Twinstore has the Edge on functionality

Adding functionality to double the role of an attenuation system is a guaranteed way to win over clients, as Tubosider have proven again at Edge Hill University in Lancashire.

The 125 year old university has been undergoing massive development in the last decade, and now has over 24,000 full and part time students – besides employing over 3000 people and contributing more than £175 million to the North West economy.

The latest £30 million extension is a new landmark sporting complex, providing an eight-court indoor sports hall and a 25m swimming pool contained within a new building. The whole complex is surrounded by a range of part floodlit natural and synthetic playing pitches, games courts and an athletics track.

The whole development was to incorporate sustainable drainage and low carbon design and building technologies. So for the stormwater attenuation, Tubosider were able to offer just what the project needed – one multi-purpose Twinstore system also incorporating water harvesting and irrigation.

This is the first system of its type installed by groundworks contractor S & J Charnley on any of the previous developments at Edge Hill over the last 10 years.

“What the Twinstore system provided was not just attenuation to add to the infiltration required for the project, but year-round management of the irrigation system for the five sports pitches, right from seed germination,” says Jim Charnley.

“With a 250 m³ capacity for irrigation at the base of the tank, and an irrigation day tank installed, the inbuilt flow regulator limits outflow to 15 liters/second on a 1.4 meter head – the discharge limit specified. And the tank is all within a footprint of 18.4 meters max by 89 meters, so compact and easy to monitor via its two access shafts, one at each end.”

In this case using 150 mm below the tank as a sump, with finer granular material than the remainder of the fill above, the Edge Hill system has all the classic attributes of Twinstore.

By balancing the amount of captured water between the tank itself and the impermeably lined surrounding fill, it can store considerably more water than conventional systems in a comparable space. The alternative here would have been a larger conventional tank with a higher outlet, but Twinstore was adopted as the best solution.

The final solution is yet another example of value engineering by Tubosider’s technical sales and design teams. With a tank of 1400 mm diameter pipe and a gross capacity of 1174 m³, almost a quarter is devoted to harvesting, the remaining 924 m³ of capacity being dedicated to attenuation.

As in previous phases of the Edge Hill construction programme, S & J Charnley are due to complete all the groundworks for the remaining three years of development. John Turner Construction of Preston will then install and commission the remaining building and works.

Besides the new sports complex with its 100-station fitness suite, aerobics studio, health suite with sauna and steam rooms, café and lounge area, new ecological features and wildlife habitats will be created. These include mixed-woodland areas and footpaths linking to Ruff Wood, wildflower meadows, open grassland and a new wildlife pond.