&EPA
United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/7-79-122
Laboratory August 1979
Cincinnati OH 45268
Research and Development
Utilization of Fly
Ash and Coal Mine
Refuse as a Road
Base Material
Interagency
Energy/Environment
R&D Program
Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-79-122
August 1979
UTILIZATION OF FLY ASH AND COAL MINE REFUSE
AS A ROAD BASE MATERIAL
by
Roger C. Wilmoth and Robert B. Scott
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publi-
cation. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
11
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution con-
trol methods be used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and economically.
This report evaluates the environmental effects of the use of coal-
related waste products, fly ash and coal mine refuse, as road base mate-
rials. Fly ash is a waste product from coal-powered, steam-generating,
electric energy plants. It was utilized as a stabilizing agent to fill the
voids in the refuse. In cases of alkaline fly ash, it would serve to
neutralize acidity produced by the pyritic coal mine refuse. The mine
refuse and other reject materials are produced from the coal mining process
and preparation plants and were used as the load-bearing aggregate. Be-
cause of the recent emphasis on the expansion of the coal industry, the
technology for utilizing these readily available waste materials as con-
struction material needs reliable definition. The documentation of the
cost, effectiveness, physical stability, and chemical characteristics of
the leachate percolating through the base material is presented in this
report. These data will be of interest to agencies, industry, and individ-
uals who are involved in utilizing waste material for environmentally
acceptable construction purposes. For further information, contact the
Resource Extraction and Handling Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
-------
ABSTRACT
The U.S. Environmental Protection Agency conducted a U-year study on the
utilization of two readily available coal-related waste products as road base
materials in a parking lot. The materials consisted of fly ash from a coal-
powered, steam-generating, electric energy plant and coal mine refuse produced
from a coal preparation plant. The construction area was divided into three
segments with a drainage monitoring system installed at each site. Chemical
characteristics of the effluents discharging from the different base-course
mixtures were documented. All materials were mixed and placed with standard
highway construction equipment and three areas received the same surface
treatment of 7.6-cm (3-in) base course and 2.5-cm (l-in) wearing course of
asphaltic concrete.
Area 1 was composed of a 30.5-cm (12-in) deep mixture of 75-percent coal
mine refuse (CMR) and 25-percent fly ash (FA). The effluent water quality
was found to be environmentally acceptable. A small intermediate area located
along the edge of the pavement produced intermittent slugs of undesirably high
acid and metal concentrations.
The composition of the Area 2 base material was primarily the same as
Area 1 except for the addition of 5 percent by weight of lime in the upper
15.2-cm (6-in) lift. Intermittent slugs of boron concentration were noted
during successive winter months.
Area 3 consisted solely of 38.1-cm (15-in) of coal mine refuse. The
area continues to produce consistently unacceptable acid and metal concen-
trations in the discharge.
Effluent quantities from each of the test areas were surprisingly small;
i.e., approximately one liter per month from each sampling pipe.
Physical structural characteristics of the road base material indicated
that these waste products can be successfully used as a base or subbase mate-
rial when properly compacted and/or stabilized. Monitoring of the physical
and chemical characteristics of the road material began in the summer of 1973
and was discontinued in August 1977.
iv
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CONTENTS
Page
Foreword 1:L1
Abstract iv
Figures vi
Tables viii
Acknowledgments i-x
1 Introduction 1
2 Conclusions 15
3 Recommendations 17
k Procedures 18
5 Results 20
6 Discussion ^7
References ^8
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FIGURES
Number
1 Coal consumption and ash production by U.S. electric
utilities
Page
2 Paving sketch for the coal mine refuse-fly ash road base
study ^
3 Typical cross-sections of the three road bases (as-built) ... 5
k Excavation of existing ground to subgrade level (Area 2) .... 7
5 Placement of polyethylene sheeting and perforated PVC piping
on subgrade for water sampling purposes (Area 2) 8
6 Mixing the refuse and fly ash with an endloader (Area 2) .... 9
7 Placing the refuse-fly ash mixture base material (Area 2) ... 10
8 Grading the base material (Area 2) 11
9 The prepared base material after lime was added to the top
6 in (15-2 cm) - Area 2 12
10 Placement of the base-course asphalt CArea 2) 13
11 The finished project 1^
12 Drainage monitoring system for road base study 19
13 Gradation curves for Humphrey refuse and refuse-fly ash
blends 22
ih Gradation of material removed from base sections during plate
bearing tests 25
15 Deflections for repeated load applications, Area 1, top of
base 28
16 Load deflection curve for Area 1, top of base 29
17 Comparison of effluent pH from each tested area 31
VI
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Number Page
18 Comparison of acidity /alkalinity in the effluents from each
test area ......................... 32
19 Comparison of aluminum concentrations in the effluents from
each test area ...................... 33
20 Comparison of boron concentration in the effluents from each
test area ......................... 3^
21 Comparison of iron concentrations in the effluents from each
test area ......................... 35
22 Comparison of sulfate concentrations in the effluents from
each test area ...................... 36
23 Comparison of suspended solids in the effluents from each
test area ......................... 37
2k Acidity /alkalinity and pH trends from Area 3 (all-refuse) ... 38
25 Aluminum and iron trends from Area 3 (all-refuse) ....... 39
26 Boron trends from Area 3 (all-refuse) ............. ^0
27 Sulfate and suspended solids trends for Area 3 (all -refuse) . . hi
28 Rainfall for each sample date reported as total precipitation
from one sample date to the next ............. 1*2
vii
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TABLES
Number Page
1 Construction Costs (1973) 6
2 Moisture-Density Data from Crown Parking Lot at Time of
Construction 21
3 Moisture-Density Results Associated With Plate Bearing
Testing 23
U Results of Plate Bearing Tests 27
5 Chemistry Analyses of Water Samples for Sample Site C
(Area l) ^3
viii
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ACKNOWLEDGMENTS
The cooperation of the following persons was invaluable to the completion
of this project: Ronald D. Hill, EPA, Cincinnati, Ohio; Dr. David Anderson,
Pennsylvania State University, State College, Pennsylvania; Al Babcock,
Monongahela Power Company, Fairmont, West Virginia; William Harman and Fred
Queen, Harman Construction Company, Grafton, West Virginia; and, William Light
and Greg Barbe, Christopher Coal Company, Osage, West Virginia.
Special thanks are extended to James L. Kennedy, Harry L. Armentrout,
J. Randolph Lipscomb, Robert M. Michael, Ralph S. Herron, Paul H. Moore,
Loretta J. Davis, and Daniel L. Light of the EPA Crovn Mine Drainage Control
Field Site.
ix
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SECTION 1
INTRODUCTION
A study was conducted to utilize two coal-related waste products, fly
ash and coal mine refuse, as road base materials at the U.S. Environmental
Protection Agency's (EPA) Crown Mine Drainage Control Field Site near
Morgantown, West Virginia.
Fly ash is a waste product from coal-powered steam-generating stations
that supply a major portion of the nation's electric energy requirements.
