Saturday, May 01, 2010

Earl Bales Stormwater Pond

Site of stormwater pond (click to enlarge)

Schematic of proposed pond in the valley. The light green area at the top right is the golf course.

A couple of schematic drawings of the pond. A path on a causeway will lead to a lookout and interpretive area.

This summer a major construction project will take place on the West Don at the southeast corner of Earl Bales Park. This project which is the culmination of several years of planning will create a stormwater management pond that will capture storm water before it enters the Don River. The pond location is at the base of two creeks, Earl Bales Creek and Dehavilland Creek. Both creeks used to run west towards the Downsview Park area but are now mostly buried in storm sewers. The remnants of their ravines are now confined to the park east of Bathurst Ave. Both of these ravines are severely degraded due to flash flooding from storm water.

Outfall from former DeHavilland Creek. This will be diverted into the new pond

The purpose of the pond is to capture the stormwater before it enters the river. Stormwater and its resultant pollution is the single most important environmental problem affecting the Don River today. When rain falls on a watershed, the water is either absorbed by trees and other vegetation or percolates into the ground. The water eventually enters the river at a steady rate. However, in an urban watershed like the Don, ground cover is dominated by roads and buildings. Water falling on these areas is quickly diverted into storm sewers where it floods into the river. These flash flood events tend to scour out the creeks and rivers. The water picks up dirt and mud and other things. All the suspended material including whatever pollutants from the roads (road salt, oil, grease, etc.) is washed into the river which severely degrades available habitat for fish and other water dwelling organisms. The Don River used to be a healthy river teeming with fish but not any longer. The "Muddy Don" got its nickname because we made it that way.

This stormwater pond is just one small aspect of the slow process of river restoration. Its main purpose will be to stop the stormwater from quickly entering the river. The water will be stored here until the suspended material has had a chance to settle to the bottom of the pond. It is estimated that 20% of the 35,000 cubic metres of silt annually dredged from the mouth of the Don River comes from the Earl Bales park area.

The pond site looking southwest toward the foot of Westgate Blvd.

Looking northeast

The pond will also act as a reservoir for two nearby water uses. The Don Valley Golf Course currently draws water from the river for its grass watering needs. The Earl Bales Ski Hill also does the same for snow making during the winter. After the pond is built the water will be taken from the pond instead.

The pond will provide limited habitat for some wildlife. However it will not be a fully functioning wetland since it will need to be periodically dredged which will cause major disturbances in the pond. Yet overall, the effect will be an improvement in the overall health of the river and the Don Valley. I hope to visit the site a couple of times this year to document progress on this project.

Notice of construction at entrance to the valley at Westgate Blvd.


Boris T said...

Hmm interesting, looking forward to check it out. Will there be paths going around it once it's completed.

Chris said...

I saw your post the other night and I went for a visit today hoping to see some of the construction (my son loves "diggers").

They haven't started yet, but I chatted with a fellow "just back from a project meeting" (forestry contractor) and he said they've finally hired the contractors and they will start excavating after July 1.

I also found this page on the city's site:

which gives some details as well (you can dig around for the original planning meetings from 2004 which include lots of details as well).

Found another site of interest which listed the project's budget @ $10,000,000.

I took some new photos as well, but they are just the same as yours but with a lot more growth from the vegetation.

Oh, and I found it interesting that the guy told me that where we were standing, the water would be 10feet over our heads. So it seems like they won't be excavating much but rather building it up. He said the current runoff area would be come a tunnel under the pond to manage extreme overflow.

I queried about the dredging. He said it'd be every 15-20 years the whole thing would be cleaned out and there would be a special area near the front which they'd do ever other year.

Thanks for piquing my interest in the project!