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December 3, 2010 <br />COTTER CORPORATION (N.S.L.) <br />FALL 2010 SPILL REPORTING INFORMATION <br />FOR THE SCHWARTZWALDER MINE SITE <br />Introduction <br />This document contains individual spill reporting summaries for unplanned releases of <br />groundwater that occurred at the Schwartzwalder Mine during the fall of 2010. These releases <br />occurred as a result of groundwater capture/treatment systems construction and remedial <br />investigation/mitigation work at the site. Provisions of the current stormwater management plan <br />were effective in preventing any of these releases from flowing overland into Ralston Creek. <br />Alluvial groundwater capture and treatment systems, designed to intercept and help prevent <br />migration of untreated groundwater to Ralston Creek, were operational during the period. <br />Several of these releases essentially amounted to a temporary re-circulation of groundwater <br />within the alluvial fill until it could again be captured and treated before being released to the <br />creek. Within the same reporting period, temporary approval for intentional recirculation of <br />alluvial groundwater to help manage high groundwater tables during construction of water <br />treatment facilities was granted by the Water Quality Control Division (WQCD) and the <br />Division of Reclamation, Mining and Safety (DRMS). <br />A retrospective assessment of circumstances, relevant data, and preventative measures to help <br />avoid accidental releases of untreated groundwater in the future follows the individual spill <br />reporting summaries. <br />Individual Spill Reporting Summaries: <br />PVC Pipe Joint Failure at Sump I <br />Date/Time: September 25 - 26, 2010 <br />Description: A pipe joint break occurred in the groundwater collection system at <br />Sump 1, apparently due to insufficient application of PVC joint cement. <br />Alluvial groundwater flowed into the Sump No. 1 area and adjacent <br />trench (excavated at that time for piping winterization). The water <br />infiltrated back into the alluvium or was pumped back to the water <br />treatment plant for treatment. The release did not flow overland into <br />Ralston Creek. <br />Corrective Action: The pumps were temporarily shut off (September 26, 2010) and the pipe <br />was repaired (September 27, 2010). Pumping was resumed on <br />September 27, 2010 to draw down water levels and pump the water <br />back to the water treatment plant for treatment. <br />Quantity: Estimated 79,000 gallons (in the vicinity of Sump No. 1).