In 1975> total ash collection, which includes fly ash, bottom ash and boiler
slag, soared to a record 5^ million tonnes/yr (59.5 million tons/yr) resulting
from the burning of approximately 363 million tonnes (1+00 million tons) of
coal. Only 1^.6 percent of the ash material is being utilized as construction
material (concrete, fill material, asphalt mix, etc.) or as a soil amendment
for orphaned strip mines and coal mine refuse piles. This material is readily
available particularly in the Appalachian Region for road base material.
Approximately 1.0 million tonnes (l.l million tons) of fly ash and 317,000
tonnes (350,000 tons) of bottom ash were collected during 1975 in the
Monongahela River Basin. Figure 1 shows the production of ash material in
the United States.
Coal refuse, gob, and other reject materials are produced from the coal
mining process. Stringent environmental standards require that a large per-
centage of coal be washed or prepared to make it environmentally acceptable
for consumption, thus yielding more refuse. The mining, crushing, and washing
process tend to concentrate many impurities in the refuse and gob. Most coal-
cleaning methods employ gravity separation to remove impurities; thus, the
more dense materials such as clays, shales, and pyrite lenses are removed to
the refuse dump. This waste material may be extremely toxic (pyritic in
nature) and usually requires special handling and disposal to prevent air and
water pollution problems. Average coal mine refuse produced for the six-year
period between 1968 and 1973 was 91 million tonnes/yr (100 million tons/yr).
This study was to utilize these two waste products (coal mine refuse and
fly ash) in the construction of a parking lot to determine their usefulness
as a road base material in lieu of an environmental detriment. An evaluation
was made to determine if water percolating through the base material would
leach undesirable material and become a pollution problem.
West Virginia University, Monongahela Power Company, and Christopher
Coal Company cooperated with EPA in this study. Dr. David Anderson (previ-
ously with West Virginia University) designed the base-course mixtures. The
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W
O
O
I
O
Q.
O
O
700
600-
500-
400-
300-
200-
g 100
0-
1950
PROJECTED
COAL CONSUMPTION
PROJECTED
ASH PRODUCTION
ACTUAL
COAL CONSUMPTION
BOTTOM
ASH &
BOILER
SLAG
TOTAL ASH
PRODUCTION
80
FIGURE 1. Coal consumption and ash production
by U.S. electric utilities.
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Fort Martin Power Station (Monongahela Power Company) supplied fly ash from
their coal-fired power plant, and the Humphrey Cleaning Plant (Christopher
Coal Company) supplied coal mine refuse.
DESIGN OF TEST
In each of the "base mixtures, the coal mine refuse served as the load-
bearing aggregate. In the coal mine refuse-fly ash system, the purpose of
the fly ash was l) to fill the voids and thereby reduce the permeability of
the system and 2) to neutralize acidity production from the pyritic refuse
material.
In the coal mine refuse-fly ash-lime system, the lime was added l) to
promote pozzolanic or other cementing action that would occur in the fly ash
and, 2) to provide an additional buffer for possible acidity production. The
lime-fly ash matrix filling the voids was designed to harden appreciably,
thereby increasing the strength and decreasing the permeability of the mixture.
The area to be paved was already at finished grade. It was necessary to
excavate from 30.5 to 38.1 cm (12 to 15 in) for the base and 10.2 cm (k in)
for the asphalt.
The construction area (Figure 2) was divided into three segments to in-
vestigate different base-course mixtures. Area 1, covering 770 sq. m (920 sq
yd), was the largest of the three and, as the main entrance and parking area,
was subject to the heaviest traffic. The base course for Area 1 (Figure 3)
was composed of a 30.5-cm (12-in) deep mixture of 75-percent coal mine refuse
(CMR) and 25-percent fly ash (FA). The materials were mixed with an end-
loader prior to placement, and placed in two 15-cm (6-in) lifts. A three-
wheeled steel roller compacted the mixture.
Area 2, with an area of l8U sq m (220 sq yd) was smaller than Area 1 and
subject to less traffic. The base was placed in two lifts. The first 15-cm
(6-in) lift was the same mixture used in Area 1 (75-percent CMR and 25-percent
FA). On the top 15-cm (6-in) lift, five percent of lime (by weight) was mixed
with the CMR-FA mixture by repeated blading with a road grader. Weight calcu-
lations for lime addition were based on CMR-FA density measured during con-
struction. Typical compacted densities were around 1920 kg/cu m (120 Ib/cu
ft). At five percent by weight, the lime requirement for Area 2 was approxi-
mately 2720 kg (6000 Ib) or 15 kg/sq m (27 Ib/sq yd). Considerable difficulty
was encountered in obtaining adequate in-place mixing of the lime with the
CMR-FA mixture, because the lime flowed like water in front of the grader
blade. Mixing the constituents before placement of the base would avoid the
problem. The lime addition was made to offset possible acidity production of
the refuse and to enhance cementing of the fly ash.
Area 3 was the same size as Area 2 but was subject to the least traffic.
The base course for Area 3 consisted solely of 38 cm (15 in) of coal mine
refuse placed in two lifts (Figure 3).
All three areas received the same surface treatment (Figure 3); i.e., a
two-wheeled steel roller individually compacted 7.6 cm (3 in) of base course
3
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0.4m (15") COAL REFUSE BASE
I
6.1m (20') I
-*- d
" 4U.OIII UUU ) 7 '!
'&-:$-ffi':G%&$!?a. ^y$$&$$38:$
^§^^^4^33.2M^y«j'!Jj
QQ
6.1m (20')
t
PLANT BUILDING
12.2m x 30.5m
(40' x 100')
"Uj^S^^SiV^A
;:::(
• •
: :
?'
(9
!;••;
i;!;
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m:
v
::• «r»Q I .v
a 770 sq m
«*92
*.<
^
bi**-
0
:>:
:•:•
i^s-
*.
CROWN. W. Va.
(UNINCORP.)
W.Va. ROUTE 37
15.2m (50'J
8.2m (27')
0.3m (12") 75% REFUSE/25% FLY ASH BASE
0.15m (6") 75% REFUSE/25% FLY ASH FIRST BASE COURSE
0.15m (6") 75% REFUSE/25% FLY ASH PLUS 5% BY WT. HYDRATED LIME
SECOND BASE COURSE
SCALE: 1 cm = 4.8 m
1 HI = 40 ft
O-CATCH BASIN
FIGURE 2. Paving sketch for the coal mine refuse-fly ash road base study at
the U.S. Environmental Protection Agency's Crown Mine
Drainage Control Field Site.
