Surface Coal Mining Effects on Ground Water Recharge (1990) / Chapter Skim
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Appendix D: Water Quality Issues Associated with Surface Coal Mining
Appendix D: Water Quality Issues Associated with Surface Coal Mining
Pages 141-155
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From page 141... ...
This appendix reviews criteria used to evaluate ground water quality; describes factors affecting the chemical composition of waters infiltrating unconsolidated overburden; surveys the methods for assessing and monitoring water quality; and investigates issues concerning water quality protection in surface coal mined areas.
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From page 142... ...
Water quality standards are established by the U.S. Environmental Protection Agency; the Office of Surface Mining Reclamation and Enforcement is responsible for enforcing these standards relative to coal surface mining activity.
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From page 143... ...
Carbonate and bicarbonate Trace metals: Iron Manganese Arsenic Mercur r Boron Lead Zinc Silver Copper Chromium Calcium Magnesium Sodium Potassium Chloride Aluminum Selenium Fluoride Radium-226 Nitrogen species Nitrate Ammonia Organic nitrogen Total suspended solids (TSSs) (surface water only)
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From page 144... ...
Common sulfide minerals associated with coal surface mining overburden are pyrite and marcasite. In the presence of oxygen introduced into the overburden during the mining process, these minerals will slowly oxidize: FeS2 + 7/2 O2 + H2O (chemical)
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From page 145... ...
, a familiar problem in the Appalachian region of the United States; however, these reactions also play a major role in the salinity problem associated with western coal surface mining. If unabated by deliberate control or by natural buffering reactions, the acid can become concentrated enough to solubilize deleterious trace metals, such as aluminum, arsenic, zinc, copper, and selenium.
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From page 146... ...
Cation Exchange and Adsorption Clay minerals, precipitated iron hydroxides, amorphous silicic acids, and organic matter are all capable of sorbing cations from solution and releasing equivalent amounts of other cations into solution. The mechanism of cation exchange is based on the metal-binding properties of negatively charged hydroxyl groups on clays, metal precipitates, and organic substances.
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From page 147... ...
This is of great importance in ground water quality monitoring, especially, for example, to assess offsite effects of surface mining. As contaminated ground water moves laterally through an aquifer, an offsite monitoring well will first show the arrival of sulfate, chloride, and other nonsorbing chemicals.
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From page 148... ...
Biogeochemical processing of nitrogen species in coal spoils has been demonstrated (Williams, 1975~. Onsite Disposal of Wastes Fly ash, scrubber sludges, wastes from coal cleaning, spent machine oils, municipal waste, and industrial waste have been buried in the backfill of surface coal mines (NRC, 1981a)
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From page 149... ...
Pre-mining water samples are evaluated to obtain baseline data for mine permits. Samples collected during and after mining are used to evaluate water quality as a result of mining activities.
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From page 150... ...
however, were found to more closely approximate field conditions, and data generated from such tests are useful in identifying potentially toxic strata and formulating overburden-handling plans to dispose of problem spoils (Perry, 1985; Caruccio and Geidel, 1986~. Although still limited in use, computer models are gaining popularity as a method to simulate ground water quality as a result of coal surface mining (Western Water Consultants, Inc., 1985;
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From page 151... ...
B.C. Perform whole Quick and easy Does not provide Bruynesteyn and research rock analysis; test with low rate data; Duncan, 1979; test relate acid cost.
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From page 152... ...
B.C. Place pulverized Similar to To date data Bruynesteyn and research sample in beaker beaker leach from this test Duncan, 1979; test with with water and test; oxygen have not been Caruccio and bacteria bacteria and is not limited correlated to Geidel, 1986 agitate to and text any other incorporate incorporates test data.
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From page 153... ...
Software programs to evaluate the hydrologic impacts, including ground water quality of coal surface mining are available (Whitehouse et al., 1989; Rymer II et al., 19889. Computer modeling is expected to assist in providing information on a topic of considerable concern: What are the cumulative effects of multiple coal surface mines on the ground water quality of..a region, and how long is this impact expected to last?
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From page 154... ...
Re-mining to Control Water Quality Much of the current ground and surface water pollution in the Appalachian region is associated with abandoned coal mines. Re-mining of abandoned coal mines, which contain substantial mineable coal reserves, is a viable means of minimizing a significant water quality problem.
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From page 155... ...
As a result of pre-mining overburden assessment, there is some selective materials handling, blending of spoils, encapsulation of toxic and reactive spoils, special contouring, and controlled revegetation to minimize ground water contamination. These techniques at this time are "more art than science." Selective materials handling, blending, and isolation have been particularly practiced with sulfidic overburden, but greater consideration should be given to selective materials handling to avoid dissolution of soluble salts in western coal surface mining operations.
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