2002-12-12_REVISION - M2001085 (7)

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During Phase 5, which is expected to require twenty four months for completion, mining will continue in Area 3. Excavation walls will be maintained at a minimum slope of 2 to 1. Slopes in .Area 2 will be backfilled to achieve reclaimed slopes of 3 to 1, and the clay liner will be completed on top of the slurry wall. Backfilling of excavation walls and lining of reclaimed slopes will continue into Area 3, as mining nears completion. When mining is completed, processing equipment and utilities will be removed. Completion of Phase 5 is projected at approximately five years after the mining operation is initiated. The Applicant estimates that approximately 110,000 cubic yards of material will be necessary for backfilling to achieve 3 to 1 slopes below the top of the slurry wall. Another 30,000 yards of claystone material will be necessary to create a compacted clay cap and liner above the slurry wall. Mining Methods The Applicant will use only dry mining methods. Scrapers and front-end loaders will be used for excavation. Sand and gravel resources will be loaded directly into haul trucks for transport from the site; or a field conveyor system will convey material to the processing equipment. Water Diversions and Impoundments During Phase 2 activity, a shallow rinse water lagoon will be excavated adjacent to the processing equipment. Collection of rinse water in this impoundment will prevent its drainage to the perimeter of the site, where the slurry wall will be installed. Although the Operator will be prepared to recycle rinse water, collected during Phase 2 operations, much of the small volume of rinse water generated during this period will likely pass through the sump to groundwater, until settled fines seal the lagoon. Drainage trenches from the processing plant to the rinse water lagoon will be excavated and maintained, as necessary. This lagoon, for the collection and recycle of rinse waters, will be maintained until the completion of all mining activity. Fines recovered from the rinse water lagoon will be used as backfill to achieve final, reclaimed slopes of 3 to 1. Estimating five percent waste from washing operations, up to 100,000 cubic yards of settled fines may be available for backfill. In Phase 3, after completion of the soil-bentonite slurry wall, a dewatering sump will be excavated towards the northern portion of the mining area. Groundwater, isolated within the mining area will be discharged to the adjacent pond of the Henderson Water Ski Club. A CPDES permit to discharge and a formal agreement with the Ski Club will be obtained prior to any discharge from the mine site. Resources to be Recovered In July 2002, nine, equally spaced soil borings were taken from the proposed mining area. Analysis of these borings showed the site to have three to six feet of native clay Application to Amend -9- 124th Estates Partners DMG 112 Reclamation Permit No. M-2001-085 124th Estates Sand and Gravel Mine Prepared by Scott Keen, December 2002 Henderson, Colorado