The presence of cavities whether natural or man-made poses a risk to development because of the presence of voids or soft or loose infill materials.
In some parts of the UK around 20% of the land area had been subject to mining. Mines may take the form of drift mines, adits, surface workings or shallow and deep mine shafts. Often mines were started speculatively and shortly afterwards abandoned with little or no records of working.
Mining could take the form of workings for coal, ironstone, sandstone, limestone, chalk, metal and clay. In South East England historic features known as Deneholes are frequently found. These are vertical shafts, excavated by hand to facilitate small scale extraction of chalk and flint.
Solution or dissolution features occur in chalk and limestone. These features often known as Sink Holes, often comprise loosely infilled structures or cavities formed as a result of preferential chemical weathering.
Gulls are features associated with the development of valley bulging and cambering in distinct geological conditions in Kent, Sussex and Northamptonshire. Gulls are steeply inclined fissures or joints that have been partially or wholly infilled with overlying material.
We have access to national databases of natural cavities and mine workings. With our extensive ground investigation experience you can ensure that such features are identified during the site investigation and appropriate measures implemented to ensure the suitability for site development.