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Province eyes city's response to lead corrosion problem

Toronto chose a different method for treating lead corrosion

THUNDER BAY — The Ministry of the Environment has no current plan to remove sodium hydroxide from the list of options for corrosion control in drinking water systems.

However, a spokesperson says the ministry is aware of the City of Thunder Bay's recent problem with the chemical, and will continue to closely monitor the situation.

In 2018, with the ministry's approval, the city added sodium hydroxide to the water system to reduce its acidity, thereby lowering the levels of lead in tapwater in older neighbourhoods with lead pipes.

This had the intended outcome, but there was an unforeseen consequence as well – dozens of city households started reporting the sudden appearance of pinhole leaks in copper water pipes.

As a result, the city announced earlier this year it would phase out sodium hydroxide while it studies alternatives.

According to a ministry statement to Tbnewswatch, the chemical is used by many cities in North America including Ottawa, London, Ont., Edmonton, New York City and Boston as part of their measures to minimize corrosion and control lead "without any pinhole issues."

The statement outlined a list of approved methods for municipalities dealing with lead leaching into drinking water because of corrosion:

  • pH adjustments or alkalinity increases to make water less corrosive when it contacts lead bearing-pipes and faucet fixtures. The use of sodium hydroxide is one method of adjusting pH, and the ministry also accepts the use of calcium hydroxide
  • apply a protective coating to surfaces of lead pipes through the use of orthophosphate
  • removal of lead service lines, and lead filters on faucets
  • education and outreach regarding lead exposure and measures residents can take to limit exposure to lead in drinking water

Toronto is among the cities that have opted to use orthphosphate to mitigate lead corrosion.

It started its program in 2014.

Toronto's water treatment and supply director, William Fernandes, told Tbnewswatch orthophosphate was chosen based on "the experience and performance of other systems with similar water quality on the Great Lakes."

Fernandes said tapwater lead levels in homes with lead pipes are now in compliance with provincial regulations.

Tbnewswatch asked the environment ministry how urgent it is for Thunder Bay to come up with a new treatment method.

The spokesperson said "finding an alternative solution in the long-term is important," but added that the provision of faucet filters to 8,700 city households will prevent exposure to lead in the interim.

He said the city has been directed to keep the ministry up to date on its progress.

The city has also been directed to submit a report no later than August 30, 2020 summarizing the measures it has undertaken to that point, the public outreach and reaction, and the results of wate testing including any health-related impacts.

The spokesperson said the ministry will review the effectiveness of the short-term measures and will work with the city to determine next steps in changing its corrosion control plan and implementation timelines.

City officials have said the lead filters that were delivered last month to affected households along with water pitchers are sufficient to last about a year.

Thunder Bay plumbing companies contacted recently by Tbnewswatch reported that they have never received as many calls about pinhole leaks as they have received in recent months.

"We've had more in the last year than we've had in the last 20 years. It's been crazy," a staff member at one company said.



Gary Rinne

About the Author: Gary Rinne

Born and raised in Thunder Bay, Gary started part-time at Tbnewswatch in 2016 after retiring from the CBC
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