
35.8
42,8
40.8
42.8
46.8
46,2
30.5
38.0
41.0
39,7
68,0
33.9
40.5
29.2
24.9
33.3
28.7
35.3
33.0
23.0
■ 26.0
31.1
29.9
23.5
26.5 .
24.9
28,9
27.0
28.4
28.2
25,7
% clay
Textural
class
25,8
40.6
43.6
41.6
38,6
34.4
40.4
38.4
38.4
44.0 '
loam
silty clay
silty clay
silty clay
silty clay loam
silty clay loam
clay
clay loam
clay loam
clay
13,3
36,8
33.5
' 36.8
40.2
37.5
38.8
32.4
49.0
41,0
32.0
18.7
29.3
26.0
34.0
34.9
29.2
32.5
32,3
29.0
36.0
42.0
sandy loam
clay loam
clay loam
clay loam
clay loam
clay loam
clay loam
clay loam
clay loam
clay loam
clay
37,3
37.5
36.5
39,8
46.3
41,3
42.3
37.0
38.8
43,4
31.6
35.6
40.0
. 33.7
28,8
29.8
30.7
34,6
33.0
30,9
clay
clay
clay
clay
clay
clay
clay
clay
clay
clay
loam
loam
loam
loam
loam
loam
loam
loam
loam
loam
60
Table 9 (cont'd)
Treatment
Depth (cm)
0- 30
30- 60
60- 90
90-120
120-150
150-180
180-210
210-240
240-270
270-300
300-330
330-360
360-390
390-420
420-450
450-480
480-510
510-540
540-570
570-600
'
% sand
% silt
% clay
39.7
33.5
27.6
31.6
28.8
38.8
40.8
46.8
44.4
46.4
56.4
54.4
53.6
53.6
59.6
61.6
57.6
69.6
67.6
65,6
33.6
38.2
34.4
38.4
47.6
39.6
43.6
39.6
41,6
39.6
31.6
33.6
33,6
33.6
25.6
25.6
27.6
17.6
19.6
21.6
26.7
29.3
38.0
30.0
23.6
21.6
15.6
13.6
14.0
14.0
12.0
12.0
12.8
12.8
14,8
12.8
14.8
12.8
12.8
12.8
Textural
class
loam ■
clay loam
clay loam
clay loam
loam
loam
loam
loam
loam
loam
loam
sandy loam
sandy loam
sandy loam
sandy loam
sandy loam
sandy loam
sandy loam
sandy loam
sandy loam
With the exception pf the 120-600 cm depth of the native range
profile, each datum is a mean of three replications.
Since silt and clay can limit soil water movement (Diebold, 1954;
Warkentin, 1971), this could partially explain the lower rate of water
movement in the spoils indicated by the water movement model.
The lower percentages of clay and silt in the topsoil of the two
topsoiled spoils treatments compared to the nontopsoiled spoils treat­
ment resulted in higher infiltration rates as will be discussed in
detail in a later section.
Lower infiltration rates result in less
61
water entering the root zone and greater erosion due to runoff.
Thus,
the higher silt and clay content of the 0-15 cm depth in the nontopsoiled revegetated treatment could explain, in part, the poor stand
of vegetation which was obtained on this site.
The particle size distribution of the three spoils treatments
shown in Table
9
indicates that the sand, silt and clay particles
are present in approximately equal proportions.
As pointed out by
Warkentin (1971), compaction of a soil is most easily achieved when
this situation exists.
Due to this particle size distribution, the
spoils are more susceptable to compaction during resurfacing opera­
tions which could explain the higher bulk density of the spoils shown
in Table 8.
Soil desorption curves show the water loss characteristics of soils
with decreasing matric potential (^m) where a decrease in
a greater negative number.
denotes
These curves are useful in showing the
plant available water present at any given
Soil desorption curves
were constructed for the 0-15 cm soil samples from the four treatments.
No moisture determinations were-, made at -3 atmospheres due to equip­
ment malfunction.
These curves are shown in Figure 13,
Little varia­
tion in soil desorption characteristics were shown between treatments.
All treatments showed a rapid decrease in water content with decreasing
matric potentials to -1.0 atm.
The rate of water loss at matric poten­
tials from -1.0 to -15 atm was much less for all treatments than at
62
O
A
•
*
Topsoiled nonvegetated
Topsoiled revegetated
Nontopsoiled revegetated
Native range
C 20
O
-3
-G
-9
-12
-15
Matric Potential (atm)
Figure 13.
Soil desorption curves of 0-15 cm soil samples
from the four treatment areas, Peabody Big Sky
Mine, November, 1974. Each datum point is the
average of three replications.
63
matric potentials from -0.1 to -I.atm.
Desorption curves of this
type indicate a sandy or loamy textured soil.
Except at high matric
potentials, little water would be available for uptake by plants.
Clay Mineralogy
Representative soil samples from the 0-15 cm depth of each
treatment were taken in August, 1975 for clay mineralogy analysis.
Knowledge of the clay minerals present in the treatments was desired
in order to determine the possible effects of the clay fraction on
water movement in the treatments.
The clay mineralogy of these samples was determined using x-ray
diffraction techniques.
Particle size analyses were performed in
conjunction with the clay mineralogy analyses.
results of these analyses.
Table 10 presents the
Particle size distributions for the sur­
face samples from each treatment shown in this table coincide closely
with those shown in Table 9 with the exception of the nontopsoiled
revegetated treatment.
Here, the silt content of 54% was considerably
higher for the sample from this treatment taken in August, 1975
as
compared to the silt content of 37.3% shown in Table 9 for the November,
1974 sample.
This indicates a possible breakdown of the blue shale
overburden present on the surface of the nontopsoiled revegetated
treatment to silt size particles over time due to weathering.
Coarse
blue shale fragments were on the surface and in the root biosphere of
this treatment.
The fragments are very subject to weathering. When placed
64
in water, solid blue shale fragments will break down in a matter of hours.
This increase in silt content could have a large effect on water
movement since the work of Diebold (1954) showed that high silt con­
tents resulted in lower permeability and infiltration of water in the
soil.
The weathering of the blue shale into silt size particles
could conceivably decrease water movement in the two topsoiled spoil
treatments as well, since the overburden underlying the topsoil of
these treatments contains considerable amounts of blue shale as was
evident from core samples of these spoil treatments.
The weathering
of the blue shale in the topsoiled nonvegetated and topsoiled reveg­
etated treatments would be less rapid since the shale is not as direct­
ly exposed to fopceq of soil formation such as precipitation, temper­
ature, etc..
However, given enough time, it could be assumed that the
silt content of the blue shale overburden in these spoils treatments
would increase, possibly resulting in decreased soil water movement.
Results of the clay mineralogy analyses in Table 10 indicate the
dominant clay minerals in the surface soil of the four treatments are
illite and kaolinite with small amounts of chlorite.
The topsoiled
nonvegetated treatment contained small amounts of smectite and vermiculite which were not present in the other treatments.
The native
range treatment showed a higher illite content than was present in
the spoils treatments.
Illite, kaolinite and chlorite are non-expanding lattice clays.
%
Table 10.
Particle size distribution and clay mineralogy of representative surface depth
soil samples from the four treatment areas , Peabody Big Sky Mine, August, 1975.
k
Particle size distributionL Textural
Type and predominance
of clay mineral
% sand
% silt
% clay
class
Topsoiled
nonvegetated
62
22
16
sandy clay
loam
low
mod
mod
low
trace
Topsoiled
revegetated
67
19
14
sandy clay
loam
O
mod
mod
low
O
Nontopsoiled
revegetated
25
54
21
silt loam
O
mod
mod
low
O
52
34.
14
loam
O
high
mod
low
.0
Treatment
Native range
.
high = 50-75%
moderate = 25-50%
low = 5-25%
trace = less than 5%
Smectite Illite Kaolinite Chlorite Vermiculite
Ln
66
Clay minerals of this type exhibit little change in structure upon
wetting and therefore do not affect water movement to,any great ex­
tent.
Smectite and vermiculite are expanding lattice clays.
These
types of clay mineral swell upon wetting which can result in decreased
water movement.
The presence of smectite and vermiculite in the
topsoiled nonvegetated treatment indicates that water movement could
be restricted to some extent due to expansion of' these clay minerals
upon wetting.
However, the predominant clay minerals in this treat­
ment are of a non-expanding nature which would tend to overshadow the
detrimental effects of the small amounts of smectite and vermiculite.
The clay mineralogy of the topsoiled revegetated, nontopsoiled
reyegetated and native range treatments is completely dominated by
illite, kaolinite and chlorite which indicates that water movement in
the surface material of these treatments is not affected by any con­
siderable amounts,of expansion of clays in the soil.
Thus, the lower
rates of water movement in the spoil treatments compared to the native
range site shown by the model cannot be explained by high contents of
expanding lattice clays.
Infiltration Rates■
Infiltration rates of the four treatments were measured and related
to soil water drainage.
Infiltration characteristics of the four treat­
ments are shown in Figure 14.
Each line was determined by infiltration
data obtained for a rep. within a treatment.
Mean infiltratiqn rates of
Infiltration (c m /h r )
O Topsoiled nonvegetated
A Topsoiled revegetated
• Nontopsoiled revegetated
A Native range
15
20
Time (m inutes)
Figure 14.
25
Infiltration rates of the four treatment areas, Peabody
Big Sky Mine, August, 1975. Each line represents data
for a rep within the treatment. Brackets followed by
same letter indicate no significant difference between
means at the 0.01 level.
68
of 11.90, 7.81, 4.46, and 1.87■cm/hr for the native range, topsoiled
revegetated, topsoiled nonvegetated and nontopsoiled revegetated
treatments, respectively, were all significantly different at the
0.01 level.
These differences in infiltration rates between treat­
ments can be attributed to two major factors, the first of which is
vegetation.
Vegetation tends to decrease runoff allowing greater
infiltration of rainfall and protects the soil ftorn, the beating
action of the raindrops.
The effect of vegetation was shown by the
higher infiltration rates of the native range and topsoiled revege­
tated treatments compared to the infiltration rates of the topsoiled
nonvegetated and nontopsoiled revegetated treatments of which both
had essentially no vegetation.
The higher rate of infiltration on
the native range as compared to the topsoiled revegetated treatment
could be due to the greater degree of soil structural development
of the native range.
The second factor affecting infiltration appears to be the pres­
ence of topsoil.
Since both the topsoiled nonvegetated and nontop­
soiled revegetated treatments are essentially void of vegetation, the
presence of topsoil is the probable remaining variable which affected
infiltration rates.
The significantly higher infiltration rate of
the topsoiled nonvegetated treatment as compared to the nontopsoiled
revegetated treatment indicates that the presence of topsoil can in- '
crease infiltration.
69
At least two factors could be responsible for the lower infil­
tration rates of the nontopsoiled revegetated treatment as compared
to the other spoil treatments.
First, the surface of the nontop­
soiled revegetated treatment had considerably higher silt and clay
contents than the topsoil of the other two spoils treatments (Table
9).
These higher.amounts of silt and clay would tend to decrease
the infiltration rate of water.
Second, the greater degree of soil
crusting on the nontopsoiled treatment, as indicated by the modulus
of rupture shown in Table 7, would tend to further decrease infiltra­
tion.
These differences between the nontopsoiled and the topsoiled
spoil treatments indicate the value of topsoiling as a management ■
tool.
Soil water drainage from a profile would, in part, be dependent
on the amount of infiltration into a profile.
Thus, it appears these
differences in infiltration rates could result in significantly dif­
ferent amounts of drainage between treatments.
Saturated Hydraulic Conductivity
The rate of water movement in a soil is dependent" On the hydraulic
conductivity of that soil.
Hydraulic conductivity is the effective
flow velocity of water in soil, generally expressed as centimeters per
unit of time.
Slow rates of saturated hydraulic conductivity are gener
ally considered as being in the range of 3.0 to 12.0 cm/day whereas
70
rapid rates are
considered as being in the range of 300^600 cm/day
(O'Neal, 1952).
