United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-85/028 Aug. 1985
Project Summary
Full-Scale Field Evaluation of
Waste Disposal from Coal-
Fired Electric Generating
Plants
Chakra J. Santhanam, Armand A. Balasco, Itamar Bodek,
Charles B. Cooper, John T. Humphrey, and Barry Thacker
This project summary describes re-
sults of a 3-year study of current coal
ash and flue gas desulfurization (FGD)
waste disposal practices at coal-fired
electric generating plants. The study in-
volved characterization of wastes, envi-
ronmental data gathering, evaluation
of environmental effects, and engineer-
ing/cost evaluations of disposal prac-
tices at six sites around the country. Re-
sults of the study provide technical
background data and information to
EPA, state and local permitting officials,
and the utility industry for implement-
ing environmentally sound disposal
practices.
Data from the study suggest that no
major environmental effects have oc-
curred at any of the six sites; i.e., data
from wells downgradient of the dis-
posal sites indicate that waste leachate
has resulted in concentrations of chem-
icals less than the EPA primary drinking
water standards. A generic environ-
mental evaluation—based on a matrix
of four waste types, three disposal
methods, and five environmental set-
tings (based on climate and hydrogeol-
ogyl—shows that, on balance, technol-
ogy exis.ts for environmentally sound
disposal of coal ash and FGD wastes for
ponding, interim ponding/landfilling,
and landfilling. For some combinations
of waste types, disposal methods, and
environmental settings, mitigation
measures must be taken to avoid ad-
verse environmental effects. However,
site specific application of good engi-
neering design and practices can miti-
gate most potentially adverse effects of
coal ash and FGD waste disposal. Costs
of waste disposal operations are highly
system and site specific.
This Project Summary was devel-
oped by EPA's Air and Energy Engineer-
ing Research Laboratory, Research Tri-
angle Park, NC, to announce key
findings of the research project that is
fully documented in six separate vol-
umes (see Project Report ordering in-
formation at back).
Introduction
This study—of current coal ash and
flue gas desulfurization (FGD) waste
disposal practices at coal-fired power
plants—involved characterization of
wastes, environmental data gathering,
evaluation of environmental effects,
and engineering/cost evaluations of dis-
posal practices at six sites around the
country. Results of the study provide
the technical background data and in-
formation needed to help EPA deter-
mine the degree to which disposal of
these wastes needs to be managed in
order to protect human health and the
environment. The study results will also
assist EPA in preparing a report to Con-
gress required under the 1980
Amendments to the Resource Conser-
vation and Recovery Act (RCRA), and
should provide useful technical infor-
mation to federal, state, and local per-
mitting officials and utility planners on
methods for environmentally sound
disposal of coal ash and FGD wastes.
-------
Background on Waste Genera-
tion/Disposal Methods
Coal-fired power plants using con-
ventional combustion technology gen-
erate two major categories of waste ma-
terials: coal ash (fly ash, bottom ash, or
boiler slag) and FGD wastes are gener-
ated in large amounts relative to other
wastes generated at these plants and,
therefore, are usually referred to as
"high volume wastes." Numerous other
wastes, generated in smaller quantities,
are associated with other processes or
maintenance operations in a power
plant; e.g., coal pile runoff, boiler and
cooling tower blowdown, water treat-
ment and maintenance cleaning
wastes, general power plant trash, and
plant sanitary wastes. This project fo-
cused primarily on the high volume
wastes.
Fly ash from coal-fired utility boilers is
collected by mechanical collectors and/
or electrostatic precipitators, fabric fil-
ters, or wet scrubbers. By late 1982, ap-
proximately 103,000 MW of coal-fired
generating capacity—operational units,
units under construction, and units at
various stages of planning—had been
committed to FGD systems. Flue gas
can be desulfurized by nonregenerable
throwaway systems, (which result in
FGD wastes) or by regenerable systems
(which produce a saleable product—
sulfur or su If uric acid). Operational non-
regenerable FGD systems are currently
predominated by wet scrubbing tech-
nology; however, some dry FGD scrub-
bing systems were becoming opera-
tional in 1982-1983. The principal types
of systems used in utility power plants
are based on direct limestone, direct
lime, alkaline fly ash, dual alkali, and
lime- or sodium-based dry FGD sys-
tems.
Some projections on the generation
of coal ash and FGD wastes [together,
these are designated as flue gas clean-
ing (FGC) wastes] in the U.S. are pre-
sented in Table 1. Most of the coal ash
and all of the FGD wastes generated are
sent to disposal. Considering the ex-
pected increase in coal consumption in
the U.S., this is likely to be the case for
many years. Utilization of FGC waste is
expected to grow but at a slower rate
than FGC waste generation. A signifi-
cant fraction of the total coal ash gener-
ated is used for such purposes as soil
stabilization, ice control, and as ingredi-
ents in cement, concrete, and blasting
compounds; however, there is currently
no utilization of FGD wastes in the U.S.
Table 1. Projections of FGC Waste Gener-
ation by Utility Plants in the
United States (1980-1995)
Waste Generation
(106 Metric tons/yr)
Waste Type 1980
1985
1995
Coal Asha
FGD Wastes"
TOTAL
62.4
8.6
71.0
(78.3)°
83.2
26.9
110.1
(121.4)c
110.0
48.6
158.6
(174.8)c
'Coal ash quantities are shown on a dry basis.
