United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S7-84-051 May 1984
&ER& Project Summary
Investigation of Coal Mine
Effluents—Regrade to Bond
Release
M. F. Bucek and C. R. Gander
The objective of this fact-finding
project was to characterize the effluents
draining from surface-mined lands that
are at various stages of reclamation
preceding final release of bond. To
produce the characterizations, water
quality samples were collected from
sedimentation pond inflow and outflow
on a da4ly basis when flow was present.
and hourly during runoff events at eight
monitoring sites located in Ohio, West
Virginia, Kentucky, Illinois. Kansas,
Texas, North Dakota, and Montana. In
addition, 50 sites located throughout
the major U.S. coal mining regions were
sampled once during or shortly after a
storm event and/or evaluated with
respect to water handling practices.
The water quality data show great
variability in the concentrations of con-
stituents affected by the physical and
mining framework of each reclamation
site. Water quality parameters analyzed
include pH, acidity, alkalinity, specific
conductance, total dissolved solids,
total suspended solids, turbidity, settle-
able solids, total and dissolved iron,
aluminum and manganese, and dis-
solved trace elements—antimony, ar-
senic, beryllium, cadmium, chromium,
copper, lead, mercury, nickel, selenium,
silver, thallium, and zinc.
The field data collection phase for this
project was from August 1979 through
October 1980. AH water quality data
were compiled into a data base and
submitted to the U.S. Environmental
Protection Agency, Industrial Environ-
mental Research Laboratory in Cin-
cinnati as a part of the unpublished
project file.
The total suspended solids concen-
tration limit of 70 mg/L was exceeded
at each monitored site in 8 to 81
percent of the samples. The total iron
concentrations are highly correlated
with the total suspended solids concen-
trations and exceeded 7.0 mg/L at all
but one monitored site in 4 to 75
percent of the samples. The total manga-
nese concentration limit of 4.0 mg/L
was exceeded at three sites in 3 to 38
percent of the samples. Upper or lower
levels of pH (range 6 to 9) were exceeded
in 68 percent of the samples at the West
Virginia site and 4 percent of the sam-
ples from the Texas site. Settleable
solids in excess of 0.5 ml/L/hr were
found in 41 percent of the samples from
the monitoring site in North Dakota.
The Mann-Whitney test of differences
between the sedimentation pond inflow
and outflow concentrations of total
suspended solids was performed to test
the impact of sediment ponds on the
levels of particulate pollutants. The test
results show that there was not a
statistically significant difference be-
tween the inflow and outflow sets of
total suspended solids data from four of
seven monitoring sites or from the mine
survey sites.
The concentrations of total suspended
solids were reduced in 58 to 87 percent
of the samples of daily pond inflow and
outflow. The rest of the samples show
increases in the total suspended solids
in the pond outflow observed during
base flow as well as during runoff
events. The actual pond efficiency was
found to be largely independent of
precipitation levels.
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The efficiency of other water control
structures was observed to be highly
variable, depending mainly on their
design and maintenance.
The full report was submitted in
fulfillment of Contract 68-03-2762
under sponsorship of the U.S. Environ-
mental Protection Agency, Industrial
Environmental Research Laboratory.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Project Scope and Logistics
The project was executed in two
phases. Phase 1 consisted of preparing a
research plan that outlined the technical
approach to be employed by HRB-Singer,
Inc. and by its subcontractor, Commercial
Testing and Engineering, Inc. (CT&E), to
perform research activities and sampling
and analysis services related to the study.
Phase 2 consisted of the actual imple-
mentation of the research plan in two
tasks. The first task included a survey of
50 mine sites. Detailed water quality
sampling of eight in-depth monitoring
sites was performed in the second task.
Each of the in-depth monitoring sites
was equipped with fiberglass Parshall
flumes, automatic samplers, flow meters,
and ram gauge/event recorders. Field
laboratory technicians were stationed at
each of the in-depth sites to maintain the
equipment, to collect water samples, and
to perform the required field analyses.
Field laboratories were set up in close
proximity to the monitoring sites and
equipped for analysis of pH, acidity,
alkalinity, specific conductance, total
dissolved solids, total suspended solids,
and settleable solids. All samples to be
analyzed for total and dissolved metals
and for particle size analysis were sent to
CT&E laboratories in Golden, Colorado,
and in New Holland, Illinois. Daily compos-
ite samples from each monitoring site
were sent once a week to the Bituminous
Coal Research, Inc. Laboratories in
Monroeville, Pennsylvania, as part of the
project's quality assurance program.