Saturated hydraulic conductivities through depth
were determined to see if any differences between treatments existed.
The saturated hydraulic conductivity through depth for the four
treatments is shown in Figure 15.
The mean saturated hydraulic con­
ductivity of 4.87 cm/day for the native range treatment was signifi­
cantly greater compared to the mean hydraulic conductivities of the
spoil treatments.
No significant differences were present between
the spoils saturated hydraulic conductivities of 1.52, 1.31 and 1.30
cm/day for the topsoiled nonvegetated, topsoiled revegetated and nontopsoiled revegetated treatments, respectively.
Saturated hydraulic conductivity was determined using disturbed
samples which would result in the destruction of any structure present..
Since the presence of structure would probably result in greater rates
of water movement, the hydraulic conductivity of the upper profile of
the native range would be greater than that shown in Figure 15.
The
saturated hydraulic conductivity for the spoil treatments shown in
Figure 15 compared to actual hydraulic conductivities under field con­
ditions, would probably not vary greatly since the spoils are in essence
disturbed soils.
The difference in the saturated hydraulic conductivity of the
native rapge as compared to that of the spoils treatments was evident
in the flooding portion of the water movement model procedure.
Appli-
71
Hydraulic Conductivity
Profile Mean
Topsoiled nonvegetated
Topsoiled revegetated
Nontopsoiled revegetated
Nativerange
480
1. 5 2 b
1.31 h
/.3 0 b
4 .8 7 a
600
)
2
4
6
8
IO
Hydraulic Conductivity, K (cm /d ay)
Figure 15.
Saturated hydraulic conductivity through
depth for disturbed samples from the four
treatment areas, Peabody Big Sky Mine,
September, 1975. Means followed by the
same letter indicate no significant
difference at the 0.05 level.
72
cation of approximately four to five times as. much water per unit
time was necessary on the native range plots compared to the spoils
treatments in order to maintain a constant ponding level.
The consolidated layer of sandstone beginning at the 120 cm
depth of the native range would possibly exhibit lower hydraulic
conductivities than those shown for the 0-120 cm depths.
However,
cracks and fissures in the sandstone layer were apparently present
and transmitted water readily.
That these cracks and fissures were
present was substantiated by the greater amount of water necessary
during flooding.
Also, neutron probe readings on the native range
treatment through the entire course of the study did not indicate
the presence of a perched water table at any time above the sand­
stone layer.
If the sandstone layer was impermeable to water, a
perched water table above this layer would have been evident.
These differences in hydraulic conductivity between treatments
correlate closely with differences in rate of water movement shown
by the flow model.
Both the saturated hydraulic conductivity and the
model showed greater rates of water movement in the native range as
compared to the spoils with little differences in movement rates
between the spoils treatments.
Solute Movement
Chemical analyses of core samples from each treatment were per­
73
formed on a twice yearly basis so that comparisons of the solute con­
centrations between treatments could be made and any trends in solute
movement over time could be detected.
However, at the writing of
this thesis, the sampling, period covered only a one year interval.
This time span was too short to detect any definite trends in solute
movement.
Therefore, the discussion in this section will be limit­
ed mainly to a comparison of solute concentrations between treatments
in relation to plant, nutrition and any possible physiochemical effects
on the soil.
Chemical analyses of NO^-N and NH^-N were done since these, sol­
utes are the main sources of available nitrogen for plant uptake.
Also, high concentrations of nitrates in water can be toxic to both
livestock and humans.
Drinking water having a nitrate concentration
3
of 10 ppm or greater is considered toxic to humans , with livestock
having a somewhat higher tolerance.
3
If high concentrations of NO -N
were present in the treatments, any drainage could result in the
leaching of nitrate into the groundwater system, ultimately increasing
the nitrate concentration of the groundwater.
Results of N O y N analyses are given in Figure 16.
The topsoiled
nonvegetated treatment showed a decrease in profile mean concentrations
over time indicating possible movement of nitrates out of the profile.
^U. S.'Public Health Service standards
SOIL
O
2
4
6
8
IO
12
O
2
NO3-N (ppm )
4
6
8
IO
12
O
2
4
6
8
IO
12
200
S p rin g , 1975
N O -N
P ro file Means
300
F a ll, /974
400
NOi N
F a ll, 1975
N O -N
P ro file Means
2 .5 3
°
a
3 86
2.4/
•
»
6 IO
3 94
7.20
0 48
I .6 0
a
I.11
P ro file Means
° Topsoiled
no nvegetated 4.30-6 Topsoiled
re v e g e ta te d
2.24
• N ontopsoiled
re v e g e ta te d
4.57 ,
500
* N ative range 0 .7 1
1
□ N ative ra nge
(6 m core.)
600
Figure 16.
Soil profile distribution of NO,-N from November, 1974 to October, 1975,
Peabody Big Sky Mine. Except for the 6 m native range profile, each datum
is a mean of three replications.
CS
75
If vegetation were present on this treatment, the resulting plant
uptake of NOg-N could result in a lesser amount of movement.
No
trends in NOg-N movement in the remaining treatments were evident.
However, increasing concentrations of NOg-N over time were evident
in the lower profile of the topsoiled revegetated and nontopsoiled
revegetated treatments.
These increases could be due to downward
movement and accumulation at lower profile depth.
highly, mobile in a soil system.
Nitrates are
The soil water which has been
shown to be draining from the spoils and native range probably
resulted in any translocation of nitrates shown in Figure 16.
At profile depths below 50 cm, the spoils treatments showed
substantially higher NOg-N concentrations than were present in the
native range treatment.
The Ft. Union blue shale present in the
spoils generally has high amounts of fixed NH^-N (Power, et al,
1975).
Upon exposure to weathering during mining activity, the
NH^-N can be released and converted to NOg-N through microbial acti
vity.
These higher NOg-N levels in the spoils could be partially
contributed to this mechanism.
In addition, the higher levels of
NO^-N in the topsoiled revegetated and nontopsoiled revegetated
spoil treatments could be attributed to the addition of nitrogen
fertilizer to these treatments at the time the seeding operations
took place.
76
From the standpoint of plant nutrition, greater amounts of
NOg-N would be available in the spoils for plant uptake.
However,
downward movement of this solute could result in a substantial in­
crease in the NOg-N level of the groundwater system in this area.
Results of NH^-N analyses are given in Figure 17.
The spoil
treatments showed a decrease over time in the profile mean NH^-N
concentration.
It is felt that this decrease in NH^-N was due to
conversion into NO^-N rather than loss due to movement to a deeper
depth.
In general, the NH^-N concentrations of the native range
profile were not substantially different from those of the spoils
treatments.
Therefore, vegetation should do equally well from the
standpoint of available NH^-H on all the treatments.
Analyses of PO^-P were performed since this is the form of
phosphorus most readily utilized by plants.
ses are given in Figure 18.
Results of these analy­
No trends in solute movement were
<
indicated with the mean concentrations of PO^-P in each profile
showing little change over time.
-PO^-P in soils is a non-mobile
anion due to the interaction of phosphates and clay minerals.
Thus,
large differences in profile distribution of PO^-P over time would
not be expected.
In general, the levels of PO^-P in the surface 100 cm profile
depth of the native range were higher than that of the spoils treat-
SOIL NH-N (ppm)
0
Figure 17.
4
8
12
O
4
8
12
Soil profile distribution of NH^-N from June to October, 1975,
Peabody Big Sky Mine. Except for the 6 m native range profile,
each datum is a mean of three replications.
SOIL
1 2
P O -P (ppm)
3
4
5
Oo
Figure 18.
Soil profile distribution of PO4-P from November, 1974-October, 1975,
Peabody Big Sky Mine. Except for the 6 m native range profile, each
datum is the mean of three replications.
79
merits.
This indicates that vegetation present on the spoils would
have less PO^-P available for uptake than on native range until the
roots were established past 100 cm.
Ammonium acetate (NH^OAc) extractable calcium, magnesium, sodium
and potassium were analyzed since these cations are major plant nuttients.
Also, the relative concentration of these three elements to
each other can be used to determine possible detrimental effects of
sodium on soil physical properties.
The quantity of a cation which
can be extracted by NH^OAc is also an indication of the quantity of
that cation which is held on the exchange complex of the clay frac­
tion.
Cations which are held on the exchange complex are available
for plant uptake.
Values of NH^OAc extractable calcium are presented in Figure
19.
No trends in the movement of calcium in the four treatments
were evident.
In general, profile concentrations of NH^OAc extract-
able calcium in the spoil treatments were somewhat higher than those
of the native range.
The availability of calcium for plant uptake
should be approximately the same in all treatments.
The calcic hor­
izon which is commonly present at the 50 to 100 cm profile depths
in the native range is evident in the spring and fall, 1975 analyses.
Figure 20 shows the distribution of the NH^OAc extractable mag­
nesium in the four treatments.
nesium was present.
No evidence of movement of the mag­
Also, little difference in profile mean concen-
s o i l e x t r a c t a b l e nh oac
O
20
40
60
80 0
20
40
Ca (m e q /io o g )
60
80 0
20
40
60
80
200
X
300
F a ll, 1974
Ca
P ro file Means
o Tbpsoiled
no nve g e ta te d 30.3
a Topsoiled
re v e g e ta te d
35. 1
• N ontopsoile d
re v e g e ta te d
34.6. -
400
5 00
* N a tive range
S p rin g , 1975
Ca
P ro file Means
F a ll, 1975
Ca
P rofile Means
35.0
36 8
30.9
28.0
30.3
40.8
37.4
23 9
2 6 .2
a N ative range
( 6 m. core)
600
Figure 19.
Soil profile distribution of NH^OAcextractable calcium from November, 1974
to October, 1975, Peabody Big Sky Mine. Except for the 6 m native range
profile, each datum is a mean of three replications.
Mg (m e q /io o g )
s o il e x t r a c t a b l e nh oac
O
4
8
12
16 O
4
8
4
12
16 O
4
8
12
16
200
F a ll, 1975
6 . 12
P rofile Means
6 .7 5
•
4 91
6.68
6.60
7 .2 0
6/3
°
7.30
P ro file Means
F a ll, /974
400
P ro file Means
Topsoiled
nonvegefated 6 . 7 5 - a Topsoiled
re v e g e ta te d
6 48
• N ontopsoiled
re v e g e ta te d
4.97
500
a N ative ra nge
2 .8 9
a N ative range
(6 m. co re )
600
Figure 20.
Soil profile distribution of NH4OAc extractable magnesium from November,
1974 to October, 1975, Peabody Big Sky Mine. Except for the 6 m native
range profile, each datum is a mean of three replications.
82
trations of extractable magnesium was shown.
This lack of difference
indicates that the availability of magnesium for plant uptake is the
same for both the spoils nad native range treatments.
The NH^OAc extractable potassium analyses results are presented
in Figure 21.
For all sampling dates, levels of extractable potassium
at 0-60 cm depths were higher in the native range than the spoils treat­
ments.
Thus, less potassium'is available for uptake by plants in the
spoil treatments which could result in a potassium deficiency for vegtation present on the spoils.
A possible explanation for the higher
potassium levels in the native range site is the high illite content
in the native range as shown by the clay mineralogy analysis (see
earlier section).
Illite contains high levels of fixed potassium which
can be extracted by plants over long periods of time.
Upon the death
and decay of the plant, the potassium is returned to the soil where it
is either taken up by plants again or held on the exchange complex.
Over long periods of time, the continued extraction of potassium from
illite results in a substantial increase in potassium levels in the
root zone.
Since the native range site has been under constant vegeta­
tion for a long period of time, this mechanism would explain the higher
concentrations of potassium present.
Results of the NH^OAc extractable sodium analyses are given in
Figure 22.
In general, the profile means increased with time.
