Sometimes the Truckee River flows clear.

Other times it flows like chocolate milk. The change can take place within minutes. Whatever the river water’s condition, the Truckee Meadows Water Authority turns it into drinking water at no more than 0.08 NTU.

The river water’s variability is one big challenge facing the TMWA, which serves about 400,000 residents of the Reno-Sparks area in northern Nevada. Another is a drought that has persisted for four years, putting stress on water supplies. On both counts, the utility’s 16-member operations team has come through, with lots of help from the rest of the 190-member staff and from customers who know the value of water in a high desert environment.

Most water heading to customers passes through conventional treatment at the 90 mgd (design) Chalk Bluff Water Treatment Facility. That plant, commissioned in 1994, received a 2015 Presidents Award for excellence in water treatment from the Partnership for Safe Water.

Paul Miller, manager, operations and water quality, says the award is a natural outcome of his team’s dedication to quality. “It’s a tribute to the operators and a testament to their pursuit of excellence,” he says. “That pursuit of excellence is shared throughout the entire company.”

Newly expanded

The TMWA was formed in 2001. In January 2015, the utility completed a consolidation with the Washoe County Department of Water Resources and the South Truckee Meadows General Improvement District. The merger aimed to reduce the cost of service and to maximize use of surface water resources across the region.

During non-drought years, the TMWA draws about 90 percent of its water from the Truckee River and the rest from 92 groundwater wells. Demand averages about 62.5 mgd but can peak at 125 mgd in summer. At such times, the utility calls on its 27 mgd (design) Glendale Water Treatment Facility.

“During periods of drought such as this, we rely much more heavily on groundwater,” says Miller. “We have a drought plan that we are following, and everything is going according to plan. The best thing for this community is that we have stored surface water upstream in a number of reservoirs. We have used about 20 percent of that stored water during this drought. We’ve also asked our customers for a voluntary 10 percent reduction in usage. They have responded even better than we’ve requested.”

All members of the operations team are dual-certified, licensed in treatment and distribution. Foremen are required to have Grade 4 certifications; all operators are certified to Grade 3.

The team includes:

• Will Raymond, water operations supervisor
• Working foremen Tim Flanagan, Pat Kuykendall, Brian Luczkow and Ted Saxe
• Treatment plant operators III Kurtis Arnold, Mike Bryant, Travis Bunkowski, Darrin Garland, Ben Goodrich, Bill Hovda, Jeremy Keele, Scott Knecht, Michael Nevarez and Jimmy Winters (James Bryant is an apprentice operator)

River’s challenges

Operating the Chalk Bluff plant means constantly watching raw water quality. The Truckee River flows out of Lake Tahoe and drains part of the high Sierra Nevadas. “You can imagine flowing from a mountain watershed with snow melt, how variable the raw water can be,” says operator Knecht. “We get heavy thunderstorms in spring, and we have a fire-scarred watershed.

“Combine those two and you can get huge runoffs very quickly. We get some seriously dirty water. In minutes, we can go from 2 NTU up to 5,000 NTU — that’s like thick chocolate milk. We continuously surveil the upstream watershed conditions for any problems coming down toward us so we can decide how to treat it, or even close the plant intakes and let the slug go by, if we can afford to. Usually, though, we treat the water.”

Seasonally low raw water temperatures and wide diurnal pH swings add to the treatment challenges. The pH, driven by algae, can exceed 9 in the early evening and bottom out below 7 in the early morning. Despite all this, the imperative is to produce water that never exceeds 0.08 NTU.

Treating with precision

Water comes to the Chalk Bluff plant in a 6 1/2-mile concrete-lined canal and passes through coarse screens before entering two 2-million-gallon pretreatment ponds. Although their main purpose is gravity settling, the ponds can be chlorinated to oxidize taste and odor (which can be caused by algae blooms in the river) or fed primary coagulant to speed settling (such as when the raw water is extremely turbid).

The water then passes through a pair of Envirex and Link-Belt fine, mechanically cleaned screens (WSG & Solutions) and is dosed with carbon dioxide as needed to bring the pH below 7.7. Next, the water enters two treatment trains where polyaluminum chloride coagulant is added. After flash mixing, the flow enters six flocculation/sedimentation basins. These are followed by 12 gravity filters containing 54 inches of anthracite and 10 inches of silica sand media, and licensed for a loading rate up to 8 1/2 gallons per square foot per minute.

The filtered water is disinfected with sodium hypochlorite to achieve an overall 4-log pathogen removal/inactivation, then adjusted to pH 8 with soda ash before distribution to minimize potential leaching of copper and lead from customer piping.

