Trenchless Technology

OCT 2018

Trenchless Technology is the premier communications vehicle for the trenchless industry. Through our multiple platforms, readers receive insights into the trenchless industry, as well as keep connected to the latest news, products and projects.

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Page 34 of 91

ties, it was critical to stay in contact with property owners throughout the project . The project team began engaging with these and other stake- holders early on — during the design process — through a multi-channel communications plan that included formal open houses. The project team invited the whole community, issuing personalized invitations to waterfront property owners, and had all collabo - rators (HW, Robinson Consultants, CBCL and Liquiforce) present . The ambitious goals of this project presented several signi€icant chal - lenges, including: extremely limited access and steep topography, an ac- celerated completion schedule, com- plex engineering design for CIPP in an arch- shaped pipe. The location and to - pography surrounding the sewer pre- sented signi€icant accessibility chal - lenges that resulted in approximately 3,000 m of the 4,000 m being installed from four access locations. This re- sulted in numerous CIPP installation lengths being completed in excess of 400 m. The CIPP installation lengths averaged more than 400 m, with the longest installation completed at 680 m setting a new Canadian record. A unique complication required the 680 m long inversion to include a transi- tion from 1,200 mm to 1,425 mm. The transition section was built into the felt liner designed speci€ically for the pipe section, with the transition oc- curring 50 m from the tail manhole. Complicating these installations was the need to fabricate the CIPP liners on site due to the load restrictions of Canadian National Railway bridges. CIPP is typically impregnated with resin and shipped to a project site via refrigerated truck. For the NATS proj- ect , due to the load-restricted bridges and the size of the CIPP to be installed, the resin impregnated liners for each installation could not be transport- ed across the bridges complete on a single truck. The resin volumes were typically 90,719 kg , with the largest single installation requiring approxi- mately 136,078 kg . This meant it was necessary to impregnate the felt tube with resin on site directly over the installation manhole, allowing small resin tankers (shuttles) to cross the bridge in multiple loads to comply with bridge weight restrictions. The site's topography also presented chal - lenges associated with the laydown area for the on- site wet-out and cur- ing of the liner. The most dif€icult lo - cation required the laydown area to be set up on a 15 percent grade, requir- ing a large scaffolding structure to be erected 9.14 m high at one end and at grade on the other. This approach was effective for most of the locations, however one location lacked a suf€i- cient working area for onsite wet-out facilities. To get around this unique situation , an in€ield splice joining two sections of wet CIPP was completed mid-inversion, allowing two wetout sections to be transported across the bridge separately. W W W.T R E N C H L E S S T EC H N O LO GY.C O M 35 Project Owner: Halifax Water Engineer: Robinson Consultants Inc./CBCL Limited Contractor: Liquiforce, Insituform, UniJet, Empipe and Atlas Dewatering Manufacturer/Supplier: AOC Value of Trenchless Project (US$) $17.5 million

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