Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields.At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and delta(15)N and delta(18)O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human health.Fecal streptococcus bacteria were detected at least once in groundwater from all monitoring wells at both sites. Fecal streptococcus was more common and at greater concentrations than fecal coliform. The microbiological data suggest that filtration of bacteria by soils may not be as effective as commonly assumed. The presence of fecal bacteria in the shallow groundwater may pose a significant threat to human health if the ground water is used for drinking. Both facilities are less than 4 years old and the short-term impacts of these manure storage facilities on groundwater quality have been limited. Continued monitoring of these facilities will determine if they have a long-term impact on groundwater resources. (C) 2002 Elsevier Science Ltd. All rights reserved.

The preparation and combustion of high sulfur coal generates many waste products including cleaning and combustion wastes. Pyrite is associated with coal cleaning wastes and it makes them potentially acidic. Coal slurry solids (CSS), the finest textured cleaning wastes, are stored in large impoundments. After the impoundments are retired, they must be reclaimed with a 1.2 in soil cap. Reclamation of abandoned CSS impoundments by direct revegetation would avoid costs associated with the required soil cap. However, CSS have physical and chemical limitations for plant growth including undesirable pH, surface temperatures, and moisture holding capacity. Fluidized bed combustion is a coal combustion technique designed to reduce smoke stack emissions of SO{sub 2}. It results in a highly alkaline by-product (FBC). The combination of CSS and FBC may allow direct revegetation of CSS materials. This would possibly be a more cost effective method of reclaiming CSS materials than using a soil cap while creating an economic value for FBC by-products. This will also preclude the necessity of disturbing a borrow area for the soil cap. An experiment was designed to evaluate the potential for CSS/FBC mixtures to support direct revegetation. Three test blocks with 18 plots each were established on amore » temporarily inactive portion of an active coal slurry impoundment. The addition of FBC increased the pH of the potentially acidic CSS. Soil fertility analyses indicated Al, B, Ca, Mg, Zn, and soluble salts increased with additions of FBC, while Cu, Fe, K, P, and S remained relatively unchanged, and Mn and Na concentration decreased. Direct revegetation of CSS materials may be facilitated by the addition of FBC by-products. However, other treatments in addition to FBC amendments may be necessary to optimize conditions for plant growth.« less

The highly alkaline residue from the fluidized-bed combustion (FBC) of coal may be an environmentally acceptable material for use in neutralizing acid produced by the oxidation of pyrite in coal slurry solids (CSS). Previous research indicated that FBC residues in mixtures with pyrite-rich CSS neutralized the acid produced by or attenuated the oxidation of pyrite in CSS. In the present research we intend to collect cores of unconsolidation material and sample pore gases from a reclaimed coal slurry impoundment. The data gathered will provide background information necessary for the development of a predictive computer model of the generation and migration of acid in a reclaimed coal slurry impoundment. The conceptual model for the oxidation of pyrite at near-neutral conditions has been revised. The model is being built around the method of Morel and Hering (1993) and Westall (1986).

The highly alkaline residue from the fluidized-bed combustion (FBC) of coal may be an environmentally acceptable material for use in neutralizing acid produced by the oxidation of pyrite in coal slurry solids (CSS). Previous research indicated that FBC residues in mixtures with pyrite-rich CSS neutralized the acid produced by or attenuated the oxidation of pyrite in CSS. The intent in this research was to collect cores of unconsolidated material and sample pore gases from a reclaimed coal slurry impoundment. The gas composition data would provide background data for the development of a predictive computer model of the generation and migration of acid in a reclaimed coal slurry impoundment. Cores of coal slurry were collected on May 16--18, 1994 from four holes in a reclaimed coal slurry impoundment. There was no unsaturated zone in the coal, so no gas samples can be collected from that zone. The authors installed three samplers in one hole. Two of the samplers are in the saturated zone (in the coal) and the third one might be in the unsaturated zone, but in the soil cover above the coal particles. They plan to collect samples in about mid-June. The water and solids from the cores are being separated for chemical analysis. The computer model for the oxidation of pyrite at near-neutral conditions is being developed. The first portion of code, the calculation of thermodynamic equilibrium without consideration of ionic strength, has been written. The methods of Morel and Hering (1993) and Westall (1986) are the basis for the model, however, the model does not follow the matrix solution used by them. Rather, an algebraic solution is used. A matrix similar to the one reported last quarter was used to formulate mass balance and material balance equations.

Three tasks are being conducted in this research project. All are related to understanding the chemistry and mineralogy of the co- disposal of fluidized bed combustion (FBC) wastes with coal slurry solid (CSS) from a coal preparation plant. During coal cleaning, pyrite and other heavy minerals and rock materials are rejected from the coal and discharged in an aqueous slurry to an impoundment. Soluble components and acid-base reaction products from mixtures of fluidized bed combustion (FBC) wastes and coal slurry solids (CSS) are being extracted in aqueous solution in a series of batch experiments. These experiments are being conducted in order to provide information on the solution chemistry associated with the mixtures over an extended time. Large volumes of extracts from three mixtures of FBC waste and CSS are being prepared for use in experiments to ascertain the adsorption/desorption reactions that occur between components of the extracts and three commonly occurring Illinois soils. A computer program that simulates the effects of pyrite oxidation and acid neutralization in a spoil heap is being corrected and improved.

