Envirotreat Technologies Ltd was commissioned by Willmott Dixon to design and install an E-Clay Permeable Reactive Barrier [PRB] at a former landfill site in Walton on Thames, Surrey. The local authority intends to develop the site for a new leisure complex (running track, sports fields, etc.). The prime purpose of the PRB is to protect the prime offsite receptor (the River Thames) – the Environment Agency required the installation of the PRB prior to the commencement of the enabling works to address potential risks associated with the migration of contaminated groundwater during the enabling works (as a consequence of disturbance effects). The prime contaminants of concern were total petroleum hydrocarbons, BTEX and ammoniacal nitrogen. Envirotreat attended site in November 2015 and carried out a focused site investigation to provide information on the geology and contamination in the western area of the site (the proposed PRB location) – samples were taken and batch/column testing was undertaken to support the proposed design.
The approved PRB design was installed during May / June 2016. The barrier was installed by in-situ soil mixing using a continuous flight auger [CFA] to the required depth.
Leap Environmental were the environmental consultants for the project.
The photograph shows the installation of the PRB utilising the CFA