4th Street Tunnel Repair Project

MCES Project No. 807665

Text Alert Icons Project Alert

Project Update - December 18, 2019.  See Project Updates below.

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Project Description

Metropolitan Council Environmental Services (MCES), operator of the metro-area wastewater collection and treatment system, will be constructing two deep tunnel access shafts and making repairs to the existing sewer tunnel beneath 4th Street in downtown Minneapolis.

The sewer tunnel was originally constructed in 1885 and is more than 80 feet deep. A void space above the tunnel was left after it was constructed. The space has been deteriorating, allowing sandstone pieces to potentially fall and damage the sewer tunnel. To make improvements, construction crews will install two new access shafts beneath 4th Street, remove debris in the void, repair damage to the sewer tunnel, and then fill the void with grout.

Rendering graphic of soil layers present under the road on 4th Street. Just under the road is soil, followed by limestone, and sandstone on the bottom. The 8 foot steel access shaft runs from 4th Street down approximately 80 feet into the sandstone. From there, an access tunnel in the sandstone layer, leads to the existing sewer tunnel.

The access shafts will be located just east of Hennepin Avenue and Marquette Avenue, on the south side of 4th Street. Three lanes of eastbound traffic will remain open throughout the majority of the work, but they will be shifted to the north side of the road.

Project area map graphic shows the location of the sanitary sewer pipe along South 4th Street between North 1st Avenue and South Marquette Avenue noting the pipe is at a depth of approximately 85 feet. New access shafts will be installed on South 4th Street just east of Hennepin Avenue and Marquette Avenue.

The overall process will be time-consuming due to the depth of the tunnel and limitations of working in a confined space. Construction is anticipated to begin January 7, 2019 and be completed by spring 2020.

4th Street Tunnel Repair Project Overvew (PDF)

4th Street Tunnel Repair Project Area Map (PDF)

Illustration of Tunnel Access Shafts (PDF)


Project Updates


Project Update - December 18, 2019 (PDF) 351 kB

Project Update - October 7, 2019 (PDF) 574 kB

Project Update - August 7, 2019 (PDF) 399 kB

Project Update - January 30, 2019 (PDF) 218 kB

Project Contacts

For information, please contact:

Email: info@4thStreetTunnelRepair.com

Phone: 612.352.9774

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