2012-01-05_REVISION - C1980005 (8)

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IV. Topsoil wells were placed, completed and monitored in such a manner so that the travel time and velocity predictions made can be verified. The Cow Camp alluvial well GW -S69 has been transferred to the Peabody Sage Creek permit. The Bond Creek well remains in the Seneca II groundwater monitoring plan, with the most recent reporting data submitted with the Annual Hydrology Report. Seneca Coal Company also performed an aquifer test at a well completed in the Fish Creek alluvium near the confluence of Bond and Fish Creeks. This test indicates that the Fish Creek alluvial aquifer is capable of storing and transmitting substantially more water than that of the sub - drainages. Slug injection tests indicated that the transmissivity of this aquifer is about 37.6 ft /day, while the K value was calculated to be 7.5 ft /day. Therefore, it is thought that the potential impacts to the baseline water quality of the Fish Creek alluvial aquifer, due to the poor quality inflows from tributary alluvial aquifers, will be mitigated by dilution. The Division has reviewed the 1987 -2010 Annual Hydrology Reports for the Seneca II Mine, and previous statements of probable hydrologic consequences compiled by Seneca Coal Company and the Division. Pursuant to Rule 2.07.6(2)(c), the assessment of the probable consequences of the proposed mining operation and the assessment of the probable cumulative impact of all anticipated mining in the area on the hydrologic balance, as required by Rule 2.05.6(3) have been made. The proposed operation has been found to prevent material damage to the hydrologic balance outside the permit area. Information regarding topsoil may be found in Volume 7, Tab 9 of the original permit application package. Information in the original findings document for Seneca II Mine (August 10, 1981) identified two concerns; heavy clay concentration in certain soil types and limited soil salvaging in steep slope areas. To mitigate the heavy clay concentration, Seneca Coal Company proposed stripping topsoil in single lifts to mix different soil orders and to dilute the heavy clay concentration. This salvaged topsoil was either taken directly to regraded spoils or to a topsoil stockpile. This practice promotes the natural regeneration of existing species. Seneca Coal Company was originally (1981) approved to return approximately 1.4 feet (15 -18 inches) of highly suitable topsoil to regraded areas. As addressed in the Wolf Creek Permit Revision and approved by the Division, the depth of topsoil replacement was reduced to approximately 12.2 inches. To verify compliance of this topsoil replacement depth, Seneca Coal Company committed to a final topsoil balance survey for the duration of mining. To verify compliance, Seneca Coal Company expanded the quality control program as addressed on pages 9 -40 and 9 -41 of the revised permit document with a commitment to conduct annual topsoil balance surveys. The Seneca 21