Three tasks are being conducted in this research project, all related to understanding the chemistry and mineralogy of the co-disposal of fluidized bed combustion (FBC) wastes with coal slurry solid (CSS) from a coal preparation plant. During coal cleaning, pyrite, other heavy minerals, and rock materials are rejected from the coal and discharged in an aqueous slurry to a slurry pond. After dewatering and abandonment of the pond, the pyrite may oxidize and produce acid that may migrate into the underlying groundwater system. If an alkaline product, such as FBC waste, is mixed with the CSS, then the acid will be effectively neutralized as it is produced. In Task 1, soluble components and acid-base reaction products from mixtures of FBC waste and CSS are being extracted for up to 180 days in a series of aqueous batch experiments. The final two sets of extractions, 90- and 180-days, were completed. The extracts and solids from these experiments were submitted for analysis of cations, anions, and mineralogy. In Task 2, 10 L of extracts from three mixtures of FBC waste and CSS were prepared for use in experiments to determine the adsorption/desorption reactions that occur between components of the extracts and three commonly occurring Illinois soils.

The effect of Cl complexation in extracts of a flue gas-scrubber incinerator fly ash sample on the sorption of Cd and Pb by kaolinite and illite was investigated using batch-sorption methods. In the pH range of 5 to 9, Cl complexation may reduce sorption and thus increase the mobility of these metals. When an ash-water suspension was acidified to pH 6.85, the dissolution of Cl and Ca essentially eliminated Cd sorption because of complexation and cationic competition. Cadmium would be considered as either mobile or very mobile under these conditions. Lead was not soluble in the pH-6.85 suspension. At pH 12, the approximate pH of water in contact with flue gas-scrubber fly ash, Cd was essentially insoluble and Pb occurred as anionic Pb hydroxide. Anionic Pb was sorbed by the two clays, and the extent of sorption was not influenced by Cl or carbonate complexation. Sorption constants, derived from isotherms, suggested that Pb would be relatively immobile in saturated soil-water systems. The recent concern that highly alkaline, flue gas-scrubber fly ash may release environmentally significant concentrations of mobile Pb when placed in an ash-disposal site with a soil liner should be reevaluated in light of this study.

The highly alkaline residue from the fluidized-bed combustion (FBC) of coal may be an environmentally acceptable material for use in neutralizing acid produced by the oxidation of pyrite in coal. slurry solids (CSS). Previous research indicated that FBC residues in mixtures with pyrite-rich CSS neutralized the acid produced by or attenuated the oxidation of pyrite in CSS. In the present research project we retrieved five drill cores from a reclaimed coal slurry impoundment, and installed three samplers in one of the core holes. The solids were chemically and mineralogically analyzed. Display of the mineralogical data on a cross section showed that pyrite was randomly distributed through much of the length of the coal slurry impoundment. Trace concentrations of heavy metals were correlated with pyrite in the core solids. Water samples were collected and analyzed. The water analyses showed that nutrients are insufficient to support plant growth without supplemental fertilization. The analytical data will provide background information necessary for the development of a predictive computer model of the kinetics of pyrite oxidation at near-neutral pH conditions. Programming of a computerized model to simulate pyrite oxidation under near-neutral pH conditions was begun. The program includes ideas from Morel and Hering (1993) and species are calculated in terms of 7 components of known concentrations. The ionic strength of the solution, the species activity coefficients, and the activities are calculated iteratively.

The three tasks conducted in this research project were related to understanding the geochemistry and mineralogy of the co-disposal of fluidized bed combustion (FBC) wastes with coal slurry solid (CSS) from a coal preparation plant. During coal cleaning, pyrite, other heavy minerals and rock fragments are separated from the coal and discharged in an aqueous slurry to an impoundment. After dewatering and closure of the impoundment, the pyrite can oxidize and produce acid that can migrate into the underlying groundwater system. The addition of FBC residue to the CSS will buffer the pore water pH to approximately 7.8. In Task 1, soluble components and acid-base react ion products from mixtures of FBC waste and CSS were extracted for 3 to 180 days in aqueous batch experiments. The results of these extractions showed that, eventually, the extracts would attain a pH between 7 and 8. That pH range is characteristic of an aqueous system in equilibrium with calcite, gypsum, and atmospheric carbon dioxide. After 180 days, the mean calcium concentration in all of the extracts was 566{+-}18 mg/L and sulfate concentrations averaged 2420{+-}70 mg/L. In Task 2, three extracts from CSS/FBC residue mixtures were prepared for use in experiments to determine the adsorption/desorption reactions that occur between solutes in the extracts and two common Illinois soils. Time constraints allowed the use of only two of the extracts for adsorption studies. The concentrations of most solutes were not significantly lowered by adsorption at the pH of the extract-soil suspension, nor over a wide range of pH. The results suggest that the type of solutes that were released by the CSS/FBC residue mixture would not be attenuated by adsorption. In a modified Task 3, the literature on the kinetics of pyrite oxidation in near-neutral to alkaline pH was reviewed in preparation for future development of a computer model of pyrite oxidation in CSS/FBC residue codisposal.

