“The two polygon areas are defined by the Applicant as areas that avoid known hazard zone of faults, boreholes and wet rock head and the mining hazards of solution brinewells and dry mining. This is the essential conundrum: these two areas do indeed avoid all known constraints, but are also areas where there is little hard geological data. 16. The Secretary of State notes the Examining Authority’s view in ER 5.64 that ‘The availability of geological data is nonetheless an improvement on that presented in the last planning application in 2009... ‘ However, the Examining Authority are also of the view in ER 5.65 that “the relatively small amount of additional geological data” consists largely of reinterpretation of geological information and, as indicated above, the geological analysis submitted as part of the application falls short of that required by NPS EN-4. Although the Secretary of State agrees the current application must be considered on its own merits, he also notes the Examining Authority’s view in ER 5.66 that ‘the technical assessor for the 2007 Public Inquiry recommended that at least two more seismic lines be undertaken and drilling and geophysical logging of boreholes on these lines to prove ground truth. In view of this and the subsequent failed planning application in January 2010, we are surprised that no seismic surveys were undertaken across the polygon areas to support this application...”. 17. The Examining Authority’s overall conclusion on the case for Development and recommendation that the Order be granted is therefore based on the proviso, that Halite “can demonstrate that the suitability of the salt in the two polygon areas is as high as it is assumed for the purposes of the application” (ER 7.27) and that development consent is made subject to “a major proviso concerning the procurement of more detailed geological data to confirm the ability of the two polygons to store substantial volumes of gas (ER 7.28). 18. The Examining Authority therefore sought to address the issue of geological uncertainty of the proposed storage areas by recommending inclusion in the draft Order of a requirement (on which commencement of the Development would be conditional) for Halite to carry out more comprehensive geological surveys post-approval (see ER 9.36 and draft Requirement 6(1) and (2) of Schedule 9 to the draft Order at Appendix D to the ER). The requirement would also make commencement of the Development conditional on the working capacity being shown by the assessment to be greater than “300 million standard cubic metres at the standard temperature and pressure” (which is half the working capacity envisaged by Halite).The Secretary of State notes that the Examining Authority considers that including such a condition “would meet the detailed assessment required under NPS EN-4 to confirm that the sites selected (i.e. the two polygons) are suitable, which in our view means they have sufficient thickness of un-faulted suitable halite to contain the proposed volumes of gas to be stored.” (ER 9.24). 19. The Secretary of State does not however consider this approach to sufficiently satisfy the policy to be applied under EN-4 on which he places considerable weight. The requirement in Part 2.8.9 of EN-4 provides for example that “Applicants should undertake and supply to the IPC [i.e. the Infrastructure Planning Commission; now the Planning Inspectorate acting on behalf of the Secretary of State], a detailed geological assessment to demonstrate the suitability of the geology at the site for the type of underground gas storage proposed.”
“When considering storage in a salt cavity, the geological assessment should include depth below surface, salt thickness, salt purity and presence of shale bands which could affect cavern design. In addition, a study of the geological integrity of the overlying strata and potential for collapse, taking account of the proposed minimum and maximum working pressures, will need to be undertaken. The assessment should include the construction, operational and decommissioning phases and should cover the long term integrity of the affected strata after decommissioning or closure of the storage facility. The IPC will consider the geological assessment alongside the environmental assessment if the former does not form part of the [Environmental Statement]” 20. The Secretary of State is satisfied that, as stated in section 4.11 of NPS EN-I, an underground gas storage site would be subject to stringent safety standards covering the life cycle of a facility from design and build through to decommissioning under theControl of Major Accident Hazards (COMAH) Regulations 1999 and enforced by the Health and Safety Executive and Environment Agency jointly. However, in the absence of a pre application geological assessment as required by NPS EN-4, the suitability of the proposed underground gas storage project cannot be properly considered by the SoS - and may have also gone some way to contributing to local fears and opposition to the project.”