The outfall of the William B. Rankine hydroelectric tailrace. The glow of the illuminated Horseshoe Falls is visible at far left.

The hydroelectric tailrace of the
William Birch Rankine Generating Station

Niagara Falls, Ontario. Commissioned 1905. Decommissioned 2005.
Michael Cook

Archival Material:

By now, what with the powers of digg and metafilter, if not your own exploring of this very website, you've heard about "the Niagara tailrace tunnel, you know, the one those crazy guys rappelled down into." But, unknown to most of the link-aggregating denizens of the internet, there is in fact a second massive brick hydroelectric tailrace tunnel on the Canadian side at Niagara Falls.

Let me introduce you to the tailrace tunnel of the William B. Rankine Generating Station.

If you've been to Niagara Falls, and particularly if you've viewed the falls from the Maid of the Mist or from the American side, you may have noticed the gaping concrete portal on the side of the gorge just downstream of the Horseshoe Falls, between the external Behind the Falls viewing platform and the powerhouse of the Ontario Generating Station. This is where the tailwaters of the illustrious William B. Rankine Generating Station — the last of the original industrial generators at Niagara Falls to still produce power — entered the river at the end of a 2,200 foot long tunnel.

With the plant decommissioned near the end of 2005, only a small amount of water leaking through the plant's foregates or infiltrating through the walls of its wheelpit now flows through the tailrace. Accessible only by way of a difficult hike over the boulder field or unstable slopes that lie between the river and the sheer cliff of the upper gorge, the tunnel is also defended by the variable river level, which for much of the day, much of the year, submerges the final approach and ledge from which the portal can be accessed. In November 2006, the stars, wind direction, and river level aligned to allow us to enter this magnificent conduit, and through it reach the very belly of the slumbering beast that is the Rankine station.

Thanks to the recently published Canadian Niagara Power Company Story, I can tell you more about the construction and history of this tunnel than just about any other underground structure I've ever been inside. Work began on the tailrace during the summer of 1901, with the excavation completed by December 1902. Preparing and lining the tunnel took another year and a half, with work completed in May 1904.1

Blasted through the bedrock, the tunnel was reinforced with concrete and then lined with a single layer of vitrified brick (a departure from the multiple layers of cheaper brick used in the Toronto Power Company tailrace and the one at the Adams plant across the river). An elongated arch 18.8 feet wide and 25 feet tall, the Rankine tailrace cuts an incredible cross-section in the darkness beneath the Niagara Parkway. Incredibly, the tunnel's brickwork is still largely intact despite a hundred years of tailwater flowing through it at thirty feet per second. The space feels very different than the Toronto Power Company tunnel; here you're basically walking into a cathedral from a point that is technically above ground, and with that comes a change in atmosphere, in perspective, in scale.

After walking the 2,200 feet of tunnel to reach the plant, we found ourselves looking into the very bottom of the Rankine wheelpit. Unlike at the Toronto plant, here there is only a single tailrace, and draft water from the turbines pours straight down onto the floor of the pit, which doubles as the start of the tunnel. Despite the plant's decommissioning, this area is still very wet, with water pouring off the walls, through the trash rack that runs the length of the plant, and from the turbine draft tubes hanging directly above you, suspended in the great brick and metal space that is the innermost sanctum of this temple of hydroelectric power. At the far end is a surge pit designed to absorb sudden increases in load that otherwise might have overwhelmed the capacity of the tailrace tunnel and flooded the plant. Similar pits exist in the draft tunnels of the Toronto Power Co. tailrace

Sitting along the shoreline after dark, so close to the thunder of the Horseshoe Falls, is an experience as magical as exploring the tailrace tunnel itself. Together, they combine to produce an absolutely unparalleled experience of water, of the indestructable impression wrought on the landscape by the ninety-years flow of water of such power and energy that an entirely new version of civilization was built upon its shoulders. Along with the magnificent and largely intact power station at its upstream end, this tunnel is an irreplaceable portal into a key period in our country's history of industrial development, and while I'm not one for architectural sentimentalism, both the tunnel and station should be celebrated and — dare I say it — preserved to be experienced and understood by future generations (not to mention our current one).

  1. 1. Norman Ball. 2005. The Canadian Niagara Power Company Story. Fortis Ontario.
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