Built to Grow: Modular Precast Expands Wastewater Treatment Capacity in Louisiana
As development increased wastewater treatment demands in Louisiana's St. Tammany Parish, the existing infrastructure needed additional capacity years before a planned regional facility could be completed. With limited construction space and ongoing plant operations, the parish required a compact, expandable solution. Gainey's Concrete Products developed a modular precast concrete treatment system featuring custom 25,000-gallon tanks, clarifiers and supporting equipment. Completed in October 2024, the facility provides an initial treatment capacity of 100,000 gallons per day, with provisions for future expansion, while demonstrating how large-scale precast components can be manufactured and installed within challenging site constraints.
Fast Facts
- Project Name:
- Goodbee Regional Wastewater Treatment Plant
- Location:
- Mandeville, Louisiana
- Precast Products Used:
- On-site Wastewater Tanks, Wastewater
- Precast Producer:
- Gainey's
- Completion Date:
- Oct. 23, 2024
The Challenge
Residential and commercial development in St. Tammany Parish was placing increasing demands on aging wastewater treatment infrastructure. Although plans were underway for a future regional facility with a capacity of 5 million gallons per day, the parish needed additional treatment capacity well before that project could be completed.
The Goodbee site presented several constraints. Located between existing treatment facilities and near residential and environmentally sensitive areas, it offered limited room for construction and installation. The project also needed to minimize disruption to ongoing wastewater operations and address community concerns about noise and aesthetics.
Transporting and installing large treatment structures created additional challenges. Components had to travel along rural roads, fit within a confined site and accommodate difficult crane operations, including long-reach lifts and unstable soil conditions.
The project required a durable, compact treatment system that could meet immediate needs while allowing the parish to expand capacity as demand increased.
Precast Solution
Gainey’s worked with St. Tammany Parish engineers and Lonesome Development to develop a modular precast concrete wastewater treatment system tailored to the site’s space, transportation and operational requirements.
The system incorporated custom 25,000-gallon treatment tanks, clarifiers, equalization tanks, a trash trap, disinfection equipment, a blower building and integrated process controls.
The treatment tanks were designed as four-piece modular assemblies, allowing Gainey’s to manufacture large structures in transportable sections and assemble them on-site. The components included 10-inch-thick wall sections measuring 26 feet by 12 feet, making them the largest wastewater structures Gainey’s had produced.
To address transportation and lifting constraints, the project team optimized wall thicknesses, reinforcement and connection details. Custom lifting hardware, including an eight-point lifting system, accommodated components weighing up to 60,000 pounds.
The structures incorporated self-consolidating concrete, crystalline waterproofing technology and an engineered tongue-and-groove joint system with ConSeal CS1800 elastomeric sealant.
Gainey’s handled approximately 85% of the project work, including production drawings, manufacturing, quality control, assembly and installation. Specialized crane operations were performed by Deep South Crane.
- 100,000 gallons Initial per day wastewater treatment capacity
- 500,000 gallons Planned expansion per day capacity, with provisions for additional future growth
- 25,000 gallons Capacity of the custom treatment tanks
- 60,000 pounds Maximum reported weight of individual precast components
- Leaks during the system's initial filling
Why Precast?
Precast concrete allowed the project team to develop a large-capacity wastewater treatment system within a limited construction footprint while maintaining the flexibility needed for future expansion.
Modular construction: Manufacturing the tanks in four-piece assemblies made it possible to transport oversized structures along rural roads and install them within the confined project site. This approach reduced the amount of on-site forming and concrete placement required.
Manufacturing precision: Controlled plant production allowed Gainey’s to maintain dimensional accuracy across large structural components. Engineered tongue-and-groove joints and elastomeric sealant provided watertight connections, helping the system achieve zero leaks during its initial filling.
Reduced site disruption: Off-site manufacturing shortened field construction activities and helped minimize interference with existing wastewater operations and surrounding residential areas.
Custom engineering: Precast allowed the team to optimize wall thicknesses, reinforcement, lifting hardware and connection details for the project’s transportation and installation constraints.
Long-term flexibility: The modular design supports future treatment capacity expansion without requiring the existing facility to be completely replaced.
Together, these advantages made precast concrete suitable for delivering a permanent, expandable treatment system where conventional on-site construction would have been difficult.
Results
The Goodbee Regional Wastewater Treatment Plant was completed Oct. 23, 2024, providing St. Tammany Parish with an additional 100,000 gallons per day of wastewater treatment capacity.
The modular precast system was successfully transported and installed despite limited site access, challenging soil conditions and demanding crane lifts. According to the project submission, the engineered joint system achieved zero leaks during the initial filling of the treatment structures.
The completed facility provides additional wastewater treatment capacity while the parish continues planning for its larger regional infrastructure needs. Its modular design incorporates provisions to expand capacity to 500,000 gallons per day and potentially beyond as future demand increases.
The project demonstrates how custom precast concrete construction can accommodate large treatment structures, maintain watertight performance and provide flexibility for expanding wastewater infrastructure within a constrained site.
- Written by:
- National Precast Concrete Association
- Source:
- Goodbee Regional Wastewater Treatment Plant, Built for Purpose Awards submission
- Published:
- October 26, 2026
- Last Update:
- Oct. 26, 2026
Testimonial
"Their precast concrete design allowed for faster construction, minimal disruption to surrounding areas, and a finished product that is both durable and visually unobtrusive."
Project Manager, Lonesome Development LLC
