Trenchless Technology

Fall Canada 2018

Trenchless Technology is the premier communications vehicle for the trenchless industry. Through our multiple platforms, readers receive insights into the trenchless industry, as well as keep connected to the latest news, products and projects.

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32 T R E N C H L E S S T EC H N O LO GY C A N A DA FA L L 2018 I N 2010, 2013 A N D 2017, there were three major floods in the Town of Cobourg , Ontario. The most recent saw 50- to 70-mm of rainfall across a three-day span. Some streets had to be closed, rendered unusable by the flooding . Cobourg was proactive in advance of these floods, conducting inflow and infiltration flow studies in 2005 and 2006. The studies aimed to de- termine how much sewer capacity their manholes were costing them annually. The low-lying areas located near creeks, swamps and other water- ways — the areas that were targeted in their flow studies — were the most strongly impacted. The studies gave the Town an idea of the manholes that needed to be re- paired, relined or replaced entirely. Town leaders conducted tests in dif- ferent inflow and infiltration- sensi- tive areas in the Town and found two manhole locations in particular, lo - cated in swamp areas, that were per- fect candidates for determining how much inflow and infiltration comes through and around their frame and covers. Here's what they were able to re- solve: the only thing preventing in- flow and infiltration were the dead leaves around the existing manhole frame and covers and in the holes of the covers themselves. Because sur- face inflow is easier and less expen- sive to remedy than infiltration that occurs underground through pipe joint , crack leaks, and root intrusions, the flow study was an excellent op - portunity for the town The Town discovered another issue through these flow studies: as the sea- son transitions from winter to spring , meltwater significantly increases the amount of inflow and infiltration in their sewer systems. When the weather gets warmer towards the end of winter, the snow and ice melt , causing an influx in groundwater that needs to go some- where. Because snow is often plowed into the middle of cul -de- sacs, these were some of the areas most affected by meltwater. Although some meltwater will find its way into storm systems, some will inevitably run into the sanitary sewer systems throughout the mu- nicipality. Once this happens, the extraneous water will then be sent to the wastewater treatment plant . Each treatment plant has a rated ca- pacity for how many cubic metres it is able to treat per day, and there are times when these amounts become too high and exceed the plant 's peak flow rate. Cobourg Combats Flooding Ontario Town Upgrading Problem Manholes with Watertight System By Jason Clowater

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