Project Details

Location: Freeport, Texas
Customer: City of Freeport
Solutions: Steel Concentric Wastewater Activated Sludge Treatment Plant
Capacity: 1.6 million gallons per day

Challenges

#1 Maintaining uninterrupted service
#2 Scale-related complexity
#3 Managing an unanticipated need for foundation remediation
#3 Ensuring continued regulatory compliance

A new concentric treatment plant allowed the city to expand capacity with no interruption in service

Aerial view of the Freeport, Texas steel concentric wastewater treatment plant expansion

Concentric wastewater treatment plant constructed adjacent to existing facility in Freeport, Texas

Freeport sits along the Texas Gulf Coast at the mouth of the Brazos River, where port activity, industry, tourism, and coastal living intersect. This economic diversity places sustained performance and reliability demands on the city’s wastewater infrastructure.

To support long-term growth and maintain regulatory reliability, the City of Freeport initiated a major wastewater treatment upgrade, consisting of a new full-capacity plant, while maintaining uninterrupted service to the community. Seven Seas Water Group, through its Houston-based subsidiary, AUC Group, executed a complete 1.6 million GPD steel concentric wastewater treatment plant featuring an 80-foot clarifier within a 130-foot concentric chamber next to the existing facility. This parallel plant strategy minimized operational disruption and positioned the city for a controlled transition once the new system reached stable operation.

Maintaining Uninterrupted Wastewater Service During Expansion

The project required coordinated site planning, structural precision, and sequencing discipline to ensure continuity of service.

The concentric configuration consolidates aeration, clarification, and hydraulic processes within a compact circular footprint, reducing site disturbance and simplifying long-term plant layout.

Construction activities included the erection and assembly of the concentric steel units, integration of process equipment, and alignment of a large-diameter clarifier and its supporting mechanisms.

Building next to an operating plant required careful staging, access control, and safety management. Tie-ins were sequenced to protect existing flows and maintain regulatory compliance. The layout also accounted for the anticipated demolition of the legacy plant once the new system achieved stable performance, reinforcing the project’s parallel build and controlled cutover strategy.

80-foot clarifier inside 130-foot concentric wastewater treatment chamber in Freeport, Texas

Foundation work and structural installation at Freeport, Texas wastewater treatment plant

Scaling to a 1.6 MGD Concentric Wastewater Treatment Plant

The Freeport installation was the first installation incorporating a WAWCON clarifier after Seven Seas’ subsidiary, AUC Group, acquired WAWCON, expanding its internal design and fabrication capacity. The project included the largest clarifier installed by AUC to date, an 80-foot unit integrated into a 130-foot concentric chamber.

Scaling to this diameter increased structural and mechanical complexity. Foundation loading tolerances tightened, lift planning required greater precision, and field fit-up and alignment demanded disciplined coordination. Operational reliability expectations also increased at scale, particularly within a concentric configuration, where hydraulic relationships must remain consistent across the system.

The Freeport plant’s scale demonstrated Seven Seas’ capability to deliver larger municipal wastewater infrastructure while preserving the structural efficiency and compact footprint associated with concentric steel design.

Foundation Remediation and Structural Risk Management

During construction, a subgrade geotechnical review identified a critical foundation issue. Installed helical piles were shallower than anticipated and couldn’t reliably deliver the required load-bearing capacity for the plant’s foundation. The condition introduced structural and schedule risk, particularly given the size of the concentric units and the large diameter clarifier.

Seven Seas directed corrective action to restore design intent. Helical piles were driven deeper until they met the required bearing criteria, ensuring adequate embedment and load-transfer capacity for the concentric steel units and clarifier loads.

Because the foundation issue was identified after installation, it carried rework implications and required immediate coordination between field crews, geotechnical specialists, and engineers. Foundation performance is directly tied to long-term structural integrity, so the correction was necessary to preserve structural reliability and long-term performance of the facility.

Delivering Large-Scale Municipal Wastewater Infrastructure

Expanding municipal wastewater capacity traditionally involves extended procurement cycles, capital budgeting constraints, and operational risk during construction. The Freeport installation illustrates how parallel-build execution and controlled commissioning strategies can mitigate those risks.

Beyond conventional design-bid-build approaches, alternative delivery models — including build-own-operate and lease-based structures — allow communities to modernize infrastructure with greater financial flexibility and performance accountability. By aligning engineering execution with long-term operational oversight, municipalities can reduce upfront capital exposure while maintaining regulatory reliability.

To discuss phased expansion, concentric plant design, or alternative delivery models, contact Seven Seas.

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Wastewater Treatment Plant Expansion<br> in Freeport, Texas