Lining technology aids pumping station upgrade in Scotland

[Case Study, August 2009] -- Peterhead is a world renowned fishing port which lies on the east coast of Scotland some 30 miles north of Aberdeen. As part of a program of works on the town's sewer network a pumping station was being upgraded...

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[Case Study, August 2009] -- A Scottish Water pumping station with a history of bursting was recently upgraded as part of a programme of works on the town’s sewer network in Peterhead, a world renowned fishing port which lies on the east coast of Scotland approximately 30 miles north of Aberdeen.

The station includes two 600mm diameter PVC sewer mains located mainly alongside South Road in Peterhead. Approximately 200 meters of the main run beneath the road side grass verge and the final 200 meters run beneath the road carriageway.

After examining the options available for the rehabilitation of the PVC mains, Scottish Water decided the best option would be the installation of a structural, close-fit liner within the existing pipe. Ultimately Insituform Technologies Ltd.’s (“ITL”) InsituGuard™ lining system was selected to complete the work. The lining operation was to be completed by ITL, working in close cooperation with John Gibbons, a local contractor who completed the civil works.

The InsituGuard™ lining system is used to renew distribution and trunk water mains up to 1600mm in diameter and reduces digging and disruption while helping water companies reduce water loss and improve water quality. The InsitGuard™ system was selected because the liner offers an easy installation system resulting in the required close-fit liner, thereby allowing the renovated pipe bore to be maximised.

The gravel/stone materials cleared from the host pipe which had hindered the cleaning works on the first sewer main.

INSITUGUARD™ INSTALLATION
Trial pits were excavated to confirm the depth and alignment of the two PVC mains. In order for ITL to confirm and correctly match the internal diameter of the PVC pipes, sections were cut out of both mains.

After arriving on site, the first task for ITL was to clean out and survey the existing pipe using closed-circuit video inspection to ensure that no obstructions would hinder the liner installation. During the cleaning of the first main, the cleaning crew encountered a problem in the amount of stones that were found within the pipeline. As cleaning progressed, the build-up of stones prevented the crew from completing the winch-through. Excavation was necessary in order to remove the build up of stones and debris.

Once cleaning was completed and the video survey showed no other obstructions, ITL prepared the required liner pipe for insertion into the main by using its InsituFold™ machine, which alters the shape of the InsituGuard™ liner into its classic ‘U’ shape. For each installation shot, the liner was fused into suitable lengths and transferred onto rollers before being pushed through the InsituFold™ machine. The prepared pipe was then directly inserted into the host pipe. For each lining run a winch was utilised to pull the InsituGuard™ liner through the host pipe.

For each installation shot, the liner was fused together into the required liner lengths using a fusion unit which was adjusted to suit the 555mm diameter of the InsituGuard™ liner. In all, five installation shots were required to complete the rehabilitation work. Individual shot lengths were 254m, 204m, 205m, 189m and 201m.

The folded liner pipe entering one of the host pipeline sections.

The arrival of the liner pipe at the reception pit at the end of the installation pull-in.

Work started on the first of the lining sections in early May 2008. However due to open cut works which needed to be completed in order to meet the requirements of the production schedule, ITL left the site in July 2008. Once the open cut works were completed, the first sewer main could be commissioned. ITL then returned to site on 3 November 2008 to complete the remaining lining works. The company completed all works and was off the jobsite by 19 December 2008.

Scottish Water representatives commented that they were very pleased with the progress of the works and the final outcome, and with ITL completing additional works.

Commenting on the project Insituform’s site agent Mike Bake said: “Because the level of muck in the first main prevented full cleaning the first time, this project was challenging. All parties worked well together with great effect and ultimately ITL was able to rehabilitate the sewer mains to the standards the client wanted and to the complete satisfaction of all other concerned parties.”

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