Virden gets help to fight arsenic in tap water

The Town of Virden is once again doing battle with an invisible enemy… arsenic in the tap water.

In spite of new water treatment procedures implemented last year at the Virden plant, levels of the naturally-occurring poison have exceeded the federal limit of .01 mg/L since late 2018.

The highest it reached was in November when arsenic was two and a half times the limit set by Health Canada.

Test results for 2019 so far:

(Testing by ALS Environmental)

The current situation may seem familiar because about one year ago, the 2017 annual water report revealed arsenic levels higher than the acceptable limit on 10 tests out of 15.

The Provincial Office of Drinking Water investigated and made several recommendations to rid the treated water of enough arsenic to meet the guideline. They included backwashing the filters more often and using a different water treatment chemical.

Those measures were implemented and helped for a while, but by October, 2018 the problem had returned.

GETTING HELP

At the July 9, 2019 town council meeting, councillors agreed to hire the Manitoba Water Services Board (a crown corporation that helps municipalities with their water and sewage works) to assist with the arsenic removal challenge. The Town must pay for this service at a rate that has not been disclosed.

Mayor Murray Wright says the MWSB will train Virden waterworks staff on how to do a more thorough cleaning of the greensand filter system.

A spokesperson from the MWSB explained their theory on what’s going wrong and what needs to be done:

“The Town of Virden adds a polymer to the water prior to the greensand filters for better arsenic removal. However, the polymer is causing plugging of filter media and conventional cleaning mechanisms are not effective enough.

“Manitoba Water Services Board maintenance staff have suggested a more aggressive cleaning method for the town, and will assist them through the implementation process.”

It’s unknown when this process will be started but the Town is taking other steps in the meantime to improve the situation.

They’re replacing a $100,000 membrane in the reverse osmosis system with a finer mesh in hopes it filters out more of the arsenic. A spokesperson says the cost will be covered by the federal gas tax fund rather than local taxpayers.

As well, the search for a new source of groundwater to supply Virden’s needs is under way. The MWSB is in charge of the project and will soon start drilling test holes. It’s unknown how long it might take them to find and connect a new source of water to Virden’s water plant.

Meanwhile, Town Council says the Chief Medical Officer and the Office of Drinking Water are aware of and monitoring Virden’s arsenic levels and have not ordered a drinking water advisory. They remind water customers that the Health Canada limit of 0.01 mg/L arsenic is based on lifetime exposure to the chemical.

BACKGROUND

The Town of Virden has struggled for many years to control arsenic levels in tap water. In 2009, it installed a reverse osmosis system at the water treatment plant which uses high pressure to force water through membranes. For a while, arsenic levels met the standard but then began nudging upwards.

This was to become a common scenario: a new procedure/equipment works for a few months, then loses effectiveness without any clear reason.

Greensand gravity filters were installed in March, 2016 and did the job for a few months but by January 2017, the filters “started to have occasions where we were not in compliance,” said the utility manager’s report at the time.

In spring of 2018, the provincial Office of Drinking Water stepped in to investigate. They recommended more frequent flushing of filters and a new water-treatment chemical which worked for a while, but again high levels of arsenic returned and have remained above the limit since November, 2018.

Related story, May 2018: Arsenic returns to Virden tap water