''FGD waste quantities are shown on a wet basis
(50% solids).
CW6 tons/year.
On balance, disposal will continue to be
the major option for FGC waste man-
agement in the U.S. for the foreseeable
future.
Currently, all FGC waste disposal is
on land. At-sea disposal may be a future
alternative if it can be practiced under
environmentally and economically ac-
ceptable conditions. The principal
methods of disposal on land are: pond-
ing, landfilling (including disposal in
surface mines), and interim ponding fol-
lowed by landfilling. Table 2 presents
data on current practices based on data
obtained on 176 plants.
Ponding of FGC waste is more widely
practiced than any other disposal
method. Ponding can be employed for a
wide variety of coal ash and FGD wastes
including chemically treated FGD
wastes. Ponds can be designed based
on diking or incision, but the construc-
tion of dams or dikes for ponds is usu-
ally expensive. In the future, particularly
if chemical treatment of FGD wastes is
widely practiced, ponding will probably
be limited to sites that would involve
minimal construction of dams or dikes.
One exception could be a special case of
wet ponding—FGD gypsum "stacking."
In this case, gypsum slurry from a
forced oxidation system would be piped
to a pond and allowed to settle, and the
supernate recycled. Periodically the
gypsum would be dredged and stacked
around the perimeter of the pond, thus
building up the embankments.
Landfilling of FGC waste is also
widely practiced, and can involve one or
more of a variety of handling operations
prior to the disposal operation. For ex-
ample, bottom ash is almost always
sluiced from the plant, so it must be de-
watered before it is transported. De-
watering must also be applied to fly ash
that is sluiced from the plant or is wet-
scrubbed from the flue gas—with or
without significant quantities of S02
Wet FGD waste must also be dewateret
via thickening, vacuum filtration, and, i
necessary, blending with dry fly ash fo
stabilization or other chemical treat
ment ("fixation") additives such a;
lime. On the other hand, fly ash slatec
for landfill is typically transported di
rectly from the plant in a dry state, witt
only enough moisture added as re
quired for dust control and compactior
in the landfill. Wastes from a spra^
dryer FGD system can also be trans
ported directly; during this project
commercial operation of these systems
on utility boilers was just beginning.
In a landfill disposal site, the wastes
are spread on the ground in 0.3 to 1 m (1
to 3 ft) lifts and compacted by wide-
track dozers, heavy rollers, or othei
equipment. Layering proceeds in 0.3 to
1 m lifts in segments of the site. The ul-
timate height of a disposal fill is site
specific, but can range from 10 m (30 ft)
to as high as 76 m (250 ft). A properly
designed and operating dry impound-
ment system can potentially enhance
the value of the disposal site after
termination, or at least permit post-
operational use.
Mine disposal is a variation of landfill-
ing that is receiving increased attention.
Surface coal mines, particularly those
serving "mine-mouth" plants, offer the
greatest capacity and economic attrac-
tiveness for disposal of wastes from
power plants. Since the quantity (vol-
ume) of FGC wastes produced is consid-
erably less than the amount of coal
burned, many mines would have the ca-
pacity for disposal throughout the life of
the power plant. Several plants, particu-
larly in the Plain States (e.g., North
Dakota), have practiced this disposal
method in recent years.
Interim pond/landfill has been an im-
portant waste disposal method in the
past, but is likely to decline in impor-
tance in the future, particularly since dry
ash handling and disposal is being
more widely practiced.
Site Selection and Test Plan
Preparation
Candidate Site Selection Pro-
cess
The overall objective of the candidate
site selection process was to evaluate
available data on coal-fired power
plants and recommend a number of
candidate and backup sites. The selec-
tion process consisted of two steps.
-------
First, the contiguous 48 states were
divided into 14 physiographic regions,
and the plants in each region were
screened to develop a list of plants that
would be suitable for consideration as
candidate and backup sites. A total
target of 25 to 30 sites, including 18 can-
didate and 7 to 12 backup sites, was de-
sired. Based on an assessment of
present and future FGC waste disposal
practices, a preliminary distribution of
the targeted number of candidate sites
in each region was agreed upon. In
screening selections, the investigators
remained cognizant of the targeted
number in each region, but were not ab-
solutely limited by that number. The at-
tempt was to choose desirable plants in
Table 2. Current FGC Waste Disposal Methods Utilized at Utility Coal-Fired Power Plants in
the U.S. (Data Base: 176 Plants > 200 MW)"
Number of Plants
Type of Waste
Pond" Landfill' Interim Pond/Landfillc
Fly ash only
Bottom ash only
Combined fly and bottom ash
FGD waste only
Mixed fly ash and FGD waste
Mixed bottom ash and FGD waste
Mixed fly ash and FGD waste (stabilized)
Mixed fly ash, bottom ash, and FGD waste
18
29
69
5
7
1
2
2
46
13
9
-
7
—
6
1
6
29
16
-
-
1
-
1
"Coal-fired plants on which data were available (s:80% of their power generated from coal in 1977) which
have generating capacities 2:200 MW with the exception of four plants employing FGD systems. Figures
represent the number of plants at which each waste type/disposal method is practiced. (Note: Many plants
utilize more than one method.)
^Includes direct ponding and interim/final ponding methods.
includes managed and unmanaged fills and mine disposal.
as many regions as possible. A total of
26 plants in all the regions emerged
from this filtration process.
