21May / 2011
Project Title: Due Diligence, Middlesbrough
Client: Multi-national Consultant
Project Start date: June 2010
Project End Date: July 2010
- Inspection and appraisal of existing gas protection measures
- Generic Quantitative Risk
- Assessment for Ground Gas
- Outline Costs for completing remediation
Due Diligence, Middlesbrough
Inspection of Existing Gas Protection Measures and Detailed Ground-Gas Risk Assessment
Ground-Gas Solutions (GGS) was commissioned as a specialist consultant to a leading multi-national consultancy firm to carry out a comprehensive ground-gas risk assessment of an operational chemical works in Middlesbrough as part of the diligence process. The scope of works included an inspection of existing building gas protection measures, review all existing site investigation and risk assessment information and undertake high-frequency bulk gas monitoring and trace gas analysis. This project was completed under strict limited time constraints.
GGS also recommended remedial measures considered to be necessary at the site along with their likely costs for capital expenditure and / or other compliance costs.
GGS operated under a ‘hot permit’ to work systems and in compliance with the works operator’s strict health and safety procedures.
The intrusive investigation was undertaken by the multi-national consultancy and comprised 14 No. ground-gas boreholes and installation of monitoring wells. GGS conducted the ground gas monitoring (spot sampling and high frequency) as a specialist element of the main site investigation.
The high frequency monitoring was completed using GGS’s innovative GasClam® equipment. This device takes high frequency (‘continuous’) readings of methane, carbon dioxide, oxygen and some trace gases along with other environmental parameters, generating a better understanding of the gas regime for interpretation. This type of information proved to be extremely useful as a more detailed site specific conceptual model was built up and the true gas regime at the site was determined.
Risk Assessment and Conclusions
A full detailed ground-gas risk assessment along with outline costs for completing the recommended remedial mitigation measures was undertaken. The generic risk assessment highlighted a moderate gas contamination risk at the site. GGS assessed the existing measures against BS8485:2007. On the basis of these assessments recommendations for minor remedial mitigation / maintenance measures of the existing gas protection measures were provided for inclusion in the due diligence report.