This
increase could be due to the infiltration and percolation of runoff
SOIL EXTRACTABLE,NH
OAc
K (m eq/IO O g)
0.8 O
0.8 O
200
F a ll, 1975
I
P ro file Means
300
°
a
0.28
0 .3 0
P ro file Means
0 16
0 .2 8
0.22
0 .3 7
0 .3 2
F a ll, /974
400
P ro file Means
° Topsoiled
nonvegetated 0 . 1 2 -A Topsoiled
re v e g e ta te d
0 .2 2
• N onfopsoiled
re v e g e ta te d
O. 17
500
a N ative range
0 .4 4
□ N ative range
( 6 m. core)
600
Figure 21.
Soil profile distribution of NH4OAc extractable potassium from November,
1974 to October, 1975, Peabody Big Sky Mine. Except for the 6 m native
range profile, each datum is a mean of three replications.
SOIL EXTRACTABLE
NH4 OAc
N a(m eq/IO O g)
CD
Figure 22.
Soil profile distribution of NH4OAc extractable sodium from November, 1974
to October, 1975, Peabody Big Sky Mine. Except for the 6 m native range
profile, each datum is a mean of three replications.
85
water having a high sodium content.
However, if this were clearly
the case, the upper profile depths would show an initial increase in
sodium, with the sodium levels of lower profile depths increasing over
time as downward flow of soil water occurred.
Since the entire profile,
in general, showed an increase in extractable sodium, the increase is
probably due to chemical variability between sample sites rather than
to any infiltration and downward movement of high sodium runoff water.
The exchangeable sodium percentage (ESP) is defined by Equation
10 .
'
ESP= __________ exchangeable Na__________ _ x ]qq
cation exchange capacity (CEC)
where Na and CEC are in meq/100 g
(10)
ESP is used as an indicator of soil physical problems due to clay
dispersion by the exchangeable sodium.
An ESP of 15 or greater is
used as the criterion for classification of a sodic soil.
Serious
soil physical problems can occur on a sodic soil.
CEC is the sum of all exchangeable cations present in a system.
Since calcium, magnesium, sodium and potassium represent the majority
of the cations generally present on the exchange complex of clays and
NH^OAc extractable cations approximate the exchangeable cations, CE C ,
can be approximated by the sum of the NH^OAc extractable cations which
were determined. ■
,
86
Using cation exchange capacities approximated by this method and
the. NH^OAc extractable sodium analyses in Figure 22, no ESP greater
than 3.5 was obtained.
Thus, the levels of ESP found in the four treat-:
ment profiles are well below the critical ESP value of 15.
No soil
physical problems due to exchangeable sodium would be present in the
spoils
or the native range.
Analyses of water soluble calcium, magnesium and sodium were nec­
essary in order to calculate the sodium adsorption ration (SAR), defined
by Equation 11.
SAR = (Na) / (((Ca) + (Mg))/2)%
(11)
where all concentrations are in meq/L
In general, SAR values greater than 10 indicate that soil physical
problems, such as clay dispersion, puddling, soil crusting and decreased
percolation rates of water, will occur due to the sodium present.
The profile distributions of water soluble calcium for the two
sampling dates are given in Figure 23.
The concentrations of water
soluble calcium in the spoil treatments were substantially higher than
' ih the native range site.
These higher calcium concentrations could
result in lower values of SAR in the spoils by increasing the value
of the denominator in Equation 11.
Thus, the detrimental affects of
sodium could be less in the spoils as compared to native range.
SOIL SOLUBLE
IO
20
30
O
HO
2
Ca (rneqA)
IO
20
30
IOO
200
Fall, 1975
Ca Profile Means
o Topsoiled
nonvegetaied 26.51
Topsoiled
revegetated
Nontopsoiled
revegetated
Native range
-- a Native range
(6 m. c o re )
S
X 300
h~
CL
UJ
Q 400
500
6 0 0
Figure 23.
Soil profile distribution of water soluble calcium from June to
O c t o b e r , 1975, Peabody Big Sky Mine. Except for the 6 m native
range profile, each datum is a mean of three replications.
88
Results of the water soluble magnesium analyses are shown in
Figure 24.
Little differences in magnesium concentrations in the
spoil treatments over time were shown.
The native range showed higher
initial concentrations of magnesium and lower concentrations in the
fall than did the spoils treatments.
The water soluble magnesium in
the native range treatment showed a marked decrease over time.
This
decrease could possibly be due to translocation of magnesium during
the flooding portion of the water model testing period.
Figure 25 shows the results of the water soluble sodium analyses.
No definite trends in sodium movement could be determined in the spoil
treatments.
As with the water soluble magnesium, the water soluble
sodium in the native range also decreased considerably with time.
This
was possibly due to the large water volumes used in the flooding pro­
cedure on the native range treatment resulting in downward displacement
of the sodium.
Results of the SAR calculations are given in Figure 26.
ues, over time showed little change in the spoil treatments.
SAR val­
The de­
crease in SAR over time for thenative range resulted from the decreases in water soluble sodium and, to a lesser degree, magnesium which
were discussed previously.
All SAR values shown in Figure 26 were
well below the critical value of 10.
Thus, the levels of water sol­
uble sodium present in the treatments should not result in any detri­
mental affects to soil physical properties.
These SAR and ESP values
indicate that the lower rates of water movement in spoils, as compared
SOIL SOLUBLE H O Mg (rneq/O
20
30
40
50
O
IO 20
30
40
50
IOO -
200
-
I
\—
CL 300 LU
Q
400 -
Spring, 1975
Mg
Profile Means
Fall, 1975
Mg
Profile Means ~
° Topsoiled
nonvegetated 22.1A Topsoiled
revegetated 25.8
• Nontopsoiled
revegetated 24.4
+ Nativerange 12.9
Native range
(6 m.core)
500 -
6 0 0
Figure 24.
Soil profile distribution of water soluble magnesium from June to
October, 1975, Peabody Big Sky Mine. Except for the 6 m native
range profile, each datum is a mean of three replications.
SOIL SOLUBLE
Na (meq/O
H2°
O
4
Figure 25.
8
12
O
4
8
12
Soil profile distribution of water soluble sodium from June to
October, 1975, Peabody Big Sky Mine. Except for the 6 m native
range p r o f i l e , each datum is a mean of three replications.
SODIUM ADSORPTION RATIO
2
3
4
0
1
2
3
4
T
Fall, 1975
SAR Profile Means
Topsoiled
nonvegetated 0 .4 8
Topsoiled
revegetated
Nontopsoiled
revegetated
Native range
Spring, 1975
SAR Profile Means
0 .9 5 1.18
0.81
Native range
(6 m. core)
600
Figure 26.
Soil profile SAR levels from June to October, 1975, Peabody Big
Sky Mine. Except for the 6 m native range profile, each datum is
a mean of three replications.
92
to the native range, shown by the water movement model, are not due
to dispersion of the clay by high concentrations of sodium.
Information on the salt content of the treatment profiles was
desired since high contents of salt in the soil can affect plant
growth.
High salt concentrations in a soil result in an increased
osmotic or solute potential of the soil.
This increase in osmotic
potential results in a decrease in the water movement gradient towards
the plant causing water stress condition in the plant.
Information
on the salt content of the treatments was obtained from electrical
conductivity measurements on saturated paste extracts.
Since the
electrical conductivity of a soil increases with increasing salt con­
tent, electrical conductivity is a measure of the salt level of a soil.
The results of the electrical conductivity measurements are pre­
sented in Figure 27.
Electrical conductivity varied little between
treatments of over time.
This indicates that salt levels of the four
treatments were not substantially different, and that little overall
I
solute movement occurred over time.
Soils having electrical conductivities greater than 4 mmhos/cm
are classified as saline soils.
Saline soils are generally non­
productive due to the detrimental effects of the high salt level
to plant growth caused by the higher osmotic potential of the soil.
The electrical conductivities shown in Figure 27 indicate that, in
general, the 0-60 cm profile depths of the four treatments would be
SOIL ELECTRICAL CONDUCTIVITY (mmhos/cm)
p
300
S p rin g , 1975
EC
- - P ro file Means
*
400
500
600
52
F a ll, 1975
EC
P ro file Means
*
46
F a ll, 1974
EC
P ro file Means
Topsoiled
n o n vege laled 5 . 4 0
_
* Topsoiled
re v e g e ta te d
• N ontopsoiled
re v e g e ta te d
4 .5 0
3 .1 0
- * N a tiv e ra nge 0 . 6 5
o N a tive range
( 6 m c o re )
Figure 27.
Soil profile distribution of salt from November, 1974 to October, 1975,
Peabody Big Sky Mine. Except for the 6 m native range profile, each
datum is a mean of three replications.
VO
W
94
classified as non-saline.
Thus, vegetation with a 60 cm rooting
depth would not be adversely affected by the salt levels present.
The higher electrical conductivities found in the lower profile
depths indicate that substantial amounts of salts were present.
This arrangement indicates that salts could have been leached from
the profile resulting in salt moving towards the groundwater.
The pH of a soil affects plant growth by its indirect effect on
governing the availability of plant nutrients and, when excessively
high or low, by injuring the plant directly or by upsetting the meta­
bolism oi the roots.
The pH of soils in the semi-arid West generally
ranges from 7 to 8.
Table 28 presents the results of the pH measurements.
The top-
soiled revegetated treatment was acidic (<pH 7) throughout most of
its profile.
Profiles of the other three treatments were generally
above pH 7.
However, none of the pH levels were excessively high or
low.
The pH of the surface 100 cm of each treatment was generally
in the range of 7 to 8.
No detrimental effects on plant growth due
to pH should be expected.
As stated earlier, the time span of the study was too short
to detect any definite trends in movement of the various solutes.
However, these data presented in this section will provide -good
baseline information.
Comparison of these data with solute data
obtained at later dates at these same sites should provide informa-
SOIL pH
6.0
6.5
7.0
75
8.0
8.5
9.0 6.0
6.5
70
75
8.0
8.5
9.0 6.0
6.5
70
8.5
9.0
VO
Vl
Figure 28.
Soil profile pH levels from November, 1974 to October, 1975, Peabody Big
Sky Mine. Except for the 6 m native range profile, each datum is a mean
of three replicates.
96
tion on solute movement in strip mine spoils and native range.
The fact that drainage from the spoils and native range is
occurring (see earlier sections), downward movement of solutes
towards the groundwater will likely occur over time.
The solute
concentrations presented in this section indicated that, in general,
the concentrations of the solutes in the spoil treatments were not
substantially differenet from those of the native range.
This small
difference in solute concentrations would result in approximately the
same quantities of solutes available for translocation.
The higher
rates of water movement in the native range shown by the water move­
ment model as compared to the spoil treatments indicate that possibly
greater amounts of solute movement into the groundwater would occur
from the native range than from the spoils.
fr
SUMMARY AND CONCLUSIONS
A study was initiated in November, 1974 at the Peabody Big
Sky Mine near Colstrip, Montana to determine soil water and solute
movement in strip mine spoils.
Three spoils treatments, consisting
of topsoiled nonvegetated, topsoiled revegetated and nontopsoiled
revegetated spoils, and a native range site were studied.
Each
treatment consisted of three replications.
An unsaturated soil water movement model was shown to be applic­
able to mine spoils and native range in the study area.
Use of the
model indicated that the quantity of unsaturated flow in the native
range was approximately 1.5 times greater than in the spoils.
Calculation of the lnt situ soil water budgets, with neutron
scattering soil moisture equipment, indicated that drainage from the
spoils and native range was occurring with drainage from the native
range approximately 1.6 times greater than the average drainage from
the spoils. Both the water movement model and the jLn situ soil water
budgets showed the same trends in soil water flow between the spoils
and native range, with the water budget indicating greater amounts
of drainage for all treatments than did the water movement model.
The
in situ soil water budgets indicated that water flow in the spoils is
evidently moving towards a state of equilibrium where the quantities
of the downward flow of water will be nearly constant at some time in
the future.
Soil physical analyses indicated that the lower quantities of soil
98
water movement, shown by both the water movement model and the in
situ measurements, in the spoils compared to native range were due
to compaction and higher contents of clay and silt.
