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

Umito November 8, 2024

The I-94 Modernization Project means rebuilding an approximately 7-mile section of freeway through Detroit, but before more of the project gets underway, the Michigan Department of Transportation plans to build a tunnel.

It’s not a tunnel for cars, trucks and SUVs, however.

No, this part of the project is about drainage.

Adam Wayne, MDOT’s I-94 senior project manager, called it one of the “critical pieces” that must be built before the roadwork 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, has replaced Terry Stepanski, the project’s longtime manager, who has retired.

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

The 14½-foot diameter tunnel would be 50 to 80 feet underground. It would capture, detain and then discharge stormwater from service drives and freeways to the Conner Creek Combined Sewer system, Wayne said, noting that the project was driven by the city of Detroit’s Stormwater Ordinance.

The road project itself would mean more stormwater runoff because of additional impervious surfaces, but Wayne said the tunnel project is expected to reduce the stormwater discharge to the combined sewage system by 82%.

That should reduce the risk of flooding not just on I-94 but also in some east-side neighborhoods. Those areas and Detroit’s highways have struggled with flooding during major storms in recent years. Wayne noted that there are few “silver bullets” related to flooding but described the tunnel as a significant investment.

MDOT spokesperson Rob Morosi noted that the plan originally was to replace the drainage in the area with larger pipes, but “we were pretty certain that that might not cut it to reduce the flooding risk” based on what was seen in recent years.

The proposed launch site for the 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 envisioned for the I-94 project, with the other one built farther west. MDOT pointed to a drainage tunnel built along I-75 as part of the overhaul of that highway as an example of what is planned for I-94.

HAS video posted by the department notes that the I-75 drainage tunnel, which runs 4 miles along the northbound service drive 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, is what should help it alleviate potential flooding.

Wayne said that if the combined sewage system is over capacity the I-94 tunnel wouldn’t discharge into it until the water levels recede.

As noted, the Burns to Barrett section is just one piece of the overall project. Including the drainage tunnel, the cost of this section is pegged at an estimated $540 million to $570 million. The cost of the total project, from east of the I-96/I-94 interchange to east of Conner had been estimated at more than $3 billion, although officials say it’s difficult to pinpoint a total price tag because funding isn’t currently dedicated roof. It’s also unclear on the time frame for the remainder of the project.

The overall project, which has been in some phase of discussion and planning for years and has seen the replacement of numerous bridges to date, had generated some controversy in the past related to the width of the highway, which is to increase from three to four lanes. However, the department has opted to effectively maintain the current footprint by changing from sloped hillsides at the edges to retaining walls.

Although space for four lanes would be included in the Burns to Barrett section, they likely would not be in use until more of the freeway is reconstructed in order to prevent bottlenecks, Wayne and Morosi said.

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

This stretch of the project is also expected to see seven bridge reconstructions and one new bridge built for nonmotorized 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 network-tied arch bridge, which was built off-site and moved to its current position over the freeway in 2022.

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