The high number of subsidence events around Briars Lane in Hatfield, Hertfordshire since 1978 - resulting in the demolition of four houses - prompted Welwyn Hatfield Council to ask Soil Mechanics to investigate the layout, lateral extent and nature of any cavities in the substrata. Subsidence is believed to be due to old chalk mine workings, and the ground investigation specialist is using a variety of techniques over two phases, including dynamic probing, cable percussion and rotary drilled boreholes, microgravity and resistivity surveys and window sampler boreholes with CCTV. The first phase of work was carried out between November 2004 and February 2005, with the second due to start in March.
www. mesg. co. uk/ soilmechanics