2009-09-14_REVISION - C1981019 - Laserfiche WebLink

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and treat all waters originating from areas disturbed through December 31, 1992. Structures built after August 31, 1992 detain and treat all waters originating from all remaining areas disturbed. The Division finds no significant impacts to surface water quantity due to Colowyo's mining operations. Mined areas will be reclaimed to approximate original contour with the exception of five excess spoil fills. The sizes of drainage areas for some ephemeral and intermittent drainages within the mined area will be changed; however, there will be no changes to drainage sizes for Goodspring, Taylor or Wilson Creeks. The proposed mine plan projects 5,214.8 acres of disturbance during the life of mine. As of the fall of 1991, approximately 503 acres of disturbed land in the East Pit and Section 11 Pit had been reclaimed. As of the end of 1996, a total of approximately 1,066 acres of disturbed lands had been backfilled and graded, and 1,052 acres seeded. As of 2001, 1,376 acres of disturbed lands had been backfilled, graded and seeded. As of 2009, 1,674.44 acres of disturoCU lanes k`f,Jaa.ov tUtd1 (115tUToCC1 acres') nave Deen 0dCKn11eC1 anU graded and 1,668.74 acres have been topsoiled and reseeded (2008 ARR). Runoff in the permit area, which is diverted or detained, will continue to reach the historic drainages. A portion of the water rights held by Colowyo on Goodspring Creek may be consumed in accordance with the augmentation plan discussed in Exhibit 7 of the Permit. The increased infiltration of surface waters is not expected to recharge the ground water system. The Applicant indicates that the increased soil water resulting from increased infiltration rates and increased moisture-holding capacity will be consumed by increased evapotranspiration. The net result is that water is rarely, if ever, given the opportunity to percolate into subsurface material. The anticipated hydrologic consequences to surface water quantity for the South Taylor area are; • Natural springs near the South Taylor Pit might experience increased or decreased flow. • The South Taylor pit will eliminate several springs and seeps. • Hydraulic transmissivity within the backfilled pit will be higher that the adjacent mined area • Base flow in Good Spring Creek will be reduced by up to 7% during and for 45 years after mining • Peak flow in Taylor Creek will be reduced by 2% due to the South Taylor pit Colowyo holds significant water rights on Goodspring Creek should surface water quantity issues develop as a result of mining. Exhibit 7 of the approved permit discusses the augmentation plan for the mine. 2. Potential Effects on Surface Water Quality Information in the PAP and the 1982 Findings Document indicates that surface water quality in the general area is extremely variable. No adverse impacts from mining operations were Proposed Decision and Findings of Compliance 14 September 2009 Permit Renewal 05 Page 40