The Northeast Ohio Regional Sewer District reported that contractor Salini Impregilo/Healy achieved TBM hole through on March 21, completing the 3-mile long Dugway Storage Tunnel. Salini Impregilo/Healy was the low bidder in September 2014 with a bid of $153.3 million.
The Dugway Storage Tunnel project involves the installation of a 24-ft diameter storage tunnel extending approximately 15,000 ft in length from its connection to the Euclid Creek Tunnel (ECT) at the Nine Mile Site to its terminus near Superior Avenue/ Lakeview Road.
The tunnel was constructed with a Herrenknecht TBM that was previously used on the Euclid Creek Tunnel. After finishing mining the Euclid Creek Tunnel in 2013, the TBM was re-launched beginning in March 2016.
The alignment passed predominantly through Chagrin Shale at depths approaching 200 ft below ground level. The project also includes several consolidation sewers, diversion structures, and drop shafts to capture and store CSO from the Dugway service area. The diversion systems feeding the drop structures will be equipped with the inflow control gates to manage the dynamic flow within the ECT/DST tunnel system.
The Dugway Storage Tunnel is the second in a series of huge Project Clean lake tunnels designed to reduce the volume of combined sewage that reaches Lake Erie during heavy storms. The tunnels, in addition to smart green-infrastructure investments and treatment-plant improvements, will reduce overflow volumes by more than 4 billion gallons per year when complete in 2036.