Data Summary and Conclusions
Statistical summaries of the water
quality data indicating ranges of the con-
centrations and the variability of the
individual constituents for each monitor-
ing site and for the mine survey sites are
given in the final report.
2
Trends in the concentrations of meas-
ured water quality parameters are in-
fluenced by the proportions of base flow
and surface runoff in the discharge from
each site. Variability of the data is also
affected by physical and mining factors at
each sampling site. Sources of the various
pollutants are diffused throughout the
reclamation sites, and fluctuations m the
pollutant input also contribute to the data
variability. Seasonal changes in precipi-
tation and the mixing of the surface
runoff, spoil leachate, and ground water
that recharge the sedimentation pond
contribute to the complexity of the hydro-
logic system. Leachate from the spoils
can be flushed out during precipitation
and temporarily affect the concentrations
of water quality parameters such as
acidity, pH, alkalinity, total dissolved
solids, and dissolved metals.
Quite often it is difficult to define and
describe the relationships among the
site's physical characteristics, reclamation
and water handling practices, and effluent
water quality. Results of factor analysis
indicate that the slope steepness, the
length of the time period after regradmg
and topsoiling, and the pond sediment
storage volume are the site-specific fac-
tors highly correlated with water quality
parameters.
Water handling practices were ob-
served to vary with the regional differ-
ences of the sites and were adjusted to
the overall site morphology. Water sam-
ples collected during a storm event from
diversion ditches at the monitoring sites
show concentrations of total suspended
solids mostly equivalent to those of the
sediment pond inflow. The main function
of the ditches is to collect the surface
runoff and to divert the flow from problem
areas to a sedimentation pond. The
design, and especially the maintenance,
of these structures are major factors
determining their effectiveness.
Sediment traps used at the sites to
reduce sediment loads in surface runoff
before its entry into a sedimentation pond
were observed to be effective in trapping
only the coarser particles. Their effective-
ness is highly variable and depends
largely on site conditions and mainte-
nance.
The evaluation of sedimentation pond
efficiency in reducing total suspended
solids concentrations was performed by
calculating percent reduction in the con-
centrations of total suspended solids
between the points of sedimentation
pond inflow and outflow. The calculations
were based on daily composite inflow and
outflow samples and indicated an average
daily pond effectiveness. The concentra-
tions of total suspended solids were
reduced in 58 to 87 percent of the
samples taken at the monitoring sites.
The rest of the samples showed increases
in the total suspended solids load in the
pond outflow. These increases were
observed to occur during base flow peri-
ods as well as during runoff events. The
observed efficiency of ponds in reducing
the suspended solids was largely inde-
pendent of precipitation levels and, in
most cases, of the flow conditions as well.
The Mann-Whitney test was performed
to determine if there is a statistically
significant difference in the overall quality
of sedimentation pond inflow and outflow
data pairs. The NULL hypothesis, assum-
ing no difference in the pollutant level of
pond inflow and outflow, was rejected in
approximately 38 percent of the tested
samples. A significant difference in the
concentrations of total suspended solids
in the pond inflow and outflow was
indicated for three monitoring sites. For
the rest of the monitoring sites and the
mine survey sites that were sampled
mainly during storm events, the NULL
hypothesis was not rejected, thus indicat-
ing that the ponds had no substantial
quantitative effect on the total suspended
solids levels.
Concentration levels of water quality
parameters specified as potential pollut-
ants associated with coal mining point
source discharges were compared with
EPA's effluent limitations guidelines spec-
ified in the Federal Register, Volume 48,
January 13, 1981. The total suspended
solids level of 70.0 mg/L was exceeded at
each sampled site in 8 to 81 percent of the
cases. The guideline levels for total iron
concentrations were exceeded at all sites
but one in 4 to 75 percent of the cases
analyzed. Levels of pH in the range of 6.0
to 9.0 were exceeded in 68 percent of the
samples from a West Virginia site and in 4
percent of the samples in Texas. The
specified guidelines for total manganese
were exceeded at three sites in 3 and 38
percent of the samples. The settleable
solids level of 0.5 ml/L/hr was exceeded
in 41 percent of the samples from North
Dakota and in 1 and 2 percent of the
samples from the mine survey sites and
the monitoring site in Ohio, respectively.
