Dioxane tests recycled water plan

June Casagrande

A potential cancer-causing chemical found in drinking water

supplies earlier this year gave a startling lesson for a groundwater

replenishment system planned to take effect in 2007.

The chemical 1,4-dioxane got into water that had been through a

treatment that officials had believed would filter out all such

chemical agents. This treatment process, known as reverse osmosis, is

integral to the region’s plans for replenishing ground water.

“We learned a lot of lessons from this dioxane,” Mayor Tod

Ridgeway said. “Now we know that when we do the groundwater

replenishment, we now know there are a couple of substances that can

get through reverse osmosis.”

The groundwater replenishment plan, also known as “toilet to tap,”

will channel wastewater from the Orange County Sanitation District

through a number of treatment processes, ultimately sending it to

huge basins in Anaheim where it will seep through the Earth and

settle back into the region’s underground aquifer.

Now, thanks in part to the dioxane discovery, officials know of at

least a handful of contaminants that can stay in the water throughout

these processes.

In addition to the dioxane, which was cleared from local water

supplies about four days after it was discovered in February, at

least three other substances have been labeled “chemicals of

concern”: a jet-fuel byproduct called perchlorate; an industrial

chemical known as NMDA; and the fuel additive MTBE, which,

ironically, was put into fuel to reduce the environmental hazard of

air pollution.

In hopes of ensuring water safety in the ground water

replenishment plan, City Council members will consider sending a

letter to state drinking water regulators asking them to help set and

oversee drinking water standards.

“Up and down the state, people are going to have to look into the

question: To what level of treatment should this waste water be

treated to?” said Assistant City Manager Dave Kiff, who was directed

by the city’s water committee to compose the letter to the state

Department of Health Services’ drinking water division.

City officials had to shut down wells for four days after the

1,4-dioxane discovery earlier this year and imported water from the

Metropolitan Water District in the meantime.

Health authorities have never set limits for how much 1,4-dioxane

is a health hazard. But local authorities say that the amounts found

in Newport Beach water supplies earlier this year were very low and

very likely to be safe.