7800 EVERGREEN WAY HYUNDAI O&M Manual 2025-04-28

•ntercepting surface drainage to retain their diversion shape and capability. ▪ Us- emporary erosion and sediment control measures or re-vegetate as necessar, to pre- vent e •sion during ditch reshaping. • Do not lea : ditch cleanings on the roadway surfaces. Sweep, collect, and • spose of dirt and debris remain '• on the pavement at the completion of ditch cleaning op- ations as described below: Consider scree,ing roadside ditch cleanings, not contami .ted by spills or other releases and not - sociated with a stormwater treatme► system such as a bioswale, to remove litter. Separa - screenings into soil and veg- -tive matter(leaves, grass, needles, branches, etc. ategories. Compost or •.spose of the vegetative matter in a municipal waste landfill. C.•sult with thejuris•' tional health department to discuss use or disposal options for the soi •ortion. For •.re information, see Appendix IV-B: Man- a•ement of Street Waste Solids : d Li• •s. Roadside ditch cleanings contami-by spills or other releases known or suspected to contain dangerous waste mus •e ha •led following the Dangerous Waste Regu- lations(Cha•ter 173 303 WA . If testing •:termines materials are not dangerous waste but contaminants ar: •resent, consult h the jurisdictional health department for disposal options. • Examine culverts on a re• • ar basis for scour or sedimentatio at the inlet and outlet, and repair as necessary. G' e priority to those culverts conveying p_ ennial and/or salmon-bear- ing streams and cul •rts near streams in areas of high sediment If Id, such as those near sub- divisions during onstruction. Maintain trash racks to avoid damage, . ockage, or erosion of culverts. Recomme •ed Treatment BMPs: Install bio • ration swales and filter strips(see V-7 Biofiltration BMPs)to treat roadside ru•off where -r practicable and use engineered topsoils wherever necessary to maintain adequa : veget- ation.These systems can improve infiltration and stormwater pollutant control upstream of roa• ide d ches. S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems Description of Pollutant Sources: Facilities include roadside catch basins on arterials and within residential areas, conveyance systems, detention facilities such as ponds and vaults, oil/water sep- 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 pollutants from stormwater collection, conveyance, and treatment systems to maintain proper oper- ation. 2019 Stormwater Management Manual for Western Washington Volume IV-Chapter 3-Page 516