Sunday, June 21, 2015

Smart Centre's 629 Eastern Development - Stormwater Management Opportunities

By Michael Holloway
Ward 30 Bikes
Sunday, June 21, 2015

This is part of a series of articles exploring the lost rivers of east Toronto, and how their still existing flows and stratification under the built form can be harnessed to more cheaply and more sustainably manage increases in the extent and regularity of extreme weather events due to climate change.

I'm reading the updated Functional Servicing & Stage-1 Stormwater Management Report by StudioCentres about their proposed development at 629 Eatsern Ave -

Community Meeting coming up this week:
June 24th,
7pm, at
629 Eastern
Paula Feltcher e-newsletter | StudioCentre development application at 629 Eastern Ave. |

It looks to me like Smart Centre (and perhaps also City Staff) aren't aware that there is a river running under the west side of Winnifred Avenue at Eastern Avenue.

From StudioCentre | Downloads | Functional Servicing & Stage-1 Stormwater Management Report (page 9 of 79):

(my emphasis)
3.2 Stormwater Management

Existing Conditions

There is an existing 1050mm diameter storm subtrunk sewer located within a service easement situated on the western property limits of the subject site that flows southerly from Eastern Avenue to Lake Shore Boulevard East and services the western portion of the existing site (i.e: Revival Site). It is our understanding based on discussions with City of Toronto staff that this existing 1050mm diameter storm sewer typically runs at capacity under minor storm events and is approximately one third full during dry weather conditions. Given that the subject lands are approximately 1.0 – 2.0 metres above the level of the lake, it can be inferred that this storm subtrunk sewer naturally receives backflow from the Lake Ontario. In addition to this 1050mm storm sewer, there is an existing 450mm diameter storm sewer that consists of the minor local system on Eastern Avenue that appears to primarily provide drainage for the roadway.

The always 1/3 full storm sewer on the western extent of the Studio Centre property is not I believe, just 1/3 full under dry conditions due to seepage from high lake front water table - it is very likely that it is 1/3 full all the time because the river that flows in a line from Dundas/Boston down to Eastern/Winnifred is flowing through it!

It is likely that the river has been redirected into sewer pipes as it crosses the Queen Street Trunk sewer and then again at Eastern where it then flows back to Pape and down the 1 metre subtrunk line noted above.

Interestingly - the flow from that 1 metre trunk line then travels down to Lake Shore where it connects to an east-west trunk sewer that then turns south under Carlaw and empties into the Turning Basin. You can see this flow any day of the year; it comes out just under the water surface, at the northwest corner of the Turning Basin, about 50 metres south of the corner of Commissioners and Carlaw.

My line here is about bringing the lost rivers of east Toronto back to the surface as part of a sustainable stormwater management template for the entire South of Eastern and Port Lands area - including this article on the StudioCentres development at Pape - but also with regards to the First Gulf development on the old UniLever lands - under which a river once flowed into the historical Ashbridges Bay at approximately between Saulter St and Bouchette just west of McCleary Park.

If I were designing a large parcel of land like SmartCentres' 629 Eastern site, I would start by understanding the existing and historical conditions of the property - rather than seeing it as a nice square of land that is ideally placed in the geography of the real estate market to make gobs of money after it is developed in some manner defined more by a business model than by the neighbourhood which it is in (which is what this plan appears to be).

As a stormwater management system, revealing the lost rivers of east Toronto is not only a sustainable system (in that global temperature change is causing increasing frequency, and more intense extreme weather events), but is is also a stormwater management system that would:
  • immediately mitigate basement flooding on the lake front lowlands between Dundas and Eastern;
  • add value to the existing neighbourhood properties and the South of Eastern Employment lands;
  • beautify the waterfront neighbourhoods; 
  • remediate brownfields over time;
  • add to the health and well being of the residents in a intensifying context; 
  • create a world tourist destination;
  • act as a transition element between the old neighbourhood and the new in the form of valley-like built lineal Parks north-south.

So instead of development characterized by boring intersections at Pape, Winnifred, Caroline and Larchmount - and a built form defined by the existing glass and sheet metal street wall at the bottom of Winnifred ...

.. the possibility exists to start with a Lower Winnifred as a winding, bioswale edged - wet-weather open water lowland (dry-weather wet detention basin) with a winding woonerf style neighbourhood street that acts to define the character of the development.

Later - as consecutive extreme weather events continue to increase the cost of maintaining and expanding the under-the-street trunk sewer system - the City might decide that running volatile rivers inside confined stormwater truck sewers under streets might be a losing proposition going forward (an opportunity lost in the expensive basement flooding mitigation project now underway) - and begin the process of bringing the lost rivers back to the surface by adding a wet bioswale to Winnifred starting at Queen, and then perhaps extending it into south of Eastern across the Studio Centre property as a river-feed, open water canal (and extending that south across the Port Lands to the Lake as those precincts develop).

Added benefit: mixed sanitary sewer and river flowing storm sewers would be separated - thus freeing up capacity at the Ashbridges Bay Treatment plant which has to treat slightly infiltrated stormwater/sanitary sewer water during wet weather (which is accomplished by simply adding chlorine to the massive flow and flushing it into the Lake).

That's all for today - I'm continuing to read Studio Centre's Functional Servicing & Stage-1 Stormwater Management Report.


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