Located next to the bay in the coastal town of Swansea, South Wales, the former gasworks site in Oystermouth Road has a history of gas production dating back to the nineteenth century.
The Swansea Gas Light Company began producing gas on the six-acre site in 1841. As demand increased, the works were extended over the years until there was no further room for expansion on the site and at this point new works were set-up in Morriston, an industrial area north of Swansea.
Gas production at Oystermouth Road finally ceased in 1922 and, although the site was later used as an operations centre, much of the remaining plant and equipment was dismantled and scrapped.
At its peak, the site housed four holders which stored and distributed gas from the site. One of these was later dismantled in 1932 while the remaining three were used until 1949 as part of the gas distribution system for the town.
An initial site investigation, including desktop studies and fieldwork tests, was undertaken to identify any areas of contamination and obstructions present below ground. Exploration boreholes were sunk up to a depth of 14.7 m and mechanically excavated trial pits were carried out to provide a more detailed view of any contamination and to locate buried foundations. Samples were taken for subsequent chemical analysis to enable a remediation strategy to be designed. The remediation programme, managed by National Grid Property, was designed by Waterman Environmental in consultation with local authorities, the Environment Agency and the Health and Safety Executive to produce a programme that would ensure the successful regeneration of the site. The works were carried out by VHE Construction over a five month period.
However, before the remediation process could begin, National Grid, the company responsible for the pipeline infrastructure, had to relocate the main gas supply to a new pressure reduction station constructed on the site.
The first phase of the remediation programme saw the decommissioning of the three remaining gasholders, the largest of which was 40 m in diameter. Each was approximately 20 m in height and entrenched 7 m underground. After taking the water out of the holder wells, a seven man team cut the holders into sections and carefully removed them by crane from the supporting concrete bases. The removal of tar wells and other buried structures followed, with all contaminated materials removed from site to licensed tips for safe disposal. The excavated areas were then backfilled with clean material, including the concrete which had been broken-up and crushed from the remaining areas of hard standing on the site. The final stage of remediation was to remove a 0.75 to 1.0m strip of soil from the majority of the site and replace it with a layer of engineered granule material.
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to the site
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