Our ability to measure hazardous ground gases and vapours or detect low levels of dissolved phase contaminants in ground water rather than relying on conservative and poorly constrained modelling has improved in recent years.
New technologies are enabling real time data to be collected. New data analytical techniques are providing greater insights in the composition and potential origins of hazardous gas, vapour or dissolved phase contaminants.
For example so-called “emerging contaminants of concern” (around since the 1950s!) such as per- and polyfluoroalkyl substances (PFAS), and their brominated cousins, provide laboratories with exciting challenges to attain the detection levels required by regulators but also to help us understand the potential future risks they may pose. Conventional tests for PFAS measure a discrete list of up to about only 30 compounds and are not designed to quantify the suite of pre cursor compounds that may exist in soil and groundwater. Hence there are many additional PFAS compounds present at sites and within environmental samples that will not be determined during routine analysis. If you consider the environmental biotransformation processes that occur in biological waste water treatment plants, where significantly more PFOA and PFOS are measured at the outflow than the inflow, then you can begin to understand the importance of also identifying the important “precursors” to the perfluoroalkyl acids (PFAAs) to help us avoid underestimating the potential PFAS risk present in the environment. A new technique being offered by UK based labs is the Total Oxidizable Precursor (TOP) assay, which helps to quantify the concentration of non-discrete and difficult to measure PFAS compounds that are not determined by conventional analytical methods. Assessment of TOP assay data can help us to improve the potential risk from PFAS across a range of sites and situations.
Guidance has been available for many years on assessing the potential human health risks arising via vapour intrusion internationally (e.g. the US and Australia), although within the UK field sampling techniques and guidance is less well developed, early work was carried out by the late Colin ferguson and Victor Krylov. For example in a UK context when taking vapour samples, there is a lack of definitive UK guidance on what are the best tracer techniques to use with many relying on the use of a potentially significant cross-contaminant iso-propyl alcohol (IPA) which can compromise your vapour results, cost you time and money and can cause problems for the laboratory. Helium is a generally accepted, but costlier, preferred inert tracer of choice, and is becoming increasingly favoured where low limits of detection for your volatile organic compounds are required for sensitive land use risk assessments.
These are just some of the developments within the gas and groundwater sampling and analytical practices that contaminated land practitioners should be familiar with to help ensure they continue to provide sound advice to and defensible decisions for their clients and regulators.
As part of our continued commitment to raising standards among practitioners and regulators, LQM’s next Professional Practice Webinar, delivered by Paul Nathanail, will explore the role innovative sampling and analytical techniques have in better managing land contamination on post- industrial brownfield sites or, the rare, Part 2A sites.
You can find out more and book a place by visiting https://www.lqm.co.uk/webinars/ggwweb/