Video: Boring Machine Reaches West Hartford In MDC Tunnel Project

WEST HARTFORD, CT — Metropolitan District officials said a major goal was reached this week in the South Hartford Conveyance and Storage Tunnel project when the boring machine "Iris" reached its destination at the MDC's retrieval facility on Talcott Road in West Hartford.

The tunnel boring machine began its journey in the Spring of 2019 across the street from the MDC's Hartford Water Pollution Control Facility on Brainard Road in Hartford. It has now traveled 4 miles, 200 feet below the surface before busting through the retrieval shaft on Talcott Road Tuesday.

The SHCST is a deep rock tunnel designed to temporarily store excess combined wastewater and storm water during rain events, and then convey the flows to the treatment plant. The tunnel’s capacity of 41.5 million gallons will help prevent the HWPCF from being "overwhelmed" during storms, MDC officials said.

The 18-foot diameter tunnel is built in bedrock approximately 200 feet below ground. The tunnel is a major component of the MDC's Clean Water Project, a $2 billion-plus wastewater system improvement program required by the federal Environmental Protection Agency and the state of Department of Energy and Environmental Protection.

The project is the first of its kind in Connecticut and the tunnel construction portion of the project, which cost approximately $279 million, is the largest contract ever awarded by the MDC, and the largest project ever funded by the State Clean Water Fund.

The Kenny Obayashi joint venture was awarded the contract to build the tunnel and in addition, the MDC also partnered with AECOM on the engineering design and Jacobs on the construction management of the project.

The tunnel, according to MDC Chief Executive Officer Scott Jellison, is a key element of the Clean Water Project because it can limit combined sewer overflows to a one-year storm level. It will eliminate overflows to the Wethersfield Cove, and ultimately benefit the entire region including the Connecticut River and Long Island Sound, he added.

"We are thrilled to have reached this milestone and are grateful to our board of commissioners as well as the federal, state and municipal officials from the MDC's towns for their part in securing critical grant and loan funding to minimize the cost of the project and impact on ratepayers. We are also thankful to our partners at DEEP for their help executing this project and making funding available,” Jellison said.

Here's a look at Iris in action: