OIL & GAS Groundwater Contamination Trend Analysis Confidential client, UK
Project Summary
Groundwater Contamination Trend Analysis Confidential client, UK
Project Value: £5,000 Key Project Elements Examination of contamination data Plume identification Contaminant concentration trend analysis
CRA carried out regular environmental monitoring of soil and groundwater quality over five years at an industrial site with a historical legacy of hydrocarbon contamination. The monitoring programme was undertaken to determine the potential for contaminant migration towards down-gradient groundwater receptors. Five years of groundwater concentration data was used to identify and monitor contaminated plumes in the shallow and deep aquifers beneath the site. A statistical trend analysis was undertaken to determine whether concentrations in the plumes were remaining stable, attenuating or increasing. CRA used software (developed by one of their main clients) to plot contaminant concentrations, to identify the sources of contamination, and to monitor the progress of plume migration over time. Two separate plumes were identified at the site within the shallow aquifer. The contaminants of concern were volatile petroleum hydrocarbons including benzene. The contaminant concentrations within the plumes and at downgradient wells were analysed to determine if the data was displaying statistically proven trends. It was determined that the contaminants in the wells located down-gradient of the plumes were increasing in concentration; whereas, the contaminants in wells at the source were decreasing in concentration The result of the trend analysis determined that the source is likely from a historical release rather than from an on-going release at the site. The plumes were determined to be moving in the direction of the groundwater flow, in addition with one plume diving towards the deeper aquifer. As the sources were no longer active, the contaminants were found to attenuate over time within the aquifer. CRA worked closely with the client to determine the implications of the contamination with regards to environmental liability and their Environmental Permit, and provided regulatory liaison support to the client throughout the project.
Ref: PS0086