City of Nanaimo - Pipe Bursting of the Millstone Sanitary Trunk Sewer

Consulting Engineers of British Columbia, Year 2000 Awards

Lieutenant-Governor's Award for Engineering Excellence

and

Award of Excellence - Infrastructure Category

Canadian Consulting Engineering - Awards 2000

Award of Excellence - Water Resources and Treatment Category

The City of Nanaimo successfully completed Canada’s most ambitious and largest upsizing pipe bursting project to date in 1999.

The degree of difficulty and innovation used in the Millstone Trunk Sewer Pipe Bursting Project was well recognized by CEBC and ACEC, and was also awarded the Rehabilitation Project of the Year for North America by Trenchless Technology Magazine.

Pipe Bursting Schematic

Dayton & Knight Ltd. was responsible for the detailed design and engineering services during construction for this unique program.

The project consisted of using pipe bursting trenchless technology to upsize approximately 4000 metres of 350 mm diameter asbestos-cement sanitary pipe to 650 mm diameter high-density, polyethylene pipe without excavating to remove the existing pipe.

Pipe bursting is an innovative pipe replacement technique where a bullet type expansion head is pulled through an existing pipe. The expansion head breaks apart the old pipe, expands the hole by pushing the pipe fragments and the surrounding soil outwards and drags the replacement pipe behind the expansion head into place simultaneously.

Excavation is not needed, except at the entry and exit pits for the pipe, which are located at manholes. Bypass pumping of all flows is required for the section of pipe being replaced.

Pipe Bursting in Progress

This trenchless construction approach greatly reduced the environmental impact in the sensitive Millstone River basin as well as disruptions on private properties, riparian zones and agricultural lands. Local BC Environmental and Department of Fisheries and Oceans Departments are so impressed with this innovative trenchless technology that they are supporting its application for future construction in environmentally sensitive areas.

Aerial View (Photo courtesy Bill Sims)

The work was completed about one month ahead of schedule, $600,000 under the $5.4 million budget, and $1.0 million less than if it had been undertaken by traditional open excavation and dewatering methods.

Aerial View (Photo courtesy Bill Sims)

For more information on this project please contact

Jack Lee, P.Eng. (jlee@dayton-knight.com)