AWWA ACE62955

The City of Calgary's Bearspaw Water Treatment Plant is presently being upgraded to increase capacity from 420 million liters per day (ML/d) to 550 ML/d, and to enable it to meet increasingly stringent treated water quality and environmental standards. One of the major components of this upgrade is a new Residuals Treatment Facility (RTF) that will protect the environment by recycling all the major process waste streams, rather than discharging them to the Bow River. A major benefit of this initiative is that it will allow the City to optimize use of their existing surface water allocation from the Bow River Basin. The new 54 ML/d Bearspaw Residuals Treatment Facility (RTF) manages pretreatment clarifier waste, filter backwash waste, filter-to-waste, and process overflows. The residuals treatment process includes flow equalization, thickening, and dewatering. Filter backwash waste and clarifier waste sludge are flow equalized in the equalization tanks, and gravity fed to clarifier thickeners. Clarified effluent from the thickeners will be recycled to the head of a new ballasted-flocculation pretreatment process, while underflow sludge will be dewatered using centrifuges. The Residuals Treatment Facility also includes a pump station to recycle filter-to-waste flow to the head of the main plant process for re-processing. Due to the magnitude of the project, and a tight regulatory deadline, the City chose to employ a Construction Manager for project implementation. This allowed the design to be phased, and construction to start six months sooner than if a conventional design-bid- build project delivery method had been used. There were a total of seven equipment procurement packages and three major construction tenders produced for the project. This leading edge project will be the first of its type in Alberta, Canada. The RTF will be commissioned in 2006, and full recycling will commence in 2007 once construction of the new Pretreatment Facility is completed. Includes tables, figures.