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Mining activities proposed herein would not significantly impact equipment used or frequency of <br /> use. Trucks would continue to travel on the existing roads (and proposed roads) at a rate of <br /> approximately 80 to 100 trucks per day, typically 5 days per week. When not in use, trucks would <br /> be parked in existing parking areas near the existing Mine Office shown Qn Drawing O1. <br /> 2.8 Soil, Waste, and Mineable Material <br /> Based on field observations and previous pemniba` there is no true 'lopSOi|~ at the Mine. |nhact <br /> (native)growth medium i8sparse and consists mainly of weathered gypsum (gypeihe)and residual <br /> volcanic ash. Previous permits and investigations reported depths of volcanic ash ranging in <br /> thickness from 3 inches to 2 feet (isolated pockets as deep as 2 feet are typically found in dry <br /> creek beda)� this material would be salvaged along with other growth medium during East Pit <br /> clearing and grubbing activities and stockpiled with maximum side slopes mf2H:1Vin the growth <br /> medium stockpile shown on Drawing 00 for future use as growth medium during reclamation <br /> activities. VVhena salvaged growth nnodiurn contains biological soil crust mnater|a|, the stockpiled <br /> depth would be limited to a depth of4 feet to promote continued algae,fungi, and lichen formation <br /> and assist in stabilizing the growth medium stockpile Surface. If stockpiled growth medium is <br /> dormant more than O rnOnths, the stockpile will be revegetated using an approved seed mixture <br /> to stabilize surface material and inhibit weed growth. <br /> Overburden was estimated for the East Pit only. No overburden is expected to be encountered in <br /> the Upper Pit area, as the pit is being actively mined and overburden was removed in the early <br /> stages of mining. Non-economic material encountered during mining is classified as intnaburden <br /> (waste). The East Pit was anticipated to have a similar gypsum-to'intnaburden ratio as the <br /> operational Upper Pit, assuming 55`Y6 of the mna1eno| encountered during mining (by weight) is <br /> usable gypsum. Where the proposed East Pit depth exceeds the operational Upper Pit depth, the <br /> gypsum-to-intraburdgn ratio was estimated assuming only 40Y& of the pit material (by weight) is <br /> usable gypsum. AGthe Upper Pit and East Pit are developed, American Gypsum would propose <br /> additional drilling to refine these estimates and may modify the overall pit depth or footprint if drill <br /> data or continued mining activities do not produce usable gypsum. Material eSUnn8teS are <br /> Sunnrnerizad in Table 2.3. The conceptual growth medium stockpile location is shown on <br /> Drawings O0 and O8. <br /> zu <br />