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AREA 1
2.5cm (lin) WVA DOH WEARING II
7.6cm (3in) WVA DOH BASE I
30.5cm (12in) FLY ASH TREATED COAL
MINE REFUSE 757. CMR-25% FA
COMPACTED SUBGRADE
AREA 2
2.5cm (lin) WVA DOH WEARING II
7.6cm (3in) WVA DOH BASE I
15cm (6in) LIME-FLY ASH TREATED COAL MINE REFUSE
15cm (6in) FLY ASH TREATED COAL MINE REFUSE
COMPACTED SUBGRADE
\vo\\\\\\\S\\\\\\\\\\a
AREA 3
2.5cm (lin) WVA DOH WEARING II
7.6cm (Sin) WVA DOH BASE I
38cm (15in) COAL MINE REFUSE
COMPACTED SUBGRADE
FIGURE 3. Typical cross-sections of the three road bases (as built).
-------
asphalt and 2.5 cm (I in) of wearing course asphalt. The asphalt complied
with West Virginia Department of Highways Standard Specifications for Roads
and Bridges outlined in Section kOI for Base 1 and Wearing 2 Courses.
A pictorial history of construction of Area 2 is presented in Figures H
through 11.
COST
In Table 1, the cost of the construction is detailed, (l) The fly ash
and refuse were provided to the contractor at no charge; thus, the only ex-
pense to the contractor was transportation from the source to the site. The
cost of each treated area was not determined. Average cost of the pavement
was $10.92 per sq m ($9-13 per sq yd). These costs are not necessarily repre-
sentative of costs that would be obtained for a large project where more so-
phisticated mixing equipment would be necessary and where the efficiency of
the operation could be greatly improved.
TABLE 1. CONSTRUCTION COSTS (1973)
Payroll and taxes $3957
Materials 2986
Equipment charges (includes moves) ^968
Miscellaneous charges 1+99
$12,1*16
NOTE: The above figures do not include any company overhead or profit.
-------
Figure 4. Excavation of existing ground to subgrade level (Area 2).
-------
.. -V^ '-f -**•«*—. T-*
^*r- >-£•"
*••», .
Figure 5. Placement of polyethylene sheeting and perforated - PVC piping on
subgrade for water sampling purposes (Area 2).
-------
Figure 6. Mixing the refuse and fly ash with an endloader (Area 2).
-------
Figure 7. Placing the refuse-fly ash mixture base material (Area 2).
-------
Figure 8. Grading the base material (Area 2).
-------
ro
Figure 9. The prepared base material after lime was added to the top 6 in (15.2 cm)
(Area 2).
-------
Figure 10. Placement of the base-course asphalt (Area 2).
-------
Figure 11. The finished project. Area 1 extends from the extreme right side of the
picture to the near side of the building (where cars are parked). Area 2
extends from the left-front corner of the building to the left rear corner.
Area 3 covers the area from the right-front corner of the building to the
right-rear corner (past storage silos).
-------
SECTION 2
CONCLUSIONS
AREA ONE (COAL MINE REFUSE/FLY ASH)
Chemical Characteristics
The excellent compaction and particle interlock of the base material
minimized the flow of subsurface water, particularly through the center of
the area.
Chemistry data collected at Point C were biased by its physical location
along the edge of the pavement and by lime spilled or carried over from
Area 2. Intermittent spikes of boron, acidity, iron, aluminum, and other
metals were noted.
Physical Characteristics
The permeability of the subbase and the moisture gradient in the fly
ash/refuse mixture indicates a tendency for the fly ash in the mixture to
retain water.
Physical appearance of the subbase material removed during the plate
bearing tests in Area 1 indicated that the material was well compacted with
excellent particle interlock and could only be removed with considerable
chiseling and prying. There was no evidence of slaking or other degradation.
AREA TWO (COAL MINE REFUSE/FLY ASH/LIME)
Chemical Characteristics
Spikes of boron concentrations of 30 to HO mg/1 occurred during succes-
sive winter months (197^-76).
Physical Characteristics
During plate bearing tests in Area 2, it was necessary to use an air
chisel to remove the portion of material mixed with lime. It is estimated
that the compressive strength of the material was at least 3.5 N/sq. mm
(500 psi). Mixing of the lime in the upper 15 cm (6 in) of Area 2 was less
than adequate.
15
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AREA THREE (ALL COAL MINE REFUSE)
Chemical Characteristics
Chemical data collected at the discharge of this area continued to show
increasing concentrations of environmentally unacceptable chemical constit-
uents in the effluent; therefore, the use of coal mine refuse without fly ash
and/or lime would not be considered an acceptable road base material.
Physical Characteristics
Loss-on-ignition test performed on a small cross-section of the road
base material in all-refuse Area 3 showed an ignition loss of 72 percent
indicating it to be predominately coal with little rock.
GENERAL OBSERVATIONS
Chemical Characteristics
Because the test areas were in a parking lot, the base materials were
poorly drained. Even so, the volume of effluent collected from each sampling
pipe was surprisingly small (on the order of one liter per month). Though
the intermittent discharge of pollutants from Area 2 and the intermediate
area between Areas 1 and 2 were disturbing in terms of concentration, they
represented almost negligible pollutant loads because of the small volume of
discharge.
Physical Characteristics
Results obtained from the plate bearing tests were indicative of low-
quality granular materials suitable as a subbase but of questionable value as
a base coarse directly under asphaltic concrete designed to carry heavy loads.
Coarse material that was removed from test holes and allowed to sit over-
night in the rain with subsequent drying the following day resulted in slaking
of the large particles. Confinement under the pavement surface effectively
stopped physical degradation of both the plain coal refuse and the coal refuse-
fly ash mixtures.
16
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SECTION 3
RECOMMENDATIONS
It is recommended that additional research is needed to determine the
long-term effects of service (frost, moisture, traffic loading, etc.) on the
properties of coal mine refuse and to determine optimal materials and mixtures
for the stabilization of different sources of refuse.
Additional research on the use of coal mine refuse in civil engineering
construction is needed. Emphasis should be placed on use in areas with ex-
cellent drainage so that both water contact time and the tendency for water
retention by the base materials would be reduced.
17
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SECTION k
PROCEDURES
A drainage monitoring system was installed between the base course and
the subgrade (Figure 12). The drainage monitors were 6.U-m (21-ft) joints of
3.8-cm (l^-in) perforated PVC pipe laid on 6-mil polyethylene plastic sheeting.
The base course was carefully placed over the pipes. Discharges from the
pipes drained into catch basins and were collected in plastic containers.
Samples were generally collected on a weekly basis during the early part of
the study and generally on a monthly basis during the later phases.
The following methods were employed for chemical analyses: conductivity
and pH were determined potentiometrically; suspended solids, boron and alka-
linity were determined by EPA methods; (2) total iron, aluminum, magnesium,
manganese, sodium, cadmium, nickel, lead, zinc, and copper were measured by
atomic absorption spectroscopy; (2) sulfate was measured indirectly by atomic
absorption (adding barium chloride to the sulfate aliquot, then analyzing for
residual barium); (3) acidity was measured by the Salotto acidity method (k)
adding hydrogen peroxide to oxidize the metals, then titrating the cold sample
to pH 7.3; and, rainfall was recorded by a Belfort Universal-type rain gage.
