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ATTACHMENT (a Fly -4- Page 49: The post-closure ground water monitoring period was not specified. Page 50: A land surveyor inspection is to be conducted as part of post closure monitoring. The report of this inspection should also include the horizontal accuracy and the contour interval for determining the ground water gradient and surface drainages after closure. APPENDIX E, HINKLE REPORT Page 2: The designated borrow area in Figure 1 overlaps the proposed disposal areas for auger cuttings. The borrow area must be relocated. Page 3: Alternative 1 specifies that fill well be placed in 12 inch lifts but does not specify the type, weight and number of passes of the compactive equipment or the percentage compaction required. The lifts may be too thick to achieve good bonding between the lifts which is dependent on the equipment. Page 5: Alternative 2 includes installation of a clay cut off wall . Subchapter 15, Section 2545(b) requires these walls to be two feet thick and must be keyed a minimum of five feet into natural geological material . Page 7: Alternative 3 consists of removing soil to a depth of six to eight feet. Figure 4 depicts the RCRA cell as located in the Pond 2S Area. Figure 12 to 13 of this report show that this location has concentrations of barium, cyanide and tetrachloroethylene exceeding the maximum and statistical background concentrations. The report is not clear about the placement plans for the potentially contaminated, excavated soil . Page 10: Alternative 3 includes a sand or geogrid drainage layer to serve as a leak detection system. Hargis should consider using gravel over sand, as sand may tend to clog more readily due to bacterial growths. The gravel should be clean. Page 10: Alternative 4 does not include a two foot clay liner which is required by Subchapter 15, Sections 2541(e) and 2542(b) . If this alterative is chosen, it must be demonstrated that the alternate design and operating practices, together with the location characteristics, will prevent the migration of hazardous waste constituents into the soil , ground water of surface water at any time. Page 10: Alternative 4 states that on site soils when compacted have a 10'9 cm/sec permeability which would be an effective seal . This data is apparently based on three remolded laboratory permeability tests and not on field compacted soils. A recent publication (Elsbury and Sraders, Building a Better Landfill Liner, Civil Engineering, April 1989) states that samples compacted in the laboratory can be a poor indication of actual field permeabilities.