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 10 3. Sanitary Sewer Improvements The sanitary sewer system is in good condition and is proposed to be left in place. Existing sanitary structures located in the reconstructed pavement will receive new castings and be adjusted to the new pavement elevations. This typically involves removal of the existing casting and final adjustment and installation of the new casting following the base course of pavement. New castings will also be fitted with external I/I barriers. Additionally, any benches and inverts that have deteriorated within existing structures will receive mud work. 4. Storm Sewer Improvements The existing storm sewer system on the west portion of Woodlynn Avenue is in good condition and is proposed to be left in place. Existing structures in the reclamation area with castings or adjustment rings in poor condition will be furnished and replaced. Additionally, minor mud work repairs to deteriorating inverts and doghouses will be completed as needed. The addition of curb & gutter to the east portion of Woodlynn Avenue will result in an increase in stormwater directed toward the eastern outfall. Capacity improvements are proposed to the downstream section of the storm sewer system to relieve ponding and system pressurization. This will include: · Installation of new catch basins · Larger storm sewer pipe · Replacement of existing storm manholes · Installation of a new and larger outlet to the Waterworks Trail easement The proposed improvements would directly address historical drainage issues and increase system capacity. 5. Water Quality Improvements The proposed reconstruction of Woodlynn Avenue east of the railroad tracks will result in land disturbance more than 1 acre, the threshold that triggers a permit from the Ramsey-Washington Metro Watershed District (RWMWD). The permit requires that the roadway be designed to achieve minimum standards for: · Rate Control Proposed runoff rates shall not exceed existing runoff rates for the 2, 10, and 100-year critical storm events using Atlas 14 rainfall depths and MSE3 rainfall distributions. · Volume Reduction Stormwater runoff volume reduction shall be achieved onsite in the amount of 1.1 inches of rainfall off new and reconstructed impervious surfaces. To achieve the most effective treatment, stormwater Best Management Practices (BMP’s) may retain a Exhibit 5 – Storm Sewer Structure Installation