Navy concludes investigation on water contamination about USS Nimitz

The Navy has concluded its investigation into potable water contamination aboard the USS Nimitz in September 2022.

The Navy said in the results, released this month, that a jet fuel leak happened when the ship was deployed between June 2020 and March 2021.

In March 2022, Puget Sound Naval Shipyard cleaned one of the ship's eight potable water tanks that were out of service and suspected to be contaminated with seawater. Due to resource availability and the duration of the in-port period, the shipyard didn't finish cleaning others. The ship developed a procedure to clean some additional water tanks while at sea and then that led to the ship's potable water being contaminated with jet propellant-5 (JP-5) on Sept. 16, 2022.

During the ship's previous deployment between June 2020 and March 2021, the JP-5 jet fuel in the ship's bilges leaked into an unused potable water tank through a deteriorated manway cover gasket on top of the tank, the Navy said.

"JP-5 was likely introduced into the bilge in space during the ship's last deployment due to misalignment or malfunction of the ship's main drainage system," the report said.

The ship's crew was unaware of the presence of JP-5 in a potable water tank prior to Sept. 16, 2022, the report said.

The Nimitz's 2020-2021 deployment was the Navy's first such launch of a carrier strike group in the COVID-19 global pandemic, in which the ship sailed through the South China Sea and the Middle East.

The investigation document said that in February 2022, a reactor officer discovered that 8 of the ship's 26 potable water tanks were out of service and not used to supply the ship with potable water. Caution tags were hung on the suction and fill valves, and the officer directed Reactor Propulsion Division to make plans to clean, inspect, and restore the tanks to service before Nimitz's upcoming deployment.

During an in-port period in March 2022, the ship requested Puget Sound Naval Shipyard to help empty and clean the potable water tanks that were out of service. The tanks were suspected to be contaminated by seawater, the report said.

"PSNS assisted the ship with emptying tank. However, PSNS was unable to accomplish additional tanks due to resource availability and duration of the in port period," the report said.

The shipyard used a temporary system to pump the liquid out of the tank through an open manway access cover. The report said workers cleaned, inspected, sanitized, and restored the tank to service.

"Based on upcoming operational demands that warranted recovering full potable water storage volume, the ship developed a sequencing document with procedures to empty tanks utilizing the ship's installed potable water pumps rather than waiting for shipyard assistance at future in port period or opening the tank manwaycovers and emptying the tanks utilizing a temporary pump and hoses," the report said.

It is noted in the report that the ship's forces do have the capability to isolate and empty potable water tanks using a temporary pump and hoses through an open tank top manway, but the process is time-consuming and can be difficult to do when the ship is at sea, according to the report.

Homeported in Bremerton, the Nimitz was heading out for sea trials and training off the coast of San Diego between Feb. 7, 2022 and March 26, 2022.

More:USS Nimitz comes home to Bremerton, following 2 months of training at sea

The sequencing document has procedures to empty the tanks by pumping the contents overboard via a hose connected to the potable water system utilizing the ship's installed potable water piping and pumps, the report said.

By Sept. 15, 2022, the division used the sequencing document to empty four additional potable water tanks.

On Sept. 16, 2022, the Reactor Propulsion Leading Chief Petty Officer directed the Chief Machinery Operator (CMO) to empty a potable water tank using the sequencing document. That day, JP-5 was spread to the ship's potable water distribution system during the procedure.

"The sequencing document the ship developed to empty potable water tanks containing water of unknown purity did not comply with the intent of the governing manuals, reference (b), (c),and (d), for maintaining the potable water system clean and free of contaminants," the report said. "Additionally, the sequencing document did not contain enough detail to ensure operators flushed all affected potable water piping, nor did it contained provisions for verifying the effectiveness of the flush or system cleanliness prior to using the system to supply potable water to the ship."

More:Jet fuel contaminates water supply aboard USS Nimitz before deployment

Sailors reported a fuel-like smell and taste in the ship's potable water. At that time, the Nimitz was operating off the coast of Southern California. Engineering personnel secured access to the potable water and tested the tanks while free bottled water was given to the crew.

Eleven sailors reported symptoms that may have been a result of ingesting the jet fuel, the Navy said.

From Sept. 17 to Oct. 2, 2022, the ship was docked in port at Naval Air Station North Island in San Diego. During that time, Nimitz was connected to City of San Diego water supply and continued to provide fresh water to the crew.

Test results on Oct. 1 showed that 22 of 26 potable water tanks tested below the health action level for JP-5 in drinking water recommended by the Navy and Marine Corps Public Health Center, the report said. And the ship's potable water was determined to be safe, according to the Navy.

More:Nimitz still docked in San Diego as ship's water supply still contaminated with jet fuel

Nimitz departed San Diego on Oct. 2, returned to Bremerton on Oct. 28, and the isolated tanks were cleaned, repaired, inspected and returned to service, said the Navy.

"Currently, all 26 potable water tanks on board are providing safe water to the crew," the Navy said.