Sewer-water system begins filling aquifer

Purified wastewater is being sent to settling ponds in Anaheim

Pat Brennan
The Orange County Register
01/22/2008

A system that converts sewer water into drinking water has begun channeling its product into settling ponds in Anaheim, where it will sink into the county's deep aquifer, an important local source of drinking water.

On Friday, the Orange County Sanitation District began sending purified wastewater through a pipeline to the two Anaheim settling basins. Earlier this month, the Groundwater Replenishment System began piping water into an underground barrier that prevents seawater from seeping into the aquifer. But the agency had to wait for final state approval before sending water to the settling ponds.

Although state health officials required that the water receive an extra level of treatment – being filtered through sand and rock on its way down to the aquifer – experts say that last step is probably unnecessary.

The $480 million system uses high-powered, reverse osmosis filters to treat the water, which arrives from the Orange County Sanitation District, adjacent to the water district in Fountain Valley, after pre-treatment to remove contaminants.

The water is then exposed to hydrogen peroxide and ultraviolet light to destroy any remaining organic material.

It will produce up to 70 million gallons per day, half for the seawater intrusion barrier and half for the county's drinking-water supply. But most of the seawater-barrier water also eventually becomes part of the drinking-water supply, said Orange County Water District spokesman Ron Wildermuth.

When the Groundwater Replenishment System hits the 70 million gallons per day, which it is working up to, it will produce an estimated 10 percent of all the water used countywide.

The treated water will mingle with other water in the deep aquifer, and it will likely be six months to a year before any of it is pumped out and consumed, said Orange County Water District spokesman Ron Wildermuth.

Only north and central Orange County receive water from the aquifer; South County relies almost entirely on imported supplies.

Contact the writer: 714-796-7865 or pbrennan@ocregister.com.