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MONTGOMERY WATSON <br />Mining Group <br />Date: 13-Mar-00 <br />To: Seneca Coal <br />C6 <br />From: Craig Burger and Tom Leidich <br />Subject: Yoast Mine Sedimentation Pond 12 Construction Quality Assurance <br />The purpose of this memorandum is to present the results of quality assurance testing performed <br />during the construction of Sedimentation Pond 012. <br />A representative material sample was collected from the embankment of Pond 12. Soil classification <br />and standard Proctor tests (ASTM D698) were conducted to assist in the QA/QC procedures to <br />assure that the placement of fill meets the design and engineering compaction specifications for the <br />approved designs in the PAP. Seneca and Montgomery Watson personnel collected [he sample and <br />Golder Construction Services, lnc. conducted the testing. These tests resulted in a maximum dry <br />density of 106 pcf. The results of the Proctor tests are included in Attachment A, Quality Assurance <br />Test Results. <br />Seneca Coal Company constructed Pond 012 during August and September 1999. Montgomery <br />Watson Mining Group was retained to conduct density testing during the construction efforts. The <br />following is a chronology of testing events and results of the testing conducted as the pond <br />embankment was constructed. <br />7(29(99 -Four material samples were collected for particle size and Atterberg Limit analysis to <br />verify [he design parameters assumed during the engineering of the pond embankment. Two <br />samples were collected from the embankment keyway and two samples from [he borrow area within <br />the proposed pond area. The results of these analyses are included in Attachment A. <br />8/20/99 -Two nuclear moisture/density tests were conducted using a Troxler Gauge. The tests were <br />taken approximately six feet below final crest elevation on the right and left sides of the <br />embankment. Both test results were within 95% of the maximum dry density value of 106 pcf. <br />8/25/99 -Two nuclear moisture/density tests were conducted using a Troxler• Gauge. The tests were <br />token at [he approximate final elevation of the crest on the right and left sides of the embankment. <br />The test on the south end of the embankment was slightly below 95% of the maximum dry density at <br />94.3%. The test at [he north end of the embankment was at 102.8% of the maximum dry density of <br />106 pcf. Neither the principal or emergency spillways had been installed yet. <br />• <br />LW.4ZWnnJ~ A~hI~WmA3nnJ rz [)uaLn .1 ~.u.nm r Flrmn Jn. <br />