Ground Gas Monitoring & Risk Assessment

A ground gas risk assessment represents a critical element of a Phase 2 (GQRA) contaminated land investigation. To facilitate this, borehole standpipes are fitted with a removable gas valve to enable follow-on monitoring, where readings are undertaken using a calibrated gas analyser, to measure variations in the steady state, peak concentration and flow rate of methane, carbon dioxide and oxygen. The data is then assessed in accordance with BS 8485 risk assessment guidelines to characterise the gas hazard and determine the requirements for any necessary gas protection measures.