2012-03-12_PERMIT FILE - M2011028

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area, reclamation will be initiated as soon as possible. Up to an additional 2 acres could be disturbed along a one mile long gravel access road into the operation area. Other than future paving of the permanent access road, no significant parts of this project area is, or will be, impervious. 3.3.5 Soil Types and Estimated Runoff Coefficient The pre- mining soils are generally described as clay loam to gravelly -sandy loam. These soils are: Farfa clay loam, 1 to 3 percent slopes; Farfa clay loam, 3 to 8 percent slopes; Ustic Torriorthents - Ustollic Haplargids complex, 12 to 60 percent slopes. Generally, the mesa top is covered with the two Falfa loam soils which are eolian material deposited on glacial outwash debris. Their potential for erosion is moderate. The steeper slopes are generally covered with the Ustic /Ustollic soils and also generally cover the glacial outwash materials along the edges of the mesa, and the hazard of erosion is high. The estimated runoff coefficient before development and mining was 0.10 to 0.30. The estimated post- mining runoff coefficient will be 0.18 to 0.22. 3.3.6 Existing Vegetation Existing vegetation on the proposed pit area consists mainly of sagebrush, various native grasses, serviceberry, oak, pinyon trees, juniper trees, and various weeds. The reclaimed area to the north is covered with wheat grass, fescue, and other native grasses. 3.3.7 Location and Description of Potential Pollutant Sources Following are potential pollutant sources that may have an impact on stormwater quality: • Ground disturbing activities: Ground surface disturbing activities could take place anywhere within the property boundaries shown on the site map. • Sand and gravel processing: Mining, transporting, crushing, washing, and sorting of materials. • Equipment or vehicle washing: Infrequently, concrete delivery equipment will be washed out at the designated washout location, along with associated concrete finishing equipment and tools. • Chemical and other material storage: No extraordinary chemicals, etc. will be stored within the operation area. Chemicals associated with mining and processing (such as flocculants and dust palliatives), equipment maintenance (paints and cleaning agents), and petroleum based products (lubricants and solvents) will be stored under protective cover and within appropriate containment. • Vehicle and equipment maintenance and fueling: o Fueling operations of mining and processing equipment will normally take place in the property area, except for equipment that can easily return to offsite service stations each day, such as pickups, vans and Animas Glacier SWMP February 2012 p. 4