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By Neco Cockburn, Ottawa Citizen August 29, 2011
OTTAWA — A water main failure that led to a two-month outdoor water-use ban in Barrhaven, Riverside South and Manotick was caused by road salt leaking into concrete and causing corrosion, an investigation has determined.
City legal staff said Friday they do not recommend taking legal action against the water main pipe manufacturer or the installer based on results from the forensic investigation into the Woodroffe Avenue water main failure.
The main failed in January and resulted in an outdoor water-use ban that started in late April.
The investigation concluded that “the failed water main pipe met both the required design standards in effect at the time of its manufacture, as well as those currently in place,” city clerk and solicitor Rick O’Connor wrote in a memo to councillors.
“In view of that conclusion, there is no reasonable prospect of any recovery against the pipe manufacturer,” O’Connor wrote.
The investigation, by Openaka Inc., determined that road salt got into the concrete and resulted in corrosion of the wire and steel supporting structure, O’Connor wrote. Although the 35-year-old water main would normally be protected by a mortar coating, the investigation found that the coating had been damaged at some point, he wrote.
“This damage could have occurred during installation or as a result of later construction work in the vicinity of the pipe,” the memo states.
“It is also possible that the mortar was damaged due to surges/ overloading during operation of the water main.”
Investigators were unable to determine the specific cause of the damage or figure out when it occurred, O’Connor wrote.
O’Connor noted the original construction contract had been destroyed in accordance with the retention policy that had been in effect for the former region of OttawaCarleton.
Although the document may have provided additional background information, “its absence does not affect the legal opinion, in view of the findings contained in the engineering report,” he wrote.
About 80,000 residents were affected by the city’s ban on all outdoor water use, which was initially expected to last until mid-August. After the main’s replacement was finished earlier than expected, the ban was lifted in late June.
Officials have said the new pipe has a special coating to prevent failures, and is equipped with fibre-optic cables that will provide an early warning if it needs repair or is about to break.
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