1988-04-11_PERMIT FILE - C1981008A (23)

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However, Peabody has developed plans for sampling overburden during mining to identify the quantity and quality of deleterious material (see Tab 6, Geology). Naturally occurring waters in the surrounding undisturbed ground water system exhibit a high degree of mineralization (see Tab 7, Hydrologic Description). Well yields from these units are low, and most recharge to the local undisturbed ground water system is from both the Lower Second Park and the west lateral irrigation ditches and associated laterals via seepage. This localized, artificial source of ground water recharge will augment slower, natural recharge contributions during the spoil resaturation process. As spoil resaturation progresses, the quality of ground water in the spoil will likely approach the water quality of surrounding units. Mixing and the overall high degree of neutralization potential of the spoil material will minimize changes in ground water quality. Based on physical and chemical analyses performed on core samples taken from the lithologic units to be affected by mining (see Tab 6, Geology), a classification system has been developed for these units with regard to handling during operation and reclamation activities. A handling plan for those material classes identified by sampling as being potentially deleterious to revegetation or the ground water quality in either mining area has been developed and is presented in Tab 21, Mine Soil Reconstruction. It is not anticipated that Peabody will transfer ownership and use of any wells completed within either the Nucla Mine or Nucla East mining areas. Bore holes, shafts, wells, and auger holes will be cased and/or sealed to prevent possible ground water degredation from mixing of waters of different quality within the bore holes and acid or toxic surface runoff entering the bore holes. A specific plan for sealing of bore holes, exploration holes, auger holes, wells, and shafts is presented in Tab 18, Hydrologic Reclamation Plan. Ground Water Quantity. Typical backfilling methods largely involve the use of dozers and scrapers (see Tab 20, Backfilling and Grading). Studies by Rahn (1976) and VanVoast and Hedges (1975) indicate that replaced spoil materials exhibit greater porosities and hydraulic conductivities because of increased void values, regardless of how the spoil material is replaced in the pits. Spoil replacement (backfilling) using methods outlined in Tab 20 (Backfilling and Grading) will ensure the eventual resaturation of the disturbed areas (pits), minimizing the adverse effects of mining on ground water flow. 16-2 Revised 04/11/88