Gas can accumulate from either natural or man-made sources e.g. made ground or landfill sites. Ground gas is explosive, if the Phase 1 Desk Study identifies a risk of potential ground gas accumulation on the site; Gas Monitoring and a ground gas risk assessment will be required.
In order for Gas Monitoring to be carried out, a borehole installation is necessary. This involves drilling into the ground and installing a borehole with slotted pipe which allows for the accumulation of gas. This must be done in accordance with British Standards. The boreholes are capped and monitored over a period of time which is 12 months in line with CIRIA Guidance. At least one reading must be taken when the atmospheric pressure is below 1000 mbar.
- Methane (%)
- Carbon Dioxide (%)
- Oxygen (%)
- Gas Flow Rate (l/hr)
- Atmospheric Pressure (mbar)
- Groundwater Level (m bgl)
When the monitoring is complete, a risk assessment report is issued in accordance with CIRIA Guidance and will clearly recommend what gas protection measures are needed, if any.