The Upper Trinity Regional Water District provides water and wastewater services to the rapidly growing region north of Dallas, Texas. This year, the National Association of Clean Water Agencies (NACWA) recognized Upper Trinity with a National Environmental Achievement Award for its Riverbend Water Reclamation Plant, which was recently expanded in order to keep up with development in the area. The plant now uses ballasted flocculation technology, allowing it to treat wastewater more quickly and in a smaller footprint.
In this interview, Upper Trinity Director of Operations and Water Resources Jody Zabolio speaks with Municipal Water Leader about the district’s experience in expanding the plant and choosing to implement ballasted flocculation.
Municipal Water Leader: Please tell us about your background and how you came to be in your current position.
Jody Zabolio: When I enrolled in college, I went into civil engineering. The first A I made in a civil engineering class was
in a fluids class, so on that basis I decided that water resources was my forte. After graduation, I went on to graduate school and received a master’s degree in civil engineering with a specialization in water and wastewater. After that, I went to work for a consultant that designed water and wastewater treatment plants for municipalities and utility districts. In 1996, I took a job with the City of Fort Worth as the assistant program manager for its capital improvement program to upgrade the sanitary sewer system. The city was under an administrative order from the U.S. Environmental Protection Agency to eliminate sanitary sewer overflows. After a couple of years, the director of the department asked me if I would be interested in getting involved in wastewater treatment, specifically as a plant engineer at the wastewater plant. I said yes. A number of years later, Upper Trinity had the need for a similar position. I was already familiar with Upper Trinity because I had done some work for the district back when I was a consultant. I went to work for Upper Trinity as a process engineer. A few years later, the assistant director of operations retired, and I was promoted to the position; I’m currently the director of operations and water resources.
Municipal Water Leader: Please tell us about the Upper Trinity Regional Water District.
Jody Zabolio: Upper Trinity was created by the Texas legislature in 1989 as a wholesale provider of water and wastewater services to smaller communities north of Dallas, primarily in Denton County. Today, we serve about 25 communities, some with water services, some with wastewater services, and some with both. Around 300,000 people live in our service area. We have two water treatment plants, one in Lewisville, the Thomas Taylor Plant, which is rated to treat 70 million gallons per day (MGD); and one in Audrey, the Tom Harpool Plant, which is rated for 20 MGD. We have four water reclamation plants, the largest being the Lakeview Plant in Lake Dallas, which is currently permitted to treat 5½ MGD of wastewater. Our Peninsula Plant in Oak Point, rated at 0.94 MGD, is under design to be expanded to 2 MGD. Our Riverbend Plant was recently increased from 2 MGD to 4. We also have the Doe Branch Plant, which is currently under construction to take it from 2 MGD to 4.
Municipal Water Leader: What are some of the district’s top issues today?
Jody Zabolio: We’re in a high-growth area, so staging the expansion of our system and bringing on new facilities to keep up with that growth is a top issue. We’re also focused on securing an adequate future water supply to address the long-term growth in our service area. A key strategy is the creation of a water storage reservoir, a new lake in East Texas called Lake Ralph Hall. We just received our U.S. Army Corps of Engineers permit, which will allow us to begin construction later this year, and we expect it to be online around 2025.
Municipal Water Leader: Would you tell us about the challenges of being in an area with a quickly growing population?
Jody Zabolio: It’s challenging to try and stay ahead of the curve, because it usually takes 2 or 3 years to go from identifying new needs to actually providing the facilities to meet them. It requires a whole lot of looking into the future and communicating with our customers about the speed of development and construction. You need to make sure that you have a planning horizon long enough to allow you to start the project in time to meet their needs.
Municipal Water Leader: Please tell us about the Riverbend Water Reclamation Plant.
Jody Zabolio: Riverbend was originally a greenfield plant created to serve the communities that were being developed in the northern part of our system. It was constructed and brought online in 2004. The plant originally functioned as a sequencing batch reactor, which treats wastewater in batches rather than as a continuous flow. That process tends to work well for a community in the early stages of growth but becomes difficult to operate when the growth reaches a certain level. In 2016, we had enough growth to expand the plant, and we converted it from a sequencing batch reactor to a normal, industry-standard activated-sludge plant. As part of that project, we implemented ballasted flocculation technology in the plant.
