1304 80TH ST SW EVERETT SCHOOL DISTRICT 2018-01-02 MF Import

11. The construction plans must be designed from a site survey performed by a licensed State of Washington land surveyor. 12. All exposed ground must be reseeded within 30 days of the completion of construction if reseeding is not practical due to weather or seasonal problems, the ground must be cove t with mulch as directed by the City Engineer. 13. Temporary erosion control measures for construction activity must be operational prior to commencement of any clearing or earthwork. 14. Storm water treatment is required when 5,000 square feet or more of hydraulically- connected pavement is created and/or redeveloped by a project. Treatment of storm water runoff from hydraulically-connected pavement must occur, per City standards, prior to discharge of the storm water from the site, or to a stream, wetland, or underground infiltration system. 15. If sui!able soils deist on the site, surface stormwater infiltration systems (e.g., pervious pavers or surface ponding areas and/or swales) may be used to hydraulically disconnect pavement. From a stormwater treatment standpoint, for a pavement area to be considered hydraulically-disconnected, stormwater runoff from at least the 6-month, 24-hour storm must be fully retained and/or infiltrated. 161he options for treatment of runoff from hydraulically-connected pavement are: a) an infiltration basin, if suitable soils exist on the site b) a wetpond c) a constructed wetland d) a Stormwater360 StormFilter, with pretreatment e) an alternative stormwater treatment technology deemed, by the City of Everett, to be technically equivalent to the above options 17. If suitable soils exist on the site, underground infiltration systems (e.g., infiltration trenches) or surface stormwater infiltration systems (e.g., splash blocks, pervious pavers, or surface ponding areas and/or swales) may be used to avoid creating hydraulically-connected impervious area from a stormwater detention standpoint. Section 3-2.2 of the City's Stormwaler Management Manual lists site and design criteria that must be met. 18. From a stormwater detention standpoint, for an impervious area to be considered hydraulically-disconnected, stormwater runoff from the 100-year, 24-hour storm must be fully retained and/or infiltrated—without resulting in significant potential for adverse effects from the infiltrated water (such as slope saturation or migration to crawlspaces and/or basements). However, if the on-site soils cannot support full infiltration of the 100-year, 24- hour storm, partial infiltration may still be feasible to meet allowable stormwater release requirements. 19.The stormwater runoff from a portion cf the site is detained in an existing stormwater detention facility. This detention facility will be eliminated as part of this project. For the purpose of determining stormwater detention requirements for the proposed project, the allowable release rates for the portion of the project served by the existing detention facility shall be less than or equal to the existing release rates from the existing detention facility. Iz�b