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Phase III includes the mining of Pond 3. The Huett Ditch will have previously been relocated <br />and the shiny wall for the final reservoir should be complete. Overburden stripped during the <br />initial stages of Phase III will be used to finish backfilling mining azea 1. Excavation of Pond 3 <br />will continue while simultaneously creating side slopes for the final reservoir. Phase III will also <br />likely include installation of inlet and outlet structures for all of the reservoirs. <br />Mining Methods <br />The deposit will be wet and/or dry mined. Dry mining will occur through the installation of <br />slurry walls with the use of dewatering trenches and pumps. It is anticipated that slurry walls <br />will be constructed azound the perimeter of Ponds 1, 2, and 3. Design specifications for the <br />slurry walls and quality control procedures used during construction will ensure that the <br />reservoirs meet State Engineer's Office (SEO) performance standazds. Specific specifications <br />and quality control procedures will be provided to the Division for review, in the form of a <br />technical revision, prior to construction of the slurry walls. Dewatering trenches and pumps will <br />be used to dewater the deposit enclosed within the slurry walls prior to mining below the water <br />table. The ponds may also be mined prior to complete installation of the shiny walls through the <br />use of dewatering trenches and pumps. Dewatering trenches will be excavated azound the <br />perimeter of each pond prior to mining and pumps will be used to remove the water that drains <br />from the deposit and surrounding alluvium into the trench. If necessary, water from the trenches <br />will be circulated through a settling basin to meet applicable Colorado Discharge Permit System <br />requirements prior to it being dischazged to the Huett Ditch or South Platte River. <br />Mining azeas 1, 2, and 3 may also be dry mined using dewatering trenches and pumps, as <br />described above, or may be wet mined. Slurry walls will not be installed azound these mining <br />azeas. If the mining azeas are wet mined, a dragline or dredge will be used to excavate the <br />aggregate material below the groundwater table. The material wet mined from the pit will be <br />stockpiled and allowed to dewater prior to transporting the material for processing. Stockpile <br />placement and ground slopes will allow the water draining from the aggregate material to reenter <br />the pit lake. <br />The aggregate material will be recovered using equipment and facilities typical for sand and <br />gravel mining operations. The equipment and facilities may include, but aze not limited to the <br />following: <br />Processing_Eq_uipment <br />Portable, temporary processing equipment on an as needed basis for screening, crushing, <br />and washing. <br />Earth Moving_ uiument <br />Dozers, loaders, scrapers, excavators, dragline, dredge, and compactors will be used for <br />mining and earth moving operations. Field conveyors will be used as needed for mining <br />operations. <br />Wanen6erg rakes <br />DMG 112 Permit <br />Page 6 <br />