Compaction in
the spoils was indicated by the spoil bulk densities of 1.6 to 1.9
__g
g cm
which were approximately 54% higher than those of the native
range.
Clay mineralogy analyses of 0-15 cm surface samples indicated
that the dominant clay minerals in both the spoils and native range
were non-expanding lattice clays.
Thus, the lower amounts of soil
water movement in the spoils were probably not due to the presence
of clay minerals which would expand to a great extent and limit soil
water movement.
Infiltration rates were shown to be significantly different be­
tween all treatments.
Native range had the highest rate of infiltra­
tion followed in order by the topsoiled revegetated, topsoiled nonvegetated and nontopsoiled revegetated spoil treatments.
Native range
had 60-86% greater infiltration rates compared to the spoils.
These
differences in infiltration rates were attributed to the effects of
soil structure, vegetation and topsoiling techniques.
Saturated hydraulic conductivity of disturbed native range
samples was 3.5 times greater than that of the spoil treatments.
This
higher hydraulic conductivity of the native range was attributed to
textural differences between the native range and spoils.
It was
99
conjectured that the saturated hydraulic conductivity of the native
range under field conditions would be even greater due to the pres­
ence of soil structure and lower bulk density.
The time span of this study was too short to show any definite
trends in solute movement in spoils or native range.
Comparison of
chemical analyses data in this thesis with analyses at these same sites
in future years should indicate the existence of solute movement, if
any.
With the exception of potassium and NO^-N, the solute concentra­
tions of the spoils, in general, were not substantially different from
native range.
The spoils contained lower amounts of extractable potas­
sium than native range which could result in potassium deficient vege­
tation on the spoils.
NO^-N concentrations were considerably higher
in spoils than in native range.
The difference was probably due to
the release of fixed NH^-N from the blue shale in the spoils and sub­
sequent conversion to NO^-N and to the application of fertilizer to
the revegetated spoils treatments.
Calculation of exchangeable sodium
percentage (ESP) and sodium adsorption ratio (SAR) indicated the levels
of sodium in both spoils and native range were not sufficiently high
to result in adverse soil physical conditions.
The higher quantities of water movement in the native range, shown
by the water movement model and the in situ water budgets, compared to
the spoil treatments indicate that possibly greater amounts of solute
100
movement into the groundwater would occur from the native range than
from the spoils.
LITERATURE CITED
LITERATURE CITED
1.
Blake, G. R. 1965. Methods of Soil Analysis. Part I. Physical
and Minerological Properties. C. A. Black, ed. ASA Monograph
No. 9. American Society of Agronomy, Inc, Madison, Wise.
pp. 381-333.
2.
Bremner, J . M. 1965a.
Methods of Soil Analysis. Part 2.
Chemical and Microbiological Properties. C. A. Black, ed. ASA
Monograph No. 9. American Society of Agronomy, Inc. Madison,
Wise, pp. 1216-1217.
3.
Bremner, J . M. 1965b. Methods of Soil Analysis. Part 2.
Chemical and Microbiological Properties. C. A. Black, ed. ASA
Monograph No. 9. American Society of Agronomy, Inc. Madison,
Wise. pp. 1191-1198.
4.
Copeland, 0. L. and R.
E . Packer. 1972. Land use aspects of the
energy crisis and western mining. J. Forestry 70: 671-675.
5.
Curtis, W. R. 1973. Moisture and density relations on graded
strip mine spoils In Ecology and Reclamation of Devastated Land.
Volume I. pp. 135-143.
6.
Day, P . R. 1965. Methods of Soil Analysis. Part I. Physical
and Minerological Properties. C . A. Black, ed. ASA Monograph
No. 9. American Society of Agronomy, Inc. Madison, Wise.
pp. 562-564.
7.
Diebold, C. H. 1954. Permeability and intake rates of medium
textured soils in relation to silt content and-degree of compaction
Soil Sci. Soc. Am. Proc. 18:339-343.
8.
Gumbs, F. A. and B. P. Warkenten. 1972. The effect of bulk
density and initial water content on infiltration in clay soil
samples. Soil Sci. Soc. Am. Proc. 36: 720-724.
9.
Hanks, R. J. and F. C. Thorp. 1957. Seedling emergence of wheat,
grain sorghum and soybeans as influenced by soil crust strength
and moisture content. Soil Sci. Soc. Amer. Proc. 21: 357-359.
10.
Hill, J. N . S . and M. E. Sumner. 1967. Effect of bulk density on
moisture characteristics of soils. Soil Sci. 103: 234-238.
11.
Jackson, R. D. 1963. Porosity and soil water diffusivity
relations. Soil Sci. Soc. Am. Proc. 27: 123-126.
103
LITERATURE CITED (CONTrD)
12.
Klute, A. 1965. ' Methods of Soil Analysis, Part I. Physical
and Minerological Properties. C. A. Black, ed, ASA Monograph
No. '9i American Society of Agronomy, Inc. Madison, Wise.
pp. 214-215.
13.
Limstrom,' G. A.
Central States.
14.
Meeuwig, R. 0. 1971. Infiltration and water repellency in
granitic soils. USDA Forest Service Research Paper INT - 111.
15.
National Academy of Sciences. 1974. Rehabilitation Potential
of Western Coal Lands. Ballinger Pub. Co. Cambridge, Mass.
198 pp.
16.
Olsen, S . R., C. V. Cole, F. S . Watanake and L. A. Dean. 1954.
Estimation of available phosphorous in soils by extraction-with
sodium bicarbonate. U. S . Dept. Agr. Circ., 939.
1960. Forestation of strip mined lands in the
U. S . Dept. Agr. Handbook 166.
I
17.
O'Neal, A. M. 1952. A key for evaluating soil permeability
by means of certain field clues. Soil Sci. Soc. Am. Proc.
16: 312-315.
18.
Pratt, P . F. 1965. Methods of Soil Analysis, Part 7. Chemical
and Microbiological Properties. C. A. Black, ed. ASA Monograph
No. 9. American Society of Agronomy, Inc. Madison, Wise.
pp. 1206„ 1033-1034.
19.
Power, J. F. ,. J. J. Bond, W. 0. Willis and F. -M. Sandoval'. 1975
Forms and transformations of nitrogen in Fort Union shales.
Agronomy Abstracts. Am. Soc. Agronomy 1975 Annual Meetings.
p. 32.
20.
Sindelar, B. W., R. L . Hodder and M. E . Majerus. 1973. Surface
manipulation study In Surface Mined Land Reclamation Research
in Montana. Mont. Agr. Exp. Sta. Report 40.
21.
Sisson, J. 3. 1972. Hydraulic Properties of the Gerber Soil.
M.S. Thesis. Montana State University, Bozeman, Montana.
22.
United States Salinity Laboratory staff. 1969. Diagnosis and
Improvement of Saline and Alkali Soils. L. A. Richards, ed.
U. Si Dept. Agr. Handbook 60.
104
LITERATURE CITED (CONT'D)
23.
Verma, T . R. and J. L. Thames. 1975. Rehabilitation of land
disturbed by surface mining coal in Arizona. J. Soil Water
Conser. 30: 129-13,1.
24.
Waldron, L. J., J. L. McMurdie and J. A. Vomocil. 1970.
Hydraulic conductivity of an isotropically compressed soil.
Soil Sci. Soc. Am. Proc. 34: 393-396.
25.
Warkentin, B. P. 1971. Effects of Compaction on Content and
Transmission of Water in Soils In Compaction of Agricultural
Soils. K. K. Barnes, ed. Amer. Soc. Agr. Engin. Michigan.
26.
Yang, S . J. and E . Belong. 1971. Effect of soil water potential
and bulk density on water uptake patterns and resistance to
flow of water in wheat plants. Can. I. Soil Sc!.. 51: 211-220.
APPENDICES
106
Appendix Table I. ■ Soil Conservation Serice classification and
profile description of the Yamac soil series.
The Yamac series consists of deep, well drained soils formed in
alluvium from sedimentary uplands. These soils are nearly level
to strongly sloping and are on fans, footslopes and terraces. The
mean annual precipitation is about 12 inches, and the mean annual
air temperature is about 42°F.
Soil Family:
Fine-loamy, mixed Borollic Camborthids.
Typical Pedon: Yamac loam, grassland.
unless otherwise noted.)
(Colors are for dry soil
Al— 0 to 4 inches, grayish brown (10YR 5/2) loam, very dark gray­
ish brown (10YR 3/2) moist; moderate fine and medium granular
structure; soft, very friable, slightly sticky and slightly plas­
tic; many very fine roots; many fine pores; mildly alkaline (pH
7.4); clear boundary.
(2 to 4 inches thick)
B2— 4 to 11 inches, light olive brown (2.5Y 5/4) loam, olive brown
(2.5Y 5/4) loam, olive brown (2.5Y 4/4) moist; moderate medium
prismatic parting to weak fine and medium blocky structure; slight­
ly hard, very friable, slightly sticky and slightly plastic; many
fine and very fine roots; common fine and very fine pores; mildly
alkaline (pH 7.4); clear boundary. (6 to 12 inches thick)
Clca— 11 to 26 inches, pale olive (5Y 6/3) loam, olive (5Y 5/3)
moist; weak coarse prismatic structure; slightly hard, very fri­
able, slightly sticky and slightly plastic; common fine and very
fine pores; common fine and very fine roots, violently efferves­
cent with common fine soft masses of lime, moderately alkaline
(pH 8.0); gradual boundary.
(20 to 30 inches thick)
C2— 26 to 60 inches, pale olive (5Y 6/3) loam, olive (5Y 5/3)
moist; massive; slightly hard, very friable, slightly sticky
and slightly plastic; few very fine roots; violently efferves­
cent; strongly alkaline (pH 8.5).
Range in Characteristics: The solum is 11 to 20 inches thick.
The 10- to 40-inch control section is loam and has 18 to 27
percent clay, 40 to 55 percent silt plus very fine sand and 15
to 35 percent fine and coarser sand. In most pedons the upper
8 to 12 inches are noncalcareous, but some pedons are calcareous
107
Appendix Table I (con't)
throughout.
46°F.
The mean annual soil temperature ranges from 40° to
The surface layer after mixing to depth of 7 inches has hue of
7.5Y through 2.5Y, value of 5 or 6 dry, and chroma of 2 or 3,
An Al horizon as thick as 4 inches and with value of 5 dry and
3 moist is present in some pedons. Loam and clay loam are the
most common texture phases.
The B2 horizon has hue of 7.5YR through 5Y, value of 5 of 6 dry,
and chroma of 2 through 4. It has moderate to strong prismatic
structure with or without blocky structure. The upper 2 to 4
inches is usually noncalcareous but the lower part has weak to
moderate effervescence in some pedons. Some pedons have B3ca
horizons that have weak and moderate prismatic structure, have
moderate to strong effervescence with few to common masses of
segregated lime, and have hue of 7.5YR through 2.5Y, value of
5 or 6-dry, 4 or 5 moist, and chroma of 2 or 3.
The Cca horizon has few to common masses of segregated lime and
has hue of 5Y or IOYR and value of 6 or 7 dry. In some pedons,
the C horizon below 25 inches has thin strata of sandy loam,
silt loam, or gravelly loam. Below 40 inches in some pedons
there are strata of loamy sand, sand, gravelly loam, or gravel­
ly clay loam.
Geographic Setting: The Yamac soils are nearly level to strongly
sloping and are on fans, footslopes and terraces.. The soils
formed in loam textured alluvium derived locally from adjacent
sedimentary uplands. The climate is cool, dry-semiarid, contin­
ental, with long, cold, dry winters and moist springs and sum­
mers. The mean annual precipitation is 10 to 14 inches, most
of which falls in spring and early summer. Mean annual temper­
ature is 39° to 45°F., mean January temperature 10° to 25 F.
and mean July temperature 60° to 72°F. The (32°F.) growing
season is 105 to 135 days.
