& EPA 

United States 

Environmental Protection 

Agency 

Research and Development 

Air and Energy Engineering 

Research Laboratory 

Research Triangle Park NC 27711 

EPAl600/S7-85/028 Aug. 1985 

Project Summary 

Full-Scale Field Evaluation of 

Waste Disposal from CoalFired Electric Generating 

Plants 

Chakra J. Santhanam, Armand A. Salasco, Itamar Sodek, 

Charles S. Cooper, John T. Humphrey, and Sarry Thacker 

This project summary describes results 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 involved characterization of wastes, environmental data gathering, evaluation 

of environmental effects, and engineering/cost evaluations of disposal practices at six sites around the country. Results of the study provide technical 

background data and information to 

EPA, state and local permitting officials, 

and the utility industry for implementing environmentally sound disposal 

practices. 

Data from the study suggest that no 

major environmental effects have occurred at any of the six sites; i.e., data 

from wells downgradient of the disposal sites indicate that waste leachate 

has resulted in concentrations of chemicals less than the EPA primary drinking 

water standards. A generic environmental evaluation-based on a matrix 

of four waste types, three disposal 

methods, and five environmental settings (based on climate and hydrogeology)-shows that, on balance, technology exis,s 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 adverse environmental effects. However, 

site specific application of good engineering design and practices can mitigate 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 developed by EPA's Air and Energy Engineering Research Laboratory, Research Triangle Park, Ne, to announce key 

findings of the research project that is 

fully documllntlld in six slIparatll volumlls (SIIII Projllct Rllport ordllring information 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 disposal practices at six sites around the 

country. Results of the study provide 

the technical background data and information needed to help EPA determine 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 Congress required under the 1980 

Amendments to the Resource Conservation and Recovery Act (RCRA), and 

should provide useful technical information to federal, state, and local permitting officials and utility planners on 

methods for environmentally sound 

disposal of coal ash and FGD wastes. 
l" 

Background on Waste Generation/Disposal Methods 

Coal-fired power plants using conventional combustion technology generate two major categories of waste materials: coal ash (fly ash, bottom ash, or 

boiler slag) and FGD wastes are generated 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 treatment and maintenance cleaning 

wastes, general power plant trash, and 

plant sanitary wastes. This project focused primarily on the high volume 

wastes. 

Fly ash from coal-fired utility boilers is 

collected by mechanical collectors andl 

or electrostatic precipitators, fabric filters, or wet scrubbers. By late 1982, approximately 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 productsulfur or sulfuric acid). Operational nonregenerable FGD systems are currently 

predominated by wet scrubbing technology; however, some dry FGD scrubbing systems were becoming operational 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 systems. 

Some projections on the generation 

of coal ash and FGD wastes [together, 

these are designated as flue gas cleaning (FGC) wastes] in the U.S. are presented in Table 1. Most of the coal ash 

and all of the FGD wastes generated are 

sent to disposal. Considering the expected 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 significant fraction of the total coal ash generated is used for such purposes as soil 

stabilization, ice control, and as ingredients in cement, concrete, and blasting 

compounds; however, there is currently 

no utilization of FGD wastes in the U.S. 

2 

Table 1. 

Waste Type 

Coal Asha 

Projections of FGC Waste Generation by Utility Plants in the 

United States (1980-1995) 

Waste Generation 

(106 Metric tons/yr) 

1980 1985 1995 

62.4 83.2 110.0 

FGD Wastesb 8.6 26.9 48.6 

TOTAL 71.0 110.1 158.6 

(78.3)C (121.4)C (174.8)C 

sCoal ash quantities are shown on a dry basis. 

bFGD waste quantities are shown on a wet basis 

(50% solids). 

c106 tons/year. 

On balance, disposal will continue to be 

the major option for FGC waste management 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 acceptable conditions. The principal 

methods of disposal on land are: ponding, landfilling (including disposal in 

surface mines), and interim ponding followed 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 construction of dams or dikes for ponds is usually 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 example, bottom ash is almost always 

sluiced from the plant, so it must be dewatered before it is transported. Dewatering must also be applied to fly ash 

that is sluiced from the plant or is wetscrubbed from the flue gas-with or 

without significant quantities of SO, 

Wet FGD waste must also be dewatere( 

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 transported directly; during this project 

commercial operation of these system~ 

on utility boilers was just beginning. 

