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EXHIBIT D <br />Mining Plan <br />Genera! <br />The proposed Duckworth property permit boundary will encompass 56.5 acres; mining <br />activities are anticipated to disturb approximately 52 acres. An existing mining operation <br />lies immediately to the south of this property. Currently pastureland lies to the west but is <br />permitting for mining operations, and low-density residences to the north and east. The <br />property is located north of Weld County Road 20 'h, west of Weld County Road 7. <br />The deposit consists of alluvial sand and gravel overlain by topsoil and overburden. The <br />topsoil and overburden layer ranges in depth from 2 to 5 feet with an average thickness of <br />3.6 feet. The depth of topsoil to be stripped is 4" to 6", the depth of overburden varies <br />from 1.5' to 4.5'. The sand and gravel deposit varies in thickness from 13 to 18 feet; the <br />average thickness is 15 Feet. The deposit is underlain by a sandy siltstone. The average <br />depth of excavation will be 20 feet, the maximum depth will not exceed 25 feet.. <br />Overburden volumes have been calculated at 148,000 bank cubic yards and will be used for <br />reclamation. Resource deposit is estimated to be 1,500,000 tons. <br />The groundwater level lies 3 to 6 feet below natural ground level. The deposit is therefore <br />classified as a wet alluvial deposit. However, mining operations will be carried out <br />following dewatering. The sand and gravel is catalogued in the report Sand, Gravel, and <br />Quarry Resources, Colorado Front Range Counties (Colorado Geologic Survey, 1974). <br />Mining Method <br />Dry mining techniques will be used at Duckworth. Initially, a dewatering ditch will be <br />excavated azound the perimeter of the active mining area. Groundwater recovered in the <br />dewatering ditch will be discharged in accordance with Colorado/NPDES discharge permit <br />regulations. <br />Topsoil and overburden will be stripped with scrapers or dozers and placed sepazately in <br />temporary stockpiles within the permit area limits. The topsoil will be segregated and <br />stored separately from the overburden material as required by Rule 3.1.9(1). The topsoil <br />will be placed in berms around the perimeter of the mine cells and will also serve as visual <br />barriers, see Exhibit C. The berms are expected to be approximately 4 feet high and 24 feet <br />wide with 2:1 side slopes. The berms along Idaho Creek will be 12 feet wide to avoid <br />impacts to jurisdictional wetlands. The topsoil stockpiles will be protected from wind and <br />water erosion by vegetative cover, please see the Proposed Seed Mix on page 13. The <br />stockpiles will be broadcast seeded and incorporated into our weed control program. Weed <br />control consists of monthly inspections and, if necessary, chemical treatments in the <br />applicable fall and spring seasons. Topsoil stockpiles that will be in place for less than one <br />year will not be vegetated. <br />The overburden stockpiles will be continuously rotating. Initially the southern portion of <br />Phase I will be stripped and the overburden stockpiled on the northern portion of Phase I. <br />OMG 1!1 Permi! <br />Page 7 of 49 <br />