Brandon's drinking water continues to test too high for THMs. (POSTMEDIA NEWS ARCHIVE)
It could cost millions to get Brandon’s water supply up to provincial standards.
A report set to be received by city council tonight shows Brandon’s tap water fails to meet the acceptable amount of Trihalomethanes (THMs) — a number Brandon has struggled with since a benchmark was introduced in 2008.
The city’s water met all other test requirements by the province’s Office of Drinking Water audit, including E. coli and residual chlorine.
THMs are relatively common in cities where the water supply comes from surface water, such as the Assiniboine River. Chlorine, which is used as one step to disinfect the water, reacts to organic matter — such as decaying plants and algae — in the water source which forms THMs and ends up in the distribution system.
In 2007, the city contracted a disinfection specialist to evaluate the existing treatment, testing and disinfection practices in an attempt to reduce THMs. The specialist revealed that the current treatment process was being operated properly, but that the plant did not remove organics to the levels that were necessary to reduce THMs below the provincial standards.
While steps have been taken over the last several years to reduce the amount of organics coming into the water supply before goes through treatment, THM levels remain higher than the 0.10 milligrams per litre maximum set by the province.
THM levels found in Brandon’s water sources tested four times this year ranged from .047-.161 milligrams per litre.
According to Patrick Pulak, the city’s director of engineering and water services, there are a few options to address the issue, but engineers are investigating the idea of an alternate source of water — ground water — to blend with the river water. The city already blends water sources, but Pulak said they are investigating adding more ground water.
The city can’t rely wholly on groundwater, as the capacity isn’t available. Current groundwater wells are used as an alternative to river water in the springtime flood season when organic levels are at their highest.
Finding an appropriate groundwater source and tapping into it would be "double-digit millions of dollars" to undertake, Pulak said, but adds it’s the best option in his opinion.
"Blending in my mind is the cheapest option," he said.
It’s likely to be a long time before a major project gets underway, and Pulak said it’s possible the city will apply for federal infrastructure funding to for upgrades to the water system needed to bring the city’s water into compliance.
"There are treatment regimes for the removal of THMs. We’re also looking at that," he said.
It is understood, compliance will likely require a major upgrade to the water treatment facility, which will be detailed in the utilities master plan, expected to be introduced sometime this year.
"There are short-term upgrades that are in our budget this year," Pulak added.
According to joint document between the Manitoba Health and Conservation and Water Stewardship, there is not enough evidence to indicate that THMs cause cancer in people, but cancers have been detected in some studies in which mice and rats were exposed to high doses.
As a precautionary measure, drinking water guidelines are set to ensure a low level of potential health risk over a typical lifetime of exposure — about 70 years. Short-term use of drinking water that exceeds the guidelines is unlikely to have an impact on human health, according to the provincial government.
In the report to be given to council tonight, the high THM levels are not a result of the city’s actions, but of the river water’s "quality degradation," and the city is to treat the water with its current processes.
Republished from the Brandon Sun print edition February 18, 2014