Canadian Consulting Engineer
York Region’s “Big Pipe” pushes onEngineering
Work is proceeding on York Region's massive expansion to the York-Durham Sewage System in the Greater Toronto Area....
Work is proceeding on York Region’s massive expansion to the York-Durham Sewage System in the Greater Toronto Area. The project will see 40 kilometres of sewage pipe laid through the suburban areas of Richmond Hill and Markham, including threading through parts of the Oak Ridges Moraine. <br>
The York-Durham system serves a vast area of the GTA, collecting wastewater from areas as far west as Vaughan, as far north as Newmarket, and east into Pickering where it discharges its load into Lake Ontario at the Duffin Creek Wastewater Treatment Plant.
The expansion involves twinning some parts of the system, which was originally built in the 1970s and 1980s, and adding new lines and links to fill in the network. The total budget is currently $322 million (aside from the wastewater treatment plant) and consulting engineers are heavily involved. <br>
The expansions are facing fierce opposition by environmentalists, who nickname the project “The Big Pipe,” and fear it will only encourage more housing subdivisions on former rural and semi-rural land. One of the environmentalists’ chief concerns has been
the amount of dewatering necessary to construct the large deep gravity sewers along 16th Avenue, a component which is now in its second phase. Currently 20,000 litres per minute of groundwater is being pumped out of the aquifer in order for crews to install the 2.7-mm diameter pipe. People living in the area have been alarmed by a drop in their well levels, but York Region assures the public that aquifer level will return to normal eventually. In the meantime, the region has set up a $30 million-fund for environmental protection and to help local residents who have been affected.
At the heart of the system near the Yonge Street corridor is the “YDSS Interceptor” project in Richmond Hill. Ten different routes and construction methods were considered for this environmentally sensitive area. The route selected runs along 19th Avenue where the pipe can run directly below the road. In this section York Region has decided to use Earth Pressure Balance Machines for tunnelling because they involve less dewatering. Budgeted to cost $57 million, the YDSS Interceptor component is expected to go to tender in the spring. Engineering consultants involved are a consortium led by Earth Tech, including Brian Beattie & Associates, Michalski Nielsen Associations, Parish Geomorphic, Alston & Associates, Hatch Mott MacDonald and Thurber Engineering.
CH2M Hill and Earth Tech have been awarded a contract to design a $300-million expansion to the Duffin Water Treatment plant at Pickering, which needs to expand by 50% by 2010 to be able to accommodate the added flows. The York-Durham collector system involves no combined-sewers, so the waste is all from the rapidly expanding housing developments and population base of the area, currently at 91,000 people.<br>
Another important component of the system expansion is the new Bathurst Collector/Langstaff Trunk in the western section. It is partially under construction and amounts to 13.2 kilometres of pipe. <br>