Density of the base material was determined by the ASTM D-1556-61j sand-core
method. (5)
18
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WEAR COURSE
,BASE.COURSI
o * »
l'<
\r "
\*>
\ i cr f f
*> LAST LIFT
o x^> . Z> '
' <* tf n tf
„ FIRST LIFT
c?'— <^ -
^ <7 1 Q
0 \,'*i^
^ '
-------
SECTION 5
RESULTS
PHYSICAL CHARACTERISTICS
Field compaction of the base materials was satisfactory; the density of
the in-place materials exceeded the laboratory design values (Table 2). A
more complete discussion of the physical capabilities of the base material
has been presented by Moulton, et al (6) and Anderson. (7)
Compaction and physical characteristics of coal mine refuse were evalu-
ated by Dr. David Anderson (7) under a consulting service contract. Dr.
Anderson reported:
"Field and laboratory moisture-density data taken at the time
of construction are given in Table 2. In Areas 1 and 2, the field
densities were higher than those obtained in the laboratory. This
may be due to the omission of the plus 3A-inch (l.9-cm) material
in the laboratory tests or, more likely, may be due to the differ-
ence in the nature of field compaction versus laboratory compaction.
This point needs to be investigated with respect to coal mine refuse
and its potential for degradation (and subsequent densification)
under compaction, both in the laboratory and in the field. As ex-
pected, the lime treated material was consistently lower in density
than the untreated fly ash/refuse blend.
Gradation curves for the 75-25 refuse/fly ash blend before and
after field compaction are given in Figure 13. The before and
after gradation curves show very little evidence of degradation.
This is in keeping with visual observations made during actual field
compaction. The change in gradation between the blend and the plain
refuse is due to the addition of fly ash. The increase in minus
100-mesh material from 3 percent to 2k percent indicates about 21-
percent fly ash in the refuse/fly ash blend, slightly less than the
25-percent specified.
In July of 197^» approximately one year after the initial con-
struction, a ten-inch (25.it-cm) or twelve-inch (30.5-cm) diameter
section of pavement was removed in Areas 1, 2, and 3. A plate
bearing test was run on the surface of each base section as well
as on the material directly underlying each base section. Moisture-
density and gradation determinations were made on the in situ mate-
rial following each plate bearing test. The results of the
moisture-density tests are given in Table 3. The data are in
20
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TABLE 2. MOISTURE-DENSITY DATA FROM CROWN PARKING LOT AT TIME OF CONSTRUCTION
Test Treatment of
area refuse
1 15% Refuse -
25% Fly ash
2 15% Refuse
25% Fly Ash with
5 % lime, by weight
3 Plain refuse
Test condition
Laboratory
2
Field, during construction
Laboratory
2
Field, during construction
Laboratory
2
Field, during construction
Dry density,
pcf kg/cu m
110. U
123.1*
102.0
107. **
96.9
69.6
1770
1980
1630
1720
1550
1110
Moisture,
percent
7.0
k.k
h.O
U.7
5.6
10.1
ASTM D698-70, Method C, U-in mold and minus 3A-in material
-ASTM D 1556-61*
-------
100
ro
75-25 REFUSE-FLY ASH
BEFORE COMPACTION
75-25 REFUSE-FLY ASH
AFTER COMPACTION
PLAIN REFUSE,
TYPICAL HUMPHREY
#200 #100
SIEVE SIZE
1/4in. Vain. 1in. 2in.
.64cm 1.3cm 2.5cm 5.1cm
FIGURE 13. Gradation curves for Humphrey refuse and refuse-fly ash blends. (7>
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TABLE 3. MOISTURE-DENSITY RESULTS ASSOCIATED WITH PLATE BEARING TESTING
(7)
Depth,*
inches
0-6
10-12
12-16
0-lJg
0-4
l%-3
3-7
10
12-16
0-6
10-12
cm
0-15
25-30
30-40
0-4
0-10
4-8
4-18
25
30-40
0-15
25-20
Dry density,
Moisture, percent Ib/cu ft kg/cu m
AREA 1 - 75/5-25$ REFUSE - FLY ASH
8.1 110.0 1760
11 . 0 -
11.1* 111.8 1790
AREA 2 - 75$-25$ REFUSE - FLY ASH WITH 5$ LIME
10.6
14.5 103.0 1650
16.2
16.6
20 . 5 -
15-1 99.4 1590
AREA 3 - 100$ REFUSE
13.5 70.7 1330
15.4
*Measured in base section alone, excluding asphaltic concrete.
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reasonable agreement with the data obtained at the time of con-
struction (Table 2). The discrepancies between the two data sets
are attributed to testing variability rather than to any signifi-
cant change in material properties during the one year of service.
The coal mine refuse in Area 3 is considered typical of the
Humphrey coal mine refuse. As sampled during the plate bearing
testing, the refuse appeared to be predominately coal with little
rock. During the construction, the contractor encountered some
Humphrey refuse that was exceedingly high in coal content. This
accounts for the anomalous density and appearance of the material
in Area 3 (Tables 2 and 3). To substantiate the suspected high
coal content of the material from Area 3, loss-on-ignition tests
were performed on material from each of the base sections sampled
during the plate bearing testing. The results are as follows:
Area 1, 16-percent loss
Area 2, 16-percent loss
Area 3, 72-percent loss.
Gradation curves for representative material removed during
the plate bearing testing are given in Figure lU. The curves for
the material from Areas 1 and 2 are similar to those in Figure 13,
indicating little or no change in gradation during the one year of
service. The gradation curve for the material from Area 3 is sig-
nificantly different than the typical Humphrey refuse shown in
Figure 13. This reflects the physical appearance and the open and
porous nature of the material as it was removed during the plate
bearing testing. (8) These factors could account for the quality
of the water collected from Area 3- Because of its atypical nature
(density, gradation appearance and loss on ignition) the portion
of Area 3 that was sampled probably does not represent typical be-
havior for the unstabilized coal mine refuse.
The- change in moisture content with depth of the ash-refuse
mixture in Area 2 is of particular interest. Just under the
asphaltic pavement, the base was noticeably drier than at depth.
The material directly under the base is old weathered coal mine
refuse that is reasonably permeable. This permeability was con-
firmed by the rapidity with which rain water drained from the
test hole after a sudden downpour after the completion of testing.
The permeability of the subbase and the moisture gradient in the
fly ash/refuse mixture indicates a tendency for the fly ash in the
mixture to retain water. At 20.5-percent moisture, the fly ash in
the base mixture is sufficiently wet such that water can be squeezed
from it. In both Area 1 and 3, just below the asphaltic concrete,
the base mixture was significantly wetter than when placed, again
indicating a tendency for the fly ash to take up and hold moisture.
Still, in spite of the saturated condition of the fly ash in these
areas, there was no apparent slaking of the coal mine refuse as
might have been expected.
-------
ro
100
90
80
3 70
- O AREA 1
- O AREA 2
- A AREA 3
i-
z
UJ
O
oc
UJ
Q.
