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California Utility Overcomes Perchlorate Challenges
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Site of well F23, in Fontana, California, under construction
Workers construct a booster station at the site of well F23A, in Fontana, California. The two 500,000 gal reservoirs, to the right, enable the utility to pump water at night, reducing electricity costs. The massive ion exchange vessels are part of a lead-lag water treatment system. Courtesy of Fontana Water Company

The Fontana Water Company recently completed a new treatment facility that will bring an important well back into service following a spike in perchlorate levels.

October 1, 2013—The Fontana Water Company (FWC), in Southern California, recently completed a treatment plant, reservoirs, and pumping station at Well F23A, and are awaiting final approval from the California Department of Public Health to bring the high-producing well back online. The 2,300 gpm well has been out of service since 2009 when perchlorate levels spiked suddenly.

Perchlorates are of concern in the area, where synthetic perchlorates are used extensively in the production of rocket propellants and fireworks. In fact, the region has been the site of several U.S. Department of Defense (DOD) facilities as well as a fireworks factory. The salts can also be left behind by sodium nitrate fertilizer produced from Chilean caliche.

The FWC has lost 13 wells since 1991 to high perchlorate levels, and is closely monitoring other wells in which levels of the contaminant are rising. The private water utility has lost a total of 32 mgd of production capacity. In peak summer months, demand from the 209,000 residents in the service area is approximately 60 mgd.

“The lost well capacity has depleted our system redundancy,” says Josh Swift, the assistant general manager of FWC. He says the utility has bolstered supplies with untreated surface water purchased from the Metropolitan Water District of Southern California. But clearly a better solution was needed.

The new facility employs two pairs of Calgon Model 10 ion exchange vessels in a lead-lag arrangement. Prefilters remove any potential sediment from the well that could clog the resin in the vessels. Two 500,000 gal welded-steel, epoxy-coated reservoirs were added to the 1-acre site as part of the project. A new 7,250 gpm capacity booster station enables distribution to customers at higher elevations.

“The company’s business plan is to utilize the best available technology and treat any contaminant to the lowest detectable levels,” Swift says. “In the case of this facility, we have treated to ‘nondetect.’ Lead-lag is the best available technology for ion exchange and perchlorate removal. It gives us an extra sense of security. We monitor at the crossover, so once we receive a detection we initiate changeout of the lead vessel, and know we have an entire [additional] vessel to continue treatment. It’s a huge safety feature.”

The site was overexcavated by 10 ft for proper soil compaction for the reservoirs, which are founded on concrete rings with asphalt centers. The reservoirs incorporate flex couplings on all inlet and outlet pipes to avoid potential damage in the event of seismic activity. The reservoirs enable the utility to pump water at night, when electricity rates are less expensive, reducing costs. They also increase water supplies to meet fire demand flows.

The project was aided by $1.5 million from the U.S. Department of Defense (DOD) through its Environmental Security Technology Certification Program. The DOD provided some design support, the four exchange vessels, and half of the initial resin for the vessels.

The FWC will be grateful to welcome the well back into service and the approximately 3.5 mgd it will provide to the system, Swift says. Before perchlorate levels spiked, F23A was the highest producing well in the system. “Some of the other wells we’ve lost were old. We have wells that were drilled back in the 1920s. To lose an 800 gpm well, that’s one thing. But when you lose a 2,500 gpm well, that’s a whole different story,” Swift says.

When perchlorate levels in a well reach 50 percent of the maximum contaminant levels, the utility begins to develop a treatment solution. The utility is designing two more groundwater treatment facilities now. But a treatment facility is not always the appropriate option.

“One of the wells that has increasing perchlorate numbers now was drilled in the 1950s,” Swift says. “To put treatment on such an old well really doesn’t make sense. So we have pieces of land that we could fit a new well on. Just by chance, nearby water quality results indicate that we can avoid perchlorate [there] as well.”


 

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