Dec. 12, 2011
-- The 75,000m2 distribution centre will serve the supermarket chain’s network of stores in the South West and forms part of an £11 million regeneration scheme, including up to 2,000 new homes. The development is located on a mixed brownfield and greenfield site, which combines redundant industrial land with farmland. The mains connection for the scheme has been made at the front of the site where there is a railway line and a chemical factory, which lead to concerns about contamination.
Explains Bob Wood from Wessex Water: “While stringent controls and operational best practice limit the contaminants from the factory now, historically they have been varied and significant. Trial holes were tested across the site to ascertain the level of contamination and, while the contaminants were not found over a large proportion of the site, the high water table caused by the tidal nature of the River Parret local to the site does present the risk of migration of contaminants across a wider area.”
It was these concerns over the potential for contaminants to be carried to ‘safe’ soil areas by tidal waters on the flood plain site that prompted Wessex Water to specify 355mm Protecta-Line pipe for a new main running across the distribution centre site, including the footprint of the building and access roads. Around 1,200m of Protecta-Line was used in SDR17, providing up to 10 bar pressure capability which allows for additional capacity to be factored into the installation.
Wessex Water installed the pipe into open trenches, incorporating T-joints to allow take-offs of supply to be added at a future date. All joints were made by butt-fusion and the installation team prepared the pipes using the Protecta-Line Surprep tool to scrape away the outer layers. Wessex Water continued its practice of wrapping the joints using aluminium foil and Denso tape throughout the Protecta-Line installation. Away from the Protecta-Line spine main, the site is not at risk of contamination so ordinary HPPE pipe was used with steel mechanical fittings to create the joints between the two materials.
Bob adds: “Even a small risk of contaminant migration makes it prudent to specify an effective barrier pipe. Protecta-
Line safeguards against ingress of all known contaminants and is our preferred barrier pipe solution so this specification means that we can be confident of a safe water supply, whatever the ground conditions.”