60
50
#200 #100 #50 #30 #16 #8
SIEVE SIZE
3/sin. %in. I 11/2in. 3in.
1.0cm 1.9cm ' 3.8cm ' 7.6cm
V2in. 1in. 2in.
.64cm 1.3cm 2.5cm 5.1cm
FIGURE 14. Gradation of material removed from base sections
during plate bearing tests.
-------
The physical appearance of the coal mine refuse as it was
removed from the Area 1 and 2 test holes during the plate bearing
testing was of particular interest. The base material was well
compacted with excellent particle interlock and could be removed
only with considerable chiseling and prying. There was no evi-
dence of slaking or other degradation of the refuse itself.
Some very minor staining was observed in three or four of the
coarse particles from each test hole. Some of the coarse mate-
rial that was removed from the hole was allowed to sit overnight
in the rain. With subsequent drying the next day, many of the
large particles had slaked to the point that they easily crumbled
when worked between one's fingers. The differing behavior of
well compacted refuse is in distinct contrast to refuse open to
the weather in a loose, poorly compacted state.
Area 2 was to be stabilized with lime in the upper 6 in
(15 cm) of the section. As this material was removed from the
test hole, it was quite apparent that the mixing of the lime was
less than adequate. The upper 1% inches (3.8 cm) were not ce-
mented at all. The next H^ inches (ll.k cm) contained isolated
pockets that obviously had not received lime. The effectiveness
of the lime was quite dramatic, however. It was necessary to
use an air chisel to remove the portions of the refuse mixture
that contained lime. It is estimated that the unconfined com-
pressive strength of this material was at least 500 psi
(3-5 N/sq mm). There was no evidence of any chemical reaction
with pyritic portions of the refuse. The effective layer of
lime-stabilized material was estimated to be 2 to 3 in (5 to
8 cm) in the area sampled.
Plate Bearing Tests
The results of the plate bearing tests that were performed
on the base and subbase sections are tabulated in Table h. The
plate bearing tests were performed according to ASTM Standard
Method D-1195-64, Repetitive Static Plate Load Tests of Soils
and Flexible Pavement Components, for Use in Evaluation and
Design of Airport and Highway Pavements. The tests were run
confined on plates of either 10-in (25.U-cm) or 12-in (30.5-cm)
diameter, as noted in Table k. Under test load, the coal mine
refuse behaved essentially as a granular material. The deflec-
tions under applied loads became stabilized after only a few
minutes, even at the higher loads. Complete rebound upon re-
lease of the applied loads was obtained in a few minutes.
Load-deflection curves for Area 1 are shown in Figures 15 and
16. These are considered typical of the various results.
The results given in Table lj are based on load-deflection
curves after 10 cycles of repeated load. Values for the modu-
lus of subgrade reaction, k, are based on plate pressure, p,
of 10 psi (0.069 N/sq mm) where
26
-------
(7)
TABLE k. RESULTS OF PLATE BEARING TESTS
Area 1 k, pci
2
P, psi
E, psi3
plate diam, in
1*
depth of test, in
Area 2 k
P
E
plate diam, in
depth of test, in
Area 3 k
P
E
plate diam, in
depth of test, in
Top of base
769
oil
Pl|i|Q
12
U
588
81
151*6
10
U
U76
75
1086
10
U
Bottom of base
385
U2
136
12
16
5U1
87
1UOO
10
16
500
71
1118
10
19
Note: ASTM procedure D-1195-6U was used for these tests.
Based on plate pressure of 10 psi.
At 0.2-inches deflection.
o
Tangent modulus at 20 psi corrected for surcharge (2).
li
Includes thickness of asphaltic section.
To convert pci to kg/cu m, multiply by 27680; to convert psi to N/sq m,
multiply by 7143; to convert in to cm, multiply by 2.5^.
27
-------
0.15
-------
•o
c
3
O
a
10000
8000 -
6000 -
4000 -
2000 -
DEFLECTION, millimeters
.25 2.5 3.8 5.1
0.05 0.1 0.15
DEFLECTION, inches
-4000
0.20
FIGURE 16. Load deflection curve
for Area 1, top of base.
29
-------
and 6 is the deflection in inches. The bearing value, P, is the
plate pressure required to give a deflection of 0.2 in (0.5 cm).
The modulus of elasticity, E, is based on Boussinesq theory with
a correction for the effect of the surcharge. (9) These data are
indicative of a low-quality granular material suitable as a sub-
base but of questionable value as a base course under asphaltic
concrete."
CHEMICAL CHARACTERISTICS
The chemical data resulting from this study are presented graphically in
two formats: first, the relationships of each specific site with respect to
pH, acidity, aluminum, boron, iron, sulfate, and suspended solids are illus-
trated in Figures 17-23; second, the chemical parameters for Area 3 (all-
refuse) can be compared in Figures 2k-2J, Rainfall data for the study period
are shown in Figure 28.
Area 1
Water samples collected at points A and B were averaged and used to
chemically characterize the effluent from Area 1. The excellent compaction
and particle interlock of the base material minimized subsurface water flows
particularly through the center of the area at collection points A and B.
This was evidenced by minimal water volumes collected from these sample points.
On December 15, 1973, an acid mine drainage (AMD) pipeline which was
buried beneath the pavement in the vicinity of the Area 1 and 2 sampling sta-
tions ruptured. This break appeared to affect primarily the boron levels of
Area 2 and the sulfate levels of both Areas 1 and 2. The influx of AMD
appeared to have no residual effects on Area 2. The effluents collected from
Area 1 appeared generally inoffensive throughout the study period. The efflu-
ents were characteristically neutral or slightly alkaline and contained mini-
mal concentrations of aluminum, boron, iron, and sulfate.
Chemistry data collected at point C (Table 5) were not representative
of water quality of Area 1 for the following reasons: This small area was
biased by lime that was spilled or carried over from Area 2 during construc-
tion. Also, sample point C was located near the edge of the pavement and was
subject to lateral infiltration of surface water that normally flooded a
grassy area adjacent to the pavement during precipitation events. This was
further evidenced by overflowing of the water collection container at point C
during flooding. Chemistry data analyzed at this site for the period of
September 1973 to July 1975 showed the effluents to be characteristically neu-
tral or slightly alkaline. On September 10, 1975, the effluent became suddenly
acid with acidity readings of 910 mg/1 and pH of 2.7; however, water samples
collected and analyzed in February 1976 show zero concentrations of acidity
and an increase of pH to 7.1 (see Table 5). Iron and aluminum concentrations
were less than 3.5 mg/1. A similar incident occurred October 13, 1976. The
30
-------
1V
10-
fr
s
7
e
5-
4
3
2-
REAnAREAf] AREA I
ill all 3l
12
11
-10
-9
8
7
6 .
- 5
4
3
S AMPLE
DATES
FIGURE 17. Comparison of effluent pH from each tested area.
