City Water Departments Answer Five Common Questions

By Warren Tenney

Your city’s water department does a great job using science and engineering, muscle and skill to get drinking water into your home 24 hours a day, seven days a week. The water professionals at your city can answer your questions about water quality testing, water rates and billing, the efficient use of water, free water conservation classes, water conservation rebates, and water leaks in the street. But there are things they can’t do, such as fix your plumbing or chill your water before it reaches your home. We called the people who answer the phone at city water departments and asked them to share a few of the most frequent questions they get from customers. Here they are:

1. Why does warm water come out of my cold faucet? This is, of course, a popular call when summer temperatures are peaking. Your water department cannot make the water coming into your kitchen or bathroom colder or hotter. Water distributed by your city comes to your house and up to your water meter through pipes buried 12 inches to 18 inches below ground. If temperatures are particularly hot, the ground is not cool at that depth. (If you are from a place with cold, hard winters, perhaps Connecticut or Minnesota, water pipes are buried 42 inches below the surface to prevent them from freezing.) From the water meter, the water coming into your house enters through a line (usually under your front yard) and then through an exposed pipe. Water has plenty of time to warm up before it gets to your kitchen or bathroom sink. You may want to keep a pitcher of cold water in your refrigerator for those summer days.

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2. Why does my water smell? There are times when you turn on a faucet and get a whiff of a sewer or rotten egg smell. Look under your sink and you’ll see a pipe shaped like a U. This is called the P-trap (because from a plumber’s angle, when it’s attached to another pipe, it looks like the letter P). It serves two purposes. First, if hair or food creates a clog, this is where it will happen – a place accessible to plumbers, instead of deep within your plumbing system where it would be tougher and more expensive to reach. Second, about a cup of water always sits in that P-Trap and serves as a barrier that keeps sewer smells from entering your home. The barrier can fail and develop gaps when the water in this pipe develops a thick layer of scum from hair or food. Sometimes the barrier fails because the water in the P-trap dries up, such as when you go on vacation or fail to use the guest bathroom for weeks. It’s likely to happen more often when the air conditioner is running and drawing the moisture out of the air in your home. When you run the water, it agitates whatever is in – or not in – the P-Trap, creating that whiff of sewer smell. Run the water occasionally in all of your sinks and, when on vacation, ask the person who is watching your house to run the water in your sinks. If the smell persists, clean your drains or call a plumber.

3. Why is my water cloudy? Air bubbles in the line can make your water cloudy. Sometimes it happens when your water department is flushing out fire hydrants in your neighborhood or when a plumber has been to your home. Run the water for a little while or let the water in your drinking glass settle. It will clear up.

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4. Why is water bubbling up from under my yard? It is your responsibility to identify and correct plumbing issues on your side of the water meter, which is most often located in your front yard near the street. Your responsibility includes the water line buried in the yard that leads to your plumbing and irrigation systems. If water is bubbling up anywhere in your yard, it’s most likely an irrigation line that has been leaking for a while. It’s time to call an irrigation systems professional or to make time for a little do-it-yourself project. It can be costly to ignore your irrigation system. Know where the main irrigation lines are buried in your yard and run the system occasionally when you have time to walk your yard and look for leaks. AMWUA’s Smart Home Water Guide can help you find and fix irrigation leaks.

5. Why is my water pressure low? The State requires cities to provide water at a minimum of 20 pounds per square inch (psi).  (Some individual cities have set their minimum pressure higher than 20 psi.) Getting higher water pressure can sometimes be physically hard to achieve. A water department employee can gauge the water pressure for you as it is coming into your home from the city service line to your meter. If the city employee finds that the water entering your meter is at an acceptable pressure then the problem is within your own plumbing system. A broken pipe or a clogged filter in your water softener can reduce your water pressure. It’s time to call a plumber.

