A ground investigation was required to provide geotechnical and geo-environmental data for the design of a residential development and associated infrastructure.
Acting as Principal Contractor, CC Ground Investigations were engaged to undertake a ground investigation to assist in the assessment of contamination across a site in Herefordshire.
The site was formerly occupied by a dry cleaners and a timber yard. Perchloroethylene (PCE) – a chlorinated solvent and the main active ingredient in the dry cleaning process – is known to have leaked into the soils at the site. In addition, a below ground creosote tank, associated with the timber yard in the south of the site, is known to have leaked.
Due to the past land uses and the associated chemicals used during the operation of the former laundry and timber yard, a potential risk has been identified, along with an associated risk of groundwater contamination. The site was identified by the Local Authority as a priority site for further appraisal to assess the categorisation of the site as “contaminated land” as defined under the Environmental Protection Act 1990: Part 2A Contaminated Land Statutory Guidance.
Our in-house Fraste SL(G) multi-purpose drilling rigs and track mounted Terrier drilling rigs were used to undertake the works. In addition to this, CCGI subcontracted European Geophysical Services Ltd to carry out down-hole acoustic televiewing (fracture mapping), natural gamma, resistivity, and fluid temperature and conductivity measurements. All works were supervised on a full-time basis by suitably qualified in-house Engineering Geologists.
Geotechnical logging was carried out to BS5930: 2015+A1:2020, BS EN ISO 14688 [Parts 1 and 2] and BS EN ISO 14689 with detailed discontinuity spacing records. The presence and nature of discontinuities and their vertical and lateral continuity within the Brownstones Formation was important as they were considered to influence the migration of contamination. Further, Sudan Dye screen testing for NAPL was carried out at the time of logging, along with additional geo-environmental sampling for laboratory analysis.
The program of works included:
