New screens firmly in place despite unprecedented storms
At a crucial stage of a £43M upgrade, including a critical inlet screen and screen handling replacement, the last thing a contractor would want is for not one, not two, but three back-to- back storm events.
Yet for one leading solution provider to the water industry, it provided the ultimate test for new inlet screens at Hartshill Sewage Treatment Works (STW) near Nuneaton in Warwickshire.
Since July 2022 (through to November 2024), MWH Treatment has been responsible for the design and integration of new inlet screens and screens handling, the expansion of the current primary and secondary treatment, and the addition of a new tertiary treatment and a sludge treatment system at the STW.
This important STW is an all-flows- works, being upgraded as part of proactive capital maintenance and in readiness for an additional 430l/s, which is to be pumped over from Hinckley in nearby Leicestershire to create a total flow of 1560l/s.
Working to reduce steel and concrete use where possible, Severn Trent Water and MWH Treatment wanted to reuse the existing inlet structure – removing the need for any new civils, or modifications to the existing assembly, which would have increased the programme of works substantially, adding to costs, environmental impact and health & safety risks. Using 3D digital models to increase on-site productivity, and with the benefit of wastewater handling solutions specialist SPIRAC’s vertical, space-saving screens able to reach 2m down (rather than a restrictive 1m), the inlet was meticulously planned out in the virtual space. This has made it much easier and more economical to fine-tune the design rather than have equipment arrive on site only to be sent away again for modifications.
“From the start, SPIRAC assigned a dedicated team so we could have continuity and clear lines of communication,” said Vince Walker from MWH Treatment. “Leading up to the pressure of the switchovers from old to new equipment we were regularly sharing our computer screens with SPIRAC’s Projects & Technical team so that the new temporary launder systems would keep us online and that we could be certain that the final screens would be spot on – pre-assembled, tested, ready to slot right in. In the meantime, SPIRAC removed all the redundant equipment and supplied us with a new control philosophy for the new screens and compactors.”
Vince added: “It seems easy to say now, especially with the foul weather after the commissioning works, but this is where planning and collaboration is so important. In a carefully managed, phased approach, we had five separate stages of switching over. SPIRAC ensured that flows were maintained, but with no loss of screening.”
The SPIRAC system has been integrated into the Hartshill treatment works system for the past six months, facing persistent heavy rain. This has proved that the new screens could do their job. Overall, the throughput has been increased by 200 l/s, but they are working as expected and with their self-cleaning design, only basic maintenance is required.