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

On The Job: Skill, Hard Work Ensures Water Gets To Your Home

By Warren Tenney

When someone asks Sal Correa what he does for a living, he answers this way: “You know the water you drink? I make sure it gets to your house.” That’s a pretty good description. Sal co-leads a 7-member City of Chandler team that replaces aging water distribution pipes, repairs breaks, and installs fire hydrants and new water meters. Sometimes his crew lays water lines to new subdivisions.

Sal is a Lead Utility Systems Technician who organizes his crew’s workload and talks to Chandler residents about the work being done on their streets. He drives backhoes, digs holes and wields pipe-cutting saws. “I get muddy,” Sal said. “I like what I do.”

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Each day, Sal walks into work at 5:30 a.m. ready to coordinate each job with Chandler’s traffic and police departments. There is always something that must be done to secure the 1,230 miles of pipes in the city’s water distribution system. He orders equipment that may be needed from vendors and calls Arizona Blue Stake, which maps underground utility lines and helps prevent workers from disturbing other underground lines, such as electric or gas. If a job means Chandler residents will lose their water for a while, Sal makes sure they are notified within 24 to 78 hours in advance.

Sal’s first priorities are emergency breaks. Some can be underground breaks that fracture a length of pipe and send water seeping up through crevices in the street and sidewalks. Neighbors lose water pressure and dirty water comes out of their faucets and they call the department. Sometimes these breaks are more spectacular and blow out a hole in a main pipe sending water gushing 30-feet in the air. These types of emergency breaks are the hardest. Traffic must be redirected, the leak brought under control, and the break tracked down – even before unhappy customers are notified about why they suddenly have no water and how long they will be without it.

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Sal said most breaks – even large ones – can be fixed within three to six hours. Neighbors are always given a window of time that accounts for unforeseen problems, such as a fix that may not hold or trouble tracking an entire break. Most of the time Sal and his crew can finish well within the window, making customers happy again.

Replacing aging water lines and fixing breaks and repairs can mean working in a hole 3 feet deep or 7 feet deep. Anything below 5 feet requires the crew to shore the walls with an aluminum brace to prevent the hole from collapsing. Sal and his team members enter and exit the hole using a ladder attached to the shoring. Everyone shares the hardest parts of the job, the digging and pipe cutting, so one member of the crew is always resting while another is working. (That’s why residents often see one or two workers watching, while one is working.) During the hottest summer days, Sal makes sure members of his team use a canopy for shade and that each member works in short spurts. When Sal suspects a member of his crew is getting overheated, he’ll send him into a city vehicle to cool down in the air conditioning.

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Nine years ago Sal was cutting a pipe with a 12-inch-blade motorized saw, a job he had done hundreds of times. This time the pipe dropped and pinched the end of the blade, which suddenly kicked back and pinned Sal to the wall of the hole. The blade cut deeply into Sal’s mouth, causing damage that required two surgeries and numerous root canals. The accident left him with a thin scar from his lip to his chin that is just visible through his short-cropped beard. He went back to cutting pipe in those street holes as soon as possible. “After I got back in there, my coworkers said, ‘You’re not allowed to touch saws anymore, get out of there’,” Sal remembers.  He admits the first cutting job after the accident was a little terrifying. “I tried not to show it, but yes, it was.” Since that accident Sal said he has cut thousands of pipes. 

In 2001, Sal sold everything he had and followed his wife’s parents from Chicago to Arizona. Sal wanted more opportunity for himself and his wife, Gladys, and a good place to raise their 5-year-old son. Sal started working for Chandler as a meter reader. He took courses to be certified as a Utility Service Operator I and II in the water distribution department and was then promoted to crew leader. Sal’s son, Damien, attended Northern Arizona University on an academic scholarship, just graduated with a pre-med degree, and is waiting to hear from the medical schools where he applied for acceptance.

Damien’s academic pursuits left Sal and Gladys at home with Bella the Boxer and two toy Yorkshire Terriers, Blu and Jax. Sal gets home by 4 p.m. every night and has dinner made by the time his wife, a health care administrator, arrives home. Late last year, the couple joined a neighborhood co-ed kickball team.

