Protecting People and the Environment from a Hazardous, Widespread Chemical

PFAS – an acronym for per- and polyfluoroalkyl substances – are very persistent, highly toxic chemicals that are very mobile in the environment. They also bioaccumulate and become more concentrated in the bodies of living things, similar to the way mercury bioaccumulates in fish.

“Unlike most other classes of contaminants, PFAS chemicals do not appear to naturally degrade to less toxic compounds,” said Matt Burns, leader of contaminated land services at WSP. “Their widespread and long use history has given PFAS time to disperse in the environment through water and air to such an extent that most people in the U.S. have one or more PFAS compounds in their blood.”

PFAS chemicals are extremely stable compounds designed to resist degradation. This class of thousands of compounds has been manufactured since the 1940s and was widely used in a variety of industrial and household products for more than a half century, including:

• firefighting foam (aqueous film forming foam)
• stain- and water-repellent fabrics
• paper products with surface coatings (such as pizza boxes, sandwich wrappers and microwave popcorn bags)
• non-stick products
• cosmetics, sun screen and bug spray
• metal plating
• electronics manufacturing

These substances are being voluntarily phased out by several manufactures and are no longer manufactured in the U.S. But they are still produced internationally and can be imported in consumer goods.

“Left unchecked, these compounds are likely to persist in the environment well after phase outs are complete,” Burns said. “In addition, many of their replacement substances, which are still in use, are also toxic.”

The two most studied and toxic of the PFAS chemicals are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). These chemicals present a health concern potentially as dire as any others historically monitored by the Environmental Protection Agency (EPA), which set the drinking water lifetime advisory levels of 70 parts per trillion for total PFOA and PFOS.

“To put this concentration into perspective, it is equivalent to 70 seconds in 31,500 years,” Burns said. “The Safe Drinking Water Act maximum contaminant level for commonly encountered pollutants trichloroethene (a chlorinated solvent) and benzene (a component of gasoline) is 5 parts per billion. Using the time analogy, that is 5 seconds in 31.5 years.

The health advisory level for total PFOA and PFOS is orders of magnitude lower, meaning much less of PFOA and PFOS in drinking water is a concern. Further, many local and international jurisdictions are setting even lower advisory levels and criteria than the EPA.

Even though the PFAS has not received as much media attention as other environmental issues, such as climate change and ozone depletion, the persistence and prevalence of PFAS chemicals make it a simmering threat that should be mitigated to minimize the spread of adverse effects on human health and the environment.

“The phase out of PFOA and PFOS has had a positive effect of reducing exposure to these chemicals,” Burns said. “However, residual PFOA and PFOS and their similarly toxic replacements will persist and disperse within the environment. As these chemicals disperse, the number of impacted communities will increase, as will the need to protect existing drinking water sources and identify new ones.”

WSP has been addressing PFAS remediation as one of the firm’s commitments to create a world that is Future Ready™—thinking beyond the conventional to help organizations prepare for the changes and challenges the world will face, and improving the overall quality of life through information, thoughtful solutions, and approaches that will have a positive impact on our environment.

“We are advising and addressing the immediate compliance and liabilities organizations face, while planning for likely future regulatory requirements, as the EPA incrementally rolls out regulatory drivers for the thousands of PFAS compounds,” Burns said.

Successful remediation of PFAS contamination requires careful analysis from the onset to identify and characterize the situation and determine the most effective remediation approach.

Challenge 1: Identification. There are thousands of PFAS compounds, but analytical methodologies have been developed to reliably achieve detection limits consistent with current advisory levels and criteria for 25 to 50 PFAS compounds and their “parts per trillion” levels.

Challenge 2: Quantify. While effective techniques are available to quantify the most common 25 to 50 compounds, measuring other compounds outside those parameters can be problematic, though not impossible. “Non-targeted analytical procedures are available that can provide concentration information for less common PFAS,” Burns said, “but at increased cost and time.”

Challenge 3: Plume Characterization. Lack of regulatory criteria in the U.S.—as opposed to non-enforceable EPA health advisories—limits delineation efforts to measure the extent of impact of the contaminants. Normally delineation is completed to an enforceable criteria endpoint, such as established drinking water maximum contaminant level.

Challenge 4: Remediation. PFAS were built to be stable and do not significantly degrade naturally in the environment and engineered in situ microbial and chemical processes appear to have little effect. Many ex situ treatment processes are available to treat PFAS affected groundwater once pumped from the ground. Accordingly, hydraulic containment using pump and treat systems are commonly used to address PFAS plumes.

“WSP has experience with these systems and is adapting aspects of the ex situ treatment systems for in situ deployment,” Burns said. “In situ deployment is expected to provide significant cost savings and a much lower environmental footprint, such as carbon and hazardous air pollutants, than comparable pump and treat systems.”

Challenge 5: Disposal. PFAS soil treatment options rely on separating or washing the chemicals from soils, chemically stabilizing and isolating them or high temperature incineration. Landfill disposal of affected soils is available at select facilities, but at high costs.

Despite the challenges, the long-term benefits are proving to be worth the effort.

“Without remediation, many communities will face challenges of keeping drinking water sources PFAS free by finding alternative water sources or treating affected water before distribution,” Burns said.

Another exposure that could affect many communities is use of contaminated biosolids from municipal wastewater treatment plants as fertilizer on agricultural crops. Plants may take in PFAS that are later consumed by people and livestock where they bioaccumulate. PFAS bioaccumulation occurs in natural forage as well, and several “do not consume” advisories have been issued for fish and game in heavily contaminated areas.

WSP’s global contaminated land leadership has established a PFAS expert working network to transfer knowledge and leverage experience. The U.S. has benefited greatly from the firm’s international colleagues.

“The magnitude of the problem necessitates a management approach that is based on engineering economics and sound science,” Burns said. “WSP uses plume management tools to identify and prioritize placement of hydraulic control and passive treatment systems to interrupt exposure pathways and protect critical natural resources.”

In addition, WSP also routinely include PFAS review within standard environmental reviews for transactional support, and if contaminants are present, advise the organization on liability costs and management alternatives.

The firm also advises municipal clients on existing advisory levels, expected drinking water maximum contaminant levels, and potential future regulatory actions. Water supply and reuse services are expected to increase as PFAS-impacted resources are identified and municipalities needing to identify new and maximize the longevity of existing drinking water sources.

“Globally, WSP is at the forefront of PFAS investigation and remediation,” Burns said. “WSP has the demonstrated technical expertise to quantify soil-to-groundwater and groundwater-to-surface water mass flux/mass transport. This skill set, combined with the expertise in risk assessment, digital optimization, high-resolution site characterization, ecology, remediation, water supply and water reuse, are true industry differentiators for WSP.