Second, these 26 were then ranked in
iterative group discussions leading to
the nomination of 18 as candidate sites
and the remainder as backup sites.
Final Selection Process
The candidate and backup sites were
then subjected to a more detailed evalu-
ation. These evaluations included one
or more detailed site visits by engineer-
ing, environmental, and hydrogeologic
specialists assigned to the project. Their
findings, together with mid-course eval-
uations that were continuously taking
place, supported an iterative process
that resulted in the selection of the final
six sites. Table 3 provides overall infor-
mation on the final six sites that were
selected for evaluation under this pro-
ject; Figure 1 indicates the site loca-
tions.
Test Plan Preparation
Detailed test plans providing back-
ground information on each of the sites,
together with a description of the pro-
Table 3. Waste Disposal Sites Selected for Evaluation
High Priority Issues
Under Study
Plant (Utility)
Allen
(Duke Power)
Elrama
[Duquesne Light
(waste disposal
by Conversion
Systems, Inc.)]
Dave Johnston
(Pacific P&L)
Sherburne
County
(Northern
States Power)
Powerton
(Commonwealth
Edison)
Smith
(Gulf Power)
Nameplate
State (County) (MW)
N. Carolina 1155
(Gaston)
Pennsylvania 310
(Washington)
Wyoming 730
(Converse)
Minnesota 1458
(Sherburne)
Illinois 1786
(Tazewell)
Florida 340
(Bay)
Startup Date
(mo/yr)
Plant (FGD)
-/57
6/52
(10/75)
-/59
5/76
-/72
6/65
Waste Site Under Study _ _ .
firniinri Gill-faro
Waste Type
Combined fly
and bottom ash
Stabilized
FGD waste
Combined fly
and bottom ash
Fly ash
Fly ash/FGD
Combined fly
and bottom ash
Combined fly
and bottom ash
Disposal Water Water
Method' Quality Quality
Pond (UL) X X
Landfill X X
(UL; offsite)
Landfill
(UL; offsite)
Landfill X —
(UL)
Pond (CD X —
Landfill X X
(AL)
Pond (UL) X X
Employment
of a
Potentially
Mitigative
Practice
X
X
X
X
X
X
'UL = Unlined.
CL = Clay-Lined.
AL = Artificially Lined (Poz-0-Tec).
-------
Dave Johnston
Sherburne County
Elrama
—-»——-i r~^^ s •>«k x*
/ —«Xxr-'^*>C
i AV-T- <. /^
' / ' » X -X
VI i JUT
Figure 1. Location of waste disposal sites selected for evaluation.
posed program of site development,
physical and chemical sampling, and
analysis and engineering/cost assess-
ments, were developed. The test plans
were reviewed by EPA and the utility
involved, and their comments were in-
corporated. The finalized test plans
guided the work at each site.
Site Development and Physical
Testing
After approvals from the utility and, in
some cases, from state regulatory agen-
cies, site development was begun. Site
development and physical testing were
governed by procedure manuals devel-
oped for this project. The activities in-
volved in site development included the
drilling of borings; excavating test pits;
collecting waste, soil, and water sam-
ples; conducting field permeability
tests; installing ground water monitor-
ing wells and piezometers; and docu-
menting each activity. These activities
took place at each of the six sites in time
periods of 2 to 4 weeks. Table 4 indi-
cates the timing under which the six
sites were developed and the extent of
the activities at each site. The table also
gives the number of physical tests per-
formed; i.e., laboratory soil classifica-
tion and permeability tests on waste
samples from the sites. Preliminary
water balances were also developed for
each site.
Chemical Sampling and Analy-
sis
At each site, a program of chemical
sampling and analysis was undertaken.
This program included characterization
of waste, water, and soil samples ob-
tained from site development, and
ground water well and (in some cases)
surface water samples subsequently
obtained from a series of visits sched-
uled to correspond to relatively wet, rel-
atively dry, and intermediate periods for
each site. Table 5 summarizes the sam-
pling and analysis program.
Chemical samples are subjected to
several types of analyses: ion chro-
matography (1C) for six anions; induc-
tively coupled argon plasma emissions
spectroscopy (ICAP) for 26 metals; and
atomic absorption spectroscopy (AA)
for selected metals. As shown in
Table 5, these types of analyses were
performed on a mix of solid and liquid
samples for each site. In addition, a
limited number of experiments were
performed to assess the attenuative ca-
pacity of various soils obtained at the
sites. Furthermore, during the initial
phase of this project, 23 grab samples of
wastes from 18 plants were obtained
and analyzed using the EPA Extractor
Procedure (EP); results from these tests
are summarized in Table 6. Furthei
details on these tests, as well as results
of radioactivity measurements, are in-
cluded in the final report of the project.
Site-Specific Environmental
Evaluations
The data and information from site
development and sampling/analysis
were subjected to environmental ef-
fects evaluation throughout the proj-
ect. The individual site evaluations
were developed in five steps: (1) a re-
view and evaluation was made of
available background information on
the disposal operation and its environ-
mental setting; (2) present disposal-
related water quality effects were
identified and described based on
evaluation and measured information
developed in this project; (3) apparent
cause/effect relationships were hy-
pothesized to explain the findings at
the sites; (4) potential future ranges of
water quality effects were considered
to the extent that suitable data were
available; and (5) industry-wide impli-
cations of the findings at the individ-
ual sites were considered in the
generic assessment, discussed later in
this summary.
