GAC/Resin Ion Exchange System Installation, Eareckson AS, Shemya, Alaska

High levels of organic analytes were found in the Eareckson Air Station (EAS) drinking water supply.  A granulated active carbon (GAC) and ion resin exchange (IX) system was selected by the government to treat disinfection by-products caused by organics in the water reacting with chlorine and low levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA).

Brice designed, procured, and installed a self-contained system to bring the EAS water supply into compliance by removing the organics from the water thus minimizing interaction with chlorine, storing more water to provide adequate water for both fire supply and daily water usage, and reducing the PFAS/PFOA contaminants. We worked closely with the client and EAS to understand their operations, needs, and limitations such as production hours, backflushing of existing system, water tank storage requirements, and the sampling protocol and frequency needed to establish design criteria and determine system effectiveness. We then designed the new system to treat 50,000 gallons of water per 8-hour day and installed it between the existing air stripper and disinfection.

Shemya Island weather can be difficult on equipment, and the expense and logistical challenges to ship, repair, and maintain equipment and supplies to EAS are high making it imperative to design a robust, low maintenance system. To achieve this, Brice designed the system to be manually operated with only one GAC and IX resin media changeout per year. The system is also insulated to avoid freezing during the winter months, and the exterior is sand blasted and coated to protect it from corrosion due to the extreme marine environment at that location.

Brice prepared an O&M Manual, reviewed by USACE, USAF, and the Base Operations Support contractor that walks through the startup of the system, media changeouts, backwashing, and sampling protocols for total organic carbon and PFOS/PFOA.