O.C. May Use Sewage as Barrier to Seawater : Conservation: Officials propose to use only treated waste water--instead of a mixture of it and deep-well water--as an underground barrier to seawater.

Orange County water officials want to inject millions of gallons of undiluted but highly treated sewage into the ground every day to conserve water and stem the tide of seawater migrating from the ocean.

State water-quality officials commend the Orange County Water District’s proposal as a good way to turn waste into a resource. But health officials are trying to determine if the waste water might pose a risk to public health if it flows into underground drinking-water supplies.

For 15 years, the water district has pumped a blend of one-third deep-well water and two-thirds treated waste water underground as a barrier to seawater flowing into the county’s valuable ground-water basin, which serves 2 million people. Now it proposes to use only treated waste water, conserving water that could be used to supply Orange County residents in drought periods.

“After (treatment), the waste water is as clean, if not cleaner, than the imported water supply we’re drinking right now,” said James Van Haun, spokesman for the Orange County Water District.

Currently, up to 15 million gallons of the waste-and-water mix are injected daily into the ground via 23 wells along Ellis Avenue in Fountain Valley. The change to straight waste water would save about 5 million gallons of water a day, enough for 5,000 households per year.

By the year 2000, the amount of treated waste injected would double to 30 million gallons daily.

Before the switch can occur, the regional Santa Ana board of the California Regional Water Quality Control Board must approve it.

“From a water-quality perspective, we’re in favor of the project,” said Jerry Thibeault, executive officer of the regional board.

“It provides a good steady source of supply to stop seawater intrusion, and it doesn’t use water that can be used for domestic supply.”

But approval cannot be granted by the regional board unless the state health department determines that the straight waste water would have no adverse effects on drinking water. Officials from the two agencies held a joint public hearing last week, with a final decision expected in October.

“The big question is, if they change their approach, could it have an impact on public drinking supplies down the road?” said Kurt Berchtold, assistant executive officer of the regional water board.

The nearest municipal drinking well, in Huntington Beach, is about 1,700 feet from the nearest injection point, and it would take at least three years, probably longer, for the reclaimed waste water to flow there, water district officials said.

The water is purified at Water Factory 21, the district’s state-of-the-art treatment plant in Fountain Valley, considered the most sophisticated in the world. It uses five treatment processes to remove pollutants from waste water.

State officials said the waste water is so thoroughly treated that it meets drinking-water standards for toxic pollutants and bacteria.

But health officials worry that small amounts of carbon-based chemicals found in waste could slowly seep into the basin that supplies drinking water, said Frank Hamamura, an engineer in the Santa Ana district of the state Department of Health Services.

The chemicals, types of organic carbons, are poorly understood and in minute quantities, but they could pose a long-term health threat, he said.

“A decision has not been made yet. We’re dealing with some substances that we don’t have much information about yet, and we have to weigh it to see if this is really a health concern or not,” he said.

Hamamura said the treatment removes other contaminants in sewage, including bacteria and viruses.

Nineteen monitoring wells in the injection area are tested for contaminants. Also, the county’s drinking-water wells are tested regularly, with about 12,000 samples taken annually.

Van Haun said 15 years of tests on Water Factory 21’s reclaimed waste water have not detected viruses or bacteria. He added that if the project is approved, the district would start extra monitoring for more contaminants.

“Our sense is that we’ll obtain approval with a few stipulations,” he said.

The reason that water district officials want to stop blending the waste water with deep-well water is that they found a way to start using that water for drinking supplies.

Until now, the deep water had an unpalatable brown color, but now the water agency has come up with a way to remove the color and make it a usable supply. Every drop counts, they say, especially because the state is facing a 4-year drought.

“We want to preserve it now, because it will provide a very viable water source here in the near future,” Van Haun said.

Water officials said the seawater barrier project is extremely important. If saltwater got into the ground-water basin, it would render the underground drinking supply useless.

Orange County’s huge underground lake, which contains millions of gallons of water, is a rare, invaluable resource. It makes the county less vulnerable to drought than most of Southern California, which relies more heavily on expensive water imported from the drought-plagued Sierra Nevada.

Orange County’s state legislative delegation has supported the proposal to stop the blending.

In a letter to the water board, the 13 legislators commended the district for its exemplary record in water quality and said the change “will not result in a relaxation of existing water-quality standards” and will save water, “which is critically important during times of drought.”

The Orange County Water District is known internationally for its innovative, advanced ways of protecting ground water and tapping into it for drinking supplies.

“It is a first-class organization, and they’re doing a real good job of monitoring the ground-water basin. That gives us more confidence about this proposal,” Thibeault said.

Two-thirds of the water consumed in the northern half of Orange County comes from the ground-water basin. Underground water from Irvine south is not used for drinking supplies, mostly because it is too salty.