City of Gastonia Phase 1 Water Treatment Plant Upgrade

Using Membrane Technology Sets the Standard of Water Treatment Across the Tar Heel State.

With 76,000 residents across 52 square miles, the City of Gastonia has grown 350-fold since its formative days as a railroad town supporting the textile industry with a steam-powered mill. And while it still intersects the Atlanta and Charlotte railroads, the city is home to a far more diversified economy than its humble beginning. As part of the Charlotte Metropolitan Area, Gastonia has experienced the region’s robust growth and economic development of the past two decades. In fact, the city’s 30-year projection suggests by 2035 that parts of the city will see population growth as high as 130 percent.

Built in the 1920s, Gastonia’s Water Treatment Plant, initially designed to support a quiet mill town, was structurally failing and would soon no longer be able to produce enough clean water for its citizens.  When the City reached out to LaBella Associates in 2009, two treatment trains out of an existing ten had already been decommissioned due to structural concerns and demand was expected to exceed the capacity of the plant in 2019 – the timeline was critical.

LaBella served as the prime firm and provided civil, mechanical, electrical, plumbing, structural and fire protection engineering services as well as architectural design. The first phase of the renovation and expansion of the Two Rivers Water Treatment Plant included the rebuilding of process trains to support surface water membrane filtration, upgrading electrical feeds, upgrading mechanical systems, renovating lab and office space, new perimeter security upgrades, as well as a new 5.0MG clearwell and new SCADA systems.

Initially, the City had engaged another engineering firm to study the plant and make a recommendation on how to solve this problem. The findings of this plan proposed building a completely new plant, on a different site, at a cost of 230 Million dollars and decommissioning the existing facility. After realizing they could not make this work due to budget constraints, Gastonia reached out to LaBella Associates to see if there was another way to solve this problem.

As a result, LaBella developed a four phase approach to satisfy the City’s budget requirements, and the first phase aimed to provide a membrane treatment process that would provide a higher-level water quality at a capital cost equal to conventional treatment and increase plant capacity to 12 million gallons a day (12MGD), all while remaining on the existing site which dramatically reduced costs. While surface level membrane technology is proven and accepted in other states, North Carolina had not permitted a single surface water membrane treatment facility anywhere in the State. Conventional treatment uses sand and anthracite to filter and treat the water and membrane technology is an “ultimate barrier” which filters out particulates, bacteria and viruses to ensure a higher-level water quality. This membrane filtering process has typically been more expensive to implement and raises costs for the customer, which is one of the reasons our state was behind in moving forward with this technology.

Phase I of the plant was completed in 2018 and successfully became the first in North Carolina to implement surface water membrane technology. The result has been positive for the City, which has made itself a leader in driving the technology throughout the state. In addition, rates for Two Rivers Utilities’ customers have stayed nearly the same, while ensuring a higher-quality of water for over 100,000 residents. Particularly with our current health crisis, this technology is incredibly important for the future of public health in our state, as membranes can filter our bacteria and viruses from drinking water that traditional methods cannot.  This new plant will set the standard of water treatment across the state of North Carolina.

Special Considerations for This Project

Social/Economic & Sustainable Design

In order to implement a membrane treatment process in the City of Gastonia, LaBella had to consider two things in our design: efficiency and sustainability. After the initial pilot study was completed, it was evident that the membrane filters were most efficient when treating raw water. The more coagulants introduced upstream of the filters resulted in a tendency to clog or bind the filters, causing more frequent backwashes and cleans.  Working with state regulators, the project team arrived at a compromise between traditional 4 hour sedimentation basin detention time and direct raw water feed and designed a 2 hour sedimentation basin.  This modification allowed us to reduce concrete and steel costs to offset the cost of the new membrane technology, in addition to increasing efficiency of the membrane treatment process.

Sustainability was another key factor in successfully implementing the membrane technology. In a conventional treatment facility, you lose 6-10% of the treated water within your plant during cleanings and washdowns of filters and sediment basins. Typically, this water is not re-used and is transported through the sewer system to a nearby wastewater treatment plant. LaBella designed a second-stage membrane filter process that treated this used water. By utilizing a more robust membrane fiber, usually seen in wastewater facilities, the City was able to recover and treat 99% of the water entering the facility. Ultimately, this second-stage process saves citizens money, utilizes more of the water in the distribution process, and reduces energy costs at the plant itself.


In order to make this plan work, LaBella and the City met periodically with stakeholders from the North Carolina Department of Environmental Quality (DEQ) to educate state regulators and provide a level of confidence in the team to successfully implement and move forward with the plan. This included site visits, presentations, and meetings with various membrane technology manufacturers to familiarize the state with the process and its benefits. After nearly a year, the DEQ allowed the City to proceed and the State awarded this project the maximum single project loan of $35 million dollars from the State Revolving Fund (SRF) which is funded by the Environmental Protection Agency (EPA).

In addition to this trailblazing effort, this project took forethought and courage from the City of Gastonia to implement for additional reasons: Firstly, this was the single largest project the City had undertaken in its history. Secondly, the plant needed to remain operational while upgrades were made – this is equivalent to working on a car engine while it is running. This meant it was imperative that the plant still continue to filter and treat water for local residents throughout the duration of design and construction.

LaBella has been a very positive force throughout the six-year long, $65M upgrade of the City of Gastonia/Two Rivers Water Treatment Plant. This project is, by far, the largest project ever undertaken by the City of Gastonia and has been a daunting task for all of us. LaBella’s steady guidance and creative abilities have made the project so much better, each step of the way.Ed Cross
Division Manager of Water Supply and Treatment
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Gastonia Water Treatment Case Study

The City of Gastonia/Two Rivers Utilities Water Treatment Plant Upgrade Phase I was a recent finalist for the Research Triangle Cleantech Cluster Water Innovation Awards. This award recognizes a water or wastewater project that uses innovative cleantech solutions to create positive impacts for environment, economy, and residents.

LaBella was honored to partner with The City of Gastonia on this important project which brought surface water membrane technology to citizens at a cost equal to conventional treatment. Learn more about this technology in this case study uses innovative cleantech solutions to create positive impacts for environment, economy, and residents.