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12-1999 THU 07:46 RM NEST ELK MINE FAX N0. 19709295015 P. 02 <br />.~ <br />li:chnicul Revision rL~. R6 Pine 2 <br />~l~~gu.sr 11, 1999 <br />As ststcd previously, a revised SL'DCAD model for the Shaft i!3 SAE has been included with this <br />response letter. This revised SAE model is also intended to comply with the abatement step <br />associated with NOV CV-99-005. <br />The factors used in the model were selected based on actual conditions of the Shaft #3 site. The <br />cttt slope above the shaft site is primarily sandstone outcrop, with the remaining area covered <br />with an aspen fiber erosion control blanket, and soil with approximately 30 percent vegetation <br />cover. According to the SLDCAD model the amount of sediment generated is 0.64 mill, which <br />is slightly above the tttinintum standard of 0,5 ml/l. It should be noted that the West Clk brine <br />has received a lot of rain itt the last two weeks, and there is no evidence of significant erosion or <br />sedimentation around the site. However, MCC will install a plunge pool along the flow line of <br />the seditncnt ditch prior to culvert CSLY-22 to settle out a majority of the sediments to ensure <br />that the site is not contributing excess sediment to the drainage basin. MCC has used these <br />plunge pools successfully at the Lower Refuse Pile and at the main topsoil stockpile. <br />Please calf if you have any questions. <br />Sincerely, <br />~~, <br />Christine E. Johnsto <br />I:nviroumcntal Eng r <br />cc: Henry Darbe <br />Phil Schmidt <br />UB6J.doc <br />