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6.4.4 Exhibit D -Mining Plan <br />• of WCR 3'/< . Mining will occur at the site over the course of approximately 6 <br />years. The mining of the west pit will occur in two separate and distinct areas; in <br />the south portion of the west pit and then in the north portion of the west pit. <br />Mining will begin at the northeast corner of the south portion of the west pit to <br />prepare for the relocation of an Encana gas pipeline that runs through the center <br />of the proposed permitted area. The mining will then proceed north to construct <br />the North Pond. After the north portion of the west pit is completely mined, the <br />operation will move to the southern portion of the west pit. When the southem <br />portion of the west pit has been mined, operations will move to the remaining 10- <br />15 acres of the east pit. <br />6.4.4.3 WATER DIVERSIONS AND IMPOUNDMENTS <br />Dewatering trenches will be dug to facilitate dry mining as shown in Exhibit C - <br />Mining Plan. Groundwater was encountered during soil boring operations at a <br />depth of approximately 7-8 feet. Dewatering trenches will capture groundwater <br />seepage as well as excess precipitation entering the excavation and move it <br />away from working areas. There are no groundwater pumping wells, creeks, or <br />other significant bodies of water in close proximity to the permitted mine area that <br />will be affected by the mining operation. A well permit is currently in place for the <br />existing 111 c operation, which will be amended for the entire project. <br />• 6.4.4.4 SIZE OF AREA TO BE WORKED AT ONE TIME <br />The largest surface area to be worked on at any one time will be approximately <br />15-20 acres. The largest stock~ile that will occur at any one time will be no more <br />than approximately 100,000 yd . <br />6.4.4.5 NATURE OF DEPOSIT <br />Most of the site is overlain with a layer of silty sand (SM). This layer averages <br />between 6 and 7-feet thick but appears in the soil borings in thickness ranging <br />from near zero to approximately 11-feet. Underlying this layer of silty sand is a <br />layer of inorganic clay (CL). This layer averages approximately 4-5-feet thick, but <br />is not found in some areas of the site and in others can be found to be as much <br />as 13-feet thick. The overburden is composed of a thin layer (0.5 ft) of loam <br />underlain by silty and clayey sand to sandy and silty clay. The sand and gravel <br />deposit (GW) occurs at an average thickness of 12.5 ft. The thickness of the <br />sand and gravel deposit ranges from a low end of just under 5-feet thick to a high <br />end of roughly 20-feet. <br />6.4.4.6 UNDERLYING STRATUM <br />Underneath the sand and gravel lies bedrock composed of weathered shale and <br />sandstone (Foxhills) <br />I• <br />File Pit 112 DMG Permit Application <br />Page 3 of 27 <br />