Environmental Impact Assessments for North Sea gas reserves

Premier Oil E&P UK Ltd is seeking to exploit the gas reserves in Tolmount field in the southern North Sea. The company intends to install a pipeline to carry the raw product from the field to the onshore gas processing facility at the terminal in Dimlington, East Riding of Yorkshire, UK. Xodus coordinated the off- and onshore environmental assessments and RSK undertook the geology, hydrology, flooding and contaminated land assessments for inclusion in the environmental statement.

RSK assessed the geology, ground conditions and hydrology for the environmental statement. The onshore environmental statement covered all the work above the mean low-water spring tide mark, including the landfall and beach crossing, the installation of the gas pipeline through a cliff section and the groundwork from above the cliff into the existing gas terminal.
A Phase 1 contaminated land assessment was requested by the council because part of the groundwork was within the existing gas terminal boundary on brownfield land and there was concern that the contractors might encounter contaminated land during excavation work. The conclusion was that risk was limited.
The flood risk assessment concluded that site drainage could all be managed within the existing drainage network and that there would be no increased flood risk downstream of the development. Control measures were established for construction work across the beach section to minimise the risk to construction staff and plant.

The cliff section is in a site of special scientific interest for geological reasons, so required conservation from damage resulting from pipeline installation. The developer proposed emplacing the pipeline through a tunnel and shaft arrangement such that the development would not affect the natural erosion of the cliff. RSK needed to work closely with the coastal processes specialist to ensure consistency of assessment in both sections and the provision of appropriate information to the regulators.
Measures to control the potential impacts to the ground and water environments during the construction, operation and decommissioning phases of work included importing ready-mix concrete to avoid batching concrete on-site; using dry drilling and auger techniques to avoid using drilling mud; and having good material handling procedures to minimise the pollution risks from site activities.