GEOSYNTHETICS manufacturer MMG Civil Engineering Systems has supplied a range of materials for a drainage rill at the new Lowestoft Waste Water Treatment Centre in Corton, Suffolk.
The rill, which will deal with the potential stormwater surge from the domed roof of the centre, is made up of a 'sandwich of geotextiles' explained MMG area manager Jonathan Sturt.
'This will ensure the integrity of the rill through a wide range of ground conditions and the stormwater velocities expected to fall from the centre's roof, ' he said.
Anglian Water's £70M facility is being built by main contractor John Mowlem. It is due to come on line in January and is expected to improve the treatment of sewage discharged from Lowestoft and the surrounding areas.
Treatment plants capable of processing more than 6000 litres of wastewater per second are contained beneath a 14,000m 2oval dome, 160m long and 100m across.
Stormwater surge from the centre's roof is estimated to be as much as 100 l/s. The 4m wide rill runs around the building and will discharge run-off into storage lagoons.
A needle-punched non-woven geotextile protector was laid on to the profiled soil. This was followed by a Nicotarp impermeable geomembrane, again protected from above with a layer of needlepunched geotextile. The sandwich is topped off with a layer of MMG's Armorloc concrete revetment blocks.
'Since a weir has been incorporated to control the water flow, MMG's Deckdrain drainage geocomposite was laid below the Armorloc to prevent puddling occurring on the top of the blocks, ' said Sturt.
For aesthetic and environmental reasons, much of the external pipework and structure of the treatment plant has been kept below eye level, with excavations contained within 3m high MMG Porcupine steep retaining walls. Earth behind the Porcupine blocks has been reinforced with Fortrac geogrid.