B

C

Front cover: A. Eroded Lower Kittanning (No. 5) coal and underclay at the Fleming abandoned mine site before reclamation.

B. Graded spoil and topsoil at the Fleming abandoned mine site during reclamation. PFBC by-product and compost are in piles in background.

C. Fleming abandoned mine site three years after reclamation (1997). Small buildings on upper left of photo are shelter houses where water-quality samples were

collected from the six test watersheds.

Back cover: American Electric's Tidd Plant in Brilliant, Ohio, with the Ohio River in the foreground. (Photo courtesy of American Electric Power, Columbus, Ohio.

Reproduced with permission.)

A
Water Quality and Geochemical Modeling of 

Water at an Abandoned Coal Mine Reclaimed 

With Coal Combustion By-Products

By Ralph J. Haefner

U.S. Geological Survey Water-Resources Investigations Report 02-4216

Prepared in cooperation with

West Virginia University,

The Ohio Department of Natural Resources, Division of Mineral Resources Management, and

The Ohio Minelands Partnership
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Any use of trade, product, or firm names is for 

descriptive purposes only and does not imply

endorsement by the U.S. Government.

For additional information write to:

District Chief

U.S. Geological Survey

6480 Doubletree Avenue

Columbus, OH 43229-1111

Copies of this report can be purchased from:

USGS Information Services

Box 25286

Denver, CO 80225

Columbus, Ohio

 2002 
Contents III

CONTENTS

Abstract.................................................................................................................................................................................. 1

Introduction ........................................................................................................................................................................... 2

Purpose and scope........................................................................................................................................................ 2

Acknowledgments........................................................................................................................................................ 2

Previous investigations.......................................................................................................................................................... 2

Study methods ....................................................................................................................................................................... 4

Hydrogeologic setting............................................................................................................................................................ 6

Water quality ......................................................................................................................................................................... 12

Chemical tracers of PFBC by-product......................................................................................................................... 17

Comparisons of water-quality data to established drinking-water standards ............................................................. 19

Geochemical modeling .......................................................................................................................................................... 21

Summary and conclusions ..................................................................................................................................................... 26

References cited..................................................................................................................................................................... 26

ILLUSTRATIONS

1. Map showing lysimeters, monitoring wells, and spring sites at the Fleming abandoned mine site,

Tuscarawas County, Ohio ....................................................................................................................................... 7

2. Diagrammatic hydrogeologic section along A-A′ showing shallow and deep aquifer at the

Fleming abandoned mine site.................................................................................................................................. 8

3. Map of potentiometric surface in the shallow aquifer on June 25, 2001,

at the Fleming abandoned mine site........................................................................................................................ 9

4. Hydrograph showing water levels and precipitation from cluster 4, Fleming abandoned mine site......................... 10

 5. Graph showing tritium concentration as a function of depth for ground-water samples collected

in 1995 at the Fleming abandoned mine site........................................................................................................... 11

6. Standard and modified piper trilinear diagrams of selected water samples from the

Fleming abandoned mine site.................................................................................................................................. 13

7-8. Bar graphs showing:

7. Median pH, specific conductance, boron, magnesium-to-calcium mole ratios, sulfate, and

sulfur-isotope ratios for interstitial waters for each sampling round from the

Fleming abandoned mine site........................................................................................................................ 16

8. Median pH, specific conductance, boron, magnesium-to-calcium mole ratios, sulfate, and

sulfur-isotope ratios for ground and spring waters for each sampling round from the

Fleming abandoned mine site........................................................................................................................ 17

9-10. Scatterplots showing:

9. Relation of sulfate concentration to magnesium-to-calcium mole ratios for selected water samples

from the Fleming abandoned mine site ......................................................................................................... 18

10. Relation of the inverse of sulfate concentration to sulfur-isotope ratios for selected water samples

from the Fleming abandoned mine site ......................................................................................................... 19

11. Graph showing relation of pE to saturation index calculated for selected minerals from an application-area

interstitial-water sample collected at the Fleming abandoned mine site................................................................. 22

12-13. Boxplots showing:

12. Distribution of saturation indices for gibbsite, ferrihydrite, jarosite, and melanterite

for selected water samples from the Fleming abandoned mine site .............................................................. 24

13. Distr ibution of saturation indices for calcite, dolomite, ettringite, and gypsum for selected water

samples from the Fleming abandoned mine site ........................................................................................... 25
IV Contents

TABLES

 1. Solid-phase composition of PFBC by-product and maximum concentrations of constituents in mine

spoil and aquifer materials from the Fleming abandoned mine site, Tuscarawas County, Ohio ........................... 4

2. Rainfall amounts for the Northeast Hills, Ohio, 1993 through 2001 ........................................................................ 8

3. Discharge measurements at three spring sites at the Fleming abandoned mine site................................................. 11

4. Median values of water-quality characteristics from selected water samples collected at the

Fleming abandoned mine site ................................................................................................................................. 14

5. Comparison of Maximum Contaminant Levels for drinking water established by the

U.S. Environmental Protection Agency with analyses of all water samples obtained

from the Fleming abandoned mine site .................................................................................................................. 20

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

Temperature is given in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by use of the following 

equation: °F = 1.8(°C) + 32

Vertical datum: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a 

geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.

Abbreviated water-quality units used in this report: Chemical concentrations and water temperature are given in metric 

units. Chemical concentration is given in milligrams per liter (mg/L) or micrograms per liter (μg/L). Milligrams per liter is 

a unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume 

(liter) of water. One thousand micrograms per liter is equivalent to one milligram per liter. For concentrations less than 

7,000 mg/L, the numerical value is approximately the same as for concentrations in parts per million.

Specific conductance of water is expressed in microsiemens per centimeter at 25 degrees Celsius (μS/cm). This unit is 

equivalent to micromhos per centimeter at 25 degrees Celsius (μmho/cm), formerly used by the U.S. Geological Survey.

Stable isotope ratios, as referenced to the Canyon Diablo Troilite, are indicated by use of the delta symbol (δ) and are 

expressed in parts per thousand (per mil).

Tritium concentration is expressed in tritium units (TU). One tritium unit is equal to one tritium atom per 1018 hydrogen 

atoms; in terms of radioactivity, it is equivalent to 3.24 picocuries per liter. 

Multiply By To obtain

inch (in. 25.4 millimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

square foot (ft2) 0.09290 square meter

square mile (mi2) 2.590 square kilometer

acre 0.4047 square hectometer

cubic foot per second (ft3/s) 0.02832 cubic meter per second

ton 0.9072 megagram
ABSTRACT 1

Water Quality and Geochemical Modeling of Water at an 

Abandoned Coal Mine Reclaimed With Coal Combustion

By-Products

by Ralph J. Haefner

ABSTRACT

An abandoned coal mine in eastern Ohio was 

reclaimed with 125 tons per acre of pressurized fluidized bed combustion (PFBC) by-product. Water quality at the site (known as the Fleming site) was 

monitored for 7 years after reclamation; samples 

included water from soil-suction lysimeters (interstitial water), wells, and spring sites established downgradient of the application area. This report presents a 

summary of data collected at the Fleming site during 

the period September 1994 through June 2001. Additionally, results of geochemical modeling are included 

in this report to evaluate the potential fate of elements 

derived from the PFBC by-product.

Chemical analyses of samples of interstitial 

waters within the PFBC by-product application area 

indicated elevated levels of pH and specific conductance and elevated concentrations of boron, calcium, 

chloride, fluoride, magnesium, potassium, strontium, 

and sulfate compared to water samples collected in a 

control area where traditional reclamation methods 

were used. Magnesium-to-calcium (Mg:Ca) mole 

ratios and sulfur-isotope ratios were used to trace the 

PFBC by-product leachate and showed that little, if 

any, leachate reached ground water. Concentrations of 

most constituents in interstitial waters in the application-area decreased during the seven sampling rounds 

and approached background concentrations observed 

in the control area; however, median pH in the application area remained above 6, indicating that some acidneutralizing capacity was still present. Although 

notable changes in water quality were observed in 

interstitial waters during the study period, quality of 

ground water and spring water remained poor. Water 

from the Fleming site was not potable, given exceedances of primary and secondary Maximum Contaminant Levels (MCLs) for inorganic constituents in 

drinking water set by the U.S. Environmental Protection Agency. Only fluoride and sulfate, which were 

found in higher concentrations in application-area 

interstitial waters than in control-area interstitial 

waters, could be related to the PFBC by-product. Concentrations of arsenic, lead, and selenium typically 

were at or below the detection limits (generally 1 or 2 

micrograms per liter).

Elements detected at elevated concentrations in 

PFBC by-product application-area interstitial waters 

were not evident in downgradient ground water or 

spring water. Dilution of leachate by ground water was 

confirmed with a mixing model generated by the computer code NETPATH. Additionally, thermodynamic 

modeling of the chemical composition of water samples by use of the computer code PHREEQC indicated 

favorable conditions for precipitation of secondary 

minerals in the unsaturated zone and in aquifer materials. Because of low application rates of PFBC byproduct and precipitation and sorption of elements in 

the unsaturated zone, it is improbable that concentrations of any toxic elements of concern (arsenic, lead, 

or selenium) will exceed drinking-water standards at 

this site or other sites where similar volumes of PFBC 

by-products are used.
2 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

INTRODUCTION

The Clean Air Act of 1990 directs coal-burning utilities to 

reduce sulfur emissions by burning low-sulfur coal or by 

retrofitting with scrubbers that use a sorbent (limestone or 

dolostone) to remove sulfur from flue gases. The flue-gas 

desulfurization (FGD) process eliminates up to 99 percent 

of gaseous sulfur emissions, but it produces a solid by-product. Butalia and Wolfe (2000) estimated that, in Ohio, as 

much as 10 million tons of FGD and other coal-combustion 

by-products (CCBs) are generated each year. Eighty percent 

of CCBs are placed in landfills or surface impoundments, 

and the remaining 20 percent are used in application technologies. The costs (including trucking and landfilling fees) 

associated with disposal of CCBs are passed directly to the 

customers of the electric-power utility.

Beneficial uses are being sought for CCBs, including 

use as a soil amendment in the reclamation of abandoned 

coal mines. Many abandoned coal mines in Ohio and 

throughout the Appalachian coal region are characterized by 

acid mine drainage (AMD). These mines typically require 

alkaline amendments such as crushed limestone or agricultural lime to raise the pH of soil so that vegetation can be 

reestablished (Barton, 1978). Abandoned mine sites also 

commonly have very little topsoil, and what topsoil remains 

after mining may be of poor quality; so, soil amendments 

may be necessary to improve soil texture and water-holding 

properties. FGD by-products are desirable in this application because they are alkaline and typically have high calcium carbonate equivalents (Stehouwer and others, 1996). 

Additionally, some CCBs not only have a texture similar to 

that of silt loam but also may provide necessary elements to 

nutrient-deficient soils (Stehouwer and others, 1996). 

Therefore, a potential use exists for CCBs as a soil amendment. Before beneficial uses of FGD by-products will be 

supported by regulatory agencies and the electric-power 

industry, however, environmental data must be collected to 

show potential influences on water quality in the environmental settings of interest. Specifically, questions remain 

regarding the transport and fate of major elements such as 

sulfur and trace elements such as arsenic, lead, selenium, 

and boron that may be derived from the FGD by-product.

In late 1994, an abandoned surface coal mine in eastern Ohio (hereafter referred to as the “Fleming site”) was 

reclaimed with pressurized fluidized bed combustion 

(PFBC) by-product. Although the PFBC by-product used in 

this study is not strictly an FGD by-product, chemical reactions in the FGD process are similar to the PFBC process; 

thus, the PFBC by-product is chemically and physically 

comparable to FGD by-products. In addition to the PFBC 

by-product, yard-waste compost was added to the site to 

provide organic matter for establishment of vegetation. Site 

instrumentation and monitoring of the chemical character of 

unsaturated-zone water (hereafter referred to as “interstitial 

water”), ground water, and spring water began soon after 

reclamation to determine the mobility and fate of elements 

derived from the PFBC by-product. Grants from the Combustion Byproducts Recycling Consortium (a program of 

West Virginia University in cooperation with the U.S. 

