12-01-2021 Council Packet - Laserfiche WebLink

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Prepared by: Bolton & Menk, Inc. WOODLYNN AVENUE 2022 Street & Utility Improvements (Woodlynn Ave, Ryan Dr) ǀ 0N1.125241 Page 11 maximum of 2.5” of runoff over their tributary impervious surfaces. · Water Quality Developments must incorporate BMP’s that achieve 90% total suspended solids (TSS) removal from the disturbed area of the project on an annual basis. If applicants have sufficiently addressed the above Volume Reduction requirement, then TSS removal requirements are generally considered met without additional documentation – however, additional water quality calculations and/or water quality modeling may be requested. Presently, the infrastructure that supports the Woodlynn industrial park includes zero accommodations for Rate Control, Volume Reduction, and Water Quality. This, coupled with the very limited right-of-way, makes it very challenging to meet watershed requirements within the sub-watershed. However, the City currently has a credit balance with the watershed for providing excess volume control on previous City projects. A portion of this credit balance will likely be used to satisfy the volume control requirements on this project. · RWMWD requires project staff to first attempt to install improvements within the sub-watershed being permitted. Due to the space limitations discussed previously, RWMWD allows off-site treatment secondary option. When offsite treatment cannot be achieved, RWMWD allows the applicant to use its credit balance OR to pay into a stormwater bank at a rate of approximately $100,000 per acre treated. Project staff will attempt to install rain gardens or other BMP’s along other streets within the 2022 Street Improvement Project (Ryan Drive, Yorkton Ridge, Maple Lane, and Jackson Street) to meet the permit requirements for Woodlynn Avenue. In the event the permit requirements cannot be met off-site, the City will need to use existing credits to satisfy watershed requirements.