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P1r. Dan I•iathews Page Two I.1ay 27 , 1982 operation. Because of the nature of the area where the surface facilities will be located, construction of a large sedimentation pond according to the requirements in Rule 4.05.6(3)(a) are impractical because of the large aerial er.panse necessary to stay above the groundwater table. The construction of a deeper sedimentation pond would result in disturbance of the groundwater level associated with the IJorth Fork of the Gunnison River. The Bear Coal Company plans the following cor~trol measures to effect compliance with the effluent limitations required under the provisions of the Coal Regulations of the Colorado t4ined Land Reclamation Board and the PJational Pollutant Discharge Elimination System (NPDES) permit: • Construction of diversion ditches to channel water from the disturbed area to a sedimentation pond • Use of small dugout structures along diversion ditches to reduce water velocity and decrease sediment load • Gravel filter dams along diversion ditches • A sedimentation pond with baffles t.o channel flow and reduce short-circuiting • Use of flocculants, as necessary, during large precipitation events • Annual maintenance of all structures The location of the diversion structures to be used at the Bear No. 3 site are shown on the Drainage and Sediment Control Plan if~ap (1~1ap S-1). These stn-uctur-es have been designed to handle the runoff fr-om a 10-year 24-hour pr°ecipitation event. All performance standards as set forth in Rule 4.05.3 in the bear Coal Company permit application for diversion ditches mill be applicable to the diversion ditches shown on the Drainage and Sediment Control Plan I'~ap (I•tap S-1). The design calculations for the diversion structures are attached to This letter. As shown on the Typical Filter Dani/Dugout Pond Design I~1ap (htap S-2), several small dugout ponds will be used in conjunction with gravel filter dams. The purpose of these structures is to reduce the velocity of water and to decrease sediment load of the water prior to reaching the sedimentation pond. The design calculations for the dugout ponds and gravel filter dams are attached. ~J°~~~~~I~ A ~r fii tNG. 71::,`~