Due to be completed in the Summer of 2012, the rebuild of the Darwen Vale High School and Engineering College in Blackburn is now well underway. When finished, the 8000m² campus building will provide for a 1200 place community school, housed in a new, environmentally sensitive building.
Already complete and opened in January 2011, the new sports arena can be used by the public, both outside and during school hours. It includes a fitness suite, fully equipped sports halls, upgraded pitches and courts.
The arena has been provided with a 400m² car park drained with the first UK installation of Hauraton DRAINFIX® CLEAN filter-bed channel system. These drainage channels directly cleansed rainwater runoff from the car park into a controlled water course which is part of the areas’ SUDS scheme.
Legislation now demands surface water runoff from hard surfaces is managed to mitigate local flooding. It also requires rainwater running off car parks, yards, trading estates and highways be cleansed of pollutants before it enters a controlled water course or seeps into ground strata.
In these applications the Sustainable Urban Drainage System (SUDS) usually has a separator tank, retention or filter system integrated into the scheme. SUDS can take many forms including, manufactured permeable block paving, underground percolation blocks and more natural installations such as ponds, detention basins, controlled water course, wetlands or reed bed.
The DRAINFIX® CLEAN channel run was assembled on site from the following components:
- Channel run made up of one metre long, 300mm (usable) width x 505mm (usable) height fibre reinforced concrete channels. Each channel having a maximum retention volume of 70 litres/m. 400mm width channels are also available, with a retention volume of 110 litres/m.
- 100mm Diameter mesh drain pipe made of highly durable PE-HD and covered with a geotextile tube. Supplied in 1 metre lengths with push fit socket for connection on site.
- Carbonate substrate granules to create filter-bed, supplied in bags to site.
- Ductile iron bolted down gratings with a load category of D400. Supplied palletised. Gratings with a loading category of E600 and F900 are also available. Please note, the Hauraton SIDE-LOCK® patented boltless system can be specified on other projects. SIDE-LOCK® allows gratings to be installed and later removed quickly. Once a grating is positioned over the channel, foot pressure is simply applied. A loud click is then heard which confirms it is securely locked onto the channel. The grating is removed using a large screwdriver inserted into a discreet leverage point.
How DRAINFIX® CLEAN works.
The DRAINFIX® CLEAN filter-bed channel system was developed in collaboration with a number of European Universities and subsequently tested under severe, real life conditions over many years.
Extensive testing showed pollutants, such as heavy metals and hydrocarbons, contaminating a hard road surface naturally attached themselves to very fine particles. When it rains, these particles are washed into the drainage system. Field tests found very little of this polluted material was removed by separators or retention systems; the DRAINFIX® CLEAN channels’ incorporating a filter-bed was the only system to work effectively over a long period. In a relatively short time, the particles and organic matter from the surrounding drained surface penetrate the filter-bed and begin to form a filter cake. As the filter medium continues to mature, micro-organisms and small creatures invade and start a soil forming process, this absorbs and breaks down the captured pollutants.
The channels are sized for this stage of the cycle, providing sufficient water retention volume to ensure there is no back-pressure or overflow of the system.
Matt Denniff, Hauraton’s Project Manager, provided support for all the engineers and contractors involved with the sports arena car park drainage scheme ensuring the DRAINFIX® CLEAN system fully integrated with the local SUDS scheme. Although the 38 metres of DRAINFIX® CLEAN channels installed were larger than would have normally been used, the overall component and installation cost was about the same when compared with smaller, standard channels with a separator tank or retention system.