In a landfill disposal site, the wastef 

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 othel 

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 impoundment system can potentially enhance 

the value of the disposal site after 

termination, or at least permit postoperational use. 

Mine disposal is a variation of landfilling that is receiving increased attention. 

Surface coal mines, particularly those 

serving "mine-mouth" plants, offer the 

greatest capacity and economic attractiveness for disposal of wastes from 

power plants. Since the quantity (volume) of FGC wastes produced is considerably less than the amount of coal 

burned, many mines would have the capacity for disposal throughout the life of 

the power plant. Several plants, particularly in the Plain States (e.g., North 

Dakota), have practiced this disposal 

method in recent years. 

Interim pond/landfill has been an important waste disposal method in the 

past, but is likely to decline in importance in the future, particularly since dry 

ash handling and disposal is being 

more widely practiced. 

Site Selection and Test Plan 

Preparation 

Candidate Site Selection Process 

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 selection 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 candidate and 7 to 12 backup sites, was desired. 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 absolutely limited by that number. The attempt was to choose desirable plants in 

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 

Table 2. Current FGC Waste Disposal Methods Utilized at Utility Coal-Fired Power Plants in 

the U.S. (Data Base: 176 Plants a: 200 MW)S 

The candidate and backup sites were 

then subjected to a more detailed evaluation. These evaluations included one 

or more detailed site visits by engineering, environmental, and hydrogeologic 

specialists assigned to the project. Their 

findings, together with mid-course evaluations that were continuously taking 

place, supported an iterative process 

that resulted in the selection of the final 

six sites. Table 3 provides overall information on the final six sites that were 

selected for evaluation under this project; Figure 1 indicates the site locations. 

Type of Waste 

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 

Number of Plants 

LandfillC 

46 

13 

9 

7 

6 

1 

Interim PondlLandfillc 

6 

29 

16 

aCoal-fired plants on which data were available (;;;:;80% of their power generated from coal in 1977) which 

have generating capacities ;;;:;200 MW with the exception of four plants employing FGO systems. Figures 

represent the number of plants at which each waste type/disposal method is practiced. (Note: Many plants 

utilize more than one method.) 

Test Plan Preparation 

blncludes direct ponding and interimlfinal ponding methods. 

clncludes managed and unmanaged fills and mine disposal. 

Table 3. Waste Disposal Sites Selected for Evaluation 

Nameplate 

Generating Startup Date Location Capacity (molyr) 

Plant (Utility) State (County) (MW) Plant (FGD) 

Allen N. Carolina 1155 -157 

(Duke Power) (Gaston) 

Elrama Pennsylvania 310 6152 

[Duquesne Light (Washington) (tOn5) 

(waste disposal 

by Conversion 

Systems, Inc.)} 

Dave Johnston Wyoming 730 -/59 

(Pacific P&L) (Converse) 

Sherburne Minnesota 1458 5176 

County (Sherburne) (5176) 

(Northern 

States Power) 

Powerton Illinois 1786 -n2 

(Commonwealth (Tazewell) 

Edison) 

Smith Florida 340 6165 

(Gulf Power) (Bay) 

aUL = Unlined. 

CL = Clay-Lined. 

AL = Artificially Lined fPoz-O-Tec}. 

