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As described in Section 4, water quality treatment will be provided for the disturbed area prior to flow control <br /> treatment through an R-Tank full-infiltration system. See Appendix B for disturbed area water quality treatment <br /> design rates and Appendix J for water quality treatment details. <br /> MINIMUM REQUIREMENT 7: FLOW CONTROL <br /> This project proposes disturbance of 10,000 square feet or more of effective impervious surfaces in a single <br /> threshold discharge area and is subject to the flow control performance standard per preapplication meeting <br /> with the City of Everett,August 17th, 2022. <br /> To meet the flow control performance standard, stormwater discharge shall match developed discharge <br /> durations to existing site durations for the range of existing discharge rates from the 50% of the 2-year peak <br /> flow up to the full 50-year peak flow. The pre-developed condition will be a forested land cover. <br /> Flow control will be provided for the new roof area by a StormChamber detention system and for the disturbed <br /> area (through an in-kind area swap) by an R-Tank full-infiltration system. Refer to Section 4 below for <br /> additional information. <br /> MINIMUM REQUIREMENT 8: WETLANDS PROTECTION <br /> There are no wetlands in the vicinity of the project. No wetlands protection is proposed. <br /> MINIMUM REQUIREMENT 9: OPERATION AND MAINTENANCE <br /> Private storm drainage improvements will be operated and maintained by the property owner unless stated <br /> otherwise.An Operation and Maintenance manual summarizing best practices is provided in Appendix G. The <br /> City of Everett will operate and maintain storm drainage improvements constructed in the right-of-way. <br /> A Declaration of Covenant and Grant of Easement to City of Everett will be provided in a future submittal. <br /> 4. Flow Control <br /> THRESHOLD <br /> Per DOE Manual Section 1-3.4.7 MR7: Flow Control, each TDA within a project that has a total of 10,000 <br /> square feet or more of effective impervious surfaces shall meet the flow control performance standard below. <br /> FLOW CONTROL PERFORMANCE STANDARD <br /> To meet the flow control performance standard, stormwater discharge shall match developed discharge <br /> durations to existing site durations for the range of existing discharge rates from the 50% of the 2-year peak <br /> flow up to the full 50-year peak flow. The pre-developed condition will be a forested land cover. <br /> The disturbed area on-site is not able to be fully captured for flow control due to the shallow municipal storm <br /> main in Evergreen Way. To meet flow control standards for the disturbed area on-site, two flow control systems <br /> are proposed. <br /> KPFF Consulting Engineers <br /> 6 <br />