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Dustin Czapla <br />Loesch Pit, M-1981-068, Garfield County, CO. <br />Technical Revision - Pit wall liner <br />Page 4 of 7 <br />Oct. 4, 2010 <br />Mining operations typically took mine walls to a 3H:1V slope. In areas where seepage was <br />occurring, a liner, either a synthetic geomembrane such as HDPE, or a manufactured clay <br />liner such as Bentomax, was placed on the open face of the wall, and extended 3'-5'onto the <br />bedrock floor of the pit. Topsoil cover material was placed over the liner to hold the liner in <br />place and to help restrain hydrostatic head on the outside of the pit wall. Photo 2, below, <br />shows a typically installation of the liner. The side slopes of the excavated pit wall are <br />approximately 3H:1 V, whereas the final graded slope of the topsoil is flatter than 4H or 5H:1 V, <br />with a top width of 10 to 12 feet wide. <br />PHOTO 2 <br />Typical installation of liner on pit wall, and backfill operation <br />WA-MR FWSOURQE GOMMT WM, LLC