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The proposed sedimentation pond has been designed and will be <br />constructed and maintained to effectively trap sediment from run- <br />• off resulting from a 10-year, 24-hour precipitation event. <br />Drainage from the mining facility area, after treatment in the <br />sedimentation pond, is not anticipated to exceed effluent limita- <br />tions of any federal or Colorado agency requirements. Baseline <br />groundwater quality is discussed in Section 2.04.7. No water is <br />anticipated to be discharged from the underground mine. Like- <br />wise, no acid mine drainage of pH equal to or less that 6.0 is <br />expected. To date, no water has ever been discharged from the <br />old workings of the abandoned Edwards Mine. <br />Historically, the Bear Coal Company has experienced no pH prob- <br />lems with water discharging sampled in the vicinity of the opera- <br />tions. As reported in Section 2.04.7, all pH values of water <br />samples taken in the vicinity of the Bear Coal Company operations <br />have ranged between 6.0 and 9.0; therefore, it is anticipated <br />that no acid drainage will occur as the operations move westward <br />into the block of coal in Section 17. <br />4.05.3 Diversions and Conveyance of Overland Flow and Shallow <br />Groundwater Flow. and Ephemeral Streams Draining a_ <br />Watershed Less Than One Square Mile <br />The drainage and sediment control plan contained in Exhibit 11 <br />does not provide for diversion of surface drainage around the <br />• disturbed area. <br />• 4.05-3R <br />Revised June 29, 1990 <br />