District tripling water main replacement budget until 2021
The municipality will be replacing about 10 kilometres of "very poor" condition water mains over the next nine years at an estimated cost of $1 million per year.
The lines in question are made of asbestos cement (AC) and were installed between 1951 and 1983 throughout the district. Pipes which have lost more than 45 per cent of their wall thickness are considered to be very poor.
Work will begin in about a month in the Hatzic area where the AC mains have lost more than 67 per cent of wall thickness. The old lines will be replaced with pipes made of either ductile iron (DI) or polyvinyl chloride (PVC), which should last 75-100 years, said Rick Bomhof, Mission's director of engineering and public works.
The work could be completed in a month, and there will be minimum impact to residents in the area, according to Bomhof. The new pipes will be laid beside the existing ones and water flow will be disrupted when the new connection is made. Notices will be sent out when service will be interrupted.
Half of the work will be done by the district and the other half will be contracted out to determine the most efficient and cost-effective method.
AC mains are a safe way to transport water and not a threat to public health in normal use, however, it can be hazardous when the asbestos fibres are airborne, explained Bomhof.
"The use of AC pipes has been discontinued in North America in the early 1980s mainly because they are difficult to repair and may cause potential health concerns on worker safety," states a report to council.
AC pipes are also vulnerable to leaks, explained Bomhof. They can be brittle and if it's not properly imbedded in sand, any vibration can cause cracks or breaks. Bomhof noted there have been breaks along the Lougheed close by the train tracks.
Last year the district had about 23.5 km of older AC water mains surveyed for leaks and structural integrity. About 45 per cent of those tested were in very poor condition, and another 38 per cent (8.2 km) were in "poor condition," meaning 30 to 45 per cent of the wall thickness had been compromised. The rest of the pipes have minor or moderate degradation.
The poor condition pipes will be replaced after the worse ones have been upgraded, said Bomhof.
The district owns about 174 kilometres of water mains, most of which is DI (121 km). About 44 km are AC pipes.
The condition of the AC pipes was tested with sensors using acoustic-based technology, which measures the time it takes the signal to travel from one end to the other.
Funding for the project will come from the water capital reserve, and council has agreed to increase that fund from $300,000 to $1 million annually until 2021.