Thirty-day moving averages calculated
for daily values of total suspended solids,
total iron, and total manganese were
compared to the limitations guidelines
given for average daily values for 30
consecutive days. The 30-day average for
total suspended solids of 35 mg/L was
exceeded at each monitoring site in 38 to
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100 percent of the samples. The high
percentages of total suspended solids
identified for the in-depth sites in Illinois,
Kansas, Texas, and North Dakota that
exceeded 35 mg/L correspond to the high
number of cases where the guidelines of
3.5 mg/L for total iron were also exceed-
ed. The total manganese level of 2.0
mg/L was exceeded at the in-depth sites
in West Virginia, Kentucky, and North
Dakota.
Trace element concentrations were
determined for samples taken from sedi-
mentation pond outflow at the in-depth
monitoring sites and the mine survey
sites. Most of the elements were below or
close to the detection limits.
Total suspended solids and turbidity
were found to be highly correlated in the
majority of the measurements. However,
the quality assurance program indicated
a progressive error in the turbidity deter-
minations for samples with high concen-
trations of suspended solids.
The total suspended solids concentra-
tions are also very highly correlated with
those of total iron and total aluminum.
The three constituents were found to be
redundant, indicating high interdepend-
ence and a high correlation in the vari-
ability of their values. The same is true
about occurrences of total and dissolved
manganese. Total and dissolved occur-
rences of iron and aluminum are not
strongly correlated, since each of the
parameters measures slightly different
water quality properties. Concentrations
of total iron and total aluminum reflect
changes in the concentration of the total
suspended solids as well as the composi-
tion of the particles in suspension. The
analytical method for determining total
metals calls for vigorous digestion of an
unfiltered sample and indicates the sum
of the concentrations of metals in both
the dissolved and suspended fraction.
Metals are extracted from silts and clays
that, under ambient conditions, are not
easily released into solution.
Approximately 98 percent of the sam-
ples collected during the project and
analyzed for settleable solids yielded
values below 1 ml/L/hr. The detected
values ranged from 1.0 ml/L/hr to 290
ml/L/hr. The values are well correlated
with concentrations of total suspended
solids and in the majority of cases were
detectable only when the total suspended
solids reached concentrations of hun-
dreds or thousands of mg/L. All of the
sedimentation pond discharges charac-
terized by such high concentrations of
suspended solids occurred during runoff
events.
* Twelve surface mines selected to rep-
resent the prevailing mining and physical
conditions in western mining areas were
visited to evaluate the water handling
practices used in reclaiming semiarid and
arid lands. The overall erosional regime of
the western reclamation sites is influ-
enced by short duration, high intensity
precipitation events that produce surface
water runoff with high erosive capacity.
Management and water control prac-
tices used at the western mines are basic
agricultural soil and water conservation
practices. Most of these practices are
fairly standard and result in good erosion
and sediment control. About 20 percent
of the mines visited used irrigation to
reestablish vegetative cover during un-
usually dry periods. Overgrazing of some
recently revegetated sites appears to be
one of the major causes of erosion during
the final stages of reclamation.
Revegetation using native species some-
times presents problems because of the
species' slow establishment rates. Poor
erosion control often results during the
first season after reseeding. In order to
control erosion, a quick cover annual or a
biannual species is used as a "nurse
crop." This practice was observed to
produce very good results.
Utilization and design of various diver-
sion and conveyance structures vary with
the local conditions determined by the
site's physical and mining framework.
Restoring the premining drainage patterns—
particularly stabilizing newdrainage chan-
nels—is one of the difficult tasks that
affects the overall erosional regime of the
reclaimed area.
The majority of the surveyed mines
have constructed sedimentation ponds to
collect water draining from the reclaimed
areas, pit pumpage, and other drainage
from active mining areas, including haul-
age roads. Because of the scarcity of
water in the dry regions, total contain-
ment practices are often implemented for
the sake of water conservation.
There is no conclusive information on
the effectiveness of ponds in removing
suspended solids during runoff events,
even when the ponds are designed ac-
cording to the criteria set forth by the
Office of Surface Mining. Concentrations
of suspended solids during runoff events
in dry regions are extremely high and
often contain large proportions of very
fine particles.
Concern has been expressed over the
sediment removal below baseline levels
and the effects of sedimentation ponds on
the downstream erosional and deposi-
tional conditions. These effects may be
especially pronounced when associated
with sediment retention structures of
relatively long lifespans.
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M. F. Bucek and C. R. Gander are HRB - Singer, Inc.. State College. PA 16801.
J. F. Martin is the EPA Project Officer (see below).
The complete report, entitled "Investigation of Coal M'me Effluents—Regrade to
Bond Release." (Order No. PB84-177 906; Cost: $14.50, subject to change) wilt
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
U.S. GOVERNMENT PRINTING OFFICE: 1984 — 759-015/7716
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
AGENCY
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