Environmental evaluation of all six
sites has generated a significant
amount of data and information. The
following general items can be re-
ported:
1. Data suggest that no major ad-
verse environmental effects have
occurred at any of the sites. For ex-
ample, data from wells downgradi-
ent of the disposal sites suggest
that the contribution of waste
leachate to the ground water has
resulted in concentrations of
chemicals less than the primary
drinking water standards estab-
lished by EPA.
2. The results from the sites are inter-
nally consistent. In other words,
the analyses of samples taken on
different dates at the same loca-
tions are very similar.
3. The total integrated evaluation of
data from site development, site
water balances, physical testing of
wastes samples, and chemical
sampling and analysis is providing
a large significant data base to ex-
plain many of the environmental
effects that can result from coal
ash and FGD waste disposal.
-------
Table 4.
Plant
Allen
Elrama
Johnston
Sherco
Powerton
Smith
Table 5.
Site
Allen0
Elrama
Sherco
Smith
Powerton
Summary of Site Developme
Date
Development
Completed
(mo/yr)
07/87
03/87
05/87
08/81
77/87
72/87
•nt/Physical Testing
Number of
Borings Wells
20 20
20 16
14 12
13 11
11 9
25 24
Test
Pits
2
4
10
-
1
-
Soil
Samples
152
199
154
178
112
146
Number of
Laboratory Physical Tests
Unified Soil
Classification
Series (USCS) Permeability
18 4
17 13
12 7
20 6
30 8
15 8
Summary of Chemical Sampling and Analysis Program
Trip 1
Samples3
Trips 2, 3, and 4
wells wells and
ash solids surface waters
interstitial liquors
soils
wells
waste solids
soil
waste extracts
wells
waste interstitial
liquors
waste solids
liner solids
liner liquor
soil solids
soil extracts
liquids
waste solids
interstitial waste
liquors
soil
soil liquors
wells
waste solids
Dave Johnston wells
waste solids
waste extracts
soils
wells, lysimeters,
surface waters
wells and
surface liquors
wells and
surface waters
wells and
surface waters
wells and
surface waters
Trip 1
ICAP
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1C
X
X
X
X
X
X
X
X
X
X
X
X
X
Analyses13
Trips 2, 3, and 4
As/Se Field Data Other
X X
X
X
X
X X
X Xd
X
X X
X
X X
X X
X X
X
'Samples obtained during site development and subsequent sampling and analysis trips.
^Analyses performed are abbreviated as follows:
ICAP—Ag, Al, B, Ba. Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Si, Sr, Th, Ti, V, Zn, Zr. (Does not include B, Ba, and Si for solids.)
IC—F-, CI-, NOj. SOJ, Br~, PO|-.
As/Se—either or both on selected samples.
Field Data—ground water level, pH, dissolved oxygen, conductivity, temperature.
cOther samples were obtained (boiler cleaning wastes). Analysis was limited to ICAP, pH, and bromate.
^Includes solids characterization for SOj~, total oxidizable sulfur, slurry pH, acid insolubles.
-------
A brief account of the results at each
of the sites is presented below.
Allen—The results indicate:
1. Leachate generated within the ash
ponds contain elevated (over back-
ground) concentrations of several
waste-related chemical con-
stituents (e.g., boron, sulfate, cal-
cium, arsenic). However, the sur-
rounding soils have attenuated
significant fractions of leachate
constituent contaminants within
the immediate vicinity of the
ponds.
2. Leachate water from the upgradi-
ent portions of the ash ponds has
not moved sufficiently to create
steady-state concentrations of
unattenuated constituents (e.g.,
sulfate) in downgradient wells.
However, concentrations of these
constituents are expected to only
reach or barely exceed secondary
drinking water standards (e.g., for
sulfate, 250 ppm).
Elrama— The results indicate:
1. Prior to disposal of FGC wastes,
much of the site was contaminated
by acid mine drainage, resulting in
low pH (4.5 to 5) and nigh concen-
trations of chemical constituents
(e.g., about 2000 ppm sulfate) in
the ground water.
2. The landfill and runoff collection
ponds may serve as potential
sources of some constituents via
leachate and overflow, including
chloride and calcium (both at
about 500 ppm). However, neither
chloride nor calcium is at a level to
cause major concern. In addition,
an elevated level (about 0.2 ppm)
of arsenic was measured at one
waste/soil interface lysimeter;
however, it does not appear to be a
general problem. In any event,
substantial attenuation of arsenic
by soils at the site is expected.
3. The relative absence of elevated
levels of these waste-related con-
stituents in downgradient ground
water may be explained by the rel-
atively short time the fill has been
in operation (4 years), chemical/
physical attenuation phenomena
(including the effects of the treat-
ment/disposal process), or a com-
bination of these factors.
4. The landfill does not appear to
alter significantly the local concen-
trations of some constituents
(such as sulfate) potentially avail-
able from both mine drainage and
FGC wastes.
Dave Johnston—The results indicate:
1. The water balance and estimates
of plume arrival time indicate that
the widespread measurement at
the site of what might elsewhere
be considered elevated chemical
constituent levels (e.g., sulfate,
about 1000 ppm) is not due to the
waste landfills. The estimates of
plume arrival time for the periph-
eral wells downgradient from (not
directly under) the active landfill
are in excess of 100 to 300 years
considering only travel time in the
saturated zone. Travel time from
the 20-year old inactive landfill to a
much closer (to the landfill) down
gradient well is estimated to be ir
excess of 20 years, accounting fo
both unsaturated and saturatec
zone travel.
