Stormwater management solution provider SDS has won a contract to provide an attenuation system for the new Twickenham Academy, a college specialising in sports and digital technology in England.
The building is due for completion in Easter 2013 and will be three stories high, with some 90 classrooms, and will be split into three colleges, Holmes, Wembley and Upper College.
Due to the area of catchment, an attenuation tank has been installed to hold stormwater in times of heavy rain and release it via a vortex flow control into the main storm system.
SDS supplied and installed the attenuation tank using its GEOlight units, with a storage capacity of 200m3. The provided system consists of two manholes (inspection chambers) connected by a length of perforated distribution pipe which feeds the storm water storage reservoirs on either side formed from GEOlight. This is post-consumer PVC waste diverted from landfill.
The distribution pipe is normally from 225mm up to 500mm diameter, generally covered in a trench filled with draining material such as 15/25 clean graded stone, free from fines.
The reservoirs and distribution pipe are wrapped in a waterproof membrane, such as butyl, to prevent water seeping into the surrounding ground.
The top of each reservoir has a vent which is connected back to the upstream manhole. A geotextile or 10mm mesh geogrid is laid between the distribution pipe and GEOlight to prevent the units being clogged by the draining materials.