PITTSBURGH – Each time the excavator picked up a load of rocks and swung its booming arm to dump the stones into the water, the barge rocked from side to side, swaying with the heavy machinery’s momentum.
The construction vehicle sat on a flat barge anchored to the river bottom, but the excavator’s motion still caused the floating plant to sway.
Another barge, called a “hopper,” shaped like a huge rectangular bucket, held the stones for the clamshell claw to scoop up. Heavy ropes creaked with tension as they held the crane and hopper barges together.
“Watch your footing because this barge will keep rocking,” someone cautioned.
Over and over, the two platforms swayed apart and rocked against each other, clashing with a metallic bang, causing a small tremor under the feet of anyone standing on the float.
The rocks going into the water formed new fish reefs along the Monongahela River’s shorelines. The U.S. Army Corps of Engineers Pittsburgh District began work to install the reefs in late October. The reefs will offset disruption to the river and aquatic life that will take place when the district removes Elizabeth Locks and Dam in the summer of 2024.
“By demolishing the Elizabeth Dam, the flow of the river will change, so we did analysis to determine the effects it would have on the fish,” said Timothy Sturm, the civil engineer for the Pittsburgh District currently overseeing the construction.
Sturm took over the project from Claire Murphy, the technical engineer lead for the project until construction began.
“Claire is very thorough. She puts together packages that are top notch,” said Matt Rother, the section chief for the Civil Design section. “She is trusted with some of the district’s hardest projects, and she excels at it.”
One of Murphy’s priorities was informing boaters about the construction because the stone reefs will reach three feet below the water surface in some areas. Boaters might accidentally scrape or damage their motors if they are not careful. She spearheaded the communication effort by publishing public notices with the help of the legal and project management offices. She was also heavily involved with the Hydraulics and Hydrology team in modeling the reef to ensure they met the intent for environmental mitigation.
Removing the locks and dam in Elizabeth will cause a change in water levels and hydraulic flow in the river pool, disrupting fish habitats. The Pittsburgh District designed the reefs to offset potential harm to aquatic life.
“Building these fish reefs will help us mitigate ecosystem impacts from removing Elizabeth Locks and Dam, as well as merging pools 2 and 3 together,” said Steve Frost, the project manager for the Lower Monongahela River project. “We’re excited to see this project move forward.”
The Lower Mon project includes constructing the larger lock chamber at Charleroi Locks and Dam, which has been going on for two decades, and the removal of Lock and Dam 3 at Elizabeth, Pennsylvania, next year.
Removing the dam will help equalize the pool between the Charleroi and Braddock locks and dams, forming a 30-mile stretch of navigable waterway. It will benefit the navigation industry by cutting the transportation time required to pass through the region.
“Any time the Pittsburgh District takes on a construction project, we assess the environmental impacts as well as the benefits and seek to develop solutions that offset the impacts,” said Bobbi Jo McClain, the chief of the Environmental and Cultural Resources section for the Pittsburgh District. “These reefs will create diverse habitat breaks up underwater flows to provide refuge and feeding habitat for fish.”
Once the project is finished, the Pittsburgh District will have installed 73 reefs, each extending 50 feet perpendicular to the shoreline. Sturm estimated it will take approximately 9,000 cubic yards, or about 12,000 tons of rocks, to complete the reefs. The project forms 28.5 acres of fish reefs as a series of dikes that extend into the river from the shoreline.
“The reefs provide fish a place to settle outside of the river flow and rest as they continue on their journey,” Sturm said. “As sediment builds up, plants grow and help provide more food for fish to eat.”
Some of the fish most popular to anglers in the Monongahela River include black bass, sunfish, walleye, sauger, white bass, striped bass, musky and channel catfish.
“I think it’s a fantastic project,” said Derek DiFonzo, the crane operator who unloaded the stones into the water on behalf of the contractor.
DiFonso lives in Charleroi, Pennsylvania, just a few miles from his current worksite. He said working on the project felt like he was helping his own community.
“I grew up in this area of Pittsburgh. I love it here,” DiFonso said. “We are not only giving back to the environment but also benefiting future generations who live near here. It’s a lot of fun to do this kind of work. I really enjoy it.”
DiFonso estimated he unloaded about 550 tons of R5 stones in one day. He scooped and dumped each load continuously for hours, over and over again. He made the work look effortless, like a kid playing the claw game at an arcade, winning every time.
Except, planning the stone reefs was anything but child’s play. The design concept may be simple and efficient, but the work took a lot of coordination, Rother said.
“Murphy was very good at making sure everyone was informed throughout the planning process. She coordinated between different teams, and they all worked well together,” Rother said.
The district has been planning the reef project for years, ever since they announced the removal of the locks and dam at Elizabeth. Various teams considered every detail that might affect the river flow, impact the public, or threaten underwater habitats. Removing the dam benefits commercial navigation. The new reefs will benefit fish habitats, and therefore anglers. However, the new piles of rock underwater could surprise boaters who never had to deal with them before.
The Pittsburgh Districts asks all members of the public to take extra caution while operating boats along the shorelines. Boaters can find a map of the new reef location here: https://www.lrp.usace.army.mil/Media/News-Releases/Article/3568451
Internally, the district depended on experts from engineering and construction, environmental, hydraulics and hydrology, and planning sections to make the project a success. Externally, district engineers worked with the U.S. Environmental Protection Agency, U.S. Coast Guard, U.S. Fish & Wildlife Service, PA Fish & Boat Commission and PA Department of Environmental Protection.
“We did a lot of coordination with the public to ensure they understand what we’re doing. Communication is key across the board for our success,” Sturm said.