Agenda - Public Works Committee - 09/17/2024

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5. 3. Public Works Committee Meeting Date: 09/17/2024 Primary Strategic Plan Initiative: Address infrastructure needs. Title: Consider Recommendation to City Council to Accept Bids and Award Contract for Improvement Project #25- 01, Rivers Bend Regional Stormwater Improvements Purpose/Background: Purpose: The purpose of this case is to consider a recommendation to the City Council to accept bids and award a contract for construction of Improvement Project #25-01, Rivers Bend Regional Stormwater Improvements. Background: In June of 2016, the Anoka Conservation District completed a Stormwater Retrofit Analysis for the City of Ramsey and the Lower Rum River Watershed Management Organization (LRRWMO) to identify and rank potential improvement projects that drain to the Mississippi and Rum Rivers. The Stormwater Retrofit Analysis recommended modifying a wetland within Rivers Bend Park to increase the volume of stormwater runoff storage provided by this wetland that currently treats runoff from a 38-acre catchment area for the purpose of reducing sediment and phosphorus loads that can end up in the receiving water, which is an oxbow of the Rum River. See Project ID: RR8-A on page 89 of the attached modified version of the Stormwater Retrofit Analysis for reference. In the Fall of 2023, the Lightbridge Academy submitted a commercial development application so staff began working with the developer to address their stormwater management requirements. This development is located within the City of Ramsey's East Drinking Water Supply Management Area (DWSMA) where infiltration of stormwater is prohibited so staff reached out to the Lower Rum River Watershed Management Organization (LRRWMO) to confirm that the developer could purchase credits to utilize a portion of The COR regional infiltration basin to comply with the LRRWMO's volume retention requirements. When The COR regional infiltration basin was constructed, it was believed that the basin could be used to accommodate development within the East and West DWSMA's. However, the LRRWMO's engineer, BARR Engineering, recently informed staff that since the two DWSMA's drain to different water bodies (the East DWSMA drains to the Rum River and the West (The COR) DWSMA drains to the Mississippi River) Lightbridge Academy cannot simply pay a fee to use The COR infiltration basin. Discussions then turned to how Lightbridge can comply with LRRWMO requirements for stormwater runoff rate control and water quality improvements. The developer's engineer stated they cannot provide these improvements on their site so they asked if the City could accommodate these requirements. After discussions with the LRRWMO's engineer it was determined that the City needed to construct stormwater management facility improvements on the west edge of Rivers Bend Park, West of the existing wetland that currently treats all stormwater runoff from the 3 8-acre catchment as addressed in the ACD's Stormwater Retrofit Analysis, and that the existing wetland should not be impacted. This existing wetland is undersized and does not meet the rate control and water quality treatment requirements per current LRRWMO stormwater standards for the 38- acre catchment that includes several undeveloped parcels including the Lightbridge Academy parcel. Since this 3 8-acre catchment is located within the City of Ramsey's East Drinking Water Supply Management Area (DWSMA), where infiltration of stormwater is prohibited, the pond must be lined. The LRRWMO Management Plan describes/defines sites, such as those located within a DWSMA, as infeasible or inappropriate for infiltration and identifies other scenarios for the permittee to investigate. Volume retention requirements can either be provided on -site as part of the Rivers Bend Regional Stormwater Improvements by