Department of Energy National Energy Technology Center), the Ohio Department of Natural Resources Minerals 

Resources Management Division, and the Ohio Minelands 

Partnership provided support for collection and analysis of 

data presented in this report.

Purpose and scope

This report documents the effects of a surface application of 

dry PFBC by-product on water quality in the reclamation of 

an abandoned coal mine in Tuscarawas County, eastern 

Ohio. To evaluate the effects of addition of PFBC by-product and (or) reclamation on water, this report presents a 

summary of data collected from interstitial water, ground 

water, and spring water during the period September 1994 

through June 2001. Additionally, results of geochemical 

modeling are included to evaluate the potential fate of elements derived from the PFBC by-product. The report is limited to description of the site hydrology and its related water 

chemistry and to geochemical modeling of solid-phase and 

water samples.

Acknowledgments

Many individuals and agencies contributed to this work over 

the 7-year span of the project. In earlier years, the Ohio 

Department of Development Coal Development Office, 

Ohio Edison, Dravo Lime Company, The Ohio State University, American Electric Power, the U.S. Bureau of Mines, 

and the U.S. Department of Energy (Pittsburgh Energy 

Technology Center) were involved in the planning and 

financial support of the project. Special thanks go to the 

landowners, Donald Domer, Walter and Julie Randolph, and 

Lee Baumberger, for allowing data-collection activities at 

the Fleming site.

PREVIOUS INVESTIGATIONS

This report represents the culmination of a 7-year effort by 

the U.S. Geological Survey and The Ohio State University. 

Data and previous interpretations have been published in a 

series of technical reports, including Stehouwer and others 

(1996), Haefner (1998), and Dick and others (1999). The 

publication by Stehouwer and others (1996) includes chemical and physical characterization of PFBC by-product and 

other CCBs in Ohio. It also includes the results of greenhouse studies in which plant growth and leachate quality 

were examined with respect to varying application rates of 

CCBs. The reports by Haefner (1998) and Dick and others 
PREVIOUS INVESTIGATIONS 3

(1999) provide site characterization and water-quality data 

from the first 3 years of monitoring. These three reports are 

referenced extensively throughout this publication and are 

available for inspection at the U.S. Geological Survey Ohio 

District Office in Columbus, Ohio.

Abandoned mine sites have been reclaimed with soil 

amendments for many years in Ohio and throughout the 

United States. (See, for example, Skousen and others, 

1987.) The most common approach is to regrade the land to 

the approximate premining topographic contour, replace 

topsoil with soil taken from a borrow area, and apply agricultural lime (CaO) if the soil is too acidic. The land is then 

seeded with acid-tolerant plants (such as fescue) to encourage revegetation. Trees (pine and oak) also have been used 

in revegetation (Cordell and others, 2001). Other surface 

amendments include gypsum (CaSO4

.

2H2O), papermill byproducts, and waste materials derived from industrial processes and sewage sludge (Logan, 1992). 

Cunningham and Jones (1990) and Sedam and 

Francy (1993) describe the geochemistry of water in the 

Appalachian coal region of Ohio. These publications document elevated concentrations of iron and sulfur derived 

from the oxidation of pyrite contained in the coals and surrounding sedimentary rocks. Many other elements also are 

found in elevated concentrations in water from this region, 

including aluminum, chromium, manganese, nickel, and 

zinc. Surface-water pH in the Appalachian coal region is 

typically below 5 because of the hydrolysis reaction 

involved with the oxidation of ferrous iron (Fe2+) to ferric 

iron (Fe3+). The reaction results in precipitation of iron 

hydroxide (“yellow boy”) and the liberation of hydronium 

ions (H+). The low pH allows many pH-sensitive elements 

to remain in solution, resulting in elevated total dissolved 

solids concentrations and elevated specific conductance.

As the Clean Air Act of 1990 dictates, coal-burning 

utilities are required to reduce sulfur emissions. This has 

created a large amount of solid CCBs that are primarily disposed of in landfills. Monitoring at a FGD by-product landfill in Conesville, Ohio, indicated that leachate had elevated 

concentrations of sulfate and chloride (Hupe and Dziubek, 

1984). This landfill was used to dispose of wet FGD byproducts (as opposed to the dry PFBC material used in this 

study). The primary difference between wet FGD by-products and dry FGD by-products is that most of the sulfur in 

wet FGD by-products is present as sulfite (SO3

2-), whereas 

sulfur in dry FGD (and PFBC) by-products is present as sulfate (SO4

2-; Stehouwer and others, 1996). Water samples 

collected downgradient from the Conesville landfill over a 

3-year period intermittently exceeded the U.S. Environmental Protection Agency National Primary Drinking Water 

Regulations for arsenic, cadmium, chromium, and lead, and 

the National Secondary Drinking Water Regulations for sulfate (from oxidation of sulfite), total dissolved solids, and 

pH. Therefore, precedent exists for water-quality monitoring at sites that receive high volumes of these materials.

In light of available environmental data on FGD byproducts, additional applications are still being sought for 

abandoned mine reclamation, for agricultural uses, and for 

civil-engineering applications (Butalia and Wolfe, 2000; 

Stewart, 1997; Stehouwer and others, 1996). With regard to 

reclamation of abandoned coal mines, several efforts have 

been documented in Ohio. Stuart and Novak (2000) investigated the use of FGD by-products as a mine seal along a 

highwall left by coal mining. The main purpose of the 

project was to “remine” the area for remaining coal reserves 

and then eliminate AMD by reducing acidic discharge from 

mine portals left in the coal at the base of the highwall. The 

FGD by-product mine seal was successful in that acidic discharge from the mine was greatly decreased after reclamation. Correspondingly, iron and sulfate loading decreased 

during the study period. For this application, the use of FGD 

by-products as an impermeable seal precluded issues with 

degraded water quality. 

Use of FGD by-products as a grout in an underground mine in eastern Ohio was described by Mafi and 

others (1997). The objective of the project was to fill the 

mine void with FGD by-product grout and thereby limit 

oxygen availability and prevent pyrite oxidation. Although 

the initial volume of discharge from the mine decreased, a 

new hydrologic equilibrium was established that allowed 

water to flow elsewhere with little improvement in water 

quality. FGD by-products also were used to cap a coal 

refuse pile at the Rehoboth mine site in southeastern Ohio 

(Mafi, 1996). Slope-stability and erosion problems developed at the site after reclamation, compounded by elevated 

concentrations of boron at downgradient monitoring sites. 

The PFBC by-product used in this study was from an 

experimental test burn at a research facility in eastern Ohio; 

therefore, no other mine-reclamation applications of this or 

other PFBC by-products were identified in the literature. 

The mineralogy, solid-phase chemistry, and physical properties of the PFBC by-product were studied and described in 

detail by Stehouwer and others (1996); however, a short 

description of the solid-phase composition also will be 

given here. Grab-samples of the PFBC by-product and yardwaste compost were obtained immediately before application from piles of the materials stored onsite. The PFBC byproduct was dominated by calcium, magnesium, sulfate, and 

aluminum (table 1). Calcium and magnesium are derived 

from the dolomitic sorbent, resulting in a calcium carbonate 

equivalence as high as 60 percent (Stehouwer and others, 

1996). Sulfate originates from the coal (the Pittsburgh No. 

8) that was burned as the fuel source. The aluminum found 

in the PFBC by-product is derived from the fly-ash component of the by-product and originates from the clays and 

shales that are commonly associated with coal seams. 

Trace-element analysis of the PFBC by-product indicate 

that it contains elevated arsenic, boron, barium, chromium, 

nickel, lead, and selenium concentrations. For comparison, 

table 1 also includes maximum concentrations of trace 
4 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

elements in spoil and aquifer materials obtained from core 

samples reported in Dick and others (1999) and the composition of composted yard waste applied at the site. Boron 

was not quantified in the spoil and aquifer materials in this 

study; however, Botoman and Stith (1978) published boron 

analyses from Ohio coals, and their maximum value is 

included in table 1. These results indicate that, for many 

constituents, concentrations of elements can be higher in the 

mine spoil, aquifer materials, and compost than they are in 

the PFBC by-product. Comparison of PFBC by-product 

with the surrogate analysis of boron in coal from Botoman 

and Stith indicate that boron is found at greater concentrations in the PFBC by-product than in the coals.

Although applied at a rate of only 50 tons per acre 

over a 7-acre area, the compost may have been a significant 

source of chromium. Specific details of the source of materials used in the compost were not available, but compost 

typically contains grass clippings, leaves, and shredded 

wood from sources that might include treated pallets and 

telephone poles. The treatment of the wood involves 

chemicals that commonly contain trace elements including 

chromium. No further investigation was done regarding the 

organic chemistry of the compost; however, it should be 

noted that transport of elements such as cadmium, chromium, and copper might be enhanced by organic complexation.

STUDY METHODS

To investigate the effectiveness of a CCB as a mine-spoil 

reclamation amendment, an abandoned surface coal mine 

was reclaimed with PFBC by-product in 1994. Workers at 

The Ohio State University, School of Natural Resources, 

tested the mine spoil from the site and analyzed the PFBC 

by-product to determine that the mine spoil required 

approximately 125 tons per acre of PFBC by-product to 

attain a pH of 7 (Stehouwer and others, 1996). In addition, 

the mine spoil lacked organic matter necessary for successful plant growth, so approximately 50 tons per acre of yardwaste compost were added at the time of PFBC by-product 

application. The PFBC by-product and compost were 

applied to the regraded surface and were disked into the 

spoil during reclamation. The depth of incorporation was 

about 6 to 12 in. 

The Fleming site was instrumented after reclamation 

in late 1994 and in early 1995 so that water quality could be 

assessed through time. Data- and sample-collection activities included the following:

• Four core holes were drilled to define site 

stratigraphy and obtain lithologic samples for 

chemical analysis. 

• A precipitation station was established to 

collect wet and dry deposition for chemical 

analysis during a 1-year period (1995).

• Surface- and borehole-geophysical surveys 

were done to estimate the thickness of a 

surficial clay layer and further define site 

stratigraphy.

• Thirty-five soil-suction lysimeters in five 

clusters were installed to monitor interstitialwater quality within the shallow unsaturated 

zone. 

• Twenty monitoring wells in 13 well clusters 

were installed to monitor ground-water levels 

and water quality at depths ranging from 15 to 

100 ft. 

• Three sampling sites were established below 

downgradient springs to monitor the quality of 

spring water flowing from the site.

Soil-suction lysimeter clusters were installed in the 

PFBC by-product application area and outside of the application area (hereafter referred to as the “control area”). Reclamation within the control area was done by traditional 

Table 1. Solid-phase composition of PFBC by-product and 

maximum concentrations of constituents in mine spoil and 

aquifer materials from the Fleming abandoned mine site, 

Tuscarawas County, Ohio

[Modified from Haefner, 1998; --, not applicable]

Constituent PFBC

by-product

Yard-waste 

compost

Maximum 

concentration

in spoil 

and aquifer 

materials

Major Elements (weight percent)

Al 3.3 3.8 --

Ca 18 3.6 --

Fe 4.4 3.3 --

K 0.59 1.5 --

Mg 9.5 0.93 --

Mn 0.01 2.1 --

Na 0.10 0.52 --

S (as SO4) 4.9 <0.05 --

Total C 4.5 13 --

C, Organic 0.73 13 --

C, as CaCO3 3.8 0.41 --

Trace Elements (parts per million)

As 75 11 91

B 190 92 120a

a

 Botomon and Stith,1978.

Be 3 1 9

Ba 150 400 730

Cd <2 <2 <2

Cr 37 290 210

Ni 23 37 100

Pb 15 110 110

Se 1.3 6 21.5

Sr 160 130 720
STUDY METHODS 5

methods that included grading of spoil and applying a cover 

of approximately 1 ft of topsoil. The lysimeters were 

installed at depths ranging from 1.5 to 4.5 ft below the surface. Attempts were made to extract interstitial water from 

all lysimeters during each sampling round; however, small 

sample yields resulted in insufficient sample volumes for 

some analyses. Monitoring wells were installed at sites surrounding the PFBC by-product application area so that comparisons could be made between upgradient and 

downgradient water chemistry. Each of the wells was constructed of polyvinyl chloride casing material with 10-ft 

screens.

