The Navy agreed it needs to do more to evaluate fuel and water flow modeling beneath and around the Red Hill fuel storage facility before a Dec. 8 deadline for a finalized fuel tank upgrade plan.

The U.S. Environmental Protection Agency and state Department of Health sent a June 7 letter criticizing the Navy for providing too little information on water flow modeling to determine where previously spilled fuel might end up, even though the Navy has spent almost two years on the environmental investigation.

The Red Hill Bulk Fuel Storage Facility continues to be a contentious issue as the Defense Department, EPA and state Health Department work through a long-term plan for the facility’s future.

An open house with experts from the Navy and regulatory agencies drew hundreds of people Thursday at Moanalua Middle School, and about a dozen protesters who carried signs with language including “Protect Our Water.”

The water and fuel flow modeling review is part of an administrative order on consent entered into to minimize the threat of fuel releases following a 27,000-gallon spill in 2014 and periodic spills before that at the World War II-era facility.

The facility consists of 20 12.5-million-gallon underground fuel storage tanks that are each 250 feet tall.

The regulatory agencies said “there are abundant data currently available and easily obtainable (regarding water flow modeling) that the Navy should have already collected and analyzed.”

In a June 20 letter to Red Hill “stakeholders,” Rear Adm. John Fuller, head of Navy Region Hawaii, said, “We can and we will do better. While no one likes getting a progress report that essentially says, ‘Navy, you need to work harder and smarter to meet a future requirement,’ their letter illustrates the (consent order’s) power and value. It proves that the process is transparent and working.”

The Navy already has taken steps “to bring onboard additional consultants who have the exact expertise we need, and we have officially requested relevant data from any organization that can help,” Fuller said.

A better understanding of groundwater flow patterns is a critical step in the investigation of contamination at Red Hill, the EPA said on its website.

“While most parties agree that groundwater generally flows from the mountains to the ocean, there are specific geologic characteristics in the area around Red Hill that may cause some groundwater to flow in directions other than directly towards the ocean,” the EPA said.

Specifically of concern is the Board of Water Supply’s Halawa water shaft, which is more than a mile away on the other side of the H-3 freeway.

Beneath Red Hill’s 20 feet of concrete is intermixed lava rock that in some cases is as hard as concrete and in other areas more like cinder blocks, experts said.

The aquifer is about 100 feet beneath the Red Hill tanks held in water-saturated rock and soil, said EPA and Health Department consultant Ron Chinn.

“The question is whether the (spilled) fuel can make it to the Halawa shaft,” Chinn said. “In order for it to do so, it needs to cross two valleys, which is kind of difficult to do.”

The Navy is looking at six alternatives for the steel-lined, concrete-enshrouded tanks, including restoration of the tanks with enhanced inspection, repair and maintenance; restoration plus interior coating; replacement of the steel liners; composite double-walled tanks with carbon steel; composite double-walled tanks with stainless steel; and a tank within a tank using carbon steel.

Also required by the consent order is a study of alternate sites for fuel storage, with a target due date of late this year, but the Navy said its desire is to continue using Red Hill.