The Ogallala Aquifer is an essential source of water for America’s breadbasket in the west-central high plains. It is being drawn down faster than nature can replenish it, largely for farm irrigation.

The New Mexico city of Hobbs draws water from that aquifer — but about 3.6 mgd less today than years ago. The city’s wastewater reclamation facility now recycles essentially all of its influent, using it to irrigate a large farm, golf course, cemeteries and a soccer complex. That water displaces potable water formerly drawn from underground.

Meanwhile, biosolids from the treatment process are dried to create a Class A fertilizer/soil conditioner that the farmer spreads on his fields and city residents take home and apply to their lawns and gardens.

That end-to-end recycling initiative is a source of pride for Bill Griffin, facility superintendent, and his nine team members. It has also helped bring major recognition to the city. The plant earned the 2019 Max Summerlot Award from the New Mexico Water and Wastewater Association — it is the state’s highest honor for excellence in operations, maintenance, management, safety and professionalism in water reclamation facilities.

Griffin credits the success to his team: “It’s the standard they hold themselves to. They want to do good work. They want to be able to step back and say, ‘That’s good because of us. We did this.’ I also appreciate our city commissioners, city manager Manny Gomez, and our utilities director, Tim Woomer. Without Tim’s leadership, we wouldn’t be able to do what we do.”

PERVASIVE EXCELLENCE

The 2019 Summerlot award was the city’s fourth in consecutive years. The award alternates each year between wastewater and drinking water facilities. In 2016 and 2020, the award went to the Hobbs water side under Todd Ray, utility superintendent.

Hobbs, a city of 38,000 in New Mexico’s southeast corner, lies in an oil-producing area; its climate is semiarid. Its water reclamation facility was built in 1980 with preliminary screening, grit removal, aeration basins and final clarifiers. Effluent was then piped to a lagoon facility south of the city equipped with a sprinkler system.

That facility was abandoned in the mid-1990s after Hobbs developed a relationship with the farmer who now takes two-thirds of the city’s reclaimed water. There original treatment plant received a few upgrades over the years, including the addition of primary clarifiers and a centrifuge for solids dewatering. When the plant ran into capacity issues in 2002, plans were laid for a major upgrade, completed in 2010.

That $30 million project brought the design capacity to 4.8 mgd; today, average flow is 3.6 mgd.

The upgrade converted the primary clarifiers into grit chambers, enclosed all the influent piping, added a new headworks building and UV disinfection, and installed biofiltration for odor control throughout the plant. The bulk of the project was the construction of aeration basins for a modified Ludzack-Ettinger, or MLE, process for BOD and nitrogen removal.

MULTISTAGE AERATION

Submersible pumps (Flygt - a Xylem Brand) deliver effluent to a Channel Monster grinder and auger (JWC Environmental). The water then passes through a flowmeter (KROHNE) and Enviroquip grit chambers (Ovivo USA). The grit proceeds to a Eutek Systems washing system (Hydro International); the wastewater passes through a pair of 3 mm ESR Stair Screens (Vulcan Industries).

The flow then enters the MLE process with three parallel trains. “Where the internal recycle, return activated sludge and influent meet up, we have four anoxic zones with Flygt submersible mixers,” Griffin says. “No air is introduced there. We starve the bacteria for air so that they use the oxygen from the nitrate molecules in the influent. That’s where nitrogen is given off as a gas.”

The flow then enters the aerobic phase of the process with a series of three basins where dissolved oxygen is stepped down from 3 ppm to less than 1 ppm. “We first hit it with a lot of air to get the BOD-destroying microbes going again,” Griffin says. “Then we step it down so when the RAS and internal recycle go back to the front of the plant, the DO is at about 0.2 ppm.”

OUT TO IRRIGATION

After the final clarifiers (WesTech Engineering), the influent enters the UV disinfection system (SUEZ Water Technologies & Solutions) and then receives a small dose of chlorine to provide a residual in the reclaim water piping. The flow is then metered and sent to a 4-acre pond outfitted with SolarBee solar mixers (Medora) to await distribution.

“The reclaimed water is clear enough coming out of the plant that if you’re in a boat, you can see 6 feet down through the water to the liner on the bottom of the pond,” Griffin says. A bar screen (WesTech) removes algae buildup before the water enters a 25-foot-deep wet well containing two sets of pumps.

“The pipeline to the farmer has two 300 hp Goulds vertical turbine pumps. That is a low-pressure, high-volume system. In the same wet well, we also have three 100 hp Goulds vertical turbine pumps. Those pumps feed the recycled water system around our plant, feed the cemeteries and soccer complex, and charge the line up to the golf course.”

The pipeline to the golf course spans 13 miles and has purple-painted hydrants along the route that firefighters can tap to suppress grass fires. Another line, also with hydrants, runs to the farm and continues to the former lagoon treatment facility, which serves as a contingency outlet in case a problem occurs at the reclamation facility or the farmer needs to shut down irrigation. Any water sent there simply infiltrates the ground or evaporates.

The farm that receives reclaimed water lies 6 miles south. The water irrigates cotton and a rye cover crop by way of 14 quarter-section center-pivot irrigation systems with booster pumps.

THE SOLIDS SIDE

Solids wasted from the process go through rotary drum thickeners (Vulcan) into two aerobic digesters with VariOx jet aeration (Parkson Corp.) and Aerzen blowers. About every 30 days a centrifuge (Alfa Laval) is activated to dewater the material from 2% to 18%-19% solids. “That is a Class B biosolids,” Griffin says. “We are permitted as a contingency to send that to landfill.”

The dewatered cake is fed to a Fenton Environmental indirect thermal dryer (RDP Technologies), essentially a rotary kiln in which thermal oil at 450 degrees F circulates through a rotating plate heat exchanger. At the bottom of the unit, the oil passes through an additional chamber and transfers heat to the biosolids. The material is heated to 310 degrees F and emerges as 95% solids Class A product.

About 95% of the product goes to the same farmer who receives the reclaimed water. Hobbs team members pack the rest in bags given away to city residents. Its typical NPK nutrient analysis is 2.5-2.3-0.5. “We don’t sell the product,” Griffin says. “If you get into sales, you encounter legal issues such as guaranteeing the nutrient content. It is basically a low-grade fertilizer or soil amendment that people use as they would a good Class A compost.”

TEAM COHESION

Making it all work is a veteran core operations and maintenance group backed by newer team members. Robert Janousek, wastewater operations supervisor, moved up last year from an operations and maintenance role. “He is a really good all-around performer,” Griffin says. “He really digs into problems. He does the research and comes up with solutions. He’ll say, ‘We’re having this problem, but I think this will fix it.’”

Operator Ken Brotherton is an effective troubleshooter whose previous background as an electronics technician comes in handy when a piece of equipment gives an alarm or a process is upset. Operator Shane Cox is a maintenance specialist with an appetite for knowledge. Operator Roger Kibad is “a solid performer all around and a very sharp individual,” Griffin says.

Janousek, Brotherton and Cox have attained Level 4 (highest) wastewater operator certification; Kibad is expected to reach that level soon. Newer team members are operators Alan Trujillo, Lorenzo Sandoval, John Kunko and Clayton Murrish.

The city has to compete for talent with oil field companies in the area that pay significantly higher wages. “We’re listed on the job boards such as indeed.com and governmentjobs.com,” Griffin says. “We also advertise in our newspaper, and we’ve had quite a few inquiries by word-of-mouth. The last three people we hired came to us that way and are working out great.”

TAKING OWNERSHIP

The team has a knack for pulling together in the face of challenges. A year or so ago, staff turnover left the team six people short. The remaining team members juggled work schedules, took on extra shifts and kept everything running. “That included doing the maintenance work orders, mowing the grass, washing down the buildings,” Griffin recalls.

“We all talked it over. Some of us did shifts we didn’t really care for. Everybody worked with everyone. I need to give an honorable mention to Alan Trujillo, because he was rock solid on filling in. He and Roger Kibad took on weekend and evening shifts and really helped us out.”

In his leadership role, Griffin believes in letting the team members take ownership of the facility: “I call it sweat equity. There has been a lot of blood, sweat and tears invested in this plant. I basically let the employees do what they need to and give them what they need to do it: ‘What do you need from me? Do you need tools? Parts? Support? A piece of rental equipment? Here it is. Let’s get it done.’”

That seems to be working just great so far.