Detailed test plans providing background information on each ofthe sites, 

together with a description of the proHigh Priority Issues 

UnderStudy 

Employment 

Waste Site Under Study ofa 

Ground Surface Potentially 

Disposal Water Water Mitigative 

Waste Type MethodS Quality Quality Practice 

Combined fly Pond (UL) X X X 

and bottom ash 

Stabilized Landfill X X X 

FGD waste (UL; off site) 

Combined fly Landfill 

and bottom ash (UL; offsite) 

Fly ash Landfill X X 

(UL) 

Flyash/FGD Pond (CL) X X 

Combined fly Landfill X X X 

and bottom ash (AL) 

Combined fly Pond (UL) X X X 

and bottom ash 

3 
j""___ Dave Johnston Sherburne County 

, ... . __ , \ .,h "" ~ , '. \.,..~;!J r-~ 'i~ . __ .-'-'-9 , '~-L' ;-.::.~. - =- ... S ~ : , _ I ,I ; • .r Elrama 

\ ' r .. ·---- , t..:; .. k r· (.~ , • , .'-~ \~"J.."'I'';';' • , • r;.: ----~ ).J I J -., 

\

' j • , ...' ' .. 

L.. I • - .. ~ \ __ • I . ~.-.- - • J 

, " 1".:.--.'---. ---.-.. .-.,&.- .""-.;7 ~ ... r.r--,- ,-";: .. -1 ,/" A, ........ , 

• I. " J ..... --.-..~-). '. Allen 

• • L . -., . '~' " ,,- • I ~ I \ 

'.'-L~ ,- Ld:C:'7-~J\ •. ~ L \ ,i' Smith "- 1, 

'-! ". 

Figule 1. Location of waste disposal sites selected for evaluation. 

posed program of site development, 

physical and chemical sampling, and 

analysis and engineering/cost assessments, were developed. The test plans 

were reviewed by EPA and the utility 

involved, and their comments were incorporated. 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 agencies, site development was begun. Site 

development and physical testing were 

governed by procedure manuals developed for this project. The activities involved in site development included the 

drilling of borings; excavating test pits; 

collecting waste, soil, and water samples; conducting field permeability 

tests; installing ground water monitoring wells and piezometers; and documenting each activity. These activities 

took place at each of the six sites in time 

periods of 2 to 4 weeks. Table 4 indicates 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 performed; i.e., laboratory soil classification and permeability tests on waste 

samples from the sites. Preliminary 

4 

water balances were also developed for 

each site. 

Chemical Sampling and Analysis 

At each site, a program of chemical 

sampling and analysis was undertaken. 

This program included characterization 

of waste, water, and soil samples obtained from site development, and 

ground water well and (in some cases) 

surface water samples subsequently 

obtained from a series of visits scheduled to correspond to relatively wet, relatively dry, and intermediate periods for 

each site. Table 5 summarizes the sampling and analysis program. 

Chemical samples are subjected to 

several types of analyses: ion chromatography (lC) for six anions; inductively coupled argon plasma emissions 

spectroscopy (leAP) 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 capacity 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 Extractior 

Procedure (EP); results from these test~ 

are summarized in Table 6. Furthel 

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 effects evaluation throughout the project. The individual site evaluations 

were developed in five steps: (1) a review and evaluation was made of 

available background information on 

the disposal operation and its environmental setting; (2) present disposalrelated water quality effects were 

identified and described based on 

evaluation and measured information 

developed in this project; (3) apparent 

cause/effect relationships were hypothesized 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 implications of the findings at the individual 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 reported: 

1. Data suggest that no major adverse environmental effects have 

occurred at any of the sites. For example, data from wells downgradient 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 established by EPA. 

2. The results from the sites are internally consistent. In other words, 

the analyses of samples taken on 

different dates at the same locations 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 explain many of the environmental 

effects that can result from coal 

ash and FGD waste disposal. 
Table 4. Summary of Site Development/Physical Testing 

