Given the potential contamination risks associated with former industrial sites Ground and Water was commissioned to carry out all phases geoenvironmental assessment. This involved a detailed desk study, initial site investigation and a more detailed site investigation.
Testing of soil samples from two phases of investigation revealed the presence of heavy metals, including arsenic, lead, mercury and cadmium, in 1.2m of Made Ground below the car park. In addition, asbestos and potentially harmful hydrocarbons were found to be present. The levels of lead, benzo(a)pyrene and asbestos posed a risk to the end users. The asbestos risk assessment was undertaken in accordance with CIRIA733.
A remediation strategy and method statement followed, which were later validated. The remediation strategy included partial removal of the Made Ground present and the creation of a 100mm course grained anti-capillary barrier at the base of the void. This was to be backfilled with certified clean sub-soil and topsoil in soft landscaped areas to create a 600mm clean capping. All material removed from the site was tested, classified and disposed of appropriately. Given the geology of the site it was deemed there was no risk to ground water.