The familiar pitter-patter of rain strikes the pier on this steel-grey Seattle morning as white-capped waves break upon the wood pylons of the structure.
Even in the dead of winter, the salt-licked air around Terminal 91 hums with activity. The giant fish processors of the Bering Sea fleets have left their berths for the frigid waters up north. The cruise line industry has yet to arrive to begin its season of vacation runs to Alaska.

Beneath the choppy Puget Sound waters linger remnants of a bygone war that could potentially harm both life and this robust sea-faring industry.
In April 2010, during a routine security dive, Port of Seattle police divers discovered munitions that date back decades to when the facility was used by the U.S. Navy. The U.S. Coast Guard (USCG) was immediately called, as was the U.S. Navy Explosives Ordnance Disposal Unit, which removed the munitions.
Port of Seattle police continued to perform the routine dives throughout the summer. The World War II-era munitions were found on six more occasions, the last of which was considered hazardous. Consequently, the USCG issued a Captain of the Port Order restricting vessel operations until further information was collected - potentially impacting the 2011 cruise season.

To stem the threat beneath the tide, a unified command group of federal, state and local agencies, led by the U.S. Army Corps of Engineers (Kansas City, Omaha and Seattle districts) launched a underwater munitions response.
"The extensive and successful collaboration between the three Corps districts, Port of Seattle, U.S. Coast Guard, U.S. Navy and Environmental Protection Agency made this project successful," said Pam Kromholtz, Seattle District's project manager.

"From our initial involvement in late September 2010, everyone has worked diligently and innovatively to assure successful and timely completion of the mission," said David Nelson, Kansas City District team leader for the FUDS program. The safety of the public is a top priority. "We consider the dock worker. We consider the people in the fishing boats. We consider the people on the cruise liners," said Jerry Hodgson, the manager for the Omaha District's Military Munitions Design Center.

Beyond safety is the economic impact of the terminal. Terminal 91 consists of Pier 90 and 91. In 2009, the outermost portion of Pier 91 was retrofitted to service up to two cruise liners at a single time. Last year, alone, the cruise industry brought in $425 million to the area.

"It's a huge economic engine for the Puget Sound region," said Peter McGraw, media officer for the Port of Seattle. "It's responsible for more than 4,400 jobs."
The project team also considered the environmental impacts. "Terminal 91 is located 10 miles north of downtown Seattle, and in the heart of the Puget Sound, which is the nation's second largest estuary," Kromholtz said. "Environmental impacts were studied to ensure activities were consistent with environmental regulations and the Puget Sound Cleanup Initiative. This area has a sensitive ecosystem and as such sonar impacts on marine mammals, spawning fish windows for listed and endangered species, and other environmental concerns were studied.

In addition, cultural and natural resources and tribal usual and accustomed fishing areas were coordinated and investigated. Each one of these environmental considerations had the potential to greatly impact project timing and success," she said.

With the cruise industry set to start back up in mid-April, the window to reduce the potential risk was tight. The U.S. Army Corps of Engineers authorized a time critical removal action to deal with munitions found in the areas where cruise ships berthed on Pier 91 and the waters some 400 yards beyond the pier heading into the harbor.

"A time critical removal action is an action in which you have less than six months of planning time in order to accomplish a project - and if you don't accomplish that project, there's a threat to human health and the environment," Hodgson said.
The time critical removal action was funded through the FUDS Program with support from the Corps Northwestern Division and Headquarters offices as well as the Department of Army. Under the FUDS program, the Corps inspects, evaluates, manages and executes required cleanup of contamination caused by the Department of Defense at eligible properties owned and controlled by DoD prior to October 1986.

In the 1940s, the United States was fighting a world war in two distinct oceanic theaters. Battle-ridden naval vessels used the then four piers here to restock goods from the adjacent Naval Supply Depot. At least one World War II veteran told port authorities that sailors were instructed to jettison spent rounds, casings and unneeded supplies and munitions overboard as they approached the piers to expedite the resupplying process. Those munitions have lain on the seabed since that time. The suspicion is the powerful bow thrusters from cruise ships may have blown layers of silt away from the bottom, exposing the shells. "The biggest threat is an unintentional detonation - somebody, something, somehow interacting with a munition down there that causes it to detonate," Hodgson said. But the level of that threat was a big question mark.

