Among other things, one of my projects in the past month was pulling an old 40m water main out of a culvert under the Trans Canada Highway. We had no information on the condition of the culvert or exactly how the pipe was held together, we spent several utilities meetings working through possible solutions and problem-solving to find a cost-effective method as our first attempt, working up to more complicated removal and replacement options from there in case the easiest option didn’t work.

So how do you remove an asbestos cement watermain in a steel culvert of unknown condition buried over 8m deep in the Trans Canada Highway road right of way?

Carefully! The watermain appeared to be restrained with cable, but we had no idea of how difficult it would be to pull the pipe out, whether it was on skids of some sort, whether the culvert was intact or whether the pipe would get caught up on something. Our solution was to pull the pipe out by threading a cable through the watermain and pulling with a tow truck, preventing the pipe from separating inside the culvert. Using a cam-lock on the cable allowed the crew to quickly disconnect and reconnect the tow truck’s hook to the cable. Watch the video below for a time-lapse of the method ((By the way, my guys work fast, but not that fast, this has been sped up 8x using the iPhone app Hyperlapse!)).

When we had the pipe pulled, we inspected the culvert with a CCTV camera and found one section that will require minor repairs that is near the end and easily excavated. Next step is to install the new PVC watermain in a similar fashion, but with modern restrainer joints between pipe sections, looks like we’ll be doing that next week.

Published by Mike Thomas

Mike Thomas P.Eng. ENV SP, is the author of and Director of Engineering at the City of Revelstoke in the Interior of British Columbia, Canada.

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