-------
U)
500 —
E
K
Z
-i 50—
<
100—
0 —
50-
100-
01
E
£ 500 —
Q
U
<
1000 —
5000-
SAMPLE
DATES
I
1
J
r
|
AREA n
s
9
c.^
E
_ 1
s
Q 7
li
u *•
•
ll-I
"
•i
•
,i
AREAn AR
2U
:
i
EA|
3 1
* « j:
r*- *j r^ *i
(Sl
-
I
r
1
1
I 11
n n
't
h \
III H.I
FT
: r
'
'• n n ' H
UT
'
t
Z. 2 R
' r s e :
* rt -» *
gjjR-csjs" . B s s ;
. -1 f!7fi 1 QT
— 1000
-500
-50
-100
— 0
-50
-100
-500
-1000
-5000
' g ^
7
CJ
FIGURE 18. Comparison of acidity/alkalinity in the effluents from each test area.
-------
100-
50-
•
E
Z
o
| 10-
LU
U
LO w
U) ^
£
3 i.o-
0.5-
n i
SAMPLE
DATES "
AREA n AREA [~|
-
ffi
1
sll
f
n
!5
o
197
l
-
K
3
-r
r
AREA
3
1
-
S|K
r ~
1
r
97
E5 K g & j»
4
p
r
K * r „ 1
£
Tx,
w
?
197
r
se 2
r
00 I
^r
-
(i
4OTC
I
S 5 R
•1Q
77
200
- 100
- 50 ^.
a
E
g
at
-10 z
HI
- s 8
3
3
- 1.0 <
- 0.5
03
FIGURE 19. Comparison of aluminum concentrations in the effluents from each test area.
-------
u
O
u
2
S
50-
10-
\
:
I
m
j 1.0-
)
' 0.5-
1
0.1-
0.05-
n oi-
flPLE
TCC
t
s
AREAfl AREA n AREA •
it] 2U 3l
nil
I
— 1C
q
IN
e
171
5
r
s
\
\
*
-
s
rl?
s| ~
NO
1
^ 1 £
I
sfi
n c^
1Q-
r
m ^ a>
F4
O en
FE. Acid
of fee
rs,
f
r
c
Mine Water line brealc
fed areas 1 and 2.
n
r.
n
^
1- r
CO «, ^ 0 B S 1
iQ7«;
on 12/15/73
s
;
; ;
c| :
i
K
1Q7C 1Q77
100
50
10
5
- 1.0
- 0.5
Z
O
u
Z
o
0.1
0.05
0.01
FIGURE 20. Comparison of boron concentration in the effluents from each test area.
-------
o
O
m
o
in
CO
O)
E
UJ
8
o
500-
100-
50-
10-
5-
i.o-
0.5-
0.1-
U p| F
h
AREAg
iOTE:
AREA
Acid
on
-] AREA
Mine
1
Wafer 1
ine brealc
72/15/73 affected
areas
[
!
T
i
~\
-
rr
ATES 1Q73 •
I and 2.
n
„
:
i
f%
]
-
-
r
f
1Q74
s
^
'
1 9 7 5
;
, 1Q7I
5 ?
!S S S
2 R
1Q77
- 500
- 100
^>
a
- 50 E
I
<
t—
114
- 10 u
0
-5 §
oc
_l
<
0
- 1.0
1
1- 0.5
i
-
L 0.1
FIGURE 21. Comparison of iron concentrations in the effluents from each test area.
-------
OJ
0\
20,000-
10,000 -
5000-
8 1000
S 500
u
o
u
100-
50
10-
SAMPLE
DATES
AREA H AREA |~j AREA |
NO7E. Acid Mine Wafer line break on 12/15/73
affected areas 1 and 2.
1973
1977-
-20,000
-10,000
-5000
- 1000
- 500
-50
10
a
E
Z
O
u
Z
o
-100 5?
FIGURE 22. Comparison of sulfate concentrations in the effluents from each test area.
-------
U)
10,000
5000 -
1000-
500-
O
V
«/>
a
6
S 100
z
10-
SAMPLE
DATES
F5
•* —
AREAH AREAR AREA |
If
j
1
s s
n
1
,
P
fit;
— 1Q73 —
»
N!M
-
ir
n
I
.
sis
N(
. K
DTE. A<
of
S K S
:id Mine Wafer ine brealc on
fecfed areas ] and 2.
A S ^
n
,
T
S I c
1
-------
100
ui
CD
10,000
- 5000
10,000
— 1973-
avg. avg. avg
-1974
TIME, months
FIGURE 24. Acidity/Alkalinity and pH trends from Area 3 (all-refuse).
-------
U)
1.0-
* 1973-
iff
— 1974
f I f
1975
-1976
1.0
TIME, months
FIGURE 25. Aluminum and iron trends from Area 3 (all-refuse).
-1977
-------
O.O1
0.01
1973
TIME, months
FIGURE 26. Boron trends from Area 3 (all-refuse).
-------
10,OOO
5000
_ 1000-
^
01
E
500
v
Z
S 100
50-
10-
sl§
—1973
- 1000 -
- 5OO
Ijfgl §§'s§ I 1
T T
1974-
g» I (NJI- I 00 I
-------
6.O -
5.O-
4.O
FIGURE 28. Rainfall for each sample date reported as total precipitation from one sample date to the next.
-------
TABLE 5. CHEMISTRY ANALYSES OF WATER SAMPLES FOR SITE C (AREA 1
Date
9/27/73
10/lt/73
10/11/73
11/1/73
11/29/73
12/6/73
1/3/71*
1/11/71*
1/17/71*
1/2V71*
1/31/71*
2/7/71*
2/28/71*
3/7/71*
3/21/71*
pH
10.75
10.66
7.93
10.65
10.85
10.85
8.3
7-71.
8.25
9.37
11.0
10.6
8.31*
B.k
9.2
Cond.