Number of 

Date Number of 

Laboratory Physical Tests 

Development Unified Soil 

Completed Test Soil Classification 

Plant (mo/yr) 80r;ngs Wells Pits Samples Series (USCS) Permeability 

Allen 07181 20 20 2 152 18 4 

Elrama 03/81 20 16 4 199 17 13 

Johnston 05/81 14 12 10 154 12 7 

Sherco 08/81 13 11 178 20 6 

Powerton 11/81 11 9 112 30 8 

Smith 12/81 25 24 146 15 8 

Table 5. Summary of Chemical Sampling and Analysis Program 

Analysesb 

Samplesa Trip 1 Trips 2, 3, and 4 

Site Trip 1 Trips 2, 3, and 4 ICAP IC As/Se Field Data Other 

Allene wells wells and X X X X 

ash solids surface waters X X 

interstitial liquors X X X 

soils X X 

Elrama wells wells, Iysimeters, X X X X 

waste solids surface waters X X Xd 

soil X X 

waste extracts X 

Sherco wells wells and X X X X 

waste interstitial surface liquors X X X 

liquors 

waste solids X 

liner solids X 

liner liquor X X 

soil solids X 

soil extracts X 

Smith liquids wells and X X X X 

waste solids surface waters X 

interstitial waste X X 

liquors 

soil X 

soU liquors X X 

Powerton wells wells and X X X X 

waste solids surface waters X 

Dave Johnston wells wells and X X X X 

waste solids surface waters X X 

waste extracts X 

soils X 

-Samples obtained during site development and subsequent sampling and analysis trips. 

bAnalyses performed are abbreviated as follows: 

ICAP-Ag. AI, B, Ba, Be. Ca, Cd, Co, Cr, Cu. Fe, K. Mg, Mn, Mo, Na, Ni. p, Pb, Si, Sr, Th, n, V. Zn. Zr. (Does not include B. Ba, and Si for solids.) 

IC-F-. CI-, NO[j, SO;. 8r-. POj-. 

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. 

dlncludes solids characterization for 501-, total oxidizable sulfur, slurry pH, acid insolubles. 

5 
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 background) concentrations of several 

waste-related chemical constituents (e.g., boron, sulfate, calcium, arsenic). However, the surrounding soils have attenuated 

significant fractions of leachate 

constituent contaminants within 

the immediate vicinity of the 

ponds. 

2. Leachate water from the upgradient 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 high concentrations 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 Iysimeter; 

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 constituents in downgradient ground 

water may be explained by the relatively short time the fill has been 

in operation (4 years). chemical! 

physical attenuation phenomena 

(including the effects of the treatment/disposal process), or a combination of these factors. 

4. The landfill does not appear to 

alter significantly the local concentrations of some constituents 

(such as sulfate) potentially available 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 peripheral 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 fOI 

both unsaturated and saturate( 

zone travel. 

2. Most of the "elevated" measure, 

ments reflect pervasively higt 

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 highl~ 

mineralized arid areas there ma,; 

be areas of good water quality tha1 

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 significant elevations of chemical constituents in the leachate at downgradient wells. 

2. A waste-related influence is reflected in the slightly elevated 

levels (of boron and sulfate) measured in the peripheral/downgradient wells to the west and southwest, 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 ofthe pervious soils in the 

area of the site, significant inTable 6. Summary of Results of Extraction Procedure (EP) Tests of 20 Fly Ash and 3 FGD Waste Grab Samples 

Overall Range Observed, fLgll Interim Primary Drinking Ratio of Range Observed to Standards 

Metal Fly Ash FGD Waste Water StandardsB, fLgll Fly Ash FGD Waste 

Arsenic <2 - 410 <2 - 65 50 <0.04 - 8.2 <0.04 - 1.30 

Barium <100 - 700 <150 - 230 1000 <0.1 - 0.7 <0.15 - 0.23 

Cadmium <2 - 193 <2- 20 10 <0.2 - 19.3 <0.2 - 2 

Chromium <8 - 930b <11 - 26b 50b <0.16 - 18.6 <0.22 - 0.52 

Lead <3 - <36 <5 50 <0.06 - 0.72 0.1 

Mercury <2 <2 <1 <1 <1 

Selenium <2 - 340 8- 49 10 <0.2 -34 0.8 - 4.9 

Silver <1 <1 50 <0.02 <0.02 

aThese standards are M ... 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 ",g/I (depending on temperature), and for nitrate (as N): 10,000 ",g/I. 

bAn amendent to the chromium criteria for the EP revises it from total chromium to Cr(VI); since the total chromium values were measured by atomic absorption 

(AA), the measured ranges represent upper limits for Cr(V1) in the samples. 

6 
creases in concentrations of major 

soluble species are expected to occur in downgradient wells in the 

next few years. Secondary drinking water standards are expected 

to be exceeded in these wells. 

