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Firefox <br />about:blank <br />Glossary <br />Definitions are arranged alphabetically by term. Fora complete reference, please see <br />the Stormwater Management Manual for Western Washington (SWMMWW): <br />fortrewvva-jav/ /euha l&rmitsflamMl95WMMWW/2019SWMMYVWhtm <br />Best ManagementPractlee 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 <br />The densification, settlement, or packing of soil in such a way that permeability of <br />the soft is reduced. <br />Compost <br />Organic material that has undergone biological degradation and transformation <br />under controfled conditions designed to promoteaerobic decomposition ata solid <br />waste facility in compliance with the requirements of Chapter 173-350 WAC, or <br />blosolids composted in compliancewith Chapter 173-308 WAC. Compostingis a <br />form of organic material recycling. <br />Critical Area <br />Ataminimum,areaswhich includewetlands, areas with acriticalrechargingeffect <br />on aquifers used for potable water, fish and wildlife habitat conservation areas, <br />frequentlyflooded areas, geologically hazardous areas, Including unstable slopes, <br />and associated areas and ecosystems. <br />Dispersion <br />Release of surface and stormwater runoff such that the flow spreads over a wide <br />area and is located so as not to allow flow to concentrate anywhere upstream of a <br />drainage channel with erodible underlying granular soils. <br />Hard Surface <br />An impervious surface, a permeable pavement, or a vegetated roof. <br />Impervious Surface <br />Anon-vegetatedsurfaceareawhicheitherpreventsorretardstheentryofwaterinto <br />the soil mantle as under natural conditions prior to development. A non -vegetated <br />surface area which causes water to run offthe surface In greater quantities or atan <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 or storage 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 Evewft Public Works <br />Sma#PrgectSformwaterSitePlan Report April 2021 <br />22 of 23 <br />6/8/2021, 10:18 AM <br />