# &

# 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 electricgenerating plants.Thestudy involved characterization ofwastes, environmental data gathering, evaluation ofenvironmental effects, and engineering/cost evaluations of disposal practicesatsixsitesaroundthecountry. Results of the study provide technical background data and information to EPA, stateand local permittingofficials, and the 

### utility industryfor implementing environmentally sound disposal practices.

Data from the study suggest that no major environmental effects have occurred at any ofthe six sites; i.e., data from wells downgradient of the disposal sites indicatethatwaste leachate has resulted in concentrationsofchemicals lessthanthe EPA primarydrinking 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)-showsthat, on balance, technology exis,s for environmentally sound disposalofcoal ash and FGD wastesfor 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 mostpotentiallyadverse effects of coalash and FGD wastedisposal. Costs ofwastedisposal operationsare highly system and site specific. This Project Summary was developedbyEPA'sAirandEnergyEngineering Research Laboratory, Research Triangle Park, 

### Ne, to announce key findings ofthe 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/costevaluations ofdisposal 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 reportto 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 generatetwo majorcategories ofwaste 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 "highvolumewastes." Numerousother wastes, generated in smallerquantities, 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 utilityboilers is collected by mechanical collectors 

### andl or electrostatic precipitators, fabric filters, orwet 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 productsulfurorsulfuricacid). 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 ofthe coal ash and all ofthe 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 manyyears. Utilization of FGC waste is expected to grow but at a slower rate than FGC waste generation. A significant fraction ofthe 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
CoalAsha Projections ofFGC 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 continueto 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 maybe afuture alternative if it can be practiced under environmentally and economically acceptable conditions. The principal methods ofdisposal on land are: ponding, landfilling (including disposal in surface mines), and interim pondingfollowed by landfilling. Table 2 presents data on current practices based on data obtained on 176 plants.

Ponding of FGC waste is morewidely practiced than any other disposal method. Ponding can be employedfora widevarietyofcoal 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 usuallyexpensive. In thefuture, 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 aspecial 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 gypsumwould be dredged and stacked around the perimeter ofthe pond, thus building up the embankments.

Landfilling of FGC waste is also widely practiced, and can involveone or moreofavarietyofhandlingoperations 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 mustalso be appliedtofly ash that is sluiced from the plant or is wetscrubbed from the flue gas-with or without significant quantities of SO, Wet FGD waste mustalso be dewatere( via thickening, vacuum filtration, and, i necessary, blending with dryfly 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 ofthese**system~** on utility boilers was just beginning.

In a landfill disposal site, the wastef are spread on the ground in 0.3to 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 ofthe site. The ul· timate height of a disposal fill is site specific, butcan 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 disposalis avariation oflandfilling 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 isconsiderably less than the amount of coal burned, many mineswould havethecapacityfordisposalthroughoutthe lifeof 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 thefuture, particularlysince dry ash handling and disposal is being more widely practiced. 

## Site Selection and Test Plan Preparation Candidate Site Selection Pro

## cess

The overall objective ofthe 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 oftwo 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 targetof25 to30 sites, including 18 candidate and 7to 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, butwere notabsolutely limited by that number. The attemptwas 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

Table2. CurrentFGC Waste Disposal Methods Utilizedat UtilityCoal-FiredPowerPlants in the U.S. (Data Base: 

### 176 Plants a: 

### 200 MW)S 

### The candidate and backup sites were then subjectedto a moredetailed evaluation. These evaluations included one or more detailed sitevisits by engineering, environmental, and hydrogeologic specialists assignedtothe project. Their findings,togetherwith mid-course evaluations that were continuously taking place, supported an iterative process that resulted in the selection ofthefinal 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 Flyash 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 ofPlants
LandfillC
46 13 9

7

6 1 Interim PondlLandfillc

6 

### 29 16

aCoal-firedplants on which data were available (;;;:;80% oftheirpowergenerated from coal in 1977) which have generating capacities ;;;:;200 MWwith the exception offourplants employing FGO systems. Figures representthe numberof plantsat which each waste type/disposalmethodispracticed. (Note: Manyplants utilize more than one method.) 

### Test Plan Preparation

blncludes directpondingandinterimlfinalponding methods. clncludes managedand unmanaged fills andmine 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 (GulfPower) (Bay) aUL 

### =Unlined. CL 

### =Clay-Lined. AL = ArtificiallyLinedfPoz-O-Tec}. 

### Detailed test plans providing background information on each ofthesites, 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 andbottom ash (UL; offsite) Flyash 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

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Figule 1. Location ofwaste disposalsites selectedfor 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

Afterapprovalsfromthe utilityand, in somecases, from state regulatoryagencies, site development was begun. Site development and physical testing were governed by procedure manuals developed for this project. The activities involved in site development includedthe 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 ofthe 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 correspondto relativelywet, relativelydry,and intermediate periodsfor 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 ofthis project,23 grabsamples of wastes from 18 plants were obtained and analyzed using the EPA Extractior Procedure (EP); resultsfrom 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 ofthe 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 thedisposal operationand itsenvironmental setting; (2) present disposalrelated water quality effects were identified and described based on evaluation and measured information developed inthis project; (3) apparent cause/effect relationships were hypothesized to explain the findings at the sites; (4) potentialfuture 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 genericassessment,discussed laterin 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 ofthe sites. For example, datafromwellsdowngradient 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 resultsfrom 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 ofSite Development/Physical Testing Numberof
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 ofChemical Sampling andAnalysis 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 linersolids 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 obtainedduring site developmentandsubsequentsampling andanalysis trips. bAnalysesperformed are abbreviatedas 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, andSi forsolids.)

