September 25, 2006

Water Filtration

Largest tunnel project in decades

Jean Sorensen

Correspondent

Last year’s Port of Vancouver container strike by truckers and this year’s acute shortage of manpower in the construction industry have combined to stall the 2008 completion date of the new $600 million Seymour-Capilano Filtration Project (SCFP).

It is not expected to finish until 2009, say a spokesman for the Greater Vancouver Regional District (GVRD).

GVRD project liaison officer Steve Billington says that the new filtration plant will handle 1,800 mega-litres per day (making it one of the largest nu-builds in Canada) and receive water from the Seymour shed in 2008. It will not receive water from the Capilano reservoirs until 2009, when twin, connecting tunnels are finished, he says.

The SCFP tunnel portion, costing $140 million, consists of two vertical shafts (at each end) and twin, horizontal tunnels that are 7.1 km in length.

One tunnel will bring raw water from the Capilano reservoir into the new Seymour filtration station which will disgorge filtered water into a return tunnel to go back to Capilano junction where it will feed into the Greater Vancouver regional water supply. Except for a metal liner running for a kilometre on the Capilano side and 400 metres on the Seymour side, the tunnel rock will serve as the conveying device for the raw and filtered water, says GVRD senior project engineer Tom Morrison. Morrison says the project is expected to come in on budget.

“This is the largest tunnel project in B.C. for the past 20 years,” says Dean Brox, P.Eng., who worked on the project for engineering firm Hatch Mott MacDonald in Vancouver, which had the contract to design the project. He has also co-authored a number of papers on the project. (Brox and Morrison were part of a panel presenting information on the structure at the Tunneling Association of Canada’s national meeting held in Vancouver Sept. 18-20).

Other projects carried out in B.C. have been longer such as the Mount Macdonald Tunnel with east and west portals at Rogers Pass, which is a 14.6 km tunnel and considered the longest railway tunnel in North America. It was part of the CP Rail’s $600 million Rogers Pass expansion, which doubled train capacity and was completed in 1988.

On the Seymour side, an 11-metre diameter and 180-metre deep shaft was blasted out and completed in early November 2005.

The shaft is located across from the filtration plant. Additional excavation work at the base of the shaft was carried out until May 2006 to provide access for fresh air ventilation, electrical and mechanical services in the cavern where the crews will work at the base of the main shaft.

The residuals from boring the tunnels are being removed by small rail cars and lifted to the surface. The work to establish the rail yard and line was carried out this spring. Two tunnel boring machines (TBMs) with a 3.8 metre diameter and 1,260 kw are Robbins with 19-inch cutters on the cutting head, says Brox. They were shipped in from Ohio to Vancouver using 72 tractor-trailer loads.

This new generation of high-powered TBMs, with larger cutting discs than historically used on larger B.C. contracts, are 250 metres in length with trailing gear. The TBMs are owned by German-based Bilfinger Berger, which has established a Canadian entity (Bilfinger Berger Canada), to handle the contract. The larger components of the TBMs such as the cutting heads had to be lowered into the shaft and assembled underground.

Hatch Mott MacDonald

The Greater Vancouver Regional District is constructing the Seymour-Capilano water filtration project, which will improve the quality of drinking water in metropolitan Vancouver.

“The machines are expected to complete approximately 30 metres of tunneling a day,” says Brox, adding that one tunnel shaft has started (approximately 200 metres have been completed) and a second is just getting underway.

Morrison estimates that once the machines have reached full operating capacity (which they had not as yet), it will take eight to 10 months to complete the horizontal boring of the twin tunnels.

Problems have stalled the start of the tunneling. Morrison says Bilfinger Berger did not have a Canadian presence when the contract was won and had to begin from scratch assembling an office and work staff. Just as other construction sites have experienced labour shortages, there were problems finding employees.

Some were imported from Ontario’s mining industry while others had to be trained, Billington says. It was anticipated it would take 30 days to bring together a night shift, he says, but it took three months to find and train enough employees. “These are specialized skills not done in the Lower Mainland,” he says, adding that last year’s port strike also aggravated the situation. Needed containers were delayed in the strike.

The skilled crew that operates the large TBMs, though, is not a problem as they travel internationally working for Bilfinger Berger.

“The crew is mainly Filippino,” says Billington, adding that the smaller stature of the men are more suited to “shoe-closet” sized cab.

The Robbins TBM will progress west toward Capilano with the train cars removing the borings. Each l.5 metre push by a TBM will fill six Muhlhauser five cubic-metre rail cars.

Once the TBMs reach the point of the Capilano shafts, they will return to the Seymour side and be broken down for removal from the site.

The final Capilano twin shafts (four metres in diameter and 275 metres in length) are cut using raised boring, where a driven shaft is sunk to the tunnel level below and a cutting head attached to it. The shaft is turned from above the ground causing the head below to literally scour a path upward. Cut material falls to the ground where it is scooped into railcars and hauled to a dumping area in Seymour.

The material will be used in a variety of GVRD projects at later dates. The last few metres of the raised bore will be blasted away.

Billington said the decision to remove material from the Seymour side as opposed to the Capilano portal was made because some houses are only 25 metres away, while on the Seymour side they are 250 metres.

He said a $1 million sound buffering fence has been installed at the Seymour side to mitigate noise.

Hatch Mott MacDonald

Construction continues on the $600 million Seymour-Capilano Filtration Project (SCFP), which consists of two vertical shafts (at each end) and twin, horizontal tunnels 7.1 km in length.

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