Moving to Ozone

The second largest water treatment plant in the U.S. changes disinfection methods, creating challenges for operators, solved by intensive training and teamwork.
Moving to Ozone
The Joseph Jensen facility is the largest water treatment plant west of the Mississippi.

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When the 14 operators at the Joseph Jensen Treatment Plant faced a major disinfection system upgrade in 2005, they rose to the occasion. They were challenged by a learning curve and a tight window to conduct acceptance testing and meet the disinfection byproducts regulation.

“We had been using free chlorine, but upgraded to ozone to improve the water quality and meet increasingly stringent regulations,” says Heather Collins, water treatment section manager for the Metropolitan Water District (MWD) in Los Angeles, which owns the Jensen plant in Granada Hills. “It took a lot of work for operators to learn the new system and switch things over.”

The plant formed an “ozone operation core team” of operators, mechanics, electricians and instrument technicians who worked closely with the water quality engineering compliance team to learn the system. “It was very intensive training, as the operators only had a month to feel comfortable with the ozone system before they turned off the chlorine feed to meet the regulatory deadline,” says Collins. “They really pulled together and met that deadline.”

The plant also implemented an emergency backup plan to switch from ozone to free chlorine and ammonia in case of a power outage or ozone system failure. Teamwork and an excellent training program led by plant manager David Dean help make the plant successful. A participant in the Partnership for Safe Water, the plant won the Phase IV President’s Award in 2012 and won national taste test awards in 1998 and 2008.

First to convert

Built in 1972, the Joseph Jensen plant uses conventional filtration to treat 250 mgd. As the largest water treatment plant west of the Mississippi and the second largest in the country, it treats enough water to fill the Rose Bowl in less than three hours, and supplies 6 million people in the San Fernando Valley, Ventura County, West Los Angeles, Beverly Hills, Santa Monica, South Bay, Long Beach, Palos Verdes and Northern Orange County.

The water source begins in the mountains, rivers and streams in Northern California, flows through the Sacramento-San Joaquin Delta, and enters the State Water Project’s 444-mile California Aqueduct. Water from the Jensen plant, and MWD’s four other plants, is piped to member public water agencies, who send it to retail agencies or directly to homes and businesses. Some local agencies mix MWD water with supplies from local wells before distribution.

In 1995, the Jensen plant was expanded from 450 mgd to the 750 mgd rated capacity. The upgrade doubled the number of filters and tripled the sedimentation basins and filter washwater reclamation treatment capacity. The ozone disinfection system went online in 2005, and in 2008 the plant added a chlorine containment facility, chlorine gas scrubbers (Siemens Water Technologies) and a fluoride system designed in-house.

After ozone disinfection, solids are removed by settling, and the water is filtered before final disinfection with chloramines. Residual solids are sent to drying lagoons, which are hauled away by a contractor and used as farm soil amendment.

Window of opportunity

Ozone upgrade construction began in 2002, and the system had to be operating by the July 1, 2005 deadline set by the state Department of Public Health. System installation was completed June 1, allowing one month for operators to switch the plant over from chlorine. The upgrade also included new chemical feed systems and a complete reconfiguration of the influent flow stream.

A liquid oxygen (LOX) storage facility contains three 44,000-gallon Ozonia LOX tanks and vaporizers that send oxygen feed gas to the ozone generator building. The ozone is injected into the water through fine-bubble diffusers in six 10-chamber ozone contactors. To keep bromate from forming during ozonation, sulfuric acid is added to lower the pH, and caustic soda is added afterwards to raise the pH back up.

Converting to ozone disinfection met the state’s Disinfection Byproducts Stage 2 rule, and reduces tastes and odors in the tap water that may be caused by algae growth in the source water.

Operators began classroom training on the ozone system in May, led mostly by consultant Kerwin Rakness of Process Applications in Fort Collins, Colo. Once the system was installed and started up, operators trained on a computer simulator model that exposed them to different operating conditions.

“All operators went through the simulator training where they had to adjust the ozone and bring it into the right zone,” says Collins. “We also involved the mechanical operations and maintenance team, since they are responsible for maintenance on the system. The biggest challenge for the operators was learning about the reliability of the ozone disinfection control system and the emergency chlorine system’s ability to replace ozone if the system tripped from a power blip or control system problem.”

If the plant should lose power, operators are trained to respond immediately and switch the ozone feed to chlorine. “We’re proud that we can provide adequate disinfection with free chlorine for 30 days, and we’ve built that into our emergency plan,” says Collins.

Keeping them fresh

Collins credits Dean for the smooth upgrade and the successful operation of the plant as a whole. “An engineer by trade, Dave is involved in every type of training and emergency preparedness we do,” she says. “He takes real scenarios, for example a chlorine leak, and gives the staff real-time training exercises. He gives everyone a role to play.”

Dean has implemented other successful programs that are part of MWD’s ongoing efforts to improve treatment effectiveness at all five plants. These include developing a chlorine system computer simulator model where operators can train in responding to chlorine system problems, leaks, and treatment performance issues.

