The Los Angeles County Sanitation Districts (LACSD) are among the largest water/wastewater agencies in the country, operating 10 water reclamation plants and one ocean discharge wastewater treatment plant. The job of running them is truly a challenge.
Just talk to Joe Chang, supervising engineer in the Water Reclamation Plants operations group. Chang notes that running that kind of complex system is a constant educational experience.
”I’ve been working in operations for 14 years, and I learn something new about one of the plants almost every day,” he says.
So what challenges make the job complex?
It starts with the problem many plants have around the country: aging infrastructure.
“A lot of our plants were built in the 1960s, so we have old tanks, old piping, old buildings. Our mechanical equipment is aging,” Chang says.
Much of what’s in the facilities is reaching the end of its design life, so every day, decisions must be made about the best way to operate and monitor equipment, do the necessary repairs or replace parts.
“We also have to know what contingency plans there are in case of failures,” Chang adds.
A second challenge is also one that faces a good portion of the country: the aging and retiring workforce. At LACSD, “We have a very experienced and knowledgeable staff,” Chang says. “But many of them are closing in on retirement age, and as they retire, we lose institutional knowledge about the plants and equipment they’ve been operating for such a long time. How do you carry that over to younger staff?”
LACSD has a mentoring program, and experienced staff works closely with newer employees, but Chang admitted it is tricky to find ways to convey the knowledge that’s been accumulated. The districts use manuals and more experienced staff to conduct training for newer operators and are trying to capture legacy information by taking actions such as studying criticality of equipment and working through different scenarios to see what would happen if systems fail. These facts are recorded so new operators understand what steps to take if problems arise.
Derek Zondervan, supervising engineer in the Field Engineering Section, added that LACSD is also trying to put a focus on professional development. “The custom VMA training we just had was great [The group held a VMA Basics Program in February 2018]. It’s very valuable to have industry experts bring staff up to speed, so that they are all on the same page regarding specifying, installing and operating valves,” he said. “Otherwise some fine points can become an afterthought.”
Through the Basics Program, “Joe and his staff members in operations, field engineering and design were all getting the same training at the same time,” he adds.
Basil Hewitt, supervising engineer in the Public Information Office at LACSD, also refers to retirement as a problem, specifically, the exodus of baby boomers. He says LACSD is handling it better than many similar organizations.
“We’re working hard to ensure there is continuity of knowledge,” he says.
Aging infrastructure presents a more troubling challenge, he says.
“Some of our infrastructure has been in use for almost 90 years,” he points out. “Joe and Derek do a great job of rehabbing and fixing, but we need to make sure we have funding to address the infrastructure issue.”
California is well known for strictness in environmental matters, but LACSD says the agency is also dealing well with those issues.
“Our mission is to protect public health and the environment. So the bottom line is that whatever is good for the people we serve, we do, provided it’s cost-effective,” says Basil.
Still, “our agency has operated differently than many sanitation districts from the beginning. We took wastewater off the shoreline using ocean outfalls, while others were discharging directly at the beach,” Basil says.
Chang also notes that LACSD facilities are designed with a good amount of redundancy, which helps with both infrastructure challenges and environmental concerns.
“Even though we have aging infrastructure, we have enough redundancy that if a pump or valve or air compressor or aeration tank went offline, we would still meet our environmental requirements,” he says.
Like many water districts, LACSD also faces challenges created by the new “flushable” wipes being pushed on the market. Chang says that in the wastewater collection portion of the districts, there is a critical need to de-rag equipment because many of those wipes clog up the pumps and screens at the districts’ pump stations.
Hewitt stresses that the public should be told that most of the wipes do not flush harmlessly away.
“We see it in our pumps, and we’re looking into how we can spread the word that these wipes are not flushable.
LACSD’s long history includes an early foray into recycling.
The districts started as a wastewater agency in 1923. In the 1940s, the second chief engineer for the agency recognized the value of recycled water and started planning water reclamation plants.
The districts’ first tertiary effluent plant was constructed in the 1960s. Since 1962, the organization has reused over a trillion gallons of water.
“Every year, we generate about 130 million gallons of tertiary effluent (a.k.a., recycled or reclaimed water),” says Hewitt. The water “is indistinguishable from bottled water, and there are more than 850 sites throughout L.A. county that use the recycled water,” he adds.
The districts’ largest treatment plant, the Joint Water Pollution Control Plant, is in Carson. Hewitt notes water from that plant has been too salty for reuse because much of the wastewater comes from industry.
However, “we’re exploring how to cost-effectively recycle this wastewater and use it to recharge groundwater aquifers,” he says.
To do so, the organization is partnering with the Metropolitan Water District of Southern California, which is building a demonstration facility that would further purify the effluent produced at the Carson plant. If the project runs smoothly, “we could potentially get 150 million more gallons per day going back into the water supply,” he says. This is significant since currently half of the water used in L.A. County is imported from the Sacramento Bay Delta or the Colorado River.
