By Carol Martin, Lake Superior Conservancy and Watershed Council
“Pretty much everything we put on our lawns ends up in the St. Mary’s River sooner or later, ” says Don Elliot, City of Sault Ste. Marie, Ontario’s Director of Engineering Services. Dog poop, solid waste, fertilizers, and pesticides from the streets, lawns, and farmers’ fields in the St. Mary’s River and Lake Superior watersheds wash into the river and lake with stormwater runoff, says Elliot. But the city’s sanitary sewer system hasn’t had an overflow since sanitary sewer overflow (SSO) tanks were commissioned, installed in Bellevue Park in 2004.
Overflows have happened in the past during significant hydrological events like heavy rainfall or swift snowmelts, he said. “If you combine stormwater runoff from cross connections with sanitary sewage you can increase your volume by as much as ten times.”
Elliot explained that, since 1968, it’s been illegal to cross connect weeping tiles that drain fields below ground or roof leaders or gutters to sanitary sewer systems in homes in the city, but homes built before then can still have this sort of connection.When there is a storm,water from the roof and yard of that house drains directly into the sanitary sewer system, significantly increasing the volume of water in the system and the subsequent risk of overflow at one or more of the city’s treatment plants.
“If hydrological capacity is reached at any of our treatment plants then we take remedial steps such as eliminating a step or two in the treatment process to speed up the flow, but sometimes overflows cannot be avoided,” said Elliot.
The city has installed meters to warn of impending overflows and in the event of one will communicate a warning to people downstream of the threatened plant. Elliot says statistically an overflow event can be expected about every five years and the Sault would likely overflow in three locations at the same time if the hydrological event were torrential enough to cause overflow.
Downpours in the Sault have been torrential enough for the SSO tanks in Bellevue Park to be used on at least three occasions since they were commissioned, said Elliot. When the volumes at the East End Sewage Treatment Plant got dangerously high, sewage water was diverted to the 12,000 cubic meter tanks to be held for processing. The tanks haven’t yet reached their 4 million gallon capacity, but Elliot says it is likely to happen during a torrential downpour in the spring or fall in the next few years.
Elliot says the City does not treat stormwater runoff and that it is typically not treated anywhere by much more than settling time in catch basins. “After a couple of weeks of hot dry weather, if there is a big enough downpour you can see the solid litter, dog poop and brown dirt flushing straight out into the river.”
While larger bits of solid waste typically settle in catch basins in the city, sometimes a deluge will even break those loose and wash them out to the river, said Elliot. He said that people really need to think about where things go when they wash their cars, change their oil, or flush their radiators in their driveways. “Even in very minute quantities, engine coolant is highly toxic.”
Elliot said the most dangerous wastes are the ones that can’t be seen. “It’s very diluted but there are sufficient amounts of bacteria and phosphates as well as chemicals used in fertilizers and herbicides to be concerned about.”
The stormwater management issues facing Sault Ste. Marie, Ontario are similar for hundreds of communities throughout the Great Lakes Basin: a lack of infrastructure, little to no collection or treatment, and minimal regulations that address stormwater and guide development. Stormwater is truly one of the largest sources of pollution to the Great Lakes. It also provides an opportunity for citizens, organizations, and decision-makers to work together to reduce the pollutants and the volumes of stormwater. The Great Lakes Aquatic Habitat Network and Fund recently produced excellent publications that provide tips on how to get your community engaged in improving its stormwater management. We hope these tools will give you tips about what you can do personally and in your community to address stormwater.
For more information, contact Carol Martin at email@example.com.
For resources on addressing the negative impacts of stormwater, as well as harnessing its many benefits, check out GLAHNF’s latest success stories publication, Let it Rain: From Runoff to Renewal online at http://glhabitat.org/SuccessStories/success.htm