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Material will be compacted to a minimum dry density of 90% of the <br />maximum dry density of the material. <br />Quarterly inspections for stability by a registered professional engineer will <br />be completed throughout construction. A copy of the inspection reports <br />will be retained at the mine office and a copy will be forwarded to the <br />Division. As per 4.10.2(2)(a) CRDA -1 and CRDA -2 have been graded <br />and covered in accordance with 4.10.4(4), and topsoil has been <br />distributed on the banks in accordance with 4.06.4, and revegetated, <br />therefore the final quarterly inspection for these piles was performed on <br />December 8, 2010 and November 14, 2008, respectively. <br />The use of CRDA -1 was suspended in 1988 due to stability questions relating to <br />higher than anticipated water levels on piezometer CRDA -01. Additional stability <br />analysis was conducted in the spring of 1994 to answer this question. Western <br />Engineers of Grand Junction, Colorado did pump testing on existing piezometers <br />and installed 30 additional piezometers to evaluate phreatic surfaces and pore <br />pressures. The results of the study showed a complicated series of isolated and <br />interconnected permeable zones, some of which carried water. The end results, <br />using information gathered in the research, showed the pile to be stable as <br />designed. They defined critical water levels in the 30 piezometers which would <br />be grounds for reevaluation of the stability. Monitoring of piezometers is <br />discussed in Tab Section 18 of this application. The use of CRDA -1 resumed in <br />1994. In the event that water level measurements on the 30 piezometers <br />indicated that any have reached the Critical Target Depth listed on Table 18 -4, <br />the stability of the pile will be reevaluated and corrective action taken if <br />necessary. <br />Sediment control calculations are given for CRDA -1, 2 and 3 in Appendix 13 -2. <br />Collection ditches installed during the construction of the pile may not be in their <br />final location. Temporary and permanent collection ditches will be equipped with <br />energy dissipators and /or riprap as necessary to insure stability. <br />MR -76 13 -22 (Rev. 1 /11) <br />