Melbourne Water Sends Drones into Sewage

Melbourne Water is hoping to fly more drones around its sewage infrastructure to measure gas concentrations, take sludge samples and monitor the dynamic stresses on plastic covers over the lagoons at its Western Treatment Plant

The Victorian government-owned water authority has already conducted two trials of civil infrastructure inspections using unmanned aerial vehicles (UAVs) and is hoping to set up a supplier panel of companies it can contract in for various drone missions.

"To inform that process I'm actually finishing off a paper now thats trying to quantify how much of that need we actually have so we can go out to the market and say we have a certain amount of business [to offer]," Melbourne Water's technology improvement specialist Frank Courtney told the recent Connect 2015 conference.

The utility's first UAV trial saw it inspect the 350 metre spillway for Thomson Dam - Melbourne's main water supply.

"From a safety perspective this is effectively a vertical asset," Courtney said. A usual inspection requires two people to abseil down the face while attempting to locate "anomalies in the concrete structure" and write them down.

"It's a really inefficient, really dangerous process," Courtney said. "It's very costly and very high risk".

The utility brought in a UAV contractor who flew an Ascending Technologies Falcon 8 over the spillway for 20 minutes. Melbourne Water's asset managers had high-quality images downloaded from the flight within an hour.

"We took a process that would normally take five or six people over three days, and we took it down to two people in 20 minutes," Courtney said.

That success saw UAVs engaged in a second trial - a flyover of the Southern Carrier, a 4km long open channel that takes sewage from the Western Trunk Sewer to the Western Treatment Plant at Werribee.

Again, the UAVs were put to work taking high-quality photos and video, however the brief was slightly different.

"The asset manager who was after this particular inspection said, 'I've got a certain amount of money to spend each year. I want to know are there any hotspots along this length of carrier that I can target my spend'," Courtney said.

"He wasn't particularly interested in one little crack here or there, but if there was a hotspot of two or three or four issues in one area, that's where he was going to target his [maintenance] spend."

Courtney noted the Southern Carrier was an old but critical asset.

"We can't turn these things off if we have an issue," he said.

"Regular inspections are absolutely critical because we are very limited in how much or how many of our assets we can actually isolate."

The UAV contractors ran two passes of the carrier using different drones. The first pass, using a Microdrones md4-1000, pointed a camera "straight down" and took photos along the length of the channel. The 28-minute flight was performed autonomously, although engineers and the pilot maintained line of sight by following the UAV in vehicles.

"The accuracy of GPS on the Microdrone was such that we were able to use that vertical height along with the focal length of the camera and the size of the sensor to actually calculate the effective distance of each pixel," Courtney said. "We were able to use that data to measure [the size of] what we found [in the images]."

A second flight followed using a Falcon 8, which captured high-definition video. "That gave us a really good picture of any lateral movement, any vertical movement and anomalies," Courtney said.

Source: ITNews

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Taxonomy

• Sludge Separation
• Sewage
• Water Utility