Phase 2 Ground Investigations are targeted to the findings of the Phase 1 desk study. Exploratory holes are also formed for general site coverage purposes. Techniques employed could include any of the following: windowless sampling, cable tool percussion boring, trial pitting, hand pitting, rotary drilling, geophysics, sonic drilling, groundwater sampling, permeability testing and surveying. All site investigation works are undertaken by appropriately qualified subcontractors under the close supervision of The Land Consultancy Limited.
Recovered soils are logged and sampled by The Land Consultancy Limited; groundwater samples are also recovered from installed boreholes. Samples are forwarded to UKAS and MCERTS accredited laboratories for analysis.
Statistical analysis of the chemical testing results is undertaken in accordance with current guidelines and the data is then compared to published generic screening criteria, or to criteria derived in house using published environment agency software. Groundwater and leachate testing results are compared to environment agency published Environmental Quality and Drinking Water Standard values.
The original preliminary risk assessment and Conceptual Site Model (CSM) is revisited and updated in light of the findings of the Phase 2 site investigation. The updated now generic risk assessment may indicate that further contaminated related works are not required as non of the pollutant linkages have proven significant. However, the data may remedial works would need to take place to reduce risks to an identified receptor; alternatively, further works could be advised if large amounts of unexpected contamination are encountered (e.g. to define its extent) so that the risks can be quantified.
It should be noted that exploratory holes formed as part of the contaminated land Phase 2 investigation works often obtain the information required when undertaken geotechnical investigations. Ground gas and groundwater levels monitoring surveys are often undertaken on boreholes installed as part of the Phase 2 works.
Please review our case studies page for information on several environmental and geotechnical projects which have been recently completed.
All works must be approved by the Local Authority and Environment Agency (if controlled waters are involved) prior to any contaminated land planning conditions being discharged.
All contaminated land related works are undertaken in accordance with:Government published Contaminated Land Regulation guidance (especially CLR11) Planning Policy Statement 23 BS10175 (2011) 'Investigation of potentially contaminated sites – Code of Practice' BS5930: 1999 (Amendment 2) 'Code of practice for site investigations' CIRIA C665 'Assessing risks posed by hazardous ground gases to buildings' NHBC Standards January 2000 Chapter 4.1 'Land quality – managing ground conditions'.