The Water Resources Department staff in New Smyrna Beach, Fla., saves big on electricity by optimizing reclaimed water system pressures
Irrigation customers who use much of the reclaimed water from the New Smyrna Beach (Fla.) water reclamation facility plant haven’t noticed a difference. Commercial irrigation storage ponds are still full, though it takes longer to fill them.
But the plant, owned by the Utilities Commission, City of New Smyrna Beach, has made substantial operational changes that are conserving energy and holding down electricity costs. By adjusting and optimizing pressure in the reclaimed water distribution system, the plant staff is saving about $140,000 a year. Similar changes at the drinking water plant next door are saving $100,000 a year while also reducing use from 199 gallons a day per connection to 195 with virtually no complaints.
Saving the resource
Built in 1998, the 7-mgd advanced treatment plant creates high-quality effluent, most of it reclaimed for irrigation for homes, golf courses, and other large commercial customers. “The water resource is very precious, especially in Florida, where there is a limited amount of freshwater and we’re surrounded by saltwater,” says Dave Hoover, director of the Water Resources Department.
The plant is allowed to discharge up to 30 percent of its treated water into the Indian River. Over the last three years, an average of 85 percent of the wastewater coming to the plant has been reclaimed. That number reached 90 percent over the last year. “We’re real excited about it,” says Hoover. “A lot of the investment our utility and ratepayers have made in irrigation piping and developing an adequate customer base has paid off,” Hoover says.
Water reclamation reduces the amount of drinking water used for irrigation and keeps more water in the aquifer. The ecological importance of that is always on Hoover’s mind, but recently his thoughts have been on system pressure. Less pressure in the system means less power demand from the plant.
Hoover got the idea for optimizing pressures from a local utility commercial. “The commercial said that by using two settings on your thermostat — one for when you’re at home and one for when you are away — you could save as much as 20 percent off your energy bill every month,” he recalls. “Another commercial said that if you reset your cruise control to 65 instead of 75, you could save 20 percent on your fuel cost.”
The wastewater plant had always operated with a system pressure of 75 psi. “I kept looking at that, and those commercials kept coming back to me,” Hoover recalls. “I became convinced that we didn’t need to put out 75 psi.” His goal was to use the many variable-speed drives (Yaskawa Electric America) in the plant to respond to demand on the system, rather than setting them for peak demand at all times.
The Utilities Commission had asked the Water Resources Department to evaluate every aspect of performance to see where costs could be contained and money saved in a difficult economy.
So Hoover worked with operators and the plant supervisor to refine the operating strategies and reduce the maximum pressure from 75 pounds to 70, and to limit the hours when the maximum pressure could be used. “The only time we allow 70 psi is the over-night hours when customers are allowed to use landscape irrigation,” he says.
“There is reasonable justification for running 70 pounds when you’re trying to use up reclaimed water as people are using irrigation systems, rather than dumping it into the river. But it only represents about 25 or 30 percent of the day.” To conserve water, the 732 residential irrigation customers are allowed to water lawns only during night hours, when less is lost to evaporation.
Outside of irrigation hours, treatment plant operators are now limited to 60 or 65 psi. That is adequate for filling seven golf course and commercial storage ponds. “It takes five hours instead of three, but we use less power,” he says. The ponds aren’t used for irrigation during the day, so there is no hurry to fill them.
The same is true of filling the plant’s own storage systems. “We have a 13-acre storage pond and seven million gallons of storage tanks, but when they’re full and the demand for reclaimed water is low, we have to discharge into the river,” Hoover says.
When that happens, the pressure is set even lower. “Nobody’s using any reclaimed water and you’re just releasing excess water into the river. Instead of doing it at 75 pounds and just pushing it into the river when it is necessary for operational purposes, let’s do it at 55 to 60 pounds.”
Hoover and his staff also modified and enlarged the plant’s own Hunter Industries irrigation system, and the plant becomes its own largest customer when others aren’t using reclaimed water. Nourishing the 800 acres of wetlands on the property can use a significant amount of water. “We’re managing our resources rather than losing that freshwater into the saline environment of the Intracoastal Waterway,” says Hoover. “That builds credibility and support with regulators and conservationists while protecting other ecosystems.”
After 33 years in the industry, Hoover says these are exciting times. “Wastewater treatment plants used to be called treatment and disposal facilities,” he says. “Now we’re recycling on the highest level we can. We’re taking domestic wastewater and cleaning it up to where it just about meets drinking water standards again. It’s cleaner than most lakes in Florida, and our lake water is exceptional. Our operation employees now see themselves as environmental stewards of one of our most important natural resources.”
Through irrigation, New Smyrna Beach is reducing demand on the state’s water resources. “Ninety percent of our water comes from the Upper Floridan Aquifer,” Hoover notes. “That is a finite water source that has very pure water. But if we draw water out too fast as the state grows in population and water demand, we can cause saltwater intrusion and ruin our water source to the point we have to go to desalination plants that are much more expensive.
“So our regulatory agencies, and all of us in the industry, are very motivated to try to clean up our wastewater enough so that we can safely distribute it as irrigation water.”
The entire commission staff looks forward to the day when nothing gets discharged to the river and ocean, says Hoover. “Our goal is 100 percent reclaimed water use, and we’re going to get there. Our strategy reduces the loss of water into the ocean, reduces excessive pressures, and cuts our energy costs.”