JOINT BASE LANGLEY-EUSTIS, Va. –
Joint Base Langley-Eustis’ Third Port, the U.S. Army’s pier complex sitting where Skiffe’s Creek meets the James River, recently completed a multi-month dredging project.
The dredging, a 24/7 operation taking place April 18 – June 15, was part of a regularly scheduled maintenance, which occurs every five years.
“Five years is just a historical mark,” said Jay Dehart, 733rd Logistics Readiness Squadron harbormaster. “We've figured that within five years [Skiffe’s Creek] starts filling back in. Where the river turns faster, water goes around the corner on the inside, slower water on the outside, causing huge amounts of sediment in the channel.”
The cyclical nature of the water’s current necessitates the dredging as filled-in waterways can impede ship movement in and around the piers. Those ships using the piers, because of buildup of sediment, were getting hung up there. At the piers are cargo ramps, which allow for a ship’s bow ramp to lower for the embarkation or discharge of cargo. Some of these ramps were no longer accessible due to the sand and silt accumulation as the regular five-year mark approached.
“The controlling depth of the channel going in is 20-feet deep. Most of those boats are drafted in about 14 [feet],” said Dehart. “And so as [the boats] were coming in the channel, they were actually running aground at low tide. So it was time to come in and clean it all back out; get [the depth] back out to 20 [feet].”
The dredging itself utilized a cutterhead dredge, which is like a gigantic vacuum cleaner. A barge suspends a big bit into the water, which goes down and breaks-up all the mud and clay at the bottom. The shaft of the drill bit is hollow, and as it's chewing up the sediment, it's also sucking it up into the dredge plant. The dredge plant pushes it through several miles of pipeline to a dredge spoil site.
This is where the Fort Eustis Dredged Material Management Area comes in. The FEDMMA, which sits between Mulberry Island Road and Harrison Road, is a 100-acre spoil site maintained as part of the dredging cycle. The area has built-up berm walls sufficient enough in height to provide capacity for dredged material, while also allowing for water runoff into Milstead Creek. This runoff feeds back into the James River watershed.
“[The FEDMMA has] just the capacity for the next maintenance dredging,” said Carolina Gonzalez-Zapata, 733rd Civil Engineering project manager. “We had very good dredged material that we want to reuse, and that's going to be [used] to raise the berm [levels].”
The U.S. Army Corps of Engineers tests samples of the material pumped out of the river for viability in other projects. The right material is desirable to build beaches or shore-up areas of natural erosion. During this most recent dredging at Third Port, part of the maintenance included reinforcement of the FEDMMA berm walls with pumped material, which will save the Air Force money as it circumvents the need for bringing material from elsewhere. The berm walls are now between 30-40 feet in elevation.
When this operation ended, the dredging had removed 491,426 cubic yards of material from the bottom of Skiffe’s Creek.
The last part of the dredging operation is a series of USACE-performed side-scan sonar readings to ensure no debris or detritus larger than a shoebox remained.
“Prior to dredging, [USACE did] a survey,” said Dehart, “and there were over 300 items laying on the bottom of the river that were identified, and it wasn't stuff that was thrown over. We had a tugboat, rudder fell off; we had a jet boat, the nozzle blew off. Some of it is maintenance related issues: Soldiers working on the side of the boat, wrench slips, and that kind of stuff happens when you work on the water.”
Now, the planning begins for the next dredging in five years, during which USACE maintains upkeep on the FEDMMA so it is available when needed.
“This dredging supports the 7th Brigade, which is all the large grey hull boats down [at Third Port] that deployed to worldwide locations from here,” said Dehart. “It also supports all Army watercraft training, so no matter where you're at in the world, if you're an Army Mariner, you come back here to Fort Eustis, to Third Port, to do your schools. So the impact of this not being dredged is huge.”