"Coming into this, the risk was pretty much unknown," Hodgson said. "To date, everything we've found is called discarded military munitions and not an unexploded ordnance." The difference between the two is critical.
Unexploded ordnance is a projectile, bomb or other explosive device that has been primed and/or fired but didn't function properly.
The sensitivity of such an item is high, and its risk is unknown, unless you're an explosive ordnance disposal specialist trained in such matters.
Discarded military munitions are simply that - a projectile, bomb or other explosive device that has been dropped or left behind.

It hasn't been fused or fired.
Discarded military munitions might still have an explosive in them, but they would require some type of substantial interaction such as heat, friction or shock - or a combination thereof - to go off.

"You don't want to say they're not dangerous," Hodgson said. "But on a scale, they are more benign than unexploded ordnance."

A third type of munitions litters the site as well - military munitions debris. This debris is the spent casings of shells already fired and poses no threat to human safety.

After developing a draft plan and coordinating it with the unified commanders, the Corps awarded task orders to Sky Research. Hodgson and his team worked with Sky Research to further break down the situation at Terminal 91.
"We knew so very little coming in with such a tight schedule, although we had a plan developed, each phase of that plan was developed on what we found out in the first phase," Hodgson said.

To establish a baseline of conditions at the pier, the team began a series of reconnaissance dives and research into existing literature on the area. For the dives, Land Air & Sea Explosives Ordnance Disposal (LASEOD) was brought on board.

Mike Dehoyos, the senior dive supervisor for LASEOD, took the first dive with a dive partner Dec. 14, 2010. While pleased with the visibility on the bottom, he noticed a common threat to divers.

"Like any pier area that I've swam or dealt with, there's just a lot of debris there that's typically thrown off ships that are tied pier side," Dehoyos said.
That debris would play a large role in factoring what technologies would be selected and used on the site.

Following the initial reconnaissance dives, Sky Research began a series of data collection using multi-beam and side scan sonar to map the bathymetry, or the topographical features of the sea bottom and corresponding water depth.
Later, Sky Research used stationary scanning sonar to produce an even higher resolution picture. The main difference between the two is that stationary scanning is performed on a tripod placed on the surface bottom, whereas the side scan is done with an array dragged through the water by a boat.

With that work done, a marine magnetometer array was deployed over the site to provide a map of the surface and subsurface distribution of ferrous metal anomalies, which could be military munitions related.

"Based on the sonar, dive reconnaissance and geophysics, we determined much of the site was littered heavily with debris, both metal and non-metal," said Jack Foley, vice president of technology for Sky Research.

With all the debris, the team determined that they needed to have a two-pronged approach - divers and remotely operated vehicles both scanning the entire area.
"The ROVs gave us the ability to say there's something here or we didn't see anything, let's look at a different area," said Ronald Hetzel, the senior unexploded ordnance supervisor for Sky Research on the site. "It allows us to concentrate our efforts as this is a time critical response action."

Both ROVs and the divers used GPS data to document every trip into the depths and pinpoint every location where discarded military munitions and munitions-related items were found. Additionally, the sites were flagged.
The surveys uncovered 11 discarded military munitions and 212 munitions-related items.

LASEOD divers returned to all of the items and brought them back to the pier March 30. From there, the Joint Base Lewis-McChord Explosive Ordnance Disposal unit took physical control of the munitions and transferred them to the base for disposal.

"Our goal was to complete the time critical removal action field work by April 15," Kromholtz said. "On account of excellent team work and dedication, we were able to beat the schedule and complete the field work March 30."

Based on the results, the U.S. Coast Guard modified its Captain of the Port Order allowing the cruise season to begin without interruption. The Port of Seattle will continue performing its routine security dives.

"The Corps developed an emergency response process for the Port of Seattle in the event more munitions are found so that the items will be safely removed and destroyed," Kromholtz said.

The work is not yet done. Additional dives and surveys remain for the areas around Pier 91 and the adjacent Pier 90.