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CDPS EXCEEDANCE REPORT <br />Mine Site: COLOWYO MINE Permit No.: COG-600751 <br />Outfall No.: OOlA <br />Sample Date: 11/14/2007 <br />Sample Taken by: Env. Eng. -Tony Tennyson Laboratory Sample ID: 50711285-001 <br />Exceedences: Total Suspended Solids - 440 mg/L Report Prepared by: Tony Tenn, <br />Explanation: <br />Precipitation records indicate that arain/snow event occurred at Colowyo the day <br />sampling was performed on November 14, 2007. The day the sample was taken rain and <br />snow events were observed (please see attached precipitation data). The storm patterns <br />on the day of November 14, 2007 sample suggest short duration rainfall mixed with snow <br />which caused multiple flows from surface runoff and snow melt (from temperature and <br />precipitation) which caused multiple inflows into the pond from the surrounding <br />designed ditches. Discharge from the pond increased as a result of the storm that passed <br />through the area the day sampling was performed. Precipitation was measured on the <br />November 14, 2007 and sampling was performed at 14:23 PM on November 14, 2007, <br />thus qualifying for consideration of the use of Alternative Effluent Criteria for this <br />sample. <br />Identify Support Info: <br />Relevant laboratory data from Outfal1001A. <br />Precipitation Data from November <br />Proposed Action: <br />Flocculation chemicals approved in the CDPS permit will be added to the pond waters in <br />order to reduce the TSS concentration of the waters that could potentially be discharged <br />from the pond to below the MCL of 35 mg/L in the future. Colowyo is also working with <br />representatives from GE Betz to identify flocculation chemicals and treatment options in <br />order to prevent future TSS MCL exceedences. <br />Stormwater avenues into the pond are being re-evaluated and will be modified as <br />necessary to minimize sedimentation caused by runoff originating from disturbed areas. <br />N:`,C;CC;_[ISGQ\21.t7 ~t~Q(~[:)\21.1 <:`I)PS Permit\31.L2 Inspections & Reports\20(>7\CDPS Lxceedance }2eport_OOL1-&'th Q1'}2.doc <br />