Jensen plant operators have developed several electronic operational data sheets and checklists that improve documentation, operational consistency and training. “Part of these efforts is getting the operators directly involved with process equipment maintenance by preparing systems and conducting performance testing, in partnership with the mechanics, electricians and instrument technicians,” says Collins.

“With the new complex systems and aging infrastructure, the staff is dedicated to keeping a clean, neat and safe facility. Housekeeping is part of an MWD performance excellence program that incorporates a Japanese business practice known as 5S.” Translated to “Sort, Set, Shine, Standardize, Sustain,” the program has been proven to reduce worker injuries and system breakdowns and has improved operational performance.

Partnership goals

Since 2004, Jensen plant operators have been involved with the Partnership for Safe Water program. The plant had been an active AWWA member and wanted to take plant operation and compliance to a higher level.

“The operations staff, together with the water quality department, determined what the plant needed to do to meet the Partnership goals, and looked at different areas, such as turbidity levels with individual filters, the sedimentation basin process and the combined filter performance,” says Collins.

To meet the Partnership Phase IV goals, the plant had to maintain a filtered water turbidity less than 0.10 NTU more than 95 percent of the time, and less than 0.30 NTU for all sample locations. They also had to maintain a filter startup ripening goal of less than 0.10 NTU after a filter had been in service for 15 minutes following the backwash.

“The key to meeting these goals has been the consistent quality of the source water provided through two very large state project storage reservoirs, a solid history of treating the water for over 40 years, and diligence in recording, monitoring and adjusting treatment processes and water quality performance,” says Collins.

Smooth operation

The operators at the Jensen plant work as a team to keep the plant running smoothly. Besides collaborating on optimizing ozone generation, they work together on filter surveillance, filter slime removal, and plant shutdowns and startups. They use computer systems to partially automate chemical inventory and ordering, dosage calculations, communications between shifts and daily production logs.

Fourteen full-time operators work rotating three-person 12.5-hour shifts. They frequently offer improvement suggestions. “We used to inject 25 percent sodium hydroxide and 19 percent aqueous ammonia to the filter effluent with inline jet mixing,” says Dean. “The operators determined that the chemical injection of caustic before the ammonia caused calcium buildup on the ammonia injection lance, and they recommended swapping the injection points. This was very successful.”

Dean holds a T5 water treatment license and has been with the Jensen plant for 16 years. Operations manager Gordon Dexter has been with the plant for 22 years and holds a T5 license. His staff includes:

  • Plant operators Harold Jones (T4, D2 licenses, 9 years with the plant), Gilbert Lopez (T4, 38 years), Richard Pittsinger (T4, 20 years), Greg Reoyo (T5, D5, 6 years), Richard Rocha (T4, 23 years) and Eldon Wright (T4, 23 years)
  • Operator I Dustin Alleman (T2, D2, 1 year), Samuel Diaz (T2, D2, 2 years), and Jose Herrera (T2, D2, 1 year)
  • Operator II Bradley Hall (T3, D2, 20 years)
  • Operator III Sean Brennan (T3, D2, 1 year), Porter Hamilton (T4, D5, 1 year), William Pellowski (T3, 23 years), and Keith Stallworth (T3, 7 years)

Ongoing challenges

In spite of upgrades over the years, some of the plant’s equipment requires rehabilitation. “The infrastructure is the original and needs to be maintained,” says Collins. “We need a lot of money to support refurbishment, repair and, in some instances replacement, without affecting our rate structure. MWD water rates pay for operating all five treatment plants and provide funding for energy costs and capital bonds for the entire infrastructure. This encompasses 5,200 miles of service area and two major aqueducts that supply water to more than 18 million people.”

Another issue is finding enough trained staff.  An apprenticeship program helps fill positions. “We bring in new electricians and maintenance people and train them on the job,” says Collins. “It’s a 4.5- to 5-year program, and we pay them while they are being trained. Apprentices receive classroom and on-the-job training, and are partnered with a journeyman electrician or maintenance person.

The plant will continue with the Partnership for Safe Water Program, submitting data each year to renew Phase IV status. Dean’s preparedness training and other programs will continue. “Dave’s motto is ‘plan, develop, verify, maintain and prepare,’ and he does it well,” says Collins.

He keeps operators motivated with humor and a keen understanding of their work, and that allows him to have candid conversations with them. “It is not beyond Dave to get in there and assist employees when extra effort is needed,” says Collins. “His experience, empathy and understanding are among his greatest strengths.”

The plant maintains visibility with tours and has been featured in movies, television, photo shoots and commercials. Says Collins, “MWD balances support of the entertainment and advertising industry in the Los Angeles area with the need to operate, maintain and secure critical infrastructure. Our facilities offer visually unique and diverse filming opportunities, from both a historical and high-tech perspective. They especially like the new ozone generator building galleries and the water treatment plant tunnels.”


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