2. Most of the "elevated" measure
ments reflect pervasively high
background levels characteristic 01
highly mineralized ground water ir
many western settings. However
lower measured values (e.g.
sulfate about 100 ppm) at one
background and one periphera
well indicate that even in highly
mineralized arid areas there ma\
be areas of good water quality that
require protection in waste dis-
posal site planning and manage-
ment.
Sherco—The results indicate:
1. Leachate movement from the
ponds has thus far been suffi-
ciently retarded by the clay liner to
preclude development of signifi-
cant elevations of chemical con-
stituents in the leachate at down-
gradient wells.
2. A waste-related influence is re-
flected in the slightly elevated
levels (of boron and sulfate) mea-
sured in the peripheral/downgra-
dient wells to the west and south-
west, but it is not clear whether
this is due to past leakage from
the sheet piling/conduit area, to
leachate that has moved through
the liner, or to a combination of
these two sources.
3. Because of the pervious soils in the
area of the site, significant in-
Table 6. Summary of Results of Extraction Procedure (EP) Tests of 20 Fly Ash and 3 FGD Waste Grab Samples
Metal
Overall Range Observed, \t.g/l
Fly Ash
FGD Waste
Interim Primary Drinking
Water Standards8, p.g/1
Ratio of Range Observed to Standards
Fly Ash
FGD Waste
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
<2 -410
< 100 - 700
<2 - 193
<8 - 930"
<3 - <36
<2
<2-340
<1
<2 -
<150-
<2-
<11-
<5
<2
8-
<1
65
230
20
26b
49
50
1000
10
50b
50
<1
10
50
<0.04
<0.1
<0.2
<0.16
<0.06
<
<0.2
- 8.2
- 0.7
- 19.3
- 18.6
-0.72
1
-34
<0.02
<0.04 -
<0.15-
<0.2 -
<0.22 -
0.1
<1
0.8 -
1.30
0.23
2
0.52
4.9
<0.02
"These standards are "...for use in determining whether solid waste disposal activities comply with ground water criteria." Standards included, but not measured
in these tests, are for fluoride: 1400-2400 \i.g/l (depending on temperature), and for nitrate (as N): 10,000 \t.g/l.
bAn amendent to the chromium criteria for the EP revises it from total chromium to CrfVI); since the total chromium values were measured by atomic absorption
(AA), the measured ranges represent upper limits for CrIVI) in the samples.
-------
creases in concentrations of major
soluble species are expected to oc-
cur in downgradient wells in the
next few years. Secondary drink-
ing water standards are expected
to be exceeded in these wells.
However, any effects of movement
of these species off-site will be mit-
igated (diluted) by the Mississippi
River, which flows by the plant.
4. The higher concentrations of
waste parameters in FGC pond su-
pernatant versus underlying waste
interstitial waters may be due to
two factors: (1) the conversion by
the utility to a system involving re-
cycle of the FGC waste transport
water would have resulted in in-
creased concentrations of chemi-
cals in the water; and (2) the evap-
oration of water in the pond would
also increase remaining chemical
concentrations.
Powerton—The results indicate:
1. Although the completed landfill
was supposed to have a 0.25 m
(8 in.) Poz-0-Tec liner, during the
coring operation a general ab-
sence of liner material was ob-
served. This observation is consis-
tent with the practical difficulty of
achieving uniform placement of
such a relatively thin layer of soil-
like material over a large area. Cur-
rent engineering practice suggests
that a minimum thickness of 0.45
to 0.60m (18 to 24 in.) of liner
placement would be desired to en-
sure full effectiveness.
2. The surface water analytical re-
sults for Lost Creek are consistent
with the water balance calcula-
tions. Both sets of results indicate
that the stream has adequate as-
similative/dilution capacity to
lower current concentrations of
chemical constituents in leachate
reaching Lost Creek to insignifi-
cant levels.
3. The results also suggest that the
stream, if an effective ground
water flow divide, may limit the ex-
tent of further downgradient
ground water contamination by
the waste plume.
4. The general lack of elevated trace
metal concentrations in ground
water suggests that a combination
of chemical attenuation (especially
for chromium and lead) and dilu-
tion is preventing the release of
significant quantities of these ele-
ments and/or elevation to signifi-
cant concentrations at downgradi-
ent locations.
5. Elevated concentrations of nitrate
at various sampling locations at
the site can be attributed to local
agricultural and urban nonpoint
source activities, and not the coal
ash landfill.
Smith—The results indicate:
1. There appears to have been a
steady state achieved between the
concentrations of soluble species
in the pond and in the immediately
adjacent downgradient areas.
2. There appears to be little or no
chemical attenuation of the major
tracer species such as calcium and
strontium, but rather a progressive
reduction in concentrations in the
downgradient direction. This is
consistent with what would be ex-
pected due to admixing of leachate
with the greater amounts of dilu-
tion water.
3. The use of high total dissolved
solids Bay water in the pond for
makeup and its presence in adja-
cent downgradient areas create a
situation where little incremental
effect is detectable from such typi-
cal ash pond "tracer" species as
sulfates, chlorides, and boron.
