A Navy contractor prepares a granular activated carbon filtration system to begin cleaning water pumped from the Red Hill well in Aiea, Hawaii, in January 2022. (Christopher Thomas/U.S. Navy)
FORT SHAFTER, Hawaii — University researchers are using a florescent dye in the aquifer near Pearl Harbor to better understand the flow of water beneath the Red Hill Bulk Fuel Storage Facility, site of a massive jet fuel spill three years ago.
Over six days in mid-February, researchers injected 50 pounds of rhodamine dye, mixed with 5,000 gallons of water, into a well shaft operated by the Navy, Toomas Parratt, a researcher at the University of Hawaii’s School of Ocean and Earth Science and Technology, said by phone Feb. 24.
The injection point was about a quarter mile upgradient of the Navy’s Red Hill well, which was contaminated with jet fuel in late 2021 from a spill at the fuel storage facility. The facility was subsequently closed.
The aquifer’s flow in that area is not fully understood, and the researchers hypothesize that the underground water will primarily flow toward the Red Hill well rather than to wells in other directions.
The Red Hill well, one of three used by the Navy for its water distribution system in supplying more than 90,000 households in military communities on and near Joint Base Pearl Harbor-Hickam, was isolated from the system in the wake of the contamination.
In January 2022, the Navy installed a series of massive carbon filters at the Red Hill well site.
Each day, millions of gallons of tainted water are pumped up, filtered and released into the nearby Halawa Stream. The continuous pumping is intended to prevent petroleum contamination in the well from migrating elsewhere.
Parratt said he expects most, if not all, of the nontoxic dye will end up at the Red Hill well and be absorbed by the carbon filters.
Parratt conducted initial testing using a device called a colloidal borescope, which is lowered into well sites to gauge the direction and velocity of groundwater.
He said he found “a real strong connection” of flow from the Navy well shaft designated RHMW08, which is the injection site, and the Red Hill well.
Understanding movement in the aquifer is important as the Navy Closure Task Force-Red Hill works to empty and clean the Red Hill fuel facility, which was ordered permanently closed by Defense Secretary Lloyd Austin in March 2022.
The task force is also charged with the years-long clean-up of the soil and groundwater contaminated by fuel.
“Understanding the flow patterns of groundwater in the subsurface is important to assess the environment in the Red Hill area and investigate contamination around and underneath the facility,” the U.S. Environmental Protection Agency states on its web site.
The task force said in an emailed statement Wednesday that it would incorporate the published findings of the dye study with the groundwater flow model the Navy submitted in September to the U.S. Environmental Protection Agency.
The university researchers are monitoring the dye in real time in two ways.
First, LED lights are lowered into monitor wells to take hourly readings that gauge the amount of fluorescence. This is useful in understanding the timing of the dye’s transport from the injection site.
Second, carbon packs that absorb dye are inserted in other wells. Those packs are removed, crushed up and analyzed. These will indicate whether water from the injection site flows to a particular site.
The light and carbon readings can subsequently be used in a groundwater model that simulates different amounts of flow to see which one best matches the plume spread from the dye experiment.
“The idea is that we try to calibrate the groundwater model that matched the spreading of the plume that was observed,” he said.
Readings at the Red Hill well are taken every 10 minutes and will provide an estimate of the velocity of groundwater.
Those readings will also be used to extrapolate how much of the 50 pounds of dye ended up at the Red Hill well, Parratt said.
The dye is expected to reach the Red Hill well by early spring, with preliminary findings likely released in early summer, he said.
