Beneath Upper Ottawa Street, a grille in the ceiling illuminates a large pool that serves as a gross pollutant trap. The grille provides access should Hamilton Water and Wastewater want to vacuum the solids out of the pool.

Mountain Juggernaut

Stonechurch Storm Trunk Sewer

Upper Ottawa subwatershed
Red Hill Creek watershed

Construction Details:
Very large arched and rectangular concrete conduit, with five-foot-deep central channel and (mostly) dry side 'walkways'. Major sidepipes and most of the smaller, upstream portion west of Upper Wentworth Street are smaller diameter RCPs.

Years after we found it, the Mountain Juggernaut remains the largest known storm sewer in Canada, at its best a massive, arch-ceiling loaf-shaped conduit with a 5' deep channel running down its centre and broad ledges on either side. Remove the ledges, and you could fit a great many things inside it. 

Running for more than 6 km under the southern reaches of development on Hamilton Mountain, the Mountain Juggernaut is an incredible, awe-inspiring construction. Downstream of the main trunk conduit, stormwater flows into a large settling pond that is perhaps 25 metres long, as broad as the drain itself, and at least six feet deep. One can only imagine the nastiness that is likely found at the bottom of this spectacular gross pollutant trap — luckily no one has ever walked into this one by accident.

Other amazing features include gorgeous slot-shaped ceiling grilles crossing the entire width of the drain, a heavy equipment access shaft, ancient calcium straws, and a strange over-under configuration of pipes inside one of the sewers subsidiary arms. Humps of cement built into the ledges make the drain a challenging hike and may serve as surge-control structures, obstacles meant to slow the drain's undoubtedly driving flow during major storms.

Ultimately you reach the top end of the loaf-shaped conduit, where the central channel terminates in a slide. There's an uncomfortable amount of sanitary contamination above this point (low quantities of it are a staple of the drain's entire length), but if you push on you eventually get a slightly interesting waterfall and then diminishing RCP for your trouble. Ultimately the pipe shrinks away to nothing, and you're left to pop out of it through a manhole in someone's front lawn.

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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.