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Tuesday, Mar 19, 2024
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Infrastructure — Futuristic North County Water Plant Is Planned

ENCINITAS , The Olivenhain Municipal Water District has something in the pipeline that sounds like a pipe dream , tap water that is safer, cleaner and better-tasting than bottled water. All this from a futuristic plant that will cost less to build than a conventional facility.

The water district, which serves 49,000 residents in coastal North County, broke ground June 1 on a $30 million “ultrafiltration” plant. District officials said the plant, with a targeted completion date of 2001, would be the largest of its kind in the world.

San Diego-based Boyle Engineering will handle the construction, while Oakville, Ontario-based Zenon Environmental Systems will provide the ultrafiltration membranes that make the process work. Zenon will also operate the plant for a year, said Olivenhain spokeswoman Kimberly Robichaud.

Ultrafiltration purifies water by passing it through a membrane, which acts as a physical barrier to solids larger than the pores in the membrane. It separates the solids and even blocks harmful protozoa like giardia and cryptosporidium, according to a fact sheet from Zenon.

Air flow during the process creates turbulence, which cleans the membranes and also oxidizes iron and organic compounds, which removes additional impurities, the fact sheet stated.

An ultrafiltration plant has several advantages over conventional plants. Ultrafiltration does not require the harsh chemicals used in conventional treatment plants, while conventional plants cost more to build, Robichaud said.

Lower Construction Costs

Doug Gillingham, project manager for Boyle Engineering, estimated Olivenhain’s ultrafiltration plant will cost about $5 million less than a conventional plant with the same capacity.

An ultrafiltration plant also costs less to operate, Gillingham said. Ultrafiltration costs roughly between $210 and $285 for every million gallons of water treated, while conventional treatment costs between $300 and $375, Gillingham said.

Also, an ultrafiltration plant can be built in stages. The plant’s capacity can be expanded a little at a time, simply by adding more filters, while a conventional plant would have to be rebuilt to expand capacity, Robichaud said.

Another advantage over conventional technology is that ultrafiltration uses 75 percent less land, since it doesn’t require holding tanks. That further reduces capital costs, Robichaud said.

In fact, the entire Olivenhain plant will be enclosed. Since the new 25,000-square-foot facility is being built in the 750-acre Elfin Forest Recreational Preserve, the building complex will have a low profile, looking from the outside like a Spanish-style ranch and stables.

Ultimate Costs

The cost to build the ultrafiltration plant is $30 million for the first phase, which will be able to handle 25 million gallons of water a day. The ultimate cost will be $98 million for a plant capable of handling 82 million gallons a day, said Kimberly Thorner, project manager with Olivenhain.

The projected $98 million cost depends on future improvements in membrane technology. As the membrane technology has improved, the cost continues to decline, and Thorner is projecting similar improvements in the coming years, she said.

This $98 million price tag does not include the added costs of constructing pipes to convey the water from the plant to the current network. Another $15 million is the estimated cost to install pipes capable of handling the future use of 82 million gallons a day, Thorner said.

The cost also does not include additional filtration to remove total dissolved solids, such as salts and minerals leading to “hardness” in the water , something ultrafiltration cannot handle. This capacity may be added in the future through nanofiltration or reverse osmosis. But it could be very expensive, and the district does not have a timeline or a projected cost, Thorner said.

EPA Grant

Olivenhain already has a $4 million grant from the Environmental Protection Agency to pursue ultrafiltration. Whether the district adds nanofiltration capacity will depend on the district getting additional federal grants to make it feasible, Thorner said.

The water treatment plant is part of a larger system, which the water district is building in partnership with the San Diego County Water Authority. The Olivenhain project will build a 308-foot high dam and 24,000-acre-foot reservoir for emergency water storage and flow control. The dam will be built by December 2003, Thorner said.

Olivenhain’s water district covers 48 square miles and serves residents of Cardiff, Fairbanks Ranch, 4S Ranch, La Costa, Leucadia, Olivenhain, Rancho Santa Fe, as well as portions of Carlsbad, Encinitas, San Diego, San Marcos and Solana Beach.

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