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PFOS, PFOA and Other Fluorinated Compounds in Environmental Samples: Overcoming Sampling and Analytical Challenges
Heather Lord and Terry Obal
Maxxam Analytics

The objective of this presentation is to provide an overview of perfluorinated compounds, their use and distribution in the environment, with highlights on practical considerations for soil and water sampling and best analytical practices to produce results that are reliable, representative and defensible.

Abstract

Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and related perfluorinated alkyl acids (PFAAs) have received a substantial amount of attention, not only because they are recognized as ubiquitous environmental contaminants, but also because these compounds persist, bioaccumulate and cause toxicity in some animal studies. PFAAs are of particular interest recently because of their emergence as compounds of environmental concern at many sites across North America, and their recent inclusion as an emerging contaminant in the Stage 10 Amendments to the BC Contaminated Sites Rule (CSR).

Over the last several years, requirements for PFAA analyses, and the ability to use the resultant data for risk assessment and management, as well as remedial decisions have increased at an extraordinary rate. Because of the physical and chemical behavior of PFAAs in environmental samples (water, soils and tissue), they pose unique analytical challenges. These same physical and chemical characteristics extend these challenges to field sampling protocols and, if not taken into consideration, lead to unreliable sample integrity and data variability. Ultimately, analytical data will not be representative of the true site condition.

More recently it has been shown that additional polyfluorinated substances may be present in the environment that can be converted to PFAAs by natural oxidative processes. If these are not taken into account during the remedial decision-making process, the magnitude of the required remediation efforts may be significantly underestimated. Supplementary steps are available on request during lab processing of samples in order to report the magnitude of the ‘Total Oxidizable Precursors’ in addition to the current levels of PFAAs.

It is important that we understand the behaviour of both PFAAs and their precursors to ensure representative sample collection, reliable and defensible analytical measurement and ultimately effective treatment of compounds. This presentation will review historic information about the use and distribution of these compounds in the environment, highlighting practical considerations for soil and water sampling, and demonstrating best analytical practices to produce results that are reliable, representative and defensible. 

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Per- and Polyfluoroalkyl Substances (PFASs): Chemistry, Occurrence, Regulation, Mobility and Remediation
Bob Hooley and William DiGuiseppi
CH2M

The objective of this presentation is to provide a brief overview of PFAS sources, regulation and occurrence, but will focus mostly on established and innovative remedial technologies.            

Abstract

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 Environmental Monitoring: How to Ensure Reliable, Representative and Defensible Results 
Heather Lord and Terry Obal 
Maxxam Analytics 

The objective of this presentation is to describe practical water sampling considerations for 1,4-dioxane, demonstrating best analytical practices to produce results that are reliable, representative and defensible.

Abstract

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.

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