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Keeping The Sewer Running In Saskatoon
“Significant research went into the winterizing of the 10- and 18-inch Quiet Flow pumps that were slated for the project,” Gould explained. “First Sunbelt identified the key components of the pumps that would require heat to reduce the possibility of freezing -- the priming tank, check valve and volute, the casing that receives the fluid being pumped by the impeller.”
Next, heating options were considered.
“Sunbelt’s first choice was custom heat blankets,” he said, “but the manufacturer could not deliver within the required timeframe. As a backup choice, which turned into a significantly more cost effective alternative, we utilized electric heat tape strategically placed in those critical areas. The heat tapes were AC powered so a generator and power distribution was factored into the bid.”
Crew members had necessary protective equipment and cold-weather gear.
Site preparation began in December 2011, with Insituform’s earthwork subcontractor, Hamm Construction Ltd., beginning construction of the suction pit and other site work to accommodate the CIPP liner installation. Hamm constructed the excavation and cut five suction access ports into the top of the 84-inch sewer to greatly reduce the bypass static suction lift. Hamm also cored the discharge points into the influent channel at the treatment plant for the three 18-inch bypass discharge lines.
Equipment put in place included six 18-inch Quiet Flow pumps. “Three of the 18-inch pumps were required to maintain the 36.5 million gallons per day (mgd) specified by the city of Saskatoon,” said Gould. “Two additional pumps were tied in as backup providing 66 percent of bypass redundancy. Because of the remoteness of the project, an additional 18-inch pump was placed just out of the bypass system in the event of a total catastrophic pump failure.”
The five pumps were tied into a large, 40-foot-long manifold containing five,18-inch ports with knife gate valves for the bypass pumps, and three 18-inch ports with valves for the three 1,500-foot, 18-inch HDPE discharge lines. Bypass flow was discharged into the headworks of the Saskatoon Waste Water Treatment Plant.
Routes of bypass lines often complicate their construction and operation, but the Saskatoon project location gave personnel a break.