Glenmore & Bearspaw, Canada

Scheduled for completion in 2010, the seven year programme of upgrades at Calgary's two water treatment plants – Bearspaw and Glenmore – will enable the city to meet the needs of its projected population to 2025 and beyond.

The project involves improvements to the pre-treatment, filtration and chemical systems at both plants, together with upgrading residuals handling. At the Bearspaw WTP, the programme also includes the addition of ultra-violet disinfection, while at Glenmore the liquid chlorine and de-chlorination systems, taste and odour controls are also to be modernised and upgraded.

The project cost is C$300m; Bearspaw accounts for C$170m of the budget, with the work at Glenmore taking up the remaining C$130m.

BACKGROUND

The two main drivers on the project were the increasingly stringent federal and provincial Canadian regulatory standards coupled with the area's rising population, making an upgrade to the existing facilities inevitable. In addition, the city is committed to achieving a policy of zero discharge into the Elbow and Bow rivers by 2010, with waste streams to be treated and recycled on-site and residual solids removed to landfill.

The Glenmore facility – located on the Elbow River – was originally constructed in 1933 and was subsequently expanded twice, in 1957 and then again in 1965. Set beside the Bow River, Bearspaw, the city's second WTP, was built in 1972 – seven years after Glenmore's second expansion – and was itself last extended in 1984.

High turbidity during spring runoff had historically been a particular problem for both plants, with levels in excess of 1000 NTU often causing a temporary overload of the sedimentation basins and filters, forcing the reduction of treatment capacity to preserve drinking water quality.

Between 2001 and 2003, a comprehensive review of the water supply infrastructure determined that extensive work was needed at both plants to meet future needs. The seven-year scheme of upgrades began with the provision of a new sodium bisulphite de-chlorination facility and the installation of potassium permanganate oxidation at Glenmore while at Bearspaw improvements were made to the residuals and filter-to-waste systems.

BEARSPAW PLANT UPGRADES

Work at the Bearspaw plant comprises six elements – residuals treatment facility, filter-to-waste-recycling system, potassium permanganate dosing, pre-treatment facility, filter upgrades and UV disinfection – and has progressed well towards completion.

The residuals treatment facility, which entered service in 2007, will significantly enhance the treatment of waste streams from the treatment process. Clarified water from the waste is recycled to the pre-treatment phase, where solids are dewatered by centrifuge before being shipped off to landfill.

A new de-chlorination facility will avoid the possible need to discharge chlorinated water into the river in the event of an emergency.

The new potassium permanganate system provides an alternative to chlorination prior to pre-treatment, oxidising raw water compounds and helping overcome taste and odour problems while filter upgrades are underway to improve both backwash efficiency and performance. The provision of the plant's UV disinfection system is scheduled to begin in 2009, with final completion expected in 2010.

GLENMORE UPGRADES

Glenmore's upgrade encompasses eight components, five of which – residuals treatment facility, filter-to-waste-recycling system, potassium permanganate system, pre-treatment facility and filter upgrades – it shares in common with Bearspaw. The remaining project elements at Glenmore call for treatment stages employing sodium bisulphite, sodium hypochlorite and powdered activated carbon.

Installing both sodium bisulphite and sodium hypochlorite systems at the plant is principally to improve employee safety and enhance environmental protection, by removing the on-site need for sulphur dioxide and chlorine gases respectively.

The final part of the planned scheme – the powdered activated carbon system, which is due to enter service in late 2009 – has been selected to complement potassium permanganate dosing as a further method to deal with the taste and odour issues specific to Glenmore water.

Both plants have adopted the same solution to the turbidity problem, using sand ballasted clarification – opting for Veolia's Actiflo system, based on its high settling rate and compact footprint. Microsand acts as a seed for floc formation, simultaneously enhancing flocculation while adding ballast to encourage fast settlement, leading to a turbidity removal efficiency, which typically exceeds 90%.

Bearspaw has six clarifiers installed, with a total capacity of 586,000m³/d, while Glenmore will be equipped in two phases, the first installing four units with a capacity of 400,000m³/d, followed by two more to bring this up to an eventual 550,000m³/d. These systems – part of the new pre-treatment facilities – will effectively remove turbidity and organics prior to the filtration process.

KEY PLAYERS

The plants are owned and operated by the City of Calgary. The main contractor on the upgrade project is PCL Construction, with Associated Engineering acting as the principal consultant. Veolia provided the clarifier technology, with John Meunier supplying the clarifiers to the project. The City also works with groups such as the Elbow River Partnership and the Bow River Basin Council to protect and restore the watersheds and ensure the high quality of the raw water sources.

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