Looking towards the outfall in the Wilson Heights Storm Trunk, beneath the slopes of Earl Bales Park

Depths of Salvation

Wilson Heights Storm Trunk Sewer

Dehavilland Creek watershed
Allan Road north drainage
West Don River tributary

Construction Details:
Bored tunnel lined with concrete panels (2800mm and smaller), external concrete spillway delivers outflow into the West Don Valley.

The Wilson Heights Storm Trunk Sewer and its sewershed stretches from the W. R. Allen Road (formerly the Spadina Expressway) and the Downsview Airport lands east to the West Don River at Earl Bales Park. Built in the early 1960s by the Corporation for Metropolitan Toronto, the trunk sewer had two main purposes: first, to provide drainage for the northern part of Spadina Expressway (roughly that part north of the 401); and second, to collect storm runoff from the neighbourhoods of Clayton Park / Wilson Heights that were in the process of  being developed on former De Havilland Airport and Toronto Flying Club lands with suburban single-family and semi-detached housing.

Burying the upstream watershed of De Havilland Creek, the trunk sewer also allowed the part of the creek closer to Bathurst to be infilled, as housing had already been built up around this section in the 1950s. The Dublin Heights Elementary and Middle School and the St. Robert Catholic Elementary School were built over the former creek bed in the late 1960s.

The storm trunk sewer is a deep, bored tunnel located at least fifteen or twenty meters below street level, deep enough to allow it to pass underneath the Wallenberg ravine in Earl Bales Park. This means that tributary, streetside storm sewers must drop a considerable distance to enter the main conduit, requiring multi-level stepped concrete drop structures positions in slots off the main pipe. Several are pictured in the photographs below.

After passing beneath the Wallenberg ravine, the trunk sewer outfalls into the Don Valley partway up the eastern side of a raised finger of woodland that extends southeast from Bathurst Street. A long flume carries the stormwater down to a plunge pool and a short stretch of surface waterway that joins with the West Don. In summer 2010, this outfall is being reengineered with the installation of a stormwater management pond and the diversion of the small pipes that feed the nearby Wallenberg and Timberlane storm outfalls into the trunk sewer.

Because of the visibility of its outfall, the Wilson Heights storm trunk sewer has a history of visitation by area residents much more intensive than most Toronto storm sewers. Graffiti inside the drain ranges from the lewd and absurd to an incredible record of New Year's Eve visits (conceivably by a single group of friends) stretching almost twenty years, from the late 1960s into the 1980s. Most visitors appear to have stuck close to the outfall though, and markings dwindle as you head upstream.

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Michael Cook is available to speak to your organization about infrastructure history, lost creeks, current conditions, and opportunities for change in our management of and communication about urban watersheds, and to work with teams proposing or implementing such change. Get in touch.