Site Investigation

Site Investigation

At TGEN, a site investigation undertaken to gather information for a Tier 2 GQRA or DQRA is carried out in accordance with BS10175:2011 Investigation of Potentially Contaminated Sites – Code of Practice.

If necessary a site investigation together with suitable chemical analysis of soil, leachate and/or water samples, ground gases etc. is designed and implemented by TGEN in order to gather sufficient information to provide quantification of the risks identified within the Phase 1 PRA and to inform a Phase 2 GQRA or Phase 2 DQRA in determining the need for remediation. The site investigation itself may be split into several sub-phases, dependent upon the size and scale of the site as detailed in the following sections.

Exploratory Investigation

An exploratory investigation is often used on sites identified as a low risk as part of the Phase 1 PRA in order to confirm that assessment. For more complex sites or those allocated a higher risk, TGEN may implement an exploratory investigation as a precursor to, and to inform the design of, a main investigation. If implemented, an exploratory investigation would be designed to:-

  • Test the contamination and site characteristics identified within the preliminary CSM.
  • Obtain further information in relation to potential sources of contamination, likely pathways and features of immediate concern.
  • Obtain further information on the geology, geochemistry, soil, hydrogeology and hydrology of the site.
  • Provide further information to aid the design of a main investigation, including health and safety aspects.
  • Provide data for a review of the CSM and to update the risk assessment.

Main Investigation

The main investigation would be designed by TGEN to:-

  • Obtain data on the nature and extent of contamination, the geology, geochemistry, soil, hydrogeology and hydrology of a site.
  • Provide data to review the preliminary CSM and to update the risk assessment.
  • Provide data for the selection and design of remedial works.

Supplementary Investigation

In cases where an exploratory and/or main investigation highlight specific issues at a site then TGEN would design a supplementary investigation(s) in order to:-

  • Provide clearer delineation of a particular area (zone) of contamination or a contamination plume.
  • Address or clarify specific technical matters (e.g. to confirm the applicability and feasibility of potential remedial options or obtain information for their design).

In-Situ Testing and Monitoring

Where necessary, during the intrusive investigation(s), an assessment of soils for the presence of volatile organic compounds by visual and olfactory means is supplemented with the use of a PhoCheck Plus 2000 Photo-Ionisation Detector (PID) to test for the presence ionisable volatile compounds (VOC).