22 OCTOBER 2026 WorldWide Drilling Resource® Blacklick Creek Sewer Tunnelling Adapted from Information by AECOM and Michels Trenchless, Inc. When the city of Columbus, Ohio, needed to increase the capacity of its sewer line infrastructure, AECOM and Michels Trenchless, Inc. were tasked with completing the project. Using an earth pressure balance tunnel boring machine (EPB TBM), the Blacklick Creek Sanitary project included drilling a 22,620-foot linear sanitary sewer interceptor tunnel. The tunnel was installed with a 12-foot-outer-diameter reinforced tunnel. The EPB TBM was able to complete the installation in one pass. Prior to installation, the liner was corrosion protected, bolted, and gasketed then placed successfully along its nearly four-mile-long path. The EPB TBM used for the Blacklick Creek project was specially engineered to handle materials outside of its initial design. Normally suitable for soft earth, the soil on the project site was complicated with silts, sands, gravel, cobbles, rocks, and boulders; some areas even contained shale and bedrock. As part of the project, ten drop shafts with connected manholes were also constructed. Some of the shafts are 35-135 feet deep providing access to different sections of the main tunnel. Since the tunnel path also intersected gassy sections with high methane, carbon monoxide, and hydrogen sulfide, a passive odor control vault was installed. The tunnel connects residences east of Columbus, in the Reynoldsburg/New Albany area, using a collection system feeding the Southerly Wastewater Treatment Plant. The tunnel contains 12 curves, one with a 3000-foot radius, two with a 3600-foot radius, and nine with a 1300-foot radius. Tunnel junction chambers connecting new and existing infrastructure were also included. Hydrogeological, geotechnical, and geophysical studies were used to select the best method of construction for the tunnel while the EPB TBM was designed to operate in a manner which reduced impact to the surface structures, utilities, and nearby wells. The joint venture was a successful one. Earth pressure balance tunnel boring machine. Photo courtesy of Michels Trenchless. www.starironworks.com 257 Caroline Street Punxsutawney, PA 15767 800-927-0560 • 814-427-2555 Fax: 814-427-5164 Serving the Construction Industry
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