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Horizon Elementary School — Classroom Portable Installation <br /> INConstruction SWPPP Narrative <br /> May 10, 2019 <br /> engineering p c <br /> HORIZON ELEMENTARY SCHOOL <br /> CLASSROOM PORTABLE INSTALLATION <br /> CONSTRUCTION SWPPP NARRATIVE <br /> MAY 10,2019 <br /> The following Preliminary Construction Storm Water Pollution Prevention Plan(CSWPPP) <br /> Narrative is for the installation of a double classroom portable structure at Horizon Elementary <br /> School located at 222 W Casino Road in Everett, Washington(parcel#28041300102100). The <br /> narrative supplements the Temporary Erosion and Sediment Control(TESC)plan. This narrative <br /> and the drawings address the requirements of section 2.3.1 of Volume II of the 2010 City of <br /> Everett Stormwater Management Manual. Refer to the TESC plans(Sheet CI.0)and TESC <br /> details (Sheet C3.0)for more information regarding any erosion or sedimentation control <br /> measures involved in this project. <br /> I . CONSTRUCTION STORMWATER POLLUTION PREVENTION ELEMENTS <br /> 1) Mark Clearing Limits: Clearing limits will be delineated with a"limit of work" line on <br /> the TESC and Site Demolition plan. Perimeter erosion control components, such as silt <br /> fence will define clearing limits. The actual limits of clearing may be smaller than the limit <br /> of work,but this identifies the maximum extent of the clearing limits. Areas impacted that <br /> are not anticipated to be covered with final measures shall be stabilized using approved <br /> TESC methods. <br /> 2) Establish Construction Access: The project area will be accessed from 85th P1 SW, <br /> through the existing gravel pathway along the western portion of the site and through the <br /> sand field to the southwest. If existing pavement and sand field surfacing is inadequate to <br /> support construction vehicles, a temporary quarry spall construction access(BMP C105) <br /> may be installed. The Contractor shall provide wheel wash(BMP CI06) if necessary. <br /> 3) Control Flow Rates: An increase in the velocity or peak volumetric flow rates that <br /> would result in soil erosion is not anticipated for the project. If necessary, an <br /> appropriately sized sediment trap or sediment tank per BMP C249 may be installed. <br /> 4) Install Sediment Controls: DOE approved BMPs for sediment controls are shown on <br /> the TESC plan. Sediment will be controlled using silt fences(BMP C233), and storm <br /> drain inlet protection(BMP C220). <br /> 5) Stabilize Soils: The project is expected to be completed during the dry season,which is <br /> defined as May 1 to September 30. During this period cover measures must be installed <br /> to protect disturbed areas that will remain unworked for seven days or more. By October <br /> 8, seed or repair sand field surfacing that will remain unworked from October 1 through <br /> April 30. Mulch all seeded areas. Cover BMPs including, but not limited to: C101, <br /> Preserving Natural Vegetation; C121,Mulching; C123,Plastic Covering; C130 Surface <br /> roughening; C140, Dust Control; and T5.13 Post Construction Soil Amendment will be <br /> used to stabilize onsite soils during construction. See Erosion and Sediment Control <br /> Notes on the plans in Appendix A. In the event that work is extended into the wet <br /> season, October 1 through April 30,the site must be stabilized and no soils will be <br /> allowed to remain unstabilized for more than 2 days. <br /> Page 1 <br />