Generic Environmental Evalua-
tion of Coal Ash and FGD
Waste Disposal
The environmental effects of solid
waste disposal practice are determined
by three factors: waste type, disposal
method, and the environmental setting.
The data base from this project and
other related projects suggests that
present and future practices of coal ash
and FGD waste disposal may be effec-
tively evaluated using a matrix consist-
ing of four waste types, three disposal
methods, and five environmental set-
tings.
The four waste types are:
1. Fly ash or fly ash admixed with
other materials. A significant body
of literature suggests that most
trace metals available for leaching
from utility solid wastes may be
associated with those containing
fly ash. Thus this category of
wastes includes fly ash or fly ash
mixed with bottom ash and fly-
ash/bottom-ash/FGD-waste mix-
tures (excluding chemically
treated FGD wastes; see item 3,
below).
2. Non fly ash materials. This cate-
gory includes bottom ash {or
boiler slag) and FGD wastes that
are disposed of separately from fly
ash (including forced oxidation
wastes). This category usually con-
tains lesser concentrations of trace
metals, but can result in higher
concentrations of major species
(e.g., chlorides from FGD waste).
3. Stabilized FGD wastes. FGD
wastes may be processed or stabi-
lized for full-scale disposal by a va-
riety of processes; the processes
presently in commercial practice
involve the addition of lime and fly
ash, or processed slag. Lime/fly
ash stabilization for landfill dis-
posal is presently practiced at
some power plants and is ex-
pected to grow in importance. Pro-
cessed FGD wastes are a separate
category because of the differ-
ences in their physical and chemi-
cal properties created by the stabi-
lization process.
4. Dry FGD wastes. Several dry FGD
systems are expected to come into
commercial use over the next
3 years. It appears that calcium-
based dry FGD systems are antici-
pated to grow more than sodium-
based systems. By either process,
dry FGD systems provide a com-
bined waste (containing fly ash
and the sulfur compound) in a rela-
tively dry form that is likely to be
sent for disposal to a managed
landfill. The physical and chemical
properties of these wastes are ex-
pected to be different from the
other categories discussed above;
additionally, there is a relative lack
of even limited field scale informa-
tion on their leaching characteris-
tics to date.
Three disposal methods for coal ash
and FGD wastes are in practice and ex-
pected to continue in the future:
(Dpond disposal; (2) interim ponding
followed by landfill disposal; and
(3) landfill disposal (including disposal
in mines, which is considered a special
case of landfill ing).
Three of the five environmental set-
tings for solid waste disposal are based
on major differences in climate and hy-
drogeology: (1) coastal areas, specifi-
cally where surface water and ground
water are influenced by the ebb and
flow of tides; (2) arid areas, characteris-
tic of much of the western U.S., where
net evaporation generally exceeds pre-
-------
cipitation by a significant margin; and
(3) interior areas, characteristic of the
non-coastal portions of the eastern U.S.
where there tends to be more of a bal-
ance between precipitation and evapo-
ration and where permanent surface
water bodies are in such abundance as
to be near many disposal sites.
Further evaluations during this proj-
ect suggested that a further breakdown
of two special categories would be use-
ful because of their singificant charac-
teristics: (1) arid areas in the west where
ground and surface waters are very
highly mineralized, and (2) interior
areas subject to acid mine drainage.
Both these settings and the coastal set-
ting tend to have water quality charac-
teristics that can potentially show less
of an incremental effect from coal ash
and FGD waste leachates. This is be-
cause the waters in these areas already
contain a number of chemicals found in
the leachate.
Table 7 is a matrix of waste types,
methods of disposal, and environmen-
tal settings and indicates combinations
for which field-scale and other informa-
tion is available. Sources of data and
information other than this study in-
cluded the Utilities Solid Waste Activi-
ties Group (USWAG), the Electric Power
Research Institute (EPRI), and the De-
partment of Energy (DOE). DOE is cur-
rently sponsoring a study of disposal of
FGD wastes in a surface mine; the study
was originally sponsored by EPA. As is
clear, some information is available for
most of the combinations that are being
practiced today or are likely to be prac-
ticed in the future.
It appears that, on balance, technol-
ogy exists for environmentally sound
disposal of coal ash and FGD wastes
using any of the modes of disposal. Po-
tential environmental effects are highly
site and system specific. For some com-
binations of waste types, disposal
methods, and environmental settings,
mitigative measures must be taken to
avoid ground water and/or surface
water contamination. However, site
specific application of good engineering
design and practice can mitigate most
potentially adverse environmental ef-
fects of waste disposal.
Engineering/Cost Evaluations
The first major efforts in the engineer-
ing/cost evaluations involved develop-
ment of site-specific conceptual engi-
neering designs and costs (capital and
first year operating and maintenance
costs) for the current solid waste han-
dling and disposal operations at the six
study sites. To facilitate the ultimate use
Table 7. Summary of Information Available for Combinations of Waste Types, Disposal Methods, and Environmental Settings
Ponding Interim Ponding/Landfilling Landfilling
Setting
Coastal
Fly
Ash*
X
Smith^
Non-Fly
Asht>
P
Processed Dry
FGD FGD
NA NA
Fly
Ash'
X/Pd
Chisman
Cr.
