3900 BROADWAY BASE FILE 2016-01-01 MF Import

CITV OF EVERETT STORMWATER MANAGEMENT MANUAL � Chapter 3 - Standards and Specifications for Best Management Practices 3.1 Introauction BMPs arc defined as schedulcs of acrivities,prohibitions ofpractices,maintenance procedutes,and swctural aodlor managerial pcacHces,that when used singly or in combinalion,prevent or reducc tha release of pollutents to waters of Washington. This chaptet contaias standards and specificatioos for tempocary$MPs ro be used as eppficable during the construction phase of a pmject. Chupter 3.1 contains the standards and specifications for source control BMPs. Chapter 3.3 conteins the stendards and specifications for runoff conveyance and treatrnent BMPs. The standazds for each individual BMP are dividecl into four sections: 1. Putpose 2. CondiHons otUse • 3. Design end Installatinn Specifications 4. Maintenance Standazds. Note that the"conditions of use"always rofers to site conditions. As sile conditions change,BMPs must be changed to remain in compliance. Information on sheam bank stabilization is available in the bitegra�ed Stream6ank Proteceon Guidelines, ) �Vashington 5tate Department of Fish and Wildlife(WDFN�,2003. � �'he standards end specificatioas in this chapter are not intended to limit any innovative or creative effort co effectively conhol erosion and sedimentation. In those instanees where appropriate HMPs are not in Ihis chapter,experimental management practias can be coasidered. Minor modifications ta standard practices mey also be employed. However,such practices must be approved by the City before they may be used. All experimental management practices and modified standard praceces are rcquircd m achieve the same or better performance than the BMPs listed in this chapter. 3.2 Source Control Best Management Practices 3.2.1 BMP C701: Preserving Natural Vegetation Purpose The p�:'pose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site dishuban:e is the single most effective method for reducing crosion. For example,coniCers can hold up to about 50 percent of all rain that falls during a storm. Up to 20 to 30 perccnt of this rain tnay never reach the ground but is taken up by thc tree or cvaporates. Another bcnefit is thet the rain hcld in the tree can be released slowly to the ground after the stortn. Conditions of Use 1. Natui�l vegetation should be preserved on steep slopes,ncar perennial and intertnittcnt watercourses or swales,and on building sites in wooded aroas. 2. As requircd by thc City. Volume II—Construction Stormwater Pollutiun Prevention 3-1