Sal is tough when it comes to his job, but gets a little teary-eyed when he talks about the parents and the seven siblings – including a twin – he left behind in Chicago. He is the youngest, visits the city twice a year and still misses them. One sibling has just moved to California. He hopes more family will move west, because Sal said he’s staying in Arizona’s sunshine.

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org

Partnership Makes Desert Golf Courses Sustainable

By Warren Tenney

Since 1998, the City of Scottsdale has been treating about half of its wastewater to near drinking water standards. It’s an expensive process that uses reverse osmosis technology, but the city isn’t paying for all of it. The cost to build and operate the plant is shared between Scottsdale and 23 private north Scottsdale golf courses that use the water to keep their greens pristine.

It’s more difficult to keep golf courses green when irrigation water has a high salt content.  Saltier water means watering the greens more often and using more fertilizer. Before building the Advanced Water Treatment (AWT) Facility, the golf courses used untreated or “raw” Colorado River water delivered to the city by Central Arizona Project. The raw water has a salt content of about 600 to 650 milligrams per liter (mg/l). Wastewater recycled at the Advanced Water Treatment Facility is blended with raw CAP water and yields water with a sodium concentration below 125 mg/l, a level required to fulfill the city’s agreement with the golf courses. Using this low-salinity recycled water means the courses can use less water and fertilizer to maintain higher-quality greens. It also means the city can save more raw water to treat for drinking.

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Ozone piping at Scottsdale’s Advanced Water Treatment Facility

The water that flows out of your home from your sink, shower, toilets and laundry and into the sewage system is traditionally called wastewater. The name no longer really applies for AMWUA cities. Nearly 100 percent of what was once wasted effluent is treated by the cities and put back to use.  In other words, water is reused.  Treated wastewater from five AMWUA cities – including the other half of Scottsdale’s wastewater – is sent through a 36-mile pipe to cool the Palo Verde Nuclear Generating Station. Cities also use treated wastewater to irrigate parks, create fishing lakes and wetlands, or save underground for future use, which is called “recharging” the aquifers. Wastewater is now a renewable water source, most often called recycled water or reclaimed water.

All reclaimed water used in parks, golf courses, HOA common areas, school playgrounds or church campuses is treated to what the state deems as A+ quality. Grade A quality means the water is treated and disinfected until there are no routine, detectable disease-causing bacteria. It moves up to A+ when the treatment process also removes nitrogen compounds, which can contaminate groundwater. Scottsdale’s advanced treatment plant goes one giant step further. It uses reverse osmosis to remove mainly salts and inorganic materials from the recycled water produced at the plant.

Wastewater always has a high salt content because it passes through homes and businesses, picking up salt from cooling towers, food and other waste. Chemicals used to treat wastewater also add salt to the end product. The salinity of Scottsdale’s wastewater from homes in the northern part of the city is particularly high, around 1,100 milligrams per liter. Scottsdale estimates that water softeners account for more than 30 percent of the total salt concentration in the wastewater system. Water softeners work by exchanging salt for hard minerals, such as calcium and magnesium, creating soft water for homeowners but dumping the salty brine discharge into the sewer system.

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Water not used by Golf Courses is saved underground via a recharge well like this one.   Photos: City of Scottsdale

The advanced treatment plant is capable of producing 20 million gallons a day of low-salinity recycled water, although current rates of wastewater flowing into the plant are closer to 10 million gallons. In the summer, the golf courses use all of that water. When temperatures climb into the 110-degree range and above, recycled water is supplemented with raw water to meet summer irrigation demands. During winter months, the golf courses typically need an average of only 3 to 5 million gallons per day and, after a few rainy days, that need may drop to zero. Any additional low-salinity water produced at the plant is saved underground at the Scottsdale Water Campus for future use. Scottsdale also uses ozone and UV treatments on the water it saves underground to recharge the aquifer. These processes remove “emerging contaminants,” which are contaminants the U.S. Environmental Protection Agency is studying, but has not yet regulated. 

