WET News

TECHKNOW • The new process marks a significant step away from chemical and energy intensive traditional technology • The new process is very efficient and has a smaller footprint than conventional treatment technology • The ion exchange technology only consumes salt and the resin used can be recycled many times for several years NEED TO KNOW 1 The new works will be capable of producing up to 90Ml of drinking water daily 2 Plymouth has grown significantly and what was a rural works has been absorbed into a busy city 3 The site is extremely constrained, which makes operation and access difficult 4 Water now has to be pumped from Crownhill up to Belliver Service Reservoir to supply 14,500 properties THE VERDICT The new process is very efficient and has a smaller footprint than conventional treatment technology. to come. The Mayflower project is complex and includes a range of infrastructure and non-infrastructure asset groups membranes: • An unlimited life (meaning no replacement costs) • No fibres that can break • The ability to backwash at very high pressures (improved cleaning) • Stable water throughput over its lifetime The process can treat a wider range of raw water quality from almost any source. This is important because we are starting to see the early impacts of climate change on raw water quality, which is deteriorating all over northern Europe. The construction site at Roborough Down, on the edge of Dartmoor National Park, has a history of water treatment dating back 118 years. The south-west corner of the current site was bought by the then Plymouth Corporation in 1898 and an early water treatment works was located on the site before Crownhill was built. This piece of land was inherited by the South West Water Authority in 1974 and then South West Water in 1989. SWW purchased two further parcels of land in 1991 for the site's current raw water tank, which feeds Crownhill and Littlehempston WTWs, and a proposed treatment works to supplement Crownhill WTW, which was never built. Since Crownhill was built in the early 1950s, the city of Plymouth has grown and much of the new development has been on the higher ground to the north and east of the treatment works. Consequently, water now has to be pumped from Crownhill up to Belliver Service Reservoir to supply 14,500 properties (40,000 population). The new site will enable water to gravitate to a wider area, which reduces costs and lowers the carbon footprint. The Mayflower project is complex and includes a range of infrastructure and non- infrastructure asset groups including raw water mains, intake pump stations and the water distribution system. As part of the project, a new 7km treated water main will be laid, following the route of the existing raw water main, from the new treatment works to Crownhill, where it will connect into the distribution network. Over the course of the project the following materials will be used: • 20,000 tonnes of aggregates • 4,500m³ of concrete • 410 tonnes of steel reinforcement • 7km of off-site pipeline • 2km of onsite pipe work • 3km of cable ducts • 80,000 tonnes of earth The construction phase is scheduled to finish in March 2018. The works will become operational in September pro- ducing up to 90ML of drinking water every day. JUNE 2017 WET NEWS 9 Crownhill looked very different back in the 1960s £174.94 PER LINEAR METRE* *Figure quoted is the difference between Class S (Plastic Flexible Pipe) and Class N (Concrete Rigid Pipe) costs, based on a DN1800 pipe. Potential cost savings are based on normal ground conditions, including granular bedding costs of £15 per tonne and cost of material being taken off-site to landfill at £6 per tonne (figure shown is independent of pipe costs). The bulk density of granular bedding material is assumed to be 2.2 and for excavated material is assumed to be 2.0. Plastic Flexible Pipe with granular surround (Class s Bedding) Concrete Rigid Pipe (Class N Bedding) 01530 240000 | 028 7964 2558 sales@fpmccann.co.uk fpmccann.co.uk/drainage For further details on the materials cost calculator visit: concretepipes.co.uk/calculators/material-cost continuous battery powered turbidity for network monitoring t. 0800 8046 continuous battery powered turbidity for network monitoring t. 0800 8046 062 www.atiuk.com e. sales@atiuk.com

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