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Glossary <br />Definitions are arranged alphabetically by term. For a complete reference, please see <br />the Stormwater Management Manual for Western Washington (SWMMWW): <br />fortress.wa.govlecylersharetw-q/Permits/Flare/2019SWMtn8nM/2019SWMtn8nM.htm <br />Best Management Practice The schedules of activities, prohibitions of practices, maintenance procedures, <br />(BMP) and structural and/or managerial practices, that when used singly or in <br />combination, prevent or reduce the release of pollutants and other adverse <br />impacts to waters of Washington State. <br />Compaction The densification, settlement, or packing of soil in such away that permeability of <br />the soil is reduced. <br />Compost Organic material that has undergone biological degradation and transformation <br />under controlled conditions designed to promote aerobic decomposition at a solid <br />waste facility in compliance with the requirements of Chapter 173-350 WAC, or <br />biosolids composted in compliance with Chapter 173-308 WAC. Composting is a <br />form of organic material recycling. <br />Critical Area Ataminimum,areaswhichincludewetlands,areaswithacriticalrechargingeffect <br />on aquifers used for potable water, fish andwildlife habitatconservation areas, <br />frequentlyflooded areas, geologicallyhazardous areas, including unstable slopes, <br />and associated areas and ecosystems. <br />Dispersion Release of surface and stormwater runoff such that the flow spreads over a wide <br />area and is located so as not to allowflow to concentrate anywhere upstream of <br />drainage channel with erodible underlying granular soils. <br />Hard Surface An impervious surface, a permeable pavement, or a vegetated roof. <br />Impervious Surface Anon-vegetatedsurfaceareawhicheitherpreventsorretardstheentryofwaterinto <br />the soil mantle as under natural conditions prior to development A non -vegetated <br />surface area which causes water to run off the surface in greater quantities or at an <br />increased rate of flow from the flow present under natural conditions prior to <br />development Common impervious surfaces include, but are not limited to, roof <br />tops, walkways, patios, driveways, parking lots orstorage areas, concrete or asphalt <br />paving, gravel roads, packed earthen materials, and oiled, macadam or other <br />surfaces which similarly impede the natural infiltration of stormwater. Open, <br />uncovered retention/ detention facilities shall not be considered as impervious <br />surfaces for the purposes of determining whether the thresholds for application of <br />Minimum Requirements are exceeded. Open, uncovered retention/detention <br />facilities shall be considered impervious surfaces for purposes of runoff modeling. <br />City of Everett Public Works <br />Small ProjectStormwaterSitePlanReport September 2022 <br />