HGL Highlights Its Full-Service Capabilities and Innovative Cost-Saving Technology for Supporting Sites with the Emerging Contaminants PFOS and PFOA

Emerging Contaminants
Emerging contaminants are chemicals that have not been regulated or investigated historically but that, based on some technical evidence, may present a risk to human health or the environment. Recent examples are per- and polyfluorinated alkyl substances (PFAS), including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which have been generating particular interest and concern in the United States and abroad. Although the U.S. Environmental Protection Agency (EPA) has established health advisory levels for PFOS and PFOA, and some states are beginning to regulate them, comprehensive federal regulations for these two chemicals and other PFAS compounds have not been promulgated. As a consequence of limited and evolving regulatory requirements, many sites where PFAS compounds have been released have not been well characterized. Limited information exists to determine the extent of these contaminants in the environment, and significant uncertainty remains about the potential health and ecological effects, liability, treatment technologies, and cleanup goals associated with them.

History of Production and Use

PFAS compounds have been produced since the mid-20th century and have been used in the manufacture of numerous items including textiles and leather products, food packaging, non-stick cookware, stain-resistant carpets and upholstery, paper products, industrial surfactants, and semiconductors. In addition, firefighting materials such as aqueous film forming foams (AFFF) have contained PFAS. These foams have been stored and used for fighting fires and for conducting firefighting training by local fire departments, at hundreds of military installations and civilian airports, and at petroleum and chemical manufacturing facilities throughout the United States. Primary sources of PFAS therefore include industrial areas and fire training/fire response sites. Because PFAS compounds do not degrade or break down in the environment, they are also commonly found in landfill leachate and wastewater treatment plant effluent.

PFOS and PFOA have become a crucial concern to the Department of Defense (DoD), primarily because of the use of the compounds in AFFF, and DoD is committing significant resources to mitigate potential risks associated with the chemicals. According to a report prepared by the Government Accountability Office in October 2017, DoD has restricted use of the current formulation of AFFF and begun to develop a new foam that meets its performance requirements. The National Defense Authorization Act for Fiscal Year 2018 is requiring DoD to report on its progress in developing alternatives to AFFF that do not contain PFOA or PFOS.

Possible Health Effects

According to the Agency for Toxic Substances and Disease Registry, preliminary data suggest that exposures to PFAS are associated with adverse effects on human reproduction and growth, learning, and behavior in children; high cholesterol; decreased immune response; and elevated risk of cancer. EPA also has found evidence suggesting that PFOS and PFOA may cause cancer.


Groundwater Pump-and-Treat Facility

Mitigation and Remediation Measures

A fact sheet on PFOS/PFOA prepared by EPA in November 2017 states that most conventional chemical and microbial treatment technologies have not been effective in remediating the compounds. Pump-and-treat with ex situ treatment using granular activated carbon, ion exchange resins, and reverse osmosis have been demonstrated to be effective for treating water contaminated with PFOS/PFOA. Notably, granular activated carbon is the most commonly employed treatment technology.




HGL Services

As listed below, HGL offers proven experience and expertise in investigating and mitigating PFAS compounds. Please click on these links for additional information.


HGL is completing PFAS characterization and mitigation work nationwide.

HGL completed Preliminary Assessment (PA) activities at 82 DoD installations nationwide where releases of AFFF containing PFAS could have occurred. HGL performed historical research and interviews, visited and inspected the 82 sites, and prepared PA reports that evaluated whether probable releases of PFAS from fire training activities, fire suppression system testing and use, and fire and emergency incident response actions had occurred.

HGL is currently providing the following related services:

  • Mitigating drinking and surface water for PFOS and PFOA;
  • Replacing AFFF stockpiles; and
  • Providing subject matter expertise and support in multiple PFAS areas.




HGL offers 30 years of experience executing the full suite of CERCLA/RCRA investigation and response services.

CERCLA Process

Former Fire Training Area with Nose of Plane Fuselage

HGL provides cradle-to-grave services for sites with chemical-, radioactive-, and munitions-related contamination issues. For example, HGL completed CERCLA PAs for over 80 sites nationwide to determine if releases of PFOS/PFOA could have occurred and is now mitigating those compounds using granular activated carbon and ion exchange treatment technologies at four sites. HGL has consistently demonstrated its ability to complete effective investigations, prepare human health and ecological risk assessments, design innovative remediation systems, and successfully and safely complete soil and groundwater restoration efforts. HGL also knows from its experience at PFAS sites that mitigation efforts must sometimes follow an expedited process involving completion of a Time-Critical Removal Action (TCRA) or Non-Time Critical Removal Action (NTCRA) with an Engineering Evaluation/Cost Analysis (EE/CA) as well as an Action Memorandum.