Scottsdale wanted to support its golf economy, but not use its precious drinking water supplies for irrigation. The dilemma was solved nearly two decades ago by a public-private partnership and technology. Today they call that innovation. Twenty years ago, it was just smart.

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

On The Job: Water Treatment Supervisor Uses Brains, Heart And A Little Muscle

By Warren Tenney

Luiza Yordanova appreciates the Valley’s winter weather as much as we all do but winter makes her job as supervisor of a City of Tempe drinking water treatment plant a bit more complicated. She sat down on a beautiful day earlier this winter to explain why.

In the winter, the Johnny G. Martinez Treatment Plant gets raw water from the Verde River instead of its summer mix of water from the Salt and Verde rivers. The cooler temperatures and the switch to predominantly Verde River water means Luiza and her team need to readjust chemicals and treatment processes to maintain drinking water standards.

Luiza’s plant also was the sole provider of water to businesses and residents because Tempe’s second drinking water plant was shut down for its routine annual maintenance. Luiza’s plant shuts down for annual maintenance in January  and devising a schedule to squeeze in all the work she wanted to accomplish was keeping her up at night.

Luiza also was waiting for a new piece of plant equipment to be delivered and a crew of workers were installing solar panels on the roof of the plant’s water reservoir to provide alternative power. She also had just finished writing a presentation about “enhanced coagulation” that she submitted to this year’s AZ Water Association conference. If accepted, it would be her third presentation at the conference. Luiza called her work as a Plant Supervisor “a beautiful job with beautiful people.”

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Luiza supervises 10 people – plant operators, electricians, mechanics and technicians. Every morning begins the same way: checking on the quality of water being distributed by the plant via the technology available on her computer. Then, at 6:55 a.m. she’s opening the door of the control room where she visits with the midnight operator and the over night crew and welcomes the arriving day-shift crew. They talk together about the quality of the water the plant is producing and maintenance needed on the plant’s equipment. “Communications with technicians, all the trade groups, with the operator, it’s my key,” Luiza said.

On this particular day, “finish water pump” number five had a maintenance problem withluiza-jgm its couplings and seals. It also looked as if pump six would need maintenance at least on its couplings. The plant has eight pumps. This redundancy allows for continual repair and maintenance while drinking water is always being pumped for distribution 24 hours a day every day. Maintenance of the equipment is one of Luiza and her crew’s top responsibilities.

“Equipment runs the plant but operators monitor the equipment, so this is my major job,” Luiza said. She also is responsible for managing people, keeping inventory, ordering chemicals, and ensuring the process used to treat the water is producing safe, reliable drinking water for Tempe homes and businesses. To get it right, Luiza depends on her team members. She spends 80 percent of her time on the floor talking with her crew and sometimes helps them with their jobs.

“It’s not because I have to, it’s because I choose to,” Luiza said. “I choose to because, for me, talking to people and learning the problems from them and thinking about their solutions gives me more opinions. They work around the equipment more than I do, so they can be useful.”

Luiza also uses the time to monitor her staff members and make sure they are concentrating on work and not problems at home, such as a sick child. Luiza can’t afford distracted employees in a water treatment plant and sends her employees home until they can come back ready to concentrate on the job at hand. “This is part of my understanding of leadership,” she said.

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Luiza, 54, explained all this while gently rolling her Rs. She and her accent are from Bulgaria where she managed the country’s largest cement manufacturing plant in Devnya for 19 years. The plant also ran the water and wastewater treatment plant for the city. Luiza is a chemical engineer and is studying to become a certified professional engineer in the United States. It’s simply a matter of learning new technical terms, she said.

Moving to the United States from a country and a job she loved happened quickly for Luiza. It began in January 2005 while exchanging information with a retired Oregon engineer on LinkedIn about industrial materials used in the production of cement. She invited him to visit her cement factory in May 2005 and he accepted. That’s when Luiza said their conversation “veered away from cement.” After several more trips and by January 2006 the divorced mother of a grown daughter was in the United States, married to her engineer from Oregon and looking for a job. She spent time as a quality control manager at a Midwest cement manufacturing plant that closed down and the City of Tempe hired her in 2010 as a water treatment plant operator.

