Tackling the Niagara Escarpment for Grimsby, Ont.’s water future

A$20-million project to provide water security for the Grimsby, Ont. area and meet future population growth demands had to overcome the complexities and restrictions of building on the Niagara Escarpment.

Designed by WSP Canada Inc., the project is major enhancement of the Grimsby water distribution system which transports treated Lake Ontario water from the Grimsby Water Treatment Plant up the escarpment.

It includes the construction of a two-cell 15-millionmulticellular potable water storage reservoir on a 16-acre site on Park Road at the top of the escarpment, the installation of an approximately 850-metrelong, 500-mm back feed waterman along that road, and significant upgrades to the existing 3.41-millionreservoir and pumping station, about 800 metres south of where the new one is being built.

Construction by MississaugaRomag Contracting Ltd. started in February 2020, with staged infrastructure tie-ins to the existing distribution systems occurring this summer, and is expected to be completed by November.

Through a combination of reservoirs and high lift and booster pumping stations, the distribution system delivers potable water to Grimsby, the community of Beamsville in the Town of Lincoln and the West Lincoln community of Smithville— it is stored in an elevated tank.

But a lot has changed since the plant was commissioned in 1994 as the newest one owned operated by Niagara Region at that time, says regional project manager Gino Granola.

In a 2011 water and wastewater master servicing plan, a staff report warned the Grimsby system had insufficient water storage to meet 2031 demands. The town’s population is projected to reach 33,200 that year from its present level of 29,430 and the other communities are also growing, he says.

Of the 10 megalitres (ML) storage at the treatment plant, only 50 per cent is considerable to be available storage, due to constraints in “chlorine contact time” and other nearby communities cannot service the demands of the Grimsby water system, he says.

Additional floating storage is required in the Grimsby area in the event of emergencies such as fires and the 2011 staff report recommended the construction of a 15 ML reservoir to address the supply security issue. It also underlined the need for a second study to determine the best location, he says.

That process got underway a few years later with an environmental assessment which, in 2015, concluded the optimal location was the 16-acre site. Formerly agricultural land, it was ultimately purchased by the Region, says Granola.

In an ideal situation the new reservoir would be on the same site and same elevation as the old one. That wasn’t possible as the existing reservoir and pumping station are located mid-way up the Niagara Escarpment and increased protective measures for the escarpment ruled out an expansion, says WSP project manager Dean Whittaker.

Erecting the new structure 50 metres higher on top of the escarpment higher keeps it out the escarpment’s designated environmentally sensitive areas.

At the same time the new location came with more than a few complications, he adds.

“This 50-metre elevation difference posed unique challenges as the two reservoirs were meant to provide floating storage to service a single distribution system.”

Overcoming those challenges required a comprehensive set of measures, one of which is the installation of an automatically actuated reducing valve on the 500 mm diameter watermain, connecting the new and old reservoirs.

“By equipping the pressure reducing valve (PRV) with an automated pilot actuator, the downstream pressure reducing set-up can be modified remotely for increased control,” says Whittaker, explaining the remote control on the PRV is automatically set to produce a net zero differential operating level between the two reservoirs.

In order to maintain water freshness and a consistent chlorine residual throughout the Grimsby Distribution System, as well as that of the downstream Smithville one, the entire combined network has been designed as a single-pass flow-through system.

“The design measures are not exactly new technology. But are very specific to this project and the design took some thought,” says Whittaker, noting it took 18 months to complete and included water modelling exercises and several site visits.

From a construction perspective, the most critical phase will be the tie-ins to the existing distribution system. At the old reservoir a temporary bypass will be connected directly to the pumping station allowing the reservoir to go offline for approximately two to three months for the installation of process pipe and valve upgrades, “which will increase water circulation and ultimately improve water quality.”

A combination of drone technology and traditional survey methods are being used to document the project’s progress and ensure it is being built to specifications. Images taken by WSP’s drone survey crew, usually on a monthly basis, are overlaid with the engineering drawings to provide very precise three-dimensional details.