Construction Completed on Drive-in Submarine Magnetic Silencing Facility

Story Number: NNS110120-03Release Date: 1/20/2011 5:33:00 AM
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By Thomas Obungen, Naval Facilities Engineering Command Hawaii Public Affairs

PEARL HARBOR (NNS) -- Naval Facilities Engineering Command (NAVFAC) Hawaii wrapped up construction for a new drive-in submarine magnetic silencing facility (MSF) Dec. 31, 2010, at Joint Base Pearl Harbor-Hickam's Beckoning Point.

NAVFAC Hawaii administered the complex project that involved different Navy commands and coordinated the construction of the new facility with Honolulu-based Watts-Healy Tibbitts Joint Venture.

"The construction of this important submarine complex was multifaceted and required significant coordination," said Dennis Djou, NAVFAC Hawaii construction manager. "The water and land-based structures, special material requirements and specific technical considerations all contributed to the intricate nature of this effort."

NAVFAC Pacific awarded an $84.8 million contract in August 2008 to replace the original submarine deperming piers and structures at Pearl Harbor with a modernized drive-in MSF modeled after one at King's Bay Naval Submarine Base, Ga.

NAVFAC Hawaii commenced work on the project in November 2008 with pile-driving tests to assist in pile design to be used in the new pier. Once testing was completed, demolition of the existing wharf and old magnetic silencing facility got underway. Simultaneously, construction of the new the shore-side facilities broke ground.

In January 2009, the contractor began dredging operations for the new pier location and approach area so the new facility would be able to accommodate the Navy's larger Virginia-class submarines.

At the same time, 173 permanent piles and other precast concrete items were fabricated on Guam (with a special coral-based, non-magnetic concrete aggregate used) and then shipped to Hawaii.

The piles for the facility's piers were installed during a nine month period starting in November 2009, with a concrete deck laid over them. One small access pier and one set of 700 foot-long parallel finger piers were constructed.

In addition to the special non-magnetic piles, other non-traditional materials like stainless steel rebar, aluminum superstructure and underwater titanium fasteners and bolts were also used for their anti-magnetic and non-corrosive properties in the construction of this project.

Construction on the facility's land-based buildings, such as a new rectifier (a power conversion) building, back-up generator building, and renovations to the complex's control building, also got underway at this time with work continuing throughout the project's two-year time frame.

The final stage of the project's construction was initiated in October 2010 with the installation of 18 trusses that straddle the parallel finger piers. These trusses will hold the silencing facility's above water portion of the high voltage cables that will run perpendicular along the length of the submarine to be treated.

To further protect the integrity of the new silencing facility, magnetic anomaly surveys and removals were conducted to ensure no other substances in the water or on the harbor floor would affect the facility once in service.

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