Manchester, N.H. awards contract for tunnel project to address sewer overflows

Methuen Obayashi Joint Venture has been awarded a contract for the city of Manchester, New Hampshire’s Cemetery Brook Drain Tunnel Project, the Union Leader reported.

According to city officials, this may be the largest public works project undertaken in Manchester since the construction of canals two centuries ago.

The Cemetery Brook Drain Tunnel is a 2.25-mile tunnel that once built, will measure 12.5 feet in diameter and run 30- to 80-feet underground, according to the Union Leader. The project is part of Manchester’s ongoing 20-year, $500 million combined sewer overflow program to improve water quality in the Merrimack River.

Aside from the main component of tunnel construction, the project will involve digging up streets and replacing single-pipe structures with two separated systems for sewage and stormwater.

Methuen Obayashi stated in a news release it will use a tunnel boring machine to minimize disruptions above ground. Construction will include seven drop shafts placed along the tunnel alignment. The shafts will serve as entry points for stormwater and provide access for the construction team.

Construction is expected to reach completion in 2028.

Manchester has experienced overflow problems, with stormwater overwhelming the capacity of antiquated sewer systems during periods of heavy rainfall. 

In 1999, the U.S. Environmental Protection Agency (EPA) ordered Manchester to address the problem of sewage overflowing into the river. In 2009, Manchester completed a $58 million Phase I project that covered the West Side.

 

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