Water samples were collected from lysimeters, monitoring wells, and springs during the period 1995-2001. Six 

of the seven sampling rounds were done in June of each 

year during relatively dry periods, when base-flow conditions prevailed. One set of samples (interstitial-water sampling round 3) was collected in January, immediately after a 

snowmelt of approximately 11 in. Discharge of springs was 

measured at the time of each sampling round by means of 

volumetric techniques.

Onsite measurements of water characteristics 

included temperature, alkalinity, pH, reduction-oxidation 

(redox) potential, specific conductance, and dissolvedoxygen concentration by methods described in Wilde and 

others (1999). Measurements of ferrous iron (Fe2+), total 

iron, sulfate, hydrogen sulfide, and turbidity were made in 

the field by use of a portable spectrophotometer, in accordance with standard methods described in Walters (1989). 

Air temperature and air pressure were measured at the time 

of sampling. Water samples were analyzed in the laboratory 

by the methods described in Stehouwer and others (1996), 

Haefner (1998), and Dick and others (1999). Both the 

USGS National Water Quality Laboratory in Denver, Colo., 

and the Ohio Agricultural Research and Development Center (OARDC) Laboratory in the Department of Natural 

Resources in Wooster, Ohio, analyzed water samples for 

major and trace constituents. Water-quality constituents 

selected for analysis were based on the composition of 

PFBC by-product and acid mine drainage, as well as on 

anticipated water-rock interactions. Quality-assurance measures included submitting blank samples, replicate samples, 

and standard reference water samples (samples of known 

composition) to both laboratories. Discussion of qualityassurance results is given in Dick and others (1999).

The USGS Isotope Laboratory in Reston, Va., analyzed water samples for sulfur-isotope ratios (δ34S) in sulfate. Sulfur-isotope ratios are reported in parts per thousand 

(per mil) relative to the Canyon Diablo troilite (FeS) standard and have a reproducibility of +0.3 per mil. The ratio is 

calculated by the following equation:

. (1)

Sulfur-isotope ratios were measured to determine 

whether they could be used as a tool to trace leachate 

derived from PFBC by-product in an environment where 

water quality was already influenced by high concentrations 

of sulfate. Direct comparisons of sulfur-isotope ratios in sulfide and sulfate are possible because no significant fractionation occurs during the oxidation of sulfide minerals 

(Ohmoto and Rye, 1979; Taylor and others, 1984). Fractionation of sulfur isotopes upon precipitation of relatively soluble sulfate minerals was assumed to be negligible and has 

been estimated in the laboratory to be less than 2 per mil

(Thode and Monster, 1965).

For the purposes of this study, the dissolution and 

precipitation kinetics (rates of reactions) were assumed to 

be similar for all sulfur-bearing species with similar oxidation states. The primary form of sulfide at the mine site is 

pyrite, although minor amounts of marcasite (FeS2) also 

may be found. Oxidation of pyrite is relatively slow and 

may be rate-limited by available oxygen and water. Accelerated pyrite oxidation has likely been occurring since mining 

began at the site because of exposure to the atmosphere and 

increased surface area caused by disaggregation of overburden. With the addition of calcium from the PFBC by-product, the most abundant sulfate mineral in the unsaturated 

zone likely was gypsum (CaSO4·2H20), but alunite 

(KAl3(SO4)2(OH)6), basaluminite (Al4(SO4)(OH)10

·5H2O), ettringite (Ca6Al2(SO4)3(OH)12 ·26H2O), jarosite 

(KFe3(SO4)2(OH)6), melanterite (FeSO4·7H2O), rozenite 

(FeSO4·4H2O), schwertmannite (Fe16O16(OH)12 (SO4)2), 

and other variations also may be present (Jambor and others, 2000). These sulfate minerals are all fairly soluble, and 

their precipitation or dissolution does not significantly fractionate sulfur isotopes in water. 

The sulfur-isotope composition of sulfide minerals in 

spoil and aquifer materials is reported in Haefner (1998) 

and ranged from –26.3 to +13.6 per mil. The most negative 

values of δ34S are associated with strata that have the highest sulfur content; so, the dominant source of sulfate in 

water samples has relatively depleted values of δ34S 

(Haefner, 2001). For coal sequences, bacterial reduction of 

sulfate in sea water during deposition results in coal seams 

with sulfide that have isotope ratios ranging from –30 to 

+20 per mil (Thode and others, 1949). This wide range of 

sulfur-isotope ratios is most likely caused by infiltration of 

sulfate from seawater and nonmarine water. 

Two samples of PFBC by-product were analyzed for 

δ34S, and values of +4.6 and +4.8 per mil were determined 

(Haefner, 1998). These data, along with sulfur-isotope ratios 

in sulfide from aquifer materials, sulfate in rain water, interstitial water, ground water, and spring water, were combined 

to construct a sulfur-isotope mixing model for sulfate in 

water at the Fleming site (Haefner, 2001) following techniques outlined in Faure (1991). An advantage of using isotope ratios in mixing evaluations is that dilution or 

concentration does not affect isotope ratios, as opposed to 

δ34S

S S 32 ⁄ 34

sample S 34 Ss dard tan

32 ⁄ –

S Ss dard tan

32 ⁄ 34 = ------------------------------------------------------------------------------------------------- × 1000
6 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

concentrations (mass per unit volume) of individual constituents. Assumptions inherent in the sulfur-isotope mixing 

model are that the constituent under consideration is conservative, that only two components contribute sulfur to the 

system, and that the chemical and isotopic compositions of 

the end-members are constant (Faure, 1991). The isotopic 

composition of any mixture can be described as a straight 

line with the form 

, (2)

where δ34S is the isotope ratio in sulfate, Sm is the concentration of sulfate in the mixture, and a and b are constants 

specified by the concentrations and δ34S values of sulfate in 

the two end-members. Because the sulfate concentration in 

equation 2 is in the denominator, the inverse of sulfate was 

used for all subsequent mixing relations.

For the purposes of this report, results of data-collection activities are reported in the context of their relation to 

changes caused by reclamation and surface amendment with 

PFBC by-product. Other than reporting the median values 

of constituents, additional statistical computations were not 

done because the water-quality data were characterized by 

non-normal distributions, diverse sample-size populations, 

and changing detection limits between laboratories and 

sampling rounds. Helsel and Hirsch (1992) describe several 

statistical techniques to characterize censored data (data values below the reporting limit); however, these techniques 

generally require that the data fit an assumed distribution. 

To include all water samples in the median calculations and 

to provide insight into the “worst-case” maximum possible 

concentrations of constituents in water samples, values with 

concentrations less than the detection limit were substituted 

in all calculations without the less-than sign, providing estimates that are greater than the true value.

Water-quality and solid-phase data were used to construct geochemical models with the computer codes NETPATH (Plummer and others, 1994) and PHREEQC 

(Parkhurst and Appelo, 1999) to examine the fate of elements derived from the PFBC by-product. NETPATH computes the mixing proportions of several initial waters and 

the net geochemical reactions that can account for the 

observed composition of a final water. PHREEQC was used 

to evaluate whether thermodynamic conditions are favorable to either dissolve or precipitate secondary minerals.

HYDROGEOLOGIC SETTING

The Fleming site is within the Pottsville and Allegheny 

groups of Pennsylvanian-age sedimentary rocks of Tuscarawas County, eastern Ohio (fig. 1). The Lower Kittanning 

(No. 5) coal was mined from the site by surface operations 

over a 20-year period during about 1950-70. (Mining permits and records available from the Ohio Department of 

Natural Resources were not clear on the exact dates of mining.) The mining records indicate that a clay unit immediately beneath the Lower Kittanning coal also was mined 

during this period. The mine site was abandoned after 

depletion of the coal and clay reserves in the early 1970s. 

Soon thereafter, local residents began to lodge complaints 

regarding flooding and sedimentation along a nearby road. 

During a reconnaissance visit in early 1994, the author 

observed springs discharging AMD with pH less than 4 and 

high concentrations of dissolved solids, including iron 

and sulfate. 

Reclamation of the Fleming site was completed in 

the late summer and fall of 1994 by regrading the spoil to 

the approximate premining topographic contour and applying composted yard waste and PFBC by-product. Parallel 

studies by workers at the OARDC focused on surface-water 

runoff from six 1-acre test watersheds at the site (fig. 1). 

During reclamation and regrading, a continuous clay layer 

was installed beneath these watersheds to promote surfacewater runoff; thus, water quality from the test watersheds 

was not considered in this report. The reader is directed to 

Dick and others (1999) for more details on the results of the 

experiments at the test watersheds. 

The stratigraphy at the site is characterized by repeating sequences of sandstone, shale, limestone, coal, and 

underclay that dip slightly (1-2 degrees) to the southeast 

(fig. 2). The underclays act as a barrier to the downward 

movement of ground water; therefore, perched aquifers are 

common in these settings. As was the case for many other 

coal-related studies in Ohio, saturated zones are referred to 

as “aquifers” for convenience, even though they might only 

yield less than 1 gal/min to wells. Aquifers chosen for investigation in this study included the coals and sandstones 

immediately above the Brookville (No. 4) underclay and the 

Tionesta (No. 3b) underclay. These aquifers are hereafter 

referred to as the “shallow” and “deep” aquifers, respectively.

Ground-water-flow directions were documented 

through monthly water-level measurements in monitoring 

wells. Water levels were measured from January 1995 

through June 1998 and May 2000 through June 2001. The 

potentiometric surface for the shallow aquifer in June 2001 

is shown in figure 3. Flow directions in the shallow aquifer 

are from northwest to southeast; however, flow along the 

northern part of the Fleming site is from west to east. Water 

in the deep aquifer follows similar flow directions as those 

in the shallow aquifer. Hydrographs of water levels from 3 

wells at well cluster 4 indicate that water levels rose by as 

much as 4.5 ft during the study period. (Wells 4S and 4D 

were screened in the shallow and deep aquifer, respectively. 

Well 4D2 was screened in an aquifer below the deep aquifer 

and was the only well at the Fleming site screened in this 

b

S

a S

m

= + 34 δ
HYDROGEOLOGIC SETTING 7

Figure 1. Lysimeters, monitoring wells, and spring sites at the Fleming abandoned mine site, Tuscarawas County, Ohio. 

(Hydrogeologic section shown in figure 2).

1090

1110

1100

1080

1090

1080

1070

1070

1060

1060

1050

1040

1070

1060

1060

1070

1080

1050

A

A'

8

1

2

3

LC4

13

7

LC3

4

5

LC2

10

11 LC1

6

LC5

9

12

Dover

I-77

.

TU-120 TU-125

TU-124

Crossing Schneiders Road

Road

Mt. Pleasant

Study Area

OHIO Creek

Sugar

81o31'20"

40o

33'20"

40o

33'15"

81o

31'10"

EXPLANATION

PFBC by-product application area

Test watershed

Sediment pond

Line of hydrogeologic section

Topographic contour–Interval 2 feet.

Datum is sea level

Surface-water drainage

Core hole

Lysimeter cluster and identifier

Monitoring-well cluster and identifier

Spring-water site and identifier

LC1

1

TU-120

1060

A A'
8 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

Figure 2. Diagrammatic hydrogeologic section along A-A′ showing shallow and deep aquifer at the Fleming abandoned mine site, 

Tuscarawas County, Ohio.

A A'

North South

Monitoring well

Spoil

PFBC by-product application area

Lower Kittanning (No. 5) coal Underclay

Clarion Sandstone

Brookville (No. 4) coal Underclay

Homewood Sandstone

Tionesta (No. 3b) coal

Underclay

Sandstone

Upper Mercer (?) Shale

Shallow

Aquifer

Deep

Aquifer

Not to scale Stratigraphy modified from

Lamborn, 1956; Hull, 1990

Potentiometric surface

Ground-water flow direction

Spring

zone.) Water levels in all other wells followed a similar pattern as those in well cluster 4, except for well 5SP, which 

was 14 ft deep and was screened in the spoil. Water levels in 

well 5SP were below the screen bottom for most of 1995 but 

remained above the screen bottom for most of the study rose 

to within the screened interval in the spring of 1996 and 

period (Dick and others, 1999).