(USWAG)
Non-Fly
Ash*
P
Processed
FGD
P
Dry
FGD
NA
Fly
Ash>>
P
Non-Fly
Ash1'
P
Processed
FGD
P
Dry
FGD
pe
Arid Western—
Not Highly Mineralized
Arid Western—
Highly Mineralized
NA NA
NA NA
NA
X
Dave
Johnston;
Milton
Young
(DOE/EPA)
pe
Interior—
Wot Highly Acidic
X
Allen,
Sherco,
Michigan City
(USWAG),
Wallingford
(USWAG)
X NA X/P<>
Bruce Bailly
Mansfield (USWAG)
NA
X
Powerton,
Zuellinger
(USWAG)
Hunts
Brook
(USWAG)
Dunkirk
(DOE)
X
Conesville
(EPRI/USWAG)
pe
Interior—
Highly Acidic
(mine drainage)
NA
NA
X
Elrama
Notes: a. Includes co-disposal of fly ash with other wastes.
b. Includes FGD wastes without fly ash and bottom ash.
c. Plants for which data and information are obtained are listed in their appropriate positions.
d. Either the interim pond or landfill aspect of operation studied at field scale, but not both.
e. Laboratory data only.
Key: X = Data available from full-scale field studies.
P = Data available from laboratory and/or limited-scale field studies for projection purposes.
NA = Matrix combination not applicable due to lack of present and future practice.
8
-------
of the cost data, the estimates were de-
veloped by breaking down the waste
handling and disposal operations into
five modules: (1) raw material handling
and storage; (2) waste processing and
handling; (3) waste storage; (4) waste
transport; and (5) waste placement and
disposal (including site monitoring and
reclamation).
Based on the site-specific cost esti-
mates and other studies by TV A, EPRI,
and other organizations, generic capital
and O&M cost estimates were then pre-
pared for individual modules compris-
ing waste handling and disposal for coal
ash and FGD wastes. Tables 8 and 9
summarize results of this effort.
The range of costs given represents
variations in specific plant operations as
well as variations in the several cost es-
timates used in preparing these esti-
mates. For example, the higher end of
the range for FGD waste handling/pro-
cessing might include thickening, vac-
uum filtration, and mixing with lime and
fly ash, while the lower end could repre-
sent a simpler operation with little or no
processing. Figures 2 and 3 show the
Table 8. Generic Capital Cost Estimates for FGC Waste Disposal ILate 1982 Dollars)"
estimates for the FGD waste handling/
processing "module." Similar figures
for all the modules listed in Tables 8 and
9 are included in the final report for the
project.
Conclusions
Results from this 3-year study of dis-
posal of coal ash and FGD wastes from
coal-fired electric generating plants pro-
vide major technical guidance for regu-
latory bodies and the utility industry.
However, results from field studies of
this type are limited, and predictive
Capital Cost Range
($/kW)
Plant Size (MW)
Module
Submodule
250b
500"
Fly ash storage
Dry
4.7-8.8
4.2-7.7
"Engineering News Record (ENR) Index = 3937.77 (1913 - 100)
= 365.97 {7967 - 1001
Relationship between plant size and waste generation for typical case:
Annual Waste Generation Rate
(dry metric tons/MW of Plant Generating Capacity I
Fly Ash
Bottom Ash
FGD Waste
"Typical Case" Assumptions
Coal Properties:
Load Factor:
Heat Rate:
S02 Removal:
Lime Stoichiometry:
Fly Ash/Bottom Ash Ratio:
cAssumed FGD System: Wet Lime Scrubbing
280
70
240
2% S, 13% Ash, 10,500 Btu/lb (24.4 x 70« MJ/kg)
70%
10,250 Btu/kWh (10.8 x 70S MMWh)
90%
1.1
80/20
1000"
3.7-6.8
200Qb
Fly ash handling/processing
Wet handling w/o recycle
Wet handling w/recyc/e
Dry handling
2.3-4.3
3.7-6.8
2.2-4. 1
1.9-3.5
3.0-5.5
1.8-3.3
1.5-2.9
2.4-6.4
1.4-2.7
1.3-2.3
1.9-3.6
1.2-2.2
3.2-5.9
Fly ash transport
Fly ash placement/disposal
Bottom ash handling/processing
Bottom ash transport
Bottom ash placement/disposal
Raw material handling/storage
FGD waste handling/processing0
FGD waste transport
FGD waste placement/disposal
Wet sluicing
Dry trucking
Unlined pond
Landfill
Wet handling w/o recycle
Wet handling w/recycle
Wet sluicing
Dry trucking
Unlined pond
Landfill
Dry (lime and fly ash)
Wet handling
Wet sluicing
Dry trucking
Unlined pond
Landfill
3.5-6.4
0.3-0.5
15.1-27. 8
4.3-8. 1
2.2-4.1
2.5-4.6
3.0-5.6
0.2-0.4
6.4-11.8
1.3-2.4
2.4-4.5
18.1-33.6
0.7-1.3
0.4-0.7
10.0-18.6
4.1-7.6
2.7-5.1
0.3-0.6
12.9-23.9
3.3-6. 1
1.7-3.2
2.0-3.7
2.4-4.5
0.2-0.3
5.1-9.6
1. 1-2.0
2.1-3.9
15.2-28.3
0.5-1.0
0.3-0.6
8.9-16.6
3.3-6.2
2.2-4.0
0.3-0.5
1 1.0-20.5
2.5-4.7
1.3-2.5
1.6-3.0
1.9-3.6
0.1-0.2
4.2-7.7
0.9-1.6
1.9-3.4
12.8-23.8
0.4-0.8
0.3-0.5
7.9-14.7
2.7-5.0
1.7-3.2
0.2-0.5
9.4-17.5
1.9-3.6
1.0-1.9
1.3-2.4
1.5-2.8
0. 1-0.2
3.4-6.2
0.7-1.3
1.6-3.0
10.8-20.0
0.4-0.7
0.3-0.5
7.0-13.1
2.2-4.0
-------
tools (e.g., computer models) for evalu-
ating interactions between these wastes
and site-specific hydrogeologic systems
are, in many cases, inadequate. For this
reason, additional efforts sponsored by
industry are currently underway to de-
velop more sophisticated tools for pre-
dicting and analyzing the potential envi-
ronmental effects of coal ash and FGD
waste disposal.
