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<br /> <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us <br />John W. Hickenlooper, Governor | Robert Randall, Interim-Executive Director | Virginia Brannon, Director <br /> <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br /> <br /> <br /> <br /> <br /> <br /> <br />MEMORANDUM <br />To: Tim Cazier, DRMS <br />From: Amy Eschberger, DRMS <br />Date: May 03, 2016 (Revised May 31, 2016) <br />Re: Cresson Project, DRMS Permit No. M-1980-244, Amendment-11 Application <br />(Revision No. AM-11), Adequacy Review of Hydrology Sections <br /> <br /> <br />(VOLUME II OF IV) <br /> <br />HYDROGEOCHEMISTRY EVALUATION / DECEMBER 15, 2015 / ADRIAN BROWN <br /> <br />3.4.1 Ground Water Flow <br /> Page 7: The first sentence mentions “three principal historic drainage tunnels” and <br />refers to Plate 4 – Diatreme. However, Plate 4 only shows the Carlton Tunnel. If the <br />other two drainage tunnels were meant to be shown on Plate 4 (as indicated), <br />please revise Plate 4 to show all three tunnels. <br /> <br /> Page 9: Under Item #4 - Overburden moisture content has largely returned to field <br />capacity, the text states “The rapid response to the 2015 spring flooding suggests that <br />much of the overburden in the district has now reached field moisture capacity, and no <br />longer is as effective in attenuating sudden flow events as it was in the prior decade.” <br />Considering this statement, do you expect the response time of Carlton Tunnel <br />flow to be more rapid (similar to spring 2015 flooding) and variable moving <br />forward? If so, does the current water treatment facility have the ability to <br />accommodate such flows? <br /> <br />3.4.2 Water Table <br /> Page 10: At top of page under “The water table illustrates the groundwater flow <br />system”, Item #2, the text states “The water level in the eastern overflow apron in the <br />diatreme appears to remain at approximately the original level, which is substantially <br />below the original (and proposed) ground surface, indicating that the hydraulic <br />conductivity is sufficient for vertical flow away from the surface, but on ly capable of <br />carrying a moderate amount of water into the eruptive centers of the diatreme.” <br />Considering this statement, is it safe to assume that all water infiltrating this area <br />(including the ECOSA) will eventually enter the Cell 3 saturated bedrock ac id <br />neutralization zone? Is there potential for impacted water from the northern <br />portion of ECOSA or WHEX to enter the Grassy Valley drainage system?