The Navy is weighing six options for ramping up safety at large underground aviation fuel tanks near Pearl Harbor, federal and state officials said in a report issued Monday.

To comply with an agreement reached with the Environmental Protection Agency and the state Department of Health, the Navy is required to make improvements to its Red Hill Bulk Fuel Storage Facility in the wake of the release of 27,000 gallons of fuel from Tank 5 in January 2014. Samples from nearby water-monitoring wells indicated a spike in hydrocarbons.

The incident touched off community outcry about the potential for the contamination of Oahu’s groundwater supply. While testing shows drinking water sources nearest the Red Hill tanks to be free of petroleum contamination, city water officials worry the fuel could eventually migrate into the city’s water wells.

Navy officials maintain that the facility’s 20 World War II-era tanks — each capable to holding 12.5 million gallons — are vital to operations at Pearl Harbor. The tanks supply fuel to Navy ships and aircraft as well as to other military services.

Three of the half-dozen proposed safety upgrades involve installing a double-wall containment system around at least some of the tanks, according to a report issued Monday by the Health Department and the EPA. The extra layer is favored by Honolulu water officials and others pointing to two Navy studies, the latest completed in 2008, that recommend it.

One of the double-wall proposals involves placing a new tank inside an existing tank, the report said. The two others call for constructing “a double- walled tank, without an accessible outer wall, using regular steel or stainless steel.”

The options now under consideration were selected from 14 tank-upgrade proposals that were evaluated in a January preliminary study conducted by Maine-based Enterprise Engineering Inc. The Navy winnowed the number to the current six proposals and will make a decision and present it to the Health Department and the EPA to see whether they agree.

In the report, Erwin Kawata, the Honolulu Board of Water Supply’s water quality division program administrator, said his agency is still reviewing the options for preventing and detecting leaks.

The report also said the Navy has reached agreement with the EPA and the Health Department on four new groundwater monitoring wells that will be installed north, west and south of the Red Hill facility beginning this year.

There are currently 10 monitoring locations, three of them directly under the tanks, which are fitted with a single-wall containment system.

Before well drilling gets underway, Navy officials plan to examine the area’s geology and groundwater flow in an effort to determine whether any liquid fuel is under or adjacent to the tanks.

“While some may believe the Navy should immediately begin drilling to find and remove fuel, without a better understanding of the area’s complex geology, an unintended consequence may be the creation of pathways that speed the flow of contaminants into the groundwater,” the report said.

In addition, the report said the Navy is developing new technical specifications for tank inspection and repair operations, and changing its contracting procedures to improve management of construction quality.

To access the status update, as well as links to the EPA and Health Department websites devoted to the Red Hill situation, go to bit.ly/ EPARedHill0316update.