By Andrew A. Kornacki, USACENovember 8, 2011
WASHINGTON, Nov. 8, 2011 -- Ft. Lesley J. McNair is a United States Army post on the tip of a peninsula at the confluence of the Potomac and Anacostia Rivers in Washington, D.C. It has been an Army post for more than 200 years, third only to West Point and Carlisle Barracks in length of service. With that many years in service, the operations and maintenance program is critical.
The fort and the surrounding lands are protected from the tidal waters of the rivers by a seawall about 6,000 feet long and more than 100 years old. There is no record of the wall ever being inspected and therefore the project condition needed to be determined.
In the spring of 2011, the U.S. Army Corps of Engineers' Engineering Research and Development Center, or ERDC, began to compare costs to complete an engineering inspection of the seawall to determine the overall condition of the structure. After reviewing contract and in-house proposals, ERDC awarded the work for the inspection on the seawall to the Corps' Regional Technical Services Dive Team.
The team, composed of Corps employees, currently comes from the Great Lakes and Ohio River Division and the North Atlantic Division. They are trained and experienced in a wide range of technical diving operations such as coastal and harbor inspections, lock and vessel equipment inspections and benthic surveys. The dive team for Ft. McNair was made up of divers from the Buffalo and Philadelphia Districts.
The mission to inspect the seawall hit its first roadblock before the team was even in the water: technical drawings of the construction of the seawall could not be found. Eric Kolber, Buffalo District's extraordinary librarian came to the dive team's rescue. He contacted the National Archive Cartographic and Map Office and was able to come up with a scan of a 100 year-old drawing containing the cross section of seawall.
This information allowed the divers to familiarize themselves with the wall before getting into the water. It also made the dive safer.
At the beginning of August, the dive team assembled at Ft. McNair to begin their mission. They spent two 12-hour days inspecting the seawall. A variety of inspection methods were employed including wading in the water and inspecting the wall at low tide and surface air supply diving to inspect deeper parts of the wall in high tide.
One distinct advantage that the dive team has is that their divers are licensed professional engineers, mainly in the structural and coastal engineering disciplines. This skill set would prove invaluable in the next phase of the mission: analysis and reporting.
After the dives were completed, the team members assembled the information, prepared a presentation, and met with officials at Ft. McNair. Since the presenters were both engineers and divers, they were able to speak from first-hand knowledge as to what they observed. This provided ERDC and the Fort with a comprehensive, detailed report on the condition of the seawall. A final report outlining the significant findings will be completed for them in the near future.
The Regional Technical Services Dive Team, though not well known, is an important Corps asset.
"Diving for the Corps provides a unique opportunity for us as engineers to actually see the project in its entirety and then directly use the information to provide a better design product," said Shannon Chader, chief of Buffalo District's Coastal and Geotechnical Engineering Team and a dive supervisor and diver.
Diver training combined with degrees in the fields of civil, structural, coastal, and mechanical engineering as well as biology gives the team the capability to execute just about everything from structural assessments to benthic surveys.
The dive team motto is: "Building Strong."