Treated Effluent Tank, Influent Equalization Tank, and GAC Treatment Vessels

Throughout each project, HGL seeks to optimize site characterization as well as the design and operation of remediation systems to reduce cleanup times and associated costs. HGL knows that understanding mass distribution in the subsurface, mass flux from permeable/impermeable units, the effects of subsurface heterogeneity, and matrix diffusion are key drivers for effectively characterizing a site and for delivering a successful remedy. Drawing upon its knowledge and experience and using both innovative treatment technologies and proven methods, HGL develops sustainable remedies that, to the extent possible, allow for beneficial reuse of site property.




HGL offers innovative cost-saving decision support technologies for site characterization and remedy design and optimization.

PBMO Medallion Conceptualization

HGL is a prominent leader in modeling groundwater and surface water to visualize and predict contaminant transport, estimate cleanup time frames, and manage water resources. Modeling is a valuable tool that allows designers and engineers to understand the behavior of a dynamic system and support technical and managerial decision-making. HGL’s Physics-Based Management Optimization (PBMO) software links advanced optimization algorithms with site flow and transport models and integrates multiple variables and constraints into the decision process at a level of detail previously considered impractical. For each site, HGL considers the conceptual site model, the goals of the remedy, available data, remedy performance, protectiveness, cost-effectiveness, and closure strategy. PBMO earned the Grand Prize in the Innovative Research category of the 2017 Excellence in Environmental Engineering and Science competition. The annual international competition, organized by the American Academy of Environmental Engineers & Scientists®, has been rewarding the best in current environmental engineering and science since 1989.

PBMO has been customized for emerging contaminant site applications as follows:

  • Plume Delineation and Tracking: Enables stakeholders and decision makers to base plume migration on a solid foundation by identifying plausible plume locations and optimal new well locations
  • Source Finding/Location Identification: Identifies source location for determining the nature and extent of groundwater contamination
  • Optimal Monitoring Well Network Design: Positions monitoring wells to maximize information content at a specific point in time
  • Optimal Pump-and-Treat System Design: Uses PBMO for optimizing new remedial designs and existing pump-and-treat systems
  • Long-Term Monitoring Optimization: Identifies an optimal and cost-effective sampling frequency and spatial density to document long-term aquifer restoration and protectiveness
Optimal Methodology for Plume Delineation with Quantified Uncertainty

Optimal Methodology for Plume Delineation with Quantified Uncertainty








– Agency for Toxic Substances and Disease Registry. Per- and Polyfluoroalkyl Substances (PFAS) and Your Health at URL https://www.atsdr.cdc.gov/pfas/health-effects.html.
– Interstate Technology & Regulatory Council (ITRC), 2017. Per- and Polyfluoroalkyl Substances (PFAS) Fact Sheets at URL http://pfas-1.itrcweb.org/wp-content/uploads/2017/11/pfas_fact_sheet_introductory__11_13_17.pdf.
– ITRC, 2017. History and Use of Per- and Polyfluoroalkyl Substances (PFAS) at URL http://pfas-1.itrcweb.org/wp-content/uploads/2017/11/pfas_fact_sheet_history_and_use__11_13_17.pdf.
– National Ground Water Association, 2017. Groundwater and PFAS: State of Knowledge and Practice at URL http://www.ngwa.org/Media-Center/news/Pages/Groundwater-and-PFAS-State-of-Knowledge.aspx.
– U.S. Congress. H.R.2810 – National Defense Authorization Act for Fiscal Year 2018 at URL https://www.congress.gov/bill/115th-congress/house-bill/2810/text.
– U.S. Environmental Protection Agency, 2017. Technical Fact Sheet – Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) at URL https://www.epa.gov/sites/production/files/2017-12/documents/ffrrofactsheet_contaminants_pfos_pfoa_11-20-17_508_0.pdf.
– U.S. Government Accountability Office, 2017. Drinking Water: DOD Has Acted on Some Emerging Contaminants but Should Improve Internal Reporting on Regulatory Compliance at URL https://www.gao.gov/assets/690/687822.pdf.
– Water Quality Association. Contaminants of Emerging Concern at URL https://www.wqa.org/whats-in-your-water/emerging-contaminants.
– Witteveen+Bos and TTE Consultants, 2016. Questionnaire on Contaminated Land Management in Europe: Emerging Contaminants at URL http://www.emergingcontaminants.eu/application/files/8714/2969/8847/questionnaire_EC_v22-04-2015.pdf.