670
258
167
320
1(1*0
165
650
2250
1750
1*00
300
1(20
31*0
300
1*80
Acid Alk
0 70
0 1(5
0 130
0 90
o 165
0 88
o 850
o 500
o 190
0 175
0 180
0 70
0 2kO
0 190
0 95
Ca
66
16
2k
26
ko
32
60
300
200
62
1*5
55
65
1*5
75
Mg Fe+3
.k .08
.2 < . 01
.7 < . 01
1.9 <-01
1.0 <.01
.1* < . 01
12 <.01
1*0 .60
35 .1*0
5.6 <.0l
.68 <.01
1(.0 <.01
5 -0 .01*
3.2 .30
3.6 .72
Al
.60
.60
• 90
1.50
.92
.52
1.0
1.8
.80
<.01
1.0
1.2
.62
.80
1.6
Mn Na
<.01 12U
<.01 15
< . 01 13
< . 01 32
<.01 50
<.0l 9
.03 135
.25 1(50
.11* 1*00
<.01 100
.02 22
<.01 50
.02 56
.02 55
.06 28
Boron Cd
-
.06
.29
.86
.31 < . 01
.12
1.0
3.1
3.0
1-5
.1(0 <-03
.50 <-01
.60 <-01
.32 <-01
.6k
Hi Pb Zn
.10 <.01 .07
- <.01
.02
- <.01
<.01 <.01 <.01
_
.05
.10 .12 .12
.02 .08 .08
- <.01 <.01
< . 01 < . 01 . OU
< . 01 < . 01 .06
.10 <.01 <.01
.15 <.01 .08
.18 - .12
Cu SOi
315
32
1*2
<.0l 90
.05 18
.03 19
1*35
.01* 1500
.05 1350
<.01 281
.03 75
<.01 188
.11 5!*
<.01 75
321
JTO
-
125
30
63
260
170
1*25
120
75
500
80
50
150
120
80
SS
-
-
11*0
22
-
220
1220
ll*0
20
1220
11*3
100
1*20
220
170
— — ^ (continued)
-------
TABLE 5. (continued)
Date
UA/7U
l*/l8/7l*
U/25/71*
5/16/71*
5/30/71*
6/6/7U
6/28/71*
7/12/7U
8/16/71*
10/15/71*
2/5/75
2/28/75
3/12/75
U/28/75
6/16/75
PH
8.3
8.1
10.3
7.3
7.2
7.3
7.1*
7.0
7.3
7.1
7.9
7.6
7.6
7.0
7.3
Cond.
550
1*20
185
980
1210
1300
ll*80
530
350
300
2700
1260
lll*0
1700
350
Acid
0
0
0
0
6
0
0
U
0
0
0
0
0
10
0
Alk
100
50
65
60
100
88
72
100
350
81*
167
88
1*8
M.
88
Ca
70
100
32
200
230
2UO
250
90
1*5
6U
1*50
1*65
1*12
507
60
Mg
1*.3
l*.l*
1.0
8.81*
ll*
12
13
5
3.3
6.1
1*5
2.6
1.8
10
28
Ke+3
<.01
<.01
.06
.33
.10
1.10
.75
.1*0
.11*
5
.17
lt.0
1.1
12
.21
Al
.80
.32
2
.32
.9
.60
1.2
1
.52
1.0
.82
.30
.28
.28
.1*0
Mn
.03
.10
.08
.01
.16
.01*
<.01
<.01
<.01
.07
.21
.08
.11
.38
.10
Na
35
1*5
30
21*
80
26
25
12
7.6
3.3
380
5
10
11
l.l*
Boron Cd Hi
1.0 < . 01 < . 01
.85 .02 <.01
.31
1.1* - .1*5
1.7
1.7
1.5
.05
.12 <.01 <.01
.08
5.6 - .28
.16 - .20
.20 - .39
.60 - .61*
.12 <.01 .1*1*
Fb Zn
<.01 .06
<.01 .05
.06
.09 .01*
.05
-
.13
.50
.35 .06
.1*0 .11*
.02
.23
.06
.1*6
.18
Cu SO,
<.01 100
<.01 350
81*
500
.03 800
750
650
190
< . 01 1*5
1UO
< . 01 2100
<.01 1100
<.01 1000
.01 1350
.10 170
JTU
275
30
55
60
70
35
20
170
750
80
1*
SS
770
90
160
300
870
150
90
601»
301*
1*2
1*0
360 11*1*0
10
80
250
(continued)
16
220
980
-------
TABLE 5. (continued)
Date
7/1U/75
9/10/75
9/18/75
10/28/75
1/1U/76
2/11/76
3/23/76
01 7/12/76
10/13/76
2/16/77
3AU/77
It/12/77
7/20/77
8/12/77
pH
8.0
2.67
2.9
1*.1*6
6.0
7-1
6.2
7.0
3.5
5.3
6.1*
7.3
6.9
6.9
Cond.
300
3l»00
2150
900
1280
2500
2000
310
1775
1220
1*200
860
250
168
Acid
0
910
1»50
1*0
20
5
10
0
273
20
10
0
10
6
Alk
111*
0
0
0
1*
15U
30
161
0
10
92
365
90
77
Ca
1*2
1*70
230
180
265
3UO
700
1*2
1*1*0
200
600
175
50
110
Mg
1.5
75
50
22
17
60
1*2
3.2
60
17
75
25
1.8
7.1
Fe+3
<.10
80
28
<.10
.20
3-5
2.5
.1*2
• 70
<.05
.50
.10
.12
6.2
Al
.1*0
36
26
lt.8
.56
1.0
i».e
.16
11
1-5
.28
1.0
.1*0
i*.e
Mn
.10
1*.9
2.6
.72
.36
.1*1
.70
<.05
3.3
.73
1.8
<.05
<.05
1.45
Ha
8.6
12
6.5
2.8
20
1*00
350
6.5
20
60
1*00
23
2
2
Boron
.12
1.2
1.2
.1*1*
.1*5
6.8
• 52
-
-
-
-
-
-
Cd
-
.01*
.05
.05
.01*
.07
.10
<.01
<.01
•c.Ol
<.05
<.05
<.05
,09
Mi
-
.1*1*
-
12
<.01
.22
.1*0
.1*5
.97
.39
.1*6
-
<.05
.21
Pb
.16
.33
.31*
.30
-
.1*5
.60
<.01
•c.Ol
.67
.1*1*
<.05
<.05
1.1.
Zn
.30
2.6
1.U5
.1*5
.50
.1*8
-70
<.0l
1.2
.57
.1*2
.07
.06
2.6
Cu
0
.50
.30
.06
.01*
.02
.01
<.01
<.01
.06
.07
<.05
<-05
.25
soi,
130
1950
1000
600
780
1900
2700
30
ll*25
690
2675
220
60
103
JTU
65
650
160
90
1*0
170
1*0
860
125
20
61
>1000
>1000
>1000
S3
620
1120
250
220
151
116
1*6
50
3300
500
268
6332
2628
3581*
All units are expressed as mg/1 except for pH and conductivity (micrcmhos/cm).
Potassium was less than 12 mg/1.
Strontium content generally less than one mg/1.
-------
effluent became suddenly acid with an acidity reading of 273 mg/1 and a pH of
3.5. Samples collected in March 1977, showed acidity to be 10 mg/1; pH was
6.1*; and iron and aluminum were less than 0.5 mg/1. Similarly, these periods
of high concentration of mine drainage occurred after periods of major precip-
itation. The cause of this spike of acidity in water quality is not really
known. It is possible that lateral permeation of surface water through the
subbase material could have influenced the momentary degradation of water
quality in this particular sample site. If the water were permeating later-
ally, it might not come in contact with the lime that was placed on the upper
portion of the base material. The permeation paths of the water through the
voids in the base material were probably in a constant state of flux as ferric
hydroxide floes were formed during contact of the acid water with fresh lime
surfaces. This in turn impeded the path of water permeation; therefore, sur-
face water could flow to other areas in the base material and flush out acid
water that had been formed previously by pyrite oxidation.
