Rejection justified by gas storage doubts

The secretary of state has refused to grant planning permission for the creation of a natural gas storage facility in former salt mines in Lancashire after finding that the appellants had failed to assess the risk of subsidence adequately.

The 261ha site mostly comprised low-lying open agricultural land and saltmarsh in the Morecambe Bay special protection area and adjacent to the Wyre Estuary site of special scientific interest. The area had a history of brine working, where salt solution had been used in chlorine production until 1994. This had created depressions in the land where underground mines had collapsed.

The appellants proposed to create up to 24 caverns by pumping seawater into the ground to dissolve 49.5 million tonnes of salt deposits. The solution would then be pumped back into the Irish Sea. The scheme would involve two dozen wellheads connected by underground gas distribution pipelines to a gas compressor station.

The appellants explained that up to 1.2 million tonnes of natural gas would eventually be stored in the caverns. They maintained that the scheme would provide important energy infrastructure, given the national need for more gas storage. This was necessary in order to avoid running out of gas supplies during very cold winters, they argued.

While acknowledging the national need for more gas storage facilities, the inspector also noted the considerable uncertainty associated with operating a facility of the size and nature proposed. In particular, he concluded that the information provided by the appellants on the geology of the area and the hydrological impact of the proposal was insufficient to enable permission to be granted.

The appellants had carried out a detailed desktop assessment but failed to drill any deep boreholes to provide a three-dimensional picture of the local geology, he noted. Without such information it was impossible to conclude that the gas storage capacity would be as large as the appellants suggested, he held. It might not even achieve 20 per cent of the total predicted, he found.

The inspector also voiced concern over progressive or sudden subsidence of the pipes. The risk assessment had not considered this as a possibility even though it could lead to subsidence at the surface, he noted. The risk would be even greater if one of the caverns collapsed and created a crater at the surface, he added, since it would be incapable of being corrected. In the absence of a detailed assessment of the risks of gas migration and the potential for explosion, he decided that the site was unsuitable for underground gas storage.

DCS Number 100-050-836

Inspector Edward Simpson; Inquiry.

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