Advanced System Ups Quality for San Elijo Plant

San Elijo Joint Powers Authority water reclamation facility protects ocean water quality and provides a drought-resistant recycled water supply.
Advanced System Ups Quality for San Elijo Plant
Ravy Chea, SEJPA senior lab analyst, tests the plant’s daily reclaimed water sample.

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As a small wastewater/recycled water agency with just 21 employees, the San Elijo Joint Powers Authority (SEJPA) has accomplished big things.

In 2016, it was named Recycled Water Agency of the Year by WateReuse California in the medium-size category, recognizing the agency for its leadership, creativity and persistence in developing recycled water as a valuable local water supply.

That would not have happened without exceptional teamwork. “Our operations staff, led by operations director Chris Trees, P.E., shows incredible initiative, flexibility and intellectual dexterity to innovate and improve treatment and delivery of high-quality recycled water,” says Mike Thornton, P.E., SEJPA general manager. “Also, we have a visionary board of directors who take a broad view not only of the functional work we do, but of the greater positive impact we can have on our community.”

The SEJPA owns and operates the San Elijo Water Reclamation Facility. The wastewater system includes the treatment facility, eight lift stations and the San Elijo Ocean Outfall, co-owned with the city of Escondido.

The water reclamation system consists of tertiary treatment facilities, 19 miles of recycled water distribution pipelines, and three recycled water reservoirs holding 750,000 to 1 million gallons.

The authority wholesales recycled water to the San Dieguito Water District, Santa Fe Irrigation District, Olivenhain Municipal Water District and the city of Del Mar to irrigate fairgrounds, golf courses, parks, school properties and highway rights-of-way. Says Thornton, “The success of our recycled water program is built on collaboration with our water district partners. Together, we’ve created an award-winning program.”

Continuous improvement

The water reclamation facility, in Cardiff by the Sea, was built in 1965 and operated by San Diego County. As flows increased and the Clean Water Act took effect, the plant converted to advanced primary treatment in 1981, increasing capacity from 2 mgd to 2.87 mgd. The facility’s management and operations was transferred from the county to SEJPA in 1986.

In 1992, secondary treatment facilities and other upgrades increased capacity to 5.25 mgd. In 2000, tertiary treatment was constructed, along with 17 miles of distribution pipelines, two reservoirs and one booster pump station. The tertiary system included 2.5 mgd of continuously backwashing sand filters (Parkson Dynasand) followed by sodium hypochlorite disinfection.

Recently, the system was upgraded to include an additional steel reservoir and more distribution pipelines. An advanced water treatment facility, built in 2013, includes a 1.4 mgd microfiltration system (Pall Corporation) and 0.5 mgd reverse osmosis system (Water Equipment Technologies - a Xylem Brand) that can be expanded to 1 mgd. The facility operates in parallel with the sand filters to produce 3 mgd of recycled water, about the same as the average daily wastewater flow.

Wastewater entering the reclamation plant is treated with bar screens and an aerated grit chamber before it flows to the primary sedimentation basins. From there, it is sent to equalization basins to attenuate daily peak flows. It is then sent to conventional activated sludge basins equipped with anaerobic selectors before final clarification in rectangular secondary clarifiers.

Primary sludge is sent directly to anaerobic digesters; waste activated sludge is first sent to dissolved air flotation thickeners and then to the digesters. The digested material is dewatered with belt presses that regularly achieve 20 percent solids. The dewatered biosolids are trucked to farms in Arizona for land application. Digester gas is used to heat the digesters.

Today, SEJPA serves about 40,000 people over 19 square miles, including the cities of Solana Beach, Encinitas, Del Mar and parts of Rancho Santa Fe. The authority produces some 450 million gallons of recycled water per year. The water reclamation facility is permitted to discharge up to 3.02 mgd of tertiary-treated water to recycled water users, and up to 5.25 mgd of secondary effluent to the Pacific Ocean.

The arid San Diego area relies heavily on water imported from the Colorado River and Northern California; recycled water helps the community conserve potable water.

Advanced water treatment

The advance water treatment system has greatly improved recycled water quality. “Historically, we struggled with high TDS in the recycled water, partially from local water supplies and partially from water softeners within the service area,” says Trees. “Often, TDS ranged from 1,100 to 1,300 mg/L. Now, our TDS levels are in the 700 to 900 mg/L range.”

System construction went smoothly. “Operators reviewed the design during meetings with the design team and with representatives of the equipment manufacturers, who also provided on-site training,” Trees says. “From these meetings, the staff developed standard operating procedures for operation and system cleaning.”

The SEJPA team worked closely with Kennedy/Jenks Consultants and Trussell Technologies on operations improvements to fine-tune the biological process. Those included adding an anaerobic selector, enhanced dissolved oxygen control and monitoring, temperature monitoring of the mixed liquor, and remote monitoring of the waste activated sludge TSS to help optimized wasting rates.

“The outcome of the process improvements is better-quality secondary effluent as measured by TSS and turbidity, which improves operational efficiencies in the recycled water process,” Trees says.

The staff enjoys being part of system upgrades and optimization. After the process control improvements, they began developing process control algorithms to automate and optimize the biological process.

