REHAB HONORABLE MENTION

Saskatoon Interceptor Trunk Sewer Rehabilitation

Constructed between 1912 and 1970, the City of Saskatoon’s Interceptor Trunk Sewer conveys wastewater from all areas of Saskatoon. The City completed a study of the trunk in 2006 to determine its current structural condition and formulate a rehabilitation program. Among the study’s findings was that the downstream portion of the trunk required rehabilitation. This section is an 84-in. reinforced concrete pipe, 1,007 ft in length. All of the city’s wastewater traverses this portion of the interceptor. The project included cleaning and CIPP lining, complete with a large temporary bypass. The City has never undertaken a bypass pumping project of this magnitude; this is the first sanitary sewer bypass pumping project of this magnitude in Western Canada. Due to the large diameter of the pipe and the high base flows through it 27,000 gpm, there was a high level of difficulty and risk associated with executing this project. Following a pre-qualification process and tendering of the project, the construction contract was awarded to Insituform. This project involved a challenging schedule, as well as working under cold weather conditions in which temperatures dropped as low as -37 F; during bypass system operation and lining, temperatures were as low as -2 F.

Project Owner: City of Saskatoon
Engineer: City of Saskatoon
Contractor: Insituform Technologies Ltd.

Pasco Water Main Repair

Pasco, Wash., had an issue: A 66-year-old, lead-joint, ductile iron pipe that carried drinking water to the city of 60,000 had developed cracks and needed rehabilitation. The situation was complicated because two 275-ft sections of the 12-in. pipe ran 8 ft under six sets of actively used railroad tracks. After five years of working around the deteriorated pipe, Michels Pipe Services, a division of Michels Corp., was contracted to structurally rehabilitate the pipe and return it to active use. The site was complicated. The Burlington-Northern tracks are critical to Pasco’s economy and the rails could not be taken out of service while the work was done.

Michels Pipe Services installed a NSF 61-approved Class IV fully structural Nordipipe liner. The liner was prepared at Michels’ Salem, Ore., facility and transported to the site overnight. A pressure vessel was used to invert the tube and it was cured with steam to a statically self-supporting pipe within a pipe meeting AWWA Class IV standards. Each installation took 12 hours. End seals were used to join the liner to the existing ductile iron pipe and after a 150 psi pressure test, the pipe was returned to service.

Project Owner: City of Pasco, Wash.
Engineer: Robert Blain
Contractor: Michels Pipe Services