Naval Submarine Base New London (SUBASE) recently completed its scheduled comprehensive, maintenance dredging project, 11 days ahead of schedule and more than two million dollars under budget.
GROTON, Conn. – Naval Submarine Base New London (SUBASE) recently completed its scheduled comprehensive, maintenance dredging project, 11 days ahead of schedule and more than two million dollars under budget.
The project entailed removing more than 97,000 cubic yards of Thames River sediment from the areas around each of SUBASE’s piers and quay walls.
Performed by Great Lakes Dredge and Dock, the effort brought down the berthing depth of the piers at SUBASE to the original design depth of 36 feet, plus two feet over-dredge.
“Considering the maximum nature of the dredging project, across the scope of the entire SUBASE waterfront, we were very happy to have minimal impact on our submarines,” said Lt. Richard Thomas, base Port Services Officer. “I think our coordinated team approach really made the difference.”
The team consisted of the base Port Services Department, Public Works Department (PWD), and it’s Environmental Division.
The original project plans estimated 170,000 cubic yards of sediment to be removed at a cost of 9.5 million dollars.
As less dredging was necessary than originally anticipated, when the dredging was complete, the actual cost was slightly over seven million dollars.
Time was also a critical component of the project.
The dredging was on a specific schedule due to an environmental window which ran from the First of October to the Fifteenth of February this year, limiting potential impact to marine wildlife.
“There is a specific timeframe in which we must complete the dredging called the ‘environmental window’,” explained PWD Project engineer, Stephen Meagher. “This window, set by the Corp of Engineers and EPA, allows us to only dredge the river during winter months when the finfish are not spawning.”
Time was further impacted by delays due to weather, permits, and dredge spoil disposal issues.
Dredging did not begin until December 27, 10 days behind schedule.
The dredge spoils disposal site for the dredged sediment was 41 miles away at the New Haven disposal site, and the State of Connecticut allowed SUBASE to pass the normal January 31 deadline for dredging and schedule a February 15 completion date.
“Even with all the delays, the project only ran four days past the normal deadline for dredging,” noted Meagher.
The result was certainly worth it.
The depth of the pier berthing areas is designed to allow Los Angeles and Virginia Class Submarines to berth at SUBASE.
“The subs need a 36-foot draft in the water and the depth must be correct to ensure they don’t run aground and to allow the base divers to perform maintenance and inspections under the subs,” said Meagher.
Another major benefit of the dredging project was the work completed in the Pier 15 dry dock basin. The basin around Pier 15 was dredged to its original depth of 60 feet to allow the return of the Auxiliary Repair Dry-dock (ARDM) which is used for submarine repairs at the base. The ARDM is designed to submerge beneath a submarine and then lift the sub out of the water.
“Dredging at Pier 15 dry-dock basin was essential to recertify the Shippingport [ARDM] facility to allow it to continue supporting Selective Restrictive Activities [SRA] Overhauls for our submarines,” said Meagher. “The basin had to be dredged to its original depth to allow the ARDM to take on Virginia class subs as well as Los Angeles class.”
Approximately 16,000 cubic yards of sediments were removed from the basin to bring it to the correct depth.
In the not to distant future there are plans to replace Pier 32 and move it to a more centered location between Piers 31 and 33. And a possible project in the future is the turning basin project for the northern piers to add clearance for the Virginia class subs to access Piers 31 through 33.
“Pier 32 is slated demolition for sometime in 2015,” said Meagher. “After the original pier is taken down, dredging will have to be done in the original pier location to bring it to the correct depth, as we can not dredge under the piers while they stand.”
Overall, the base Public Works Officer believes another comprehensive maintenance project will not be needed for some time.
“No one can control Mother Nature,” concluded Commander Frank Mulcahy. “But with this recent effort and some good luck, SUBASE’s waterfront and submarine berths should be good for another 20 years.”
Source: The Dolphin, March 11, 2010; October 14, 2008