IC-F-. CI-, NO[j, SO;. 8r-. POj-. As/Se-eitherorboth on selectedsamples. Field Data-ground waterlevel, pH. dissolved oxygen, conductivity, temperature. cOthersamples were obtained (boilercleaning wastes). Analysis was limited to ICAP, pH, andbromate. dlncludes solids characterization for501-, total oxidizable sulfur, slurrypH, acid insolubles.
5A brief account ofthe results at each ofthe 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 ofthe 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 ofthe sitewas 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 norcalcium 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, itdoes notappearto 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 bythe 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 ofthese factors. 4. The landfill does not appear to alter significantlythe 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-yearold inactive landfillto a much closer (to the landfill) down gradientwell 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 highlymineralized groundwater 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 ofgoodwaterqualitytha1 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 bythe clay linerto 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 (ofboron and sulfate) measured in the peripheral/downgradientwellstothewestand southwest, but it is not clear whether this is due to past leakage from the sheet piling/conduit area, to leachatethat has moved through the liner, or to a combination of these two sources. 3. Because ofthe pervioussoils inthe area of the site, significant inTable 6. Summary ofResults ofExtraction Procedure (EP) Tests of20 FlyAsh and3 FGD Waste Grab Samples

Overall Range Observed, fLgll Interim Primary Drinking Ratio ofRange Observedto Standards Metal FlyAsh FGD Waste Water StandardsB

, fLgll FlyAsh 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 whethersolidwaste disposal activities comply with ground watercriteria

.• Standards included, butnotmeasured in these tests, are for fluoride: 1400-2400 ",g/I (depending on temperature), and for nitrate (as N): 10,000 ",g/I. bAn amendentto the chromium criteria for the EP revises it from total chromium to Cr(VI); since the total chromium values were measured byatomic absorption

(AA), the measured ranges represent upper limits for Cr(V1) in the samples.
6

### creases in concentrations of major soluble species are expectedtooccur in downgradient wells in the next few years. Secondary drinking water standards are expected to be exceeded in these wells. However, any effects ofmovement ofthese species off-sitewill be mitigated (diluted) by the Mississippi River, which flows by the plant. 4. The higher concentrations of waste parameters in FGC pond supernatantversus underlying waste interstitial waters may be due to two factors: (1) the conversion by the utilityto asystem involving recycle of the FGC waste transport water would have resulted in increased concentrations of chemicals in the water; and (2) the evaporation ofwater 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 overa largearea. Current engineering practice suggests that a minimum thickness of 0.45 to 0.60 m (18 to 24 in.) of liner placementwould be desiredto 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 waterflowdivide, maylimittheextent of further downgradient ground water contamination by the waste plume. 4. The general lack of elevated trace metal concentrations in ground watersuggeststhat acombination ofchemical 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 inthe pond and in the immediately adjacent downgradient areas. 2. There appears to be little or no chemical attenuation of the major tracerspecies such as calcium and strontium, but rathera progressive reduction in concentrations in the downgradient direction. This is consistent with whatwould be expected duetoadmixing ofleachate 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 ofcoal 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 ofseparatelyfrom fly ash (including forced oxidation wastes). Thiscategory usuallycontains 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 orstabilized forfull-scale disposal byavariety of processes; the processes presently in commercial practice involvethe addition oflimeandfly ash, or processed slag. lime/fly ash stabilization for landfill disposal is presently practiced at some power plants and is expectedto growin importance. Processed FGD wastes are a separate category because of the differences in their physical and chemical properties created bythe stabilization process. 4. Dry FGD wastes. Several dry FGD systems are expectedto come into commercial use over the next 3years. 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 andthesulfurcompound) ina relatively dry form that is likely to be sent for disposal to a managed landfill. The physical and chemical properties ofthese wastes are expected to be different from the other categories discussed above; additionally,there is a relative lack ofeven limitedfield 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 oftides; (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 ofthe 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 oftwo special categories would be useful because of their singificant characteristics: (1) arid areas inthewestwhere 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 numberofchemicals found in the leachate.

