Resident upset at street flooding woes

This is what Ellwood Drive West looked like after a June 22 downpour.

"There's nothing like waking up to the sound of waves washing upon a shore - unless that shore is your front yard and you live in Bolton."

That's how Kyle Shilke, a resident on Ellwood Drive West, expressed his consernation at recent flooding in his subdivision.

During the thunder storms in July, Bolton and surrounding area were punished by the brief yet torrential downpour which left sewer systems unable to cope with the amount of water on the street.

Shilke's said his subdivision, like others in Bolton, remains unassumed by the Town after two years, since the last home was built on Ellwood Drive West, completing Pacific Homes's Heritage Hills subdivision.

"Storm after storm my neighbors as well as myself have placed calls into the Town of Caledon, the Region of Peel and of course, Pacific Homes to no avail," he said. Shilke said typical Town responses have been since the road is unassumed, they don't take responsibility for it.

Shilke said cleary the drainage design is flawed.

He stressed every time a major down pour occurs the sewers (which there are only two of in the main area of his street) cannot handle the flow of water. It doesn't matter that torrential downpours are infrequent - he wants answers.

"What I do care about is that in the last flood the waters rose up beyond the boulevard to our front lawns and created a mess of everyone's landscaping. Furthermore, this was a garbage day, so add to the fact that blue and grey bins as well as garbage bags began to float around the neighborhood creating unsanitary and unhealthy conditions."

Shilke said during his cleanup, he noticed the two electrical boxes, one for cable the other for phone, were partially submerged.

He added the trash collector could not pick up the garbage, citing safety reasons. He did return late in the day to pick up the garbage.

"I, like my neighbors pay my taxes like everyone else," he said, asking that the Town give him the answers he needs.

According to Craig Campbell, Caledon's public works and engineering director, roads are quite commonly utilized as the overland flow routes for excessive storm water conveyance. This is the case for Ellwood Drive West, as illustrated by Schilke's situation. The overland flow route carries the waters that exceed the capacities of the storm sewers to storm water management ponds via roads and channels. The overland flow route is designed so that water does not exceed beyond the property limits of the roads' right-of-way.

"Mr Schilke's photos clearly show that the limit of the water is within the Town's right-of-way and the overflow route is working as designed," he said. "Once these extreme storm events stop, the sewers have a chance to play catch-up, and the water completely drains from the road."

The storm sewers at this Bolton location - and in almost all developed areas in Caledon - are designed to handle what is technically known as a "1 in 10-year" storm frequency event. Campbell said this is a typical standard for almost all municipal infrastructure in developed areas. (Some municipalities only have a requirement of a "1 in 5- year" or even a "1 in 2-year" storm frequency.)

A "1 in 10-year" event means the storm sewers are designed to handle a rain intensity of all storms that would historically and statistically happen within a 10- year return frequency. Anything beyond the intensity of a "1 in 10-year" event will cause the storm sewers to surcharge, and excessive storm water must then take an overland flow route.

The overland flow routes are designed so that the water never exceeds a depth of .3 metres (one foot) in the deepest spot (at the gutter of the road); the centre of the road will only be 75 mm (3 inches) deep. This allows the passage of vehicles on the roadway, in particular permitting emergency service access to all areas.

The Town of Caledon does not advise people to enter the water in these conditions, however, the depth of water is relatively shallow and the velocities are very low. Buried hydro systems are designed with these conditions in mind. The water soon dissipates through the storm sewers after the end of the storm.

Campbell admitted that debris and inconvenience can be caused by the overland flow routes, but these are typically short-lived and are relatively minor issues.

"It is not practical nor economically feasible to build underground infrastructure that would carry storm water from '1 in 100- year' events in all areas, as the pipes required to carry that quantity of water are too large and too expensive beyond any reasonable practice," he added.

Campbell said the storms Shilke mentioned resulted in intensities that approached the "1 in 100-year" event. In fact, the 2005 flooding happened during a storm that caused more than $500 million in damage throughout the GTA; the same storm that washed out a massive culvert on Finch Avenue in Toronto.

During both the 2005 event and the recent 2007 event, the overland flow routes in many areas of Caledon conveyed storm water from the intense rainfalls which exceeded the capacity of the storm sewers - and no damages of any significance occurred.

Campbell added experiencing two storms with this intensity within three years is not typical of this area. However, it does not mean it can't happen again. Climate change is surely influencing storm intensities of late. Local conservation authorities warn that storms intensity and frequency of this nature may become more common than history and statistics once suggested.