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r <br />5 <br />Fr <br />22 �IW2A <br />SMA EXE P <br />Introduction <br />The office and boneyard areas at the Seneca II Mine were approved <br />as Small Area Exemptions in Minor Revisions 3 and 11. The three <br />area do not drain to a sedimentation pond. The areas comprise a <br />total of 5.41 acres of disturbance. There are currently <br />approximately 3,300 acres of drainage area that are contained by <br />four sedimentation ponds. The exemption areas represent 5.41 <br />acres of drainage area or 0.18 percent of the total that drains <br />to sediment ponds. <br />A computer model, SEDCAD +, was used for this revision to <br />demonstrate the viability of alternate sediment control methods. <br />The shortcoming of the model is that it was designed to estimate <br />runoff and predict sedimentology for disturbed lands. These <br />area in question are comprised of grass lawns, gravel parking <br />areas, building roofs, and equipment storage areas and are not <br />really adaptable to SEDCAD input parameters. <br />Additional Information - December 2, 1993 <br />The areas listed above were sampled for settleable solids during periods <br />of snowmelt and rainfall. That information is summarized on Table <br />7- 6 -7 -1. The sampling effort was conducted in lieu of silt fence <br />installation (pending sampling results) . Sample results indicate only one <br />location exceeded 0.5 ml /1; this was sample Site E near the office (see <br />Figure 7- 6 -7 -1). Runoff from this area contained sediment from the <br />parking area, which at the time contained mud from the recent rains. <br />Therefore, this may or may not be indicative of normal operations. The <br />Seneca Mine proposes the installation of either silt fencing or straw <br />bales at this location. Information regarding potential silt fence <br />location and SEDCAD runs will remain in the application for future use, if <br />required. <br />NOR 006602 <br />7 -6 -7 -2 Revised 12/02/93 <br />V , <br />