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AA Mine'V" a ei- <br /> AA <br /> https.Ilwebsoilsurvey.nres.usda.gov/by providing a soil map and soil unit profile <br /> description printouts. <br /> Due to the nature of this historic mining site (disturbed by historic mining since 1870s), <br /> undisturbed adjacent surface materials have no available topsoil and are comprised of <br /> historic mining waste. <br /> Also,there are no mapped soil resources in the area on websoilsurvey.nres.usda.gov <br /> due to the extreme altitude at 12,000 feet elevation above sea level. <br /> b. Provide any known information regarding the topsoil depth replacement and <br /> revegetation success of the reclaimed London Mine tailings located off-site to the <br /> southeast of the processing area. <br /> MineWater reached out to CDRMS Abandoned Mine Program(Erica Crosby) and found <br /> that the London Mine tailings revegetation program had the following characteristics: <br /> Ground was broken and a borrow pit developed nearby,at 11,000 feet elevation,and <br /> 32,000 CY of pit-run material was screened to produce 11,330 CY of fines.A portion of <br /> the rock fines were then placed on the tailings to a depth of about 6 inches with the <br /> remaining fines required for reclamation of the borrow pit disturbance area,and the <br /> following year were amended with compost(including biosolids)from Summit County <br /> at a rate of 160 cubic yards per acre as a growth medium. Following seeding with Zone <br /> 6 alpine mix,the surface was covered with 2,000 Ibs per acre of weed-free straw and <br /> then crimped to a depth of 2 inches. <br /> This information was added to the updated Exhibit D Reclamation Plan. <br /> c. Please provide a discussion on any projected impacts(compaction, loss of nutrients, <br /> heavy metal contamination, etc.)that the South London Stockpile has had on native <br /> material underneath the stockpile for the substantial amount of time the stockpile has <br /> existed. <br /> MineWater has carefully observed the toe of the existing stockpiles and found no <br /> adverse effects on vegetation density or diversity.Applicant anticipates that heavy <br /> metal contamination will not prevent the use of these soil resources based on water <br /> quality(neutral pH,low in metals except zinc,with zinc concentrations not inhibitory <br /> for plant growth).Applicant plans to amend the existing soil resources as needed to <br /> ensure that the material can sustain vegetation through addition of appropriate <br /> amendments based on soil testing. <br /> This will likely include amendment to attain a level of organic carbon and other <br /> nutrients through addition of organic matter such as compost.This strategy was <br /> effective for pit-run rock fines(having no organic carbon content)amendment with <br /> compost at the London Tailings project implemented by DRMS in 2014.We anticipate <br /> that buried soil that we hope to find beneath the South London Stockpile will perform <br /> better than pit-run fines for the purpose of establishing vegetation on the final cover. <br />