The overall aim of the Phase 2 Environmental Assessment process is to assess the environmental risk, and to assess potential complete pollutant linkages identified in the Phase 1 desk study. This is achieved through an intrusive site investigation, generally comprising one or more of the following options:
- Excavation of Trial Pits (either by hand or using plant as site conditions allow);
- Windowless Sampling boreholes;
- Rotary Boreholes;
- Cable percussive boreholes;
During the intrusive investigation the ground conditions encountered are observed and logged to BS and Eurocode 7 standard, and any visible or olfactory evidence of contamination recorded. Appropriate soil samples are retrieved from the arisings, placed in suitable containers and subjected to chemical testing at an MCERTS accredited testing laboratory. The testing suite is derived from the Conceptual Site Model detailed in the Phase 1 desk study.
If geotechnical assessment of the site is also required, samples can be taken for geo-technical testing at a UKAS accredited laboratory at the same time as the chemical testing samples.
Where a drilling rig is used to drill the boreholes in-situ Standard Penetration Testing (SPT) is reported as standard to provide further geo-technical information.
Where applicable the boreholes are installed with pipework to allow gas monitoring (if required from an assessment of the risk) and the retrieval of groundwater samples. Groundwater samples are recovered and placed in suitable containers for transport to an MCERTS accredited laboratory at least one week following the installation of the boreholes.
Following the intrusive investigation the results are assessed and used to update the Conceptual Site Model set out in the Phase 1 desk study and identify any potential pollutant linkages. A Generic Quantitative Risk Assessment (GQRA) is developed to assess whether the potential complete pollutant linkages identified in the Conceptual Site Model are plausible. The GQRA is used to evaluate potential remedial actions necessary with respect to the end use of the site.
A Phase 2 report is produced from the above to submit to the Local Authority, to discharge the appropriate planning conditions.