WESSEX Water has started work to extend the Allington Reservoir in Wiltshire as part of a programme to improve supply without developing new resources.
The £3.5m scheme is being carried out by main contractor May Gurney and will increase the reservoir’s capacity by five million litres. Problems with the integrity of the existing pipeline used for the clean-out of the reservoir – combined with the increased capacity from the extension of Allington – meant the pipeline needed to be replaced as part of the upgrade. The new 1.8km pipeline will serve the existing reservoir and the extension, discharging the water from the clean out operation into a larger stream further away from the site.
Materials suppliers were involved during the design period to stimulate innovative proposals and promote savings. Pipe specified during the feasibility stage and manufactured by GPS PE Pipe Systems was delivered to site in just four vehicle loads, as Alex Brownlow from May Gurney explained: “By providing pipe in longer lengths [18 metres] the supplier helped us reduce the number of deliveries and on-site welds by 30%. The reduced number of joints also helps underpin pipeline integrity.”
Pipe lengths were joined by butt fusion welding and at road crossings by Durafuse electrofusion couplers. The 18mm pipe wall has made the jointing process still quicker while providing a sufficient pressure rating for the required flow rate.
May Gurney’s team installed the pipe in an open cut operation and the durability and flexibility of the pipe brought operational advantages, as Brownlow continued: “In some areas the trenches are around 3.5 metres deep so specification of tough yet flexible Excel PE100 pipe made pipe laying easier and faster.”
The upgrade is due for completion before Christmas and will form an important element in the Wessex Water eight-year ‘Water Supply Grid’ scheme, which includes a total of 20 projects across Somerset, Wiltshire and Dorset.
Image – Using longer pipe allowed deliveries to be reduced.
