D. Fiereck
Loureiro Engineering Associates, Inc.,
United States
Keywords: PFAS, drinking water
Summary:
The Challenge is that PFAS contamination in drinking water nationwide impacts 145 million Americans. The common solution for drinking water sources, where PFAS exceeds the EPA promulgated standards, is to build an ex-situ treatment system that adsorbs the PFAS onto carbon or resins for off-site disposal. The capital and operation and maintenance costs for these systems is significant and a monetary hardship on most of the municipalities or water suppliers. Typical costs for small to mid-size communities is in range of several million dollars in capital and hundreds of thousands of dollars in annual operation and maintenance. Another significant concern for the communities and water suppliers is the high uncertainty associated with the regulatory and technical developments ongoing for PFAS with respect to risks and treatment options that are rapidly changing. While the EPA is currently focused only on PFOA and PFOS, there are projected to be many thousands of PFAS compounds for which we have limited to no risk data. With the significant potential expenditures for standard ex-situ treatment systems and the significant unknowns associated with the regulations and technology for PFAS, it is prudent to consider alternative permanent or temporary solutions that could be significantly more cost-effective. Use existing technologies in a novel manner to provide municipalities and water suppliers the opportunity to eliminate or delay the high costs of ex-situ treatment by providing a permanent or multi-year window of PFAS treatment to both allow developments in the regulations for PFAS and also for more cost-effective PFAS treatment technologies to be developed into commercially available products. In the approach: • High-flux PFAS pathways, i.e. “hot zones”, in the drinking water aquifers are identified • Activated carbon is injected into these target aquifer zones to form an in-situ permeable filter barrier to intercept the PFAS before it enters the production well(s), reducing cost, complexity, and disruption for the communities • The process is flexible in deployment to provide for permanent or temporary (multi-years) solutions The Process: • Assessment: 3D PFAS and hydraulic conductivity mapping • Design: Filter wall geometry and dosing determined based on PFAS mass flux • Installation: Carbon filter is injected using standard well-based methods We have evaluated this process for two New England communities and potential costs savings ae on the order of 80 percent on capital costs and 100 percent on operation and maintenance costs. This presentation will provide more details on the process and process limitations and the potential cost savings.