British company Fish Guidance Systems Ltd specializes in fish guidance equipment. They were set to work alongside Barr Engineering (Barr) as the prime contractor in a new study-based project in Kentucky, and hired Nelosca Technologies, Inc. (Nelosca) to help execute their revolutionary endeavor.
Asian Carp and the Barkley Lock and Dam
The full project name is a mouthful: the Barkley Lock and Dam Bio-Acoustic Fish Fence System project, or Barkley BAFF for short. Nelosca was contacted as a qualified contractor to assist in both design and construction due to our marine expertise. Since most of the BAFF installation would take place underwater with dive assistance, this would be a great project for us.
The Barkley BAFF project aims to prohibit upstream movement of Asian carp. Asian carp are a non-native fish species to southeastern American waterways, introduced decades ago to control weeds and aquatic parasites. But Asian carp began to out-eat, outgrow, and essentially decimate water habitats and ecosystems. Over the years, Asian carp migrated up American river ways and are now spreading throughout the Tennessee River Valley.
The hope is that the BAFF system will begin diverting Asian carp, keeping them downstream of the Barkley Lock. If it works well, additional systems will be installed to contain these fish. Design work began in the fall of 2018.
The United States Fish and Wildlife Service is the end client of this project as it’s federally funded; the work also involves many other stakeholders to ensure proper management. The United States Army Corps of Engineers-Nashville District (USACE), University of Minnesota, Travis Construction, and Collier Electric were also included—in addition to Fish Guidance Systems, Barr, and Nelosca.
* Silver carp or "jumping carp" photo courtesy of the United States Fish and Wildlife Service
BAFF System Technology
Nelosca spent the first several months consulting with the USACE and other stakeholders, reviewing plans and estimating construction costs. We officially began work onsite in May 2019.
Five precast concrete units comprise the system, installed downstream of the lock at the bottom ofthe river channel. The precast units feature speakers, high-intensity lights, and a bubble system, which effectively creates a sound-and-light bubble curtain. The local contractors dubbed the project the “fish disco.”
Asian carp are highly sensitive to sounds, lights, and disturbances within the water. The fish disco will safely create a barrier that corrals the fish south of the Barkley Lock and Dam. The system hasn’t been tried to prohibit the movement of Asian carp before; it’s generally used to guide migration patterns in other fish species. This is a test study for all involved.
Installing a Bio-Acoustic Fish Fence System
The most intense aspect of the project was finding a way to create a trench at the bottom of the river channel in which the BAFF concrete units could be set. The units must be positioned beneath a specific elevation to allow barges to pass overhead, but incredibly hard bedrock covers the bottom of the river channel.
With limited time onsite and the extremely high costs associated with the work, we designed this project to “go big or go home.”
We rented the largest milling head Antraquip® makes, an AQ‑6, and attached it to a CAT® 374D 170,000‑LB class excavator. High water has been a major factor in delays. Over the summer, the water was approximately 20 FT higher than where we could effectively mill the bedrock.
We attempted to create the trench with divers, but there was simply too much bedrock to effectively complete the work in the available time frame. The AQ‑6 mill head had to do the job!
Remote Operated Vehicle Inspections
This entire project is unique—from planning to execution and follow up. After finishing construction, Nelosca will continue to conduct visual inspections using a remote operated vehicle (ROV).
We will perform inspections multiple times during the first few weeks following installation to observe the structures. Over the next three years, Nelosca will continue intermittent inspections and provide ongoing maintenance support for the BAFF system.
Our services moving forward will include maintenance of the underwater and mechanical systems, silt monitoring, and potential dredging over the next few years of the planned study.
Nelosca Barkley BAFF project crew:
Raen Schechinger (project manager),
Mike Weiers (superintendent),
Blake Rocque (dive superintendent),
Paul Hovenga III (dive superintendent),
Mike Rice (estimator).
