Extensive investigations have already been carried out on site to identify the nature, degree and location of contamination, including pilot tests and laboratory trials to establish which treatment methods would work best for the conditions found on site. A single type of treatment for the entire site will not be effective due to the different physical variation of soils (some soils are more clay-like, and others more sand-like) and the variety of chemicals found contaminating the site. Therefore a range of suitable techniques has been agreed.
The agreed overall method for remediation can be described as Ex-Situ Bioremediation, which means the excavation and treatment of soils through physical and biological processes. The aim of the process is to remove all uncertainty relating to soils and groundwater within the site area by excavation, characterisation and treatment of all impacted soils and groundwater.
The excavations will proceed slowly so that material can be assessed, as it is uncovered. The assessment takes into account the nature of contaminants and the type of soil (i.e. sands or gravels or clays) so that it can be directed to different areas of the site for the correct form of treatment.
During remediation, soils will be sampled and tested and only soils that fully comply with the agreed remedial targets will be placed back into the ground.
In addition to the remediation of the soils, groundwater will be pumped from the excavations and transferred to the existing Waste Water Treatment Plant (WWTP) situated to the west of the A10. Whilst the WWTP has been used to treat the groundwater from the site for many years, it has been modified to improve its efficiency throughout the remediation works.
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