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1 <br /> jSection IV: Construction Stormwater Pollution Prevention Plan <br /> All erosion and sediment control measures shall be governed by the requirements of the City of <br /> Everett. A temporary erosion and sedimentation control plan has been prepared to assist the <br /> contractor in complying with these requirements. The Erosion and Sediment Control (ESC) plan is <br /> included with the construction plans. <br /> Element 1: Mark Clearing Limits <br /> Prior to beginning land disturbing activities, including clearing and grading, all clearing <br /> limits, sensitive areas and their buffers, and trees that are to be preserved within the <br /> construction area shall be clearly marked, both in the field and on the plans, to prevent <br /> damage and offsite impacts. <br /> • Plastic, metal, or stake wire fence may be used to mark the clearing limits. <br /> The duff layer, native top soil, and natural vegetation shall be retained in an undisturbed <br /> state to the maximum extent practicable. If it is not practicable to retain the duff layer in <br /> place, it should be stockpiled on-site, covered to prevent erosion, and replaced <br /> immediately upon completion of the ground disturbing activities. <br /> Element 2: Establish Construction Access <br /> • Construction vehicle access and exit shall be located in the southeast corner of the site <br /> from the existing development on Lot 3A. <br /> t • Access points shall be stabilized with a pad of quarry spalls or crushed rock prior to traffic <br /> leaving the construction site to minimize the tracking of sediment onto public roads. <br /> • Wheel wash or tire baths should be located on-site, if necessary. <br /> • If sediment is tracked off site, public roads shall be cleaned thoroughly at the end of each <br /> day, or more frequently during wet weather,if necessary to prevent sediment from entering <br /> waters of the state. Sediment shall be removed from roads by shoveling or pickup sweeping <br /> and shall be transported to a controlled sediment disposal area. Street washing will be <br /> allowed only after sediment is removed in this manner. <br /> • Street wash wastewater shall be controlled by pumping back onsite, or otherwise be <br /> prevented from discharging into systems tributary to state surface waters. <br /> 1 Element 3: Control Flow Rates <br /> • A temporary sediment pond is proposed in the western portion of the site to control flow <br /> rates for the Powdermill Gulch Creek basin during construction. <br /> ' Q = CiA <br /> C = 0.81 (per calculation in Table 3B in Section VIII) <br /> ' i = WI" = 6.31/(6.77') = 2.10 in/hr <br /> m=6.31 (10-year) <br /> n=0.575 (10-year) <br /> T=6.77 min (see calculations in Conveyance Analysis Section) <br /> A = 1.37 (per calculation in Table 3B in Section VIII) <br /> Q 1 0-year = 0.81 x 2.10 x 1.37 = 2.33 cfs <br /> Sediment pond surface area at top of riser=2,083 sf x 2.33 cfs = 4,854 sf <br /> I6/16/2011 Stormwater Site Plan Page 11 <br />