Table 7 is a matrix of waste types, methods of disposal, and environmental settings and indicates combinations forwhich 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 ofdisposal of FGD wastes in asurface mine; thestudy was originally sponsored by EPA. As is clear, some information is available for mostofthe combinationsthat 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 ofthe modes ofdisposal. 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 specificapplication ofgoodengineering design and practice can mitigate most potentially adverse environmental effects ofwaste disposal. 

### Engineering/Cost Evaluations

The first majorefforts inthe 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 studysites. Tofacilitatethe ultimate use

Table 7. Summary ofInformation Available for Combinations ofWaste Types, Disposal Methods, andEnvironmental Settings Ponding Interim Ponding/Landfilling Fly Ash8 Non-Fly Processed Dry Fly Asha 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 HighlyMineralized

Arid WesternHighlyMineralized

InteriorNot HighlyAcidic

InteriorHighlyAcidic (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 offly ash with other wastes. NA

NA

NA

NA

b. Includes FGD wastes without fly ash andbottom ash. P

P

Xlpd Bailly (USWAG)

P P P

P P

P P

P P

c. Plants for which data and information are obtainedare listed in theirappropriate positions. d. Either the interim pondor landfill aspect ofoperation studiedat field scale, butnotboth. e. Laboratory data only. Key: 

### x = Data available from full-scale field studies. P = Data available from laboratoryand/orlimited-scale field studies forprojection purposes. NA = Matrix combination notapplicable due to lack ofpresentand 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

### ofthe cost data, the estimates were de- ingwaste handlingand disposalforcoal veloped by breaking down the waste ash and FGD wastes. Tables 8 and 9 handling and disposal operations into summarize results ofthis effort. five modules: (') raw material handling The range of costs given represents and storage; (2) waste processing and variations inspecific plantoperationsas 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, uumfiltration,and mixingwith limeand and other organizations, generic capital flyash, whilethe lowerendcould repreand O&M cost estimates werethen pre- sent asimpleroperation 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 Flyash storage Dry Flyash transport Wetsluicing Dry trucking Fly ash placement/disposal Unlinedpond Landfill
Bottom ash handlinglprocessing Wet handling wlo recycle Wet handling w/recycle

Bottom ash transport Wet sluicing Dry trucking
Bottom ash placement/disposal Unlinedpond Landfill
Rawmaterial handling/storage Dry llime and fly ash)
FGD waste handling/processingC Wet handling
FGD waste transport Wet sluicing Dry trucking
FGD waste placement/disposal Unlinedpond Landfill "Engineering News Record (ENR) Index

### =3931.11 (1913

- 100) b = 365.97 (1967

- 100) Relationship between plantsize 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 allthe modules listed inTables 8and 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 electricgenerating plants provide majortechnical 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 tonslMWof Plant Generating Capacity) FlyAsh Bottom Ash FGD Waste NTypical Case"Assumptions Coal Properties: Load Factor: Heat Rate: S02 Removal: Lime Stoichiometry: FlyAshlBottom 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 betweenthesewastes and site-specific hydrogeologicsystems are, in many cases, inadequate. Forthis 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 Flyash handling/processing Wet handling w/o recycle Wet handling w/recyc/e Dryhandling Fly ash storage Dry Flyash transport Wet sluicing Dry trucking Flyash placement/disposal Unlinedpond 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 Unlinedpond Landfill

Rawmaterial handling/storage Dry (lime and fly ash)
FGD waste handling/processingC Wet handling
FGD waste transport Wet sluicing Dry trucking
FGD waste placement/disposal Unlinedpond Landfill 8Engineering News Record (ENR) Index = 3931.11 (1913

- 100)

= 365.97 (1967

- 100) bRelationship between plantsize 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 tonslMWofPlant Generating Capacity)
FlyAsh Bottom Ash FGD Waste NTypical Case N Assumptions Coal Properties: Load Factor: Heat Rate: S02 Removal: Lime Stoichiometry; FlyAsh/BottomAsh 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 2.4-4.4Metric 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 andprocessing: 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 wastehandlingand processing:annualizedcosts versusFGD wastegeneration rate.

11

trU. S. GOVERNMENT PRINTINGOFFICE: 1985/559-111/20670

### C. Santhanam, A. Balasco, I. Bodek. and

### C. Cooperare withArthurD. Little, Inc., Cambridge, MA 02140;J. Humphreyis withHaleyandAldrich 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 FieldEvaluation ofWaste Disposalfrom

Coal-firedElectric GeneratingPlants"(Set OrderNo. PB85-2280471 AS; Cost $157.00, subject to change), consists ofsix 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,"(OrderNo. PB85-228 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,"(OrderNo. PB 85-228 1041 AS; Cost $17.50, subject to change). The above reports willbe available only from: National TechnicalInformation Service 5285 PortRoyalRoad Springfield. VA 22161 Telephone: 703-487-4650 The EPA Project Officercan be contactedat: AirandEnergyEngineering Research Laboratory U.S. EnvironmentalProtectionAgency Research Triangle Park. NC27711

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 BULK RATE POSTAGE & FEES PA EPA PERMIT No. G-36