For the first time, a Honolulu Board of Water Supply monitoring well, located southeast of the Navy’s Red Hill fuel facility, tested positive for a set of chemicals that are associated with fuel, including carcinogens, the utility said Thursday. 

The civilian drinking water system remains safe, BWS said. But a well in the Moanalua Valley – which is used solely for monitoring water, not for drinking – was found to contain trace amounts of polycyclic aromatic hydrocarbons, according to Erwin Kawata, a BWS program administrator.

Polycyclic aromatic hydrocarbons are a class of chemicals that occur naturally in coal, crude oil and gasoline, according to the Centers for Disease Control and Prevention. Some of the PAHs detected in the well are suspected or known to cause cancer. 

The well, called DH-43, is on private property just over a mile from BWS’ Moanalua drinking water well.

“It’s certainly a concern, but it’s not at a point where we’re panicking,” he said in an interview. “It’s something we need to watch.”

The Hawaii Department of Health and the Environmental Protection Agency have been briefed on the detections, BWS said, adding that both agencies will review the test results and may take additional testing samples.

Board of Water Supply officials believe the detections are a sign that leaked fuel from the Navy’s World War II-era facility may be moving eastward, which they said is surprising. Experts in Oahu’s groundwater flow have believed for years that water and fuel in the aquifer under Red Hill naturally flowed toward Pearl Harbor and could possibly move westward, toward Halawa. 

“This latest detection of PAH and TPH contamination in DH-43 significantly heightens the BWS’ concern that fuel contamination from the Red Hill facility is travelling through Oahu’s sole-source aquifer,” BWS manager and chief engineer Ernie Lau said in a press release Thursday. “The recent contaminant detections in our DH-43 monitoring well are warnings that we cannot ignore.”

The Navy said it had not yet seen the BWS data.

“The Navy continues to actively collect samples from monitoring wells located in and around Red Hill. The Navy is sharing all data from its monitoring wells weekly with the regulators, interested stakeholders, and the public,” spokeswoman Lydia Robertson said in an emailed statement. “We welcome an opportunity to review BWS’ data so that all can gain a better understanding of the nature and characterization of the aquifer.”

BWS previously tested the well in 2015 following an estimated 27,000 fuel leak at Red Hill, and it did not contain any PAH, Kawata said. But he took a sample in May, and it came back with detection levels similar to those under the Red Hill facility, he said. Given that the well is in a residential area, Kawata said it’s unlikely the chemicals came from anywhere but Red Hill. 

Going forward, the utility will test wells every three months to collect more data and look for trends.

The levels detected are low, in the parts per trillion, but they are a concern because their “rigid chemical structure” means they don’t break down easily in the environment, according to Kawata. 

BWS regularly tests its drinking water wells for PAH and hasn’t previously seen any detections, Kawata said.

Kawata said the detection is further evidence that fuel needs to be removed from the Red Hill tanks as soon as possible. The Red Hill facility – including 20 massive tanks and miles of pipeline – still holds approximately 100 million gallons of fuel just 100 feet above Oahu’s primary drinking water aquifer.

The Pentagon said it would close the facility after last year’s contamination crisis that affected some 93,000 people on the Navy’s drinking water system.

The Navy submitted a defueling plan to the Hawaii Department of Health, but DOH recently rejected it for lacking specificity. An updated plan is due to DOH next month.

The PAH detections also suggest the Navy should work to drill monitoring wells on the east side of the Red Hill tanks, Kawata said. BWS will be installing its own too, he said.

“These monitor wells are really meant to look at the presence of any contamination well beyond the Red Hill property and help answer some of the questions about the implications for the aquifer,” Kawata said.