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RESOLUTION AUTHORIZING AN AGREEMENT WITH THE COUNTY OF ST. LOUIS FOR A NEW STORMWATER CONVEYANCE AND GREEN INFRASTRUCTURE SYSTEM ON AND UNDER WOODLAND AVENUE AND WITHIN HARTLEY PARK, AT NO COST TO THE CITY.
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CITY PROPOSAL:
RESOLVED, that the proper city officials are hereby authorized to enter into an agreement, substantially in the form attached as Exhibit 1, with the County of St. for a new stormwater conveyance and green infrastructure system on and under Woodland Avenue and within Hartley Park, at no cost to the City.
Statement of Purpose
STATEMENT OF PURPOSE: This resolution authorizes an agreement with the County of St. Louis (the “County”) for a new stormwater conveyance and green infrastructure system on and under Woodland Avenue and within Hartley Park, at no cost to the City.
The County has a construction project scheduled in 2023 that involves re-paving and other upgrades to Woodland Avenue (CSAH 9) between Anoka Avenue and Snively Road in the City of Duluth (the “County Project”). During the preliminary design stage of the County Project, the County and City identified the potential to use an area along the eastern edge of Hartley Park to treat a portion of the stormwater conveyed by the Woodland Avenue storm sewer. The storm sewer collects runoff from various City streets in addition to Woodland Avenue. The portion of the Project within Hartley Park will create wetlands for stormwater infiltration and restore cold water flow to a trout stream. A conceptual design of the Project and the wetland areas to be created are shown on Exhibit A attached to Exhibit 1.
In 2021, the County contracted with SEH, Inc. to provide preliminary green infrastructure design. At that time, it was anticipated that the City would provide the County an easement to construct and maintain a new treatment system on land alongside Woodland Avenue. During review of the preliminary design by an external stakeholder group, it was suggested-and eventually decided-that a better approach to restore natural hydrology and treat a larger volume of runoff in a manner that is aligned with and protective of park aesthetics would be to construct a treatment system that begins on Woodland Avenue and then flows to treatment systems located farther from Woodland Avenue into Hartley Park. It is anticipated that, following pre-treatment, the primary runoff treatment approach will consist of constructed wetlands and/or biofiltration basins. The stormwater and green infrastructure to be constructed is intended to have minimal maintenance, with the majority of the frequent/annual maintenance for heavy sediment and trash/debris picked up in the County in its pretreatment structure on Woodland Avenue.
The County received a grant from the U.S. Army Corps of Engineers (the “Corps”) under which the Corps will reimburse the County for 75% of Project costs, up to $600,000, to design and construct a green infrastructure runoff treatment system. The County will cover 25% of Project costs, up to $200,000, for a total project budget of $800,000. The Project will be completed at no cost to the City other than staff time for consultant and coordination. The County will be responsible to administer and comply with the grant agreement with the Corps.
The objectives of the Project are to:
1. Reduce impacts to Tischer Creek associated with existing stormwater discharge, including the stream’s failure to meet water quality standards for e-coli.
2. Sustain cool water base flow to Tischer Creek.
3. Improve resilience (i.e., protect downstream infrastructure) by reducing flood risks associated with large runoff events.
4. Avoid increased risk of flooding at Hartley Park Nature Center buildings.
5. Minimize time and cost for post-construction operation and maintenance.
6. Protect existing wetlands and compliment or improve park aesthetics by emulating natural conditions in accordance with Duluth Natural Area Plan for Hartley Park.
7. Provide water quality educational opportunities.