Over the 7-year period of water-level measurements, 

water-level rises were noted in all wells at the Fleming Site. 

Water-levels in wells 4D and 4D2 shown in figure 4 show a 

continuous rise throughout the study period; however, water 

levels in well 4S appear to have stabilized at an elevation of 

about 1,032 ft. Several factors may have combined to produce the observed rises during the study period. First, reclamation and the establishment of vegetation may have caused 

changes in the location and amount of recharge entering the 

shallow aquifer. Reduced runoff and increased infiltration 

are two desired effects of abandoned mine reclamation. The 

discharge areas (downgradient springs) were not altered 

before or during the course of this study. Second, the outlet 

elevation for a sediment pond southeast of well cluster 5 

was raised approximately 5 ft in early 1996, which may 

have resulted in higher water levels adjacent to the pond. 

Third, above-average rainfall during the 7-year period may 

have provided increased recharge to the water table. Average precipitation for eastern Ohio is approximately 38 in/yr; 

however, the cumulative total of rainfall from October 1994 

through September 2001 was 6.75 in above normal (table 2, 

Ohio Department of Natural Resources, 2002). Well 4S is 

the shallowest well of the cluster, and it appears to have 

responded to changes in the hydrologic system and equilibrated before wells 4D and 4D2.

 

The horizontal hydraulic conductivity of aquifers 

beneath the site was evaluated with single-well volume-displacement tests (slug tests) in 15 of the 20 wells (Haefner, 

1998). The hydraulic conductivity of the shallow aquifer 

from 33 tests on 8 wells ranged from 1 to 12 ft/d, whereas 

the hydraulic conductivity of the deep aquifer from 14 tests 

in 5 wells was 0.3 to 25 ft/d. Aquifer tests in similar 

Table 2. Rainfall amounts for the Northeast Hills, Ohio, 1993 

through 2001

[Summarized from Ohio Department of Natural Resources, 2002; water 

year begins on October 1 and ends on September 30]

Water

year

Measured

rainfall

(in inches)

Departure

from

average of

38 inches

(in inches)

Cumulative

total

departure

(in inches)

1993 42.77 +4.77 +4.77

1994 32.40 -5.60 -0.83

1995 46.14 +8.14 +7.31

1996 39.41 +1.41 +8.72

1997 40.55 +2.55 +11.27

1998 36.19 -1.81 +9.46

1999 41.56 +3.56 +13.02

2000 31.72 -6.28 +6.74
HYDROGEOLOGIC SETTING 9

Figure 3. Potentiometric surface in the shallow aquifer on June 25, 2001, at the Fleming abandoned mine site, Tuscarawas County, Ohio.

1090

1110

1100

1080

1090

1080

1070

1070

1060

1060

1050

1040

1070

1060

1060

1070

1080

1050

1036

1035

1034

1033

8

1036.02

1

1036.06

2

1035.7

3

1032.69

13

1035.55

7

1034.96

4

1032.36

5

1032.4

10

1033.23

11

1035.57 6

1035.43

9

1034.68

12

1035.41

Dover

I-77

.

TU-120 TU-125

TU-124

Crossing Schneiders Road

Road

Mt. Pleasant

Study Area

OHIO Creek Sugar

81o31'20"

40o

33'20"

40o

33'15"

81o

31'10"

EXPLANATION

PFBC by-product application area

Test watershed

Sediment pond

Water-level contour–Interval 1 foot. Dashed

where approximate. Datum is sea level

Topographic contour–Interval 2 feet.

Datum is sea level

Surface-water drainage

Monitoring well, identifier, and water level

Spring-water site and identifier

1

1036.06

TU-120

1035

1060
10 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

Figure 4. Water levels and precipitation from cluster 4, Fleming abandoned mine site, Tuscarawas County, Ohio. (Precipitation 

data from Ohio Department of Natural Resources, 2002).

1,029

1,030

1,031

1,032

1,033

1,034

1,035

1,005

1,006

1,007

1,008

1,009

1,010

1,011

WATER-LEVEL ELEVATION, IN FEET

979

980

981

982

983

984

985

Jun-95 Jun-96 Jun-97 Jun-98 Jun-99 Jun-00 Jun-01

0

1

2

3

4

5

6

7

8

Jun-95 Dec-95 Jun-96 Dec-96 Jun-97 Dec-97 Jun-98 Dec-98 Jun-99 Dec-99 Jun-00 Dec-00 Jun-01

PRECIPITATION,

IN INCHES

WELL 4S

Depth 44 feet

WELL 4D

Depth 61.5 feet

WELL 4D2

Depth 98 feet

coal-related aquifers in Coshocton, Jefferson, and Muskingum Counties within the Middle Kittanning (No. 6), the 

Waynesburg (No. 11), and the Meigs Creek (No. 9) coals 

indicated values ranging from 0.1 to 150 ft/d (Bonta and 

others, 1992). Hobba (1991) tested an aquifer in the Upper 

Freeport coal in West Virginia and computed hydraulic conductivity of 11.8 to 13.6 ft/d. Aquifer tests by Martin and 

others (1990) from aquifers within Indiana coal sequences 

resulted in ranges of 0.0002 to 0.8 ft/d. The wide ranges of 

hydraulic conductivities are likely the result of the diversity 

of rock types in coal sequences. Coal beds have fractures 

(cleats) that enhance hydraulic conductivity, whereas 
HYDROGEOLOGIC SETTING 11

Table 3. Discharge measurements at three spring sites at the Fleming abandoned mine site, Tuscarawas County, Ohio

All measurements were made using volumetric techniques and are in cubic feet per second; --, measurement not done; <, actual

value is less than that indicated]

Sitea Date of measurement

June 1995 June 1996 June 1997 June 1998 June 2000 June 2001

TU-120 0.045 0.072 0.095 --b -- --

TU-124 .005 .008 .010 0.020 0.012 0.013

TU-125 .007 .008 .016 .008 <.001 .004

a

 Site location shown on inset map on figure 1.

b Site TU-120 was altered by installation of a nearby pond in early 1998; therefore, no subsequent samples or discharge 

measurements were made.

shales, underclays, and some of the tighter sandstones may 

have lower values of hydraulic conductivity. Springs discharge into a small system of streams along the south border 

of the site (fig. 1). These springs discharge from the shallow 

aquifer. Discharge was measured only at times corresponding to water-quality sampling (during base flow) and ranged 

from less than 0.001 ft3/s at TU-125 to 0.095 ft3/s at TU120 (less than 0.45 to 43 gal/min; table 3).

Conceptually, precipitation at the Fleming Site can 

either infiltrate into the unsaturated zone through pores in 

the spoil and aquifer materials or run off the surface and be 

collected in one of the four sediment-detention ponds onsite 

(fig. 1). Water that infiltrates into the spoil (and through 

PFBC by-product) may react with soluble components, dissolve them, and transport them down to the water table. 

Because the PFBC by-product was applied to the surface 

and incorporated into the spoil, water was not expected to 

flow any differently in the application area than in the control area. Water in the unsaturated zone moves downward 

only under the force of gravity and could potentially evaporate, precipitate secondary minerals (such as sulfate salts 

and iron and aluminum hydroxides), and (or) percolate 

down to the water table. The ground-water quality at this 

and most other AMD sites is influenced most strongly by 

chemical reactions in the unsaturated zone. These reactions 

most typically involve oxidation and dissolution of minerals 

from the spoil. Because the site sits on a hilltop, the water 

flows away from topographic highs and discharges to downgradient springs along the hillside.

The conceptualization of the flow system and the 

data obtained from wells, core samples, and surface geophysical surveys, were combined to construct a threedimensional ground-water-flow model documented in 

Haefner (1998). The objectives of the model were to simulate ground-water-flow directions and estimate advective 

traveltimes of particles of water from the water table 

beneath the PFBC by-product application area to spring discharge areas. The model was calibrated to head and flow 

conditions measured in June 1996 and included a recharge 

rate of 5.1 in/yr over the entire modeled area. If water-level 

rises in wells at the site were caused by additional recharge 

entering the system (as postulated for the rise in water levels 

observed at the Fleming site), then the recharge estimate of 

5.1 in/yr represents a minimum value because additional 

recharge would be required to increase the amount of water 

held in storage. Particle-tracking simulations provided estimated traveltimes of 227 days to 27 years for water to move 

through the system (Haefner, 1998).

Ground-water-flow-modeling simulation results were 

substantiated by analyses of tritium (3H) in ground water. At 

the beginning of this study, it was not known whether 

recharge rates were fast enough or traveltimes were short 

enough to detect water-quality changes after application of 

PFBC by-product on the land surface. Tritium is produced 

naturally in the upper atmosphere as a result of interactions 

of cosmic-ray-produced neutrons with nitrogen atoms. Estimated concentrations of naturally occurring tritium in precipitation are as high as 20 tritium units (TU, 1 TU equals 

one atom of 3

H in 1018 atoms of 1H). The onset of thermonuclear bomb testing in the early 1950s, however, produced 

a tritium peak with concentrations up to 1,000 TU, providing a qualitative mechanism to estimate the approximate age 

of ground-water recharge. All ground-water samples had tritium concentrations greater than 4 TU, and water samples 

from most wells had greater than 20 TU (fig. 5).

Figure 5. Tritium concentration as a function of depth for 

ground-water samples colllected in 1995 at the Fleming 

abandoned mine site, Tuscarawas County, Ohio.

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80

TRITIUM CONCENTRATION,

IN TRITIUM UNITS

DEPTH FROM LAND SURFACE

TO MIDDLE OF SCREEN INTERVAL,

IN FEET

Shallow aquifer

Deep aquifer
12 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

Because tritium has a half-life of 12.43 years, Fontes (1980) 

asserted that any ground waters with detectable concentrations of tritium were recharged after 1952. Results of analyses of ground-water samples from the Fleming site indicate 

that water recharged after the early 1950s had mixed with 

ambient ground water (Haefner, 1998). The traveltime of 

water through the unsaturated zone (precipitation as rain or 

snow on land surface to the water table) was not evaluated.

The water-table gradient on the north side of the site 

is relatively gentle, but it steepens closer to the southern part 

of the site (fig. 3). Accordingly, ground-water velocity is 

relatively faster through the southern part of the site. This 

steepening of the gradient is likely caused by stress-relief 

fractures along the hillside, as noted at other mine sites 

throughout the Appalachian coal region (Bonta and others, 

1992; Saad and Cravotta, 1991; Hobba, 1991).

WATER QUALITY

In terms of surface revegetation and reduction of erosion, 

reclamation of the Fleming site with PFBC by-product and 

yard-waste compost was almost immediately successful 

(Dick and others, 1999). The fescue and alfalfa planted at 

the site established itself during the first growing season 

(1995) and continued to reseed itself during the course of 

this study (through 2001). In contrast, water-quality 

improvements from reclamation of abandoned mine sites 

are known to take many years (Eberle and Razem, 1985; 

Cunningham and Jones, 1990). To evaluate the water quality 

at the Fleming site, water samples were collected from the 

shallow unsaturated zone, ground water, and springs over 7 

years of study. Major findings are summarized in graphs, 

tables, and text in the next few pages of this report. Supporting data from all sampling rounds are given in Stehouwer 

and others (1996), Haefner (1998), Dick and others (1999), 

and Shindel and others (2001, 2002) and are not 

reproduced here. 

Haefner (1998) and Dick and others (1999) describe 

the properties and constituents that can be used to evaluate 

differences between waters that have been influenced by 

leachate derived from PFBC by-product from those that 

were not. These include specific conductance, pH, selected 

major ions and trace elements (calcium, magnesium, sulfate, and boron), magnesium-to-calcium (Mg:Ca) mole 

ratios, and sulfur-isotope ratios (δ34S). Several comparisons 

are included in this report to summarize the effects of PFBC 

by-product leachate on water quality, including:

• median values of water-quality characteristics 

in application-area and control-area 

interstitial water,

• median values of these characteristics in 

upgradient ground water, downgradient 

ground water, and spring water,

• median values for selected characteristics in 

different matrices for each sampling round, 

presented as a series of bar graphs,

• graphs of sulfate concentrations as a function 

of magnesium-to-calcium mole ratios and 

sulfur-isotope ratios, and

• comparisons of water-quality results with U.S. 