Fine tuning

A variety of measures helps ensure that water leaving the filters stays below 0.08 NTU. “We have turbidimeters (Hach) a few miles upriver so we can watch a plume of dirty water come down toward us,” Knecht says. “In the raw water canal, we have cameras and turbidimeters. Then we have turbidimeters throughout the plant, all the way through the process. We adjust our feed rates based on turbidity and flow, the temperature of the water, and the type of dirt that’s in it, whether it’s large or small, easy to treat or not.”

Coagulant addition is flow-paced; jar tests also support dose determination. “We continuously change the dose, anywhere from 14 to 30 mg/L,” says Knecht. “It’s automated based on how much water is coming into the plant, as read by the flowmeters. Each metering pump is checked at least twice a day for accuracy to make sure those pumps are giving us exactly what we want.”

Two streaming current detectors (Milton Roy) help operators regulate the coagulant feed rate and optimize flocculation and sedimentation. But pure operator observation helps, too.

“Through experience, you can tell by the color how big or small the particles are and how easily they’re going to settle,” says Knecht. “We look at the floc continuously. When we have good treatment, it looks much like storm clouds and it goes right to the bottom of the sedimentation basin.”

A Zeta potential analyzer (Brookhaven Instruments, a Nova Instruments Company) can be used to measure the electrical potential of particles in the water to help assess how well the primary coagulant is working.

To deal with extremely cold water, operators can add anionic and non-ionic polymers to aid coagulation and flocculation, or reduce the filter loading rate. A final line of defense is a fail-safe mechanism on the filters. If a turbidimeter on a filter detects turbidity rising toward the limit of 0.08 NTU, the effluent valve closes, a waste valve automatically opens, and the water is returned to the primary settling ponds while the issue is diagnosed and resolved.

A SCADA system with Wonderware software (Schneider Electric - Invensys) with some 7,500 inputs oversees the distribution system and more than 90 storage tanks. Each day, the SCADA system distills flow data into a production number and a consumption number that, along with the weather forecast, helps the staff set the next day’s production.

“We’re on a fine tightrope,” Knecht says. “We’re using our drought resources stored upstream, and we have to husband those resources carefully. So our production/consumption numbers are critical for our planning. We don’t have any water to waste. We need to plan how much we’re going to make the next day.”

Quality first

The TMWA’s focus on quality made pursuit of the Presidents Award natural, according to Miller: “We decided it was just the best a utility could do to protect public health and the best water we could offer to our customers, so we embraced the goal.

“We talked to the members of our firm and said, ‘Look, we’re going to embrace this and go the whole way with it.’ I’m glad we did. I’m not an award-seeking individual, but it was a good goal for the utility. It’s a good goal for any utility to try to achieve. When we received the award, I believe only 18 other utilities had won it. You wouldn’t achieve this without having a committed team of people. It took an operations team fully on board to achieve this high standard (0.08 NTU) 100 percent of the time. They made it happen through some really challenging conditions over the last several years.”

Knecht observes, “For the 14 years I’ve been with this company, every operator or apprentice has been really inculcated with the fact that water quality is job one. Yes, we try to do it in a fiscally responsible manner, but we simply don’t cut corners when it comes to water quality. I’m sure everybody who works at TMWA feels the same. But as operators, we’re on the front lines. It’s ingrained in us that water quality will not be sacrificed for anything.”

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Tomorrow’s operators

The Truckee Meadows Water Authority helps fill the pipeline for water operators through a state-certified apprenticeship program, in cooperation with the International Brotherhood of Electrical Workers union.

“We put candidates through a two-year program that includes the Sacramento State University curriculum,” says Scott Knecht, operator III. “There are numerous milestones of achievement to be met each month. Work hours are aligned to the different disciplines in water treatment and distribution.

“All the hours are carefully calculated and recorded to enable participants to qualify for state certification. There are milestone tests that each apprentice has to take and pass. It’s a very rigorous program.” Apprentices rotate through day and night shifts and among four crews, gaining exposure to all facets of the processes.

“After the two years, they should have their Grade 2 state treatment and distribution licenses and be ready to go to work,” Knecht says.

Openings for apprentices attract multiple applicants, from high school graduates on up to people with bachelor’s and master’s degrees in a variety of fields, says Knecht. “We look for people who want more than just a job. It takes a big commitment to make it work, but it’s worthwhile. It’s satisfying, it’s a great career, and it’s a great company.”