A tunnel will one day link New Westminster to Surrey deep under the Mighty Fraser to provide drinking water for folks living on the south side of the river.
Metro Vancouver is in the early stages of planning for the Annacis water supply tunnel, which would be about four to five metres in diameter and will house a 2.5-metre steel water main that will be connected to the existing distribution system.
Contractors were recently at the Quay doing geotechnical testing as part of a drilling program along the proposed tunnel alignment.
“This project will have a design life of 100 years. We are looking at the growth in water demand to be fairly significant over that period of time frame,” said Frank Huber, director of major projects, management systems and utility services for Metro Vancouver. “While we certainly have enough capacity right now, we need to be looking ahead for future generations. That’s what this is doing. It’s part of our long-term planning.”
Huber said Metro Vancouver has done some conceptual work in the last couple of years to get a handle on the best location to build the tunnel and how to tie it in to the existing water system.
“We have just started the next phase of engineering called preliminary design. That will take about two years to complete. Then we go into detailed design. That will also take at least a year-and-a-half to complete,” Huber said. “So we wouldn’t be going to construction until probably early 2020. But again, these are early days still so these days are a bit fluid.”
While the depth of the Fraser River varies quite a bit, Huber said it’s about 30 metres in the area being considered for the tunnel. The tunnel would be located 50 to 70 metres below the top of the river.
“The purpose for it being as deep as we want it to be is we want to make sure that it’s seismically resistant,” Huber said. “Any marine crossings we are building these days, we want to make sure that they can ride out a major earthquake. If they fail, they take so many years to design and build that it would be very difficult for the whole region in a period like that.”
To get that deep under the river, Metro Vancouver will construct a shaft on the south side of the river in the area near South Fraser Perimeter Road and Grace Road. That vertical shaft will go down to the final elevation of the tunnel.
“Then we lower down a tunnel-boring machine, similar to the Port Mann tunnel that we are just finishing, and that machine will bore under the river for about 2.3 kilometres and it will connect with a shaft that will have been excavated on the north side in New Westminster near Royal Avenue and 11th Street,” Huber said.
The exact location of the New Westminster site has yet to be finalized, as Metro Vancouver is looking at a number of properties and hopes to purchase one of them.
“The way we have designed this is we would have the entry shaft on the Surrey side, where the property we are looking at is owned by the City of Surrey and is much more spacious and rural. That’s the larger site where the contractor would have his lay-down area for the tunnel-boring machine and equipment, versus on the north side in New West it’s a much smaller area. There, all we need to be able to do is build the shaft and have a crane and some minor ancillary equipment to allow people to go up and down,” Huber said. “It’s a much smaller footprint on the New West side than on the Surrey side.”
