A dissolution feature was uncovered within one of the trial pits excavated at the site during a ground investigation designed by CampbellReith in Kent. In the picture you can see the white intact hard chalk on the left-hand side and the soft clay material on the right-hand side which has in-filled the dissolution feature.
Dissolution features frequently occur in chalk and can be naturally caused by acidic rainwater reacting with calcium carbonate within the bedrock, or can be caused by leaking services. They are very tricky to identify and ground investigations within chalk must be carefully designed to ensure that the presence of these features is investigated.
Chalk dissolution features can cause significant issues and structural damage (with associated costs) if not properly accounted for at an early stage of the project. Foundations, embankments, and road pavements can experience significant differential settlement as the soft infill deposits compress under application of load whilst the incompressible chalk does not.
CampbellReith has designed a bespoke foundation solution that removes the risk of structural damage induced by the dissolution feature and we have implemented measures to ensure the installation of new drainage at the site does not induce further dissolution.
Should you have any ground investigation or geotechnical design requirements please contact Josh (firstname.lastname@example.org) or Adam (email@example.com) in the CampbellReith Surrey Office.