220 OLYMPIC BLVD VA OUTPATIENT CLINIC 2023-02-09

I Applicable Operational BMPs: Maintain stormwater treatment facilities per the operations and maintenance(O&M)procedures presented in Appendix V-A: BMP Maintenance Tables in addition to the following BMPs: . Inspect and dean treatment BMPs,conveyance systems,and catch basins as needed, and determine necessary O&M improvements. I . Promptly repair any deterioration threatening the structural integrity of stormwater facilities. These include replacement of dean-out gates,catch basin lids, and rock in emergency spillI - ways. . Ensure adequacy of storm sewer capacities and prevent heavy sediment discharges to the sewer system. . Regularly remove debris and sludge from BMPs used for peak-rate control,treatment,etc. and discharge to a sanitary sewer if approved by the sewer authority,or truck to an appro- priate local or state government approved disposal site. • Clean catch basins when the depth of deposits reaches 60 percent of the sump depth asI measured from the bottom of basin to the invert of the lowest pipe into or out of the basin. However, in no case should there be less than six inches clearance from the debris surface to the invert of the lowest pipe. Some catch basins(for example,WSDOT's Catch Basin Type 1L (WSDOT,2011))may have as little as 12 inches sediment storage below the invert. These catch basins need frequent inspection and cleaning to prevent scouring.Where these catch basins are part of a stormwater collection and treatment system,the system owner/operator I may choose to concentrate maintenance efforts on downstream control devices as part of a systems approach. . Properly dispose of all solids, polluted material,and stagnant water collected through system cleaning. Do not decant water back into the drainage system from eductor trucks or vacuum equipment since there may be residual contaminants in the cleaning equipment. Do not jet material downstream into the public drainage system. • Clean woody debris in a catch basin as frequently as needed to ensure proper operation of the catch basin. I . Post warning signs; "Dump No Waste-Drains to Ground Water,""Streams,""Lakes,"or emboss on or adjacent to all storm drain inlets where possible. I . Disposal of sediments and liquids from the catch basins must comply with Appendix IV-B: Management of Street Waste Solids and Liquids. I S421 BMPs for Parking and Storage of Vehicles and Equipment 111 Description of Pollutant Sources: Public and commercial parking lots such as retail store,fleet vehicle(including rent-a-car lots and car dealerships),equipment sale and rental parking lots,and I 2019 Stormwater Management Manual for Western Washington Volume IV-Chapter 3-Page 517