Noise Effectively Controlled During Construction of Scotland’s Biggest Wastewater Tunnel

Project Overview

When completed, the Shieldhall Strategic Tunnel will be the largest wastewater tunnel ever built in Scotland. It runs for 3.1 miles under the south of Glasgow and is part of the most wide-ranging upgrade of the city’s wastewater network since Victorian times. Big enough to accommodate a double-decker bus, the tunnel will improve water quality in the Clyde and help to reduce flooding.

For this mammoth undertaking, Scottish Water appointed contractor CVJV, a joint venture between Costain and Vinci Construction Grands Projects. Work started in October 2014 and is due to complete early in 2018.

After preparing the ground – which included installing 675 piles – the work of digging the tunnel itself began in July 2016. Since then, a state-of-the-art, 1000-tonne, 150-metre-long tunnel boring machine (TBM) has been cutting through rock at a rate of about two millimetres per minute, and should complete tunnelling later this year.

The tunnel route was carefully selected to minimise disruption. Even so, much of the construction took place within and close to residential areas, so containing the works-noise represented a significant challenge.

Challenge

Although the route of the tunnel was carefully planned to minimise disruption, it still ran close to several residential areas. It was therefore essential to adopt measures that would keep noise levels within acceptable limits.

The tunnel route was carefully selected to minimise disruption. Even so, much of the construction took place within and close to local housing. In particular, several of the vertical shafts that were needed to supply air and power had to be sited in residential areas. With work continuing around the clock the noise from site machinery was considerable, so containing the works-noise represented a significant challenge.

Solution

RVT Group was asked to provide noise control solutions, initially to contain the noise from generators, then later for a battery of compressors within a scaffold surround which were running throughout the night. To create a barrier that effectively blocked the sound, RVT Group deployed an array of 130 acoustic quilts, which provided up to 25.9 dB reduction in noise, as well as a Soundex Generator Exhaust Attenuator Box which dramatically reduced the impact of exhaust noise.

"The Shieldhall Tunnel project has been designed to have the least amount of impact on homes and businesses but when you are delivering a 5km tunnel under Scotland’s largest city, it is difficult to not have any impacts. The key is putting in procedures and measures that provide genuine mitigation and improvements.

Our need for RVT Group products stemmed from the need to run a slurry treatment plant 24 hours a day. While the main part of the plant is enclosed in an acoustic shed, the conveyor which removes the processed material to our storage area,
wasn’t enclosed.

We utilised the RVT Group barriers/blankets to reduce any noise from that conveyor. The blankets did their job and reduced the audible impacts, so they can’t be faulted. I have no complaints – we received good advice and had no real issues." - John McElroy - Costain