Opportunity

Built around 1900, the oldest sewers in greater Cleveland carry sewage, stormwater, and industrial waste in a single pipe. More than 60 times a year, after heavy rainfall, sewers in the Euclid Creek area overflow, threatening the quality of waterways.

In 2010, the sewer district reached agreement with the US and Ohio EPA and the US Department of Justice on a new plan to meet the requirements of the Clean Water Act over a period of 25 years.

Solution

The Euclid Creek Tunnel was the first of seven planned storage tunnels that will relieve overflows in the Cleveland sewer system. (See video.) The tunnel was designed to hold about 70 million gallons (265,000 cubic meters) of combined stormwater and wastewater. After each heavy rain, the combined sewage is pumped to the Easterly Wastewater Treatment Plant.

Located 190 to 220 feet (58 to 67 meters) below ground, the tunnel is 18,000 feet (5.5 kilometers) long and 24 feet (7.3 meters) in diameter. About 3,000 feet (914 meters) of the tunnel passes underneath Lake Erie.

A tunnel boring machine (TBM) known as Mackenzie bored through shale to create the tunnel. Mott MacDonald was the lead consultant responsible for overall project management, overall project administration, TBM specifications, and design of the tunnel lining, ventilation, and other aspects of the project.

Mott MacDonald introduced several key innovations:

• Bolted, gasketed, precast concrete segments were used to build the tunnel. The use of concrete segments in rock is rare, and few if any projects had used them in shale.
• The concrete segments were reinforced with steel fiber instead of rebar, another feature that is rare in the US.
• A two-part grout system was used, apparently the only one of its kind in the world. To fill the space between the concrete segments and the rock wall, grout was injected through the tail of the TBM.

Our work on the tunnel required a successful collaboration between contractor, machine supplier, grouting specialists, and others.

Outcome

The use of steel-fiber-reinforced concrete segments cut four months from the construction schedule and saved the sewer district considerable costs.

Our design enabled one-pass construction of the tunnel, reducing risks due to overbreaks and mine stoppages, decreased infiltration, and an increase in quality and safety. The contractor was able to bore the tunnel at rates of up to 110 to 130 feet (33 to 40 meters) per day.

Completed in 2013, the Euclid Creek Tunnel now prevents millions of gallons of overflow sewage from reaching Euclid Creek and Lake Erie, helping safeguard public health and the environment in the greater Cleveland area.

In 2021, the Easterly CSO Tunnel System (including the Euclid Creek Tunnel, Dugway Storage Tunnel, and Easterly Tunnel Dewatering Pump Station) received the Grand Award from the Ohio chapter of the American Council of Engineering Companies (ACEC).