Luiza lives in the City of Chandler. She grew up along the Black Sea and enjoys traveling to beaches on both the west and east coasts. She hikes, plays a mean game of chess and her husband got her hooked on novels about detectives who solve crimes using science. As an afterthought Luiza mentioned she speaks four languages – Bulgarian, Russian, English and German. “I started learning Italian but I’m thinking of switching to Spanish,” she said. “I like Italian pronunciation but I think Spanish is more useful here.”

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

Sen. John Kyl: Compromise Is Key To Water Leadership

By Warren Tenney

This month, former Senator Jon Kyl told a gathering of elected officials and water professionals that Arizona’s past water successes had one thing in common: the willingness of competing forces to compromise for the good of the state. Now, Senator Kyl said, it is time we do it again.

Senator Kyl is a water lawyer who represented Arizona’s citizens for 25 years, first in the U.S. House and then the Senate. He was the guest of honor at an Arizona Water Reception, which brought together state legislators, mayors, city council members and others to highlight the importance of water issues for state leaders. The reception was held in downtown Phoenix and hosted by AMWUA with the help of nine sponsors.

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City of Goodyear Councilmember Joanne Osborne, a member of AMWUA’s Board of Directors, arrives at the Arizona Water Reception. Sen. Jon Kyl (right) was guest of honor. 

Arizona’s legacy of resolving difficult water issues offers a template to help solve today’s challenges, Senator Kyl said. Speaking of this tradition, he said that by “ making compromises for the good of the state – in a non-partisan way – we avoided those challenges becoming crises.” He pointed out some examples of compromises that solved big water challenges for Arizona.

  • Salt River Project. More than 100 years ago, Arizona farmers and ranchers from Mesa to Avondale agreed to offer their land as collateral to finance a federal loan to build Roosevelt Dam. Roosevelt Lake and a series of smaller reservoirs and canals became the largest source of water for the Phoenix Metro area. Salt River Project (SRP) operates the system to this day.
  • Central Arizona Project. After World War II, Arizona needed to bring its share of the Colorado River to Central Arizona, where its population was booming. Taking the water required an agreement among neighboring states, in particular California, before the federal government would agree to finance and build a 360-mile canal to transport the river’s water to central Arizona. Today, the Central Arizona Project (CAP) provides almost 40 percent of the water used by the AMWUA cities.
  • Groundwater Management Act. The 1980 Groundwater Management Act regulated and slowed the pumping of groundwater that was drawing down aquifers in the state’s most populous areas. The Act was the result of rancorous but successful negotiations among cities, mining companies, and agriculture, as documented in Groundwater: To Enact a Law for the Common Good, a documentary screened during the Water Reception.

Among the most pressing unresolved issues facing the state right now are falling water tables in some rural communities, Senator Kyl said. The Groundwater Management Act does not regulate groundwater pumping  in rural areas of the state as tightly as it does in urban areas.  Now, conflicts are brewing in many rural communities over new wells and decreasing water levels in underground aquifers.

 The state must also resolve the question of who has the right to use the state’s surface water supplies.  This seemingly simple question has been the source of litigation in the state for the last 40 years in a complex court case involving tens of thousands of parties in what is known as the “General Stream Adjudication.” This case complicates Arizona water policy because it makes it nearly impossible for thousands of water users to have legal assurance regarding their water rights.

In the context of his remarks about eventually resolving the General Stream Adjudication, Senator Kyl said that in the course of his public service he has learned that proposed solutions do not last if there are winners and losers. All sides must win at least 80 percent of what they want to create a successful and lasting resolution. When it comes to resolving the General Stream Adjudication, that may mean finding additional sources of water through augmentation and recognizing the impact of the Adjudication on small water users, Senator Kyl said.