Environmental Protection Agency Maximum 

Contaminant Levels (MCLs) for 

drinking water.

Waters from abandoned surface coal mines in Ohio 

have been generally categorized as calcium-sulfate type 

waters (Sedam and Francy, 1993). Because magnesium concentrations are approximately equal to calcium concentrations, water samples from the Fleming site are calciummagnesium-sulfate type waters. When the Fleming site 

samples are represented on a standard Piper trilinear diagram, the high concentrations of sulfate and low concentrations of sodium in these waters cause most of the data points 

to be densely clustered towards the sulfate end-member and 

the calcium and magnesium axes (fig. 6A). To allow for 

greater differentiation, the standard Piper diagram shown in 

figure 6A was modified to include different cations and 

anions, and multipliers were applied to distinguish water 

types (fig. 6B). Modifications included changing the cation 

end-members to calcium plus magnesium (Ca + Mg), iron 

plus aluminum (Fe + Al), and sodium plus potassium (Na+ 

K) multiplied by 10. Anion end-members were modified to 

include fluoride (F) multiplied by 10, chloride (Cl), and sulfate (SO4) multiplied by 0.01. When plotted this way, most 

application-area interstitial waters can be distinguished 

from all other water samples because their calcium and 

magnesium concentrations were much greater than those for 

other water samples. (Not all water samples are included in 

figures 6A and 6B because of incomplete analyses for 

some samples.)

Median values of all water-quality characteristics 

were computed for the five different water matrices (application-area interstitial water, control-area interstitial water, 

upgradient ground water, downgradient ground water, and 

spring water; table 4). The median values of most characteristics clearly show the influence of PFBC by-product 

leachate on application-area interstitial waters. The median 

specific conductance in application-area interstitial waters 

was 5,500 μS/cm as compared to 1,900 μS/cm for controlarea interstitial waters. The neutralizing effect of the PFBC 

by-product can be seen in median alkalinity and hardness in 

interstitial waters, which were more than 5 times greater in 

the application area than in the control area. The median pH 

of application-area interstitial waters was 6.6 as compared 

to 5.0 for the control area. Median concentrations of major 

elements such as calcium, magnesium, and sulfur (as sulfate) were greater in application-area interstitial waters than 

in control-area interstitial waters. The median concentrations of boron, chloride, fluoride, potassium, and strontium 
WATER QUALITY 13

Figure 6. Standard and modified piper trilinear diagrams of selected water samples from the Fleming abandoned mine site, 

Tuscarawas County, Ohio. (See discussion in text for description of modifications.)

EXPLANATION

Upgradient ground water

Downgradient ground water

Spring water

Application-area interstitial water

Control-area interstitial water

2 0

4 0

6 0

8 0

2 0

4 0

6 0

8 0 8 0

6 0

4 0

2 0

20

4 0

6 0

8 0

20

40

60

80

0

100 100

0

100

0

BICARBONATE

SODIUM

CALCIUM + MAGNESIUM

0

100

CHLORIDE

100

8 0

6 0

4 0

2 0

0

CALCIUM

0

100

MAGNESI

PERCENTAGE OF MILLIEQUIVALEN

UM

TS

PERCENTAGE OF MILLIEQUIVALENTS

PERCENTAGE OF MILLIEQUIVALENTS

Cations Anions

A.

STANDARD

DIAGRAM SULFATE + CHLORIDE

SULFATE

20

40

60

80

0

100

20

40

60

80

0

100

20

4 0

6 0

8 0

100

0

20

4 0

6 0

8 0

100

0

Ca

Ca

Mg

Mg

Ca

Mg

Na

Na

Mg

Ca Na

Na

SO4

SO4

Cl

HCO Cl 3

Cl

HCO3

Cl

HCO3

SO4

HCO3

SO4

2 0

4 0

6 0

8 0

2 0

4 0

6 0

8 0 8 0

6 0

4 0

2 0

20

4 0

6 0

8 0

20

40

60

80

0

100 100

0

100

0

SULFATE x 0.01

(SODIUM + POTASSIUM) x 10

+ CALCIUM + MAGNESIUM

CHLORIDE

0

100

FLUORIDE x 10

100

8 0

6 0

4 0

2 0

0

CALCIUM + MAGNESIUM

0

100

(SODIUM + POTASSIUM) x 10

PERCENTAGE OF MILLIEQUIVALENTS

PERCENTAGE OF MILLIEQUIVALENTS

PERCENTAGE OF MILLIEQUIVALENTS

Cations Anions

B.

MODIFIED

DIAGRAM

20

40

60

80

0

100

20

40

60

80

0

100

20

4 0

6 0

8 0

100

0

20

4 0

6 0

8 0

100

0

SULFATE x 0.01

+ CHLORIDE

IRON + ALUMINUM
14 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

Table 4. Median values of water-quality characteristics from selected water samples collected at the Fleming abandoned mine site, 

Tuscarawas County, Ohio

[Number of samples used to compute each median is given in parentheses; mg/L, milligrams per liter; redox, reduction-oxidation potential; μS/cm, 

microsiemens per centimeter; μg/L, micrograms per liter; --, not measured; per mil, parts per thousand relative to a standard]

Property

 or

constituent

Units

Interstitial water Ground water

Spring

water Application 

area

Control

area

Upgradient Downgradient

Onsite Measurements and Analyses

Alkalinity mg/L as CaCO3 195 (6) 35 (1) 68 (27) 52 (26) 5.0 (1)

Oxygen, dissolved mg/L -- (0) -- (0) <0.1 (23) <0.1 (22) 7.3 (5)

pH standard units 6.6 (113) 5.0 (18) 5.6 (27) 5.5 (26) 3.6 (6)

Redox millivolts -- (0) -- (0) 160 (27) 200 (26) 590 (5)

Specific conductance μS/cm 5,500 (113) 1,900 (19) 3,100 (27) 3,100 (26) 1,400 (6)

Temperature degrees Celsius -- (0) -- (0) 13.0 (27) 13.0 (26) 22.5 (6)

Laboratory Analyses (all values are for the dissolved (filtered) fraction)

Acidity mg/L as CaCO3 0.5 (30) 0.0 (3) 11.5 (19) 10.9 (18) 0.6 (4)

Dissolved solids mg/L 10,430 (31) -- (0) 3,290 (27) 3,400 (26) 1,100 (5)

Hardness mg/L as CaCO3 5,800 (76) 900 (15) 1,700 (27) 1,800 (26) 750 (6)

Aluminum mg/L 280 (61) 300 (9) 87 (27) 240 (26) 1,500 (4)

Antimony μg/L <106 (51) <106 (5) <106 (19) <106 (18) <106 (5)

Arsenic μg/L <2.0 (39) <2.0 (11) <1.0 (27) <2.0 (26) <1.0 (6)

Barium μg/L 15 (51) 16 (5) 20 (19) 13 (18) 22 (4)

Berrylium μg/L <1 (51) 2 (5) 3 (19) 4 (18) 2 (4)

Boron μg/L 690 (77) 65 (14) 280 (27) 300 (26) 220 (6)

Bromide μg/L <0.10 (10) <0.10 (4) .58 (8) .50 (8) <0.01 (2)

Cadmium μg/L 1 (61) 3 (9) 4 (27) 5 (26) 3 (6)

Calcium mg/L 430 (77) 180 (15) 360 (27) 370 (26) 150 (6)

Chloride mg/L 39 (66) 7.4 (14) 2.2 (27) 3.5 (26) 3.0 (6)

Chromium μg/L 11 (61) 10 (9) 4 (27) 6 (26) 6 (6)

Cobalt μg/L 80 (61) 120 (9) 200 (27) 270 (26) 90 (6)

Copper μg/L 23 (61) 11 (9) <2 (27) <2 (26) 3.5 (6)

Fluoride mg/L 1.6 (66) 0.45 (14) <0.10 (27) <0.10 (26) 1.1 (6)

Iron mg/L .078(77) 12 (15) 270 (27) 280 (26) 1.6 (6)

Lead μg/L <2 (49) <1 (12) <1 (27) <2 (26) <1 (6)

Lithium μg/L 110 (61) 140 (9) 150 (27) 220 (26) 110 (6)

Magnesium mg/L 1,200 (77) 100 (15) 200 (27) 210 (26) 91 (6)

Manganese mg/L 19 (77) 15 (15) 17 (27) 19 (26) 6.0 (6)

Mercury μg/L <0.1 (24) <0.1 (3) <0.1 (6) <0.1 (6) <0.1 (1)

Molybdenum μg/L <11 (51) <7 (5) <11 (19) <11 (18) <11 (4)

Nickel μg/L 160 (61) 460 (9) 420 (27) 490 (26) 180 (6)

Nitrogen, as NH4 mg/L 0.13 (27) 0.92 (3) 1.0 (26) 0.95 (25) 0.15 (6)

Nitrogen, as NO2 mg/L <0.01 (27) <0.01 (3) <0.01 (26) <0.01 (25) <0.01 (6)

Nitrogen, as NO2 + NO3 mg/L 0.06 (27) 0.06 (3) <0.05 (26) <0.05 (25) <0.05 (6)

Phosphorous, as PO4 mg/L <0.01 (27) <0.01 (3) 0.02 (26) 0.02 (25) <0.01 (6)

Potassium mg/L 47 (67) 16 (12) 13 (27) 11 (26) 6.2 (6)

Selenium μg/L <3 (36) <1 (11) <1 (26) <1 (26) <1 (6)

Silica, as SiO2 mg/L 29 (77) 32 (15) 11 (27) 11 (26) 10 (6)

Silver mg/L <10 (61) <10 (9) <10 (27) <10 (26) <6 (6)

Sodium mg/L 44 (77) 34 (15) 11 (27) 10 (26) 3.4 (6)

Strontium μg/L 750 (61) 300 (9) 2,800 (27) 2,800 (26) 490 (6)

Sulfate mg/L 4,800 (66) 970 (14) 2,200 (27) 2,200 (26) 810 (6)

Vanadium μg/L 17 (61) 10 (9) 6 (27) 7 (26) 8 (6)

Zinc mg/L 74 (61) 310 (9) 310 (27) 540 (26) 200 (6)

Carbon, organic mg/L 23 (18) 5.7 (2) 0.7 (26) 1.0 (26) 1.2 (6)

δ34S in sulfate per mil -4.1 (69) -14.5 (14) -10.2 (27) -10.1 (26) -9.95 (6)
WATER QUALITY 15

also were greater in the application-area interstitial waters 

than in the control area. Elevated concentrations of boron 

may be of concern because at concentrations approaching 

10 mg/L, boron is known to be phytotoxic (Pierzinski and 

others, 1994). The greatest concentration of boron (1.7

mg/L) was detected in a sample of interstitial water in the 

PFBC by-product application area during sampling round 3. 

For many of the trace elements of concern (including 

arsenic, lead, and selenium), the concentrations in most of 

samples were at or below the detection limit (generally less 

than 2 μg/L). Elements that have lower median concentrations in application-area interstitial waters than in controlarea interstitial waters include iron, nickel, and zinc, presumably because of pH dependence on the solubility of 

these elements and their related solid phases. The median 

δ34S in dissolved sulfate for waters from the applicationarea interstitial waters was –4.1 per mil, whereas the median 

δ34S for control-area interstitial waters was –14.5 per mil 

(table 4). The relatively higher sulfur-isotope ratios in application-area interstitial waters reflect the influence of the 

positive δ34S of the PFBC by-product. 

Median values of most characteristics in samples of 

downgradient ground waters are approximately equal to or 

greater than those in upgradient ground waters (table 4). 