However, any effects of movement 

of these species off-site will be mitigated (diluted) by the Mississippi 

River, which flows by the plant. 

4. The higher concentrations of 

waste parameters in FGC pond supernatant versus underlying waste 

interstitial waters may be due to 

two factors: (1) the conversion by 

the utility to a system involving recycle of the FGC waste transport 

water would have resulted in increased concentrations of chemicals in the water; and (2) the evaporation of water in the pond would 

also increase remaining chemical 

concentrations. 

Powerton-The results indicate: 

1. Although the completed landfiff 

was supposed to have a 0.25 m 

(8 in.) Poz-O-Tec liner, during the 

coring operation a general absence of liner material was observed. This observation is consistent with the practical difficulty of 

achieving uniform placement of 

such a relatively thin layer of soillike material over a large area. Current engineering practice suggests 

that a minimum thickness of 0.45 

to 0.60 m (18 to 24 in.) of liner 

placement would be desired to ensure full effectiveness. 

2. The surface water analytical results for lost Creek are consistent 

with the water balance calculations. Both sets of results indicate 

that the stream has adequate assimilative/dilution capacity to 

lower current concentrations of 

chemical constituents in leachate 

reaching lost Creek to insignificant levels. 

3. The results also suggest that the 

stream, if an effective ground 

water flow divide, may limit the extent 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 dilution is preventing the release of 

significant quantities of these elements and/or elevation to significant concentrations at downgradient 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 expected due to admixing of leachate 

with the greater amounts of dilution water. 

3. The use of high total dissolved 

solids Bay water in the pond for 

makeup and its presence in adjacent downgradient areas create a 

situation where little incremental 

effect is detectable from such typical ash pond "tracer" species as 

sulfates, chlorides, and boron. 

Generic Environmental Evaluation 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 effectively evaluated using a matrix consisting of four waste types, three disposal 

methods, and five environmental settings. 

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 flyash/bottom-ash/FGD-waste mixtures (excluding chemically 

treated FGD wastes; see item 3, 

below). 

2. Non fly ash materials. This category includes bottom ash (or 

boiler slag) and FGD wastes that 

are disposed of separately from fly 

ash (including forced oxidation 

wastes). This category usually contains lesser concentrations oftrace 

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 stabilized for full-scale disposal by a variety 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 disposal is presently practiced at 

some power plants and is expected to grow in importance. Processed FGD wastes are a separate 

category because of the differences in their physical and chemical properties created by the stabilization process. 

4. Dry FGD wastes. Several dry FGD 

systems are expected to come into 

commercial use over the next 

3 years. It appears that calciumbased dry FGD systems are anticipated to grow more than sodiumbased systems. By either process, 

dry FGD systems provide a combined waste (containing fly ash 

and the sulfur compound) in a relatively dry form that is likely to be 

sent for disposal to a managed 

landfill. The physical and chemical 

properties of these wastes are expected to be different from the 

other categories discussed above; 

additionally, there is a relative lack 

of even limited field scale information on their leaching characteristics to date. 

Three disposal methods for coal ash 

and FGD wastes are in practice and expected to continue in the future: 

(1) pond disposal; (2) interim ponding 

followed by landfill disposal; and 

(3) landfill disposal (including disposal 

in mines, which is considered a special 

case of landfilling). 

Three of the five environmental settings for solid waste disposal are based 

on major differences in climate and hydrogeology: (1) coastal areas, specifically where surface water and ground 

water are influenced by the ebb and 

flow of tides; (2) arid areas, characteristic of much of the western U.S., where 

net evaporation generally exceeds pre7 
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 balance between precipitation and evaporation and where permanent surface 

water bodies are in such abundance as 

to be near many disposal sites. 

Further evaluations during this project suggested that a further breakdown 

of two special categories would be useful because of their singificant characteristics: (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 setting tend to have water quality characteristics that can potentially show less 

of an incremental effect from coal ash 

and FGD waste leachates. This is because 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 environmental settings and indicates combinations 

for which field-scale and other information is available. Sources of data and 

information other than this study included the Utilities Solid Waste Activities Group (USWAG), the Electric Power 

Research Institute (EPR!), and the Department of Energy (DOE). DOE is currently 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 practiced in the future. 

