We worked for Southern Gas Networks (SGN) on the gas works site in the West Sussex town of Crawley.

This project involved the decommissioning (desludging and dewatering) and demolition of Gasholder No.1, a 3-lift spiral gasholder. The works included the dismantling of the gasholder and associated plant, along with other additional structures occupying the site and the infilling of all pits to leave an overall clear and level site.

The only entrance to this project was through the busy main road of A2011, which created significant traffic management problems, especially with the construction site nearby that restricted access even further. The site was also surrounded by numerous environmental constraints: the nearby flowing Gatwick Stream, is close to the Ballast Hole fishing pond, and many trees that we needed to protect during the works.

The vessel, measured approximately 50 metres in diameter, was constructed of steel which varied in thickness at each of the inner layers and due to its size and the thickness of the metal, the structure was cut up mechanically using hydraulic shears.

Site overview video:

We were appointed as the CDM Advisor for the project. Our roles included checking the Principal Contractor’s Construction Phase Plan (CPP) and reviewing the Risk Assessment and Method Statement (RAMS) for the project before issuing the Authorisation to commence construction activities.

Throughout the project’s period, we carried out audits which were planned to coincide with the specific phases of the project. Such audits included the CDM compliance audit, a specific environmental audit to ensure the sludge and waste were removed in line with the Environmental Agency’s requirements, and a process-specific demolition audit.

• Review and comment on the Construction Phase Plan and issue a report.
• Review and comment on the Risk Assessments and Method Statement and issue a report.
• Carry out the pre-start CDM site audit and issue a report.
• Carry out the environmental site audit and issue a report.
• Carry out the demolition process site audit and issue a report.