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DESIGN AND CONSTRUCTION STANDARDS AND SPECIFICATIONS <br /> Department of Ecology for stormwater facility design in Western Washington.Modeling shall be performed <br /> using a 5-minute timestep. <br /> Additional Requirement <br /> Flow Control BMPs shall be selected, designed, and maintained in accordance with the City's adopted <br /> Stormwater Management Manual and Section 4 of the DCSS, except as noted in this Section. The Flow <br /> Control Performance Standard may be achieved through any combination of onsite stormwater management <br /> techniques,flow control BMPs and selective site design which can be demonstrated to achieve the standard. <br /> 6-10.1 (2) DESIGN DOCUMENTATION <br /> Development applicants shall provide documentation of compliance with the Combined Sewer Area <br /> stormwater standards.Development applications shall include the following: <br /> a. Stormwater Report which includes the following elements: <br /> • Narrative description of the proposed project, existing & proposed conditions, and proposed <br /> stormwater facilities to be implemented. <br /> • Existing and proposed site maps identifying land cover types used in the stormwater analysis <br /> • Numeric summary of existing and proposed surface areas within the site and contributing <br /> offsite areas <br /> • Determination of erosion control risks and proposed measures to control erosion and <br /> sedimentation. <br /> • Offsite analysis narrative description and figure describing upstream areas which contribute <br /> runoff to the site and the downstream system which will receive runoff from the site.Describe <br /> any identified issues which may affect or could be exacerbated by the project. <br /> • Flow control design and sizing calculations <br /> • Conveyance pipe sizing calculations <br /> • Other reports and data required to prepare the stormwater facility design <br /> b. Construction plans for proposed stormwater facilities <br /> c. Operations and maintenance manual for all proposed stormwater facilities. <br /> d. Maintenance covenant for owner conducted maintenance of all stormwater facilities. <br /> 6-10.2 COMBINED SEWER CONVEYANCE SYSTEM <br /> 6-10.2(1) MATERIALS AND CONSTRUCTION <br /> Elements of the combined sewer system which convey only stormwater, such as catch basins and <br /> stormwater piping shall be constructed in accordance with the stormwater conveyance system requirements <br /> in Section 4-2. <br /> Elements of the combined sewer system which convey only sanitary sewage, or a combination of <br /> stormwater runoff and sanitary sewage,shall be designed in accordance with Section 6-7 and 6-8. <br /> SANITARY SEWERS 6-16 <br />