WET News

12 WET NEWS APRIL 2016 ONSITE ScReenIngS RefuRbIShment A direct piping link connected the SRP units, enabling each unit to take up additional flow capacity if required manual valves were incorporated to isolate flows should a SRP unit fail. Inset: each control panel has telemetry links to alert immediately of equipment failures Upgrading with zero impact • A refurbishment programme at Wessex Water's Portbury treatment works required strict guidelines to be met. Was a packaged plant solution the answer? projEcT SpEcS • minimise impact of hire equipment installation and operation on refurbishment programme • Provide equipment to comfortably handle potential flow rates of 550l/ sec • Provide equipment to comfortably handle potential flow rates of 550l/ sec • Operating costs and environmental responsibilities must be considered A s part of a planned refur- bishment programme at its Portbury sewage treatment works, Wessex Water brought in Nomenca to under- take the removal and replace- ment of old screening and screenings handling equip- ment at the Inlet Works. To enable the inlet works to main- tain operational capacity over the duration of the planned works Nomenca partnered with M&N Electrical & Mechanical Services' Hire division to pro- vide a packaged plant solution, enabling the work to be carried out onsite with no disruption to operational stability during the installation of the new screens. To manage the flow rates imposed by the sewage treat- ment works, address the zero unscreened discharge specifica- tions and minimise the impact of temporary equipment on Nomenca's site activities, M&N put a series of options through their SolidWorks modelling platform prior to making their selection. Following rigorous simulation tests and the inclu- sion of additional bolt-ons to meet the screening criteria, M&N put forward its flexible Screenings Removal Plant unit with additional modifications for consideration. M&N's dedicated SRP 'Pack- aged Plant' units were designed and manufactured in-house to provide a flexible wastewater screening solution that can be rapidly deployed to site, pro- viding operational stability, with minimal disruption to site infrastructure. The SRP unit selected for the task comprised a main inlet tank housing an FSM Frankenberger 6mm perforated band screen, spray bar and self-adjusting brush head alongside a Kuhn KWP 400/1200 HD wash press. To ensure Wessex Water's zero discharge specifications against maximum wastewater flows of 550l/sec, M&N's hire team designated two SRP 450 units to work in conjunction with each other. To remove the need for pumps to feed the screening equipment two 450mm exit channels were core drilled at the main inlet chamber. Using gravity to feed the equipment saved Wessex Water money both in terms of additional equipment hire and the need for 'standalone' power supplies on site. Flows Each exit channel fed the individual SRP units via dedicated pipework. Manual valves were incorporated at this early stage of the installation infrastructure to enable the onsite team to quickly isolate the flows in the unlikely event of either SRP unit failing. With both exit channels open throughout the period of the installation the subsequent individual screenings handling created less of a burden on each SRP, significantly reducing energy consumption whilst maximising the quality of handled materials and subsequent liquid passed to the outlet point. To ensure that Wessex Water's discharge policy was met M&N designed the installation to incorporate the following bespoke additions: • The SRP 450's standard bypass flows were capped off • The SRP 450 units were connected via a direct piping link to allow each unit to take up additional flow capacity from the other if required • Each control panel was designed by M&N with telemetry links to immediately alert M&N, Nomenca and Wessex Water personnel by mobile phone in the event of any equipment failures • Pipes connected each SRP 450 to a dedicated handrake tank, acting as a manual backup resource further ensuring no wastewater was bypassed. To remove the need for generators to be brought to site a power supply was from the existing Motor Control Centre. This was deemed a more environmentally conscious option over the course of the refurbishment programme. All elements of the functionality of the SRP units were monitored round-the- clock via telemetry by M&N's expert engineers at the company's Portland headquarters. Each control panel was created specifically for the Portbury assignment, constantly monitoring flow & level rates alongside intricate functionality mechanics. The set up was designed to offer easy access to all elements of the hire equipment, including specially created platforms for the handrake tanks. Nomenca core drilled a 300mm entry channel to the outlet point so that the SRP 450 outlet pipes could be conveniently sited, ensuring minimal space was taken up by the installation from the main inlet chamber to the outlet point. Collaboration From approval of hire equipment specifications by both Wessex Water and Nomenca, M&N engineers were able to have the site installation completed in just five days. All equipment was delivered to Portbury using M&N's own transport and li›ing equipment and working in collaboration with Nomenca, both parties were able to deliver Wessex Water's requirements without negatively impacting on the operational effectiveness of the Portbury STW. Dave Shuttleworth, project engineer, Nomenca, says: "Two SRP450 Elevator screens have been installed at Portbury STW to enable the existing screens to be replaced as part of a capi- tal works Scheme for Wessex Water. M&N Electrical and Mechanical Services carried out the Supply, Installation and Commissioning of these temporary screens on behalf of Nomenca. "The professionalism and excellent Health & Safety culture of M&N's installation team could not be faulted. The reliability of the units also could not be faulted and callouts over the recent two- month period have been zero. I would certainly recommend the use of M&N's Screening Removal Plant units without hesitation on any future schemes"

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