Geohazards - could these effect future possiblity of extension

[SALL2009]

The land / environment searches for a property we are purchasing has passed, but points to these considerations. Compressible Ground and Running Sand. The last bit says, "Certain constraints may apply to land uses involving excavation", could this mean issues when it comes to digging foundations, if we want an extension in future?


3.04 Geohazards | Compressible Ground PASS (WITH CONSIDERATIONS)
The British Geological Survey indicates that the property is within 50 metres of an area where there is significant potential for compressibility problems.

CONSIDERATIONS: Do not drain, load or de-water ground near the property without technical advice. There is a possible increase in insurance risk from compressibility due to drought or dewatering unless appropriate foundations are present. There is significant potential for compressibility which might cause subsidence damage when loaded by a building or structure, or
when the groundwater changes. Prior to structural changes and any draining or dewatering of the ground near the property a chartered surveyor will need to be
consulted.

3.05 Geohazards | Running Sand PASS (WITH CONSIDERATIONS)

The British Geological Survey indicates that the property is within 50 metres of an area where there is the possibility for sand to

be fluidised by water and ‘run’, with the potential to remove support from overlying buildings and cause subsidence damage.

CONSIDERATIONS: Normal maintenance to avoid leakage of water-bearing services or water bodies (ponds, swimming pools)


should prevent any problems related to running sands.

Certain constraints may apply to land uses involving excavation or the addition or removal of water.

 

[^woody^]

Rafts, piles ...... or strips. You wont know unless you get the actual garden checked, and this will be more accurate than "within 50m".

There is lots of this running sand all around Birmingham. Lots of houses built on it too.

 

[Ian H]

I’ve seen lots of running sand too, doesn’t seem to affect houses but makes it hard to repair drains.

 

[noseall]

We built an extension (Great Bridgeford, Staffs) in what could only be described as old riverbed mebbe? It was a friable collection of tiny gritty stones, similar to screed sand (grit sand/sharp sand) but at least it was dry. Nightmare to try and achieve neat trenches as it kept on collapsing in. BC thought it was ok and typical of the area. Standard strip too.

We experimented to see the effects of digging along side a wall that needed demolishing in any case. We dug along side the wall until it collapsed due to the egg timer sand falling away as we dug along side. There would be no running away, put it that way!