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<br />(F) Site erosion control. The following criteria (F)(1) through (4) apply only to construction activities that <br />result in stormwater leaving the site. <br /> <br />(1) Channelized runoff from adjacent areas passing through the site shall be diverted around <br />disturbed areas, if practical. Otherwise, the channel shall be protected as described below. <br />Sheetflow runoff from adjacent areas greater than 10,000 square feet in area shall also be <br />diverted around disturbed areas, unless shown to have resulted runoff rates of less than 0.5 <br />feet/second across the disturbed area for the 1-year storage. Diverted runoff shall be conveyed in <br />a manner that will not cause erosion, scour or flooding of the conveyance at receiving channels. <br /> <br />(2) All activities on the site shall be conducted in a logical sequence to minimize the area of bare soil <br />exposed at any one time. <br /> <br />(3) Runoff from the entire disturbed area on the site shall be controlled by meeting either divisions <br />(a) and (b) or (a) and (c). <br /> <br />(a) All exposed soil areas with a continuous positive slope within 200 lineal feet of a surface <br />water must have temporary erosion protection or permanent cover for the exposed soil <br />areas year-round, according to the following table of slopes and time frames: <br /> <br />Type of Slope Time <br />Steeper than 3:1 7 days <br />10:1 to 3:1 14 days <br />Flatter than 10:1 21 days <br /> <br />(b) For sites with more than ten acres disturbed at one time, or if a channel originates in the <br />disturbed area, one or more temporary or permanent sedimentation basins shall be <br />constructed. Each sedimentation basin shall have a surface area of at least one percent of <br />the area draining to the basin and at least three feet of depth and constructed in <br />accordance with accepted design specifications. Sediment shall be removed to maintain a <br />depth of three feet. The basin discharge rate shall also be sufficiently low as to not cause <br />erosion, scour or flooding along the discharge channel or the receiving water. <br /> <br />(c) For sites with less than ten acres disturbed at one time, silt fences or equivalent control <br />measures shall be placed along all side slopes and downslope sides of the site. If a <br />channel or area of concentrated runoff passes through the site, silt fences shall be placed <br />along the channel edges to reduce sediment reaching the channel. The use of silt fences <br />or equivalent control measures must include a maintenance and inspection schedule. <br /> <br />(4) Any soil or dirt storage piles containing more than ten cubic yards of material should not be <br />located with a downslide drainage length of less than 25 feet from the toe of the pile to a <br />roadway or drainage channel. If remaining for more than seven days, they shall be stabilized by <br />mulching vegetative cover, tarps or other means. Erosion from piles which will be in existence <br />for less than seven days shall be controlled by placing straw bales or silt fence barriers around <br />408 |Page <br /> <br />