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Pitch Reclamation Project -Sediment Control Embankment November, 2002 I.0 INTRODUCTION 1.1 Background The Homestake Mining Company (Homestake) Pitch Reclamation Project is located about eleven miles south of Sargents, Colorado, and is within [he headwaters of the Indian Creek drainage basin which drains westwardly into Marshall Creek. The project area is at about Elev. 10,000 ft with facilities consisting of reclaimed low-grade ore piles and waste rock areas, a mine pit, access roads and a sediment control pond. The sediment control pond serves as the final collection point for surface waters from the project area prior to being released to the receiving waters downstream of the project. It is located on Indian Creek just down gradient of the confluence with Tie Camp Creek. The purpose of the pond is for sediment control from the property and water quality monitoring for compliance with the Project's discharge permit. The embankment that forms the pond is of sufficient height to be under permit and operating jurisdiction of the Colorado Department of Water Resources (CDWR) with respect to annual • inspections and reports of performance. Annual reports to CDWR refer to the structure as Wastewater Treatment Impoundment Dam I.D. 280110. During the annual site inspection by the CDWR State Engineer (Montrose Regional Office) in the summer of 2000, a wet area was noted on the downstream face of the embankment. The wet area was located about mid height of the downstream slope in the vicinity of the maximum section of the embankment. Homestake retained The Glasgow Engineering Group, Inc. to observe the azea and evaluate the possible source of the moisture and to determine whether there was any potential impact to the safety of the embankment. The initial site visit for review of the embankment was conducted in September, 2000 with follow up field explorations conducted in October. It was determined that the wet area was a result of a preferred seepage path through the core of the embankment and that control of the seepage would be required for the embankment to remain in operation at full capacity. A remedial design was developed to line a portion of the upstream face of the embankment as a means for blocking the preferred seepage . path. Construction was delayed, however, due to the onset of winter weather conditions at the site. Therefore, an operating and monitoring program for the embankment was developed and implemented The Homestake Mnaing Company -t- The Glasgow Eng6teering Group, lnc.