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Greeley 351h AM -02 Adequacy Letter <br />Page 3 of 5 <br />September 11, 2014 <br />6.4.7 Exhibit G - Water Information <br />11. The Division's engineering staff reviewed Attachment A — Groundwater Monitoring and <br />Mitigation Plan and Attachment C — MODFlow Results. A copy of the review memo from <br />Tim Cazier, P.E. is attached. <br />12. The Applicant states there are six (6) domestic wells and five (5) irrigation wells within 600 <br />feet of the site. Please provide a mitigation plan with trigger levels for the potential impacts <br />to the surrounding groundwater wells. The Applicant must explain any mitigation measures <br />to be implemented and trigger points which would put mitigation measures into effect. <br />Typically, a trigger point of a 2 feet change from historic ground water levels is acceptable. <br />13. The Applicant states Martin Marietta has two (2) monitoring wells on the west and south <br />side of the West Cell of the Greeley 35th Avenue Property, in addition to seven wells in the <br />vicinity of the West Pit that were installed in support of the Iverson Mine. Please provide a <br />map of the monitoring well locations. <br />The Division records indicate four (4) monitoring wells west of West Cell and no monitoring <br />wells south of the West Cell. Please explain this discrepancy. During the Pre - Operational <br />inspection, GEI stated one of the monitoring wells was mined through, please indicated this <br />well on a map. A copy of the Exhibit C — Pre - Mining Plan Map dated 12/11/2009 submitted <br />with the Amendment No. 1 application indicating the well locations is attached for <br />reference. <br />14. Please provide mitigation measures for the potential groundwater mounding and <br />shadowing effects due to the proposed slurry wall to be implemented and trigger points <br />which would put mitigation measures into effect. The mitigation measures must include a <br />scenario for the installation of a French drain to direct groundwater around the slurry wall <br />and restore groundwater levels to the historic elevation in area of groundwater mounding. <br />15. The Applicant states the continued monitoring of the monitoring wells for the purpose of <br />the Groundwater Monitoring and Mitigation Plan is not required by the DRMS. This <br />statement is not accurate. Martin Marietta committed to submit monthly groundwater <br />monitoring data with the required annual report during the previous amendment (AM -01) <br />application. <br />During the Pre - Operational inspection, Ms. Mikulas with Martin Marietta stated <br />groundwater monitoring data would be provided from 2009 to present and groundwater <br />data would be included with the annual report for the site in the future. <br />16. As discussed during the Pre - Operational inspection, the Division recommends the current <br />Groundwater Monitoring and Mitigation Plan approved during the previous amendment <br />