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I <br /> Drainage Report <br /> Boeing Everett-E-6 Parking Lot Expansion July 16,2013 <br /> 4.3 Element#3—Control Flow Rates <br /> During construction, flow rates will be controlled through the use of straw wattles and, if <br /> necessary, temporary sediment traps to collect excessive site runoff. Applicable BMPs may <br /> include: <br /> • BMP C240: Sediment Trap <br /> 4.4 Element#4—Install Sediment Controls <br /> All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal <br /> ' BMP before leaving the construction site. Sediment barriers and other BMPs intended to trap <br /> sediment onsite shall be constructed as one of the first steps in grading. The specific BMPs used <br /> for controlling sediment on this project include: <br /> • BMP C233: Silt Fence <br /> • BMP C235: Straw Wattles <br /> 4.5 Element#5—Stabilize Soils <br /> Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and <br /> when possible, be located away from storm drain inlets, waterways and drainage channels. The <br /> contractor shall install bedding materials, structures, or pipelines and re-stabilize so that: <br /> From October 1 through April 30 no soils shall remain exposed and unworked for <br /> more than 2 days and <br /> - From May 1 to September 30, no soils shall remain exposed and unworked for more <br /> than 7 days. <br /> Specific BMPs used for stabilizing soils on this project include: <br /> 1 • BMP C 123: Plastic Covering <br /> • BMP C140: Dust Control <br /> 4.6 Element#6—Protect Slopes <br /> Onsite soil stockpiles shall be protected with sediment trapping measures in a manner that <br /> minimizes erosion. The following specific BMPs may be used to protect slopes for this project: <br /> • BMP C123: Plastic Covering <br /> I <br /> 4.7 Element#7—Protect Drain Inlets <br /> All storm drain inlets made operable during construction shall be protected to prevent unfiltered <br /> water from entering the drainage conveyance system. However, the first priority is to keep all <br /> access roads clean of sediment and prevent street wash water from entering storm drains until <br /> treatment can be provided. Sediment and street wash water shall not be allowed to enter storm <br /> drains without prior and adequate treatment. Inlets should be inspected weekly at a minimum and <br /> daily during storm events. Inlet protection devices should be cleaned or removed and replaced <br /> I <br /> 20130715_Drainage Report_Boeing Everett_Gate E-6 Parking Lot.doc Page 10 <br /> I <br />