The Guam Waterworks Authority is expected to initiate a treatment system assessment this week at one of the wells found to have high levels of perfluorooctane sulfonate (PFOS). Five other wells were found to contain the compound, while three of those wells had concentration levels higher than recommended by the U.S. Environmental Protection Agency.
As part of mitigation efforts, GWA shut down the three wells and is waiting on lab results from additional monitoring that has been conducted. The well in Tiyan, called NAS-1, was taken offline on Aug. 12.
The treatment system attached to the well is owned by the A.B. Won Pat International Airport Authority, according to GWA General Manager Miguel Bordallo. The treatment system was originally meant to clean the well of trichloroethylene (TCE) and perchloroethylene (PCE), toxic chlorinated hydrocarbons, which was the airport's responsibility. However, treatment of PFOS is not required of the airport.
Concentration levels of TCE and PCE compounds have been present but have not exceeded standards. However, the treatment system has not been maintained despite requests from GWA, Bordallo said. The airport authority has pointed to issues with leaking valves and piping as reasons for delaying maintenance on the actual treatment system, he added.
'We're willing to take over'
"GWA has already expressed to the airport that we're willing to take over the treatment system at our expense. But we don't own it, they own it. So they kind of have to agree to let us take it over," Bordallo said.
The assessment is to determine the specific issues with the treatment system, which the airport authority has not yet identified. If the system is rehabilitated, it will be used to treat water for PFOS and the well will be brought online again, Bordallo added.
The two other wells, called A-series wells, were taken offline on Aug. 5 and, while there are plans to bring them back online in the future, there are no treatment systems attached to these wells.
"We're looking at procuring a mobile treatment system that we can put down next to either well and just pipe (water) up and then it will provide the treatment," Bordallo said.
'Blending is an option'
Prior to shutting down the A-series wells, the contaminated water from the wells blended with water from other sources in the distribution system, reducing the concentration of PFOS and making the water safe to drink, according to previous statements from Bordallo. Blending remains an option, he added, but additional improvements on the distribution system are needed to make this an effective option. When the water from the A-series wells is blended, it creates lower pressure in certain areas due to a pressure reducing valve. The valve must be fixed before it can accommodate blending, Bordallo said.
"Blending is an option but what we'd like to do is still provide treatment before we blend," he added. Work on the valve is scheduled to begin this week, according to GWA documents.
Other wells within the surrounding area of the affected wells may contain elevated PFOS levels as well and the utility is waiting on lab results to determine if it is necessary to address these wells.