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Monitoring of soil gas and groundwater levels in-situ is often required as a routine element of the majority of ground investigations, particularly where the potential for hazardous ground gases has been specifically identified as a potential concern as part of the desk study or during the physical investigation works. Monitoring of groundwater levels is also an essential part of both geotechnical and contaminated land investigation.
Monitoring and sampling of groundwater and possible free product is often necessary as part of a contaminated land investigation to identify concentrations of contaminants and determine chemical characteristics. This can range from conventional sampling using bailers in simple standpipe installations to low flow sampling and micro-purging using bladder pumps or other innovative techniques in multi-level installations where complex hydrogeological and contaminant conditions are anticipated. In many cases in-situ measurement of chemical parameters such as pH, Redox, Electrical Conductivity and Dissolved Oxygen is also required.
Applied Geology has the experience and ability to design installation and monitoring programmes and undertake subsequent installation and monitoring of both simple and complex installations for the presence of a wide range of gases, groundwater and products Flow rates can also be monitored, together with other more exotic gases where required. Sampling of soil gas can also be undertaken in Tedlar bags or Gresham tubes for analysis in the laboratory.
This type of work is undertaken as an integral part of the Applied Geology’s investigation process but also specifically for Regulatory Bodies as part of a Waste Management License or validation of a remediation scheme such as in-situ bioremediation or monitored natural attenuation. Applied Geology also offers a contract monitoring and sampling service to other professionals.
Specifically however Local Authorities, under their duties under Part IIa of the Environmental Protection Act, are required to undertake monitoring and sampling of, for example, landfills within their boundaries.
Applied Geology has undertaken this work for a number of Local Authorities by carrying out the necessary monitoring of the soil gas and groundwater and reporting the results to both the Local Authority and Environment Agency, including comments on any abnormal results.
Private landfill operators also have a duty to monitor their landfills as part of their license agreement and this has also been undertaken for a number of clients.
On sites that have been previously investigated by others and now inherited by the new owner/developer it is a very useful option to monitor and sample any probes that have been installed.
The installation of probes, and their continued monitoring and sampling, is also a very useful tool in assessing any environmental impairment to a site caused by its particular use or uses. This is now an important element in entering into new leases for premises.
CASE STUDY
On a particular site of a former scrapyard in Coventry large volumes of methane were detected within a foundry sand infill, but with a low emission rate, probably due to the degradation of linseed oil used as a binder within the foundry sand. In order to quantify the soil gas risk to the proposed residential development a series of flux box tests were undertaken and the data obtained from these tests were used to design a relatively simple gas protection system which was subsequently approved by the Local Authority and National House-Building Council.
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