220 OLYMPIC BLVD VA OUTPATIENT CLINIC 2023-02-09

1 intercepting surface drainage to retain their diversion shape and capability. I . Use temporary erosion and sediment control measures or re-vegetate as necessary to pre- vent erosion during ditch reshaping. . Do not leave ditch cleanings on the roadway surfaces.Sweep, collect, and dispose of dirt and I debris remaining on the pavement at the completion of ditch cleaning operations as described below: Consider screening roadside ditch cleanings, not contaminated by spills or other releases and not associated with a stormwater treatment system such as a bioswale,to remove litter.Separate screenings into soil and vegetative matter(leaves,grass, I needles, branches,etc.)categories.Compost or dispose of the vegetative matter in a municipal waste landfill. Consult with the jurisdictional health department to discuss use or disposal options for the soil portion. For more information,see Appendix IV-B: Man- 111 agement of Street Waste Solids and Liquids. Roadside ditch cleanings contaminated by spills or other releases known or suspected to contain dangerous waste must be handled following the Dangerous Waste Regu- lations(Chapter 173 303 WAC). If testing determines materials are not dangerous waste but contaminants are present, consult with the jurisdictional health department I for disposal options. . Examine culverts on a regular basis for scour or sedimentation at the inlet and outlet,and repair as necessary. Give priority to those culverts conveying perennial and/or salmon-bear- I ing streams and culverts near streams in areas of high sediment load,such as those near sub- divisions during construction. Maintain trash racks to avoid damage, blockage,or erosion of culverts. Recommended Treatment BMPs: Install biofiltration swales and filter strips(see V-7 Biofiltration BMPs)to treat roadside runoff wherever practicable and use engineered topsoils wherever necessary to maintain adequate veget- ation.These systems can improve infiltration and stormwater pollutant control upstream of roadside Iditches. S417 BMPs for Maintenance of Stormwater I Drainage and Treatment Systems I Description of Pollutant Sources: Facilities include roadside catch basins on arterials and within residential areas, conveyance systems,detention facilities such asponds and vaults,oil/water sep- arators, P arators, biofilters, settling basins, infiltration systems,and all other types of stormwater treatment sys- tems presented in Volume V. Oil and grease, hydrocarbons,debris, heavy metals,sediments and contaminated water are found in catch basins,oil and water separators, settling basins,etc. Pollutant Control Approach: Provide maintenance and cleaning of debris, sediments,and other Ipollutants from stormwater collection,conveyance,and treatment systems to maintain proper oper- ation. I I 2019 Stormwater Management Manual for Western Washington Volume IV-Chapter 3-Page 516