4620 SEAHURST AVE 2020-05-20 - Laserfiche WebLink

March 7, 2011 Mr. Paul Thompson/Kolbear, Inc. L&A Job No. 11-001 • Page 7 TEMPORARY DRAINAGE AND EROSION CONTROL The onsite surficial topsoil and weathered soil contain a high percentage of fines which are sensitive to moisture and can be easily disturbed by construction traffic. A layer of clean,2-to-4- inch quarry spalls should be placed over areas of frequent traffic, such as the entrance to the site, as required,to protect the subgrade soils from disturbance by construction traffic. A silt fence should be installed along the downhill side of construction area to minimize transport of sediment onto neighboring properties or the streets. The bottom of the filter cloth of the silt fences should be anchored in a trench filled with onsite soil. Ditches or interceptor trench drains should be installed on the uphill side of construction area, as required, to intercept and drain away storm runoff and near-surface groundwater seepage, if any. Water captured by such ditches or interceptor trench drains should be discharged into a nearby storm inlet or dispersed onto a well-vegetated area with perforated PVC dispersion pipes. The dispersion pipes should sufficiently long and set horizontal such that water flowing out of the pipes would be at a low velocity not to cause erosion problem. The storm inlet, if into which stormwater is to be discharged, should be covered with a filter sock to prevent sediment from entering the storm sewer system. The filter sock should be cleaned frequently during construction to prevent clogging,and should be removed after completion of construction. Spoil soils should be hauled off of the site as soon as possible. Spoil soils and imported structural fill material to be stored on site should be located in areas where the ground surface is no steeper than 15% grade, and should covered with plastic tarps securely weighted down with sandbags. LIU & ASSOCIATES, INC.