Central to the latest contract was providing surface water mitigation to prevent the increased discharge of rainwater from the partially Greenfield development. The key to the drainage solution was to provide a suitable storage system which would provide the correct volume at the appropriate levels to allow the flow to be restricted off the site, whilst ensuring the development was free from flooding.
Consulting with Carey, previous partners on work for the plant, Rolton considered three possible solutions before deciding on Twinstore for a number of reasons – not least the smaller size and cost of tank.
“We were also constrained by the area available and the large diameter pipe coming into it,” says Rolton’s senior project engineer Shaun Pentlow.
“Tubosider’s shallower design saved us up to 20% in tank volume, and with the pipes being 2.8 meters in diameter, they were not only compatible with the incoming pipework, but could also be easily brought on site on a lowloader.”
Choosing Twinstore with its lighter weight but loadbearing strength also proved important in installation. Delays because of contaminated ground meant that delivery of the prefabricated tank sections had to be timed and managed to the day.
And as excavation had already taken place, the whole system had to be built from the bottom up instead of lowered into the trench and then filled around.
Carey’s site manager Richard Emery was already familiar with Tubosider systems and endorsed its choice. “Precast concrete would have been another online option but did not compete on price or handling, and a crate system would have meant an offline solution and again been more expensive and bulky.”
“The open jointed design of Twinstore tanks saved us space by balancing water storage between the tank and the Bentonite lined fill, so we only needed less than 1300 cubic meters of capacity in three legs of 55 meters.
“Also, tank delivery really became a key issue after previous delays in the project, but Tubosider were well on top of things and supplied us just when we needed.”