Water & Wastewater Treatment

WWT November 2016

Water & Wastewater Treatment Magazine

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Page 7 of 47

8 | NOVEMBER 2016 | WWT | www.wwtonline.co.uk Comment F or anybody not familiar with the little blue pellets adorning our front cover this month, they are made of one of the least popular substances in the water treatment in- dustry in recent years – metaldehyde. A commonly used pesticide for con- trolling slugs, metaldehyde is difficult and costly to remove from water, and when it is washed into watercourses during seasonal rains and ends up in drinking water, can lead to compli- ance failures. As we discover in our Innovation Zone feature this month (p24) the water industry is investigating or implement- ing a host of potential solutions to this thorny issue. Membranes and activated carbon filtration are among the treat- ment options, but the relative expense of Slugging it out these – Anglian Water recently estimated that it would cost £600M to install metal- dehyde treatment across its region - have meant that eliminating the chemical at source through catchment management initiatives has appeared the more attrac- tive option. However, such initiatives depend on the goodwill and competence of farmers, or the willingness of the industry to pay them incentives; and even given the above is in place, catchment approaches are always imbued with more inherent risk. For this reason, there was strong support among participants at the recent WWT Drinking Water Quality Conference (see report, p12) for the government to consider a ban on metaldehyde. With alternatives available – albeit at slightly greater expense - in the form of ferric phosphate pellets, water quality experts at the conference in Birmingham felt that on this issue at least, it was time for regulators to help enforce change rather than rely on incentives and partner- ship working. "We have been working with carrots, but is it time to talk about sticks?" one delegate asked. While the levels of metaldehyde that James brockett eDItor JamesBrockett@fav-house.com Twitter: @wwtmag Industry view sponsored by alex stephenson market Development Director Hydro International Do we really need another SuDS review? We've had plenty already, and the case for Sustainable Drainage Systems is well proven: they are cost-effective, practical, multi-functional and can bring biodiver- sity and amenity. So why do we keep going around in circles with SuDS policy? Why is it taking so long to implement simple and effective guidelines that ensure sustainable surface water drainage is used consistently on new developments and retrofitted into existing infrastructure? Next year we'll get another SuDS review; the UK Government is committed to reviewing the effectiveness of its recently-introduced policy to deliver SuDS through planning in England. However, there's no guarantee that anything will change. Around in Circles with SuDS I've watched the SuDS merry-go- round for decades, as convenor of British Water's Sustainable Water Management Group, and it's clear to me there are some clear sticking points. As long as these are le unresolved, we will keep going back to square one. Firstly, there is no commonly held and definitive definition of SuDS; this leads to misinterpretation, especially among the general public and some politicians. There are those who see SuDS as the same as flood control - which they are not. Some interpret SuDS as 'natural' or above-ground features only, which they are not. A good definition of a SuDS scheme is one that mimics natural drainage paths and processes, managing both water quantity and quality to achieve sustainable outcomes: SuDS schemes protect property and the surrounding environment, as well as preventing storm flows from overloading the sewer network and being handled unnecessarily at the wastewater treatment works. What constitutes the best means to achieve these sustainable outcomes is a matter for science and engineering. Any drainage system must be precision- controlled and regularly monitored if it is to achieve measurable performance targets. Otherwise no-one knows if the surface water drainage system is working as designed, or when it should be maintained. Therefore, a toolbox of SuDS techniques, including proprietary systems and manufactured components, must be available according to site-specific opportunities, the soil and ground conditions and the topography of a site. As developers are pressured to accelerate building of much-needed homes in the UK, the hard commercial choices they have to make in terms of land-take and construction costs can be mitigated with a full SuDS toolbox. Developers also need confidence they can hand over ownership of SuDS schemes to the adopting authority. Any review should aim for full clarity around which authorities should have a duty to own SuDS in future, with clear technical guidelines for repeatable, predictable maintenance. Only then will we stop going around in circles. www.hydro-int.com tend to cause compliance failures are not generally high enough to be injurious to health, drinking water standards are there for a reason and there is no case for relaxing them, even once the UK has undergone Brexit. Instead, it is time the government and the Environment Agency took the issue seriously and listened to what the water industry is telling them loud and clear. The counter-argument from the farm- ing lobby, of course, is that regulation is a blunt instrument for achieving change and that any additional cost incurred through the enforced use of more expen- sive pesticides would be passed on to the consumer of food through higher prices in the supermarket. But the money involved would surely be a reasonable price to pay when set against the alterna- tive of capital investment in end-of-pipe treatment solutions. While catchment management practices are a crucial part of the water sector's armoury and will no doubt continue to principally involve carrots (and juicy, slug-free carrots at that) it does seem that in this particular arena the carrot could be helped along with a dose of regulatory stick.

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