Municipal Water Leader: How does that differ from the technology used by a conventional activated-sludge plant?
Jody Zabolio: In the conventional activated-sludge process for wastewater treatment, you cultivate bacteria that consume the waste in the water. When they’re consuming, the bacteria get fluffy and sticky and agglomerate together, which allows them to settle out and be separated from the treated water. However, that settling process is somewhat slow. If you add a ballast or weight that the bacteria can cling to, they settle more quickly. In this case, we selected magnetite, which is a readily available, fully inert form of iron ore with a high specific gravity. Magnetite is naturally occurring and is obtained through a mining process. Because magnetite is iron, you can use a magnet to separate it out after the treatment process is done, recover over 90 percent of it, and put it back in the process. The ballasted flocculation process allows you to treat wastewater in a smaller footprint, because you don’t need as large a basin for the sludge to settle out in.
Municipal Water Leader: How much magnetite is used?
Jody Zabolio: The original amount of magnetite that was loaded into the 4 MGD Riverbend Plant was approximately 50,000 pounds, which actually turned out to be more than was necessary. We are currently feeding less than 100 pounds per day just to keep the equipment operational, allowing us to slowly reduce the amount of magnetite in the process. Once the recommended equilibrium is reached, we expect to regularly feed around 200–300 pounds per day.
Municipal Water Leader: How widespread is ballasted sludge technology?
Jody Zabolio: It’s been around for some time, but is still fairly uncommon in the industry. There are a number of technologies that use different types of ballasts. This particular method, known as BioMag, was created in the engineering graduate program at the Massachusetts Institute of Technology. There are a few plants up in the Boston area that use it, as do a handful of plants scattered through the rest of the United States. We took a trip up to the Boston area to visit some of the first plants that went online and were sufficiently satisfied with the viability of the process to attempt to get it permitted in the state of Texas. This is the first installation of its sort in Texas.
Municipal Water Leader: When did the first plants to use this technology come online?
Jody Zabolio: Ballasted flocculation has been around for over 20 years. However, the first BioMag installation was put in service in 2011.
Municipal Water Leader: What results have you seen from ballasted flocculation?
Jody Zabolio: The expansion facilities have been up and operational for 9 months now, and we’ve seen good results. However, we haven’t had a whole lot of rain in that time frame. Ballasted flocculation comes in handy most when you get higher-than-normal flows resulting from an influx of storm water. We have yet to see how it stands up to that, but we’re confident that the ballasted flocculation process is sound and provides us with another tool to better serve our customers.
Municipal Water Leader: What in particular was NACWA recognizing with the award it recently gave you?
Jody Zabolio: NACWA gave the National Environmental Achievement Award to Upper Trinity for operations and environmental performance. We focused on three aspects of our project in our submission for the award. One was to improve operations, converting our existing sequencing batch reactor to conventional activated sludge to better address the growing plant flows. We also doubled the existing capacity of the plant. By using ballasted flocculation, we were able to do that within our existing aeration basins, needing only to construct clarifiers to convert to conventional activated sludge. We also used an alternative delivery process called construction manager at risk, which brings the contractor on board as part of the design process to help with constructability and accelerate the schedule. That allowed us to go from design to construction in a more seamless manner and in a shorter time frame.
Municipal Water Leader: Do you have any advice for plants that might be considering implementing ballasted flocculation?
Jody Zabolio: First and foremost, if they’re looking to pursue ballasted flocculation, they need to check with regulators within the state and make sure they’re on board with the treatment process. Because a BioMag installation had never before been permitted in the state of Texas, we had to go through quite a bit of work in order to verify its effectiveness and justify its benefits. We had to perform a full-scale demonstration at one of our other plants to collect the data and get the information that the state needed to feel comfortable with the new process. If the process hasn’t already been permitted in their state, they should expect a bit of a longer planning horizon. We worked closely with the vendors and the design engineers and talked to the operators to discuss concerns and lessons learned and to make sure they were comfortable using the technology.
Municipal Water Leader: What is your vision for the future of the district?
Jody Zabolio: Our vision is to continue to serve our customers’ water and wastewater needs at an affordable rate and to keep up with growth by providing top-notch facilities in a timely fashion.