Per- and polyfluoroalkyl substances (PFASs), including those from releases of aqueous film forming foams (AFFF) used to fight flammable liquid fires, have been identified at various sites as compounds of interest and are generally considered emerging contaminants due to their regulatory uncertainty. PFAS contamination may be present at fire fighter training areas, fire stations and related storage facilities (military, civilian and others), at sites where petroleum fires were extinguished or suppressed using foam (automobile and aircraft crashes, petroleum handling facilities, refineries and aircraft hangers) and storage at shore facilities for tankers and military ships. Additionally, industrial uses for stain and water-repellency and lubrication are widespread. These complex compounds have unique chemical properties that control their behaviour in the environment, as well as their toxicity. Because of an increase in awareness and availability of toxicity information, regulations related to these compounds are rapidly evolving, with many agencies issuing new guidance or regulation in the past two years. This increase in regulatory and public scrutiny makes it important to have a better understanding of the chemistry and mobility of these compounds, as well as viable remedial technologies.

Remedial technologies capable of mitigating or destroying PFASs have proven elusive to the environmental consulting industry. The complexities of the AFFF mixtures, which can contain thousands of individual PFAS compounds, limit the capability of many technologies. A variety of remediation technologies have been attempted for treatment of PFASs. Many of these have only been tested or validated on perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), the two most common and most likely to be regulated degradation end-products of AFFF mixtures. While information regarding PFOS and PFOA treatment is useful, it does not answer the broader question of real-world applicability for these technologies. And although these two PFASs are presently the most watched and regulated, numerous other PFASs are being scrutinized, which is likely to lead to additional regulation of others, such as perfluorohexane sulfonate (PFHxS) or 8:2 fluorotelomer sulfonate (8:2 FtS). Recent technology tests, involving oxidation, sorption, thermal, and biological treatment from CH2M and others in academia and industry were evaluated in terms of demonstrated effectiveness and applicability, which will be presented.  

1,4-Dioxane has gained increasing attention as a priority emerging contaminant of concern due to its high mobility in groundwater, resistance to natural attenuation and remedial efforts, and classification by the US EPA as ‘likely carcinogenic to humans’ (2013). Although it is commonly present as a co-contaminant in chlorinated solvent plumes, the extent of 1,4-dioxane impacts on these sites is often poorly defined as historical monitoring efforts typically focused on the chlorinated solvents and did not recognize 1,4-dioxane presence.

1,4-Dioxane is a cyclic ether with high water solubility and moderate volatility. As a result of these characteristics, the standard laboratory protocols for hydrocarbon volatiles are not ideally suited to its determination and the measurement and monitoring of 1,4-dioxane poses unique challenges.

These same physical and chemical characteristics extend these challenges to field sampling protocols and, if not taken into consideration, may lead to unreliable sample integrity and data variability. Ultimately, analytical data will not be representative of the true site condition.

It is important that we understand the chemistry of 1,4-dioxane to ensure representative sample collection, as well as reliable and defensible analytical measurement. This presentation will review current information about the sources and distribution of 1,4-dioxane in the environment, as well as its toxicity and regulatory status. Primarily, it will highlight practical considerations for water sampling, demonstrating best analytical practices to produce results that are reliable, representative and defensible.