Thursday, November 06, 2014

Inverness Force Main Bridge

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The next Columbia Slough bridge on our mini-tour is the newest, other than the rebuilt Vancouver Ave. bridge. The Peninsula Crossing Trail continues north after the Portsmouth Cut area, and crosses the Columbia Slough on a new-ish bike/pedestrian bridge, just east of the city's ginormous Columbia Wastewater Treatment Plant. Several sources (including the Google map above) insist the bridge and the bit of trail south of it are part of the Columbia Slough Trail, which intersects the Peninsula Crossing Trail just north of the bridge. The Intertwine trail map says it is, a Metro map about the ongoing Columbia Slough Trail project says it isn't. The slough trail is an east-west trail along the north bank of the slough, running a few miles through N/NE Portland, while the crossing trail is a roughly north-south route that vaguely parallels the BNSF railroad across the N. Portland peninsula. The bridge is clearly part of the latter route, not that that's going to stop anyone from making new wrong maps in the future. The map error is out there now, and map errors tend to be strongly self-propagating once they're out in the wild.

Anyway, when I walked across the bridge, I thought it seemed a lot more solid and heavy duty than was strictly needed for a bike and pedestrian bridge. I assumed that was so the occasional maintenance or emergency vehicle could use it too. Then I bumped into an old planning document from 1996 that explained the bridge's hidden secret. It turns out that in the early 90s the city's Bureau of Environmental Services wanted to build a bridge over the slough for the Inverness Force Main, a shiny new sewer pipeline (though maybe "shiny" is the wrong word here), and they figured they might as well put a bike/pedestrian walkway on top, concealing the pipe while they were at it. (Though it seems like they continued calling it the Inverness Force Main bridge instead of naming it after either of the trails.) It's not just any old sewer pipe, either, but a 30 inch main carrying pressurized raw sewage. As you might imagine, it was kind of a bad deal when the pipe under bridge sprang a leak back in February 2014. The public was advised to avoid contact with the slough, which generally speaking is what people do anyway.

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