Connected Cities, Engineering, Water

Looking at the video footage relayed back from the inspection robot making its way along the storm drain tunnel, it is difficult not to be impressed by the craftsmanship evident in the tunnel’s original construction.

This is a very old tunnel, built more than 150 years ago in Victoria, British Columbia, when brick was the preferred material for the earliest underground sewers.

The tunnel, and others of its kind, was constructed using many non-circular sections, such as egg-shapes, various arches and more. It is this unique architecture, and its longevity, that provides a sense of wonder to those who can see it today.

But the tunnel is not a historic relic, and this is not an archaeological project. It still serves the city and, with some help, it can continue doing so for hundreds of years more.

Victoria’s brick-lined sewers represent approximately 10 kilometres of the city’s overall storm drain infrastructure. In some areas they’re even older than neighbourhoods above them. And while they are in good condition for their age, they do require renovation and maintenance to sustain their structural integrity.

The alternative of digging them up and replacing them with modern sewer-pipes would be considerably more costly than renovation and would have a significant impact on the local neighbourhoods and the people who live and work there.

Our work involves identifying the problem areas with the help of our trusty robot and repairing them with trenchless rehabilitation.

One of the more innovative solutions is cured-in-place pipe (CIPP). CIPP provides a new liner that fits closely to the host pipe, stabilizing it and arresting all of the mechanisms that cause brick-lined sewers to deteriorate, such as leakage and loss of surrounding soil support. Further it provides the necessary structure to support all of the loads formerly carried by the existing sewer. And it can do all this without the need for invasive and costly excavations.

Achieving success in managing aging underground infrastructure comes down to making the right decision at the right time to support the goals of the community. Accurate inspections identify problem areas and give us a better understanding of what solutions work best for the need, and over what timeframe the solutions need to be implemented.

In the process of this work, inevitably we cannot avoid covering up the brick-lined sewers and obscuring our view of them going forward. But we end up achieving the next best thing – extending their role and function for many generations to come. This might be just as impressive to the original bricklayers, if they were here today, as it is for us who marvel at the original craftsmanship.

 

Chris MaceyChris Macey (chris.macey@aecom.com) is AECOM’s technical practice leader for condition assessment and rehabilitation of pipelines in North America.

 

 

Originally published 12.17.2014

Author: Chris Macey