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During the fall of 1988 the chemical feed system was moved into <br />the east portal where it operated effectively during the winter. <br />The pond piping was also revised at that time so it would func- <br />tion during the winter. <br />Snowmass has determined that grouting the portal area in hopes of <br />sealing off sll of the mine seepage is not s viable alternative. <br />The probability of the grouting program being successful is not <br />considered great enough to warrant the expense. <br />Snowmass has decided to revise its treatment system with the ex- <br />pectation that, by providing aeration and additional detention <br />time, no chemicals will have to be added to the mine seepage <br />• water for it to meet NPDES discharge requirements at the dis- <br />charge point. The revision will involve the construction of a <br />long pond between the portal area and treatment pond number 1. <br />The pond will be approximately 600 feet long with a bottom width <br />of about 6-feet, 3H:1V side slopes, and a water depth of 18- <br />inches. The construction of the pond will disturb a corridor ap- <br />praaimately 35-fees wide. The pond will b>_ constructed using the <br />balanced cut and fill technique. Where topography allows, the <br />bottom width of the pond will be increased, however the area dis- <br />turbed will be limited to the 35-foot wide corridor. Aeration of <br />the mine seepage water will be accomplished by installing a sys- <br />tem of baffles at the west end of the pond. Drawing D-2-5 has <br />~ been revised to show the new pond. <br />4-66g Revised 6-19-89 <br />;2 U`~ <br />