UCT 2 Reopens Deep-Draft Wharf

BRITISH INDIAN OCEAN TERRITORY

12.20.2016

Courtesy Story

Underwater Construction Team 2

Underwater Construction Team (UCT) 2’s Construction Dive Detachment Bravo (CDDB) completed maintenance and light demolition to clear a deep-draft wharf in Diego Garcia, reopening the wharf for use to the fleet in Dec. 2016.

The wharf had become fouled with a large concrete fender panel that had deteriorated and fallen to the bottom, blocking all traffic adjacent to the pier. To reopen the wharf, CDDB removed two 57-ton concrete fenders as well as four 20-ton support piles alongside. In doing so the team quickly and cost effectively reestablish one third of Diego Garcia’s ship to shore capacity ensuring maximum operational capability for this location.

The four concrete piles were encased by a jacket of 3/8” mild steel and rose 50 feet out of the sea floor. The first two piles were removed using exothermic torches burning the steel at 10,000°F and hydraulic jackhammers to finish breaking apart the concrete contained within. The piles were then rigged with slings and pulled out of the water and placed onto cargo trucks by a crane.

“I wasn’t really sure what to expect when it came to my first deployment with the team,” said Construction Mechanic 3rd Class Lucas Jackson. “We’ve used pretty much every piece of equipment I learned about in dive school along with demolition.”

The second set of piles brought an entirely different challenge to the dive team. Because they stood vertically in the water column, it was not possible to safely cut them with divers in the water. CDDB selected the safest course of action and used precision demolition to break them up. The demolition required an explosion strong enough to cut through 18 inches of steel and concrete, but not damage the wharf and surrounding marine life. After hours of planning and conducting test shots on land, the team was able to fabricate a shape charge that could cut through the pile with the least amount of explosive required. Divers then placed tires around the charge to absorb the shock wave and employed a bubble screen to reduce the noise levels on marine life in the surrounding area.

“It’s been a while since the team was actually able to plan and execute an underwater demolition mission like this,” said Builder 1st Class Christopher Chilton. “These types of jobs are few and far between, but when the team is able to exercise this capability, we try to expose everyone to as much of the process as possible for a deeper understanding for future operations.”

Lastly, the team removed two 57-ton concrete fender panels, descending into the water once again to remove enough mud and silt from underneath the fender in order to slide 100-ton lifting slings underneath. Multiple dives were required to properly rig the slings to the hoisting chains. The Merchant Vessel Ocean Crescent assisted with their ship-based crane to pluck the first massive concrete structure out of the water and place it on the wharf.

For the second fender the divers rigged two 70-ton pontoon style lift bags which measured over eight feet in diameter and over 15 feet in length. Each lift bag was rigged to the fender and then inflated using compressors to bring the fender off of the sea floor. Once the lift bags hit the surface, there was much to do in a short amount of time. A support craft hooked into the tow line to drag the fender a third of a mile to deeper water. All the while, personnel had to keep air flowing into the lift bags due to a faulty relief valve bleeding out air. When the fender was over its final resting place, all the team had to do was stop air flow into the lift bags and the concrete slowly made its descent in a safe and controlled fashion.

“I’m extremely proud of the guys here,” said Chief Construction Electrician Daniel Luberto. “I couldn’t ask for a more hard-working, determined, and focused group. They not only showed the capabilities of a UCT Diving Detachment, but also showed how they can exercise these capabilities anywhere on the globe. For that, I cannot express how proud I am about what these guys accomplished while they were out here.”

Diego Garcia was the last stop in CDDB’s six month deployment across the Pacific. The detachment stopped previously in Kauai and Kwajalein to perform maintenance, inspection, and repair of underwater and near-shore facilities.

Underwater Construction Teams provide a capability for construction, inspection, repair, and maintenance of ocean facilities in support of Navy and Marine Corps operations including the repair of battle damage. The teams have the capability to support a Fleet Marine Force (FMF) amphibious assault, subsequent combat service support ashore, self-defense for their camp and facilities under construction, and conduct emergency/disaster control and recovery operations.

• Date Taken: 12.20.2016
• Date Posted: 02.24.2017 17:09
• Story ID: 224862
• Location: IO