Attenuation Tank, Stowupland
The lining of a typical small attenuation tank on a new housing site.
The tank was 6m x 5.5m x 1.2m providing a gross volume of 39.6 cubic metres. The attenuation blocks were all the same size at 1m x 0.5m x 0.4m high and were oriented 6 blocks x 11 blocks x 3 blocks high, ie 198 blocks @ 0.20 cubic metres each = 39.60 cubic metres.
6m x 5.5m x 1.2m
Our company approached the project by factory prefabricating a 1.00mm polypropylene liner into a five-sided open-topped 'box' format. There was also a 300g per square metre geotextile fabric which was factory prefabricated on the same basis.
The materials were taken to site and the installation sequence was as follows:
- Placement of the geotextile layer.
- Installation of the prefabricated 1.00mm liner
- Placement of the 198 blocks.
- Sealing the liner to pipe inflow/outflow stub end penetrations. Sealing of the vent.
- Placing of the prefabricated lid liner across the top of the tank and its extrusion welding to the previously installed liner. This created a fully welded liner to encase all six sides of the tank area.
- Completion of the installation of the remaining geotextile overlay to the outside of the tank.
Our time on site was 1 day for the whole of the work detailed above. The Contractor on-site then joined the pipework runs to the sealed stub ends as left by our company. The area was then backfilled and the project completed.
End Client: Orwell Housing Association
Materials Used: Exceliner PP 1.00mm (polypropylene) / 3600N geotextile
Grounds Works Contractor: D A B Associates
Civil Engineering Merchant: Collier & Catchpole Ltd