Successful Sewer Bypass for 100-year-old Interceptor

The city of Saskatoon, located in the Canadian province of Saskatchewan, faced the daunting task of rehabilitating its nearly 100-year-old interceptor trunk sewer, a pipeline that transfers wastewater from all areas of the city. The city of Saskatoon selected Insituform as the prime construction contractor for the sewer rehabilitation project. Having a working relationship with Insituform, Sunbelt Rentals was awarded the sewer bypass portion of the project.

Bypass mobilization began in January 2012 to coincide with the low wastewater flows typical of the season. Our crew handled the installation and eventual operation of the temporary bypass.

The scope of work and rental equipment included:

• Bypass of 1,010 foot-long segment of 84-inch diameter sewer interceptor
• Six 18-inch Quiet Flow™ sound attenuated diesel trash pumps
• Two 10-inch Quiet Flow™ sound attenuated diesel trash pumps
• Restoration of structural stability to the existing sewer pipe through CIPP, or cured-in-place-pipe liner

Although the winter offered the ideal situation for wastewater flows, extreme cold weather threatened to delay the project. Just two weeks prior to Sunbelt Rentals’ arrival, temperatures dropped to a record low -36 degrees F.

However, thanks to extensive planning, Sunbelt was prepared for the challenges of working in such a harsh climate. Although we weren’t able to utilize custom heat blankets due to manufacturer limitations, we engineered a more cost effective method to prevent freezing through the use of strategically placed electric heat tape on the pumps.

The Sunbelt team also hoarded the pumps, a practice common in Canada that involves enclosing equipment with insulated fabric to protect job sites from the environment. After a thorough check of all pumping equipment, operation of the bypass began.

"Careful planning was the key to avoiding problems. Pipes and pumps would have to be kept from freezing. Every detail had to be planned and scrutinized to mitigate any chance of failure.”
- Ladd Gould, Sunbelt Rentals National Strategic Account Manager

Weeks later, the Sunbelt Rentals crews noticed excessive groundwater filtration in the bypass excavation due to the ground thaw and snow melt from the boiler truck hoes and heat from the hoarded manifold. Despite the addition of pea gravel below the pipes, the attrition continued to worsen, eventually shifting the 40-foot manifold one foot. Our crew was able to recrib the piping, secure the manifold and shore up the slope, successfully averting a potential crisis.

Our complete turnkey services which included planning, coordination and skillful execution, earned industry recognition. Sunbelt Rentals was awarded the 2012 Project of the Year presented by the Northwest Chapter of the North American Society for Trenchless Technology and the Tunneling Association of Canada.

This project marked the first large sanitary sewer bypass pumping project of its kind in western Canada.