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CfTY iDF EVERETT STORMWATER MANAGEMENT MANUAL <br /> 1. Maximiu the depth o(the topsoil wherever possible to provide the maximum passible iafiltntion ` � <br /> capaciry and beneficial growth medium. Topsoil depth shall be at least S inches with a minimum <br /> organic content of 10 percent dry weight and pH benvecn 6.0 and 8.0 or matching the pH of the <br /> undisturbed soil. This can be accomplished eiiher by retuming native topsoil ro the site anNor <br /> incorporating organic amendments. Organic ameodments s6ould be incorporated to a miaimum <br /> 8-�nch dept6 except whe:e tree roou or other namral features limit the depth of incorpontion. <br /> Subsoils below the 12-inc6 depth should be scarified at least 2 inches to avoid stratified layers, <br /> where feasible. The decision to either layer lopsoil over a subgrade or incorporate tapsoil into thc <br /> underlying layer may vary depending on the planting specified. <br /> .,. If blended topsoil is imported,then fines should be limited to 25 percent passing through a <br /> 200 sicvc. <br /> 3. The final composition and conswction of t6e soil system will result in a natural selection or <br /> favoring of certain plant species over time. For example, recent practices have s6own that <br /> incoeporation of topsoil may favor grasses,while layering with mildty acidic,high-carbon <br /> amendments may°avor more woody vegetation. <br /> 4. Locate the topsoil stockpile so that it meets specifications and docs not iNedere with work on thc <br /> site. It may be possiblc to locate more than one pile in proximity to areas where topsoil will be <br /> uscd. <br /> 5. Allow sufficicnt time in scheduling far topsoil to be spread prior to seeding,sodding,or planting. <br /> 6. Care must be taken not to apply to subsoil if the two soils have wn!rasting textures. Sandy <br /> topsoil over clayey subsoil is a particularly poor combination,as watercreeps along thejunction <br /> bctween the soil layers and causes the topsoil to slough. <br /> 7. If topsoil and subsoil are not propetly bonded, water will nol infiltrate the soil prof le evcnly and ' <br /> it will be difficult to establish vegetation. The best mc[hod to prevent a lack of banding is to <br /> actually work thc topsoil into the layer below for a depth o[at least 6 inches. <br /> 8. Ripping or reshucturing the sub�ade may also provide additional beoeSts regatding t6e overall <br /> infiltration and interflow dynamics of the soil system. <br /> 9. Field exploration of the site shall be mede to detertnine if there is surfacc soil of sufficiem <br /> quantity and quality tojustify shipping. Topsoil shall bc friable and loamy(loam,sandy loam, <br /> silt loam,sandy clay loam, and clay loam). Areas of natural groundwater rccharge should be <br /> avoided. <br /> ]0. Stripping shall be confined to the immcdiate conswction arca. A 4-to 6-inch stripping dcpth is <br /> common,but dept6 may vary dependiug on the particular soil. All sudace nmoftcnnrtol <br /> struchues shall be in place prior to stripping. <br /> Stockpiling of ropsoil shall occur in Ihc following manncr. <br /> 1. Side slopcs of the stockpile shall not excccd 2:1. <br /> 2. M interceptor dike with gravel ouUet and silt fence shall surround aIl topsoil stockpiles between <br /> October 1 and April 30. Bchveen May l and Septembcr 30,an interceptor dike with gravel outlet <br /> and silt fence shall be installed if the stockpile will remain in place (or a longer period of time <br /> than activc construction grading. <br /> 3. Erosion control seeding or covering with clear plastic or other mulching materials of stockpiles <br /> shall be complelcd within 2 days(October l through April 30)or 7 days(May I through <br /> September 30)of the formatioo of the stockpile. Nativc topsoil stockpiles shall not be wvered <br /> with plastic. <br /> Volume!I—Construction Stormwafer Pollution Pravention <br /> 3•21 <br />