Consequently, upgradient and downgradient waters are both 

influenced by similar geochemical processes. The median 

value for sulfur (as sulfate) was 2,200 mg/L for upgradient 

and downgradient ground-water samples alike. Measurements for sulfide made with a field spectrophotometer indicated that only trace amounts of sulfide (<0.001 + 0.003 

mg/L) were present in ground water. Aluminum, nickel, and 

zinc were found in greater concentrations in downgradient 

ground waters, presumably because of the influence of mining and reclamation activities at the Fleming site. Calcium, 

magnesium, and chloride increased slightly between upgradient and downgradient ground-water sampling sites, a possible indication that leachate from the PFBC by-product has 

mixed with downgradient ground water.

Concentrations of almost all major ions, nutrients, 

and trace elements decreased between downgradient 

ground water and spring water except for aluminum, which 

increased by a factor of more than six (240 μg/L to 1,500 

μg/L). At pH less than 4.5, the solubility of aluminum 

increases dramatically (Hem, 1992; Hamlin and Alpers, 

1996). Median pH in spring water was 3.6 but varied considerably throughout the study period, from a minimum of 

3.2 to a maximum of 5.5 among six samples. Measurements of pH at TU-125 (which was outside the PFBC byproduct application area watershed) ranged from 5.3 to 6.5 

for six samples collected on the same date as other spring 

samples. Large decreases of median concentrations 

between downgradient ground water and spring water were 

noted in elements related to AMD, including iron, manganese, nickel, and zinc. Constituents associated with the 

PFBC by-product, including boron, calcium, and magnesium, also decreased between downgradient ground water 

and spring water. Sulfur-isotope ratios of sulfate in spring 

water were virtually the same as ratios in both upgradient 

and downgradient ground waters and represent the relatively negative isotopic composition of aquifer materials 

and spoil oxidation.

The analysis of median values of characteristics for 

all water samples, regardless of sampling round, is useful if 

there are no trends or changes in water quality through time 

but becomes less meaningful otherwise. Therefore, bar 

graphs of median values of selected water-quality characteristics by sampling round are shown in figures 7 and 8. For 

interstitial-water sampling rounds 1 and 2, insufficient water 

was obtained from the lysimeters; therefore, data are not 

shown for some characteristics. For interstitial waters (fig. 

7), each of the bar graphs shows a distinct difference 

between medians obtained in the PFBC by-product application area and those in the control area. For the graphs of specific conductance, magnesium-to-calcium (Mg:Ca) mole 

ratios, sulfate, and sulfur-isotope ratios, the greatest median 

values obtained from interstitial water within the PFBC byapplication area were observed in sampling rounds 2 or 3. 

For each subsequent sampling round, medians for these 

characteristics in the application-area interstitial waters 

approach those for the control area. The trends observed in 

median values from application-area interstitial waters during the seven sampling rounds is likely a result of the influence of leaching and depletion of soluble elements derived 

from the PFBC by-product through time. Similar relations 

were observed in greenhouse studies reported in Stehouwer 

and others (1996). 

The patterns in the bar graphs for the same characteristics in ground water and spring water are different than 

those for the interstitial waters (fig. 8). For most sampling 

rounds, median values in upgradient ground waters were 

similar to downgradient ground waters; therefore, table 4 

may represent these data adequately for many constituents. 

However, median values of Mg:Ca mole ratios were consistently greater in downgradient ground waters. As seen in 

figure 7, Mg:Ca mole ratios were higher in application-area 

interstitial waters than control-area interstitial waters; therefore, elevated Mg:Ca mole ratios in downgradient ground 

waters may provide additional evidence that leachate from 

the PFBC by-product has reached ground water. 

The median values of δ34S in both upgradient and 

downgradient ground water for seven sampling rounds show 

that the isotope ratios are greatest during the early sampling 

rounds, but then become more negative in later sampling 

rounds (fig. 8). This is in contrast to median sulfate concentrations, which increase to a maximum value during round 

5. Therefore, an additional source of sulfate must have been 

reaching ground water. If the source of increased sulfate in 

ground water was from PFBC by-product leachate, the sulfur-isotope ratio should increase (become less negative). 

Spoil and aquifer materials at the Fleming site have
16 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

Figure 7. Median pH, specific conductance, boron, magnesium-to-calcium mole ratios, sulfate, and sulfur-isotope ratios for 

interstitial waters for each sampling round from the Fleming abandoned mine site, Tuscarawas County, Ohio.

4

5

6

7

pH,

IN STANDARD UNITS

0

2,000

4,000

6,000

8,000

10,000

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS

PER CENTIMETER

0

200

400

600

800

1,000

BORON,

IN MICROGRAMS PER LITER

0

1

2

3

4

5

6

7

MAGNESIUM-TO-CALCIUM

MOLE RATIO

(Dimensionless)

0

2,000

4,000

6,000

8,000

1234567

SULFATE,

IN MILLIGRAMS PER LITER

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

1234567

SAMPLING ROUND

SULFUR-ISOTOPE RATIO,

IN PER MIL

Application-area interstitial water

Control-area interstitial water

EXPLANATION

NOTE: No data where bars are absent

SAMPLING ROUND

relatively negative values of δ34S. The likely source of 

increased sulfate in ground water is the disturbance of mine 

spoils during reclamation, not the PFBC by-product. 

These results indicate that the quality of interstitial 

water within the PFBC by-product application area has been 

influenced by leachate derived from the PFBC by-product. 

The only improvements in interstitial-water quality that can 

be directly attributed to the PFBC by-product include 

increased pH and reduction in the concentrations of 

dissolved iron, nickel, and zinc. Median pH obtained from 

the application-area interstitial waters remained above 6.0 

for all sampling rounds, indicating that at least some acid 

neutralizing capacity remained 7 years after application; 

however, bar graphs of interstitial water (fig. 7) show that
WATER QUALITY 17

Figure 8. Median pH, specific conductance, boron, magnesium-to-calcium mole ratios, sulfate, and sulfur-isotope ratios for 

ground and spring waters for each sampling round from the Fleming abandoned mine site, Tuscarawas County, Ohio.

6

pH,

IN STANDARD UNITS

0

1,000

2,000

3,000

4,000

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS

PER CENTIMETER

0

100

200

300

400

500

BORON,

IN MICROGRAMS PER LITER

0

1

2

MAGNESIUM-TO-CALCIUM

MOLE RATIO

(Dimensionless)

0

1,000

2,000

3,000

1234567

SAMPLING ROUND

SULFATE,

IN MILLIGRAMS PER LITER

-15

-10

-5

0

1234567

SAMPLING ROUND

SULFUR-ISOTOPE RATIO,

IN PER MIL

Upgradient ground water

Downgradient ground water

Spring water

EXPLANATION

NOTE: No data where bars are absent

5

4

3

many of the elements derived from the PFBC by-product 

have been leached to concentrations approaching the background concentrations observed in the control area. Downgradient ground-water quality and spring-water quality 

remain poor and show no sign of improvement 7 years after 

reclamation.

Chemical tracers of PFBC by-product

In addition to the Piper diagrams shown in figure 6 and the 

bar graphs in figures 7 and 8, two additional plotting techniques were used to differentiate waters that contain PFBC 

by-product from waters that are influenced by AMD and the 

aquifer materials. A scatterplot of sulfate concentration with 

respect to Mg:Ca mole ratios shows the difference between 

waters influenced by PFBC by-product leachate and all 
18 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

other water samples (fig. 9). Samples of interstitial water 

from the application area typically have Mg:Ca mole ratios 

greater than 1, whereas most other water samples from the 

site have ratios approximately equal to or less than 1. As 

noted previously, downgradient ground waters have slightly 

higher Mg:Ca mole ratios than upgradient ground waters. 

The median Mg:Ca mole ratio of all upgradient groundwater samples was 0.89 as compared to 0.95 for downgradient ground waters.

A scatterplot of the inverse of sulfate with respect to 

δ34S also shows a difference between water samples influenced by PFBC by-product leachate and those that are not 

(fig. 10). These relations were used in an isotope-mixing 

model reported in Haefner (2001). To estimate the abundance of sulfate derived from PFBC by-product in interstitial waters, an equation for the relation between the inverse 

of sulfate and δ34S was computed for the most concentrated 

samples by use of least-squares regression. The regression

Figure 9. Relation of sulfate concentration to magnesium-to-calcium mole ratios for selected water samples from the Fleming 

abandoned mine site, Tuscarawas County, Ohio.

0

2

4

6

8

10

12

14

16

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

SULFATE, IN MILLIGRAMS PER LITER

MAGNESIUM-TO-CALCIUM MOLE RATIO

(Dimensionless)

0

1

2

0 1,000 2,000 3,000

Upgradient ground water

Downgradient ground water

Spring water

Application-area interstitial water

Control-area interstitial water
WATER QUALITY 19

line was generated for a selected set of water samples only 

and does not include data from the end-members. The 

regression analysis resulted in the following 

mixing equation:

 . (3)

Estimates based on a positive δ34S value of the PFBC 

by-product (+4.8 per mil) as one end-member and the most 

negative value of δ34S from control-area interstitial waters 

(-16.6 per mil) as the other end-member indicate that as 

much as 75 percent of the sulfate in application-area interstitial waters was derived from the PFBC by-product 

leachate during interstitial-water sampling round 3 (January 

1996). The contribution of sulfate from the PFBC by-product has decreased from 75 percent in round three to a 

median value of about 20 percent in round 7 (June 2001). 

The process responsible for this decrease is leaching and 

subsequent depletion of the soluble sulfate minerals within 

the PFBC by-product. This same analysis was done for 

ground-water samples; however, sulfur-isotope ratios in 

upgradient and downgradient ground waters show that sulfate in ground water was derived from spoil and aquifer 

materials, not PFBC by-product.

The primary reason that these graphical techniques 

allow distinction between the waters influenced by leachate 

derived from the PFBC by-product and waters that were not 

is that the coal burned (Pittsburgh No. 8) and the sorbent 

used (dolomite from northwest Ohio) in the PFBC process 

were from different formations than those at the Fleming 

site. These methods may not prove as successful in haulback situations, where coal and (or) the sorbent were taken 

from the same mine where the by-product is placed. Therefore, if interstitial water containing leachate from the PFBC 

by-product were mixing with ground water from the Fleming site, we should see increasing δ34S ratios approaching 

+4.8 per mil and increasing Mg:Ca ratios above 1.0 in 

downgradient ground-water samples.

Comparisons of water-quality data to established 

drinking-water standards

To put the water-quality data collected in this study 

in context with established drinking-water regulations, comparisons to the U.S. Environmental Protection Agency 

(2002) list of Maximum Contaminant Levels (MCLs) are 

provided in table 5. This table includes data from all water 

samples collected during the study. Many primary and secondary MCLs were exceeded in the waters collected at the 

Fleming mine site. The primary standards for beryllium, 

cadmium, and fluoride were exceeded in 17 to 30 percent of 

the samples. No upgradient ground-water samples exceeded

7.302 1 82,194.5

4

34 +













 = − SO

δ S

Figure 10. Relation of the inverse of sulfate concentration to sulfur-isotope ratios for selected water samples 

from the Fleming abandoned mine site, Tuscarawas County, Ohio.

-20.0

-15.0

-10.0

-5.0

0.0

5.0

0 0.001 0.002 0.003 0.004 0.005

INVERSE OF SULFATE, LITER PER MILLIGRAMS

SULFUR-ISOTOPE RATIO, IN PER MIL

PFBC by-product Upgradient ground water

Downgradient ground water

Spring water

Application-area interstitial water

Control-area interstitial water
20 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

the standard for beryllium; however, 29 of 30 ground-water 

samples from downgradient of the site exceeded the MCL. 

Only one sample from the application-area interstitial water 

exceeded the MCL for beryllium. The MCL for cadmium 

was exceeded in 61 of 206 samples, but 20 to 40 percent of 

each water type (including upgradient ground water and 

control-area interstitial water) also exceeded this MCL. 

Therefore, the source of beryllium and cadmium is likely 

related to spoil and (or) the aquifer materials at the mine 

site. The MCL for fluoride was exceeded in almost half of 

the application-area interstitial-water samples but no other 

samples. The source of fluoride is likely from fluorite 

(CaF2), which is a common trace mineral associated with 

the dolomitic sorbent. The MCL for lead (0.015 mg/L) was 

exceeded in only one control-area interstitial water sample 

with a concentration of 0.058 mg/L. No water samples 

exceeded the MCLs for arsenic and selenium (as of February 2002, both MCLs were at 0.050 mg/L). The greatest

concentration of arsenic was detected in one sample of 

application-area interstitial water with a concentration of 

0.010 mg/L. This sample was obtained during sampling 

round 1 (June 1995). As is the case for many abandoned 

mine sites in Ohio, the secondary MCLs for aluminum, iron, 

manganese, pH, sulfate, and total dissolved solids were 

exceeded in 50 percent or more of the samples. 

