Contaminated Land Capping

Brownfield Drainage, Pozidrain - Honda Car Park, Avonmouth, UK

Client Honda
Contractor

GSE Group

Consultant Aspinwall
Product

Pozidrain

Quantity

72,000m²

Benefits

– Drainage & capping membrane
– High flow capacity
– Double textile for adequate reinforcement & separation
– Rapid installation
– Replaced 10,800m³ drainage stone

Project Description

The Honda Factory Car Park site is located on land bordering the mouth of the River Avon, near Bristol. This part of Avonmouth is one of the most contaminated sites in south-west England. It has a long industrial history as a munitions and mustard gas plant in 1917, zinc, lead and sulphuric acid production until 1972 and production of agrochemicals and pharmaceuticals until 2008, when the site was closed. Site investigations undertaken during the planning application process for redevelopment of the site detected numerous contaminants.

The Challenge

The requirement was to minimise the use of costly type 1 stone material and design a capping solution that would enable fast installation on this large area. The traditional geosynthetic capping system comprising protection textiles, impermeable membrane and drainage stone was considered outdated and costly.

A cost saving, innovative design was required to enable economic redevelopment of the contaminated site. A key aim of the development strategy was to minimise off-site disposal and enable the contaminated materials to remain on site.

Site investigation reports established a significant risk of ground water pollution if rainfall and surface water were allowed to percolate into the contaminated sub-formation. An effective capping and drainage membrane was required in order to enable this contamination to remain on site and avoid the significant costs associated with a dig and dump option.

The developer approached Aspinwall consultancy to design a cost effective contaminated land remediation solution for this environmentally sensitive location.

The Solution

The designer worked with ABG to develop a cost effective geosynthetic capping solution. Aspinwall carried out the design using the Pozidrain 6S250D/NW8 drainage geocomposite to provide combined drainage, separation, capillary break, reinforcement and capping all in one geocomposite layer. Pozidrain is permeable on one side only, with the other side of the cuspated drainage core being flat and impermeable to act as a capping membrane.

The tensile strength of the geocomposite layer was used to provide reinforcement and enable the sub-base thickness to be reduced from 300mm to 150mm, reducing the volume of the required stone layer by 10,800m³. Pozidrain geocomposite was installed on top of the contaminated sub-formation and covered with 150mm of type 1 material and a permeable asphalt overlay.

Proven chemical resistance in landfill applications ensured Pozidrain was suitable for this contaminated land site. The design and installation was approved by the Environment Agency.

ABG Pozidrain

The ABG Service

ABG provided technical advice and design assistance on this project. This included supervision during the installation and liaison with the Environment Agency.

Contact ABG today to discuss your project specific requirements and discover how ABG past experience and innovative products can help.

Additional information