Basement excavations: Society's challenge to decision-makers

The Heath & Hampstead Society welcomes the fact that Camden Council has begun a constructive geotechnical and planning law dialogue with us at senior officer and executive councillor levels, to ascertain the correct way to assess the legality of individual basement applications in NW London, and in turn to advise the development committee hearings what is the proper legal and technical framework within which to determine such applications.

However, serious neighbouring property damage has already been found next door to basement excavations approved in recent months by Camden, and is expected on good authority to harm properties beside some huge excavations more recently approved, but not yet dug, as well as some where the application process is not yet complete.

We therefore urge Camden to accelerate their side of the dialogue and answer for starters the two following questions. Our sense of urgency has been heightened by the fiasco of last Thursday's hearing on 94 South Hill Park. We are at the same time extremely grateful that a clear understanding of their legal duties enabled the committee to ignore the obvious legal and technical misdirections from the officers, and so reject a life threatening basement from being dug.

The following questions need to be answered without further delay. We have taken good advice in arriving at our position. Camden clearly has not yet accepted our approach. On behalf of the community the Society wishes to know in writing whether Camden has good reasons for agreeing or disagreeing with us.

1. The Geology: all recent geotechnical site tests on the public record have shown that this is an area prone to instability when deeply excavated. Authoritative geological scholarship opines that local geotechnical characteristics cannot be reliably ascertained for damage assessment purposes by desk top studies using the British Geological Survey alone.

On what authority does Camden deny that these facts are the proper planning law starting point to assess applications? Apparently preferring instead to leave matters post planning consent to structural analysis (which is not concerned with damage to neighbours), toothless building regulation and party wall legislation (which cannot prevent serious damage from occurring).

2. Planning Law: The legally and geologically defined types and potential causes of neighbour property instability clearly make PPG 14 the proper basis on which to require the developer to commission correctly-sited, multiple properly logged underground soil tests to a depth well beyond the proposed excavation. Based on these, it is Camden officers' duty, as part of the planning process, to require the developer to report to them the minimum likely damage to the neighbouring property using the best construction and damage limitation methods within an achievable time frame (some damage is inevitable).

It is then the development control committee's duty to consider any counter assessment put by the neighbour and decide whether the predicted level of damage is acceptable and satisfactory. If it is not, the application must be refused.

On what authority does Camden assert that PPG 14 only applies in disused mining areas and that Camden cannot therefore apply PPG's decision-making directions here? The opinion that it is relevant to local planning applications is supported by the following documents which are in Camden's hands and on the public record: a formal opinion by David Holgate QC, a summary of that opinion by Lord Hoffmann, and a 15-page analysis, ironically enough from a leading developer who is defending his application, having gone through the full process described above and who has submittted 300 pages of technical analysis from a leading firm of consultants to Camden based on the PPG 14 process.

It is not good enough for Camden to attempt to duck these responsibilities with a last minute perfunctory email exchange with the environment agency.

Tony Hillier

Chairman, Heath & Hampstead Society