Table 5. Comparison of Maximum Contaminant Levels for drinking water established by the U.S. Environmental

Protection Agency with analyses of all water samples obtained from the Fleming abandoned mine site,

Tuscarawas County, Ohio

[mg/L, milligrams per liter; na, not applicable; TDS, total dissolved solids; min, minimum; max, maximum;

MCL, Maximum Contaminant Level]

Constituent

Maximum

Contaminant

Level

(mg/L)

Detection 

limit(s)a

(mg/L)

Total

number

of

samples

Number of 

detections 

above 

detection limit 

(percent

given in 

parentheses)

Number of 

samples

that exceed 

MCL

(percent

given in 

parentheses)

Maximum 

value

(mg/L)

National Primary Drinking-Water Regulations

Antimony 0.006 0.106 160 8 (5) unknownb 0.16

Arsenic 0.05 0.001 - 0.002 185 37 (20) 0 (0) 0.010

Barium 2 0.001 160 160 (100) 0 (0) 0.075

Beryllium 0.004 0.0001 - 0.002 160 79 (49) 30 (19) 0.037

Cadmium 0.005 0.001 - 0.08 206 90 (44) 61 (30) 0.17

Chromium 0.1 0.002 - 0.1 206 118 (57) 0 (0) 0.026

Copper 1.3 0.002 - 0.05 206 66 (32) 0 (0) 0.31

Fluoride 4.0 0.1 - 1.0 216 105 (49) 36 (17) 15.0

Lead 0.015 0.001 - 0.01 196 9 (5) 1 (<1) 0.058

Mercury 0.002 0.0001 61 0 (0) 0 (0) na

Nitrate 10 0.01 - 0.05 163 34 (21) 0 (0) 4.4

Selenium 0.05 0.001 - 0.005 178 38 (21) 0 (0) 0.006

National Secondary Drinking-Water Regulations

Aluminum 0.2 0.015 - 0.045 206 188 (91) 104 (50) 29.6

Chloride 250 0.1 - 1.0 216 188 (87) 1 (<1) 261

Copper 1.0 0.002 - 0.05 206 73 (35) 0 (0) 0.31

Fluoride 2.0 0.1 - 1.0 216 124 (57) 0 (0) 0.015

Iron 0.3 0.010 228 219 (96) 164 (72) 920

Manganese 0.05 0.0016 228 228 (100) 224 (98) 150

pH 6.5-8.5 na 267 na 192 (72c

) min 3.2

max 7.9

Silver 0.10 0.003 - 0.046 206 183 (89) 0 (0) 0.063

Sulfate 250 0.11 216 216 (100) 212 (98) 13,500

TDS 500 computedd 164 na 157 (96) 20,850

Zinc 5 0.001 - 0.06 206 188 (91) 0 (0) 3.8

a

 Detection limits varied depending on which laboratory performed the analysis, the dilution ratio, and the sample 

matrix. b The MCL was below the detection limit.

c

 Seventy-two percent of the pH measurements were below the minimum accepted value of 6.5. No samples exceeded the 

maximum accepted value of 8.5. d Total dissolved solids is computed as the sum of all dissolved constituents.
GEOCHEMICAL MODELING 21

Except for fluoride, all exceedances of the primary 

and secondary MCLs are due to the influences of AMD, not 

the PFBC by-product. Additionally, out of all the MCLs that 

were exceeded, only fluoride and sulfate are found in higher 

concentrations in the application-area interstitial waters than 

in control-area waters. A key consideration to comparisons 

of this type is whether these waters will ever be used as 

drinking-water sources. Given extremely high iron and sulfate concentrations derived from AMD, it is not likely that 

ground water from the site will be used as a drinking-water 

source, even for domestic animals. With regards to grazing 

by domestic animals, uptake of trace elements by vegetation 

was evaluated by Stehouwer and others (1996), who found 

that, with the exception of chromium, concentrations of all 

other trace elements in plant tissues either decreased or 

showed no response to application of PFBC by-product 

in spoil. 

The nearest drinking-water supplies in the area are 

from domestic wells that derive water from the underlying 

Mississippian sandstones, which include the Blackhand 

Sandstone (locally referred to as the “Big Injun”) and the 

Berea Sandstone. The domestic wells are at least 0.5 mi 

downgradient from the Fleming site. The nearest publicsupply wells, which are screened in alluvial sands and gravels beneath Sugar Creek, are about 5 mi away and provide 

drinking water to the city of Dover.

GEOCHEMICAL MODELING

The ultimate fate and transport of elements derived from the 

PFBC by-product remains in question. The chemistry of 

interstitial water, ground water, and spring water from the 

site shows that interstitial-water samples contain leachate 

derived from the PFBC by-product and that the leachate 

chemistry has changed greatly during the 7 years of sampling; however, examination of the graphs presented in this 

report indicate that little, if any, effects of leachate derived 

from PFBC by-product can be found in ground water or 

spring water. An objective of this study was to determine the 

fate and mobility of elements derived from the PFBC byproduct in an abandoned mine setting. To address this issue, 

three hypotheses were examined to determine the fate of 

elements derived from the PFBC by-product: (1) the sampling schedule missed the highest concentrations of PFBC 

by-product leachate, (2) the mass of PFBC by-product 

applied at the site was so small that dilution by rainwater 

and the overwhelming influence of AMD obscured detection by the methods used in this study, and (3) elements 

derived from the PFBC by-product leachate have precipitated as secondary minerals in the unsaturated zone. Each of 

the hypotheses is addressed individually below.

Hypothesis 1. The sampling schedule missed the 

highest concentrations of PFBC by-product leachate.

Immediately after application, the first few rainfall events 

may have dissolved readily soluble compounds from the 

PFBC by-product so that the maximum concentration of 

elements was mobilized to ground water before monitoring 

began. Application of PFBC by-product was completed in 

October 1994; however, the first sampling round was not 

done until June 1995. Additionally, other than interstitialwater sampling round 3, which coincided with a snowmelt 

event in January 1996, all sampling rounds were done during periods of little or no precipitation at base-flow conditions. Application-area interstitial waters show the greatest 

concentrations of elements during interstitial-water sampling round 3; therefore, soluble minerals from the PFBC 

by-product may dissolve primarily during precipitation 

events. Greenhouse pot studies by Stehouwer and others 

(1996) show that the concentrations of many soluble elements decrease rapidly after the first few flushes of water.

This hypothesis is precluded by the relatively slow 

ground-water-flow rates at the Fleming site. According to 

the ground-water-flow model by Haefner (1998), estimated 

traveltimes for ground water to flow from upgradient 

recharge areas to downgradient springs were on the order of 

tens of years, well within the sampling period. The shortest 

ground-water traveltime of 227 days was computed for a 

hypothetical water particle released on the water table near 

well cluster 4 that discharged at a downgradient spring. All 

other particles had traveltimes that exceeded 227 days, and 

the first sampling round was done within this timeframe. 

Although the sampling schedule for interstitial waters may 

have missed the maximum concentrations of elements associated with precipitation events, ground-water-flow rates 

were slow enough to ensure that any leachate that reached 

ground water was sampled during the study period.

Hypothesis 2. The mass of PFBC by-product 

applied at the site was so small that dilution by rainwater and the overwhelming influence of AMD obscured 

detection by the methods used in this study. The PFBC 

by-product was applied at 125 tons per acre over a 7-acre 

area for a total weight of 875 tons. The application mass 

was determined by calculating the required volume of 

PFBC by-product to bring the spoil pH up to 7. This represents addition of more than 43 tons of sulfur, 157 tons of 

calcium, and 82 tons of magnesium over the 7-acre area. 

Nevertheless, this amount may not have been adequate to 

influence the ambient concentrations in ground water and 

allow determination of the contribution of PFBC by-product 

leachate by analysis of mixing diagrams. As can be seen 

from median concentrations of many constituents, upgradient ground waters at the site also had relatively high concentrations of dissolved constituents compared to ground-water 

samples collected in other areas of eastern Ohio (as reported 

in Sedam and Francy, 1993).

Graphs of water-quality characteristics indicated that 

several downgradient ground-water samples might have 

mixed with a small amount of PFBC by-product leachate 

(figs. 7, 8, and 9). To investigate this possibility further, 
22 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

water-quality data from rainwater, interstitial water, and 

ground water were modeled in NETPATH (Plummer and 

others, 1994). For this simulation, the observed chemical 

concentrations of selected water samples were combined to 

produce 12 possible models. Many models were eliminated 

on the basis of unrealistic output, such as the requirement 

for precipitation of pyrite. One reasonable model was identified as below:

Therefore, the observed chemistry of downgradient 

ground water may have been derived from mixing with a 

very small amount of the PFBC by-product. Other models 

do not require mixing with any PFBC by-product at all; so, 

the 1-percent estimate might be a maximum value, and dilution of the PFBC by-product leachate was likely.

Hypothesis 3. Elements derived from the PFBC 

by-product leachate have precipitated as secondary minerals in the unsaturated zone. High concentrations of dissolved solids derived from the PFBC by-product leachate 

may lead to precipitation of minerals including calcite 

(CaCO3), dolomite (CaMg(CaCO3)2), ettringite 

(Ca6Al2(SO4)3(OH)12.

26H20), and gypsum (CaSO4

.

2H2O) 

(Stehouwer and others, 1996). To evaluate whether thermodynamic conditions were favorable to precipitate secondary 

minerals, the geochemical model PHREEQC (Parkhurst and 

Appelo, 1999) was employed. PHREEQC uses chemical 

data from water-quality analyses to compute saturation indices for minerals. The saturation index (SI) is defined as the 

log of the ion activity product (IAP) divided by the solubility constant (K) for a given mineral.

SI = log IAP

 K . (4)

If SI is greater than zero, the mineral could precipitate but not dissolve; if SI is less than zero, the mineral 

could dissolve but not precipitate; and if SI is equal to zero, 

the mineral could be dissolving or precipitating. The primary assumption associated with these calculations is that 

all phases are in equilibrium—an assumption rarely met in 

natural environmental conditions. Nonetheless, this exercise 

is useful to evaluate the possibility that secondary minerals 

can precipitate or dissolve in the unsaturated zone and 

within aquifers beneath the Fleming site.

The SIs for all minerals given in the PHREEQC databases (phreeqc.dat and llnl.dat) initially were evaluated for 

each water sample with sufficient chemical data; however, 

only those minerals that are likely to exist in this 

environment or may be associated with the PFBC by-product are described below. In addition to the four minerals 

named above, gibbsite (Al(OH)3), ferrihydrite (Fe(OH)3), 

jarosite (KFe(SO4)2(OH)6), and melanterite (FeSO4

.

7H2O) 

were included because these minerals are common in AMD 

environments. Input data for PHREEQC included concentrations of dissolved major and trace elements in water, 

alkalinity, pH, water temperature, and pE. (pE is analogous 

to pH, except that pE is equal to the negative log of the 

activity of electrons. It is closely related to the reductionoxidation potential.) pE values for ground-water samples 

and spring-water samples were calculated from the Fe2+/

Fe3+ couple obtained from field measurements of ferrous 

and total iron (ferric iron was calculated as the difference 

between ferrous and total iron). 

Ferrous and total iron concentrations were not measured in the field in interstitial-water samples because of 

insufficient sample volumes. It was assumed that interstitial-water samples were in equilibrium with the atmosphere 

and were saturated with respect to dissolved oxygen. This 

assumption provided maximum possible pE values and is 

likely valid only for near-surface samples because oxygen is 

depleted with depth by processes such as decay of organic 

matter. Only redox-sensitive minerals (including ferrihydrite, jarosite, and melanterite) are affected by changing pE 

conditions. The influence of changing pE on SI for a sample 

of application-area interstitial water is shown in figure 11. 

