2007-04-09_GENERAL DOCUMENTS - M1986141

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Sherman Mine Regrading Project Kessler Reclamation was the low bidder on the regrading project, which simplified the transition between projects. The completion of the demolition project and start of the regrading project overlapped each other by approximately one week. The regrading project encountered a variety of surprises and challenges, including a large quantity of trash which had been buried on site, an extensive wooden trestle which had been covered in mine waste, rock outcrops and an area of frozen mine waste. One change order to the regrading project was issued which addressed construction of a channel across the regraded mine waste to conduct the water flowing out of the ventilation portal. This water flow was not apparent during the initial investigation, or during the 2007 construction season. Not until the blowout occurred in July did this water become an issue. Conducting approximately 400 gallons per minute across the reclaimed mine waste required construction of a ditch approximately 4 feet wide across the bottom and 10 feet wide across the top, and approximately 500 feet long. During the regrading project, the Colorado Youth Corps came to the site for a week to assist in trash collection and removal of the upper portion of the retaining wall. Their work was greatly appreciated. Kessler Reclamation's flexibility in handling the unforeseen conditions contributed to the orderly flow of the project, as well as its timely completion. V. Feature Closure Summary— See Table. M:\imp\Costs FeatureClosures\Sherman Mine Reclamation FeatCloseSummary.xls M:\imp\Costs FeatureClosures\Sherman Mine Regrading Cost FeatCloseSummary.xls VI. FUTURE MAINTENANCE RECOMMENDATIONS The blow out of the ice plug in the ventilation portal demonstrates a serious potential problem. If the ice plug forms again, the resultant blow out will likely damage the site. A solid door was installed on a 60 inch corrugated metal pipe (culvert) which was backfilled, in and effort to prevent freeze up in the future. The ventilation portal should be monitored for conditions leading to freeze up of the portal, and if they appear to be occurring, an upper portal can be blocked off to reduce the amount of air allowed to flow through the mine. After the revegetation has stabilized, the site should be re-assessed to determine if shrub planting should be undertaken. One potential source of revegetation efforts would be the local Colorado Mountain College Natural Resource Management Program acting in cooperation with the Bureau of Land Management. They could conduct additional revegetation efforts and annual vegetation monitoring of the Sherman Mine Project area. In addition, periodic DRMS inspections will be made to ensure the integrity of the closures remain intact.