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'~ J ' of the sample eliminating the buffering effect that these ' hydroxides may have had on the samples. A description of the processing and rinsing methods added to Exhibit D, Section 0.7.3 4j20j89. Section 0.7.4 Heap Leach Pad Design and Construction Section 0.7.4.1 Pad Area ' 26. The narrative specifies that the heap pad area will be approximately 1500 ft. by 1500 ft. (2,250, 000 square ft, or approximately 52 acres). The associated table shows a total pad area of 43 acres. Please clarify. Response: The approximate dimensions presented in the narrative represent the size of the entire heap leach facilities including pads and ponds. The associated table of leach pad areas by stage represents actual leach pad stage areas. As presented on the water balance table in Appendix G a total of 53 acres has been ' calculated for a catchment area to the solution ponds. This number is in approximate agreement with the areas presented in the narrative. Clarification has been added to the narrative and ' the table. Clarification added to Exhibit D Section 0.7.4.1 and Table 0.7.4-1 2/15/89. ' 27. Description of the pad stage connections explains that surface flows will drain from one stage to another through spillways installed in the interstage berms, and ultimately into the pregnant pond. However, the ' Heap P1.an Piew (Figure C-8J, and the Neap Cross Sections (Figure C-9J, indicate that the heap will be a uniform surface, draining along the center drain and perimeter berms. Please clarify. ' Response: Figures C-10 and C-11 (formerly Figures C-8 and C-9) have been modified to show the staged pad drainage as shown in Figures 0.7.4.1-1 through 0.7.4.1-4. Solution conveyance duri ng Stage 1 ' and 2 is provided primarily through the leachate collection drain. Subsequent stages will drain into the Stage 1 or Stage 2 areas through "spillways" or notches cut through the perimeter 1 berms as part of the next stage construction. Figures C-10, C- I1, 0.7.4.1-1, 0.7.4.1-2, 0.7.4.1-3, and 0.7.4.1-4 have been revised to more clearly show the drainage system within the heap. ' Figures C-10, C-11, 0.7.4.1-1. 0.7.4.1-2, 0.7.4.1-3 and 0.7.4.1-4 revised 2/15/89. ' 28. The secondary liner is proposed to be a 12-inch thick nafural soils amended with bentonite to achieve a permeability rating of 1x10-6 cm/sec. It is recommended that a compacted soil or clay not be used as ' a secondary liner as any flows reporting to the leak detection system may cause erosion of the underliner along its flow path. A geomembrane liner is recommended for use as a secondary Liner. Please address, specifically discussing potential secondary Liner damage, and proposed methods of repair shou)d failure occur.