City to tweak lead battle

Hey there, time traveller!
This article was published 18/02/2011 (5530 days ago), so information in it may no longer be current.

The city is searching for a new way to control lead levels in tap water over concerns its current method has increased outputs of phosphorus, which could harm Lake Winnipeg.

Winnipeg has added a form of phosphorus, called orthophosphate, to the water supply since 2000 to control lead levels. About 25,000 city homes are serviced by lead pipes. Orthophosphate forms a protective coating that reduces corrosion that can let lead slip into the water supply.

Kelly Kjartanson, manager of Winnipeg’s environmental standards division, said data show adding phosphorus to control lead has “minimally” increased the city’s output of phosphorus by five or six per cent from the North End water-treatment plant in the last 10 years.

City engineers launched a review of orthophosphate alternatives late last year after Manitoba Water Stewardship raised concerns. Kjartanson said many other cities use orthophosphate to control lead and the search for alternatives has more to do with the optics of adding phosphorus than any actual harm done to rivers and lakes.

Phosphorus is one of the nutrients that contributes to the thick blooms of blue-green algae that have coated the shores of Lake Winnipeg in recent years.

“It’s mainly the optics,” Kjartanson said. “It hasn’t had a major impact on what’s going into the rivers.”

Dwight Williamson, assistant deputy minister of ecological services for Manitoba Water Stewardship, said the Lake Winnipeg Stewardship Board first expressed concern over the city’s practice of adding phosphorus to the water supply in 2006. Williamson said it’s good that the city is reviewing alternatives since there are other options that can lower lead levels in water without adding phosphorus, including forms of sodium and calcium.

“It’s important to keep the lead out of the drinking water, but it’s generally harmful to the environment to add phosphorus to the system,” he said.

Williamson said adding phosphorus to the water system contributes to the harmful algae blooms that have plagued Lake Winnipeg.

Kjartanson said orthophosphate has reduced lead levels in biosolids and is a cost-effective way to protect Winnipeggers from exposure to lead in water, which is harmful even in small amounts.

The city is slowly replacing lead pipes, but the process is slow and costly. Lead pipes are replaced as water mains are renewed, since replacing them all at once would cost $60 million, Kjartanson said.

Most of the lead pipes are in the city’s older areas and homeowners are on the hook to pay to replace pipes on their own property. The city will replace its pipes on the other side of the homeowner’s property line if someone is worried they may be exposed to lead.

The city abandoned its lead-monitoring program in early 2010 when only eight homeowners with lead pipes were submitting monthly water samples for testing. Kjartanson said lead levels occasionally crept above the health guidelines during summer but regulators were not concerned.

The city relies on a system of pipes at its sewage-treatment plant to monitor whether the orthophosphate program is effective. Officials run monthly tests on four different plumbing sets that mimic household water usage to ensure lead levels are below recommended guidelines.

The engineering review on orthophosphate will also examine chlorination alternatives and water stabilization. The report is expected to be finished by the end of 2011.

“We’ve been monitoring our waste-water streams and we’ve found the lead control program has had minimal impact on the effluent going into the rivers,” Kjartanson said.

jen.skerritt@freepress.mb.ca

 

 

What is orthophosphate?

A form of phosphorus the city uses to reduce the likelihood that lead from old pipes can slip into the water supply. Officials add orthophosphate in small amounts in the form of food-grade phosphoric acid, a clear, colourless liquid. It is made up of oxygen, phosphorus and hydrogen, and is found in some food products such as soft drinks.

What is the concern?

That adding phosphorus to the city’s water supply is a bad idea. Phosphorus is one of the nutrients that contributes to the blue-green algae blooms in Lake Winnipeg. City officials say orthophosphate has “minimally” increased their phosphorus output at one water treatment plant by five per cent since 2000.

What is the city doing now?

Looking for an alternative to orthophosphate. A report should be complete by the end of the year.

 

— Source: City of Winnipeg