Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | NOVEMBER 2016 | 31 In the know Digging deeper: Pipes and pipelines With the dangers of lead in water highlighted recently by the case of the US city of Flint in Michigan, pipe expert Nick Preston outlines the latest industry thinking on lead pipe rehabilitation Nick PrestoN PIPELINE CONSULTANT AqUAM CORPORATION drink and free from contamination with lead leached from their pipework. Multifaceted research In 1994, UK water company North West Water (now United Utilities) started a portfolio of research and technology projects aimed to significantly reduce the exposure of customers to lead in water supplies. Projects were undertaken on a range of topics: to replace the lead service pipes with minimal disruption, to line lead pipes with barriers and to adjust the water chemistry to limit its plumbosolvency – the extent to which water picks up lead molecules from lead pipe. The AWWA funded a project to generate a document that would enable water utilities and their contractors to select lowest whole-life cost, most technically appropriate solutions to end a customer's exposure to lead in their water supply. North West Water provided an industry expert for the Project Advisory Committee and supported case and field studies on which the research was based. In addition to the comprehensive research report a working document Lead Pipe Rehabilitation and Replacement Techniques was produced. regulatory changes In the period since the research was carried out, the World Health Organisation (WHO), the US Environment Protection Agency (EPA), the EU and their associated national regulatory bodies have all reduced regulatory limits from 50 micrograms per litre. They were first reduced to 25 micrograms and then most recently to 10 micrograms in 2015. Variations in methods of taking samples from customers' taps mean there are different implications relating to the actual exposure of a particular customer. For example, the US Lead & Copper Rule methodology is significantly different to that used in the EU and Canada. Variations may include whether water is stagnated in the pipe or flushed before sampling; the volume of the sample and other parameters of the property; and the statistical methodology of random pipe or property selection. Utilities found that an adjustment of pH, improvements in water quality (including colour and turbidity) and also the introduction of phosphate An operative relining lead pipes using the Serline system from Aquam I t is 15 years since the landmark report, Lead Pipe Rehabilitation and Replacement Techniques (2001), was published by the American Water Works Association (AWWA). Since its publication, there have been significant changes to global and national regulatory limits for lead in drinking water as scientists have become better informed about the risk posed to public health, especially in young children's brain development. The issue has risen swi›ly up the news agenda in recent months following revelations of exposure to lead in drinking water by people living in the US city of Flint, Michigan. Importantly for utilities concerned about their exposure to risk and wanting to take action, there has also been significant development and commercialisation of viable technologies for pipeline rehabilitation, which have yet to be widely adopted by utilities and their supply chain contractors. Public and local authorities, as well as owners and occupiers of public buildings, have a duty of care to ensure that the water is safe to Blocking leaden dangers