Solutions to these complex problems depend on data collection, analysis and oversight by the Arizona Department of Water Resources (ADWR). Speaking to Legislators in the audience about the importance of ADWR, Senator Kyl said: “Whatever they need, make sure they have it because their technical work is essential to the resolution of all these disputes.” He also remarked that in his view, ADWR is the number one economic development agency of the state. He observed that investors and businesses want to invest in a community that has a firm water supply in place.

Senator Kyl said he is optimistic that Arizona’s leaders will come together to overcome these and other water-related challenges.  This is particularly the case when he sees so many of Arizona’s leaders knowledgeable about water and eager to learn. “The thing is you got to have an open mind and you’re going to have to really think things through,” he told the gathering. “You have to have a sense of destiny in that these are big problems for the future of the state.” 

The Arizona Water Reception was another step toward bringing leaders together who can solve these big problems. Now, it’s everyone’s responsibility to keep elected officials working on solutions for the common good, so our grandchildren and their children, will know we also had the will to act – and to compromise – on their behalf.

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

Power Switch: Economics Driving New Energy for Moving Water

By Warren Tenney

In 2009, I was a new member of the Board overseeing the Central Arizona Project (CAP) and energy, not water, was the primary focus. I was surprised with my sudden immersion into the ins and outs of energy. Yet, there was a good reason for concentrating on energy.

As one of the largest energy users in the state, energy is crucial for CAP. CAP needs to pump water uphill from the Colorado River through the 336-mile canal that delivers water to cities, Native American communities, and farmers in Central Arizona and south to Tucson. Since the 1970s, nearly 90 percent of CAP’s primary energy source has been the Navajo Generating Station (NGS) in Page, Arizona near the Utah border. The plant is one of the country’s largest coal-fired power plants.

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So in 2009 and 2010, the U.S. Environmental Protection Agency pushed hard to reduce the haze NGS produced in the scenic Four Corners area. It was estimated that NGS would need over a billion dollars in capital investment to reduce nitrogen oxide emissions to EPA’s satisfaction. Many felt EPA’s unspoken aim was to shut down NGS. CAP and the Salt River Project (SRP), the operator and part owner of the plant, took this attack on NGS seriously.

It was frightening to think of NGS shutting down or being forced to take on huge capital costs to meet EPA’s regulatory demands. The rallying cry was that NGS was critical to make sure CAP had power to operate and to keep energy costs low. At the time, many prominent voices correctly observed that keeping NGS open was important to Arizona’s economy, particularly to the City of Page and the surrounding Navajo Nation. NGS also provided CAP with a key revenue source. CAP sells surplus energy produced by the plant and uses the revenue to repay the federal government the loan it made to finance the construction of the CAP.

A concerted effort was made to find a compromise that EPA would accept to keep NGS open until 2044.  To the relief of many, in July 2014 the EPA and owners of NGS reached an agreement that would lower the levels of nitrogen oxide emission and keep NGS open until 2044.

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Inside the Navajo Generating Station  Photos: CAP

So fast-forward three years to today.  Many of us who followed the NGS story since 2009 are surprised with the news that the owners of NGS voted to close the power plant at the end of 2019. What has caused the 180-degree turn in the effort to save NGS?

Pure economics is driving the decision. The utilities that own NGS now are dealing with a power plant that is significantly more expensive than other energy options. Natural gas prices have dropped to record lows to become a viable long-term and economical alternative to coal power. This means pursuing the regulatory upgrades that were part of the compromise with EPA are even less cost-effective today. However, even if EPA loosened its coal regulations, the energy industry is headed towards having natural gas generation as the fuel of choice for many years to come.

So what does this mean to Arizona and particularly the Valley cities that utilize CAP?