It appears that, on balance, technology exists for environmentally sound 

disposal of coal ash and FGD wastes 

using any of the modes of disposal. Potential environmental effects are highly 

site and system specific. For some combinations 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 effects of waste disposal. 

Engineering/Cost Evaluations 

The first major efforts in the engineering/cost evaluations involved development of site-specific conceptual engineering designs and costs (capital and 

first year operating and maintenance 

costs) for the current solid waste handling 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 

Fly 

Ash8 

Non-Fly Processed Dry Fly 

Ash a 

Non-Fly Processed Dry 

Setting Ashb FGD FGD Ashb FGD FGD 

Coastal X 

SmithC 

P NA NA XlPd 

Chisman 

Cr. 

(USWAG) 

P P NA 

Arid WesternNot Highly Mineralized 

Arid WesternHighly Mineralized 

InteriorNot Highly Acidic 

InteriorHighly Acidic 

(mine drainage) 

P 

P 

x 

Allen, 

Sherco, 

Michigan City 

(USWAG), 

Wallingford 

(USWAG) 

P 

P 

P 

P 

P 

NA 

NA 

X 

Bruce 

Mansfield 

P 

Notes: a. Includes co-disposal of fly ash with other wastes. 

NA 

NA 

NA 

NA 

b. Includes FGD wastes without fly ash and bottom ash. 

P 

P 

Xlpd 

Bailly 

(USWAG) 

P 

P P 

P P 

P P 

P P 

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 

NA 

NA 

NA 

NA 

Fly 

Ashb 

P 

P 

x 

Dave 

Johnston; 

Milton 

Young 

(DOE/EPA) 

X 

Powerton, 

Zuellinger 

(USWAG) 

Hunts 

Brook 

(USWAG) 

Dunkirk 

(DOE) 

P 

Landfilling 

Non-Fly 

Ashb 

P 

P 

P 

P 

P 

Processed 

FGD 

P 

P 

P 

X 

Conesville 

(EPRI/USWAG) 

X 

Elrama 

Dry 

FGD 

pe 

pe 

pe 

pe 

pd 
of the cost data, the estimates were de- ing waste handling and disposal for coal 

veloped by breaking down the waste ash and FGD wastes. Tables 8 and 9 

handling and disposal operations into summarize results of this effort. 

five modules: (') raw material handling The range of costs given represents 

and storage; (2) waste processing and variations in specific plant operations as 

handling; (3) waste storage; (4) waste well as variations in the several cost estransport; and (5) waste placement and timates used in preparing these estidisposal (including site monitoring and mates. For example, the higher end of 

reclamation). the range for FGD waste handling/proBased on the site-specific cost esti- cessing might include thickening, vacmates and other studies by TVA, EPRI, uum filtration, and mixing with lime and 

and other organizations, generic capital fly ash, while the lower end could repreand O&M cost estimates were then pre- sent a simpler operation with little or no 

pared for individual modules compris- processing. Figures 2 and 3 show the 

Table 8. Generic Capital Cost Estimates for FGC Waste Disposal (Late 1982 Dol/ars}8 

Module SUbmodule 

Fly ash handling/processing Wet handling wlo recycle 

Wet handling wlrecycle 

Dry handling 

Fly ash storage Dry 

Fly ash transport Wet sluicing 

Dry trucking 

Fly ash placement/disposal Unlined pond 

Landfill 

Bottom ash handlinglprocessing Wet handling wlo recycle 

Wet handling w/recycle 

Bottom ash transport Wet sluicing 

Dry trucking 

Bottom ash placement/disposal Unlined pond 

Landfill 

Raw material handling/storage Dry llime and fly ash) 

FGD waste handling/processing C Wet handling 

FGD waste transport Wet sluicing 

Dry trucking 

FGD waste placement/disposal Unlined pond 

Landfill 

"Engineering News Record (ENR) Index = 3931.11 (1913 - 100) 

b = 365.97 (1967 - 100) 

Relationship between plant size and waste generation for typical case: 

250b 

2.3-4.3 

3.7-6.8 

2.2-4.1 

4.7-8.8 

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 

Annual Waste Generation Rate 

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 disposal of coal ash and FGD wastes from 

coal-fired electric generating plants provide major technical guidance for regulatory bodies and the utility industry. 

