The Northwest Arm is a valuable recreational, economic and quality of life asset to our community. Maintaining the water quality of the Arm is important. The trunk sewer that services the area was over 100 years old and showing its age. Repairing the four kilometres of the large diameter sewer from the Armdale Roundabout to Point Pleasant Park, through residential backyards, was a significant engineering, logistics and community relations exercise.
The project was budgeted at $23million and the timeline for completion was very tight. Work had to be complete by March 2018 in order to qualify for Clean Water and Wastewater Funding, so crews went right to work.
Liquiforce was the contractor awarded the project and by June 20th the work had gotten underway with a subcontracted workforce which included Unijet, Insituform, EmPipe, Atlas Dewatering, and a local civil contractor G&R Kelly to clean and line the existing sewer using Cure-In-Place-Pipe (CIPP) technology.
Once the sewer was cleaned and the bypass systems in place (which allowed the trunk sewer to remain operational throughout the project), the lining of the sewer began. Once a lining section began, it became a 24-hour operation. One of the liner sections took six round-the-clock days to complete. The shortest liner sections were typically completed in 2 days.
A few project stats and unique challenges:
- approximately 1,000,000 lbs. of resin was used;
- one lining section was 861m, the longest large diameter liner to be placed in Canada
- this section was further complicated by the 25+ laterals and interconnections over it’s 861m length
- as well, it transitioned from a 4ft round diameter to 4x5ft arch shape;
- one 240m lining section had to be transported in two sections and stitched together on site. This was to accommodate weight restrictions on CN’s Belmont on the Arm bridge.
- A specialized crew was flown in from out of country to complete this section as this type of stitch work is very rare, reportedly only completed once a year globally.