Change in Culture

Mesa moves past reactive thinking and shifts focus to efficiency, infrastructure investment and a healthy future.
Change in Culture
City of Mesa Water Resources Director Dan Cleavenger (right) looks on as a crew replaces a 12-inch water valve along a residential street in Mesa. (Photography by Mark Henle)

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Rapidly growing urban development. Sharp increases in the demand for freshwater. It’s a double whammy that most municipalities would just as soon avoid.

But not Mesa, Ariz. The Mesa Water Resources Department (MWRD) has not only accepted these challenges, but is succeeding — to the point that the utility received a coveted Gold Award for Exceptional Utility Performance from the Association of Metropolitan Water Agencies (AMWA) at its annual meeting last fall. With responsibilities for both drinking water and wastewater, Mesa was honored for its record of recycling, cost control, infrastructure integrity and performance metrics.

MWRD Director Dan Cleavenger attributes the success to a change in culture.

“We’re proactive in how we go about the issue of aging infrastructure,” he says. “Through the use of performance metrics [see sidebar], everybody becomes more involved in the decision-making, and everyone is more accountable.”

A comprehensive monthly report that incorporates MWRD’s metrics and promotes openness and inclusion reinforces inter-staff communication. Issued electronically, the report follows a template and includes charts and graphs that track the utility’s performance. “We post it at the end of every month, and everybody can see what everyone else is doing,” Cleavenger says.

He says the approach results in a more transparent operation. “We’re especially open and honest with what our spending is and what our needs are,” he says. “In return, our city council has been very supportive.”

The utility

Located just southeast of Phoenix, Mesa has a population of nearly 500,000 — making it the third largest city in Arizona, and 38th largest in the United States. The MWRD serves customers in a 170-square-mile area, and has been providing drinking water, and treatment and recycling wastewater for over 100 years.

The utility owns and operates the Brown Road water treatment plant, capacity 72 million gallons per day, which treats Colorado River water from the Central Arizona Project. A second treatment facility – the Val Vista plant – is jointly managed by Mesa along with the City of Phoenix, and treats water from the Salt River Project. Capacity is 220 mgd, with Phoenix using about 130 mgd.

Treatment processes at both plants are similar.

In late summer and fall, the plants use powdered activated carbon to remove taste and odor caused by decomposition of organic matter in the raw water source. Chlorine dioxide – generated on site – is used for both pre- and post-treatment disinfection.

Alum addition promotes flocculation and sedimentation in a ballasted Actiflo process (Veolia Water). Clear water then passes through multimedia filters of sand and anthracite; filtered backwash water is returned to the raw water supply.  

The product water is fluoridated before being pumped to storage reservoirs and then by gravity or pumping to customers.

At the Val Vista plant, granular activated carbon is used to control disinfection byproducts.

Wastewater returns through a 1,600-mile sewer system to a series of three water reclamation plants, two owned outright by Mesa, and the third shared with the communities of Queen Creek and Gilbert.

The Northwest Water Reclamation Plant has a capacity of 18 mgd, and uses screening and grinding, primary sedimentation, biological treatment and nutrient removal, final filtration and disinfection. The effluent is discharged to two recharge sites and the Salt River, which also recharges the aquifer.

The Southeast Water Reclamation Plant is designed to handle up to 8 mgd, using a process flow similar to the Northwest plant. Treated water is used for golf course irrigation, pond replenishment and agricultural irrigation.

The jointly-owned Greenfield Water Reclamation Plant is designed for 16 mgd, and is an expansion of a former lift station. Treated water is pumped directly to the Town of Gilbert’s recharge facilities and to the Gila River Indian Community through an intergovernmental agreement for beneficial reuse in agriculture. Mesa is also part-owner of the 91st Avenue Wastewater Treatment Plant with the cities of Phoenix, Scottsdale, Glendale and Tempe. 91st Avenue delivers reclaimed water to the Palo Verde Nuclear Generating Station.

Biosolids from the reclamation plants are digested, thickened and dewatered by centrifuges. Cake is land-applied throughout the area.

Saving money for ratepayers

The Gold Award from the AMWA made specific mention of two accomplishments by the MWRD – per capita operating costs that are 30 percent lower than the national average, and a pipe break and leakage rate that is 90 percent below the average.

How do they do that? 

Like all water and wastewater treatment facilities, Mesa’s systems consume a lot of electricity, so the emphasis has been on reducing energy use and cost wherever possible.

The department’s SCADA system is a big help, monitoring and controlling pump stations, and managing the water distribution system and storage reservoirs for energy savings. “We try to run equipment at off-peak hours as much as possible,” says MWRD Assistant Director Carlos Padilla. “We’re getting better and better at it.”

Efficient pumping is a major goal. Padilla says the MWRD is constantly monitoring pump performance at its well sites, pump stations and distribution system. Older models are replaced with high-efficiency pumps whenever and wherever necessary. For instance, at three of Mesa’s largest pump stations, higher efficiency pumps resulted in electrical cost savings of 15 percent.

