Consultants conducting ground gas investigations on contaminated land and brownfield sites can now lease the CIRIA (construction industry research and information association) compliant GA5000 portable landfill and contaminated land gas analyzer from Geotech.
Ground gas investigations are typically undertaken as part of Phase II geo-environmental assessments, and are a planning condition for many proposed developments. Occasionally a stand-alone investigation may be required, where development sites or existing structures are potentially affected by ground gas.
Many consultants currently use CIRIA C665 as guidance for ground gas investigations, assessing the risk posed by hazardous ground gases to buildings.
This guidance recommends a minimum of 3 months’ monitoring for a site with low potential of source gas generation. Typically, investigations will include the installation of several gas monitoring wells which will undergo a series of regular monitoring schedule to monitor for any gases, mainly methane and carbon dioxide, as well as measuring flow. Some wells will also be targeted for checking for low or falling atmospheric pressure, as this would indicate the land may no longer be producing gas and potential remediation or building could begin.