A precast concrete holding tank from Kijlstra’s Vario range has helped contractors knock weeks off a programme to upgrade a waste transfer station on Merseyside.
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Local contractor LCM Group was employed by waste firm Biffa to install a new underground liquid waste storage tank at the site in St Helens. The tank receives and stores liquid run-off from food waste delivered to the transfer station. When the tank is full, it is pumped out and tankered away for disposal.
“The client’s signature idea was to install a lightweight glass-reinforced plastic [GRP] holding tank,” says Kijlstra contracts manager Steve Gainsley. In theory, a GRP tank is light, easy to handle and requires no special lifting equipment to install.
“The problem is, the specification required the tank to be supported and contained within concrete poured in-situ,” explains Steve. This required formwork and reinforcing steel to be assembled within the excavation before the GRP tank was installed and the concrete poured.
LCM maintenance manager David Scott said: “We brought the idea of using a Kijlstra precast concrete tank to Biffa as a more efficient alternative. We already knew some of the people working at Kijlstra, although we’d never used their products before. We looked at the precast option and quickly realised this was a much better alternative for this project.”
The Kijlstra tank, from the company’s Vario range, is a simple cube measuring 3m x 3m x 3m with openings for pipework and a level sensor to indicate when the tank needs emptying.
The one potential disadvantage, compared with the GRP tank, was that a mobile crane was required to lift the concrete tank, which was installed in one piece. “But the crane was only on site for four hours, so it was hardly expensive,” says David.
LCM having dug the excavation and levelled the bottom with sand, it was then just a simple matter of trucking the tank in and lifting it into position. “The tank was in position within an hour of it arriving on site,” says Steve. “And they were already back-filling the excavation by the time I left the site.”
LCM’s David Scott says the excavation was dug, the tank installed and the hole back-filled all within 36 hours. Had a plastic tank been installed, the task of assembling formwork and reinforcement, plus the time taken for the concrete to cure, would have resulted in the excavation remaining open for several days – or even weeks.
“Basically it saved us about four weeks,” says David. “It was late November and at that time of year you don’t want to leave an excavation open a minute longer than you need to.”
The rapid installation of the tank impressed both LCM and Biffa, with the result that David Scott is hopeful of repeating the exercise for the same client on other sites. “We’re already talking to them about two more jobs, and there could be more after that, too,” he says.