Wawa Municipal Council reviewed efforts to address a years-long water advisory during last night's Corporate Planning meeting.
A presentation by Kresin Engineering outlined the process since Algoma Public Health issued the advisory in November 2014, over levels of trihalomethanes (THMs) that exceeded Ontario Drinking Water Quality Standards.
The presentation noted tests were conducted to identify the source of the THMs, which are a result of organic material, dissolved carbon, reacting with chlorine used to treat the water.
Though the tests found "very good quality" water from Wawa Lake, it was noted the raw water had colour, dissolved organic carbon (DOC), and total dissolved solids exceeding standards, while the membrane filters don't remove DOC, though no issues were detected with the filters.
Tests found THMs formed rapidly in the chlorine contact chamber - with the rate of formation slowing after - though Council was told switching to chlorine gas wouldn't give a different result, and - while Councillor Bill Chiasson also noted the biggest issue is in the Michipicoten River Village - he was told that's because there's more time to form THMs.
While rust was detected in the interior of the Mission water tower, it was noted that's since been re-lined - and a mixer was installed to "keep the water fresh" and combat freezing - while changes were recommended to optimize the treatment operations, with a THM study last year finding that an aluminum sulphate coagulant was able to substantially reduce the THM level - and even reduced the amount of aluminum found in the water.
Council was told the operational changes brought THM levels around 80 micrograms per litre - below the 100 microgram limit set by standards, though still high - though using the coagulant would bring that down further.
Kresin recommended an alum dosage of 15 milligrams per litre, but on a seasonal basis - during the warmer months, when THM levels are usually higher - monitoring the results to confirm long-term effectiveness, though it would require a modification of current permits.
No decision was made during the meeting - with questions raised about the costs of the coagulant - though a full staff report and recommendation is expected at a later date.