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Mr. Daniel Hernandez <br />May 25, 2012 <br />Page 6 <br />Table 3. DWDA Recommended Construction Criteria <br />Configuration <br />Maximum height 50 ft <br />Maximum slope (H:V) 2.0(H): 1.0(V) <br />Placement <br />Maximum lift thickness 2.0 ft <br />Minimum compaction 90% standard proctor <br />Moisture content for compaction +/— 2% of standard proctor optimum <br />1. It is recognized that the proposed DWDA embankment would be constructed over the <br />existing footprint and therefore the majority of the foundation has been previously <br />prepared. However, to provide an adequate foundation - bearing surface, around the <br />perimeter, the topsoil, loose fill, man -made debris, organic material, and all other <br />deleterious material must be removed prior to development waste rock placement. If soft <br />or low strength soils are encountered, they should be removed to a more competent and <br />suitable depth. Unsuitable material should be placed in a pre- designated area. <br />2. Upgradient surface water should be routed away from or around the waste rock pile by <br />adequately sized diversion channels. <br />3. The development waste pile should be graded to shed surface water and precipitation off <br />all portions of the pile both during and after development waste rock placement. <br />4. Development waste rock should be placed near its optimum moisture content as indicated <br />in Table 3. Waste rock material placed significantly above or below the optimum <br />moisture content likely will not achieve adequate compaction or shear strength. Once a <br />suitable moisture content is achieved, development waste should be sealed (by <br />compaction) to minimize infiltration from precipitation and should be graded to shed <br />water per the drainage plan. <br />5. AAI must be notified if a waste rock pile geometry different than the one evaluated and <br />discussed in this report is considered for construction. Also, if development waste <br />composition, moisture content, or placement techniques change, or any other assumption <br />presented in this report is not valid, AAI must be notified to evaluate the impact on the <br />stability of the development waste pile. <br />This report contains professional opinions based on site visits, laboratory testing, <br />experience and information provided by NECC. AAI makes no warranties, either expressed or <br />implied, as to the accuracy or completeness of the information provided. Opinions are based on <br />subjective interpretations of geotechnical data; other equally valid interpretations may exist. It is <br />acknowledged that these recommendations have been made based on limited data and, thus, <br />there are inherent uncertainties. <br />AAI remains available for consulting during construction, and can assist with field <br />monitoring of ground conditions, as needed. It is recommended that NECC have procedures for <br />field implementation of the report's recommendations. Recommendations provided in this report <br />do not constitute a final design. The recommendations provided herein are based on accepted <br />practice and referenced sources have been cited where appropriate. <br />Agapito Associates, Inc. <br />TR 66 Page E 37 -7 Revised 5/25/2012 <br />