WET News

An early image of the Vartry scheme at Callowhill (courtesy of the National Library of Ireland) experiments with boring machines over the course of the project, but neither proved effective. To treat the water, seven filter beds – each featuring a 6, 6in layer of stones, gravel and sand – were initially established, largely by excavating into the rock, and a further three were added in 1873. Aer the supply scheme was up and running, Waterworks Committee chairman Dr John Gray declared that "this marvel has been achieved by high engi- neering genius and by the scarcely less necessary coopera- tion of hardy and honest indus- try", while Neville said in 1875 that it had "proved one of the most successful and effective works of the kind ever executed, and has given universal satisfac- tion to the citizens". James Joyce even wrote in surprising depth about its workings in his 1922 novel 'Ulysses'. The scheme grew to meet demand, with a third reservoir built at Stillorgan in 1885 and a second at Roundwood reservoir in 1923, while treatment evolved to include lime, chlorine and fluorine. Despite the various upgrades and extensions, though, it is the original Vartry water supply scheme – with the reservoirs, slow sand filtration plant, Callow- hill tunnel and 40km of trunk mains – that in essence continues to provide drinking water for around 200,000 people in Wick- low and south Dublin. The scheme now finds itself on the Environmental Protection Agency's Remedial Action List (RAL) and requires urgent improvement to meet drinking water regulations, while the Cal- lowhill tunnel – relied on by around 100,000 people – is in poor condition, with a 1995 struc- tural survey noting both that it was in danger of collapse and that leakage was posing a quality risk. To bring it up to standard, Irish Water has designed a four- part programme of works that will improve the existing draw- off tower and overflow spillway, provide a new link from Vartry to Callowhill and replace the water treatment plant. Veolia's treatment plant upgrade, which is due to be com- pleted in 2020, will ensure the scheme can meet drinking water standards and come off the RAL, providing a treatment capacity of 4,200m3 per hour for raw water and a treated water output of 4,000m3 per hour. It will make use of Veolia's Spidflow technology, which can treat reservoir water containing low density particles and algae, which has been an issue at Vartry during the late spring months. The €29 million project to replace the Callowhill tunnel, meanwhile, began in January, with the final section of the 4km pipeline laid in August. "The original pipeline was originally constructed in the 1860s and provided a reliable water source to the region, play- ing a significant role in reducing outbreaks of water-borne dis- ease," Minister of State for Food, Forestry and Horticulture Andrew Doyle said at the beginning of the Callowhill project. "The vision that built Vartry 150 years ago is echoed now as we continue to invest in the future." wwtonline.co.uk | SEPTEMBER 2018 WET NEWS 15 PROJECT SPECS • New Vartry WTP to be constructed by 2020 on site of existing WTP • New pumping station to be built at Vartry WTP • Decommission Callowhill tunnel to allow for remediation works • Replace nearly 4km of buried pipeline between Vartry and Callowhill • New break pressure tank to be built at Callowhill • Pipes and fittings within dam at Vartry reservoir to be replaced • Vartry dam spillway to be improved to allow for more intense rainfall events The route for the pipeline from Vartry to Callowhill 6765 m 3 2,7 m 3 /h 8° C HOW FUTURE- ORIENTED ARE YOUR INVEST- MENTS? HYDRUS 2.0 INDUSTRY SMART WATER METERING Begin digitalisation with confidence. We work with our customers to develop the perfect metering solution – flexible and tailor-made. The new HYDRUS 2.0 has been developed to offer best connectivity. OMS 4.0, IoT4metering and various interfaces come as standard. HYDRUS 2.0 also offers the highest levels of data security in accordance with the BSI (Bundesamt für Sicherheit in der Informationstechnik – German Federal Office for Internet Security). Also available as a bulk water meter. www.diehl.com/metering IN THE MOST DEMANDING ENVIRONMENTS

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