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I-94 project will include massive drainage tunnel on Detroit’s east side

Umito November 8, 2024

The I-94 modernization project involves rebuilding a roughly 7-mile stretch of highway through Detroit, but before the project begins, the Michigan Department of Transportation plans to build a tunnel.

This is not a tunnel for cars, trucks and SUVs, however.

No, this part of the project concerns drainage.

Adam Wayne, MDOT’s I-94 senior project manager, called it “critical pieces” that must be built before road work begins in an upcoming phase from Burns (west of Gratiot) to Barrett Avenue (east of Conner). Wayne, who has been with MDOT for about eight years, replaced longtime project manager Terry Stepanski, who retired.

MDOT plans to begin construction of a drainage tunnel in 2026 before moving on to road and bridge work over a roughly 2-mile stretch starting in 2028 or 2029. MDOT, which has filed a number of lawsuits before Wayne County Circuit Court in recent weeks to obtain temporary construction easements to access neighboring properties for grading, has scheduled an in-person community meeting to present details and gather feedback. The meeting is scheduled for Thursday from 6 to 7:30 p.m. at the Wayne County Community College District East Campus, 5901 Conner Ave.

The 14½ foot diameter tunnel would be located between 50 and 80 feet underground. It would capture, hold and then discharge stormwater from service roads and highways to the Conner Creek combined sewer system, Wayne said, noting the project was driven by the city of Detroit’s stormwater ordinance .

The road project itself would result in more stormwater runoff due to additional impervious surfaces, but Wayne said the tunnel project is expected to reduce stormwater discharge to the combined sewer system by 82 percent.

This should reduce the risk of flooding not only on I-94 but also in some eastern neighborhoods. These areas and Detroit highways grapple with flooding during the major storms of recent years. Wayne stressed that there are few “silver bullets” related to flooding, but described the tunnel as a significant investment.

MDOT spokesman Rob Morosi noted that the initial plan was to replace the area’s drainage system with larger pipes, but “we were pretty sure that might not be enough to reduce the risk flood”, based on what has been observed in recent years.

The proposed launch site for mining operations to build the tunnel would be in the area of Cadillac and westbound I-94. It would be one of two drainage tunnels considered for the I-94 project, with the other being built further west. MDOT cited a drainage tunnel built along I-75 as part of that highway’s redesign as an example of what’s planned for I-94.

A video posted by department notes that the I-75 drainage tunnel, which stretches 4 miles along the northbound service road between 8 Mile and 12 Mile roads, can hold more than 25 million gallons of water. The tunnel’s ability to store a significant amount of stormwater during major rain events, allowing time for other areas to discharge into the system, should help it mitigate potential flooding.

Wayne said if the combined sewer system was over capacity, the I-94 tunnel would not discharge into it until water levels drop.

As noted, the Burns to Barrett section is only one element of the overall project. Including the drainage tunnel, the cost of this section is estimated between $540 and $570 million. The total cost of the project, from east of the I-96/I-94 interchange to east of Conner, has been estimated at more than $3 billion, although officials say it is difficult to determine the total price because funding is not currently dedicated. to this. It’s also unclear what the timeline is for the rest of the project.

The overall project, which has been in the discussion and planning phase for years and has seen the replacement of numerous bridges to date, has sparked some controversy in the past over the width of the highway, which is to increase from three at four. ways. However, the department chose to effectively maintain the current footprint by replacing the slopes of the border hills with retaining walls.

Although space for four lanes is included in the Burns to Barrett stretch, they likely won’t be used until more of the highway is rebuilt to avoid bottlenecks, said Wayne and Morosi.

The intention is to maintain two lanes of traffic in each direction during construction, with closures limited to specific cases, such as to deal with utilities.

This section of the project is also expected to see seven bridges rebuilt and a new bridge constructed for non-motorized traffic, near Conner, for the Iron Belle Trailaccording to Wayne. Previous bridge work for the I-94 project includes the Second Avenue Bridge, the state’s first grid-connected arch bridge, which was built off-site and moved to its current position on the highway in 2022.

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