Energy consumption is also on the radar screen at the treatment plants. Padilla points out that at one of the reclamation plants, digester methane gas is captured and used as fuel for cogeneration. “We generate enough gas to power one of the process buildings, and also to heat the digesters,” he says. The savings average $5,500 per month.

For dewatering, Mesa uses centrifuges – large consumers of energy – so the staff now operates the centrifuges during off-peak hours. “We try to shave as much high-peak energy use as possible,” says Padilla. At the Greenfield Water Reclamation Plant, operating the dewatering centrifuges during off-peak periods has resulted in electrical cost savings of 55 percent.

Other energy saving modifications include replacing coarse bubble aeration with fine bubble in the aeration basins at the water reclamation plants, and a shift from single stage to high-speed blowers. The changes have saved from 50 to 70 percent in energy consumption. In the ultraviolet light disinfection process, a move from medium-pressure bulbs to low-pressure, high-energy bulbs has resulted in operational cost savings of 30 to 40 percent, notes Arif Rahman, deputy engineer.

Repairing the pipes

Mesa is among the U.S. cities and utilities taking the matter of aging infrastructure into their own hands. According to Jake West, deputy director of distribution and collections, the investment in new infrastructure is paying off.

“We’ve invested money in more reliable pipe,” he says of MWRD’s sterling record of reducing pipe breaks and leaks. “We’re doing a better job on leaks.”

Communications and transparency again have been the key to the progress. Cleavenger says the utility has participated in strategic infrastructure planning with the Mesa City Council. “We looked at our mains, and earmarked all that were 30 years old or older.”

Based on that analysis, he says, MWRD was able to start on a cycle of replacement.

“We’ve been tracking water main breaks and leaks since 1999, and have developed a good database that identifies the year the pipes were installed and the type of pipe, as well as the break characteristics in certain sections,” West says. “Then we prioritize and replace as needed as we go forward.”

Water and wastewater piping underneath heavily traveled roads and intersections gets special attention in the analysis. “If a freeway or interchange is being built and we have identified a future need in our master plan, we insert sleeves under the roadway rather than have to dig it up in the future,” West says. He adds that his team works closely with the city’s transportation department to identify older pipelines under roads ticketed for future improvement, programming the pipes for replacement as part of the road work.

Mesa uses pipe relining in some sections. “We started using the technology a couple of years ago,” West says. “We had a 30-inch interceptor collapse, so we did 5 miles of CIPP.”

The MWRD uses other rehab methods like sliplining and pipe bursting to do spot repairs throughout the system and at intersections where pipe conditions lend themselves to the use of such technology. Mesa’s largest relining project to date consists of sliplining approximately 2,400 feet of HPDE liner inside an existing 42-inch prestressed concrete cylinder pipe feeding a 10 mgd reservoir.

Still, West says, leaks and breaks can’t be entirely eliminated. Mesa uses about 400 Permalogger acoustic leak detectors and conducts leak surveys, patrolling the system regularly with a part-time employee who follows up on “hits” and files a service order. “We want to get to the leaks before they get to the surface,” West says.

On the sewer side, West and his team have developed a comprehensive protocol that has helped them meet – and beat – the goal of no more than 16 SSOs per year.

“Our five-year plan is to clean 20 percent of the system – 320 miles – every year,” West says. Mesa uses four combination jet/vac units (Vactor and Camel by Super Products) and one CCTV truck. The utility contracts some of the larger pipe work out to the local firm of Pro-Pipe. “We’re getting there,” West says. “We’re pretty close to our annual average.”

West notes that, over the last few years, the number of systemwide SSOs has averaged about eight per year – a credit to the cleaning and inspection plan, but also to close cooperation between the collections crew and Mesa’s industrial pretreatment program. “When we have an issue with heavy concentrations of grease or fats, we work with the IPT [Industrial Pretreatment] group and get our FOG [fats, oils and grease] brochure out to the people involved,” West says. “We stop by to talk with them.”

The future

Mesa continues to grow. Already larger than U.S. central cities like Atlanta, Pittsburgh and Minneapolis, Mesa is experiencing rapid industrial development in its southeast sector — fueled by new and expanding high tech and digital businesses.

More infrastructure will be necessary.

“We have huge needs there,” Cleavenger says of the southeast part of his service area. “We’re building a high tech corridor. We’ve just had an Apple plant move in and other big names are coming our way.”

Cleavenger envisions at least one new water treatment plant and a major expansion of one of the water reclamation plants – an estimated total investment of some $500 million in the next four to five years. He says the city will probably be looking at membrane bioreactor technology as part of the reclamation plant expansion.

“We need to get ourselves in shape and be ready for the necessary infrastructure,” he says as a sort of personal reminder as well as a departmental challenge.

But he quickly adds, “We’ve done the things in the past that have allowed us to get to where we are. We have a solid foundation to build upon.”


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