Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | SEPTEMBER 2017 | 23 For its new alternative water provision during incidents Thames is using the 'Always in Supply' (AiS) unit from Arlington, a variable speed, digitally- controlled pumping unit which is both portable and powerful. One or more AiS units can be combined with one or more AEWT storage units (a bag-in-box water tank which is already a familiar product to many in the UK water industry), to create a modular, ‚ exible system that can respond to events of all sizes. The tanks are set up close to the chosen „ ll point (e.g. hydrant, boundary box) and „ lled from the main prior to the shut occurring. Once the tanks have been „ lled, they can be connected back to the point from which the water has just been taken via the AiS unit. The integrated pressure gauge within the pump indicates the current pressure in the main; the pump can then be set slightly below that pressure and le‡ on standby. As soon as the shut is actioned, any reduction in pressure from demand in the main will be instantly and seamlessly met by the AiS unit. "The technology inside the pump product that we developed is relatively new, and has only recently been packaged in a way that we could use it," says George Lewis, Sales and Marketing Manager at Arlington. "The pumps are digitally controlled and use a 240-volt, three stage motor which enables them to be variable speed. This is important because if you connect a pipe to the network and suddenly pump water into it, you can cause all sorts of pressure transients and pressure waves which may cause damage to the pipes. By contrast, our system starts from zero, and " THE KIT a tanker and use that as the reservoir, with our pumps. The only problem with that is that in an emergency situation, tankers are suddenly very in demand, as are drivers, and everybody is a‡ er that resource. So by setting up our little water stations, you can then do a milk round and „ ll them up. That's a much better use of that resource then tying the tankers to a particular area." In a large scale loss of supply due to an emergency incident, the water stations could be concentrated on sites such as schools or old people's homes, helping to minimise disruption to vulnerable customers. if you only need a little bit of water, it will only give you a little bit of water, based on the pressure you want to maintain." A single AiS unit is capable of meeting the usual demand placed on the network by up to 100 homes operating at 2.5-3 bar in pressure. However, the beauty of the system is its modular nature, with any number of pumps and tanks able to be deployed in combination, explains Lewis. "We can daisy chain our tanks together, but we can also daisy chain the pumps together, if you need more ‚ ow. The clever part is that the pumps use Bluetooth so that they act as a single unit - they don't have to be physically connected. I could be pumping into one part of the network, and then I could set up another water station and pump into another part of the network 100 yards up the road, and I can build that into a temporary infrastructure to create a mini reservoir of water. "You don't have to use the tanks: there's no reason why you couldn't park An AEWT tank arrives as a fl at-pack AiS pumping unit The Works: alternative water Operational AEWT tank Multiple tanks can be daisy chained together for planned or unplanned incidents