Also, since Los Angeles is in a semi-arid region, many issues arise regarding water supply. A severe drought between 2012 and 2017, for example, brought the importance of conservation to the forefront, and while there has been a slight uptick in rain the last year, the districts are working diligently to make the water supply more resilient.
“The reservoirs throughout the state are not at comfort level,” Hewitt says. Because of this, “We have to ensure that the water keeps flowing. If there is another drought or if something happens to an aqueduct, we could have a problem. So, we’re moving ahead with more water recycling.”
Chang addresses the issue of water conservation’s effects on equipment. Because with reclamation, “There is less flow, but it is more concentrated, we considered whether that would create problems with more odor or corrosion,” he explains.
The agency has always been aware of this issue, but staying ahead of it is a constant process.
“Fortunately, we haven’t experienced any issues associated with the reduced flow, even though the waste is more concentrated. That’s because we’ve been pro-active all along,” he says.
Zondervan points out the advantage of that reality. Drought is more the norm than the exception now, so conservation measures will continue to keep flow rates down, even when there isn’t a drought.
Still, the pursuit of better and better ways to reclaim water isn’t going away anytime soon.
“As long as you flush the toilet and use the shower, you need water.” Reclamation is “an important, reliable source of water for our region,” he says.
MEETING TODAY’S CHALLENGES
Zondervan has worked in wastewater and solid waste design for the last few years, just recently moving to field engineering. He says that while no recent major changes have been made in the districts’ system design process, it’s a constant process finding innovative and cost-effective ways to keep operations up and running smoothly.
For example, “We’re always looking for better materials and designs. We look back at the way we did things before and see how they’ve held up. Then we can decide if that was the best way and make changes accordingly,” he says.
One challenge today comes from the variations in flow coming into the treatment plants, he says. For example, a huge wash of wastewater hits the sewer system shortly after people get up in the morning. That slows down during the day but then there is another, somewhat smaller upswing after people return home from work. Flows then drop to very low levels during the night. This creates a challenge for operators who must keep the chemicals at the right levels, and it also causes spikes in energy use.
Because of this, the districts have a flow-equalization tank at the Valencia Water Reclamation Plant and are currently building a second such tank at the San Jose Creek Water Reclamation Plant. These tools will capture those peak flows in the morning, store them until the night and then send them back into the system, thereby enabling stabilization of electricity needs and chemical additions, and optimizing treatment.
Chang says this will help spread out the load from higher concentrations of wastewater over the day and make more recycled water available for the overnight hours when irrigators use the water for parks, golf courses and other tasks.
Hewitt notes that the LACSD operates two landfill sites and has a power plant at the Puente Hills landfill that closed in 2013. A network of pipes collects landfill gas, which is about 40% methane. However, it’s burned to produce nearly 50 megawatts of electricity to power the districts’ San Jose Creek plant, administration offices and homes.
Another power generation system is in place at the plant in Carson, Hewitt says.
“All the biosolids that settle out from six of our upstream water reclamation plants are sent to the plant in Carson. Once the solids are removed there, they go into anaerobic digesters where microorganisms break down solids, generating methane to power the treatment plant,” he says.
“This 20-megawatt power plant saves about $9 million a year,” which makes the plant energy self-sufficient, he says.
State regulations about pulling organics out of landfills created another special program for the districts, Zondervan says.
Because flow rates are down from conservation, the digesters at the plant in Carson don’t produce as much gas. As a result, the agency is embarking on a project to turn collected food waste into a slurry and putting it into the Carson plant’s anaerobic digesters to generate more biogas and power.
The demonstration phase of this program was just completed, and the districts are working to bring it to full scale to generate more power from food waste.
“This is an example of being innovative and cost-effective. The state comes up with a new regulation, but we had to figure out a way to get it out of landfills and into the digesters and have that food waste become a resource rather than a burden,” Zondervan says.
HELP FROM MANUFACTURERS
The districts say that manufacturers can help in the constant effort to keep up with better ways of doing things.
Chang recounts a project where several valves were installed simultaneously years ago that are now all coming to the end of their life at the same time.
“This goes towards overall maintenance strategy of infrastructure,” he says. “We need something in place where we can track cycle times on valves, especially critical valves.”
This might be a tool that allows tracking what a valve can do when it has cycled many times.
“That would help us figure out if maybe we need to stagger how we’re using the valves so they don’t get burned out all at the same time,” he says.
Such ideas go along with the idea of remaining proactive, Zondervan says. “One thing we have appreciated is the support from manufacturers on the design side with specifying.” But it also includes tools such a lunch-and-learns and educational material.
The lessons are “a big help to us. There are so many different valves and applications so it’s helpful to get input,” he says.
Hewitt adds that a new, 18-foot (5.5-meter) diameter, 7-mile-long (11 kilometers) tunnel is being built from the Carson plant as part of a redundancy plan to support the tunnels originally built in 1937 and 1958.
“There is always flow going through these tunnels,” he said, “so we can’t take them out of the service for inspection.”
Because of that, “we’re going to need some very large, 144-inch valves,” he says.