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Refuse disposal within the Roadside Refuse Disposal Area (RSRDA) was completed in the eazly <br />1980's, and the slopes of the pile were temporarily stabilized. The flat top of the RSRDA is a <br />permitted supply storage azea. Final reclamation of the slopes of the RSRDA, including installation of <br />approved terrace drains, was completed in the fall of 2002. A stability analysis for the RSRDA is <br />provided in Appendix 13-4. Final grading is discussed in Tab 14. <br />The lower three benches of CRDA-1 and CRDA-2 were covered with the approved thickness of non- <br />toxic cover, seeded, and mulched in the late summer/fall of 1994. Final reclamation of the upper <br />benches was conducted in the spring of 2002. <br />Geotechnical analyses for CRDA-1, and CRDA-2, aze provided in Appendices 13.4 and 13-5 of the <br />application. CRDA-1 has been constmcted with three rock underdrains, and construction <br />specifications include 2:1 slopes with 10' wide benches on 30' vertical intervals. The benches are <br />sloped to the inside and graded to drain to perimeter ditches along the sides of the pile. CRDA-2 <br />specifications are similaz, with the exception that pile design does not incorporate underdrains, and <br />slope between benches is not to exceed 2.5:1. <br />Stability concerns associated with higher than anticipated water levels in Piezometer CRDA-O1 <br />resulted in suspension of waste disposal at the site in 1988, pending drainage modifications and <br />stability re-evaluation. Between 1988 and 1993, the lower three benches were regraded to provide for <br />better slope stability and drainage. Surface drainage was improved by the construction of diversion <br />ditches that allow surface runoff to exit around the pile instead of contacting the face. <br />A stability evaluation was performed in the spring of 1994 by Western Engineers, Inc. As a part of the <br />study, pump testing was conducted in existing piezometers and 30 additional piezometers were <br />installed to evaluate phreatic surfaces and pore pressures. The results of the study showed the pile to <br />be stable as designed. Critical water levels were defined for each of the 30 new piezometers. Based <br />on the study results, the operator was permitted to resume waste disposal at CRDA-1 in 1994. The <br />operator has committed within the permit to monitor the 30 piezometers quarterly, and if water level in <br />any of the piezometers reaches critical tazget depth as listed on Table 18-4, stability of the pile will be <br />reevaluated and corrective action taken if necessary. <br />CRDA-1, and 2 will be monitored throughout constmction. Monitoring will include <br />1. Piezometric monitoring of the coal processing waste embankment; <br />2. Monitoring of side slopes to maintain a maximum slope angle of 2:1 between benches on <br />CRDA-1, and 2.5:1 on CRDA-2; <br />3. Monitoring compaction of constmcted lifts; and <br />4. Quarterly inspection for stability and compliance with approved plan by a registered <br />professional engineer. <br />Geotechnical analyses included in the permit application show that CRDA-1 and CRDA-2 are stable <br />at a minimum safety factor of 1.5. The following specific findings apply to the approved refuse <br />disposal azeas, <br />The disposal azea will be inspected on a regulaz basis by a qualified professional specialist under <br />the direction of the professional engineer, experienced in construction of similaz earth and waste <br />structures. Inspection by this person has been approved by the Division as appropriate <br />39 <br />