Drainage and Permeability: Well drained; slow or medium runoff;
moderate permeability.
Use and Vegetation; These soils are used for both irrigated and
nonirrigated cropland with major crops of small grain, and for
rangeland. The principal vegetation is western wheatgrass, blue-
Appendix Table I (con't)
bunch wheatgrass, prairie junegrass, needle-and-thread grass, green,
needlegrass, bluegrama and 'clubmoss. •
Distribution and Extent: Yamac series is distributed throughout
the eastern plains of Montana and possibly in adjacent states.
It is of moderate extent.
Series Established:
Cascade County, Montana, 1975.
Remarks: Yamac.soils were formerly classified as Brown soils.
National Cooperative Soil Survey
U.S.A.,
109
A p p e n d i x Table 2,
Results of linear r e g r e s s i o n s and c a l c u l a t e d v a lues
of w a t e r m o v e m e n t m o d e l p a r a m e t e r s a an d b for
r e p . I, top s o i l e d n o n v e g e t a t e d t r e a t m e n t , Peabody
Big Sky Mine, summ e r of 1975.
Regression Parameters
Depth (cm)
r
*
2
Model Parameters
slope
intercept
a
b
15
0.883
,-0.0165
1.594
0.3140
0.0165
30
0.945
-0.0154
2.108
0.2604
0.0154
45.
0.939
-0.0131
2.432
0.2406
0.0131
60
0.912
-0.0113
2.667
0.2291
0.0113
75
0.896
-0.0104
2.854
0.2213
0.0104
90
0.892
-0.0101
3.079
0.2308
0.0101
■ 120
0.905
-0.0010
3.314
0.2184
■0.0100
150
0.900
-0.0093
3.492
0.2089
0.0093
180
0.911
-0.0092
3.648
0.2038
0.0092
210
. 0.901
-0.0088
3.780
0.1991
0.0088
240*
0.870
-0.0081
3.900
0.1969
0.0081
270
0.710
-0.0098
4.001
0.1914
0.0098
300
, 0.482
-0.0112
4.088
0.1883
0.0112
330
0.351
-0.0124
4.170
0.1825
0.0124
360 '
0.289
-0.0136
4.246
0.2790
0.0136 ■
3.90
0.245
-0.0148
4.320
0.1765
0.0148
420
0.221
-0.0159
4.388 .
0.1741
0.0159
450
0.194
-0.0164
4.450
0.1721
0.0164
480
0.182
-0.0172
4.508
0.1700
0.0172
d e p t h to w h i c h u n i f o r m ij;
was obtained
HO
A p p e n d i x Table 3.
Results o f linear r e g r e s s i o n s and c a l c u l a t e d v a lues
of w a t e r m o v e m e n t m o d e l p a r a m e t e r s 0. dn d b for
rep 2, top s o i l e d n o n v e g e t a t e d t r e a t m e n t , Peabody
Big Sky Mine, summer o f 1975.
Regression Parameters
Depth (cm)
r
*
2
slope
intercept
Model Parameters
a
b
15
0.653
-0.0172
1.605
0.3168
0.0172
30
0.603
-0.0125
2.119
0.2659
0.0125
45
0.576
-0.0106
2.450 .
0.2473
0.0106
60
0.554
-0.0098
2.698
0.2378
0.0098
75
0.533
-0.0089
2.897
0.2325
0.0089
90
0.532
-0.0084
3.134
0.2457
0.0084
120
0.568
-0.0082
3.374
0.2339
0.0082
150
0.604
-0.0086
3.564
0.2254
0.0086
180
0.663
-0.0097
3.727
0.2201
0.0097
210
. 0.683
-0.0103
3.865
0.2150
0.0103
:240*
0.683
-0.0106
3.975
0.2094
0.0106
270
0.658
-0.0099
.4.073
0.1910
0.0099
300
0.636
-0.0093
4.165
0.2036
0.0093
330
0.602
-0.0086
4.253
0.2027 ■
0..0086
;360
0.583
-0.0082
4.353
0.2057
0.0082
390
0.566
-0.0079
4.429
0.2051
0.0079
420
0.552
. -0.0076
4.501
0.2049
0.0076
depth to which uniform
Ui
m
was obtained
Ill
A p p e n d i x Table 4.
Results of linear r e g r e s s i o n s and c a l c u l a t e d v a l u e s
of water m o v e m e n t m o d e l p a r a m e t e r s 0. and b for
r e p 3, top s oiled n o n v e g e t a t e d treatment, Peabody
Big Sky Mine, summer of 1975.
Regression Parameters
Depth (cm)
r
'
*
2
Model Parameters
slope
intercept
a
b
15
0.828
-0.0098
1.580
0.3152
0.0098
30
0.828
-0.0069
2.089 .
0.2605
0.0069
45
0.776
-0.0063
2.427
0.2457
0.0063
60
0.745
-0.0055
2.673
0.2360
0.0055
75 :
0.734
-0.0052
2.870
■■ 0.2300
0.0052
90
0.722
-0.0048
3.106
0.2428
0.0048
120
0.710
t O.OOSO
3.351
0.2321
0.0050
150
0.726
-0.0048
3.550
0.2266 '
0.0048
180
0. 722
-0.0048
3.711
0.2217
0.0048
210*
0.710
. -0.0047
3.847
0.2176
0.0047
240
0.686
-0.0044 .
3.964
0.2142
0.0044
270
0.692
-0.0044
4.067
0.2110
0.0044
300
0.692
-0.0042
4.160
0.2085
0.0042
330
0.692
-0.0040
4.244
0.2063
0.0040
360
0.678
-0.0038
4.320
0.2042
0.0038
390
0.664
-0.0037
4.391
0.2025
0.0037
420
'0.650
-0.0035
4.458
0.2012
0.0035
450
0.656
-0.0035
4.520
. 0.1998
0.0035
d e p t h to w h i c h u n i f o r m
was o b t a i n e d
112
A p p e n d i x Table 5.
Results of linear r e g r e s s i o n s a n d c a l c u l a t e d v a lues
of w a t e r m o v e m e n t m o d e l p a r a m e t e r s CL a nd b for
rep I, t o p s o i l e d r e v e g e t a t e d treatment, Peabody
Big Sky Mine; summer of 1975.
Regression Parameters
*
Model Parameters
.2
r
slope
intercept
15
0.790
-0.0191
1.517
0.2886
0.0191
30
0.728
-0.0158
2.036
0.2420
0.0158
45
0.678
-0.0153
2.383
0.2272
0.0153
60
0.633
-0.0153
2.643
0.2199
0.0153
75
0.603
-0.0144
2.856
0.2179
0.0144
90
0.554
-0.0118
3.118
0.2382
0.0118
120*
0.426
-0.0091
3.385
0.2355
0.0091
150
0.248
-0.0058
3.578
0.2319
0.0058
180
0.105
-0.0032
3.732
0.2282
0.0032
210
0.014
-0.0010
3.861
0.2250
Q.0010
240
0.002
-0.0003
3.981
0.2228
0.0003
270
0.001
-0.0003
4.079
0.2185
0.0003
300 .
0.0001
-0.0001
4.162
0.2139
0.0001
330
0.003
-0.0004
4.255
0.2130
0.0004
360
0.005
-0.0005
4.328
0.2099
0.0005
390
0 .008
-0.0006
4.402
0.2085
0.0006
420
0.009
-0.0007
4.471
0.2073
0.0007
450
0.014
-0.0008
4.534 •
0.2059
0. 0008
depth to which uniform
lb
m
was obtained
a
b
n v3
A p p e n d i x Table 6.
Depth (cm)
*
Results of linear regr e s s i o n s and calcul a t e d valu e s
of w ater m o v e m e n t m o d e l p a r a m e t e r s <X a nd b for
rep 2, top s o i l e d r e v e g e t a t e d treatment, Peabody
Big Sky Mine, summer of 1975.
Regression Parameters
Model Parameters
r2 '
slope
•intercept
a
b
15
0.852
-0.0157
1.571
0.3074
0.0157
30
0.846
-0.0127
2.070
0.2530
0.0127
45
0.834
-0.0099
2.418
0.2402
0.0099
60
0.855
-0.0115
2,679
0.2318
0.0115
75
0.849
-0.0119
2.876
0.2248
0.0119
90
0.841
-0.0113
3.125
0.2403
0.0113
120
0.797
-0.0109
3.384
0.2333
0.0109
150
.0.754
-0.0084
3.606
0.2353
0.0084
180*
0.732
-0.0078
3.809
0.2406
0.0078
210
0.575
-0.0064
3.947
0.2383
0.0064
. 240
0.488
-0.0050
4.060
0.2350
0.0053
270
0.438
-0.0042
4.157
0.2311
0.0042
300
0.409
-0.0039
4.246
0.2276
0.0039
330
0.409
-0.0032
4.331
0.2261
0.0032
360
0.344
-0.0031
4.406
0.2235
0.0031
390
0.390
-0.0036
4.487
0.2230
0.0036
420
0.369
-0.0034
4.549
0.2205
0.0034
450
0.250
-0.0561
1.773.
0.0093
0,.0561
480
0.298
-0.0451
1.914
0.0107
0.0451
d e p t h to w h i c h u n i f o r m
w as o b t a i n e d
•
I
114
A p p e n d i x Table 7.
Results o f line a r r e g r e s s i o n s and c a l c u l a t e d v a l u e s
of w a t e r m o v e m e n t m o d e l p a r a m e t e r s CL and 6 for
rep 3, t o p s o i l e d r e v e g e t a t e d treatment, Peabody
Big Sky Mine, summer of 1975
Regression Parameters.
Depth (cm)
r
*
2
slope
intercept
Model Parameters
a
b
15
0.692
-0.0283
1.520
0.2821
0.0283
30
0.738
-0.-0187
2.065
0.2465
0.0187 .
45
0.468
-0.0080
2.385
0.2341
0.0080
60*
0.110
-0.0021
2.630.
0.2292
0.0021
75
0.0001
-0.00004
2.823
0.2243
0.00004
. 90
0.299
-0.0020
3.051
0.2327.
0.0020
120
0.372
-0.0018
3.299
0.2238
0.0018
150
0.185
-0.0011
3.518
0.2235
0.0011
180
0.003
-0.0001
3.693
0.2230
0.0001
210
0.049
-0.0006
3.836
0.2200
0.0006
240
0.068
-0.0006
3.970
0.2200
0.0006
270
0.311
-0.0016
4.101
0.2217
0.0016
300
0.327
-0.0018
4.217
0.2238
0.0018
330
0.394
-0.0022
4.311
0.2229
0.0022
depth to which uniform ij^ was obtained
115
A p p e n d i x Table 8.
Results o f linear regre s s i o n s a n d c a l c u l a t e d v a l u e s
of w a t e r m o v e m e n t m o d e l p a r a m e t e r s a. a nd b for
rep I, n o n t o p s o i l e d r e v e g e t a t e d treatment, Pea b o d y
B i g Sky Mine, summer of 1975
x
Regression Parameters
Depth (cm)
r
*
2
Model Parameters
slope
intercept
a
b
15
0.760
-0.0126
1.602
0.3199
0.0126
30
0.722
-0.0116
2.105
. 0.2629
0.0116
45
0.679
-0.0100
2.438 .
0.2449
0.0110
60*
0.576
-0.0058
2.661
0.2329
0.0058
75
0.492
-0.0034
. 2.834
0.2234
0.0034
90 ■
0.118
-0.0011
3.045
. 0.2323
0.0011
120
0.164
-0.0013
3.279
0.2199
0.0013
150
0.244
-0.0018
3.441
0.2063
0.0018
180
0.180
-0.0014
3.590
0.1998
0.0014
210
0.200
-0.0015
3.721
0.1951
0.0015
240
0.147
-0.0013
3.829
0.1904
0.0013
270
0.039
-0.0006
3.934 .
0.1887
0.0006
300
0.031
-0.0005
4.037
0.1883
0.0005
depth to which uniform
was obtained
116
Appendix Table 9.
