Peter Slingsby, one of the industry’s CCTV pioneers, has been involved with Trenchless Technology for more than half a century.

In 1971, he designed and built the first floating camera system for large sewer main inspections in Australia, paving the way for the conditional assessment industry.

Lessons learned in the industry

“Since the first sod of dirt was turned to bury a pipe for drainage purposes, we have looked at better ways of constructing drainage systems, improving efficiency, safety, materials and costs,” Peter said. “Because of the kilometres of pipe of all sizes required to plumb a city, all these factors had to be taken into consideration.”

Peter said the most important thing he has learned from the industry is not to leave rehabilitation too late. “You can go through a pipe and find something wrong. You can monitor it and say ‘okay, let’s monitor and see how it deteriorates’. But really the best thing to do is: if you see something wrong or you see something going wrong, fix it now. Because if you leave it, the more it deteriorates, the harder it is to fix.”

One such example is the recent replacement of the Melbourne Main. The original pipe, which was built in the 1800s, drains practically the entire city. A collapse could flood the Yarra River. “When we first inspected this section of the main around 1974–75, some of these difficulties became very obvious, mainly in keeping the pipe on grade and on track,” Peter said.

Peter said an inspection of the main revealed it may have been in poor condition, but it was still alright. He applauded the authorities for taking the step to rehabilitate the massive main.

“I think Melbourne Water were very brave to do it. They got a tunnelling machine and put a new pipe there. And that would have been done under enormously difficult conditions with that soft silt and sand and decanter under that Docklands area.”

On condition assessment

Inspecting the inside of sewer and water mains has vastly improved the underground infrastructure industry, according to Peter.

“What we’ve realised by doing these inspections is a lot of the problems in pipe were actually created at construction,” he said. “But now, by running a camera through and doing an inspection immediately after a pipe has been constructed, you can tell if it’s been done properly. ”

It was one thing to bring CCTV into sewers, but another thing to make sure that defects captured on film or video were correctly identified. Peter said everyone had different interpretations on what they should score, and reporting was done by handwritten reports.

In 1984–85, with the help of a Board of Works engineer Max Anderson, pipe defects were given a code name and a score with a computer program Peter designed with computer technician Daryl Kingham. The computer calculated a score that highlighted the critical assets requiring rehabilitation.

“An engineer will look at the numbers and think, okay, we have to do this pipe,” said Peter.

Peter was part of the committee for the establishment of an Australian Standard for codes by helping set up the current Australian Standard Conduit and Condition Code, WSA05-2008 Conduit Condition Codes, to ensure consistency and accuracy in coding defects. “Now we’ve got an industry standard to work to,” Peter said. “It means that everybody is consistent in the coding of conduit defects.”

Trenchless discoveries

According to Peter, in the years to come, the trenchless industry can only improve. Like all industries, Peter said there has been challenges along the way. In particular, he recalled the act of cutting holes in liners for branch connections.

“Instead of making a proper repair at the property connection, a rotary cutter was driven up the pipe and a hole cut into the wall of the liner,” he explained. “As an inspection camera operator, it always amazed me to drive up a lined pipe and look at the holes cut into the liner at connections and see the infiltration at these points. It has taken quite some time to come up with answers to this problem and with the introduction of lateral liners and a top hat-type liner that seals the gap between the liner and lateral, the efficiency and life expectancy of a lined pipe can be increased significantly.”

But importantly, the industry has progressed. “Inspection cameras have come a long way in the last 50 years, from my old box brownie mounted on skids, to a high speed camera taking shots every 50 mm or fish-eye CCTV taking a picture of every mm of a pipe.”

Peter is amazed by tunnelling machines.

“For the best technological advance I’d give my vote to the Tunnel Boring Machine that can bore massive tunnels through almost anything with pinpoint accuracy.”

Future of trenchless

“I think the ideas that came out 20 years ago are still here now, but they’ve been refined and they’ve been improved. One particular improvement is the use of different materials for rehabilitation.”

“I think there’s a huge future for the trenchless sector because when you look at the pipe that’s actually been inspected and repaired, it’s a fraction of what’s in the ground,” Peter said.

“There’s a lot of bad pipe underground, so the Trenchless Technology industry will have a lot of work to do in the future. But it can only get better because the ideas and technologies will continue to improve every year.”