Why is the ʻAiea-Hālawa GAC-IX filter being proposed for removal after 9 quarters? What standards will be used to determine acceptable PFAS levels?

The granular activated carbon-ion exchange (GAC-IX) filter operational duration is flexible and not tied to a specific number of performance periods. Instead, the operational duration is dictated by site-specific conditions, regulatory requirements, and data objectives. The Navy proposal is to remove the filter after nine quarters. However, the filter will remain in place as long as necessary to ensure continued compliance with all regulatory requirements and maintain compliance with drinking water maximum contaminant levels (MCL). Information on federal EPA per- and polyfluoroalkyl substances (PFAS) standards can be found at EPA's Per- and Polyfluoroalkyl Substances (PFAS) website. These standards have been incorporated into the Hawai'i Department of Health's Environmental Action Levels (EAL) Guidance.