Fluidized bed combustion (FBC) is a relatively new technology that is used commercially for the combustion of coal. In Illinois, this technology is valuable because it allows the combustion of Illinois high sulfur coal without pollution of the atmosphere with vast quantities of sulfur oxides. In FBC, coal is mixed with limestone or dolomite either before injection into the combustion chamber or in the combustion chamber. As the coal burns, sulfur in the coal is oxidized to S0{sub 2} and this is trapped by reaction with the limestone or dolomite to form gypsum (CaSO{sub 4} {center_dot} 2H{sub 2}O). Solid by-products from FBC are generally a mixture of calcium oxide, gypsum, coal ash, and unburned coal. The present research project is designed to provide initial data on one possible use of FBC waste. FBC wastes from five different locations in Illinois are mixed with coal slurry solids (CSS) from two different coal preparation plants at Illinois coal mines. In mixtures of FBC waste and coal slurry solids, the alkaline components of the FBC waste are expected to react with acid produced by the oxidation of pyrite in the coal slurry solid. An objective of this research is to determine the chemical composition of aqueous leachates from mixtures of FBC wastes, generated under various operating conditions, and the coal slurry solids. These data will be used in future research into the ability of such mixtures to support seed germination and plant growth. The final goal of this and future research is to determine whether mixed FBC waste and coal slurry solids can be used as a satisfactory growing medium in slurry pond reclamation. The chemical analyses of the 8 starting solids (5 FBC wastes, 2 Css samples, and 1 agricultural limestone sample) were completed.

The present research project is designed to provide initial data on one possible use of FBC waste. FBC wastes from five different locations in Illinois are mixed with coal slurry solids (CSS) from two different coal preparation plants at Illinois coal mines. In mixtures of FBC waste and coal slurry solids, the alkaline components of the FBC waste are expected to react with acid produced by the oxidation of pyrite in the coal slurry solid. An objective of this research is to determine the chemical composition of aqueous leachates from mixtures of FBC wastes, generated under various operating conditions, and the coal slurry solids.

Two liquid hazardous wastes, an alkaline brinelike solution and a dilute acidic waste, were mixed with finely ground «250 jlm) rock samples of three injection-related lithologies, sandstone, dolomite, and siltstone. The batch experiments were conducted for 155 to 230 days at 325°K and 10.8 MPa pressure. The pH and inorganic chemical composition of the alkaline waste were not significantly altered after 230 days of mixing. The acidic waste was neutralized by carbonate dissolution and transformed into a nonhazardous waste. Mixing the alkaline waste with the solid phases yielded several reaction products: brucite (Mg(OH)2)' calcite (CaC03), and possibly a sodium metasilicate. Claylike minerals formed in the sandstone; trace levels of hydrotalcite (M96AI2C03(OHh6'4H20) may have formed in the siltstone. Mixing the alkaline waste with a synthetic brine yielded brucite, calcite, and whewellite (CaC20 4·H20). The thermodynamic model PHROPITZ predicted that brucite and calcite would precipitate from solution in the dolomite and siltstone mixtures and in the alkaline waste-brine system. After 155 days of solid-liquid contact, the dilute acidic waste had not significantly altered the mineralogical composition of any of the three rock types. The model PHREEOE indicated that calcite was thermodynamically stable in the dolomite and siltstone mixtures, and it was detected in small quantities in the aged-solid samples. The sandstone-waste system appeared to equilibrate with amorphous silica, whereas silica equilibria may not have been attained in the dolomite and siltstone systems. Computer models like PHROPITZ and PHREEOE may be useful tools for estimating mineral equilibria in deep-well scenarios, but there is a need to expand the database used in these kinds of calculations. The predicted equilibria must be interpreted with caution. ACKNOWLEDGMENTS Partial support of this project was provided by the Hazardous Waste Research and Information Center of Illinois, a division of the Illinois Department of Energy and Natural Resources (ENR). Jacqueline M. Peden was the project officer of ENR Grant No. HWR 88066. We thank Randy Bergonson of the Cabot Corporation, Tuscola, Illinois, for providing the acidic waste sample. At the Illinois State Geological Survey, Keith M. Mitchell provided valuable technical aSSistance, Dr. Randall E. Hughes performed the essential mineralogical analyses, and Dr. Jonathan H. Goodwin contributed helpful discussions on zeolites.