Alternate: A Collaborative Vision: Regional Stormwater Management at 325 Blake Road

Just over 10 years ago, the Minnehaha Creek Watershed District (MCWD) recognized an opportunity with a 17-acre aging industrial site bordering their Creek. The property was a missing link in the Minnehaha Creek Greenway, borders a popular regional trail system, is located next to a planned METRO Green Line station, and has two urban stormwater discharge points that drain 270 acres directly into Minnehaha Creek. Inquiries were made with the property owner, and MCWD purchased the 325 Blake Road site in 2011. Following several years of site preparation and community outreach, MCWD and the City of Hopkins developed an innovative vision for the site centered around MCWD's ethos of 'balanced urban ecology.' The Minnehaha Creek Watershed District spans 178 square miles, including prominent waterbodies such as Lake Minnetonka, the Minneapolis Chain of Lakes, Minnehaha Creek, and Minnehaha Falls. The watershed includes eight major creeks, 129 lakes, and thousands of wetlands. The MCWD includes all or part of 27 cities and two townships in Hennepin and Carver counties. The concept for 325 Blake Road involved having MCWD retain a 4-acre portion of the site for regional stormwater treatment, riparian preservation, and public amenities; while fostering development of the remaining 13 acres of the parcel with transit-oriented, water-centric residential, commercial, and public spaces that would complement and enhance the MCWD site. In 2020, MCWD selected an HDR team as the designer for their project. In 2021, Alatus Development was selected as the developer for the remaining parcel and began advancing towards construction with an extensive range of stakeholders, including: -City of Hopkins (Public roads/utilities/parks and Tax Increment Financing) -MetroTransit (Nearby light rail corridor/station and station access Three Rivers Park District (Shared trails and access) -Hennepin County (grant funding and parcel development) -Neighborhood residents and business owners (amenities and impacts); and -MN Public Facilities Authority ($4.5M grant for stormwater treatment) MCWD and the design team understood the importance of transforming MCWD's original vision into a shared vision amongst the stakeholders to successfully advance the project. Several public listening sessions were held to establish public priorities. These priorities were carried into a design charrette with public and private partners including elected officials, planners, designers, developers, architects, and engineers. Over two days, approximately 30 participants engaged in a creative and collaborative process to refine and establish concurrence on the site layout and objectives. With the community, developer, designers, and agencies on board, the project design is approaching 100% with a portion of construction already underway. The design continues to follow the charrette concept very closely. To compensate for design constraints, an innovative treatment train was established that includes a pumped and filtered stormwater cascade. This process is embraced by MCWD and the developer, anticipated to remove nearly 100% of TSS and 74% of TP on an average annual basis. Stormwater treatment also serves as a feature for the thriving development and public realm amenities. The extensive stormwater treatment train concept includes underground pre-treatment vaults that are in line with the regional storm sewer, extended detention basins separated by a weir wall for aesthetics and long-term maintenance, a pump that conveys detained stormwater through manufactured treatment devices, and a stormwater cascade that manages hydraulics and provides filtration throughout the vegetated channel. Ultimately, regional stormwater is discharged back into an extended detention basin for a constant cycle of stormwater treatment through the system. Elsewhere on the site, green infrastructure practices including permeable pavement, rain gardens, tree trenches, and stormwater cisterns are planned for site stormwater management. This presentation focuses on reviewing key elements of project planning, stakeholder coordination, and the design charrette collaboration that helped establish consensus with key project partners and enhance the project design. The anticipated benefits of the project will be reviewed, including water quality and conservation, which was the genesis for MCWD's initial curiosity about the site, carried through to a collaborative vision of a balanced urban ecology at 325 Blake Road.