Results of linear regression and calculated values
of water movement model parameters a and b for
rep 2, nontopsoiled revegetated treatment, Peabody
Big Sky Mine, summer of 1975
Regression Parameters
Depth (cm)
2
V
*
slope
intercept
Model Parameters
a
b
15
0.868
-0.0145
1.517
0.2921
0.0145
30
0,848
-0.0163
1.989
0.2316
0.0163
45
0.827
-0.0137
2.269
0.2040
0.0137
60
0.790
-0.0106
2.475
0.1896
0.0106
75
0.705
-0.0091
2.660
0.1833
0.0091
90
0.551
-0.0092
2.921
0.1979
0.0092
120
0.404
-0.0094
3.227
0.2008
0.0094
150
0.545
-0.0078
3.457
0.2033
0.0078
180
0. 660
-0.0062
3.630
0.2029
0.0062
210
0.700
-0.0052
3.772
0.2013
0.0052
240
0.701
-0.0058
3.902
0.1998
0.0058
270*
0.834
-0.0052
4.002
0.1968
0.0052
300
0.835
-0.0056
4.094
0.1934
0.0056
330
0.819
-0.0058
4.182
0.1919
0.0058
360
0.856
-0.0054
4.257
0.1899
0.0054
390
0.846
-0.0059
4.331
0.1882
0.0059 '
420
0.862
-0.0058
4.402
0.1876
0.0058
450
0.860
-0.0057
4.467
0.1869
0.0057.
480
0.861
-0.0054
4.528
0.1865
0.0054
d e p t h to. w h i c h u n i f o r m ij;
was o b t a i n e d
117
A p p e n d i x Table 10.
Results o f linear r e g r e s s i o n s and c a l c u l a t e d
v a lues of w a t e r m o v e m e n t m o d e l p a r a m e t e r s a a nd b
for rep 3, n o n t o p s o i l e d r e v e g e t a t e d treatment,
P e a b o d y Big Sky Mine, summer of 1975.
Regression Parameters
Depth (cm)
r
*
2
Model Parameters
slope
intercept
a
b
15
0.761
-0.00280
1.594
0.3043
0.0280
30
0.712
-0.0272
2.109
0.2502
'0.0272
45
0.636
-0.0255
2.437
0.2307
0.0255
60*
0.533
-0.0230
2.672
0.2195
0.0230
75
0.407
-0.0197
2.853
0.2123
0.0197
90
.0.301
-0.0165
3.070
0.2222
0.0165
120
0.268
-0.0152
3.299
0.2099
0.0152
150
0.261
-0.0146
3.471
0.1992
0.0146
180
0.250
-0.0141
3.625
0.1938
0.0141
210
0.250
-0.0141
3.768
0.1912
0.0141
240
0.253
-0.142
3.894
0.1893
0.0142
270
0.259
-0.0142
3.998
0.1864
0.0142
300
0.257
-0.0142
4.099
0.1853
0.0142
330
0.257
-0.0142
4.191
0.1844
0.0142
360
0.261
-0.0143
4.273
0.1832
0.0143
390
0.260
-0.0143
4.348
0.1821
0.0143
420
0.260
-0.0143
4.420
0.1815
0.0143
450
' 0.263
-0.0143
4.483
0.1802
0.0143
480
0.614
-0.1080
. 4.119
0.0658
0.0808
depth to which uniform
ib
m
was obtained
118
A p p e n d i x Table 11.
R e s u l t s of linear r e g r e s s i o n s a n d calcul a t e d
v a l u e s of w a t e r m o v e m e n t m o d e l p a r a m e t e r s a and b
for r e p I, n a t i v e range treatment, Peab o d y Big
Sky Mine, summer o f 1975
Regression Parameters
Depth (cm)
r
*
2
Model Parameters
slope
intercept
a
b
15
0.743
-0.0201
1.504
0.2841
0.0201
30
0.848
-0.0177
2.042
0.2419
0.0177
45
0.894
' -0.0168
2.403
0.2305
0.0168
60
0.929
-0.0158
2.669
0.2254
0.0158
75
0.935
-0.0148
2.866
0.2198
0.0148
. 90*
0.912
-0.0143
3.104
0.2321
0.0143
120
0.361
-0.0102
3.347
0.2256
0.0102
150
0.304
-0.0105
3.540
0.2180
0.0105
180
0. 328
-0.0095
3.707
0.2154
0.0095
depth to which uniform lb was obtained
■
m
■
119
A p p e n d i x Table 12.
Results o f line a r r e g r e s s i o n s a n d c alculated
v alues of w a t e r m o v e m e n t m o d e l p a r a m e t e r s a a nd b
for rep 2, n a t i v e range treatment, Peab o d y Big
Sky Mine, summer of 1975.
Regression Parameters
Depth (cm)
r
*
2
Model Parameters
slope
intercept
a
b
15
0.907
-0.0197
1.580
0.3068
0.0197
30
0.879
-0.0198
2.103
0.2560
0.0189
45
0.836
-0.0170
2.436
0.2380
0.0170
60
0.816
-0.0158
2.680
0.2279
0.0158
75
0.802
-0.0163
2.879
0.2212
0.0163
90*
0.805
-0.0170
' 3.119
0.2329
0.0170
120
0.796
-0.0144
3.363
0.2246
0.0144
150
0.761
-0.0125
3.556
0.2194
0.0125
180'
0.753
-0.0106
3.704
0.2135
0.0106
depth to which uniform ijj was obtained
120
A p p e n d i x Table 13.
R e sults of linear regressions a nd c a l c u l a t e d
v a l u e s of w a t e r m o v e m e n t model p a r a m e t e r s CL and b
v for rep 3, nati v e r a n g e treatment, P e a b o d y Big
Sky M i n e , summer of 1975
Regression Parameters
Depth (cm)
r
*
2
slope
intercept
Model Parameters
a
b
15
0. 968
-0.0384
1.506
0.2709
0.0384
30
0.968
-0.0354
2.054
0.2284
0.0354
45
0.965
-0.0291
2.401
0.2195
0.0291
60
0.950
-0.0270
2.658
0.2129
0.0270
75
0.942
-0.0270
2.856
0.2064
0.0270
90
0.938
-0.0281
3.091
0.2154
0.0281
120
0.920
-0.0289
3.340
0.2048
0.0289
150*
0.901
-0.0274
3.543
0.2009
0.0274
180
0.879
-0.0252
3.708
0.1987
0.0252
depth to which uniform
^
Tp
m
■
was obtained
Appendix Table 14.
460
Monthly soil profile water balance to the ISO and
cm depths for rep I, topsoil nonvegetated spoils treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value
indicates a gain of water in the profile. AJl data are presented in centimeters.
Jan
Feb
Mar
Apr
* y
Period
Total
Jan. '75A p r . '76
0.00
1.96
2.00
4.98
6.50
62.06
-2.99 -3.13 -2.60 -3.76
-49.41
1976
1975
Mar
Apr
Nmy
Jun
Jul
Al1
Sep
Oct
Precipitation, PPT
2.30
2.00
2.50
5.60
8.10
7.40
4.40
S-SOt
0.00
2.00
3.60
2.60
46.31
Eripo.
transpiration, ET
-0.81
0.00
0.00
-0.70
-3.20
-1.50
0.00
0.00
-0.01
2.29
Runoff, R O 2
.
0.00
-2.99* -3.13* -2.60* -3.76
0.00
0.00
0.00
0.00
-6.93 -10.10
0.00
0.00
0.00
0.00
0.00
Water flow, WF
460 cm
Change soil water
content ASWC
—
—
Water flow, WF
„
„
Change soil wat er
content, ASWC
—
—
—
—
—
—
—
—
—
—
0
moisture reading for November not available.
*
evapotranspiration measured by weighing lysimeter method
2
runoff was not measured but assieed to be zero.
^
indicates amount of water which entered profile during flooding.
covered with plastic.
—
—
—
--
0.00
0.00
—
1.49
3.19 -1.57 -3.43
—
—
0.00
0.00
0.00
0.00
3.07
0.39
0.40
3.39
--
1.01
2.16 -2.70 -1.25
—
—
-6.76
0.45
1.35
3.58
—
5.89
6.10 -5.24 -8.27
--
—
-6.76
1.75
1.75
4.68
—
5.41
-.07 -6.37 -6.09
—
--
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
(see m e t h o d o l o g y ) .
Zero values for PPT and ET following this represents the period the plot was
ET values for January to May, 1975, not measured but assumed to equal the measured ET values for January to May, 1976.
data not available due to equipment malfunction.
0.00
121
ISO cm
S
Feb
i
Jan
Nov0
Dec
Yearly
Total
a
S
Profile
Hydrologic Component
Depth
Appendix Table 15.
Monthly soil profile water balance to the 150 and 420 cm depths for rep 2, topsoiled r.onvegetated spoils treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value indicates
a gain of water in the profile. All data are presented in centimeters.
I
I
Precipitation, PPT
Evapoi
t r a n s p i r a t i o n , ET
Punoff, PO2
2.00
Mar
Apr
2.50
5.60
-0.81* -2.99* -3.13* -2.8*
May
8.10
Jun
5.40*
Jul
Aug
Sep
Oct
0.00
0.00
1.50
2.00
3.60
Nov0
-3.76*
0.00
0.00
0.00
-2.30
-0.70
-3.20
Dec
I Total
J*n
Feb
Mar
Apr
2.60
35.60
0.33
1.96
2.00
4.98
May Apr.
'76
6.50
44.87
-1.50 -21 .19 -0.81 -2.99 -3.11 -2. 80 -3.76
-30.92
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
- 8.47
0.00
-0.18
3.50
0.89
-2.52
-0.16
-7.45
-2.84
-0.10
0.50
-0.49
0.41
1.21 - 7 . 2 2
1.25
3.84 -1.80 -4.54
„
1.31
2.51
0.26
0.28
4.18
-2.05
-2.84
-0.10
-0.30
0.81
0.81
2.31
7.19
0.77
2.81 -2.93 -2.36
-
Wat er flew, WT
1.68
8.08
2.33
-1.94
2.49 -11.97
.13
-0.4C
0.00
0.80
1.80
1.35 - 2.41
2.43
8.31 -4. 16 -9. 44
- 5.27
C h a n g e soil w a t e r
c o n t e n t , ASWC
3.17
7.09
1.70
0.86
-".13
-0.40
-0.80
2.10
2.20
2.95
1.95
7.28 -5.29 -7.26
8.68
6.83
-6.57
0
moisture reading for November not available.
1
eva potra nspir atio n mea sured b y wei ghing lysimeter me t h o d (see m e t h o d o l o g y ) .
12.00
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
r u n o f f w a s not m e a s u r e d but a s s u m e d to b e zero.
indicates amount of water which entered profile during flooding.
covered with plastic.
Zero val ues for PPT and ET following this rep resen ts the period the plot was
E T v a l u e s f o r J a n u a r y to M ay , 197 5, n o t m e a s u r e d b u t a s s u m e d t o e q u a l t h e m e a s u r e d E T v a l u e s f o r J a n u a r y to May , 1976.
d at a net a v a l Iao Ie due to e q u i p m e n t mal fun c t i o n .
5.48
122
4 20 ca
2.30
Feb
Period
Total
1976
Cha nge soil wat er
content ASWC
W a t e r flow, WF
ISO cm
I
1975
Proflie
,Hydrclogic Component ; Jan
Depth
Appendix Table 16.
Monthly soil profile water balance to the 150 and 450 cm depths for rep 3, topsoiled nonvegetated spoils treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value indicates
a gain of water in the profile. All data are presented in centimeters.
1975
Profile
Hydrologic Component
Depth
Precipitation, PPT
Evapoi
transpiration, ET
Runoff, RO^
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2.30
2.00
2.50
5.60
8.10
7.40
4.32+
0.00
0.00
2.00
3.60
2.60
0.00
0.00
0.00
-0.70
-3.20
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-0.81* -2.99* -3.13* -2.80* -3.76* -6.93
Yearly
Total
Feb
Mar
Apr
40.42
0.33
1.96
2.00
4.98
Ma y Apr.
