Metropolitan Council Environmental Services (MCES), operator of the metro-area wastewater collection and treatment system, is making improvements to the existing and aging sanitary sewer system in Minneapolis. This sewer rehabilitation project is located along the north side of East Minnehaha Parkway, and the tunnel is located under Minnehaha Creek, Hiawatha Avenue and the METRO Blue Line light rail corridor. The existing tunnel is located 1½ miles northwest of Coldwater Spring, a significant cultural and historic resource.
MCES will clean the tunnel, rehabilitate the existing tunnel, and upgrade the existing regulator and electrical vaults. The work will preserve the structural integrity of the tunnel and will minimize the risk of failure.
Construction began in November of 2019 and will be completed in July 2021. A robust temporary conveyance system will be in place during construction to direct wastewater around the work site. Some impacts to park users and residents may include: lights, noise, nuisance odor release, tree removals, construction vehicle traffic and equipment parking, lane shifts and temporary Hiawatha Avenue intersection closures, parking restrictions on Hiawatha Avenue frontage road, and a bike trail closure.
Hiawatha Bicycle Trail Closure
A section of Hiawatha Bicycle Trail between the Minnehaha Creek Trail and Minnehaha Parkway will be closed throughout construction (January 2020 to July 2021) to accommodate temporary wastewater conveyance piping. Bicycle traffic will be detoured to Minnehaha Creek Trail, 34th Avenue and Minnehaha Parkway. Bike lanes with temporary striping will be created on sections of 34th Avenue crossing Minnehaha Creek and along east- and westbound Minnehaha Parkway.
MCES previously planned to replace the tunnel, and to start construction in 2017. Due to public concerns, MCES performed additional technical studies to better understand the groundwater flow connected to Coldwater Spring, and to determine if the existing tunnel could be rehabilitated rather than replaced. MCES has determined that the existing tunnel can, and should, be rehabilitated (rather than replaced) to avoid the potential for impacts to groundwater flow to Coldwater Spring.
Draft Facility Plan Amendment - Emergency Relief Structure 04/1-MN-344 Tunnel Rehabilitation - March 28, 2018 (PDF)
The Minnesota Pollution Control Agency (MPCA), as delegated by the US Environmental Protection Agency (USEPA), reviewed the facility plan amendment and determined the sewer rehabilitation poses no significant implications for preservation of historic and environmental resources, including Coldwater Spring. Therefore, the project is exempt from further Section 106 review. MCES will continue to coordinate with tribes, neighborhoods and other interested parties during construction.
The National Park Service will monitor water flows to Coldwater Spring Monday-Friday during construction even though no dewatering is expected. The National Park Service will regularly post the results of their monitoring on their website.
Anticipated Project Schedule
Contractor Bid Awarded: June 2019
Notice to Proceed: July 2019
Construction: November 2019 – July 2021