Region of Halton’s Oakville Water Purification Plant will provide improved water quality

A Construction is well underway for the $25 million upgrade of the Regional Municipality of Halton’s Oakville Water Purification Plant. The Oakville plant treats 120 million litres of Lake Ontario water daily. A conventional water treatment plant, the facility employs coagulation, flocculation, sedimentation, and dual-media filtration with anthracite over sand for additional particulate removal. The plant also uses a gas chlorination system to provide zebra mussel control, taste and odour control, and primary and secondary disinfection.

To improve the pre-treatment process and provide better taste and odour control, the Region retained Associated Engineering to provide engineering services for the plant upgrade. The upgrade strategy included a retrofit design and construction approach without expanding the existing treatment and production capacities. The Region wanted to stage construction activities to maintain overall plant production above 50 percent during the low water demand period, between September and April, and at 100 percent during the high water demand period between May and August. Associated Engineering’s retrofit design addressed the various design criteria within the existing footprint of the Oakville plant and considered the construction restrictions.

The plant upgrade includes:

• Improving the existing low-lift and high-lift pumping stations
• Converting the existing two sedimentation basins into two, parallel process trains comprising high-rate, ballastedflocculation and ozonation
• Converting the existing three-staged tapered-flocculation basins into multiple, self-contained chemical storage areas for the chemical systems required by the new treatment process
• Providing filter-to-waste
• Constructing a new, on-site treated water reservoir
• Converting the existing process wastewater treatment system to a new gravity thickener system.

The pretreatment process will employ Actiflo®, a proprietary process that uses microsand to “ballast” flocs, and thus assist sedimentation. Pretreatment is followed by intermediate ozonation for primary disinfection and taste and odour control using liquid oxygen as the feed-gas and a side-stream ozone injection system for mass transfer of ozone into solution. The new chemical systems include:

• Calcium thiosulphate for chlorine and ozone residual quenching
• Sulphuric acid for pH suppression
• Alum for pre-treatment
• Dry polymer for optimizing the pre-treatment strategy
• Hydrogen peroxide for advanced taste and odour control
• Sodium hydroxide for pH adjustment prior to distribution
• Fluoride for preventative dental care
• Chlorine for zebra mussel control, secondary disinfection, and as a back-up primary disinfection strategy and
• Liquid polymer for optimization of the process wastewater treatment system.
• The upgraded plant will provide improved water quality and meet future water quality guidelines.

“Construction is proceeding well,” reports resident inspector, Salma Dharsee. “The first phase of upgrades, including a new treated water reservoir, gravity thickener, Train 1 of the Actiflo® process, and ancillary systems, will be commissioned in May 2006. The filter-towaste upgrades and Train 1 ozone will be commissioned later in 2006. The remaining upgrades will be commissioned by June 2007.”

One key factor in facilitating this project was the partnering between the Region, Associated Engineering, and King City Group (the contractor). Ron Rae, Halton Region Project Manager says, “The partnering atmosphere here is very good. We’re working well with the consultant and the contractor. Associated Engineering has been very cooperative through the design and construction phase. [They are] very open minded about the opinions of our staff. They’re willing to embrace good ideas that haven’t come from within their organization.” Rae adds that this partnering attitude extends to the local area residents, who have been involved in providing input to certain design components throughout the design process. Rae explains that it’s “part of the quality that we’re going after for the citizens at home.”

Staff from across Associated Engineering have participated in the project. Key Associated Engineering staff include Elia Edwards (Project Manager), Fred Albanese (Construction Project Manager), Mark Belanger, Derek Blakemore, Bill Chisholm, Shane Cook, Iva Danilovic, Simeon Dee, Sam De Rose, Salma Dharsee, Frank Dolling, Dusan Fil, Bill Harvey, Jasna Halilovic, Dale Harrison, Jerry Helfrich, Vanja Jovic, Austin Suriam, Caroline Korn, Alex Leong, Mike Liszega, Charles McLeod, Amanda Odsen, Les Pickard, Rebecca Pringlemeir, Tony Raposo, Paula Steel, Wendell Thiessen, Ian Wright, and Joe Wyszomirski.