The last of the large waterfalls on the way up the Spadina Storm Trunk.

Spadina Storm Trunk Sewer

Water/Sewershed:
Castle Frank Brook watershed
Lower Don River tributary

Construction Details:
Large diameter, concrete panel lining. To deal with the above ground topology, the main conduit contains a long series of drop chambers and plunge/settling pools.

Also Known As:
Park Drive Drain

Further Reading:
lostrivers.ca
infiltration.org
8 Southern Ontario creeks we could start daylighting tomorrow

The Corporation of Metropolitan Toronto's dream to drive the Spadina Expressway into the heart of lower Toronto died in 1971 at Eglinton Avenue, when then-Premier Bill Davis announced that his government would not support extending the highway. The decision was a victory for a coalition of citizens' groups that had opposed the expressway since it had first been announced more than ten years earlier. For more than a decade, ratepayers associations, academics and residents of the City of Toronto and Borough of York had fought Metro's highway plans in the halls of local government, at the Ontario Municipal Board, in the media, and in direct appeals to the provincial government. The decision to cancel the expressway saved neighbourhoods that today are among the best-loved in Toronto, including the Annex, Chinatown and Kensington Market, along with the lower profile mid-town neighbourhoods around the Cedarvale and Nordheimer Ravines, and is a victory that is still remembered and resonates today.

What generally isn't reflected upon are the substantial changes that were perpetrated between Eglinton and Davenport by the expressway project despite the fact that its road bed was stopped at Eglinton. Hundreds of houses were expropriated to make way for the highway, its access ramps and other infrastructure; many were demolished by intention or neglect, while those properties that hadn't by the 1990s been turned to parkland or other uses by Metro or the City of Toronto were sold for many times their original values. This expropriation program changed the character of the neighbourhoods it touched, removing houses, leaving others vacant for decades, and expelling long-time residents. However, the greatest changes were reserved for the Cedarvale ravine itself.

To the extent that the expressway's designers at Metro had sought to limit its impact on surrounding neighbourhoods, the 'mostly empty' Cedarvale ravine had seemed the perfect route. In addition to vehement opposition from residents and politicians in the Borough of York, where the ravine was one of the only substantial pockets of park land, there was the small matter of the Castle Frank Brook and its Cedarvale Stream tributary, a creek system that had already been buried east of Avenue Road but still flowed on the surface through the ravine. Sometime in the 1960s, this creek system was buried in the Spadina Storm Trunk Sewer, the largest of Metro's expressway-related storm sewer projects (see also: Wilson Heights Storm Trunk Sewer, North York Storm Trunk Sewer).

Six kilometers long, the Spadina Storm Trunk Sewer is one of the largest, longest and most heavily designed storm sewers in Toronto, routing the middle part of the Castle Frank Brook watershed not only underground but out of its own basin and east to the Yellow Creek. To deal with the substantial change in surface topology experienced on its way down the Cedarvale/Nordheimer ravine system, the Iroquois shoreline and the Yellow Creek ravine, the trunk sewer was designed with an extensive series of waterfall chambers, including four large split structures where the flow of the drain is divided into two side-by-side drops of about fifteen feet. Each fall includes a rounded top weir, long plunge pool, churn blocks and access catwalks reached by ladder; the four largest falls are serviced by two levels of catwalks. The design of these plunge chambers appears to be fairly unique, as I've yet to encounter it anywhere else.

The main conduit is a round pipe 3.75 meters in diameter, except in one section beneath the Nordheimer ravine where the tunnel's height extends to 4.2 meters. The walls are built from precast concrete panels. Access manholes are mostly found at the plunge structures, and many of the lids have been secured from above with steel washers. The main trunk sewer begins roughly at the top end of the Cedarvale ravine, where two smaller RCPs join; these RCPs provide storm drainage for the neighbourhoods around Eglinton Avenue at the Allen, and appear to contain a combined sewer overflow or other source of sanitary sewage. At the other end, the sewer outfalls into the Park Drive Reservation east of Mt. Pleasant Avenue, where it now feeds a remnant of the Yellow Creek as it flows southeast to the Don River.

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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.