2016-05-23_HYDROLOGY - M1980244 - Laserfiche WebLink

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`SNE WMON T Newmont Mining Corporation Cripple Creek&Victor Gold Minrig Co Env rormeni end Socia'Respois bnit} 100 N 3 Street P 0 Box 191 Victor CO 80850 T 719-689-2977 F 719 689-3254 SENT CERTIFIED, RETURN RECEIPT REQUESTED 7015-1660-0000-0779-6900 19 May 2016 RFC=JVED Mr. Timothy Cazier, P.E. gRAY 2 3 2016 Environmental Protection Specialist DIVISION OF RECLAMATION Colorado Department of Natural Resources MINING AND SAFETY Division of Reclamation, Mining and Safety Office of Mined Land Reclamation 1313 Sherman Street, Room 215 Denver, Colorado 80203 1 Re: Permit No. M-1980-244; Cripple Creek & Victor Gold Mining Company ("CC&V"); Cresson Project; -response to DRMS question on drainage from the southeast corner of the High Grade Mill Pad (HGM) Dear Mr. Cazier: As a follow up to the CC&V response provided on February 24, 2016 and subsequent conversations, on the above referenced topic, during the inspection of March 15, 2016 (and restated in your inspection report) we offer the following: 1. Issues with water seeping from the edge of the mill liner system primarily occurred during the period Q2 to Q4 of 2015. During Q2 the sump was known to be reading elevated levels. The high level was thought to be due to high infiltration flows stemming from the unusually high precipitation the district received. Initial investigations were conducted to look at upsizing the installed sump pumps to handle the perceived flow. As the weather pattern turned and precipitation levels dropped off issues with the sump level remained. At this time it became apparent the elevated levels were not do to meteoric infiltration and must be stemming from a leak in piping within the lined area. No indication of process solution, e.g. elevated pH, cyanide, etc., were ever detected and internal water balances within the mill showed no indication of a leak suggesting the most likely source was within the fire protection loop. Inspection of the hydrants surrounding the mill showed that water was bubbling to surface near the hydrant on the north east corner of the mill. The area was excavated and a repair was made on a failed tee connecting the hydrant to the main loop. Overall water supply issues were improved, the sump level began dropping immediately thereafter, and evidence of seepage around the liner abated. The level stabilized and remained through much of Q3, but the level