Table 9. Generic Annual Cost Estimates for FGC Waste Disposal (Late 1982 Dollars)3
Annual Cost Range
($/dry metric ton)
Plant Size (MW)
Module
Fly ash handling/processing
Fly ash storage
Fly ash transport
Fly ash placement/disposal
Bottom ash handling/processing
Bottom ash transport
Bottom ash placement/disposal
Raw material handling/storage
FGD waste handling/processing0
FGD waste transport
FGD waste placement/disposal
Submodule
Wet handling w/o recycle
Wet handling w/recycle
Dry handling
Dry
Wet sluicing
Dry trucking
Unlined pond
Landfill
Wet handling w/o recycle
Wet handling w/recycle
Wet sluicing
Dry trucking
Unlined pond
Landfill
Dry (lime and fly ash)
Wet handling
Wet sluicing
Dry trucking
Unlined pond
Landfill
250b
2.5-4.6
3.7-6.8
2.5-4.7
3.3-6.1
4.2-7.6
1.7-3.1
11.5-21.3
7.0-13.0
11.3-21.0
12.3-22.8
9.2-17.1
3.4-6.3
9.2-17.1
5.4-10.0
4. 1-7.6
17.2-31.9
1.1-2.1
2.9-5.4
8.5-15.8
4.0-7.5
500"
1.0-3.7
2.9-5.4
2. 1-3.9
3.0-5.6
3.2-5.9
1.5-2.8
9.1-16.8
5.6-10.5
9.0-16.7
10.3-19.1
7.3-13.5
2.8-5.2
7.9-14.6
4.7-8.8
3.7-6.7
13.8-25.5
0.9-1.7
2.3-4.3
6.7-12.4
3.4-6.3
1000"
1.6-3.0
2.3-4.3
1.7-3.2
2.8-5.2
2.5-4.7
1.3-2.5
7.2-13.5
4.6-8.5
6.9-12.8
8.4-15.7
5.6-10.3
2.2-4.1
6.5-12.1
4. 1-7.6
3.4-6.2
11.0-20.5
0.7-1.3
1.8-3.3
5.2-9.7
2.8-5.3
2000"
1.3-2.3
1.8-3.6
1.5-2.7
2.5-4.7
2.0-3.7
1.2-2.2
5.7-10.5
3.7-6.9
5.3-9.9
6.9-12.8
4.3-7.9
1.8-3.3
5.4-10.0
3.5-6.5
3.0-5.6
8.8-16.4
0.6-1.1
1.4-2.6
4.1-7.6
2.4-4.4
'Engineering News Record (ENR) Index = 3937.77 (7973 - 100)
= 365.97 (7967 - 700)
bRelationship between plant size and waste generation for typical case:
Annual Waste Generation Rate
(dry metric tons/MW of Plant Generating Capacity)
Fly Ash
Bottom Ash
FGD Waste
280
70
240
"Typical Case" Assumptions
Coal Properties:
Load Factor:
Heat Rate:
S02 Removal:
Lime Stoichiometry:
Fly Ash/Bottom Ash Ratio:
'Assumed FGD System: Wet Lime Scrubbing
2% S, 13% Ash, 70,500 Btu/lb 124.4 x 706 MJ/kg)
70%
10,250 Btu/kWh (10.8 x 70« MJ/kWhl
90%
1.1
80/20
10
-------
50,000
45,000
^ 40,000
-------
C. Santhanam, A. Balasco. I. Bodek, andC. Cooper are with Arthur D. Little, Inc.,
Cambridge, MA 02140; J. Humphrey is with Haley andAldrich, Inc., Cambridge,
MA 02142; and B. Thacker is with Geologic Associates, Inc., Knoxville, TN
37922.
Julian W. Jones is the EPA Project Officer (see below).
The complete report, entitled "Full-scale Field Evaluation of Waste Disposal from
Coal-fired Electric Generating Plants" (Set Order No. PB 85-228 047/AS; Cost
$157.00, subject to change), consists of six volumes:
"Volume I. Sections 1 through 5," (Order No. PB 85-228 054/AS; Cost
$29.50, subject to change}.
"Volume II. Sections 6 Through 9," (Order No. PB 85-228 062/AS; Cost
$22.00, subject to change).
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$34.00, subject to change).
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Volume V. Appendix F," (Order No. PB 85-228 096/AS; Cost $41.50,
subject to change).
Volume VI. Appendices G Through I,"(Order No. PB 85-228 104/AS; Cost
$17.50, subject to change).
The above reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U. S. En vironmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
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