Omnia Consulting were commissioned by a national house builder to undertake a ground gas assessment on one of their sites within southern Hampshire, which led on to follow-up validation works and reporting on the gas protection measures needed for the site.
Earlier site works had been undertaken by previous sub-contractors across the former site with monitoring installation points previously constructed. Historical data identified the site as a decommissioned landfill site by 1994.
Initial monitoring was undertaken across the site showing elevated concentrations of carbon dioxide and methane. We attended site for a further three months to undertake continuous gas monitoring enabling us to produce a ground gas risk assessment, based on the results of the assessment we deteremined that gas protection measures were only needed in the central zone of the site which was classed as a high risk.
Using the zoning plan, protection measures were designed and carried out by our client, with validation and integrity testing undertaken by an accredited subcontractor, which was supervised by one of our consultants. Validation techniques included:
- Visual inspection,
- Mechanical Point Stress Test,
- Air Lance Testing of all welds and seams; and
- Integrity testing using Tracer Gas.