Utility Week

Utility Week 25th October

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Page 23 of 31

Operations & Assets Market view Come rain or shine Thomas Francis argues that water companies need to take a less patchy and more proactive approach to managing weather impacts. I Winters: The Met Office's preliminary research suggests we are getting more rain and we are seeing a change in the nature of the rain we get, with extreme daily rainfall becoming slightly more frequent, most notably during the winter season. Winter impacts have been particularly significant in recent years. After more than a decade of relatively mild winters prior to 2008, the winter of 2010/11 was especially severe (see graph). Significant falls in temperature over several weeks caused pipes to freeze at treatment works, increased pipe leakage and bursts – leading to massive demand on the network – and made access to assets and customers difficult. The increase in pipe bursts caused considerable operational difficulties for water companies, including fluctuations in workload and resources. The impact was exacerbated when the subsequent thaw at the end of the cold spell led to many burst pipes and other asset failures. The large volumes of customer calls 24 | 25th - 31st October 2013 | UTILITY WEEK 15.0 10.0 UK minimum temperature (oC) n recent years, the UK has seen extremes of weather with four out of the last five winters being colder and drier than average. The winter of 2011/12 saw above average temperatures but was followed by the wettest April on record, and the wettest summer in 100 years. In fact, five out of the last six UK summers had above average rainfall (2010 is the exception), leading to localised flooding and disruption. Weather extremes are severely affecting the water industry, and swings from one weather event to another can pose significant challenges for water utilities. In an industry that relies on the natural environment to satisfy customers' demand for water and to process the subsequent sewage output, any disruption in this environment is likely to have consequences spanning across the whole business. The operational and financial performance of a water company is inextricably linked to weather conditions, which affect asset serviceability and maintenance, and long-term strategic planning and investment decisions. 5.0 0.0 -5.0 -10.0 -15.0 01 Nov 15 Nov 29 Nov 13 Dec 27 Dec UK minimum temperature 1981-2012 long-term average 10 Jan 24 Jan 07 Feb 21 Feb 2011/11 UK minimum temperature Graph: prolonged drop in minimum temperature in winter 2011 received, particularly during the Christmas and New Year holiday period, compounded pressure on staff and led to unplanned overtime. Additionally, the reduced effectiveness of biological sewage treatment posed the potential risk of missing environmental consents. The graph shows a prolonged drop in UK minimum temperature during the winter of 2010 /11 in comparison with the long-term average (1981-2010) Summers: A look at the weather (rainfall and temperature) experienced in recent summers highlights the different challenges the water industry faces year on year, which in turn can have a significant impact on resources. For example, 2012 was a summer of cool temperatures and above average rainfall. Although demand for water was reduced, rainfall caused widespread river and surface water flooding, threatening treatment works and other assets. Other impacts included property flooding from overloaded sewers and a higher than average number of pollution events. Financially, the impacts of this rainfall were significant for UK water companies with the increase in the number of houses on their DG5 register. As the summer progressed, the impacts of one in five or even one in ten year rainfall events were having an unprecedented impact on property flooding because of very high ground saturation. Analysis by the Met Office shows that the prolonged rainfall throughout the summer produced antecedent wetness conditions, which modified the impacts of relatively frequent subsequent rainfall events to reflect

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