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Matthew S. Hayes <br />June 28, 1989 <br />Page 13 <br />WECC commits to providing appropriate seal designs for the F seam and the B <br />seam as an appropriate time before sealing occurs. These seal designs will take <br />~ ~~ into account the actual conditions for the particular areas for both quality and <br />quantity of water, if present. Mine Safety and Health Administration (MSHA) <br />~rJ requirements will be adhered to as well. <br />B Seam Slopes and Ventilation Shaft <br />Hydrologic information presented in this technical revision application as well as <br />in the Mt. Gunnison Mining and Reclamation Plans shows that a unit downward <br />gradient exists in the Mesaverde formation in the mine block. Hydrologic data <br />also show that there are no aquifers present in the minable formation in the <br />Mt. Gunnison mine block. Permeabilities of the strata in the Mesaverde aze low <br />and quantity of water contained in the formation is small and localized. Quality <br />of water is generally not of a usable nature for drinking or livestock. <br />The above data and information leads to the following conclusions with respect <br />to the mine block hydrology and multiple seam mining: <br />1. Since unit downward gradient exists, mining will not change the <br />overall hydrologic regime in the mine block i.e. water is moving <br />generally downwazd and will continue to do so after mining ceases. <br />2. Mining will not change the chemical properties of the water <br />significantly since it already moves generally downwazd in the <br />formation. <br />3. Mined out rubblized zones will be more permeable than <br />existing coal seams and neazby strata. However unit downward <br />movement will not be altered by mining. <br />Therefore, WECC does not believe that the B, E and F seams will become <br />hydrologically continuous causing an increase in head in the F seam or cause <br />hydrochemical exchanges. Appropriate seal designs will be submitted prior to <br />the final sealing of the mine, taking into account the actual hydrologic conditions <br />of the mine, including the mined azeas is the lower seams and the slopes and <br />ventilation shaft. <br />