Operations, Maintenance and Management of the City of San Marcos Wastewater Treatment Plant

Since 2005, Jacobs has operated and maintained the 9-million-gallon-per-day (MGD) wastewater treatment facility in San Marcos, Texas, serving more than 80,000 residents. Over two decades, Jacobs’ high-quality service has led to out-of-scope work, impactful solutions and meaningful improvements to the local environment and community.

How? By investing in infrastructure, advancing innovation and building talent.

More than an operator

Jacobs uses a wide range of in-house capabilities to deliver innovative and progressive operational strategies that improve performance and manage costs. We completed or will complete several major capital improvement projects, including:

• Odor control rehabilitation
• Secondary clarifier center ring replacement
• Headworks improvements and installation of a third mechanical bar screen
• Solids dewatering system upgrades
• Wastewater treatment plant (WWTP) facility plan development

Piloting new solutions

The facility operates under some of the strictest permit limits in Texas for phosphorus removal. In response, the team developed, tested and piloted enhanced biological phosphorus removal using existing infrastructure, reducing the use of ferric chloride while meeting and exceeding permit standards. 

This approach cut chemical costs, improved efficiency and was featured in Texas WET and Water Environment & Technology magazines.

Proactive virus detection in wastewater

In 2020, Jacobs joined Biobot Analytics’ pro-bono COVID-19 campaign to test for SARS-CoV2 — the virus responsible for COVID-19 — in wastewater. In collaboration with Biobot Analytics and the city, Jacobs conducted COVID-19 wastewater monitoring through 2024 to proactively detect the re-emergence of the disease and made data readily available on the city’s website for residents.

Our team continues to expand on this out-of-scope work. We recently purchased a HACH Cepheid GenXpert unit — an automated polymerase chain reaction test — to complete the testing in–house and detect additional viruses in wastewater influent, such as Influenza A, Influenza B and RSV. The program also led to a new partnership with Baylor and the Texas Department of State Health Services that will monitor wastewater for norovirus, bird flu and measles. 

Academic collaboration with Texas State University 

Located in a college town, the San Marcos team works closely with students, faculty and researchers through hands-on learning and real-world projects. 

In 2021, Texas State University (TXST) Assistant Professor Dr. Ikehata launched a reclaimed water study of direct potable reuse (DPR) at the San Marcos WWTP to address regional water demand. The DPR pilot — a collaborative project between TXST, Jacobs and the City of San Marcos — aimed to develop advanced water treatment technologies that ensured a sustainable and reliable water supply for the community. 

The initiative included design, construction and operations of a pilot-scale advanced water purification system at the WWTP that:

• Is capable of producing 2,000 gallons per day of drinkable water
• Uses advanced purification methods like ozone-biological activated carbon, ultrafiltration, reverse osmosis and ultraviolet advanced oxidation process
• Produces pure water from treated wastewater that exceeds drinking water standards 

Dr. Ikehata and his students reported their initial findings in 2024 and will proceed to the next phase of research. In 2025, the study earned the Texas American Water Works Association Bob Derrington Reuse Award, and TXST has since added a wastewater course that includes regular visits to the WWTP. The university also recognized Jacobs with the TXST Department of Geology Outstanding Support from the Business Community Award. 

Training the next generation

Jacobs and TXST developed an operations and maintenance (O&M) internship program to support career growth in the water sector. Each summer, one to two students from TXST work onsite, learning how to run daily operations, test samples in the laboratory and understand the biological treatment process. Interns also spend time at other Jacobs O&M projects to learn about different facilities, processes and procedures.

The program allows students to gain real-life experience and provides Jacobs with the bench strength to accomplish projects beyond our scope of work. A number of interns have been hired as full-time Jacobs staff at the plant following their graduation, and the program has been replicated at other O&M projects.

Every July, the San Marcos project hosts a virtual tour of the WWTP and a question and answer session for Jacobs interns companywide to celebrate National Intern Day. 

Supporting the San Marcos community

Jacobs regularly works with the city and local organizations to support residents, stay connected to community needs and contribute to local programs: 

Keep San Marcos Beautiful: We engage in the city’s Keep San Marcos Beautiful program to help maintain the city’s environment. As part of the program, we adopted River Road — the road in front of the plant — as part of Adopt-a-Road and complete regular cleanups.

Great Texas River Cleanup: Since 2016, our team has joined over 700 volunteers to remove thousands pounds of trash and recyclables from the 90-mile San Marcos River. 

Community education: We host tours for school programs, residents, students, city employees and more to share how wastewater is treated and why it matters.

A healthy environment: Rio Grande Perch made their home and continue to reproduce in the WWTP’s final effluent re-aeration basin — proof of high-water quality. 

All of which makes for an award-winning team

The San Marcos project team has been recognized for safety, individual accomplishments, environmental excellence and community involvement. They include, but are not limited to, awards from:

• National Association of Clean Water Agencies
• San Marcos River Foundation
• Water Environment Federation
• Water Environment Association of Texas
• Texas Water Utilities Association
• American Water Works Association – Texas Section