New water tanks help Saint John deliver abundant and clean water

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Loch Lomond Drinking Water Treatment Facility
Overview of the Loch Lomond Drinking Water Treatment Facility. North America Construction (1993) Ltd.

By Jessica Gregory

Residents on the east side of Saint John, New Brunswick, were all too familiar with boil water orders. For decades, the city drew water from Latimer Lake and chlorinated and pumped it directly to the distribution system. This meant that even the smallest issue with the chlorination process would necessitate the issuance of a boil order. Events as simple as “bad weather” could stir up sediment in Lake Latimer and cause significant problems.

“Flow was everything because we didn’t have water in reserve,” says Dean Price, project manager for the City of Saint John. “When your only source becomes contaminated, you have no other option but to warn people, and they become the last line of defence, which isn’t an ideal situation.”

In 2013, the City of Saint John Common Council launched the “Saint John Safe Clean Drinking Water Project”, the largest municipal infrastructure project in New Brunswick. The project was jointly funded by the Province of New Brunswick, Infrastructure Canada, and a group of private equity partners, including Acciona, Brookfield, and North America Construction.

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Engineering firm CBCL was retained to develop the scope of work and conceptual design, and produce preliminary design drawings for the request for proposal. After a full review of the project, Port City Water Partners was awarded the contract for the design, build, and finance. They will operate and maintain the new facility for the next 30 years. This type of agreement, called “Design-Build-Finance-Operate-Maintain” or DBFOM, is an increasingly popular method of building water and energy infrastructure, as it transfers most of the risk to the private sector.

Part of this project included building the Loch Lomond Drinking Water Treatment Facility to service Saint John residents. Water quality from the facility is significantly improved compared to the water quality from the former Latimer Lake Chlorination Facility. The new facility added several additional filtration steps to deliver drinking water that exceeds provincial and national standards. These include a dissolved air flotation process, advanced filtration, chlorination, disinfection and pH correction.

Considering the scope of the project, staying on budget and completing it on time were two critical components in its success. With system upgrades, including improvements to the surrounding watershed, water storage, pumping stations and transmission system, and the replacement and rehabilitation of water pipes, the project cost topped out around $228 million.

There have been 26 km of transmission system infrastructure improvements, including upgraded distribution mains. Planning began back in 2013, but actual construction of the new facility started in 2016 and reached substantial completion in June 2019. At this time, the Loch Lomond Facility was operating and supplying water to residents on the eastern side of Saint John.

Since the facility has gone into service, ongoing testing by the provincial departments of health and environment and local government monitoring confirms the system is providing the highest quality water for the area. As the facility was being brought online, the pH level was gradually adjusted and orthophosphate was introduced to prohibit corrosion.

The facility is capable of producing up to 75 million litres of clean drinking water per day. A 33 million-litre storage system, anchored by three 11 million-litre Aquastore© tanks was constructed by Greatario Engineered Storage Systems, for the Loch Lomond Drinking Water Treatment Facility.

“Since this was a design-build-operate project, we had a lot of discussion about how to spec the tanks to get the greatest return on investment and security of supply,” Price said about the choice in storage systems. “The investors wanted a storage solution that would be low maintenance for the 30 years that they’re operating the facility.”

The tanks are known for their adaptability and can be expanded to accommodate future flow or capacity requirements by adding additional panels. Owners consistently comment on the ease of connecting pipes and attaching launders, weirs and other components.

In conjunction with engineers from Wood PLC, the team designed the storage tanks to optimize performance. Consideration of the tank dimensions and additional accessories, as well as tank layout and positioning, helped during this part of the design phase.

“We set the reservoir bottom plate elevations, spaced the tanks to accommodate the inlet/outlet piping and set tank dimensions to achieve the required storage volumes,” says Brandon Turcotte, senior program manager at Wood. “As a result, three tanks were required rather than four, less bedrock excavation was needed, and the tank footprint was optimized.”

Storage tank footprint is often a significant consideration for utility operators, especially when space is limited. While construction of concrete and steel tanks often requires cranes and heavy equipment, Greatario-built tanks utilize a series of mechanical jacks that take up very little space.

Tanks are built from the top down on the ground. The top ring of panels is assembled first, then lifted to make room for the next ring, and so on. Heavy machinery and cranes aren’t necessary, even when building tanks to store 11 million litres of water. The glass-fused-to-steel tanks met technical specifications for longevity, size, liquid level capability, and height requirements.

The project gained attention around the country because of its unique funding source and the sheer scope of the undertaking. In 2017, it was recognized for its innovation and excellence with the Silver Award from the Canadian Council for Public-Private Partnerships. Then in 2018, it was awarded “Project of the Year” by the Atlantic Canada Water & Wastewater Association.

More recently, some residents on the west side of Saint John were brought online with the new Loch Lomond facility. Previously, they were serviced by the South Bay Wellfield. There, three large wells had been drilled and pumped water to a local treatment plant. Due to the depth of the wells, the water quality was naturally filtered and required little processing before delivery.

However, a lower than expected yield at the wellfield had caused the water level to drop below the nearby Bay of Fundy sea level, allowing seawater to seep in and contaminate the supply.

The switch has been successful in proving the new facility and increased storage can support additional demand.

Jessica Gregory is with Greatario Engineered Storage Systems. Email: jgregory@greatario.com

Read the full article in ES&E Magazine’s June/July issue below.

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