The Navy has notified the state Health Department that Tank 5 at Red Hill, which experienced a 27,000-gallon jet fuel leak in 2014, is being brought back into service, the U.S. Environmental Protection Agency said today.

Since 2014, Tank 5 has remained out of service, but has “undergone extensive evaluation, repairs, and testing,” the EPA said in a news release. “The Navy has made significant changes to their inspection, repair, and quality control processes as well as improved their approach to quality assurance of their contractor’s work.”

The EPA said in contrast to the filling process in 2014, Tank 5 “is being filled very slowly, with numerous points throughout the process where filling is stopped, and testing for leaks is performed.”

“The Navy is prepared for emergency draining of the tank if a leak is identified by having adequate empty capacity available in other tanks. This is in sharp contrast to the events of 2014 when the tank was filled rapidly with limited testing and the inability to address leaks quickly,” the federal agency said.

EPA and the Hawaii Department of Health are monitoring the process of bringing Tank 5 back into service at the Red Hill Bulk Fuel Storage Facility “in order to prevent repeat of mistakes made in 2014,” the EPA said.

The tank re-use notice came from the Navy and Defense Logistics Agency.

An “administrative order on consent” was entered into by the Navy, Defense Logistics Agency, EPA and state Health Department to make improvements after the 2014 fuel spill from the World War II-built tank farm.

Much of the concern over Red Hill centers on the tanks’ location 100 feet above a water supply aquifer, which is in saturated volcanic rock. Each tank can hold 12.5 million gallons of fuel.

The Southern Oahu Basal Aquifer, which lies below Red Hill’s 20 giant underground fuel tanks, is the principal source of drinking water for more than 750,000 Oahu residents.

The Navy thinks deep claylike barriers to any leaked fuel extend through the aquifer in valleys separating the Board of Water Supply’s Halawa and Moanalua water shafts from Red Hill.

The Board of Water Supply, however, said some groundwater modeling shows a flow gradient across the valley toward the Halawa water shaft.

The Navy proposed a deadline of 2045 to provide what it calls “double-wall equivalency secondary containment,” or, in the alternative, removal of the fuel if that is not possible.