Area 2
The cause of the spike of boron concentrations ranging from 10 to
1+0 mg/1 during successive winter months (197^-77) is not known. It has been
reported (10) that a boron concentration above 1* mg/1 in irrigation water was
generally unsatisfactory for most crops. Experimental evidence concerning the
toxicity of boron to livestock water demonstrated that an upper limit of
5.0 mg/1 would be acceptable. The recommended maximum concentrations for
semi-tolerant and tolerant plants are be 1 and 2 mg/1. (10)
Suspended solids and sulfates ranged as high as 1*000 mg/1 and 10,000 mg/1,
respectively. These high concentrations were not typical of the values for
the period of record. (See Figures 22 and 23).
Because of the intermittent slugs of boron, it is felt that the effluent
quality from this area would be of questionable acceptability. Generally, the
effluents were characteristically neutral or slightly alkaline and had minimal
concentrations (less than 7-0 mg/l) of aluminum and iron and less than 1.0 mg/1
of boron.
Area 3
The quality of the effluent from Area. 3, where the base material was en-
tirely coal mine refuse, continually decreased (Figures 2l|-27). The pH value
of the effluent dropped from pH 7 to near 2.5 and the acidity increased to
nearly 5000 mg/1. The aluminum and iron fluctuated from 3 to 50 mg/1 and
3 to 5000 mg/1 respectively; boron values were less than 1.0 mg/1; and sulfate
concentration ranged to 5000 mg/1; therefore, effluent quality from this area
would make this area environmentally unacceptable.
Comment
It must be emphasized, however, that the volume of water eminating from
these test areas was surprisingly small in all cases. For example, approxi-
mately one liter was collected from each sample pipe over a one-month period.
In view of the small quantities involved, consideration should be given to
applications with better drainage than parking areas.
46
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SECTION 6
DISCUSSION
CONCENTRATION AND LOADS
The sample collection system accumulated a maximum of approximately one
liter of water per month per sampling pipe. Each sample pipe collected water
from approximately a 39-sq m (U20-sq ft) area. This amounts to 0.026
liter/month/sq m.
The "base material in this study was poorly drained. The finished grade
of the parking lot was even with the existing ground requiring excavation for
all material placement. In contrast to this construction, a road would be
well ditched and crowned in the center to encourage rapid removal of surface
water. In terms of water retention, this parking lot application was probably
an extreme-case illustration.
If we use the 0.026 liter/month/sq. m drainage rate and apply an extreme-
case water quality from Table 5 (i.e., TOO mg/1 calcium, 75 mg/1 magnesium,
80 mg/1 iron, 36 mg/1 aluminum, 5 mg/1 manganese, kOQ mg/1 sodium,, a total of
10 mg/1 of boron, cadmium, nickel, lead, zinc, and copper, and 2000 mg/1 sul-
fate, for a total of 3^00 mg/1 total dissolved solids, it is possible to cal-
culate the increase in pollutant concentration in a resultant stream from a
hypothetical use of fly ash/lime stabilized coal mine refuse as a road base
material.
Assuming a 10-km (6.2-mi) road were constructed using lime/fly ash sta-
bilized coal mine refuse as a base material, and further assuming a width of
T m (23 ft), the total surface area would be 70,000 sq m (753,500 sq ft).
If the monthly rainfall were 100 mm (U in), a total of 7000 cu m (1,850,000 gal)
of water would be applied to the road area. At the 0.026 liter/month/sq m
percolation rate, 1820 liters (1*80 gal) of water would result as effluent from
the road base material. Assuming the concentration of total dissolved solids
in the road base effluent to be 3^00 mg/1, the 1820 liters of effluent would
discharge 6190 grams of dissolved solids into the 7000 cu m resulting in an
approximate hypothetical total dissolved solids concentration of 0.9 mg/1.
As previously stated, this is by far an extreme-case illustration.
1*7
-------
REFERENCES
1. Harman, William, Harman Construction Company, Grafton, West Virginia,
Personal Communication. March 197** •
2. Methods of Chemical Analysis of Water and Wastes, U.S. Environmental
Protection Agency, Analytical Quality Control Laboratory, Cincinnati,
Ohio. 1971.
3. Dunk, R., M. A. Mostyn, and H. C. Hoare, General Procedure for Indirect
Determination of Sulfate, Analytical Methods for Atomic Absorption
Spectrophotometry, Perkin-Elmer Corporation, Norwalk, Connecticut.
March 1971.
k. Salotto, B. V., et al. Procedure for the Determination of Mine Waste
Acidity. Paper given at the 15^th National Meeting of the American
Chemical Society, Chicago, Illinois. 1966.
5. ASTM Standards - Part II, 1968, American Society for Testing and Materials,
Philadelphia, Pennsylvania, March 1968.
6. Moulton, Lyle K., Roger K. Seals, David A. Anderson, and S. M. Hussain,
Coal Mine Refuse: An Engineering Material, Fifth Symposium on Coal Mine
Drainage Research, Louisville, Kentucky, October 197^.
7. Anderson, David A., Parking Lot Construction at Crown, W. Va. , Mine
Drainage Control Field Site, Consultants Report to Environmental
Protection Agency, Morgantown, W. Va., August 197^.
8. Wilmoth, R. C., and R. B. Scott, Use of Coal Mine Refuse and Fly Ash
as a Road Base Material, First Symposium on Mine Preparation Plant Refuse
Disposal, Louisville, Ky., October 1971*.
9. Yang, N. C., Design of Functional Pavements, McGraw-Hill Book Company,
New York, 1972.
10. National Academy of Science: Water Quality Criteria, 1972.
1+8
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/7-79-122
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
"Utilization of Fly Ash and Coal Mine Refuse as a
Road Base Material"
5. REPORT DATE
August 1979 (issuing date)
6. PERFORMING ORGANIZATION CODE
EPA 600/12
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Roger C. Wilmoth and Robert B. Scott
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio U5268
10. PROGRAM ELEMENT NO.
1HE623B
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio
13. TYPE OF REPORT AND PERIOD COVERED
Final (1973 thru 19TT)
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The U. S. Environmental Protection Agency conducted a four-year study to
determine the feasibility of using fly ash and coal mine refuse as a road base
in a parking lot. The lot was divided into three areas each receiving the
same surface treatment but with different ratios of fly ash to refuse. Area 1
was composed of 75-percent coal mine refuse and 25-percent fly ash; Area 2 was
composed of the same material as Area 1 with the addition of 5 percent by weight
of lime; and, Area 3 consisted solely of coal mine refuse. All areas were
periodically monitored and with the exception of Area 3 were found to be
environmentally acceptable. Physical structural characteristics of the road
base material indicated that these waste products can be successfully used as
a base or subbase road material when properly compacted and/or stabilized.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
Fly ash
Drainage, mines
Roadbeds
Lime
Neutralizing
Coal refuse
Road base
13B
50A
SOB
68A
91A
91B
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
59
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (R.v. 4-77)
u.» summonnmimesfm an 657-060/5359
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