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-4- On the design drawing we prepared, the surface ditches have been designed to flow towards the southern side of the processing waste bank and discharge into surface ditch HR-D4 and eventially to sedimentation pond HR- P1 for treatment. Due to some variance between the topography used for design and actual field conditions, a portion of surface ditches around the waste bank had been directed towards the northern end of the disposal area. Empire Energy has constructed a sedimentation pond, northeast of the processing waste bank for treatment of water collected b.y the_noth flowing ditches. We understand that Empire Energy is preparing an "as built"~ ~ drawing which indicates the direction of surface ditch flow and the , sedimentation pond. Photographs 12 through 14 show the surface ditches constructed and the new sedimentation pond. We recommended that the ground surface below the waste disposal area be compacted to at least 90 percent of standard Proctor maximum dry density (ASTM D 698) prior to the placement of processing waste. In addition, we recommend that the processing waste be compacted to at least 90 percent of standard Proctor maximum dry density. The results of field density tests we performed during our site visits are included with this letter. The results of our tests indicate variable percent compaction but generally indicate that the subgrade has been compacted as recommended. We suggest, however, that the subgrade be recompacted_as-the-d_isposal_.ar_ea_expands_ beyond its current .limits prior to_.placing add_iti.onal_prc~cess_ing waste. From field density testing, it appears that the processing waste which has been spread across the southern portion of the disposal area has generally been compacted to the recommended density. It is our understanding that one foot or less of processing waste has been placed. We believe that compaction of additional waste can best be achieved by directing fully loaded haul trucks across the top of previously placed material. In our opinion, lift thickness should be no greater than 2 feet before comp active effort is applied._.We_suggest that initially a soils engineer be_pr_esent during compaction and that density tests be taken to determ.i.ne_the_number of passes of trucks necessary to achieve the recommended compaction. A compaction procedure can then be developed for future compaction. _F_ield density tests should also be taken periodically during_constr-uction of. the waste bank to confirm that the materials are properly compacted. In summary, all topsoil and organic matter has been removed from the processing waste area, as required under Section 4.09.1 (~~) of the MLRB regulations. The subsurface drainage system has been constructed in `genera conformance with our recommendations. Surface diversion ditches have been constructed however, the recommended erosion protection has yet _to~e-fu_1-1.y_pro.v_i.ded. We have recommended that the consti~ucted diversion ditches be surveyed by Empire Energy to confirm that the design cross- section and minimum depth and grade of the ditches has been provided. The foundation for the processing waste has been compacted bui: we recommend that the ground surface be recompacted in advance of expanding the limits of the disposal area. Compaction of the processing waste should be tested by a qualified geotechnical engineer during construction of the pile.