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areas during three (3) events in 1993. The sample results indicated only one sample from <br />one location exceeded the receiving stream water quality criterion (0.5 milliliters per liter <br />[ml /1]). Because the sampling results were inconclusive, Seneca Coal Company modeled <br />runoff from the areas using SEDCAD+ (Schwab, 1988) to demonstrate that alternative <br />sediment control methods, if necessary, would successfully control sediment delivery from <br />the SAE and that peak 24 -hour average settleable solid concentrations would be less than the <br />water quality criterion (0.5 ml /1). <br />An additional SAE includes the septic leach field and the associated disturbed area; it is only <br />0.1 acre in area. It has been reseeded (as of 11/16/2012) and will be completely vegetated. <br />A SEDCAD4 demonstration using a 1.0 acre, vegetated pad was used for analysis due to the <br />small size of the area. A demonstration was completed using check dams as a control <br />measure and another using silt fences. The demonstration shows that the alternative <br />sediment control methods will successfully control sediment delivery from the SAE. This <br />demonstration can be used for other vegetated areas less than one acre, if needed, at a future <br />date. Table 2.05.3- E2 -14, Small Area Exemption Summary shows the breakdown of these <br />SEDCAD runs. <br />A solar - powered microwave tower will be erected that will link communication infrastructure with <br />that at Sage Creek. The location is on a high ridge with line of site to both Sage Creek and <br />Twentymile facilities. A SAE is required since the site is outside the currently approved disturbance <br />area. A general demonstration was completed using sediment fence /wattles as a control <br />measure for a 1 -acre graveled pad. The demonstration shows that the alternative sediment <br />control methods will successfully control sediment delivery from the SAE. This <br />demonstration can be used for other graveled areas less than one acre, if needed, at a future <br />date. The total area for the pad will be (20' x 20' or 0.01 acres). <br />TABLE 2.05.3 -E2 -14 <br />Small Area Exemption Summar <br />Peak <br />Inflow <br />Inflow <br />Outflow Concentrations <br />If ASC Installed <br />Area <br />Acres <br />Runoff <br />Concentration <br />i <br />Concentration <br />z <br />24AA <br />24VW (ml /1) <br />Type of ASC <br />(cfs) <br />24AA (mUl) <br />24VW (mUl) <br />nd/1) <br />Old Boneyard <br />2.5 <br />0.76 <br />0.24 <br />0.01 <br />Porous rock check dam <br />New Boneyard <br />0.82 <br />0.76 <br />0.47 <br />0.06 <br />Porous rock check dam <br />(NWF -1) <br />New Boneyard <br />0.83 <br />0.77 <br />0.06 <br />0.0 <br />Porous rock check dam <br />(NWF -2) <br />New Boneyard <br />0.4 <br />0.34 <br />0.31 <br />0.01 <br />Porous rock check dam <br />(SWF) <br />New Boneyard <br />0.70 <br />0.60 <br />0.35 <br />0.01 <br />Porous rock check dam <br />Gate <br />Office Parking <br />1.0 <br />0.36 <br />0.22 <br />0.01 <br />Porous rock check dam <br />Area <br />Generic Vegetated <br />1.0 <br />0.31 <br />5.3 <br />0.0 <br />Silt fence <br />Area <br />Generic Vegetated <br />1.0 <br />0.31 <br />5.3 <br />2.6 <br />Porous rock check dam <br />Area <br />Microwave Tower <br />0.08 <br />1.67 <br />0.0 <br />Perimeter Trench & Silt <br />& Pad <br />.01 <br />Fence/Wattles <br />1) 24AA peak 24 -hour arithmetic average settleable solids concentration <br />2) 24V W peak 24 -hour volume weighted average settleable concentration <br />3) ASC alternative sediment control <br />MR -22 2.05.3 -E2.26 Revised 09/2013 <br />