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Jared Ebert <br /> September 16,2019 <br /> Page 3 of 11 <br /> b. DRMS Response: The revised mine plan was not updated to clarify the discrepancy, page D-4 still <br /> indicates the highwall will be no more than 4,000 feet in length and the table of page D-6 still indicates <br /> the highwall and adjacent cell walls will be 1,500 feet in length. This issue was not addressed. <br /> Al Response: Page D-4 has been revised to the 1,500 foot length as noted in the table on Page D-6. <br /> c. DRMS Response 2: The revised table on page D-5, for Aspect A indicates the disturbed area will be <br /> 6215 acres. The Division assumes this is a typographical error. Please revise the table as necessary. <br /> Al Response: The table on page D-5 has been revised to show that the disturbed area for Aspect A is <br /> 30 acres. <br /> Rule 6.4.7, Exhibit G, Water Information <br /> 15. Similar to the adequacy item for the mining plan section about wet-mining the South Area and <br /> dewatering operations. Please clarify if any dewatering will occur at the South Area? If dewatering is <br /> planned for this Phase, an evaluation of the impacts of this activity and possible mitigation measures <br /> will need to be addressed in this Exhibit. <br /> a. Al Response: The south area will be dewatered as described above. Dewatering water pumped from <br /> the South Mine Area will be discharged to the downstream end of the Brighton Return Ditch (See <br /> Exhibit C-4) near the east end of the mine limit. The water will flow directly into the South Platte River <br /> via the Brighton Return Ditch. <br /> b. DRMS Response: Revised page G-2 indicates the South Mine Area will be dewatered and water will <br /> be discharged at the upstream end of Brighton Ditch which contradicts your response noted above. <br /> Please clarify the discrepancy. <br /> Al Response: The dewatering water will be discharged to the Brighton Return Ditch the at the south <br /> east property line see Exhibit C-4, or in a parallel discharge pipeline located within the ditch easement. <br /> c. DRMS Response 2: The groundwater model conducted in 2004 does not reflect the plan to dewater <br /> the South Mine Area and Al notes there are four wells that could be impacted by the proposed <br /> dewatering operation (revised page G-2). Also, revised page G-5 indicates dewatering of the South <br /> Mine Area will likely impact wells west of the South Mine Area. Al's plan provides mitigation measures <br /> should the wells be negatively impacted. Given the proximity of these wells to the mining/dewatering <br /> operation and the shallow nature of the alluvial aquifer, it seems given that the adjacent wells will be <br /> negatively affected. Please assess and/or model the impact the dewatering operation will have on <br /> these wells and devise a plan to preemptively mitigate possible impacts to the use of these wells and/or <br /> provide a thorough demonstration the wells will not be impacted. <br /> Al Response: Al acknowledges that the wells near the South Mine Area will likely be impacted by the <br /> dewatering operations. The preemptive plan to address the potential impact will include the installation <br /> of cisterns on each of the nearby wells. Figure G-1 presents the preliminary design developed by Tetra <br /> Aggregate Industries—WCR,Inc <br /> 1687 Cole Blvd Suite 300 <br /> Golden,CO 80401 <br />