Breakthrough at Cleveland clean up operation 12 Apr 2018

Salini Impregilo and its US subsidiary The Lane Construction Corporation achieved breakthrough on March 21 2018 at the Dugway Storage Tunnel (DST), a $153-million project in Cleveland, Ohio to help reduce the flow of raw sewage into Lake Erie.

The Herrenknecht TBM broke through at the DST-8 shaft after a 4.5km journey that had started in July 2017 after delays due to difficulties sinking the starter shaft.

Breakthrough at Ohio interceptor

The 8.2m tunnel is lined with 7.3m i.d. precast tunnel segments at a depth of 60.9m to 70.1m. There are six shafts of varying diameters and depths, four gate structures, four control vaults, eight vent vaults, three drop manholes, one diversion structure and 550m of connecting tunnels and pipelines of various sizes, depths and lengths.

The launch shaft had caused problems due to difficult ground conditions which included water bearing silt and after attempting several methods of water control at the site SalinI Impregilo turned to ground freezing. Once through the water bearing silt, a concrete collar was poured around the area for stability.

Rather than replace the existing sewer system with separate sanitary and combined sewer overflow (CSO) pipelines, the Northeast Ohio Regional Sewer District, the project owner, decided to handle any additional CSO created by storm or heavy rains with a network of deep tunnels. With an annual storage capacity of more than 370 million gallons, the DST holds the water until the Easterly Wastewater Treatment Plant has the capacity to treat it.

The DST, set to go into service in 2019, is the second of seven tunnels commissioned by the Northeast Ohio Regional Sewer District under the 25-year, $3-billion Project Clean Lake to reduce CSOs. Like other cities across the United States, Cleveland must meet standards set under the Clean Water Act to reduce sewage discharges that contribute to elevated levels of bacteria, pathogens and other pollutants in streams, rivers and lakes in the surrounding area. The project will improve the quality of the water in the lakes, rivers and streams and address public health risks.

Salini Impregilo and Lane Construction are involved in similar projects elsewhere in the country. In Washington, DC, they completed the Anacostia River Tunnel and have begun work on the adjacent Northest Boundary Tunnel (NEBT), a $580-million large, deep sewer tunnel. They have also begun work on the $188-million Three Rivers Protection and Overflow Reduction Tunnel in Fort Wayne, Indiana.

The Group’s commitment to environmentally sustainable public works is also evident elsewhere in the world. In Argentina, it is working on a hydraulic tunnel as part of the government’s biggest public works project valued at $1.2 billion to clean up in the Matanza-Riachuelo Basin. In Abu Dhabi of the United Arabic Emirates, the Group completed a 25km tunnel to collect the city’s waste water.