6.50
49.69
-1. 50 -25.82 -0.81 -2.99 -3.13 -2. 80 -3.76
-35.55
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.37 - 8.29
1.14
3.99 -2.42 -4.35
--
- 9.93
0.00
-0.59
3.32
1.49
-2.27
0.25
-6.34
-3.35
-1.08
-0.17
-0.91
-0.01
0.90
2.33
0.86
0.53
4.59
-5.87
0.97
-1.08
-0.17
0.39
0.39
2.47
6.31
0.66
2.96 -3.55 -2.17
—
Wa t e r flow, WF
1.31
7.46
1.53
-1.78
4.04 -14.24
-2.13
-2.07
-0.39
-0.02
0.88
3.98 - 1.43
2.46
8.71 -5.42- 10.51
--
Cha nge soil water
content, ASWC
2.80
6.47
0.90
1.02
8.38 -13.77
2.19
-2.07
-0.39
1.28
1.28
5.08
15.17
1.98
7.68 -6.55 -8.33
—
°
moisture reading for November not available.
1
eva potra nspir alio n mea s u r e d by wei g h i n g lysimeter met hod (see methodology).
^
runoff was not measured but assumed to be zero.
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
indicates amount of water which entered profile during flooding.
covered with plastic.
Zero values for PPT and ET following this represents the period the plot was
Et values for January to May, 1975, not measured but assumed to equal the measured ET values for January to May, 1976.
data not available due to equipment malfunction.
'76
4.21
- 6.19
7.95
123
450 cm
Feb
Change soil water
content, ASWC
Wa t e r flow, WF
150 cm
Jan
Period
Total
1976
I
j Jan
Appendix Table 17.
Monthly soil profile water balance to the 150 and 450 ca depths for rep I, topsoiled revegetated spoils treatment, Peabody Big
>line, January, 1975 to April, 1976. A negative value indicates a loss of water f-om the profile and a positive value
indicates a gain of water in the profile. All data are presented in centimeters.
I
i___
Profile
Hyd rologic Component;
Depth
Precipitation, PPT
Evapo,
transpiration, E T 1
Runoff, RO^
450 cm
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
z.so
2.00
2.50
5.60
8.10
5.74*
0.00
0.00
0.00
2.00
5.60
Nov0
Dec
Yearly
Total
Jan
Feb
Mar
Apr
2.60
34.44
0.33
1.96
2.00
4.98
'76
6.50
43.71
-0.81 -2. 99 -3.13 -2. 80 -3. 76
-28.62
0.00
0.00
0.00
0.00
-0.70
-3.20
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-3.29
1.40
3:6
0.57
--
- 7.09
6.52 -3.77
0.37
2.13
2.75
--
8.00
-0.60 - 3.56
-8.6"
2.4-
".'I
2.52
--
0.47
11.99
9.15
1.44
6.58
4.70
--
15.56
-0.81* -2.99* -3.13* -2.80* -3.76*
-1.50 -18.89
N a y Apr.
Water flow, WT
-2.17
0.12
2.43
-1.90
-3.34
-4.88
-0.02
-0.82
-1.62
0.75
1.66
0.76 - 9.03
Cha nge soil water
content, ASWC
-C.68
-0.87
1.80
0.90
1.00
0.86
-0.02
-0.82
-1.62
2.05
2.06
1.86
W a t e r flow, WT
-2.57
-2.28
1.92
-1.12
-5.87
-6.44
-0.13
0.30
-2.43
7.38
8.28
C ha nge soil wat er
content, ASWC
- 1 .08
-3.27
1.29
1.68
-1.53
-0.70
- 0.13
0.30
-2.43
8.68
8.68
0
moisture rea ding for Nov ember not available.
*
e v a p o t r a n s p i r a t i o n m e a s u r e d b y w e i g h i n g l y s i m e t e r m e t h o d (see m e t h o d o l o g y ) ,
0.50
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o Z e c e m b e r I b y 2.
run off was not m e a s u r e d but a s s umed to be zero.
indicates amount of water which entered profile during flooding.
covered with plastic.
Zer o v a l u e s for P PT and ET fol lowin g t h i s rep resen ts the per iod the plot was
E T v a l u e s f o r J a n u a r y tc May , 197 5, n o t m e a s u r e d but a s s u m e d to e q u a l t h e m e a s u r e d E T v a l u e s f o r J a n u a r y t o M ay , 19'6.
d a t a not a v a i l a b l e d u e t o e q u i p m e n t ma l f u n c t i o n .
124
150 cm
Period
Total
1976
1975
Appendix Table 18.
Monthly soil profile water balance to the 150 and 480 cm depths for rep 2, topsoiled revegetated spoils treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value
indicates a gain of water in the profile. All data are presented in centimeters
Precipitation, PPT
Evapoj
tra nspir ation , ET
480 cm
Feb
Mar
Apr
Msy
Jun
Jul
Aug
Sep
Oct
Nov0
2.30
2.00
2.50
5.60
8.10
8.34+
0.00
0.00
0.00
2.00
3.60
0.00
0.00
0.00
0.00
-0.70
-3.20
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Wa t e r flow, WF
-4.15
1.79
1.12
-0.91
-3.02
-5.10
-1.91
-0.16
-0.01
0.74
Change soil water
content, ASWC
-2.66
0.80
0.49
1.89
1.32
3.24
-1.91
-0.16
-0.01
Water flow, WF
-7.98
6.08
1.12
-4.22
-7.99
-7.14
-1.26
-0.53
Cha nge soil water
content, ASWC
-6.49
5.09
0.49
-1.42
-3.65
1.20
-1.26
-0.53
-0.81* -2.99* -3.13* -2.80* -3.76*
°
moisture reading for November not available.
*
evapotranspiratior. m e a s u r e d by w e i ghing lys imete r m et hod (see m e t h o d o l o g y ) .
“
runoff was not measured but assumed to be zero.
Dec I Total
Jan
Feb
Mar
Apr
37.04
0.33
1.96
2.00
4.98
2.60
6.50
46.31
-1. 50 -18 .89 -0.81 -2. 99 -3. 13 -2.80 -3. 76
-28.62
0.00
0.00
0.00
1.64
-1.79 -11.76
-3.48
1.56 3.07
2.04
2.04
-0.69
6.39
-3.96
0.53
1.94
3.46
-0.34
5.09
5.99
-2.44 -15.62- 0.93
3.03
8.27
4.46
-0.34
6.39
6.39
-1.34
4.53- 1.41
2.00
7.14
6.64
0.00
0.00
0.00
0.00
1.28
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f c r O c t o b e r I t o D e c e m b e r I b y 2.
indicates amount of water which entered profile during flooding.
covered with plastic.
Zero values for PPT and ET following this represents the period the plot was
values for January to '-lay, 1975, not measured but assumed to equal the measured ET values for January to May, 1976.
data not available due to equipment malfunction.
0.00
- 9.33
—
8.36
- 8.79
--
8.90
125
150 cm
Jan
0.00
Runoff, RO^
Period
Total
Jan . 1^SM a y A p r . '76
1976
1975
Profile
Hydrologic Component
Depth
Appendix Table 19.
Monthly soil profile water balance to the 150 and 330 cm depths for rep 3, topsoiled revegetated spoils treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value
indicates a gain of water in the profile. All data are presented in centimeters.
Profile
Hydrologic Component
Depth
Precipitation, PPT
Evapotra nspir ation , ET
350 cm
2.30
Feb
2.0
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov0
2.50
5.60
8.10
7.40
4.84f
0.00
0.00
2.00
5.60
Dec
2.60
'Ieaxly
Total
40.94
Jan
Feb
Mar
Apr
0.33
1.96
2.00
4.98
H ay Apr.
'76
6.50
50.21
- 1 . 5 0 -25 .82 -0.81 -2. 99 - 3 . 1 3 - 2 . 8 0 -3. 76
-35.55
0.00
0.00
0.00
-0.70
-3.20
Runoff, RO^
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Water
4.00
1.99
1.80
-3.65
-2.87
-4.50
-3.19
-0.16
-0.19
0.60
1.50
0.24 -12.34
-3.26
1.47
3.37
1.05
——
- 9.80
-2.51
1.00
1.17
-0.85
1.47
-4.03
1.65
-0.16
-0.19
1.90
1.90
1.34
2.69 -3.74
0.44
2.24
3.23
--
4.86
Wat er flow, WF
3.24
3.82
1.78
-4.33
-6.58
-5.88
-3.51
-0.85
-1.04
3.01
3.91
0.28 -12.63
-6.86
2.34
6.73
3.24
--
- 7.18
Cha nge soil water
content, ASWC
1.75
2.83
1.15
-1.53
-2.24
-5.41
1.33
-0.85
-1.04
4.31
4.31
1.38
2.49
".34
1.31
5.60
5.42
—
low, WF
Change soil water
content, ASWC
-0.81* -2.99* -3.13* -2.80* -3.76* -6.93
0
moisture reading for November not available.
*
eva potra nspir atio n mea s u r e d by wei ghing lys imete r met hod (see methodology).
~
runoff was not measured but assumed to be zero.
L S Y tC
s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g I S K C f o r O c t o b e r I t o D e c e m b e r I b y 2.
indicates amount of water which entered profile during flooding.
covered with plastic.
Zero values for PFT and ET following this represents the period the plot was
values for January to May, 1975, not measured but assumed to equal the measured ET values for January to May, 1976.
data not available due to equipment malfunction.
".48
126
150 cm
Jan
Period
Total
1976
1975
Appendix Table 20.
Monthly soil profile water balance to the 150 and 300 cm depths for rep I, nontopsoiled revegetated spoils treatment, Peabody Big
Sky Mire, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value indicates
a gain of water in the profile. All data are presented in centimeters.
ProfiIe I
Depth
.Hydrologic Component
Precipitation, PPT
Evapci
transpiration, ET
R u n o f f , RO*"
Cha nge soil wa t e r
con tent, ASWC
Wat er flow, WF
300 cm
Cha nge soil water
c o n t e n t , ASWC
2.30
2.00
5.60
2.50
8.10
7.40
4.40
-0.81* -2.99* -3.13* -2.80* -3.76* -6.93 -10.10
0.00
2.00
3.60
0.00
0.00
-0.70
-3.20
2.60
45.42
0.33
Apr
1.96
2.00 4.98
6 . SO
54.69
-1.50 -35.92 -0.81 -2.99 -3.13 -2.80 -3.76
-45.65
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-0.80
1.37
-0.17
-0.84
-7.80
-1.39
4.11
-0.82
-0.44
0.38
1.28
4.42 - 0.70 -5.29
0.69
0.38
-0.80
1.96
-3.46
-0.92
-1.59
4.10
-0.44
1.68
1.68
5.52
8.80 -5.77
1.82 -3.10
-1.24
1.37
-0.92
0.17
-9.70
-1.46
4.34
-0.31
-0.52
1.88
2."9
5.54
1.94 -8.97
4.29 -3.27 -1.87
6.64
11.44 -9.45
0.25
0.38
2.97
-1.55
-5.36
-0.99
-1.36
0
moi sture rea ding for Nov ember not available.
1
evapotra nspir atio n mea sured by wei ghing lys imete r me t h o d (see methodology).
*■
4.92*
4.61
-0.52
3.18
3.13
Period
Total
Jan . '75M a y A p r . '76
0.00
0.00
0.00
0.00
0.00
0.00
2.85 -1.97 -1.56
3.26 -4.40
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g I S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
run off was not m e a sured but a ss umed to be zero.
indicates amount of water which entered profile during flooding.
covered wit h plastic.
Zero val ues for PPT and ET following this rep resen ts the period the plot was
v a l u e s f o r J a n u a r y to May , 1975, not m e a s u r e d b u t a s s u m e d to equ al t h e m e a s u r e d E T v a l u e s f o r J a n u a r y to May , 1976.
data not available due to equipment malfunction.
