An oily sheen containing a chemical contaminant has been found in a drinking water reservoir in Princeville on Kauai. Results from extensive laboratory testing have determined water distributed from the drinking water system does not pose a health threat and continues to be safe. The Hawaii State Department of Health (DOH) and the Princeville Utilities Company Inc. (PUCI) are taking immediate action to protect the purity of the water and the health of residents who depend on it.
On Oct. 16, following routine sampling of drinking water systems across the state, DOH found that minute trace amounts of the organic chemical Aroclor 1254, a polychlorinated biphenyl (PCB), may have been present in a Princeville water system tank on Kauai. The water system tank serves a population of about 1,700 people.
The DOH directed PUCI, owner and operator of the Princeville water system, to conduct testing to determine if PCBs were present and to identify the possible source of contamination.
PUCI sent water samples collected on Oct. 23 and 24 to CalScience Laboratory in California for testing. PCBs were not detected at the tank’s compliance sampling point where water exits at the bottom of the tank, nor at the two wellheads that supply the tank. The DOH collected and tested weekly samples at the compliance sampling point and throughout the distribution system Nov. 14, 19 and 27 and Dec. 4. No PCBs were detected in the samples analyzed by the state Laboratories Division.
“Fortunately, our follow up testing indicates that PCBs are not found in the water that reaches people’s homes,” said Gary Gill, Deputy Director for Environmental Health. “Our Safe Drinking Water Branch is maintaining active surveillance of the distribution system and will continue to monitor and test the water being served to consumers to ensure that the public is protected.”
While PCBs were not detected in the two wellheads, at the tank’s compliance sampling point, nor within the distribution system, the DOH on Nov. 8 learned that PCBs were detected in an oily sheen sample skimmed from the surface of the tank water at 18 parts per billion (ppb). Since water exits from the bottom of the tank and PCBs do not dissolve well in water, this does not represent a health threat. As a precaution, additional water testing is continuing and PUCI is removing the oily sheen from the tank water surface. On Nov. 30, subsequent sampling and testing confirmed the presence of PCBs in the surface sheen at 1.38 ppb. Sampling on Dec. 6 revealed the concentration of PCBs in a skim sample was 1.4 ppb. For more information on PUCI’s mitigation measures, contact Mike Loo at (808) 826-6100.
The source of the oily sheen is still undetermined. Upon findings of PCBs in the oily sheen sample, PUCI immediately took Well #1, an oil-lubed well, out of service. PUCI tested previously used and currently used pre-lube oils used to lubricate Well #1. On Nov. 30, PUCI confirmed that neither of these oils contains PCBs. Well #2 is water-lubed and therefore was not at issue.
The federal and state Maximum Contaminant Level for PCBs is 0.5 ppb at the compliance sampling point. The standard is set to avoid health risks based on a lifetime of consuming water containing that level of contaminant. PCBs are a group of organic chemicals formerly used in the United States in hydraulic fluids, plasticizers, adhesives, fire retardants, and de-dusting agents. PCBs do not dissolve well in water. To date, the Princeville water system is in compliance with federal and state PCB standards for drinking water.