Hampstead developers criticised for digging basement extensions on the cheap

Dr Michael de Freitas

Dr Michael de Freitas - Credit: Archant

The thorny issue of basement excavations is one that simply will not go away in Hampstead, with fresh controversies unearthed nearly every week.

Last week it was Labour peer Lord Parry Mitchell suing his neighbour for burrowing under his land, while tonight an application for a multi-storey basement in Maresfield Gardens goes before Camden Council’s development control committee.

As the committee ponders this latest application at the town hall, an expert on the geological impact of basement excavations will be sharing some of his knowledge with the people of Hampstead.

Dr Michael de Freitas, emeritus reader of engineering geology at Imperial College London, is tonight due to deliver a talk titled Basement Excavation in Camden: Its Relationship to Geology and Groundwater at St Stephen’s Church, in Rosslyn Hill.

The Ham&High asked Dr de Freitas to outline some of the themes he is set to cover.

“The most important thing to do is to remember that we did not make the ground,” he said. “Everything above ground level is man-made – we make bricks, cement, concrete and we can test all this. But we did not make the ground and that means we need to put more effort into understanding it than most people appreciate.”

Dr de Freitas explains the earth in Hampstead is “not as simple as most proposals suggest”, with an upper layer of gravel, sand and clay, which makes predicting the movement of water and the ground’s “response” to excavations extremely difficult.

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He said: “Engineering is perfectly capable of creating basements that do not cause problems to neighbours, but this requires advanced knowledge of the ground based on good facts, sophisticated design and meticulous supervision. That is expensive.

“The biggest problem is that developers want high-grade engineering, which requires very sophisticated techniques, without spending the money.

“They want champagne engineering on beer money. You can do it, but you will have problems.

“The damage to neighbouring properties is often a price the neighbours pay for owners not investing sufficiently.”

His talk is a timely one as Camden Council is currently consulting on amendments to its planning guidance.

The key suggestion is that the council will demand an independent assessment that is funded by the applicant in some cases, where there is a dispute over what the impact will be.

Dr de Freitas welcomed this, and also issued a call for decision makers at the council to receive training to help them judge tricky planning applications.

The Heath and Hampstead Society, which organised tonight’s talk, backed the suggestion. “This area is so technical,” said Tony Hillier, the society’s chairman.

“Councillors and officers should have more training in understanding what’s going on.”

Tickets to the talk are £10 on the door and it begins at 7.30pm.