City of Calgary Water Services

Special treatment┬áUpgrades to CalgaryÔÇÖs water treatment plants are well under way using the construction management approach, Gary Toushek discovers.  Unlike most large cities in Canada, which are subdivided into municipal districts, Calgary, Alberta, has a single municipal administration for its roughly one million people, and it supplies potable water to the city as well as some neighboring municipalities in the region. The city is also unique in that it has two water treatment plants located on two different water sources: the Bearspaw treatment plant is on the Bow River, and the Glenmore plant is on the Elbow River. A comprehensive review in 2001ÔÇô02 determined that both plants required extensive upgrading, and in late 2003 Calgary entered into a three-way construction partnership arrangement with consultancy firm Associated Engineering and contractor PCL Construction Management Inc. ÔÇ£The city thought it was a good idea to establish this relationship for a continuing process of contracting and design, since the upgrade program was over a seven-year period,ÔÇØ says Steve Dold, leader for project engineering, Glenmore water resources and infrastructure delivery, who manages a staff of 17 and is responsible for engineering and construction upgrades for both treatment plants as well as 40 secondary stations.The Bearspaw upgrade began in early 2004. ÔÇ£We constructed a new pre-treatment facility that uses ActifloÔÇÖs sand-ballasted flocculation, a new process for us,ÔÇØ says Dold, ÔÇ£and Bearspaw is the largest plant in North America to apply it.┬áWe used a conventional flocculation sedimentation process followed by sand anthracite multimedia filters, then chlorine disinfection with potable water distribution to the city. Our source is a river in which conditions can vary greatly, especially during runoff, and the Actiflo process responds more quickly [20 minutes] than conventional sedimentation [6 hours].ÔÇØ The Actiflo system was provided by John Meunier Inc., which engineers and designs water treatment equipment. Also completed at Bearspaw is the residuals treatment facility, which treats backwash and pre-treatment waste streams, so all removed sediments and solids are treated and the clarified water is recycled; the previous practice was discharging it into the river. The Bow River is a world-renowned trout fishery, and the City is committed to protecting this resource. CalgaryÔÇÖs current ÔÇ£zero dischargeÔÇØ approach sets the tone for environmental stewardship in the handling of treatment plant residuals; solids are dewatered by centrifuge and sent to a landfill. ÔÇ£The amount of raw water pumped and withdrawn from rivers has become an issue of discussion throughout the province, and this process reduces that amount by about 10 percent by recycling,ÔÇØ Dold says. ÔÇ£WeÔÇÖre actually licensed for the amount of water we can withdraw from the two rivers.ÔÇØThe other major upgrade at Bearspaw was to the filter plant. The previous system layered anthracite, sand and gravel.┬áBy installing a new stainless steel underdrain system, gravel is eliminated, and the sand and anthracite layers are improved, greatly enhancing filtering performance and capacity. ÔÇ£So this upgrade program has met three major objectives: the capacity is increased, there is a higher standard of treatment in terms of more stringent provincial guidelines for potable water quality, and the environmental and safety aspects of virtually eliminating discharges back to the river are satisfied. Process waste discharge is reduced to zero under normal operating conditions,ÔÇØ explains Dold.At the Glenmore treatment plant a sodium hypochlorite facility has been installed. ÔÇ£A number of municipalities are adopting on-site generation of sodium hypochlorite, which is similar to household-strength bleach, and we use a weak concentration,ÔÇØ Dold says. ÔÇ£WeÔÇÖre required to use chlorine disinfection in potable water by regulation. Previously, we had a gas chlorine system, but we had limited ability to deal with any occurrence of a leak, so weÔÇÖve gone to the on-site liquid generation to satisfy workplace safety issues. ThereÔÇÖs always a danger in transporting gas, and Glenmore is situated near the center of the city. Also, our operation and maintenance staffs are based at Glenmore, so it was important to change that system.ÔÇØ TheyÔÇÖre looking at adding ultraviolet disinfection to the system; itÔÇÖs a tool that adds another buffer of protection, in order to combat bacteria and viruses, particularly parasites such as cryptosporidium. Dold estimates that the construction partnership has completed about two-thirds of the upgrade program, slated for completion in early 2011. ÔÇ£When Glenmore is complete, weÔÇÖll proceed with implementing UV at the Bearspaw plant, as well as sodium hypochlorite.ÔÇØDold notes the challenge of upgrading plants while in operation. ÔÇ£We canÔÇÖt upgrade both treatments plants simultaneously, since we have to manage a continuous supply of treated water to the city, so shutdowns and tie-in work are planned well in advance to be as brief as possible. We pick a time of year when the demand is lower, but the construction must continue, so itÔÇÖs a balancing act that weÔÇÖre managing well.ÔÇØ Dold believes that one of the benefits of the construction management partnership with PCL and Associated Engineering is ÔÇ£the teamÔÇÖs ability to coordinate and make sure we donÔÇÖt adversely affect our operations or the water supply. We went through some growing pains during the formation of the partnership, so we all had to learn and struggle a bit initially. ItÔÇÖs a different approach compared to our traditional bid-design-build process, in terms of procurement, engineering and management, but weÔÇÖve kept the entire team together; itÔÇÖs quite stable and weÔÇÖre seeing obvious benefits in the latter half of the program. We remember the lessons we learned on Bearspaw, and itÔÇÖs allowed us to plan better for Glenmore and be more flexible.ÔÇØOverall, the construction marketÔÇÖs ÔÇ£fluctuationsÔÇØ have affected this project in a number of aspects. The previous construction boom in Calgary had been a major challenge. ÔÇ£Before this current economic downturn, we had to deal with an escalating oil and gas industry, which tied up a lot of the skilled labor force and gave us high fuel prices and increased material costs. But we worked through all that, and now weÔÇÖre seeing the big decline in demand for those areas, so the final third of the upgrade should go smoothly and less expensively.ÔÇØ Calgary has an extensive water conservation initiative thatÔÇÖs gotten response from consumers and businesses, and the result is a consistent, predictable demand for water despite the population increasing by up to 35,000 residents per year. A decade ago, 20 percent of residences were metered; today itÔÇÖs closer to 90 percent. An ad campaign aimed at the public has emphasized low-flow water fixtures and low-flush toilets. The ÔÇ£hot topicÔÇØ challenges for the cityÔÇÖs water services department under discussion at the moment, says Dold, are managing growth and demand on the water supply and maintaining watersheds for the future.  ÔÇô Editorial research by Richard Halfhide┬á