Articles & Case Studies


Posted: Friday 17th July 2015

Storm water management specialists Hewitech UK has recently supplied its products for a brand new fire and rescue station at Tolvaddon for the Cornwall Fire & Rescue Service.

The project, which is nearing completion, is on a 2.15 hectares greenfield site and comprises the development of two new buildings where various existing facilities in the county will be amalgamated. Servicing the Camborne and Redruth areas, the site will be shared with Service Headquarters which will provide critical services such as fire control, training, vehicle and equipment maintenance, as well as being the Services’ administrative centre. The new project replaces the existing community fire stations that are over fifty years’ old and provides improved services to reach 13,900 more residents in Cornwall within a ten minute response time.

Although the site is on a 1 in 7 incline, there was the usual need to ensure correct run-off during storm conditions as well as water storage facilities in such events. Consulting engineers Jenkins & Potter used computer modelling to design the system to allow for the run-off from a 1 in 30 year return storm and to meet the requirement for the run-off produced by a 1 in 100 year(1%AEP) return storm including an allowance for climate change to be contained on the site and then be discharged at equivalent greenfield rates which were agreed with the Environment Agency via a Flood Risk Assessment. This led, due to the confined sloping site, to the requirement for additional storm water storage below the surface of the training yard. A swale or open ditch along the bottom of the site leads water through two pipes into and out of the underground storage provided by Hewitech’s attenuation tanks. The swale discharges to the adjacent Red River via a two stage flow control device.

The footprint on site was restricted as it was necessary to install an attenuation tank shoehorned in between two gas mains. As well as the value and performance presented by the Hewitech Variobox, the system was chosen as it could be made in different sizes and in smaller increments for the exact area needed to be covered.

For the project, Hewitech provided 227.45 cubic metres of its Variobox Traffic as a ‘dog-leg’ attenuation tank, with two Controlbox access channels. The Variobox Traffic is 600mm deep and very strong at 400kN per square metre. The access and maintenance channels provided are 500mm in diameter. All controlled discharge is into the adjacent river, which is only 8 metres away.

Commenting on the success of the scheme Stuart Denslow, project manager at Kier Construction commented, “We found Hewitech very easy to work with, all materials arrived on time and the whole process went very smoothly, with no problems. We are very happy with the result.”

Hewitech’s storm water management systems are the strongest on the market and all are tested to RAL standards which are more stringent than those in the UK. Its Variobox system is a modular cellular storage system of polypropylene and PVC cellular fills with a built-in maintenance access tunnel. The complementary Controlbox features a 500mm opening for optimum storm water control. All Hewitech systems are installed by the company’s own team to ensure quality control and warranty.

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