Trenchless Technology

OCT 2018

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W W W.T R E N C H L E S S T EC H N O LO GY.C O M 47 ter 's proactive asset management pro - gram, numerous sewers are planned to be rehabilitated using trenchless technologies. In April 2016, the City 's Engineer- ing and Construction Division award- ed rehabilitation of the Humber sani- tary trunk sewer to Southland Renda of Canada JV for an amount of $20.3 million (CAD). The project consultant is Jacobs (formerly CH2M Hill Can- ada) providing design, construction administration and site inspections services as part of a multi-year trunk sewer rehabilitation program started in 2013. The goals of the rehabilitation proj- ect are to establish a corrosion protec- tion barrier, and extend the sewer ser- vice life for 100 years. Given the high degree of project complexity combined with the high impact on the environ- ment and surrounding community, the project team adopted sliplining in live Œlow conditions, a less intrusive and cost-effective rehabilitation method. Construction began in June 2016 and is anticipated to be completed by December 2018. "This project is Toronto Water 's lon- gest-ever sliplining project for a large diameter sanitary trunk sewer," says Adam Zietara, manager Toronto Wa- ter, District Operational Services. " We commend Southland Renda of Canada, Jacobs and the City 's Engineering and Construction project team for their in- novative and calculated risk- taking ap- proach to deliver the sliplining portion of the work on time and on budget." Built in 1959, Œive years after Hur- ricane Hazel hit southern Ontario, the Humber sanitary trunk sewer conveys wastewater collected from Etobicoke, on the northwest side of Toronto, to the Humber treatment plant . The wastewater is treated at the plant be- fore being discharged into Lake Ontar- io. The rehabilitated section is located nearby residential areas within the Humber River Valley Parklands, along the Humber River and undercrosses the Humber River at several locations. The rehabilitation scope comprised the 1.5-mile section of 59-in . to 65- in. diameter Humber sanitary trunk sewer and a 220-ft section of 28-in. di- ameter Chapman sanitary trunk sewer using a Hobas glass Œiber reinforced pipe (GRP) pipe and the rehabilitation of associated maintenance holes us- ing chemical grout to seal active inŒil - tration, and the application of sprayed interior corrosion resistant coating . The Humber sanitary trunk sewer passes through a sensitive ravine environment that is classiŒied as an Environmentally SigniŒicant Area by City Parks and the Conservation Au- thority. This sensitive location posed numerous constraints and challenges during design and construction in- cluding limited access to the site and requirements for temporary and per- manent access agreements through parklands and trails, temporary ac- cess roadways and extensive tree re - movals. The design permitted for partial sanitary bypass for sliplining installa- tion in live Œlow conditions based on Œlow upstream of the project limits. The contractor chose to work in full Œlow condition without a bypass. The Œlood plain conditions and multiple changes in the alignment underneath the Humber River at depths between 16 and 43 ft posed signiŒicant accessi- bility and constructability challenges. The contractor used eight tempo- rary shafts for sliplining installation lengths of 656 to 1,640 ft. Reinstate- ment of local PVC and concrete sewer connections along the rehabilitated section was successfully completed using special Hobas couplings and Œitting. The sliplining operations in- volved extensive manual labor, excep- tional health and safety measures at temporary access shafts, reliable on- line Œlow monitoring data and coordi- nation with operations staff. To date, the contractor has complet- ed the full scope of sliplining and is now working on site restoration. Res- toration includes trails, topsoil and sod, tree planting and seeding , and reinstatement of park utilities. " Despite of all the challenges, the contractor completed sliplining with hard work and with support from their head ofŒice," says Prapan Dave, manager of design and construction trunk sewers and transmission mains, Toronto Engineering and Construc- tion Services. " It is evident that the contractor 's perseverance, innovation, adaptability to difŒicult new site con- ditions and continuous improvement on the job made this sliplining com- ponent a success." Mariana Balaban, P.Eng., PhD, is senior project manager linear underground infrastructure, Toronto Engineering & Construction Services.

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