Barataria Restoration Utilizes Encapsulated Lightweight Aggregate

• Teaser: The Barataria Basin Landbridge Shoreline Protection project is a restoration campaign conducted by the United States Department of Agriculture Natural Resources Conservation Service (USDA NRCS). This long-term effort is designed to protect vital marshes and wetlands from further damage.
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  In this coastal preservation project, large bags of geotextile fabric are filled with lightweight aggregate produced at one of Arcosa’s production facilities. The bags, armored with riprap, help reduce wave energy impacting shorelines and protect adjacent marshes.

New Orleans Firm Chosen for Project

Pontchartrain Partners, LLC, based in New Orleans, was the engineering firm chosen to work on the Barataria restoration. Led by Bart Cook, P.E., President and Chief of Construction Operations, Pontchartrain Partners brought extensive expertise to this coastal project. Barlow “Bart” Cook, a licensed Professional Engineer in multiple states, has over 20 years of experience in heavy civil, marine, and mechanical construction, covering both private and government sectors. His work includes managing large-scale projects such as coastal restoration, levee construction, dredging, disaster recovery, and pump station repairs.

“The project was needed to alleviate loss of land for the most part,” says Cook. “Building barriers is the most important part to preventing wave action and energy surges that eat away at the land masses. This has caused major issues in the state, and we lose a lot of land every day. This land bridge project is part of a major effort to protect the New Orleans area and Lafourche Parish.”

Arcosa Lightweight’s Bill Wolfe explains that, in the past, ordinary boulders were used for similar projects, but Louisiana’s soft, compressible soils posed challenges for heavy materials.

“Prior to using lightweight, ordinary normal weight rock was used for these types of projects. The problem was, you never knew exactly how much material it was going to take to build the protection berm. Since the soil is so soft, the heavy rock would just sink into the mud,” says Wolfe.

“The nice thing about lightweight is it doesn’t sink.”

A bulk shipment of lightweight material was sent by barge to a staging area where the contractor placed the aggregate in giant fabric bags. Once sewn shut, these bags, weighing roughly 3,500 pounds each, were placed on another barge and shipped to the remote location along the Louisiana coast. “On the barge, we had a crane with four load points lift up the bags,” says Cook. “You had three different operations going on. First, you laid down a fabric base, then you laid down the lightweight bags, and then you put rock on top of that to armor the bags and the land behind it. They were placed in the water based on a specific sequence. It was just like a train.”

Using lightweight aggregate encapsulated in geotextile bags was a first for Cook’s firm. “In a typical design, you just put the riprap on top of the natural ground, but in South Louisiana, that rock will just disappear. At first, I wasn’t aware of lightweight aggregate. But using this light material as soft core is smart. This is the only product I’ve seen that really alleviates the sinking, and I saw it firsthand,” Cook says. “It’s lighter weight with less direct forces on the soils to sink in and penetrate.”

TThe $13.5 million project used an estimated 28,000 cubic yards of lightweight aggregate, 123,000 square yards of geotextile fabric, and around 124,000 tons of riprap. “After doing that four-mile stretch, this project was a great learning process for us,” says Cook. “We’ve got a great team of folks set up now, and I can’t see not using lightweight again.”

Civil Engineering Magazine Highlights LWA Breakwaters

• Teaser: In January 2021, Civil Engineering, the magazine of the American Society of Civil Engineers (ASCE), published a thorough article about the massive land-saving project along the 26.5 mile section – with an emphasis on a specific 9.2 mile stretch of marshland – bordering the Gulf of Mexico in Cameron and Vermillion Parishes.
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  The article, titled “Breakwaters Aim to Halt Ongoing Erosion at Coastal Refuge”, was written by Robert L. Reid, the magazine’s senior editor and features manager. Of particular note were comments from Brett Geesey, P.E., Coastal Project Manager at HDR Engineering, who says:

“Only the lightweight aggregate core breakwater, which lost only 3 ft of land, met all our criteria.”

The article explains that HDR Engineering previously used lightweight aggregate concrete (LWAC) breakwaters in Louisiana, but only in interior water systems — never along an exposed gulf shoreline.

Arcosa’s encapsulated lightweight aggregate played a crucial role in preserving Louisiana’s valuable coastline. While the Civil Engineering article provides a detailed read, Arcosa’s Bill Wolfe explains exactly how the company’s lightweight aggregate contributes to the success of coastal breakwaters.

Wolfe describes the process: “The clay used to create our lightweight aggregate is mined onsite at Arcosa’s production facilities,” he explains. “It’s fired in a rotary kiln to about 2000°F, reaching a near-molten state similar to lava. During this phase, the material releases gases, forming tiny air voids within the clay. Once cooled, it’s no longer clay but a durable ceramic aggregate ideal for coastal applications.”

Arcosa Lightweight and Industrial Fabrics have partnered for years on coastal preservation projects, refining their products for durability and longevity. The process of creating breakwaters has become seamless and is performed directly on-site.

The lightweight aggregate is placed in geotextile bags by the contractor on site, sealed, and positioned along the shoreline, then capped with riprap. These breakwaters have proven both environmentally friendly and highly resilient, withstanding storms and tidal forces for nearly two decades.

Wolfe notes that the geotextile bags are essential for keeping the material in place, which is especially critical in soft subsurface areas like Rockefeller Refuge. Previous efforts using traditional stone failed as the stone would simply sink into the mud, requiring constant replacement and escalating costs.