- 6.67
0.62
0.31
0.00
2.37
-**
- T 88
1.16
127
Wat er flow, WF
150 cm
--- 5- - - - - - Y e a r l y Sov
Dec ! Total
Appendix Table 21.
Monthly soil profile water balance to the 150 and 480 an depths for rep 2, nontopsoiled revegetated spoils treatment, Peabody Big
Sky Mire, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value
indicates a gain of water in the profile. All data are presented in centimeters.
T™"
•
Profile
Hydrologic Component
Depth
0.00
2.00
3.60
0.00
0.00
-0.70
-3.20
0.00
0.00
0.00
0.00
0.00
-1.17
0.49
1.39
2.59
--2 . 9 2
2.31 -2.69 -1.84
-1.17
1.79
1.79
3.69
--3 . 4 0
1.28 -3.82
Water flow, WF
4.24
5.14
7.12
—
10.8"
5.58 -5.39 -2.99
Change soil wat er
content, ASWC
5.54
.5.54
8.22
—
11.35
4.55 -'.66 -0.81
Jan
Feb
Mar
Apr
Hsy
Jun
Jul
Aug
2.30
2.00
2.50
5.60
8.10
7.40
4.40
-0.81* -2.99* -3.13* -2.80* -3.76* -6.93 -10.10
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Water flow, WF
Change soil water
content, ASWC
--
--
—
—
—
—
—
0
moisture reading for November not available.
1
eva potra nspir atio n m e a s u r e d by wei ghing lysimeter met hod (see m e t h o d o l o g y ) .
—
2.60
49.93
0.33
Feb
Mar
Apr
1.96
2.00
4.98
6.50
59.20
-1.50 -35.92 -0.81 -2.99 -3.13 -2.80 -3.76
-45.65
0.00
0.00
0.00 0.00
0.00
0.00
0.34
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
*■ runoff was not measured but assumed to be zero.
indicates amount of water which entered profile during flooding.
covered with plastic.
Zero values for PPT and ET following this represents the period the plot was
values for January to May, 1975, not measured but assumed to equal the measured ET values for January to May, 1976.
data not available due to equipment malfunction.
0.00
--
--
—
--
128
9.43*
Runoff, RO^
4 8 0 cm
Dec
Oct
Evapo1
transpiration, ET
150 cm
Nov0
Yearly
Total
Sep
Precipitation, PPT
Period
Total
Jan. '75H a y A p r . '76
1976
1975
Appendix Table 22.
Monthly soil profile water balance to the 150 and 480 cm depths for rep 3, nontopsoiled revegetated spoils treatment, Peabody Big
Sky Mine, January, 1975 to April, 1976. A negative value indicates a loss of water from the profile and a positive value
indicates a gain of water in the profile. All data are presented in centimeters.
150 cm
4 8 0 cm
Nov0
Dec
Yearly
Total
Jan
Feb
Mar
Apr
2.60
37.06
0.33
1.96
2.00
4.98
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Precipitation, PPT
2.30
2.00
2.50
5.60
8.10
a. S e t
0.00
0.00
0.00
2.00
3.60
Evapo,
transpiration, ET
0.81* -2.99* -3.13* -2.80* -3.76*
0.00
0.00
0.00
0.00
-0.70
-3.20
0.00
0.00
0.00
0.00
0.00
0.00
0.00
46.33
-1.50 -18.89 -0.81 -2.99 -3.13 -2.80 -3.76
-26.82
0.00
0.00
0.00
0.00
0.00
0.00
Wat er flow, WF
-2.76
3.30
1.46
-3.81
-6.38
-4.11
-1.26
-0.43
-0.21
0.52
1.43
3.76
8.49
5.02
3.52 -3.03 -1.92
Change soil water
content, ASWC
-1.27
2.31
0.83
-1.01
-2.04
4.25
-1.26
-0.43
-0.21
1.82
1.83
4.86
9.68
5.50
2.49 -4.16
Water flow, WF
3.87
5.38
-0.47
-1.59 -12.46
0.17
-3.75
-1.17
-0.56
4.46
5.36
8.90
Change soil water
content, ASWC
2.38
4.59
-1.10
-8.12
8.53
-3.75
-1.17
-0.56
5.76
5.76
10.00
1.21
0.00
0.00
6.50
0.00
Runoff, R O 2
Period
Total
J an . '75M a y A p r . '76
1976
1975
Profile
Hydrologic Component
Depth
0
moisture reading for November not available.
1
ev a p o t r a n s p i r a t i o n m e a s u r e d b y w e i g h i n g lys imete r m e t h o d (see met hodol ogy).
0.00
0.00
—
2.77
0.40-1 5.96
9.69 -7.73 -2.87
—
-16.47
18.57-1 6.44
8.66 -8.86 -0.69
—
1.24
2
r u n o f f w a s not m e a s u r e d b u t a s s u m e d t o be zero.
values for Jan u a r y to May,
Zero val ues for PPT and ET fol lowin g this rep resen ts the period the plot was
1975, n o t m e a s u r e d b u t a s s u m e d t o e q u a l the m e a s u r e d E T v a l u e s for J a n u a r y t o M a y , 1976.
data not available due to equipment malfunction.
-14.94
0.26
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
indicates amount of water which entered profile during flooding.
covered with plastic.
0.00
Appendix Table 23.
Monthly soil profile water balance to the 150 cm depth for rep I, native range treatment, Peabody Big Sky Mine, January, 1975
to April, 1976. A negative value indicates a loss of water from the profile and a positive value indicates a gain of water in
the profile. All data are presented in centimeters.
Jar.
Feb
Mar
Apr
May
Period
Total
J a n . '75
Apr . '76
0.33
1.96
2.00
4.98
6.50
53.36
-0.81 -2.99 -3.13 -2.80 -3.76
-35.55
1975
Hydrologic Component
Precipitation, PPT
Evapo,
transpiration, ET
Runoff, RO2
W a t e r flo w, WF
Dec
3.60
2.60
44.09
-0.70
-3.20
-1.50
-25.82
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
2.30
2.00
2.50
5.60
8.10
7.40
7.99*
0.00
0.00
2.00
0.00
0.00
0.00
-0.61* -2.99* -3.13* -2.80* -3.76* -6.93
Nov0
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-0.55
0.60
0.94
-0.71
-6.09
-2.53
-1.47
-2.63
-0.58
-0.14
0.77
0.14
-12.25
-1.23
1.33
0.95 -3.30
--
-14.50
0.94
-0.39
0.31
2.09
-1.75
-2.06
6.52
-2.63
-0.58
1.16
1.17
1.24
6.02
- i n
C .30 - 0 . 1 8 - 1 . 1 2
0
moisture reading for November not available.
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
*
e v a p o t r a n s p i r a t i o n m e a s u r e d b y w e i g h i n g l y s imete r m e t h o d (see met hodol ogy),
r un off w a s not m e a s u r e d b u t a s s u m e d to be zero.
indicates amount of water whi ch entered pro file during flooding.
covered with plastic.
Zer o va l u e s for PPT and ET following this rep resents the per iod the plot was
v a l u e s f o r J a n u a r y t o M a y , 197 5, n o t m e a s u r e d b u t a s s u m e d t o e q u a l t h e m e a s u r e d E T v a l u e s f o r J a n u a r y to M ay , 1976.
data not available due to equipment malfunction.
3.31
130
Change soil water
content, ASWC
1976
; Nearly
Total
Appendix Table 24.
Monthly soil profile water balance to the 150 cm depth for rep 2, native range treatment, Peabody Big Sky Mine, January, 1975
to April, 1976. A negative value indicates a loss of water from the profile and a positive value indicates a gain of water in
the profile. All data are presented in centimeters.
1976
1975
Hydrologic Component
Precipitation, PPT
Evapotranspiration, E T 1
Runoff, R O 2
Water flow, WF
Feb
Mar
Apr
M»y
Jun
2.30
2.00
2.50
5.60
8.10
7.40
Jul
Nov0
Dec
Yearly
Total
Aug
Sep
Oct
0.00
0.00
2.00
3.60
2.60
44.99
Jan
Feb
Mar
Apr
Miy
0.33
1.96
2.00
4.98
6.50
54.26
-0.81 -2.99 -3.13 -2.80 -3.76
-35.55
0.00
0.00
0.00
-0.70
-3.20
-1.50
-25.82
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-1.00
1.48
0.60
-0.41
-5.66
-2.51
-2.52
-2.82
-0.59
0.16
1.06
-0.11
-12.32
-0.54
1.44
1.78 -3.62
—
-13.26
0.49
0.49
-0.03
2.39
-1.32
-2.04
6.37
-2.82
-0.59
1.46
1.46
0.99
6.85
-1.02
0.41
0.65 -1.44
—
5.45
-0.61* -2.99* -3.13* -2.80* -3.76* -6.93
0
moisture reading for November not available.
1
e v a p o t r a n s p i r a t i o n m e a s u r e d b y w e i g h i n g l y s i m e t e r m e t h o d (see m e t h o d o l o g y ) .
2
r u n o f f w a s not m e a s u r e d but a s s u m e d t o b e zero.
0.00
0.00
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
indicates amount of water which entered profile during flooding.
Zero values for PPT and ET follwing this represents the period the plot was
covered with plastic.
v al ues for J a n u a r y to May, 1975, not m e a sured but a s s umed t o equal t h e m e a s u r e d ET v a l u e s for J a n u a r y to May, 1976.
d a t a not ava ilabl e due to equ ipmen t malfunction.
0.00
131
Change soil wat er
content, ASWC
Jan
Period
Total
Jan. '75A p r . '76
Appendix Table 25.
Monthly soil profile water balance to the 150 cm depth for rep 3, native range treatment, Peabody Big Sky Mine, January, 1975
to April, 1976. A negative value indicates a loss of water from the profile and a positive value indicates a gain of water in
the profile. All data are presented in centimeters.
•
1975
1976
3.60
2.60
54.17
-0.70
-3.20
-1.50
-35.92
0.00
0.00
0.00
0.00
0.00
Wat er flow, WF
-6.'7
-0.04
0.87
Change soil water
content, ASWC
-6.77
1.26
1.27
Hydrologic Component
Precipitation, PPT
Evapo1
transpiration, ET
Runoff, RO^
Jan
Feb
Mar
Apr
n»y
Jun
Jul
Aug
Sep
Oct
2.30
2.00
2.50
5.60
8.10
7.40
4.40
13.67+
0.00
2.00
0.00
0.00
0.00
-0.81* -2.99* -3.13* -2.80* -3.76* -6.93 -10.10
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0
moi sture rea d i n g f or N o v e m b e r not available.
1
eva potra nspir atio n m e a s u r e d b y wei ghing lysimeter rethxl (see m e t h o d o l o g y ) .
runoff was not measured but
Feb
Mar
Apr
Msy
1.96
2.00
4.98
6.50
63.44
-0.81 -2. 99 -3. 13 -2. 80 -3. 76
-45.65
0.33
0.00
0.00
0.00
0.73
-1.32
1.40
1.09 -2.81
—
--
1.83
-1.80
0.37 -0.04 -0.63
—
—
0.00
0.00
A S W C s h o w n f o r O c t o b e r a n d N o v e m b e r o b t a i n e d b y d i v i d i n g A S W C f o r O c t o b e r I t o D e c e m b e r I b y 2.
a ss umed to b e zero.
indicates amount of water which entered profil: during flo oding.
covered with plastic.
values for January to May
Nov0
Zero val ues for PPT and ET fol lowin g this rep resen ts the period the plot was
1 9 7 5 , n o t m e a s u r e d b u t assiaeed t o e q u a l t h e m e a s u r e d E T v a l u e s f o r J a n u a r y t o M a y , 197 6.
data not available due to equipment malfunction.
Period
Total
Jan . '75A p r . '76
0.00
132
Dec
Yearly
Total
3
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Soil water and solute*
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