Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | SEPTEMBER 2014 | 41 Digging deeper Zero Leakage, Zero Excavations. Utopian dream or future reality? U nderground. It's not a subject which many people think about – un- less they work in a networks or the transport business. However, when roadworks spring up on the daily com- mute, or an essential utility supply is interrupted to a home or business, customers' thoughts do jump to their utility providers. The truth is that it's busy underground with complex networks of gas, water, wastewater, communications and electri- cal conduits, including the transport network in London. Understanding and mapping, not to mention managing, so many physically overlapping net- works – ensuring that all of them are in reasonable condition and providing excellent customer service – is a complex task, particularly as each network is managed largely in isolation. The National Joint Utilities Group (NJUG) represents utilities and their contractors, promoting best practice and seeking to drive up standards of road and street works in the UK, but maybe it is time to take a more joined up pan-utility approach in other areas too? This article highlights a few topical areas of current in- terest to WRc, namely: water ingress to gas mains; developments in pipeline condition assessment technology; and the need to improve the integrity of PE pipelines in the water sector. Consumer service paradox Sections 81 and 82 of the New Roads and Street- works Act 1991 (as amended) confers a duty on utility companies to maintain their assets in good working order and compensate street authorities or other utilities where remedial costs have been incurred by one utility as a result of another util- ity's failure to maintain its assets. Whether it is as a result of some recent winters' inclement weather or greater media coverage is immaterial; it is clear that the level of scrutiny being applied to water mains failures which have led to gas service interruptions has increased significantly. Whilst the number of incidents per year is thankfully relatively low, the consequences of each incident – for both consum- ers and utility companies – are potentially huge. We believe this is a clear instance where the Ofwat The level of scrut- ing being applied to water mains failures which have led to gas service interruptions has increased signifi- cantly From cross-utility co-operation to PE pipe joins, the challenges surrounding leakage and its reduction in the UK water network are numerous, but, says WRc, "the size of the prize is huge". service incentive mechanism (SIM) appears at odds with the wider needs of consumers. At present, water companies are incentivised to minimise in- terruptions and hence will maintain the supply to consumers during a burst event until the company is ready to effect the repair. Any supply interrup- tion is minimised to avoid reputational damage, unwanted customer complaints and payments to customers which would be triggered if the supply were turned off for too long. However, this continu- ous leak flow increases the likelihood (in favour- able conditions) that a nearby gas main can fill up with water, and interrupt the gas supply to the same set of consumers! Given the choice, custom- ers may choose to go without water for a planned time rather than lose gas for a longer time during a cold winter. The costs of purging the gas mains and services, and checking household appliances are safe to use can be substantial. No wonder the gas distribution network operators are looking to recover their incident costs from water companies. We think greater co-ordination of asset location and condition data between water and gas utilities is a necessary way forward to solve this paradox. Prone locations where gas mains could be at risk from high groundwater levels and leakage from nearby water mains would serve as an alternative measure of the response time required for water companies to respond to incidents at that location and contact the gas distribution network operator at an early stage if required. This is not an issue that can be solved through legal action. ► Mark Smith, WRc managing director Mark Kowlaski, WRc senior consultant

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