“Ordinary stone, well it sinks in the mud basically,” Wolfe explains. “It settles. Sometimes it would sink so fast that they could never break the water line. They just kept adding stone, and it would just keep sinking.”

The combination of Arcosa’s lightweight aggregate and Industrial Fabrics’ geotextile bags has significantly benefited Louisiana’s coastline. Since its creation in 1920, the Rockefeller Wildlife Refuge has lost 15,000 acres, with more than 300 feet of land disappearing in recent years. The need for effective solutions has grown, and in 2000, the Louisiana Coastal Protection and Restoration Authority and the National Marine Fisheries Service launched the Rockefeller Refuge Gulf Shoreline Stabilization Project.

The focus was on a severely eroded 9.2-mile stretch of the refuge in Cameron Parish, designated as ME-18 under the Coastal Wetlands Planning, Protection, and Restoration Act. This project, valued at over $33 million, successfully halted the erosion that had caused severe land loss.

Arcosa Lightweight is committed to supporting projects that preserve our coastlines, demonstrating how effective engineering and innovative products can help conserve these vital resources.

Lightweight Utilized in Pointe-aux-Chênes Coastal Restoration Project

• Teaser: Arcosa’s lightweight aggregate is ideal for addressing the geotechnical challenges of marshland environments, as demonstrated by its use in the completed enhancement of the Pointe-aux-Chênes Wildlife Management Area in coastal Louisiana. The Louisiana Department of Wildlife and Fisheries, tasked with improving the marshland’s productivity, used Arcosa’s lightweight aggregate to mitigate geotechnical challenges posed by the region’s weak subsurface soils. This material was essential in constructing parking lots and rehabilitating boat launches, providing a stable foundation despite the difficult marshland conditions.
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  The project, spread across Terrebonne and Lafourche parishes, used funds allocated for remediation following the 2010 BP oil spill. Jesse Noel, P.E., a former Project Manager at Delta Coast Consultants, led the enhancement design, which faced the challenge of extremely poor subsurface soils along Island Road. Noel, now a Regional Director at the Southeast Louisiana Flood Protection Authority – West, explained that these soils, extending 50 to 60 feet below the surface, posed a significant risk of excessive settlement.

“We got the geotech report back and there was a lot of concern about the soils,” Noel says. “There was the potential for excessive settlement at some of these sites if we were to load them up with limestone as the backfill material and parking surface.”

Photo Courtesy: Coastal Protection and Restoration Authority

Project Overview

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The Pointe-aux-Chênes project involved six sites, five of which were parking lots with accessible fishing piers. A vinyl sheet pile bulkhead was constructed at each site, backfilled with Arcosa’s lightweight aggregate. The sixth site included a boat launch rehabilitation, also utilizing lightweight aggregate behind a bulkhead.

Arcosa’s Terry LeJeune collaborated closely with Noel to identify the most suitable products for the project’s needs. After considering several options, they selected a blend of 5/8” and ¼” lightweight aggregate that would offer durable backfill while minimizing consolidation pressures. The choice of lightweight material proved advantageous, particularly in controlling the loads on the sheet pile bulkheads and reducing settlement risks.

Despite working with lightweight aggregate for the first time, Noel had seen its successful application in other coastal projects in South Louisiana. Arcosa’s guidance helped the project achieve the desired balance between durability and ease of installation. Noel reported that the material compacted well and allowed for rapid placement, providing a stable foundation to support the stone surface course.

Final Result

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The lightweight aggregate has performed exceptionally well since its placement. “It’s holding up really well,” Noel says. “It was placed and compacted rapidly with a skid steer and firmed up nicely to accept the stone surface course.”

The remediation work is expected to last up to 50 years, though settlement rates and sea-level rise may impact long-term performance.

“We have experienced a lot of overtopping on the roadway due to tides and storms,” Noel explains. “That’s another concern and [we will see] how that plays out with some other parts of the roadway, not necessarily our structures.”

He expressed confidence in the material’s continued performance in the face of environmental challenges.

Would Noel use Arcosa Lightweight’s products again? “Absolutely,” he says. “For specific applications, when backfilling bulkheads, I think it’s a pretty good value for what you get.”

• The Issue: Poor subsurface soils (50-60 feet deep) posed a risk of excessive settlement, making traditional backfill materials unsuitable.
• What Arcosa Did: Arcosa’s lightweight aggregate was chosen to stabilize parking lots, piers, and boat launches, providing a durable foundation in difficult marshland conditions.
• Why Lightweight Works: Lightweight aggregate reduced consolidation pressures, provided a stable foundation, and minimized settlement risks.
• Result: The lightweight aggregate has performed exceptionally well and is expected to last up to 50 years.
• Key Quote: “It’s holding up really well,” says Jesse Noel, P.E. “It was placed and compacted rapidly with a skid steer and firmed up nicely to accept the stone surface course.”
• Industry Context: Coastal projects benefit from lightweight aggregate due to the material’s ability to perform in weak soil conditions while controlling settlement risks.
• Lessons Learned: Collaboration between engineers and material suppliers, like Arcosa, is crucial for ensuring project success in challenging geotechnical environments.
• Call to Action: Discover how Arcosa’s lightweight aggregate can provide reliable, cost-effective solutions for your next coastal restoration or geotechnical project.
• Project: Pointe-aux-Chênes Wildlife Management Area Enhancement
• Location: Terrebonne and Lafourche Parishes, Louisiana
• Customer: Delta Coast Consultants LLC
• Client: Louisiana Department of Wildlife and Fisheries
• Project Size: Six sites, including parking lots and a boat launch

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