Laserfiche WebLink
Grand River Park Project, M-2006-046 <br />Response to Adequacy Letter of August 1, 2006 <br />6 September 2006 <br />Page 6 <br />Storage of diesel fuel may take place on the permit site, to provide ample supply <br />for both plant facilities and mining equipment. An above-ground fuel tank, if <br />provided, would be subject to tank regulations under the Colorado Division of Oil <br />and Public Safety. A Spill Containment, Control, and Countermeasures Plan, as <br />required by federal regulations and administered by the EPA, would also be <br />completed and maintained on-site to mitigate any impacts to ground or surface <br />water in the event of a spill or leak. Subject to regulation by both these agencies, <br />it is likely that any diesel fuel storage provided on the site would utilize adouble- <br />walled tank and may also include appropriate siting criteria, including possible <br />placement within a lined basin (e.g., enclosure by compacted, impervious <br />earthen berming). Containment of at least one and one-half times the volume of <br />the tank would be provided. Should the operator elect to provide a diesel tank on <br />the site, the applicant commits to forwarding tank specifications and any other <br />containment design to the DMG for incorporation into the M-2006-046 permit as <br />a Technical Revision. <br />Finally, waste concrete may be brought back to the site to be washed and <br />reclaimed as aggregate constituents, or to be hardened and rubblized for <br />recycling as course aggregate. Any recycling system for unused products will be <br />incorporated into aclosed-cycle system for process water. The process water <br />system will include a sedimentation basin to settle and collect particulates for <br />proper disposal off-site. <br />10. Please describe the construction of the cofferdam for the sump pit in <br />Phase 18, including the materials and installation method. <br />Two alternative methods are envisioned for the construction of the cofferdam. <br />Both options begin with the excavation of a basin area at the northern end of the <br />Phase 1B mining area. The slope that will form the "wall" between the <br />clarification basin and the bulk of Phase 1 B mining will be mined to 3:1 slopes. <br />The volumetric capacity of the basin, including freeboard, will be sufficient to <br />handle the maximum dewatering rate during mining, as well as stormwater <br />detention for those disturbed areas of the site with surface runoff. The <br />excavation in this area may involve dredging construction materials below <br />groundwater, but will result (with backfill, if needed) in the establishment of a <br />basin floor elevation that will not expose groundwater and will provide sufficient <br />grade to outlet storm flows to the Colorado River. Once the basin is completed, <br />production mining in Phase 16 will begin on the opposite (south) end of the <br />Phase 16 mining area. <br />In Alternative 1, the cofferdam will be a permanent land bridge between the <br />production mining area and the clarification basin. In this alternative, the <br />northern end of the production mining area will be mined to 3:1 slopes to form an <br />