2012-02-27_REPORT - C1981025 - Laserfiche WebLink

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INTRODUCTION MINREC, INC., NORTH THOMPSON CREEK MINES 2011 ANNUAL HYDROLOGY REPORT The Operator completed reclamation of the North Thompson Creek Mines during 1987. The No.1 Mine was sealed during 1987 with the expectation that no water would discharge from it again. The No. 3 Mine was sealed, however pipes were placed in the lowest seal to allow water to drain from the mine. During 1988, the No. 1 Mine filled with water and started to discharge. The portal area was excavated in order to control this seepage. One of the portals and a flooded air shaft were exposed to control the mine seepage. Access to the portal was restricted by locked wooden doors. A four foot thick concrete seal, which "dams" the seepage, was located approximately fifty feet back from the doors. Two three inch pipes with valves penetrated the seal. The flooded air shaft was also a source of mine seepage water. There was a concrete plug in the shaft which water flowed through or around. From 1988 until about 1995 only about 15 gpm would flow around or through this concrete plug. Beginning in 1995 the integrity of the plug degraded and the flow rate from the shaft began to increase. As of June 1998, all of the seepage water from the No. 1 Mine emerged from the shaft. No water is impounded behind the portal seals. The water from the shaft is conveyed to the long pond through a 6 -inch PVC pipe. During late 1998, the Operator backfilled the portal area. A 36 -inch culvert was installed in the fill to provide access to the air shaft and the inlet of the 6 -inch PVC pipe. The remaining disturbed area is a developed water resource area. The developed water resource area encompasses the access road, No. 1 Mine portal, three treatment ponds, sediment pond 9 as well and the pipeline corridor between the No. 3 Mine and the first treatment (long) pond. Current monitoring requirements are shown on page 3 -86 of the permit. Monitoring locations are presented in Volume V of the permit on Map D -4 -23. By letter dated April 20, 2006, the Water Quality Control Division notified Minrec that its discharge permit had been given an inactive status effective March 14, 2005. Therefore, no discharge monitoring was performed during 2006 through 2009. By letter dated April 9, 2008 the Water Quality Control Division directed Minrec to apply for a new discharge permit. By letter dated April 28, 2008 Minrec applied for a discharge permit. The Water Quality Control Division issued Minrec discharge permit number CO- 048233 on December 22, 2009 with an effective date of February 1, 2010. Minrec commenced monitoring mine water discharge during February 2010.