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..,. ~~' <br />Richard D. Lamm <br />Governor <br />Permit#: K^ 9-Z7-~O Confidental?: <br />Class: Type-Seq.: <br />DEPARTMENT OF NATURAL From: t-C ~ To: <br />Doc. Name _ /rJ`razAC lKeo-C~ <br />David H. Getchea, Executive Director Doc. Date (if no date stamp): 9 - !O" ~ <br />MINED LAND RED <br />DAVID C. SNELTON, Director <br />DATE: September 10, 1984 <br />T0: Mark Loye /% <br />FROM: Jim Pendleton ~/~--- <br />RE; Geotechnical Aspe of <br />Responses for ' itch Min <br />Permit No. 77-4HR" <br />~~ <br /> <br />Homestake Mining Company's Supplemental <br />e Reclamation Plan Amendment to <br />Pursuant to your request, I have completed a review of the geotechnical <br />aspects of Homestake's responses to our original adequacy comments on their <br />requested reclamation plan amendment. <br />The operator has satisfied many of my concerns expressed in the earlier <br />memoranda of March 28, 1984. Several deficiencies remain to be resolved, <br />prior to approval of their amendment request. <br />(1) Success criteria for landslide stabilization: Call and Nicholas, Inc., <br />consultant to the applicant, recommends that the landslide mass be <br />considered stable when movement has slowed to less than 6" per year. <br />(2) Monitoring of landslide stability: Call and Nicholas, Inc., also <br />recommend that the landslide stability be monitored at at least 5 <br />points on a quarterly basis. However, the applicant should prepare a <br />map which clearly depicts the location of the points to be monitored. <br />(3) Consolidation/Settlement: The applicant believes that <br />consolidation/settlement of the fills and landslide body will be <br />insignificant and do not warrant specific adjustment of the proposed <br />plan. The applicant does not present any analytical demonstration of <br />their consolidation/settlement predictions. I believe it appropriate <br />to require survey monitoring of appropriate points in locations <br />potentially susceptible to consolidation/settlement, in order to verify <br />the applicant's projection of insignificant movement. <br />(4) Low grade ore stockpiles: The applicant projects that the low grade <br />ore would not produce significant leachate, even if no clay cover were <br />placed upon the pile. Further, the applicant believes that the <br />diversion of surface drainage around the piles should provide <br />sufficient protection against erosion. Based upon the indication by <br />the Colorado Department of Health that the low grade ore does not <br />constitute hazardous material, the Division considers the proposed plan <br />acceptable. <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (30~) 866-3567 <br />