2014-02-24_REPORT - C1981022 - Laserfiche WebLink

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During 2013, the mine was sealed or idled for most of the year. An assessment of mine inflows was not possible during 2013 but it is likely similar to 2012. See the D2B and D2B2 well discussion above for information regarding the transfer of collected Elk Creek mine sump water to the abandoned Somerset B/C seam workings. Otherwise, the groundwater encountered in the mine is fairly minimal and randomly distributed. Perched water bearing zones are sometimes encountered (as expected) with significant initial flows, but they seem to dewater fairly quickly. Outfall 011 — Sanborn Creek Mine Water Discharge Outfall 011 was the OMLLC - CDPS mine water discharge point from Sanborn Creek Mine that discharged into Sanborn Creek The Sanborn Creek Mine water drainage system was decommissioned on May 21, 2003. Since the mine completed the last panel, the underground hardware was removed and the entries were sealed in accordance with MSHA requirements. During 2004, CDMG approved PAP TR -45 which removed Outfall 011 as a monitoring point. Outfall 015 — Elk Creek Mine Water Discharge Outfall 015 is a CDPS mine water discharge point for the Elk Creek Mine. The mine water discharge point provides for the discharge of mine water to Elk Creek. The Outfall 015 has never discharged. Outfall 015B — Elk Creek Mine Dewater Boreholes. CDPS Permit No. CO- 0000132 is the primary, current Permit for the Oxbow Mining, LLC., Elk Creek Mine. Outfall 015 is the primary dewater borehole for mine water. Due to unforeseen mine conditions and circumstances related to a spontaneous combustion event and temporary sealing of the mine by the Mine Safety and Health Administration (MSHA) Oxbow had proposed a temporary re- location for the mine water discharge Outfall 015 borehole to aid in mine recovery efforts. As Permit CO- 0000132 was expired and operating under an Administrative Extension, CDPHE could not "modify" an expired Permit. Oxbow was instructed to submit an application for an alternative Outfall 015B. The alternative dewater borehole Permit application (March 26, 2013) resulted is the issuance (on April 16, 2013) of Permit COG - 850064 for an alternative Outfall 015B. The resultant dewater borehole pump(s) operated from June 3, 2013 until September 9, 2013. Approximately 58,879,900 gallons (180.6 acre -feet) were subsequently pumped from the mine and discharged to upper Elk Creek. The pumps were later pulled and all hardware removed from the drill pads. On January 31, 2014 a request was submitted to CDPHE to terminate COG - 850064. During the active pumping of the dewater boreholes, the water monitoring and reporting were conducted in accordance with the terms and conditions found in the COG - 850064 Permit. 18