Subsidence doesn’t just occur in coal mining areas; significant problems exist in London and the south-east and in other non coal mining areas.
The home buying public need to avoid the misery of subsidence damage. They need to be aware of the risk of subsidence from man-made causes like coal mining and from natural causes like clay shrinkage and soluble rocks. Ground stability is as relevant as flooding or contaminated land to a home-buyer, and to their lenders and insurers.
This report provides essential information for those customers considering property purchases and provides property specific information in a simple language on the potential hazards relating to natural subsidence throughout Great Britain, the impact of mining within the coalfields and the risks and occurrence of damage caused by brine extraction.
The British Geological Survey (BGS) provide unique information about natural ground stability within a 50 metre radius of the property. The information in the ground stability report is derived from a variety of sources including detailed digital geological mapping, recorded incidents and, most importantly, input from experienced geologists.
Ground movement occurs naturally and depends on the nature and composition of the underlying geology. The BGS has identified 6 natural hazards, which may cause ground movement.
Shrink-swell clays – Clay rich soils will shrink and swell with seasonal weather changes causing ground movement. Movement may also occur from both the planting and removal of trees or leaks from water pipes or drains.
Landslides – These occur in certain conditions and depend on the geology, angle of slope, drainage, rainfall and a change in the drainage pattern.
Soluble rocks – In certain parts of the country some rocks can dissolve from moving water giving rise to cavities and subsidence. This is most likely in areas where gypsum or salt occur but can be a potential hazard in areas of limestone and chalk.
Compressible and collapsible ground – Information is given on areas prone to compression or collapse when a load is applied, such as the building of a new house or structure.
Running sand – Areas are identified where it is possible for sand to run into a void due to water pressure and cause collapse.