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G. STATEMENT OF HYDROLOGIC CONSEQUENCES OF MINING <br />1. Increased Sediment Yields From Disturbed Areas <br />The current actual surface disturbed area of the mine is 28.6 <br />acres. Of this amount, 24.2 acres has been disturbed by previous <br />mining and is currently void of vegetation and topsoil. There are <br />steep slopes of uncompacted fill and spoil material which currently <br />have no sediment control. Gully erosion has taken place. <br />When available, water quality samples taken upstream and <br />downstream from the mine site should determine the effects of the <br />existing site on sediment yields. <br />The sediment control measures to be employed by the proposed <br />mine should significantly improve the existing site. These measures <br />• include the following: <br />1) construct a sediment pond to collect runoff from the entire <br />disturbed area, except for parts of the haul road, and <br />provide 24 hour detention time for all rainfall events less <br />than 10-year, 24-hour frequency. <br />2) dig up, regrade and compact the existing spoil piles with <br />new coal waste according to design specifications that call <br />for shallow slopes, terraces and ditches. <br />3) divert the entire undisturbed portion of the Starkville <br />Gulch drainage away from the mine site. This diversion <br />will be constructed according to specification presented <br />in Section 2.05.3(4) of this application to minimize <br />erosion. <br />4) Ditches along the haul road which do not drain into the <br />sediment pond will be provided with sediment stop <br />structures such as hay bales. <br /> <br />555 Revised - 04/13/90 <br />