220 OLYMPIC BLVD VA OUTPATIENT CLINIC 2023-02-09

Pollutant Control Approach: Maintain appropriate vegetation to control erosion and the dis- charge of stormwater pollutants. Prevent debris contamination of stormwater.Where practicable, I I I I I I I I II I I I grow plant species appropriate for the site,or adjust the soil properties of the site to grow desired plant species. Applicable BMPs: . Install engineered soil/landscape systems to improve the infiltration and regulation of storm- water in landscaped areas. . Select the right plants for the planting location based on proposed use, available main- tenance,soil conditions,sun exposure,water availability, height, sight factors,and space avail- able. . Ensure that plants selected for planting are not on the noxious weed list. For example, but- terfly bush often gets planted as an ornamental but is actually on the noxious weed list. The Washington State Noxious Weed List can be found at the following webpage: https://www.nwcb.wa.gov/printable-noxious-weed-list . Do not dispose of collected vegetation into waterways or storm sewer systems. . Do not blow vegetation or other debris into the drainage system. . Dispose of collected vegetation such as grass clippings, leaves,sticks by composting or recyc- ling. . Remove, bag,and dispose of class A& B noxious weeds in the garbage immediately. . Do not compost noxious weeds as it may lead to spreading through seed or fragment if the composting process is not hot enough. I . Use manual and/or mechanical methods of vegetation removal(pincer-type weeding tools, flame weeders,or hot water weeders as appropriate)rather than applying herbicides,where practical. . Use at least an eight-inch"topsoil"layer with at least 8 percent organic matter to provide a suf- ficient vegetation-growing medium. Organic matter is the least water-soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually,and this release corresponds closely to the plant growth cycle. Return natural plant debris and mulch to the soil,to continue recycling nutrients indef- initely. I . Select the appropriate turfgrass mixture for the climate and soil type. Certain tall fescues and rye grasses resist insect attack because the symbiotic endo- phytic fungi found naturally in their tissues repel or kill common leaf and stem-eating lawn insects. 2019 Stormwater Management Manual for Western Washington Volume IV-Chapter 4-Page 524