Residents can stay current on construction schedule
Construction work will begin in August on improvements to an aging regional sanitary sewer tunnel under Minnehaha Creek near East Minnehaha Parkway. The Metropolitan Council, on June 12, approved an $18 million contract as part of the two-year, $25 million project.
Beneath the creek near Hiawatha Avenue and the METRO Blue Line is a large, aging sewer tunnel that was built in 1935. To preserve the structural integrity and reliability of the infrastructure, crews will clean the tunnel and install a liner that will create a new sewer pipe within the existing tunnel. The project also will upgrade other wastewater infrastructure in the area, including regulator and electrical vaults.
Officials with Metropolitan Council Environmental Services say despite efforts to minimize disruption, planned construction will result in inconveniences like noise, traffic, detours, and temporary above-ground wastewater conveyance pumps and pipes in the area.
Residents can keep track of the project’s status by subscribing to enewsletter or text updates and watching for online project updates. Email and phone contacts are also identified online.
Sewer rehab protects investment, safeguards public health and environment
“Typically, wastewater infrastructure is out of sight and out of mind,” said Jeannine Clancy, the Assistant General Manager of Technical Services for Environmental Services. She oversees the wastewater capital improvement program. “This project will be a visible sign of the ongoing need to rehabilitate and improve the infrastructure that protects public health and the environment.”
The region’s wastewater collection and treatment system is a vast network of pipes and plants that convey and treat about 250 million gallons of wastewater a day from 109 metro area communities and 2.6 million people. Council officials estimate the replacement value of the region’s wastewater treatment system at $7 billion.
“We have a responsibility to protect the region’s assets and investments that operate 24 hours a day, and seven days every week to help preserve water quality in the region,” said Clancy.
Limited access and project depth add to complexity
This particular segment of regional sanitary sewers collects wastewater from Edina, Richfield, and portions of south Minneapolis en route to the Metropolitan Wastewater Treatment Plant in Saint Paul.
Construction will occur on the north side of East Minnehaha Parkway to rehabilitate about 1,000 feet of sewer tunnel in and near the park. It will start just west of the creek and extend across Hiawatha Avenue to the roundabout on Minnehaha Avenue.
The tunnel crosses under the creek at about 20 feet but drops to 74 feet east of the creek. It’s the depth of the tunnel in some places and limited access to other parts of the tunnel that Council officials say make this a lengthier and more complicated project than some others.
Protecting Coldwater Spring
Council plans to line rather than replace the tunnel is to protect Coldwater Spring, about 1.5 miles south of the sewer improvement site. The less invasive method serves as a precaution to protect and avoid disrupting groundwater flow to the spring.
Coldwater Spring is a significant cultural, sacred and historic resource managed by the National Park Service. The park service agrees that the rehabilitation project will prevent the aging sewer pipe to the north from failing and won’t impede groundwater flow to the spring.
Council officials acknowledge the effects would be disastrous if the tunnel were to rupture and leak sewage into the groundwater system. Clancy says the project may result in some annoyances but is critical to preserving the amenities that residents enjoy.