Niagara Street Pipe Assembly Vital Part of Regional Sewage Treatment Plant
By Robert Hawkes
The entire region owes a debt of gratitude to James Bay residents for accepting the inconvenience caused by the wastewater pipe assembly that has closed most of Niagara Street for the month of March. Bus routes were changed, Niagara Street residents could not park at their residences, and pedestrian routes to the area near Dallas were made longer. Emergency vehicle access to the area was possible at all times.
The regional wastewater treatment plant, now under construction, is located at McLoughlin Point in Esquimalt. Most of the wastewater from Victoria, Oak Bay, and Saanich will pass through a conveyance pipe under the harbour from Ogden Point to McLoughlin Point and, therefore, this is a vital part of the overall sewage treatment project.
The conveyance pipe has been assembled on Niagara Street this month. The length of pipe needed to go from Ogden Point to McLoughlin Point is 940 meters, and that is made up of 78 pipe sections, each 12.2 metres long (or about 40 feet). The pipe segments have been assembled on Niagara Street, with the sections welded together. The pipe is steel with a polyurethane liner. As well as welding, the interior weld joints are coated to enhance flow and provide additional protection for the pipe.
Starting last summer, a tunnel was drilled through rock under the harbour. At first a smaller lead shaft was drilled from Ogden Point to McLoughlin Point, and then drilling from both sides increased the diameter of the tunnel to make it large enough for the pipe (the pipe is 1.1 metres in diameter, or about 3.4 feet).
The most challenging part of the project occurs in the next little whilewith the pipe pull. Cranes will lift the pipe and direct it to the entrance of the harbour tunnel just off Dallas. That section of Dallas Street will be closed to traffic during this part of the work. The pipe pull will take about a week. To give a sense of how challenging the task is, the total weight of the 940 m of pipe is about 615 tons! The firms doing the work constructed three-dimensional models of the Niagara Street region to make sure that the clearances support the pipe pull operations.
The contractors have had an information tent set up near the James Bay Community School throughout the Niagara Street closure, and I asked representatives there why it was not possible to do the pipe pull in reverse - that is assemble the pipe at McLoughlin Point and then pull it to this side so that there would not be the huge inconvenience to Niagara Street residents. The answer was that there was not an area of sufficient length and flatness on the other side of the harbour.
The overall project is actually ahead of schedule. Originally the Niagara Street pipe assembly had been scheduled for June 2018. There will be another major disruption to the area when a conveyance pipe from Clover Point to Ogden Point is constructed along Dallas.
The sewage treatment plant is partly in response to federal sewage treatment regulations put into law in 2012 (and already implemented by the vast majority of municipalities in Canada). Phase one of those regulations require municipal sewage treatment systems be operational by 2020. Federal funding was provided to cover part of the costs.
The sewage plant will serve the municipalities of Victoria, Esquimalt, Saanich, Oak Bay, View Royal, Langford and Colwood, and the Esquimalt and Songhees Nations. The plant will have a capacity of treating just over 108 million litres a day.
As well as the conveyance systems to move wastewater to the facility, another conveyance system will move Class A biosolids to the solid waste treatment facility at the Hartland landfill.
The final approved project has a number of changes from the draft one circulated earlier. The setback of the plant from the coast has been increased, and a multi-level green roof has been added along with other changes to make the facility better match the nearby land. Also, the project now includes tertiary treatment (the original plan had just been primary and secondary sewage treatment), an important improvement for the marine ecosystem health.
The overall cost of the entire sewage treatment project is about $765 million. Of this, $120 million is from the federal Building Canada fund, $50 million from Green Infrastructure Fund and another $41 million from a federal residual treatment program. The province of British Columbia is providing $248 million for the project. The remaining $306 million, along with any excess costs, will fall to the residents of the Capital Regional District. The schedule has the commissioning of the plant to take place between fall 2019 and fall 2020.