Construction on the Port Mann Water Supply Tunnel is nearing completion. In late June the tunnel boring for the project was completed, and the tunnel boring machine extracted from the access shaft on the north side of the Fraser River. Now crews are installing the steel pipe which will line the one kilometer long tunnel. When completed, the water main will more than double the current water supply capacity of the existing main and service the growing Metro Vancouver communities south of the Fraser. Tim Langmaid, the project manager for Hatch Mott MacDonald took us underground, for an up-close look at the final stages of the work.
“We are just about to drop into the south shaft of the Port Mann tunnel,” says Langmaid, as the crane basket begins its descent to the bottom of the 50 metre shaft, located on the south side of the Fraser River. “The water main will come up through the shaft and then go through a valve chamber that’s built onto the side of this shaft and that will be what supplies water to Surrey and other areas in the Fraser Valley.”
The water main will more than double the current water supply capacity of the existing main and service the growing Metro Vancouver communities south of the Fraser.
“Mining for the tunnel started in February 2014,” says Langmaid. “And we finally finished in the summer of 2015.”
In late June 2015, the tunnel boring for the project was completed, and the tunnel boring machine extracted from the access shaft on the north side of the Fraser River. As the tunnel boring machine progressed northward under the Fraser River, it also installed the concrete rings that support and protect the water main that will carry water to the Surrey side. A total of one thousand ring sections line the one kilometer tunnel connecting the north and south shafts. Tim takes us for a closer look.
“So we’ve come inside the Port Mann Tunnel now, to take a closer look at the concrete rings that make up the tunnel. These rings were built by the tunnel boring machine as the tunnel was excavated. And each ring is made up of six concrete segments. You can also see that the joints in the tunnel don’t quite line up. And this is designed specifically to give us the strongest structure possible. It’s very much like building a brick wall.”
Now crews are installing the steel pipe which will line the one kilometer long tunnel. Tim takes us further down the tunnel, where the work is being done.
“So we have come further into the tunnel now, so we can look at the steel liner which is being installed, which will eventually transport the water through the tunnel into Surrey. You can see here the gap between the steel liners for the tunnel and tunnel liner itself. This gap is about 40 cm and eventually we will fill this void with cement grout to hold the tunnel liners securely in the tunnel. The steel pipes which make up the liner are in approximately 9 metre lengths and each of these is welded together underground.”
“We’ve nearly finished installing all of the steel liner pipe into the tunnel,” adds Langmaid. “Once that work is complete we will need to grout those pipes in place and then we will need to install the pipes that come up the shaft and we still have to build the south valve chamber on the Surrey side of the project.”
The Port Mann Water Supply Tunnel will be commissioned in late 2016.
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