Trace Levels of Toxins in North County Soil Are Found

A new study has discovered pockets of soil contaminated with trace amounts of toxic chemicals in northern Orange County, but state and local health officials say there is no immediate threat to public drinking supplies.

The toxic chemicals were found in shallow soil samples gathered during a yearlong study conducted by the Orange County Water District. The geologic survey was initiated to determine the extent of soil contamination--and its potential threat to ground-water supplies in a five-city area, including parts of Anaheim, Fullerton, Orange, Placentia and Yorba Linda.

Preliminary results revealed a number of toxic “hot spots” in the soil, particularly in north Anaheim near the water district’s ground-water recharge basins, where Santa Ana River water and storm runoff is captured and allowed to percolate underground. There also are about 100 domestic wells in the area, some within half a mile of the toxic “hot spots,” officials said.

As part of the study, district engineers drilled 425 holes in the soil at depths of six to 10 inches to test for chemical vapors and found varying amounts of tricholorethylene, or TCE, and perchloroethylene, or PCE.

TCE is a powerful cleaning solvent that was used by a number of industries, including dry cleaners, metal-plating firms and aerospace manufacturers until the late 1970s. PCE is still a commonly used cleaning agent. Both are suspected carcinogens.

A state ground-water expert said it is too early to draw any conclusions on whether the tainted soil may lead to a serious ground-water problem.

“What we have are a lot of questions, and that is a concern,” said Robert Holub, chief of ground-water investigations for the Santa Ana Regional Water Quality Control Board, a state agency that oversees water quality in Orange, Riverside and San Bernardino counties. “We don’t know if this is the beginning of a major problem or if this is the worst. . . . One thing we do (know), nobody is drinking unsafe water, as far as we know.”

To monitor the movement of the toxins in the soil, Holub said the water district plans to drill about 19 test wells in the area with the highest concentrations of contaminants.

“We will be watching the situation very closely,” Holub said.

The water district is responsible for managing the county’s vast underground supply of water, which is estimated to be as large as 35 million to 40 million acre-feet, and valued at several billion dollars. That is enough water to serve Orange County’s population well into the next century.

Most of the contaminated soil found in the testing was in the area of Orangethorpe Avenue and State College Boulevard, near State College and Katella Avenue, and in an area north of Riverside Freeway between State College and Tustin Street.

Holub said the source of the toxins in the soil is unknown, although both chemicals, which were widely used by industry, have been found throughout Southern California.

In the past year, three domestic wells in Placentia, Anaheim and Orange were closed because the water contained unsafe levels of TCE or PCE, water district spokesman Jim Van Haun said. But only trace amounts have been found in several dozen other wells, and Van Haun said, adding, “There is no immediate health threat to any public drinking supply.”