“From this, they developed mathematical equations that correlated influent temperature with the optimal solids retention time for maintaining non-nitrified treatment, which is the lowest-cost treatment, since SEWRF has ocean-discharge options,” says Thornton. From the temperature-SRT correlation and TSS monitoring of the waste activated sludge, Casey Larsen (SCADA manager) and Trees developed programming logic for automatic wasting and for process control based on influent temperature.

Although the new systems have increased the operators’ workload, the water quality improvements have been worth it: “The wastewater treatment has been exceptional, and recycled water salinity levels have been significantly reduced, which is a major benefit for our customers who use the water for irrigation,” says Thornton. “Also, the better water quality has allowed us to expand the customer base into industrial applications. We now serve two cooling towers that previously would not use the recycled water because of its high mineral content.”   

Well trained

A team of seven operators keeps the water reclamation facility running smoothly. The plant is staffed 10 hours a day, and an operator is on call outside those hours. “Every operator is certified and trained to operate all the equipment,” says Trees. “They are assigned to focus on certain areas with monthly rotations.”

SEJPA encourages cross-training, as operators often assist in the laboratory, on facility maintenance projects, and in operating and maintaining wastewater lift stations. Most operators have at least one certificate in a secondary field, such as mechanical technologist or laboratory analyst.

Reporting to Thornton are Trees and Paul Kinkel, director of finance and administration, who supervises Jennie Basco, administrative assistant, and Carrie Cook, accounting technician. Reporting to Trees in addition to Larsen are:

  • Dale Kreinbring, chief plant operator
  • Mike Dietrich and Todd Hutchinson, lead operators
  • Aaron Simonson and John Boyle, operator II
  • Eric O’Riley, operator I
  • Scott Best, operator in training
  • Mike Konicke, associate engineer
  • Mike Henke, mechanical supervisor and wastewater operator
  • Jose Garcia and Jim Barnett, mechanical technicians
  • Ravy Chea, senior laboratory analyst
  • Susie Arredondo, laboratory analyst

The greatest challenge is balancing pursuit of opportunities, like expanding the recycled water system and improving treatment, with facility maintenance and succession planning.

“We encourage individual and team goal-setting to develop our employees and increase job performance,” says Thornton. “Our team is highly motivated and well trained. That results in exceptional job performance, strong budget controls, good permit compliance, and an impressive safety record.”

Future goals

The authority plans to continue expanding its recycled water network and customer base by improving recycled water to suit diverse applications. “As the regulations evolve, there may be opportunities to pursue in potable reuse,” Thornton observes.

The authority has also experimented with capturing urban runoff to protect beaches and lagoons, and redirecting that water to the sewer system for treatment and reuse. “The collection of runoff and first-flush stormwater has to be handled carefully,” says Thornton. “Otherwise it could hydraulically overload the conveyance system or treatment plant, or affect process biology.” The SEJPA operates three low-flow runoff stations that collect dry-season runoff and some limited first-flush flow for treatment.

The authority has started planning to increase recycled water storage and expand microfiltration capacity. Other capital projects in progress include headworks upgrades, anaerobic digester and dewatering system improvements, and replacement of multistage centrifugal blowers with turbo blowers for process air.

Whatever the future brings, Trees is confident the staff will excel: “Our strength lies in the unity of the group. We work as a team to solve problems and achieve our goals. Our motto is: We win as a team.”


Highly decorated

The San Elijo Joint Powers Authority (SEJPA) has collected some 40 awards since 2003. Besides the Recycled Water Agency of the Year Award from WateReuse California in 2016, the authority won three 2015 awards from the California Water Environment Association:

  • Operator of the Year – Mike Dietrich, lead operator
  • Laboratory Person of the Year – Susie Arredondo, laboratory analyst
  • Electrical/Instrumentation Person of the Year – Casey Larsen, SCADA manager

Says Chris Trees, operations director, “During 2015, Mike Dietrich led the operations team into an increasingly complex and demanding operations environment. He showed exemplary leadership during one of the most dynamic years in our plant’s history.”

For example, he performed troubleshooting on the primary influent and digester ferric addition systems to find the cause of unusually high intermittent chemical usage. After reviewing treatment process parameters, laboratory data and the chemical addition system, he found that occasional high storage tank levels were causing the chemical to be pushed past the peristaltic pump heads and hoses.

Arredondo goes above and beyond to help make facilities safer and better. As a safety committee member, she shared ideas and developed training sessions. Says Trees, “She is readily available to help the operators with extra lab tests, equipment calibrations and whatever else is needed to help make their jobs a little easier.” She also volunteers time on weekends to staff the authority’s booth at community events, teaching the public about water reclamation and conservation.

Larsen has made big contributions in upgrading facilities, and planning and designing capital projects. For example, he developed a program to automate the aeration system for the activated sludge process to optimize energy use based on dissolved oxygen setpoints. “This work was paramount to the overall project, which is saving 900,000 kWh each year,” says Trees. Larsen also implemented an energy-savings program for recycled water distribution. The program controls pump runtimes to minimize operations during periods of on-peak energy prices.

Says Mike Thornton, general manager, “We have a very passionate and dedicated staff. They choose to be engaged in the industry and seek high levels of certification. They take great pride in the results we produce.”



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