In the days after approximately 1,000 gallons of jet fuel leaked from a pipe at the Navy’s Red Hill underground fuel farm on May 6, soil vapor levels indicating fuel contamination spiked well above averages, according to data released by the Hawaii Department of Health on Monday. The elevated soil vapor levels are raising concerns that not all of the leaked fuel was recovered, as the Navy has suggested.

Indeed, Health Department officials said last week that the soil vapor data, which at the time they were declining to release publicly, indicated fuel had entered the subsurface.

“The Navy’s claim is pure shibai,” said Hawaii Sierra Club attorney David Kimo Frankel in a press release on the soil vapor data. “The Navy’s own data proves that its leak was not properly contained. The leak migrated from the facility and reached the subsurface. The Navy cannot be trusted with our groundwater.”

In response, a Navy spokeswoman said that the soil vapor data is likely inaccurate and is “undergoing validation.”

The Navy uses the soil vapor monitoring system to detect possible fuel leaks. The data released by the Health Department on Monday shows petroleum vapors below seven of the tanks in the vicinity of the spill ranged from 170 parts per billion by volume (ppbv) to 1,184 ppbv in late April. Readings taken in the days after the spill show levels far above that around many of the tanks. Vapor levels reached a high of 232,667 ppbv below one of the tanks – a level that is more than 1,000 times its average prior to the spill.

Missing from the data are soil vapor readings in the days immediately following the May 6 fuel leak. Readings aren’t listed for some of the tanks until May 10. For tanks 17, 18 and 20, the tanks closest to the leak, soil vapor data isn’t listed until May 13, a week after the spill.

The readings are recorded by the Navy and provided to the Health Department, which along with the U.S. Environmental Protection Agency, regulates the facility.

The Navy said that cleanup procedures following the leak prevented its contractor from immediately taking readings and that it believes the elevated readings in later days were due to contamination.

The monitoring tubes “were likely contaminated by water washdown and cleanup performed after the release,” Navy spokeswoman Lydia Robertson said by email. “The tubes needed to be cleaned of debris and soil, and we believe the elevated numbers are due to sampling port contamination during fuel cleanup.”

The Red Hill facility, which contains 20 underground fuel tanks, each big enough to envelop Aloha Tower in downtown Honolulu, has been the subject of ongoing concerns from the public, regulators and environmentalists since the Navy reported that 27,000 gallons of fuel leaked from one of its tanks in 2014. Subsequent reporting, based on the Navy’s own documents, revealed that there have been dozens of leaks at the aging World War II-era facility. The Honolulu Board of Water Supply, whose mission is to keep Oahu’s drinking water safe, has raised alarms that leaks from the facility, which sits over an aquifer, threatens a major source of drinking water for the island.

This latest leak has energized calls for the Navy to relocate the facility.

“This latest data demonstrates that the Navy is unable to deliver on its promises to protect our water from their fuel,” said Hawaii Sierra Club Director Marti Townsend in a press release. “Any amount of fuel leaked into the environment is too much—especially when it is so close to our drinking water. There is only one reasonable course of action: immediately retire the decaying Red Hill facility and relocate the fuel to modern tanks far away from our drinking water supply. Continuing as we are now is absolutely insane.”

Robertson said that the Navy is “committed to a thorough and accurate investigation,” of the spill and is working with regulators to comply with additional testing and reporting requirements.

She reiterated prior statements by the Navy that the “containment system at Red Hill’s lower tunnel worked as intended to capture fuel from the release.”