Naval Station Everett.
Naval Station Everett is improving equipment used to serve its five homeported U.S. Navy destroyers when they are in port. While existing facilities are capable of keeping pace with requirements, a recent pilot project is expected to make the processing of seawater after ship refueling more time and cost efficient.
NSE is currently home to the Arleigh Burke-class guided missile destroyers USS Momsen, USS Gridley, USS Kidd, USS Sampson, and USS Ralph Johnson. The ships use seawater for ballast that helps them remain stable in the water. As the fuel in their tanks are gradually used up, seawater is added to maintain even weight distribution.
When ships refuel in port, the seawater is displaced by incoming Diesel Fuel Marine (DFM). As seawater is flushed out of the fuel tanks, it is collected and treated according to environmental regulations prior to disposal.
Previously, the base had used a facility that was mainly designed to treat bilge water from ship sewage that took nearly two weeks.
In order to speed up the process, NSE collaborated with Naval Facilities Engineering and Expeditionary Warfare Center (NAVFAC EXWC) to develop new equipment that would treat the mixed seawater separately. The collaboration
led to the first generation development of a Compensating Water Management Unit (CMU) in 2002, and then a second generation system for practical use. NSE became the first Navy shore installation to test the pilot system last
year.
The CMU device is housed in a shipping container that is placed near a barge that collects the seawater during refueling. As mixed seawater from the barge is pumped directly into the CMU, a funnel shaped hydrocyclone spins
and separates the small amount of oil and fuel. The water also goes through a large filter that absorbs zinc, heavy metals, and other matter. The water is sampled and analyzed for the presence of any remaining contaminants to confirm that it meets permit requirements before being discharged to the sewer system.
To ensure environmental compliance, the Navy worked with the City of Everett and the Washington State Department of Ecology while completing the permitting process.
Base Public Works Utility Energy Manager, Ray Smalling, said “We sample and test processed water regularly to ensure that discharge to the city sewer system is well below the limit of four milligrams per liter of zinc as required by permit, to support state and local wastewater discharge requirements and environmental protection laws.”
In January, NSE began putting the CMU to the test. A complete return on the cost of procurement is expected in a year. One CMU is capable of processing 250,000 gallons of mixed seawater from a collection barge within two work days, compared to the seven workdays typically required by the larger treatment facility. Additionally, the CMU was designed to reduce the cost of treatment per gallon by more than 50 percent. Its use may help save the Navy on significant processing costs in future years.
The CMU pilot project demonstrates NSE’s long standing commitment to innovation, efficiency, and environmental stewardship. Protection for the environment in which ships and service members train is essential to continuing maritime operations and national security.
April 16, 2019
Everett