By Dennis Hanagan –
Citizens and consultants continue to battle the problem of raw sewage flowing straight from residential and business toilets into storm sewers that then flow into the Don River and Lake Ontario.
It’s a problem called combined sewer overflow (CSO), and it happens when a heavy rainfall pours down sewer grates, raises the level of lesser-contaminated rainwater in the storm sewer, and causes the rainwater to overflow and mix with human waste in the sanitary sewer.
The end result is sewage doesn’t get a chance to get to a treatment plant; it pours untreated into the Don and Lake Ontario through sewers meant to handle only rainwater.
MMM Group consultants handed out an 85-page report of graphs, charts and maps to about 40 citizens at Metro Hall May 31 explaining methods including tunnels, shafts, underground storage tanks and chemicals that could be used to remove the black eye Toronto received in 1987 for its dirty harbour water.
That’s when it was cited by the International Joint Commission (IJC) as one of 43 “areas of concern” in the Great Lakes basin because of its poor waterfront water quality.
Says a consultant’s report, “a major cause (of the poor water quality) is polluted water resulting from overflow from combined sewer outfalls into our waterways.”
In response to the IJC the city launched the Don River and Central Waterfront project in early 2008 aimed at cleaning up the Don and the harbour.
Its goals include eliminating “dangerous and unsightly” sewage and reducing “harmful bacteria, pathogens, heavy metals, oils and pesticides” that flow into streams and rivers—and eventually into Lake Ontario, Toronto’s drinking water.
A huge chunk of central Toronto has been cited as the study area for the Don/waterfront cleanup project. It extends from Steeles Ave. to Toronto Island, and from roughly Dufferin St. to Victoria Park Ave.
“The city is experiencing strong development pressure in the study area and must act to ensure that storm water management is not overlooked as development proceeds, or the problem will only get worse,” the consultant’s report states.
But at the meeting, residents questioned why solutions so far centre on cleaning storm water once it is contaminated with untreated sewage. A few suggested building a sewer system in which sewage and storm water would be carried in separate sewers so there is no chance of the two mixing.
Lino Grima of the Centre for Environment at the University of Toronto makes a case in an email for a more “green” approach by “disconnecting road sewers which collect storm water… and sanitary pipes.”
Storm water from road sewers would be treated he says “at new, above-ground, green treatment facilities along the lakeshore and ravines.
Storm water will be treated and released into Lake Ontario at green, attractive, facilities that typically cost 10 per cent of tunnels and tanks.”
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Grima adds the road sewer separation option keeps rain out of the sanitary drain for the foreseeable future whereas the tunnels and tanks project “perpetuates the combined sewers and occasional overflows.”
The Metro Hall meeting heard that Toronto’s development intensity precludes having open-air treatment, and that’s why underground tunnels and storage tanks are necessary.
But Michael Brothers of the Toronto Chapter of the Council of Canadians (TCoC) argues in a prepared statement that “with some imagination” Toronto’s network of ravines with their rivers and wetlands “can be used to clean road runoff before putting it in the lake.”
He says the current plan being proposed “does little to address the storm water treatment issue.”
He says newer communities around Toronto have developed ways of holding rainwater in ponds and wetlands to help curtail the effects of contaminants like oils ands gases that accumulate on roads and get washed down sewer grates during rainfalls.
Brothers says the need to improve the operation and reliability of Toronto’s present sewer system “is obvious.”
But he adds “what is being planned is like putting a catalytic converter exhaust system on a 1950s car. It will work for a while… but it misses the fundamental point that Toronto needs to move to a new sustainable form of infrastructure.”