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Jared Ebert <br /> September 16,2019 <br /> Page 5 of 11 <br /> One dimensional steady state ground water flow equations commonly used in construction dewatering <br /> were used to size the drainpipe. The calculations are presented in Appendix G-1. The analysis <br /> indicated a drain pipe diameter of six inches would be adequate. <br /> 18. The applicant indicates under the second bullet on page G-5 that if a subject well has not been put <br /> to beneficial use prior to mining, then they would have no responsibility to provide mitigation for <br /> groundwater impacts. Please remove this sentence as it is incorrect. <br /> a. Al Response: The sentence has been removed as requested. An updated Exhibit G is attached for <br /> your review. <br /> b. DRMS Response: The sentence was not removed as requested (see revised page G-6). This issue <br /> remains outstanding. <br /> Al Response: The sentence has been removed as requested. <br /> 20. Please update this discussion about the groundwater monitoring plan beginning on page G-5 to <br /> indicate the frequency the groundwater monitoring wells will be monitored. <br /> a. Al Response: Groundwater monitoring wells will be monitored monthly until mining commences and <br /> quarterly thereafter. This information is reflected in Exhibit G. <br /> b. DRMS Response: The quarterly water level monitoring frequency proposed after mining commences <br /> would not adequately detect impacts to the water levels on an appropriate time scale to trigger <br /> mitigation. Please revise the groundwater level monitoring plan to conduct weekly water level <br /> monitoring for the monitoring wells around the south mine area during dewatering and until <br /> groundwater levels have recovered once dewatering ends. For the wells around the East and West <br /> Mine area, monthly water monitoring would continue to be appropriate. If sufficient data is collected <br /> during the life of the mining operation, and a demonstration can be made that impacts to the <br /> groundwater system have been minimized, the Division would consider approval of a Technical <br /> Revision to revise the water level monitoring frequency at a later date. <br /> Al Response: So noted, Al agrees to comply with this comment. <br /> Rule 6.4.12, Exhibit L—Reclamation Cost Estimate <br /> 29. The reclamation cost estimate submitted is based on the Applicant's projection of the maximum <br /> liability. It is discussed that this will occur at the end of mining in the East cell (Phase 3) area. The cost <br /> estimate assumes the Phase 1 area has been backfilled and the slurry wall has been installed around <br /> the Phase 2 and 3 area. It is very unlikely the point of maximum liability will occur at the time the <br /> applicant proposes. Case in point, the Division currently holds a bond for the site to cover the backfill <br /> and grading of the small 3 acre pit located in Tract M area on the north side of the East Area in the <br /> amount of$326,040.00 for this disturbance. For the proposed first phase of the operation, the Applicant <br /> proposes to mine in the south area and affect 24.3 acres in this area, at this point the pit in the north <br /> Aggregate Industries—WCR,Inc <br /> 1687 Cole Blvd Suite 300 <br /> Golden,CO 80401 <br />