Water & Wastewater Treatment Magazine
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• CASE STUDY 14 | FEBRUARY 2018 | WWT | www.wwtonline.co.uk modelling was also used by construction teams, as well as for community engage- ment with local residents and council planning application meetings. The technology meant almost every design detail could be checked right at the outset, from the tie-ins to existing service mains and drainage to the location and dimensions of cable ducts and draw pits. The building process With detailed designs approved, the AutoCAD model of the upgrade work was laid over the site survey model - ensuring equipment built off site would fit perfectly once in position. This process immedi- ately highlighted where small design tweaks were needed. Dealing with these onsite – as would normally be the case – would have inevitably caused delays and increased costs. The offsite build took place at No- menca's specialist facilities in Warrington. An SR4-rated kiosk was developed to house the UV and hypochlorite dosing systems, through which raw water from the boreholes would be pumped at mains supply pressure. It holds an additional booster pump to an auxiliary reservoir too in case of a network shortage along with other ancillary equipment, building services and the heating and ventilation systems. in the UK water industry, as well as help- ing to overcome safety and operational challenges." Virtual planning BIM technology was intrinsic to project delivery from the outset. Nomenca and Affinity Water shared a virtual view of the site and collaborated online to develop a detailed job scope – reducing the need for the 500-mile round trip to the site. A 3D laser scan using a FARO focus scanner captured the dimensions and positions of all assets on the site. Buried services were then mapped with ground- penetrating radar, and the results brought together to produce a 3D AutoCAD model. With the extent of the works reviewed, next came a detailed, working 3D design model built within a multi-disciplined Common Data Environment. The model incorporated all the major and minor components and their various inter- connections. It featured the chemical treatment plant and borehole pumping kiosks with their pipework, steelwork and electrical installations, the diesel genera- tor and fill point kiosk, and the chemical delivery area along with its drainage, valve chambers and blind tank. Nomenca's in-house virtual reality so–ware enabled Affinity Water to walk through the proposed design. The virtual T aking a pioneering new approach to a borehole pumping station upgrade in Essex, Affinity Water minimised asset downtime and costs using a strategic offsite build programme. The ambitious project combined virtual design technology with modular offsite manufacturing - shi–ing the mainstay of the construction work to a controlled factory environment. The challenge The borehole pumping station and water treatment works supplies 120,000 houses in Saffron Walden and surround- ing villages via a nearby reservoir. Rated at 14Ml/day, water is disinfected using hypochlorite dosing and a contact tank then boosted to 9 bar into supply and to a remote reservoir. To ensure the plant continued to operate at full capacity for the area, Affinity Water needed to replace existing equipment with a new and efficient installation. Due to limited shutdowns being feasible at the facility, the existing plant would ideally need to remain operational right up until the new equipment had been commissioned and tested – some- thing that would be hard to achieve using traditional on-site techniques. Affinity Water awarded specialist contractor Nomenca the design and build contract for the new plant. Nomenca pro- posed an innovative technical approach to the project, employing its Skilled Assembly Factory Environment (SAFE) modular construction. Moving the building process away from the physical site and into a con- trolled offsite environment can have many benefits, from improved health and safety to lower costs. While offsite construction is yet to become the norm for the water industry, it is growing in popularity. Nomenca has already brought its SAFE approach to a number of projects but Affinity Water's Essex pumping station was the most ambitious project yet. Gavin Stonard, Engineering Director at Nomenca said: "Offsite construction tech- niques are in a growth period worldwide – and already delivering efficiency savings Offsite build for Affinity pumping station The Works: offsite construction The pumping station was built and delivered in a self-contained kiosk