April 21, 2008

Port Moody’s first rechlorination station uses regular table salt instead of concentrated chlorine or chlorine gas.

Table salt feeds Port Moody’s new rechlorination station

Jean Sorensen

correspondent

The City of Port Moody has joined a growing number of municipalities that are opting for the low-risk On-Site Electrolytic Chlorination System (OSEC).

It produces .8 per cent sodium hypochlorite solution from food-grade salt and is the city’s first re-chlorination station.

Port Moody’s IOCO road rechlorination facility was designed by Dayton & Knight Ltd. Consulting Engineers of North Vancouver and constructed by Westport Construction Group Inc.

Mark Webber, Westport’s president, said his company and sub-trades, have completed most of these stations in British Columbia and are currently bidding on another on Vancouver Island.

The Wallace & Tiernan (Siemens) technology is finding appeal because it reduces the need to transport and handle concentrated chlorine solutions or chlorine gas.

The OSEC system produces the weak chlorine solution on site according to the water system requirements, reducing the potential for chlorine degradation.

“It’s a slick system,” Webber said.

“Once it’s hooked up and running – you can see it bubble and boil – it’s pretty well trouble-free.”

The city receives water from Metro Vancouver, the former Greater Vancouver Regional District.

During transport through the distribution system to the city, the chlorine residual is reduced by the long contact time within the pipe.

A minimum level of chlorine residual must be retained in the water to meet current Canadian health guidelines for drinking water.

“We had some low residuals of the chlorine at the extremities of the system. These were identified by health authorities and they had raised concerns about the residual level,” said Brian Carter, Port Moody’s operations manager.

An analysis of the water identified the need for some form of treatment or re-chlorination station.

Further cost analysis found that a re-chlorination station on IOCO road would best serve as a solution.

The site chosen was in front of an environmental sensitive area and fish hatchery.

It raised concerns with environmental groups.

Jacques Whitford environmental consultants were called in to provide an assessment and set out recommendations to mitigate the impact of a spill.

For example, said Carter, the weak chlorine solution is contained in a double-walled tank, the building’s footing was raised over the slab so that it would contain any spill from a pipe break, and the building is equipped with a drainage system that collects and diverts any spill to the sanitary sewer system. Further alarms were placed on site and a sulfate-neutralizing agent was kept on hand. Construction on the $385,000 re-chlorination station started in September 2007 and finished in early March 2008.

Environmental concerns were incorporated into the construction.

The station has been insulated to reduce heat loss and has a temperature-controlled heating system and a fan that can keep the building at pre-determined temperatures, eliminating the need to constantly run them.

“The building is also built in a shady area so that the fans run less often in the summer time,” she said.

A reduced need to truck materials to the site also reduces the environmental footprint.

There are an estimated 70 on-site chlorine generation systems now in use in B.C.

Their popularity is based upon the fact they use a benign substance, table salt,

“(They) are really fail-proof, reliable, and safe with all the controls and alarms built into the system,” Chiu said.

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