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• During construction of RP-2 topsoil was stockpiled across the <br />eastern perimeter road near the bottom of RP-1. Potential sediment <br />run-off from this pile was considered inconsequential and therefore <br />not modelled for the permit. <br />Sediment control for this pile consisted of a perimeter berm <br />enclosing a small sump. To bring the current permit up to date, a <br />Small Area Exemption sediment demonstration has been conducted for <br />a this topsoil pile. <br />Runoff and sediment modelling was done using SEDCAD +, version 3. <br />The topsoil pile was modelled so as to represent its current <br />condition. The topsoil pile in question was constructed and seeded <br />. more than eight years ago. The pile has a well established growth <br />of a western wheatgrass mixture covering it in its entirety. No <br />rills, gullies or other detrimental erosional effects have been <br />noted on the pile. <br />The following parameters were used within SEDCAD to model the <br />piles: <br />Acreage: 2.71 ac., 1.53 ac. undisturbed acres included in watershed <br />Soil type: Moyerson D. This is the dominant soil type throughout <br />the construction area as determined with SCS <br />publications. <br />Land use: 5, Nearly bare and unfilled, overland flow. Average flow <br />on this pile is less than 300' in length. <br />Run-off curve #: 89, Permanent rangeland, soil group D, poor <br />• condition. 85 for undisturbed. <br />