1BZ DRAINAGE GEOCOMPOSITE – Drainage to the rear of a retaining wall (Carluke)

The 0.8 hectare Park & Ride facility is situated on the west side of Carluke Station and due to the elevated position of the station in relation to the park & ride area, it was necessary to build appropriate pedestrian links, including a DDA compliant pedestrian access ramp. A key element of the design was the provision of an engineered drainage system behind the retaining walls.

For Carluke’s Park & Ride facility, South Lanarkshire Council specified TERRAM 1BZ Drainage Geocomposite which has a geotextile filter bonded to one side of a geonet core and an membrane bonded to the other side – a cut-off drain. These composite drains are frequently used to replace traditional granular layers as they are much easier to install, particularly on vertical faces, have a proven record of performance, and avoid the need to use primary aggregates.

At Carluke, TERRAM 1BZ was fixed to the access ramp’s retaining structure prior to the introduction of the backfill material. The TERRAM 1BZ was positioned so that it would act as a vertical channel, directing excess groundwater into a perforated drainage pipe at the base of the walls which would be carried to the nearest main drainage system.