New vessel allows greater reach for scientists

A team with the U.S. Army Engineer Research and Development Center developed a vessel that provides new capabilities to U.S. Army Corps of Engineers’ scientists and engineers.

The coring barge, designed by researchers Jarrell Smith, Thad Pratt, and William Butler of ERDC’s Coastal and Hydraulics Laboratory, allows researchers to take sediment samples in areas otherwise inaccessible with conventional equipment.

The 28-foot barge drafts only nine inches and can be independently powered by a 40-horsepower outboard motor. Built by Bean Marine Fabrication in Washington, it is equipped with a collapsible drilling rig that can take core samples from up to 20-feet below the sediment surface. The drilling rig is configured for hydraulic direct push and a low-frequency hammer drive. The vessel can also accommodate a vibracore head used for sediment sampling.

 “We configured the barge to accomplish several new missions,” said Smith, who helped design and field test the coring barge. “The barge’s shallow draft and self-propulsion allows to move a drill rig into an area that would otherwise be very difficult or impossible to access.”

Typical drilling rigs are land-based, mounted on larger vehicles, or are designed for ocean drilling on much larger barges. The new coring barge can be moved by trailer virtually anywhere it’s needed.

A 32-foot push boat, known among the team as the “landing craft,” was developed with the barge. It has an enclosed cabin and twin 200-horsepower engines to navigate faster moving water. The landing craft has an A-frame and winch with 3-ton lifting capacity to deploy and recover scientific instruments. Its nickname comes from the drawbridge-style ramp on its bow, which lowers to allow access to the barge and makes it easier for ERDC’s dive team to get in and out of the water. The barge and landing craft can be used in tandem or independently, both able to support sediment core sampling in areas previously inaccessible to researchers.

One of the primary missions in which the barge can be applied is on Corps reservoirs to study sedimentation and erosion.

“A lot of districts are looking at reservoir management as a way to also manage sediment bypassing,” Smith said. “When they’re managing flood routing through the reservoir, they also bypass sediments. There is a delta that forms where the river meets backwater of the reservoir that will be exposed to high flow and high shear stresses and possibility of down-cutting.”

That down-cutting erosion moves sediment from the reservoir delta. Districts want to determine how much sediment is mobilized and how far it is transported: does sediment continue downstream of the dam, or is it simply moved to another location in the reservoir? With the coring barge, researchers will be able to collect samples in the shallow upstream areas of the reservoir and provide that data to districts.

“Another area of interest in USACE is river diversions into wetlands in places like southern Louisiana,” Smith said. “When rivers are diverted into wetlands, we also expect some down-cutting into the wetlands, and we can’t anticipate what effect that have without collecting the sediment sample in that environment.”

In October, Smith and a team of four other researchers from ERDC’s Coastal Hydraulics Laboratory took the landing craft and barge for a test run on the Mississippi River near Vicksburg, Mississippi, home to ERDC’s headquarters and four of its seven laboratories.

“One of the first jobs we were approached for is one that will push the envelope of what the coring barge is designed to do, working in about 20 to 25 feet of water in fast-flowing water on the Mississippi River,” Smith said.

The test run close to home gave the team an opportunity to get familiar with operating the drill rig, as well as anchoring the barge using its four spuds and a three-point anchoring to collect samples in a variety of locations and conditions.

“Once we had that experience under our belt, we’re confident that we’ll be able to execute that work once the river stages permit,” Smith said.

The test run also provided a degree of satisfaction in seeing their design become a reality that can serve ERDC and the Corps of Engineers.

 “Many of the studies we perform are for planning and feasibility, so much of work we do, we don’t see constructed,” Smith explained. “It’s nice to have that vision of what is possible, and have it arrive and be able to use in the way we envisioned.”