A commercial business was planning to relocate its head office to a larger site; a former filling station had been purchased and planning consent obtained, which included conditions relating to contaminated land. The client had commissioned previous work which included a limited site investigation and gas monitoring programme. However, no desk study had been undertaken at this stage.
EES took the project back to first principles and desk study revealed that as well as a filling station, past uses of the site included a domestic waste landfill. This allowed the creation of a preliminary conceptual site model.
We designed a site investigation, which included the installation of gas and water monitoring wells across the site. Soil analysis augmented with a robust gas and water monitoring programme, revealed old tanks and gross contamination of soil and groundwater with the potential to impact on a nearby Special Area of Conservation. An unacceptable gas risk was also discovered across the site.
In order to refine the conceptual site model, a risk management strategy was drawn up, which included the decommissioning and removal of underground tanks, removal of grossly contaminated material and a groundwater treatment system.
And the benefits
Through the use of detailed quantitative risk modelling, We were able to generate site specific remediation targets for soil and groundwater. Decommissioning of the tanks and associated lines removed the contamination source. The groundwater treatment system was designed so that building work could begin while it was still in operation. This enabled the client to meet deadlines regarding business grants. We also worked with the architects to include appropriate gas protection measures in the building design in order to mitigate the gas risk.
Our expertise in both stakeholder and regulator liaison enabled remedial and building work to progress while regulatory requirements were met.