However, results from field studies of 

this type are limited, and predictive 

Capital Cost Range 

($/kW) 

Plant Size (MW) 

500b 1000b 2000b 

1.9-3.5 1.5-2.9 1.3-2.3 

3.0-5.5 2.4-6.4 1.9-3.6 

1.8-3.3 1.4-2.7 1.2-2.2 

4.2-7.7 3.7-6.8 3.2-5.9 

2.7-5.1 2.2-4.0 1.7-3.2 

0.3-0.6 0.3-0.5 0.2-0.5 

12.9-23.9 11.0-20.5 9.4-17.5 

3.3-6.1 2.5-4.7 1.9-3.6 

1.7-3.2 1.3-2.5 1.0-1.9 

2.0-3.7 1.6-3.0 1.3-2.4 

2.4-4.5 1.9-3.6 1.5-2.8 

0.2-0.3 0.1-0.2 0.1-0.2 

5.1-9.6 4.2-7.7 3.4-6.2 

1.1-2.0 0.9-1.6 0.7-1.3 

2.1-3.9 1.9-3.4 1.6-3.0 

15.2-28.3 12.8-23.8 10.8-20.0 

0.5-7.0 0.4-0.8 0.4-0.7 

0.3-0.6 0.3-0.5 0.3-0.5 

8.9-16.6 7.9-74.7 7.0-13.1 

3.3-6.2 2.7-5.0 2.2-4.0 

(dry metric tonslMW of Plant Generating Capacity) 

Fly Ash 

Bottom Ash 

FGD Waste 

NTypical Case" Assumptions 

Coal Properties: 

Load Factor: 

Heat Rate: 

S02 Removal: 

Lime Stoichiometry: 

Fly AshlBottom Ash Ratio: 

cAssumed FGD System: Wet Lime Scrubbing 

280 

70 

240 

2% 5, 13% Ash, 10,500 Btullb (24.4 x 106 MJlkg) 

70% 

10,250 BtulkWh (10.8 x 106 MJlkWh) 

90% 

1.1 

80120 

9 
tools (e.g., computer models) for evaluating 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 develop more sophisticated tools for predicting and analyzing the potential environmental effects of coal ash and FGD 

waste disposal. 

Table 9. Generic Annual Cost Estimates for FGC Waste Disposal (Late 1982 Dollars)8 

Module Submodule 

Fly ash handling/processing Wet handling w/o recycle 

Wet handling w/recyc/e 

Dry handling 

Fly ash storage Dry 

Fly ash transport Wet sluicing 

Dry trucking 

Fly ash placement/disposal Unlined pond 

Landfill 

Bottom ash handling/processing Wet handling w/o recycle 

Wet handling w/recycle 

Bottom ash transport Wet sluicing 

Dry trucking 

Bottom ash placement/disposal Unlined pond 

Landfill 

Raw material handling/storage Dry (lime and fly ash) 

FGD waste handling/processing C Wet handling 

FGD waste transport Wet sluicing 

Dry trucking 

FGD waste placement/disposal Unlined pond 

Landfill 

8Engineering News Record (ENR) Index = 3931.11 (1913 - 100) 

= 365.97 (1967 - 100) 

bRelationship between plant size and waste generation for typical case: 

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 

9.2-77.7 

5.4-70.0 

4.1-7.6 

17.2-31.9 

1.1-2.1 

2.9-5.4 

8.5-15.8 

4.0-7.5 

Annual Waste Generation Rate 

Annual Cost Range 

($Idry metric ton) 

Plant Size (MW) 

