Orleans Cumberland Collector Pumping Station
The city of Ottawa has contracted with local Doran Contractors Limited (Doran) to construct the Orleans Cumberland Collector Pumping Station and a diversion chamber at the Robert O. Pickard Environmental Centre. The new pumping station will help handle the sewage from the east end of the city.
Michael Denham, project manager at Doran, reports that the company broke ground on the $14 million project in June 2011, and the work is on schedule to be complete by July 2013. Major components of the project include two shafts 30 feet in diameter, dug 80 feet deep and connected by a 53-meter-long and 1.5-meter-diameter tunnel.
“This type of project is right up our alley,” says Denham of the work Doran completes. “We’re right on schedule. We wanted to have the two shafts poured and back up to grade by Christmas and that’s exactly where we are. So now we just have the building to build.”
The shafts were excavated using a slurry wall system. One shaft is a diversion chamber designed to tie in to a two-meter diameter surcharged sewer being fed by the east end of Ottawa. According to Denham, work was done on the shafts while the nearby sewer line remained live and under surcharged conditions.
The existing sewer flow had to be diverted while the new diversion chamber was constructed. A tunnel boring machine was lowered down the pump station shaft and drilled through to the diversion chamber shaft. Denham reports this was the trickiest part of the job. “There were some very stressful moments doing the live sewer tie in,” Denham says. “That’s out of the way and the project is running very well now.”
Rooted in Success
Doran, founded in 1896, is a successful local-owned and -operated company that forms part of the Taggart Group of Companies. Doran is the general contractor, construction management and design-build wing of Taggart Group of Companies, and has become a renowned general contractor in the Ottawa and Ontario region. Over the years, Doran has built many of Ottawa’s landmark buildings, structures and infrastructure projects, some of which include much of Ottawa’s Transitway as it exists today. The company has also successfully completed the Robert O’ Pickard Environmental Center Digester Expansion, the Centre Block Underground Services Building, the Plaza Bridge Rehabilitation, the East Market Condominiums, CBC Headquarters and the Royal Military College Dormitories.
Denham has been with the company for eight years. While he has experience in a variety of settings, Denham’s most recent jobs have been managing sewer-related projects. This particular project has been challenging because of the nearby live sewer line.
What helps Doran overcome challenging situations is the network of subcontractors used. “We manage the project and 99 percent of the work is subcontracted out,” says Denham.
For the pumping station – and similar projects of similar nature – the project owner had a list of prequalified general contractors, which in turn had to produce a list of its subcontractor team members. The teams were scrutinized and either approved or rejected to ensure the tender packages submitted were from Denham general contractors and that the teams had enough similar experience to complete the project successfully. According to Denham, only two general contractors managed to be prequalified for the pumping station project.
Part of a City-wide Plan
The new pumping station is part of Ottawa’s infrastructure master plan. A study projected that between 2006 and 2031, the population of the city will increase by 30 percent. With such a growth in population, the city anticipates a higher demand on its water and sewer systems among other things. The master plan is the city’s effort to prepare for that growth at the base level.
The Orleans Cumberland Collector Pumping Station is expected to improve the hydraulic grade line, avoid pipe sedimentation and provide additional pumping capacity. Infrastructure work in the city is planned through 2019.
Doran has been able to complete work on the pumping station with minimal impact to the surrounding neighborhood. According to Denham, not interrupting services, like sewer services, to residents is a major consideration with projects like this.
Now that the shafts are dug and connected, the most stressful part of the job is done for Doran. Denham reports that what is left to complete the contract is the pumping station building itself. Sticking with the schedule, Denham expects the Orleans Cumberland Collector Pumping Station to wrap up as scheduled and be in full use by summer 2013.