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Water reclamation soars in sunbelt

By J. T. Long

In Las Vegas, one of the fastest-growing regions in the nation, a recent water resource plan estimated that the population of 1.8 million could grow to 3.2 million by 2025 with a need for 400,000 additional acre-ft/year Kay Brothers, deputy general manager, Southern Nevada Water Authority (SNWA) based in Las Vegas says, "Efficient use of water is a major emphasis throughout the west as populations grow and stress resources."

Reuse is a priority because the 300,000-acre-ft/year of rights to Colorado River water via Lake Mead to supply the seven water agencies represented by SNWA are on a "net" basis. Any water treated and returned to the river does not count against the agencies' allocation.

"We are also constantly having to meet stricter Environmental Protection Agency maximum contaminant levels and that requires investments in new systems," says Brothers. She points to a $12.25-million investment in ozonation equipment alone at the River Mountains and Alfred Merritt Smith treatment facilities. This represents one of North America's largest ozone operations. Lake Mead also houses one of the country's largest on-site sodium hypochlorite generation facilities and 83-ft-tall surge tanks (North America's tallest pre-stressed tanks when constructed in 2002) and the world's largest underwater concrete pressure pipe (12-ft diameter).

Las Vegas, Nev.-based MMC Inc. is currently leading a $46.5-million expansion of the River Mountains facility to bring capacity to 300 million gallons per day by end of 2005. Capacity could ultimately reach 600 mgd.

SNWA started an aggressive conservation campaign in 1991. Today, no grass is allowed on new businesses or in the front yards of new homes.

Potential new sources include a 1989 application for rights to 125,000 acre-ft/year of unused groundwater in east-central Nevada that is still in the EIS process for rights of way to transport the water over federal land. If rights are granted on schedule, SNWA would begin building production wells, 420 miles of pipelines and pump stations as early as 2015 at a capital cost of $1.95 billion.

An Arizona water bank could store 68,000-acre-ft/year of water rights. Another potential source, 180,000-acre-ft/year of water rights from the Virgin and Muddy rivers would require new diversion dams, 50 miles of pipelines, pump stations and treatment facilities to capture the resource before it conjoins the Colorado.

An even more political solution is a plan to pay for a desalination facility in California in exchange for Colorado River rights. "We determined that this is not an option for the next few years and are looking elsewhere for now," says Brothers.

"The most challenging thing for water agencies is getting permits," says Brothers. She budgets as much as 10% of project contingencies for studies, consultants and mitigation measures.

Quality Reclamation
In Texas, as in Nevada, the purple pipes of conservation and reclamation take center stage. "We have been using reclaimed water as irrigation since 1963," says David Ornelas, environmental compliance manager at El Paso Water Utilities.
Ornelas estimates that the 700,000 current users of 92,000-acre-ft/year will grow to 1.165 million people needing 228,330-acre-ft/year of potable water and 23,109-acre-ft/year of reclaimed water by 2060. The agency can't meet that demand with the 60,000-acre-ft/year rights to the Rio Grande and groundwater pumping from two aquifers. EPWU has invested $35 million in reclaimed water distribution lines, tanks, booster stations and sand filters at wastewater plants. As much as $32 million is projected to be spent over the next decade. One facility, the Fred Hervey plant, cleans water to potable standards for injection into the aquifer.

Denver, Colo.-based Western Summit broke ground in August on an $87-million reverse osmosis desalination plant to treat brackish water. The El Paso/Fort Bliss desalination facility will produce 27.5 million GPD of potable water, making it the world's largest inland desalination plant. Western Summit is also working on a $65 million arsenic removal system that will be completed in Jan. 2006.
Second Wave

In California, where the state water plan forecasts shortages of 2.4 million acre-feet per year minimum by 2020, water agencies are increasingly revisiting a system that went out of favor in the '90s because of high operating costs compared to post-drought surface water-seawater desalination.

San Diego County Water Authority (SDCWA) officials are considering two facilities, one in Carlsbad and one in San Onofre, north of Oceanside. The Encina Power Plant site in Carlsbad, which is currently in the enivornmental review stage, would be a public-private partnership with Poseidon Resources Inc. The Stamford, Conn.-based firm owns the rights to the site and plans a 50-mgd plant.

An $825,000, 18-month study by Irvine, Calif.-based RBF Consulting Inc. will determine whether Southern California Edison's shuttered San Onofre nuclear power plant's 12-in. pipelines designed to bring in seawater to cool the generating plant are in good enough shape to use for a 50-million to 100- mgd desalination plant. Two power plants are still in operation on the site.

"Continuing advances in reverse osmosis technology have brought the cost of seawater desalination down dramatically," says Bernie Rhinerson, SDCWA chair at a 2004 desalination workshop. He lauds the cost savings achieved by constructing a seawater desalination plant next to an existing coastal power plant and calls the "drought-proof" technology "a preferred supply alternative" that could provide the agency as much as 140,000-acre ft/year by 2020, 15% of forecast production. "Today, seawater desalination is cost competitive with other new water supply options available to the region," he concludes.

Metropolitan Water District (MWD) of Southern California charges between $30-acre-ft and $300-acre-ft depending rights, the source and treatment level. In Nevada, SNWA charges municipal water agencies $252 per acre-ft. According to the San Francisco-based California Coastal Commission, which must approve any desalination facilities, Most seawater desalination plants in California would produce water at a cost of $1,000 to $2,200 per acre-ft with a recovery rate of between 15 and 50 gallons of fresh water for every 100 gallons of seawater. Jason Allen, desalination engineer at American Water Works Association, predicts those costs will go down in the next six months as experimental facilities in Long Beach and elsewhere document improved technology and operations. "Operations are a huge issue because there are fewer steps and less forgiveness in membrane systems so they have to be treated differently."

The soonest Carlsbad could be built is 2011 followed by San Onofre in 2020 according to John Liarakos, SDCWA media relations officer.

Desalination is only one of the methods SDCWA is approaching as it attempts to diversify its water supply. The agency is currently working with the Coachella Valley Water District, Imperial Irrigation District and the state of California to line the All-American and Coachella earthen canal to save 93,900-acre-ft/year, of which the agency will receive the rights to 77,700-acre-ft/year. "The lining will conserve water lost due to seepage and help California reduce its overdependence on Colorado River Water," says Liarakos in a press release. Construction on 65 miles of parallel concrete canals began in Nov. 2004 and the final phase should be completed in 2008.

Florida was one of the leaders in desalination. Although Tampa Bay Water's $150-million, 25-mgd, reverse osmosis desalination facility is three years late, the St. Johns River Water Management District (SJRWMD) is looking at all options for meeting a projected 30 % increase in demand over 1995's 1,363.65 mgd. SJRWMD is working with local water agencies to undergo permitting and planning for a number of possible desalination sites in northeast Florida, according to Malissa Dillon, regional communication coordinator for the district. Two sites being considered on the Indian River are both near power plants. The Cape Canaveral Power Plant site would cost $215 million to build a maximum 45 mgd facility. A co-location with Reliant Power Plant would be $213 million for the same size treatment facility.

While some innovative water treatment solutions rival the costs of refined gas, the liquid gold can't take the place of tap water for the wave of new residents water agencies are trying to accommodate. Agencies are planning ahead and using improved technology to squeeze every drop they can out of every source at their disposal.