Case study: Echo Barrier noise control panels
The Echo Barrier noise control panels being used by Australian contractor UEA on a Tasman Global Access (TGA) project linking New Zealand to Australia’s internet infrastructure have a dual purpose — firstly to absorb sound, and secondly to send a signal to the community that their needs and comfort are being addressed from the get-go.
"An important part of sound control is that it looks good," UEA senior project manager Thomas Carolan says.
"It provides reassurance to the residents. We committed that we’re not going to mess with people’s lives, and we do the best we possibly can."
The TGA project is a joint effort by several telecommunications companies to improve New Zealand's internet connectivity by linking the country with international networks already servicing Australia.
The job requires a big cable that will run from Raglan, on New Zealand's North Island, across the Tasman Sea and into an underground conduit drilled by UEA. The other end of the conduit is at Wetherill Street in suburban Narrabeen, on Sydney's Northern Beaches.
It’s in this quiet street that the Echo Barriers were deployed.
During the course of the project, UEA used a Vermeer D300 horizontal directional drill rig to complete an 800m ocean outfall bore installing a 5-1/2 FH drill pipe. This was left in situ as the telecom company’s required conduit.
Divers then removed UEA’s tooling equipment from the ocean and installed a termination piece on the end of the drill string.
The company then needed to construct a reinforced concrete pit in Wetherill Street to act as the access chamber to pull the TGA cable into at a later date.
To do this, a drill site needed to be set up adjacent to homes and apartments.
Due to the sandy ground conditions, it was initially thought the drilling would have to be in operation 24 hours a day to maintain steering, although once drilling commenced it was found it could be done in 14-hour shifts over six days with no night works.
Regardless, the team recognised that managing the community's expectations would be a critical factor in successful project execution, Thomas says.
"We’re hands on with people," he says. "We spoke to hundreds of people around the area to make sure they knew what was going on."
Because noise is frequently a sticking point in community-project relations, UEA asked Echo Barrier to assess the site and create a design for noise control.
A scaffold system 4m high and enclosing the entire site was erected and a sound attenuation system was installed over the scaffolding to provide noise reduction of up to 50 percent. The 4m height was necessary to mitigate noise for residents higher up.
The final design also included a special canopy and roof for the particularly noisy drill mud recycling unit.
The lightweight panels were affixed to the scaffolding with cable ties, making them easy to put up and pull down, and the wall of noise barriers took shape around the site in about 48 hours.
"People want to know how the project will address their concerns, and having a noise solution design, some case studies, and a responsive attitude provides residents with comfort," Echo Barrier director Ray Lee says.
Echo Barrier makes patented temporary noise attenuation panels that use a special acoustic infill which absorbs sound rather than reflecting it, the company says, reducing noise by up to 32 dB.
The technology has been used on both major and minor commercial and infrastructure projects worldwide, including the redevelopment of the World Trade Centre site in New York.
Once the Narrabeen project was underway, an independent sound test showed an average noise reduction of 18 dB.
Resident James Ritchie says noise levels had been a major concern before the start of the project, but they ended up with just a steady hum in the background.
Thomas’s favourite story concerns one resident who came out and asked when the job was going to start.
"I told him we’re 25m into it," Thomas says. "He said, 'Is that as noisy as it gets? We’ve heard nothing!' "
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