500b 1000b 

1.0-3.7 1.6-3.0 

2.9-5.4 2.3-4.3 

2.1-3.9 1.7-3.2 

3.0-5.6 2.8-5.2 

3.2-5.9 2.5-4.7 

1.5-2.8 1.3-2.5 

9.1-16.8 7.2-73.5 

5.6-10.5 4.6-8.5 

9.0-16.7 6.9-72.8 

10.3-19.1 8.4-15.7 

7.3-13.5 5.6-10.3 

2.8-5.2 2.2-4.1 

7.9-14.6 6.5-72.7 

4.7-8.8 4.1-7.6 

3.7-6.7 3.4-6.2 

13.8-25.5 11.0-20.5 

0.9-1.7 0.7-1.3 

2.3-4.3 1.8-3.3 

6.7-12.4 5.2-9.7 

3.4-6.3 2.8-5.3 

(dry metric tonslMW of Plant Generating Capacity) 

Fly Ash 

Bottom Ash 

FGD Waste 

NTypical Case N Assumptions 

Coal Properties: 

Load Factor: 

Heat Rate: 

S02 Removal: 

Lime Stoichiometry; 

Fly Ash/Bottom Ash Ratio: 

cAssumed FGD System: Wet Lime Scrubbing 

10 

280 

70 

240 

2% S, 13% Ash, 10,500 Btu/lb 124.4 x 106 MJ/kg) 

70% 

10,250 Btu/kWh (10.8 x 106 MJ/kWh) 

90% 

1.1 

80/20 

2000b 

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 

5.4-70.0 

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 
Metric tons/year 

100.000 200.000 300.000 400.000 5QOOOr---------~----------~--------~--------~~--_, 

45.000 

-.:::-

~ 40.000 

~ 35.000 .... 

c 

~ 30.000 C1l 

III 

~ 25.000 

~ 'OJ 20.000 c 

<..l 

<ii 15.000 'i 

<..l 10.000 

-!!! 

.!: 5.000 I 

Basis: 1982 Dol/ars 

o ~ ________ ~ __________________ ~ ________ ~ ________ ~ 

o 

Figure 2. 

8.000 

-.:::-

C1l 

CIl 

:.. 

" <I) 6.000 .... 

c 

~ c: 

C1l 

III 

:;, 

C 

~ 4.000 ... 

III 

C 

<..l 

1::1) 

'S C1l 

... 2.000 CIl 

Cl. 

0 

<ii 

:;, 

c: 

c: 

oq:: 

0 

0 

Figure 3. 

100.000 200.000 300.000 400.000 500.000 

FGD Waste Generation Rate (tons/year) 

FGD waste handling and processing: capital costs versus FGD waste generation 

rate. 

Metric tons/year 

100.000 200.000 300.000 400.000 

Basis: 1982 Dol/ars 

100.000 200.000 300.000 400.000 500.000 

FGD Waste Generation Rate (tons/year) 

FGD waste handling and processing: annualized costs versus FGD waste generation 

rate. 

11 

trU. S. GOVERNMENT PRINTING OFFICE: 1985/559-111/20670 
C. Santhanam, A. Balasco, I. Bodek. and C. 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 0471 AS; Cost 

$157.00, subject to change), consists of six volumes: 

"Volume I. Sections 1 through 5," (Order No. PB 85-228 0541 AS; Cost 

$29.50, subject to change). 

"Volume II. Sections 6 Through 9," (Order No. PB 85-228 0621 AS; Cost 

$22.00, subject to change). 

"Volume III. Appendices A and B," (Order No. PB 85-228 0701 AS; Cost 

$34.00, subject to change). 

"Volume IV. Appendices C Through E," (Order No. PB 85-228 0881 AS; Cost 

$40.00, subject to change). 

Volume V. Appendix F," (Order No. PB 85-228 0961AS; Cost $41.50, 

subject to change). 

Volume VI. Appendices G Through I," (Order No. PB 85-228 1041 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. Environmental Protection Agency 

Research Triangle Park. NC 27711 

United States 

Environmental Protection 

Agency 

Official Business 

Penalty for Private Use $300 

E P Al600/57 -85/028 

Center for Environmental Research 

Information 

Cincinnati OH 45268 

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