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yin <br />iii iiiiiiiiiiiu iii ~ <br />Gilbert F. Rindahl, P.E. <br />C. Jay Silvernale <br />Bruce G. Rindahl <br />Rindahl & Associates 2305 S. Syracuse Way Suite 217 Denver, CO 80231 13031 696-68-06 <br />RECEIVED <br />October 23, 1984 <br />Mr. Edward Bischoff <br />Mined Land Reclamation Division <br />423 Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80203 <br />RE: Neglected Mine - File No. 81-165 <br />Dear Ed: <br />OCT 2 ~ 19~-'~1 <br />MINED LAND RECLAMATION DIVISION <br />Colo. Dept. of Natural Resources <br />Request a Technical Revision to the approved mine plan for <br />Permit No. 81-165. The process to cyanide leach the area has <br />been changed as follows: <br />The system is considered a closed circuit system. <br />Old waste is crushed and agglomerated with cement and <br />lime and placed on the heap. <br />Solution is mixed in storage tanks where it is then <br />pumped to the spray bars over the heap. Solution is <br />pumped from the base of the heap to the carbon columns <br />where it is stripped and then returned to the storage <br />tanks. <br />Leach solution will not be permitted to exceed a depth <br />of four feet in order to insure the design flow is not <br />exceeded. <br />The pit for the heap is lined with 30 mil hypolow with a leak <br />detection pipe under the lowest point of the pit. An asphalt <br />lined concrete block wall has been erected and leak tested around <br />the mixing tanks and carbon columns. The mixing tanks are capped <br />and locked. A 6' chain link fence has been installed around the <br />leach pad. This fence is topped with one strand of barbed wire. <br />An additional strand will be added in the spring of 1985 when <br />weather permits. <br />c.u• <br />~`' •, <br />^, ~~i <br />Engineering & Environmental Services a„c•` <br />