Seymour-Capilano Water Filtration Plant, Canada

With a daily capacity of 1.8 billion litres, the new Seymour-Capilano water filtration plant seems destined to be something of a landmark facility when it finally comes on-stream towards the end of 2008.

Not only will it be Canada's largest – and one of the biggest of its kind in North America – but it will also host the world's largest ultraviolet disinfection facility, as well as showcasing a series of innovative features to maximise its energy efficiency. Extensive use is also being made of sustainable and environmental technologies in its design and construction.

In addition to the filtration and UV plants themselves, the project also includes a pumping station, an energy recovery facility and break head tank, an electrical substation, two 3.7m-diameter tunnels, extending just over 7km and new water storage clear-wells. An allied programme of work will provide a new water main and undertake a major upgrade to the Seymour Falls Dam to meet current seismic standards.

The project budget is around C$600m and has attracted partial external funding.

BACKGROUND – INCREASED DEMAND

Greater Vancouver's drinking water comes from reservoirs located in three watersheds – Seymour, Capilano and Coquitlam – with the Seymour and Capilano watersheds supplying some 70% of the region's drinking water.

The project was driven by tighter federal and provincial quality requirements and the regional medical health officers' demands for lower levels of turbidity, coupled with a predicted population increase of 800,000 over the next 20 years.

To meet these challenges – and the anticipated increase in demand – in 2001, the Greater Vancouver Regional District (GVRD) decided to build a filtration plant, the contract originally being a design-build-operate, public-private partnership (locally termed P3). However, after a massive public campaign, this contract was set aside to enable the new plant to remain in public hands.

THE PLANT

The facility – which is being built on an eight hectare site in the Lower Seymour Conservation Reserve – will treat water drawn from both Seymour and Capilano reservoirs. Water will arrive from Seymour, some 11km to the north, along the existing 2.3m-diameter main, while the new twin tunnels will convey Capilano water to and from the plant – the return arm being gravity-fed.

The plant design itself is largely conventional. Water from the two reservoirs will enter a rapid-mix head works, where coagulant will be added. From here it enters flocculation basins and is subjected to a slow mix process. The subsequent direct filtration phase will use a 2m deep filter dual-media bed consisting of anthracite and sand and from here the filtered water will enter the UV disinfection unit.

Flowing into treated water storage clear-wells, the pH will then be adjusted before the water enters the Capilano and Seymour distribution networks. UV disinfection was selected for the plant – using mercury vapour lamps installed inside quartz protective sleeves – principally because of its proven effectiveness against both giardia and cryptosporidium. However, although the new plant will use UV as its primary disinfection regime, secondary chlorination will remain a feature, to guarantee the safety of the potable water travelling through the municipal distribution systems.

SUSTAINABLE TECHNOLOGIES

With the plant itself being built in a conservation reserve, unsurprisingly the project has been planned in strict accord with the GVRD's Sustainable Region Initiative. As a result, it has drawn heavily on sustainable building, environmental technologies and best practices. These include the use of EcoSmart concrete, which reduces the greenhouse gas emissions of cement production and utilises industrial by-products such as fly ash to reduce the demand for landfill.

Green roof technologies are being incorporated into the roofs of the clear-wells and filtration plant and measures have been put in place to reduce storm water run-off. An energy recovery facility and the associated break head tank will recover energy from the water in the gravity-fed tunnel between Seymour and Capilano, reducing the pressure of the water prior to its reaching the distribution system. This recovered energy will be used to generate electricity, which will then either be used by the GVRD or sold to the local power company.

The plant will also make use of ground source energy to heat and cool the entire facility, maximise its use of daylight and natural ventilation, conserve both energy and water and, after the construction work is over, the site will be re-planted with appropriate native species.

KEY PLAYERS

The Greater Vancouver Regional District (GVRD) is the project sponsor. Emerson Process Management are to provide the plant's digital automation, with instrumentation and controls from RTS and control hardware being provided by Norpac. AMEC are to deliver the facility training program. The project has benefited from partial external funding from Canada-B.C. Infrastructure Grant Program (Filtration plant) and British Columbia's Local Government Grants Program (Capilano pumping station), while the GVRD member municipalities have provided residual funding, principally through bulk water sales.