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_.I r • Mr. Edwards Bischoff Page 2 ~, JuSy 15, 1987 4. A polyethylene plastic geomembrane liner with thickness of 30 mils was placed over the prepared ground surface in a manner i that assured a minimum of handling so that the interior of the tailings pond was not disturbed. 5. The geomembrane liner was closely fitted and sealed around the only outlet In the liner. There ere no other projections through the fallings pond liner. 8. The portions of the geomembrane liner that were damaged during installation were removed and repaired with additional pieces of 30 mil polyethylene lining materiel. 7. The separate panels of the geomembrane liner were sealed together with a heat fusion method that employed a digital temperature controlled hot shoe plastic welder. 8, The lap Joints of the polyethylene panels were formed Dy overlapping the edges of the panels a minimum distance of 12 inches. 9. The contact surfaces of the lap Joints were wiped clean so that all dirt, dust, end other foreign materiels were removed prior .-. to heat fusion seaming. 10. Sand bags are being used to keep the geomembrane liner In position during windy conditions prior to completely Pilling the impoundment area with mill tailings. 11. Any necessary repairs to the polyethylene geomembrane liner will be patched with similar liner material, end will be repaired in the same manner used during the initial installation, 12. When the tailings pond is expended, the upper edge of the geomembrane lining will be used to seam additional panels to the previously installed polyethylene ]finer material. 13. During the construction of the tailings dam, the granite bedrock was ripped and exposed along the entire length of the tailings impoundment area. Because the exposed bedrock would not permit gravity drainage, the excess water decantation line was placed in position along the high side of the interior of the tail- ings pond on top of the installed geomembrane liner. The geomem- brane liner is sealed io the horizontal section of the water decan- tation pipe where it passes through the tailings dam, end several seep rings were attached to the pipe to prevent fallings from piping along the decantation line. A 30 mil polyethylene geomembrane was selected to Ilne the tail- /` lags impoundment Brea rather than the originally proposed plastic liner composed of polyvinyl chloride. The polyethylene liner has better ultra- violet light resistance characteristles than the polyvinyl chloride liner