Sink holes - a wider problem?

[whole diary]

[eightonedee]

Personally, I'd be looking to sue my property surveyor / conveyancer for not identifying those issues, if they weren't.  Shocked

Unfortunately these problems lie outside the "usual" residential searches (other than in mining areas or brine subsidence areas where specific additional searches are commonly undertaken), and unless there are visible subsidence cracks or similar, this would be outside a building condition survey.

When I was in practice acting for developers, I'd do an enhanced environmental search which would in broad terms indicate if the local geology indicated a risk of subsidence, and any competent developer should undertake geotechnical surveys. The problem insofar as I am aware is that in areas with soluble substrata these sinkholes can develop rapidly if (for example) there's a leak from an underground water main.

[Chris from Nailsea]

Here in Nailsea, we are very much within the historic mining area of the North Somerset coalfield.  We moved house, just over a year ago, and our building surveys were commendably detailed.

When we moved into our previous house in Nailsea, some 25 years ago, the searches were similarly detailed: they named an historic mine shaft (the nearest to our property) and were able to give its location to within a very few feet.

We have never had any problems with subsidence or sink holes: more of an issue was the bluddy huge willow tree, with its roots soaking up water from most of the back garden, causing some slight settlement of the brickwork. 

[Fourbee]

Another one - rather scary.  From the BBC^» (British Broadcasting Corporation - home page):

(Article continues)

The cause of the sinkhole remains unclear, but experts at the British Geological Survey (BGS) say it could be caused by a burst water main.

When new properties are added (as it seems in the Godstone case) water companies can increase the pressure in the main which leads to burst pipes; something else to add to their ongoing charge sheet if that is the case.

[johnneyw]

Our next door neighbour was recently in conversation with a old local who recalled playing as a child in the area that our row of 3 houses was built on in the 1960s.  It was a small old quarry but abandoned many years before.  The recollection was that there was some kind of small well in the corner where my neighbours house now stands.  They weren't aware of it from any surveys though and off course, in a child's imagination, a modest pit in an old quarry site could be transformed into a well.
There's certainly been no sign of any subsidence or any further indication of it despite extensive excavation work carried out around the property over the years.... but the comment certainly caught their attention!

[ChrisB]

The area in question was an old sand quarry - so likely a burst pipe (confirmed by SES Water) washing away sand(stone) quite quickly.

I feel for the owner of the house immediately to the left of the hole in that photo above. Its only ben built three years...