The City of Toronto - Sewer Rehabilitation

Carlaw Avenue Box Culvert Rehabilitation utilizing Channeline Sewer Renovation System.

In 2005, the City of Toronto, Water and Wastewater division decided to perform necessary rehabilitation of the circa 1930’s built cast in place concrete box culvert. Man-entry inspections carried out in 2003, had confirmed structural deterioration in the pipe walls and ceiling. As with the initial rehabilitation phase of the upstream sections of culvert, it was decided to use a Grouted in Place, Glass Reinforced Plastic Panel Liner.

Due to relavitely shallow depth of around 2m and heavy traffic including TTC train traffic and tractor/trailers the 1350mm width x 1625mm height sewer liner was to conform the the WRC SRM 4th Edition, Type 1 Lining. The Cities specification called for physical properties of 1,400,000 psi Flexural Modulus and 16,000 psi Flexural Strength and a minimum 28 day compressive strength of 1,740 psi for the backfill grout.

Capital Sewer Services Inc. was awarded the project, and proposed the use of the tried and tested Channeline Renovation system. The project was scheduled to start in late October of 2005.

An initial man-entry survey of the pipe was carried out to determine the exact dimensions of the structure, a panel template was constructed to mirror the dimensions of the proposed GRP panel. This was then articulated through the entire length of the existing sewer to ensure that the panels would fit.

After obtaining the relevant permits for road closure, street occupation permits etc, Capitals crew mobilized to site to close the two center lanes of this very busy downtown street, for staging of the panels and to excavate a 4.5m x 2.4m access pit. This pit would form the entrance for construction works and the location of a new manhole.

118 Channeline panels were inserted into the sewer through the access pit, these were then transported to the working face utilizing a purpose built carrier. Once homed, the bell and spigot joints were filled with polyurethane construction sealant to ensure that the liner was leak proof during backfilling operations.

Brick bulkheads were then constructed to seal the ends of the liner and service connections were reinstated and re-built with structural mesh and hydraulic cement.

Approximately 190 cubic meters of ready mixed, cement/flyash based grout was pumped into the annular space between the panel and host pipe. This took approximately 2 weeks and was done in 4 consecutive lifts.

The entire project was completed in just over 7 weeks in temperatures as low as minus 15 degrees celcius. However, in comparision to the disruption that traditional open cut methods would have caused, the City made a wise choice in chosing this particular Trenchless method.