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<br />The Deserado Mine uses degasification boreholes as a method to <br />liberate methane gas from the longwall panels. These holes are <br />located according to coal seam geology and surface locations <br />are often in less than ideal locations for construction of the <br />drill pad. The example shown on the attached drawing shows a <br />worst case location on a steep sidehill. The disturbed area is <br />0.43 acres and has a perimeter berm and ditch surrounding the <br />area and separating it from any undisturbed runoff. <br />To establish a typical example we chose an existing pad site <br />and performed a topographic survey. The area shown and <br />modelled is a worst case scenario and sediment control <br />measures used here are considered adequate for all sites <br />of lesser severity. It is our intent that this example shall <br />apply to all drilling sites including but not limited to <br />degas, dewatering, and exploration. <br />Runoff and sediment modelling was performed using SEDCAD+, <br />Version 3. <br />The following parameters were used within Sedcad to model the <br />pads. <br />• Average acreage: 0.43 acres <br />Soil type: Moyerson D. This is the dominant soil type for mine <br />site. <br />Land use: 2, Tilled bare overland flow. <br />Runoff curve #: 94 Developing area no vegetation. <br />Soil erodibility: .28 as shown for similar construction in <br />permit. <br />Control practice factor: 1.2, for compacted bulldozed scraped <br />across slope. <br />Particle size distribution: Same as shown in permit. <br />Event: 10 year 24 hour event, 1.6" rainfall. <br />While the berm and ditch are adequate to handle these flows <br />they are not adequate to store this event. Flow velocities <br />shown are well below the 6-8 feet per second range. <br />Therefore to control the sediment from these areas the <br />following measures will be taken. <br />1. The disturbed area shall be separated from the surrounding <br />areas undisturbed runoff by means of a berm or diversion <br />ditch. <br />2. The berm will be breached at the low point to prevent <br />an impoundment from being formed and a 5' porous rock outlet <br />structure will be installed to control the sediment. The rock <br />outlet structures will be inspected periodically to ensure <br />• that they are in good repair and are not clogged with <br />sediment. The discharge from these structures will be sampled <br />and tested whenever a 10 year event is suspected. <br />