First and foremost, CAP will have access to the energy necessary to move water through the CAP system even without NGS. In recent years, CAP has been looking at alternatives to NGS to be prepared for what is now happening. CAP can easily buy energy from the open-market power grid. Based on today’s energy market, CAP’s power costs would actually be significantly lower. Energy costs on the open market are much less than the cost to generate power at the NGS. This means CAP’s pumping energy rate – charged to the Phoenix area cities and others CAP users – will decrease.  Again, this new economic reality of the energy market is much different than just seven years ago when we were worried that an NGS closure would mean higher costs for CAP and its customers. 

NGS has been a reliable energy source for CAP.  While going on the open energy market will mean lower costs today, CAP faces the new challenge of how to best utilize the right energy sources to take advantage of low-cost power alternatives.

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Central Arizona Project canal.

While the decision to close NGS is not the dire situation we assumed it would be in 2009 and 2010, the closure of NGS still remains an enormous challenge for the Navajo Nation, Hopi Tribe and the community of Page. NGS has been a primary economic driver and major employer. Assuming the Navajo Nation extends the existing land lease for the plant through the end of 2019, the plant’s owners should have time to explore ideas to lessen the negative impact to that region.

The decision of the utility owners to close NGS – and the challenges it creates – reemphasizes the critical nexus between water and energy.

Warren Tenney was elected twice to serve as a member of the Central Arizona Project (also called the Central Arizona Water Conservation District or CAWCD) Board from Pima County. He served as Vice-President of the Board and as Chairman of the Board’s Finance, Audit & Power Committee. He resigned his board position in January 2016 to become Arizona Municipal Water User Association’s executive director.

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org

Wastewater Treatment Plant Turns Gaseous By-Product Into Profit

By Warren Tenney

Arizona’s largest wastewater treatment plant already cleans and re-uses nearly all of the waste it receives from 2.5 million people in five AMWUA cities. Now, the cities that own the treatment plant have found one more way to re-use its products. As of spring 2018, the 91st Avenue Wastewater Treatment Plant will stop burning off the mostly methane gas it creates as a by-product. Instead, the plant will transform the by-product into renewable biogas and sell it for more than $1.2 million a year.

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91st Avenue Wastewater Treatment Plant   Photos: City of Phoenix

The 91st Avenue Wastewater Treatment Plant’s effluent, or treated wastewater, is re-used to irrigate crops, create a wildlife wetlands project called Tres Rios, and provide cooling water for the Palo Verde Nuclear Generating Station, 36 miles west of the plant. The wastewater plant treats and transforms solid waste – all the stuff ground up in garbage disposals and flushed down toilets – into fertilizer for non-food crops, such as hay, alfalfa and cotton. The City of Phoenix, which operates the plant, and its four AMWUA city partners have found a way to produce yet another marketable product – biogas. Here’s how it will work.

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Tres Rios Wetlands

  • The plant has 16 large digester tanks with a capacity of 1.5 million gallons to 3 million gallons. These digesters operate like an industrial stomach, digesting solid sewage waste as a step toward turning it into fertilizer. Just like our own digestive system, these industrial digesters expel gas. That gas is now vented through three flares and burned off into the atmosphere.
  • Last week, Phoenix and its partners broke ground for a new facility next to the plant that is about as big as a football field. The new facility is being built and operated by Ameresco, a vendor selected by the cities that own the treatment plant. It is expected to be completed and operating by spring 2018. When completed, the plant will be fully automated and will be operated by one person. The stacks that flare the gas will remain on-site to act as a backup if needed.
  • The new facility will scrub and pressurize the plant’s gas into clean biogas. The gas will be compressed and travel through an underground pipe to a large commercial gas pipeline three miles west of the plant.
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This is a similar Ameresco bio-gas plant in San Antonio, Texas.

The 91st Avenue plant was built in 1968 by a partnership of AMWUA’s five original member cities, Glendale, Mesa, Phoenix, Scottsdale and Tempe. This partnership is known as the Sub-Regional Operating Group or SROG. The plant treats an average of 140 million gallons of wastewater a day but has the capacity to treat 230 million gallons. Both the plant and the biogas facility are built to accommodate what is expected to be a growing market.

For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.