Alternatives Evaluation for Compliance with Proposed MCLs for PFOS and PFOA

Geosyntec Consultants, Inc. (Geosyntec) was retained by a client to evaluate alternatives to retrofit their water treatment plant for compliance with proposed New Jersey Maximum Contaminant Levels (MCLs) for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The plant provides drinking water to roughly 40,000 residents via the treatment of ground and surface water, 76% and 24% respectively. The existing facility has a design capacity of 22 million gallons per day (mgd) but has seen a decline in water demand due to business closures, conservation, and high efficiency plumbing systems. In 2017, the plant saw a maximum daily demand of 11.25 mgd and recorded an average daily demand of 8.3 mgd. During Unregulated Contaminant Monitoring Rule (UCMR) 3 sampling conducted in 2015 and 2016, PFOA and PFOS were detected in both the source and finished water to the treatment facility at levels below the United States Environmental Protection Agency (USEPA) Health Advisory Level (HAL) of 70 ppt (USEPA). Although the concentrations of PFOA and PFOS are below the HAL of 70 ppt, they are above the NJDEP proposed MCLs of 10 ppt. Based on our review, Geosyntec decided that Granular Activated Carbon (GAC) and Ion Exchange (IX) are the best alternatives to evaluate for this project. These two technologies are proven to be effective at removing PFOA and PFOS and are continually utilized at other facilities. Through working with vendors, three configurations were developed for GAC, IX, and a combination of the two. Conceptual designs and cost estimates of each were developed for the client.