Launch Slideshow

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Building a dual-purpose water system

Building a dual-purpose water system

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    Distribution process serves dual purpose39° F water is drawn through three new intake pipes, treated at the Island filtration plant, and directed through an existing cross-harbor tunnel to the John Street pumping station. Prior to entering the drinking water supply, the water is sent through heat exchangers and thermal energy is transferred from the Enwave system to the city system. Water enters the city side of the heat exchangers at 40° F and leaves at 55° F, with 15° F transferred from the water on Enwave's side of the heat exchanger. Physical separation between Enwave's system and the city's system is maintained via heat exchangers that are designed to facilitate the transfer of energy, not water. A single source of water provides coldness for Enwave's system and drinking water for the city. Source: Enwave

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    Three 63-inch outside diameter HDPE pipes stretch 3 miles out into Lake Ontario to draw 39° F water from 275 feet down. Source: Enwave

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    Toronto's water passes through many stages1. Three intake pipes draw 39° F water from Lake Ontario at a depth of 275 feet. The water is then filtered and treated for the city's potable water supply.2. At the energy transfer station (ETS), the icy cold water is used to cool Enwave's closed chilled water supply loop through pairs of heat exchangers. The ETS is adjacent to the city of Toronto's John Street pumping station.3. Chilled water can bypass the cooling plant and continue to the customer building. If necessary, water can be further chilled by two, 4700 ton, steam-driven, centrifugal chillers.4. Heat exchangers at the customer building cool the internal building loop, providing chilled water for the building cooling system. Source: Enwave

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    One of the 3-mile, 63-inch pipes is towed out into Lake Ontario. The pipe actually traveled more than 290 miles from the extruding plant to the assembly site to the Toronto lakefront. Photo: Enwave

Transporting and Installing the Pipe

The pipe was extruded at the KWH Pipe plant in Huntsville, Ontario, 129 miles north of Toronto. From there it was shipped in sections nearly 185 miles to Belleville, Ontario, for assembly. Belleville provided the nearest “sheltered area that was large enough to store and fuse the pipe,” said Jeff Starchuck, project engineer of the Marine Division of McNally Construction of Hamilton, Ontario. “We also needed a fairly large, secure, and sheltered water lot to store the pipe over the winter. Recreational boater traffic on Lake Ontario being what it is, it's difficult to find an area out of the way of traffic and with sufficient shelter that is near Toronto.

“The first year we couldn't get started until early June and we couldn't carry on after November due to the build up of ice on the lake,” said Starchuck. “So we sunk the pipes below the ice line in water off Belleville and brought them up again in the spring. Pipe sections were fused together to create nine 1 -mile lengths, plus five shorter lengths varying from 182 to 330 feet long. We also installed the concrete collars and ductile iron stiffening rings in Belleville. Then we towed the mile plus pipe lengths 109 miles to the Toronto lakefront.”

“It was the longest pipe ever towed on Lake Ontario,” said Loughborough.

Saving Chiller Costs

“There are real savings in not having to replace 37-year-old chillers,” said Loughborough. “The first of the three Toronto Dominion Centre towers—which soar to 54 floors—was under construction in 1964. The chillers haven't been replaced since then. That's 37 years since the building was opened and 25 years is the normally quoted life span for a chiller.”

Andrew McCallin, vice president of the Toronto-based Oxford Properties Group agrees that the upfront savings lie in not having to replace chillers. McCallin figures he has already saved $580,000 by not having to replace chillers at One University Avenue. “That's a pretty compelling reason right there,” he said.

At the 1.6 million square foot Royal Bank Plaza the replacement of 26-year-old chillers would “have costs us millions and we would have had to take the building apart and use helicopters to get the chillers off the roof,” said McCallin.

“Getting rid of chillers also allows us to rent out some prime penthouse space. At One University, the extra 1500 square feet translates into another $30,000 of rentable space per year.” McCallin also said that by signing a 20-year contract with Enwave, he has a program for further savings as energy prices increase.

Although predictions of two-thirds savings in water treatment chemicals have been suggested, “any potential chemical savings will be determined through continuous testing,” said Gordon Mitchell, senior engineer with Toronto's Works & Emergency Water and Wastewater Services Division. “What we have is an excellent clear water source; it's a great added benefit to the city.”

Warne is the owner of Warne Marketing + Communications, Toronto.