Project Team: Taylor Woodrow Construction, Cardiff County Council, ICE Design & Construct.
Taylor Woodrow co-ordinated the detailed design for the remediation, which was undertaken by Churngold Remediation and Arup. Keller Ground Engineering designed the ground improvement works and the gas & leachate barrier and Tony Gee & Partners designed the revetment system.
The site is located on a man-made peninsular within the fresh-water lake formed by the construction of the Cardiff Bay Barrage. Construction of the barrage began in 1994 and freshwater impoundment commenced in 2001. Cardiff Bay represents an area of major regeneration in Cardiff, and is protected by the Cardiff Bay Barrage Act, which sets standards for water quality.
The site had a history of industrial and commercial land use including the presence of both licensed and unlicensed landfill tips. Coal discharging operations and large-scale storage of diesel fuels had resulted in contamination of the site by heavy metals and hydrocarbons.
The main works undertaken on the site included:
- Exsitu bioremediation of 28,000m3 of hydrocarbon contaminated soil
- Insitu bioremediation of 17,000m3 soil & groundwater
- Removal of hydrocarbon free product from groundwater
- Major earthworks to relocate 300,000m3 of treated soils in line with end uses
- Treatment and validation of 14,000m3 of Japanese Knotweed infested soils
- Installation of a bentonite cut off wall with gas membrane and leachate drainage system to the perimeter of the landfill tip
- Dynamic & vibro-compaction of 95,000m2 of disused landfill tip
- Installation of a passive gas venting system to the landfill tip
- Installation of 1600m of sheet pile revetment including anchor system at the water’s edge
- Improvement of soft alluvium by use of band drains and surcharging
Breaking out of hardstandings and the crushing, screening and reuse of arisings on site
- Use of 50,000m3 of recycled aggregate
Works on site began in September 2003, and the project value was approximately £15 million.
The technologies used on site included cutting edge insitu bioremediation techniques utilizing electrolysis to treat ground water contamination. The project was one of the largest bioremediation operations undertaken in the UK and all hydrocarbon-contaminated soils were reused on site.