Keeping it Local

El Paso delays expensive water importation by making water-saving, energy-reducing changes to its distribution and treatment systems.
Keeping it Local
Severo Borrego, left, water production assistant superintendent, with Salvador Vargas, Utility Central Control supervisor, monitoring the distribution system in Central Control.

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Located in the Chihuahuan Desert of Texas and facing a multi-year drought, the City of El Paso knows its local water sources eventually will fall short of demand. The 50-year plan for El Paso Water Utilities is to diversify its sources, which include importation.

To delay the need for costly imported water and to preserve existing resources, EPWU has a water conservation program that includes reducing leaks, a reclaimed-water program, an aggressive surface water treatment program, and an energy policy that cuts electrical use and operating costs.

To serve 211,000 water service connections, El Paso operates two water treatment plants with a combined 100 mgd capacity, sourced from the Rio Grande. These plants use conventional flocculation, sedimentation, filtration and chlorine treatment; one is experimenting with a final ozone-UV disinfection step. To diversify sources, the city has more than 100 wells with a total 142 mgd capacity. In 2007, the utility started a $91 million desalination plant to process the abundant brackish groundwater in the area.

During the hottest months, and during droughts, the surface water plants run at full capacity, and well water handles the excess. Since the desalination plant is costly to operate, the utility maximizes surface water before tapping the wells. In 2006, to comply with U.S. EPA standards, EPWU built a 30 mgd plant to remove naturally occurring arsenic from well water drawn from certain wells in the Mesilla aquifer.

To maintain the plants, the wells, 2,530 miles of distribution pipeline and 54 booster stations, the utility has a staff of 104 and a $30 million annual budget.

Leak reduction

El Paso sought to cut the waste of water and electricity by reducing leaks. A leak detection program launched in 2002 added more than 5,000 Permalog leak detectors (Fluid Conservation Systems) throughout the distribution system at a cost of $3 million, funded through the capital improvement budget. In 1995 the utility had been reporting 14 percent unbilled water, but three years after the leak detectors were installed, that rate fell to 8 percent, saving more than 80 million gallons and an estimated 355,200 kWh of electricity for treatment and pumping.

To upgrade the system further, in fall 2013 the utility plans to install new leak detectors that have longer battery life and produce fewer false positives. EPWU and U.S. Department of Interior Bureau of Reclamation will share the $160,000 budget.

Clamping down on power

In 2008, EPWU hired Manuel Perez as its first energy manager and enacted its first policy to adopt energy-saving practices. The utility worked with El Paso Electric Company, the local electric utility, to negotiate a time-of-use (TOU) rate that benefits both sides: The water utility pays less for electricity by reducing its electric energy use, and the electric utility reduces its system peak demand, delaying the cost of new generation.

“The water utility is one of the largest energy users in the city, so we identified ways to reduce our electric demand during peak periods for the utility,” Perez says. “The TOU rate provides incentives to reduce peak demand by charging a higher energy cost during those periods and lower costs during periods of low demand on the utility.”

El Paso is also commissioning an Economic Water Dispatch System to control all booster stations and pumps, so that when electrical costs are highest, the system will automatically select the most efficient pumps. It will also rotate all pumps to ensure that they are exercised. Operators and superintendents will receive information to help them monitor the wells and pumps. That program, when fully implemented in December 2013, has potential to save $300,000 annually.

Until then, plant operators continue implementing demand reductions manually. The policy requires them to use the most efficient pumps first, especially during peak periods. They must fill tanks and reservoirs and schedule all non-critical process activities during off-peak times.

For the operators, the energy policy has been fairly simple to implement. “Previously, their only goal was to produce good-quality water that met or exceeded state requirements,” Perez says. “After we adopted the energy policy, we explained to all personnel that energy was a very important component to the whole equation, so now they are much more sensitive to it. In the case of a water plant, they realize that instead of backwashing for two hours, they can monitor the system more closely and put the filters back into service when they are clean enough.”

Where natural gas-driven and electric-driven pumps are available, operators compare the real-time cost of using each option before choosing. “State regulations require the capability to switch to an alternate energy source, such as natural gas,” says Perez. “We can switch from electric to gas-powered booster pumps when the cost of electricity goes up.”

Looking deeper

Seemingly small changes are making a difference, too. In EPWU’s 200 control buildings where electrical control and communication equipment are housed for the wells and booster stations, seasonal adjustments to the thermostats are saving significant electricity. Perez noticed that the rooms were set to typical office temperatures, but studies showed that electronic equipment could operate unharmed in temperatures up to 95 degrees F. By changing the settings from 72 degrees year-round to 85 degrees in the summer and 62 degrees in winter, the utility will save 900,000 kWh per year.

Looking to save even more, EPWU will consider renewable energy sources, such as solar and wind power, and will use public education programs to help reduce water demand. Christina Montoya, vice president of communications and marketing, observes, “The utility’s reclaimed water and conservation programs that lower water use have delayed the need for water importation and expansion of facilities, while reducing chemical and power costs, saving the city an estimated $460 million since 1990.”


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