The oxygen redox couple resulted in a calculated pE 

.

Figure 11. Relation of pE to saturation index calculated for 

selected minerals from an application-area interstitialwater sample collected at the Fleming abandoned mine 

site, Tuscarawas County, Ohio.

 26 percent rainwater

+ 1 percent PFBC by-product application-area 

interstitial water

+73 percent upgradient ground water

Downgradient ground water minus precipitation 

of jarosite (KFe3(SO4)2(OH)6)

-14

-12

-10

-8

-6

-4

-2

0

2

4

16.3 14.3 12.3 10.3 8.3 6.3

pE (Dimensionless)

SATURATION INDEX

(Dimensionless)

Ferrihydrite

Jarosite

Gypsum

Melanterite

EXPLANATION
GEOCHEMICAL MODELING 23

of 16.3, indicating extremely oxidizing conditions. PHREEQC was run six times with pE values ranging from 16.3 to 

6.3 while keeping all other water-quality characteristics 

constant. The approximate lower limit of pE value of 6.3 

was comparable to pE values calculated for anoxic (less 

than 0.1 mg/L of dissolved oxygen) ground-water samples. 

The SI for ferrihydrite and jarosite decrease with decreasing 

pE, whereas the SI for melanterite increases with decreasing 

pE (fig. 11). Although gypsum is the only pE-insensitive 

mineral shown in figure 11, the SIs calculated for calcite, 

dolomite, ettringite, and gibbsite also are insensitive to 

changing pE within the calculated pE range.

The distributions of SIs for the eight minerals listed 

above are given as boxplots in figures 12 and 13. Most water 

samples were supersaturated with respect to the hydroxides 

of aluminum (gibbsite) and iron (ferrihydrite). These 

hydroxides are relatively insoluble in oxidizing conditions 

and are known to adsorb trace elements. Therefore, the 

favorable conditions for hydroxide precipitation within the 

unsaturated zone may serve as a trace-element sink. All 

ground-water samples were anoxic, with median dissolvedoxygen concentrations of less than 0.1 mg/L; therefore, it is 

unlikely that minerals such as ferrihydrite or jarosite, which 

favor oxic conditions, could precipitate within pore spaces 

in aquifer materials. The resulting distribution of supersaturation with respect to ferrihydrite and jarosite in ground 

water likely is an artifact of the method in which pE was 

calculated. Ferrous and total iron concentrations of all 

ground-water samples were measured in the field to calculate pE values based on the Fe2+/Fe3+ redox couple. In an 

nsensitive to changing pE within the calculated pE range. 

anoxic environment, all iron should tend towards the 

reduced (Fe2+) form; however, field measurements indicated the presence of some oxidized iron (Fe3+) in almost 

all samples. Even a small amount of oxidized iron resulted 

in saturation with respect to ferrihydrite and jarosite. Dissolved oxygen may be at high enough concentrations at the 

capillary fringe to allow precipitation of these minerals, but 

fluctuating or rising water levels may once again cause dissolution. Although not given here, the SIs for goethite 

(αFeOOH) were similar to those for ferrihydrite (all samples except those from spring water had SIs greater than 

zero). The boxplots show that more samples of control-area 

interstitial waters were undersaturated with respect to ferrihydrite than those for the application area. This is likely the 

result of higher pH in the application area caused by the 

neutralizing effect of the PFBC by-product leachate. More 

ground-water samples have SIs greater than zero with 

respect to jarosite than for any other water types. All water 

samples were undersaturated with respect to melanterite. 

Very few water samples were supersaturated with 

respect to calcite and dolomite. Those samples with SI 

greater than zero were from the PFBC by-product application-area interstitial waters. Boxplots for ettringite had a 

similar distribution to gibbsite, although the values of SIs 

for ettringite were much lower. The SI values for ettringite 

for all water samples were well below zero because ettringite precipitation generally requires pH conditions above 

10.7 (Myneni and others, 1998). The similarities between 

the behavior of ettringite and gibbsite are most likely due to 

controls exerted on mineral precipitation by aluminum solubility. Several application-area interstitial water samples and 

upgradient ground-water samples had SIs for gypsum that 

exceeded zero.

These calculations indicate that precipitation of gibbsite, ferrihydrite, jarosite, calcite, dolomite, and gypsum 

may be occurring in the unsaturated zone and within aquifer 

materials at the Fleming site. 

Of the three hypotheses given above, dilution 

(hypothesis 2) is the most probable cause of the few detections of elements related to the PBFC by-product in downgradient ground waters. The small volume of PFBC byproduct was virtually insignificant when compared to the 

overwhelming effects of AMD. It is likely that leachate 

from the PFBC by-product has mixed with downgradient 

ground water, but the chemical- and isotopic-detection 

methods used in this study may have been inadequate to 

resolve the relatively small amounts of leachate from the 

ambient ground water. In addition to dilution, precipitation 

of secondary minerals (hypothesis 3) in the unsaturated 

zone may have reduced the concentrations of major and 

trace elements in water. Consequently, it is improbable that 

any of the toxic elements of concern (arsenic, lead, or selenium) will cause water-quality problems at this site or other 

sites where similar application rates are used. It should be 

noted that if these elements were precipitated within or 

adsorbed by secondary minerals, they could potentially 

remobilize after recharge events or if geochemical conditions within the unsaturated zone or aquifers change from 

current conditions.
24 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

Figure 12. Distribution of saturation indices for gibbsite, ferrihydrite, jarosite, and melanterite for selected water samples 

from the Fleming abandoned mine site, Tuscarawas County, Ohio.

6

4

2

0

-2

-4

-6

-8

5

0

-5

-10

-15

-20

15

10

5

0

-5

-10

-15

x

o

x

x

GIBBSITE (Al(OH)3)

AI CI UG DG SW

SATURATION INDEX

AI CI UG DG SW

MELANTERITE (FeSO4

. JAROSITE (KFe 7H2O) 3(SO4)2(OH)6)

Saturated

Undersaturated

EXPLANATION

75th percentile

Median

25th percentile

Outside value 1.5 to 3 times

the interquartile range

Far-out value greater than 3 times

the interquartile range

AI

CI

UG

DG

SW

Application-area interstitial water

Control-area interstitial water

Upgradient ground water

Downgradient ground water

o Spring water

x

6

5

4

3

2

1

o

x

o

7 8

FERRIHYDRITE (Fe(OH)3)

x

o

xx

x

o

o

x

o

x

o

x

o

x

x

x

x

x
GEOCHEMICAL MODELING 25

Figure 13. Distribution of saturation indices for calcite, dolomite, ettringite, and gypsum for selected water samples from 

the Fleming abandoned mine site, Tuscarawas County, Ohio.

x

o

o

x

o

o

x

o

o

o

x

o

o

1

0

-1

-2

-3

-4

-5

-6

-7

2

0

-2

-4

-6

-8

-10

-12

-14

-15

-20

-25

-30

-35

-40

-45

-50

6

4

2

0

-2

-4

CALCITE (CaCO3) DOLOMITE (CaMg(CO3)2)

AI CI UG DG SW

SATURATION INDEX

AI CI UG DG SW

GYPSUM (CaSO4

. ETTRINGITE (Ca6Al2(SO4)3(OH)12 2H2O) .26H2O)

x

o

x

o

x

Saturated

Undersaturated

EXPLANATION

75th percentile

Median

25th percentile

Outside value 1.5 to 3 times

the interquartile range

Far-out value greater than 3 times

the interquartile range

AI

CI

UG

DG

SW

Application-area interstitial water

Control-area interstitial water

Upgradient ground water

Downgradient ground water

o Spring water

x

-55
26 Water quality and geochemical modeling of water at an abandoned coal mine reclaimed with coal combustion by-products

SUMMARY AND CONCLUSIONS

A 7-acre abandoned mine site (the Fleming site) in eastern 

Ohio was reclaimed with 125 tons per acre of pressurized 

fluidized bed combustion (PFBC) by-product and 50 tons 

per acre of yard-waste compost. The hydrology and water 

quality at the site was studied over a 7-year period to determine the environmental effects of reclamation with this 

material. The two main processes of interest in this study 

were (1) dissolution and leaching of PFBC by-products 

applied to the surface of the study area, and (2) the generation of acid mine drainage (AMD) in spoil left at the surface 

of the site after mining ceased. Addition of alkaline PFBC 

by-product was intended to increase pH, thereby reducing 

the solubility of major and trace elements in water. This 

report summarizes water-quality data from the study and 

presents several hypotheses regarding the fate of elements 

derived from the PFBC by-product. 

Water quality in application-area interstitial waters 

(samples collected from the unsaturated zone) clearly 

showed the influence of leachate derived from the PFBC byproduct. Application-area interstitial waters had elevated pH 

and specific conductance along with higher concentrations 

of boron, calcium, chloride, fluoride, magnesium, potassium, strontium, and sulfate than water samples collected in 

a control area where the PFBC by-product and compost 

were not used. Of these elements, only boron presents a 

potential concern because boron is known to be phytotoxic 

at high concentrations, and one of the goals of abandoned 

mine reclamation is reestablishment of vegetation. Sulfurisotope ratios also showed the influence of PFBC by-product leachate because sulfate derived from the PFBC byproduct had relatively positive isotope ratios as compared to 

those for spoil and aquifer materials. Increases in pH reduce 

the solubility of some elements; therefore, the median concentrations from application-area interstitial waters were 

lower for iron, nickel, and zinc than those in the control 

area. Graphical techniques used to highlight water-quality 

differences were successful with Fleming-site waters 

because the coal and sorbent used in the PFBC process were 

from different formations than those at the Fleming site and 

therefore had different geochemical signatures.

Comparisons of water-quality data obtained at the 

Fleming site to the U.S. Environmental Protection Agency 

Maximum Contaminant Levels (MCLs) show many exceedances of the MCLs. Out of all the MCLs that were 

exceeded, only fluoride and sulfate were found in higher 

concentrations in the application-area interstitial waters than 

in control-area waters. There were no exceedances of MCLs 

for elements of concern such as arsenic, lead, or selenium. It 

is not likely that the water at the Fleming site will ever be 

used as a drinking-water source.

Three plausible hypotheses were developed to investigate the fate and transport of elements derived from the 

PFBC by-product and the apparently minor influence of the 

by-product on water quality: (1) the sampling schedule 

missed the highest concentrations of PFBC by-product 

leachate, (2) the mass of PFBC by-product applied at the 

site was so small that dilution by rainwater and the overwhelming influence of AMD obscured detection by the 

methods used in this study, and (3) elements derived from 

the PFBC by-product leachate have precipitated as secondary minerals in the unsaturated zone. Graphical analysis of 

median concentrations of elements associated with the 

PFBC by-product show that the concentrations of elements 

seemed to have peaked at or around the time of interstitialwater sampling round 3 (January 1996, 15 months after reclamation); therefore, changes in water quality (if any) 

should have been detected during this timeframe. Results 

from the geochemical models NETPATH and PHREEQC 

indicate that downgradient ground water may have mixed 

with a small amount of PFBC leachate and that thermodynamic conditions are favorable for secondary minerals to 

precipitate in the unsaturated zone and in aquifers at the site. 

Because the amount of PFBC by-product was small compared to the mass of other elements already in solution at 

the site, it is likely that dilution caused difficulty in distinguishing constituents from the PFBC by-product in downgradient ground waters.

Reclamation of the site was successful in that vegetation was reestablished and erosion was reduced. It was also 

successful in the sense that water quality in the PFBC byproduct application area shows a raised pH, which was 

maintained throughout the 7-year period after reclamation. 

Because of low application rates and sorption onto iron and 

aluminum hydroxides, it is improbable that any of the toxic 

elements of concern (arsenic, lead, or selenium) will cause 

water-quality problems at this site or other sites where similar application rates are used. At the onset of this project, 

researchers from the U.S. Geological Survey and the Ohio 

Agricultural Research and Development Center anticipated 

ground-water-quality improvement as a result of reclamation and soil amendment with PFBC by-products. Seven 

years later, however, ground-water quality remained poor 

and showed no signs of improvement during the 

study period. 

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