EL TORO MARINE BASE : Ground-Water Test Results Awaited

Officials at El Toro Marine Corps Air Station are awaiting lab results that might determine what substances have contaminated the ground water under a large swath of the base.

Scientists are now analyzing water and soil samples collected from more than 100 monitoring wells, both on and off the base, which were installed over the last year, said Col. Ronald Lard, the base’s assistant chief of staff for environment and safety.

Once the substances are identified, officials plan to clean up the contamination, Lard said.

One of the substances in the ground is believed to be trichloroethylene, or TCE, a hazardous solvent used in degreasing aircraft engines.

TCE was one of several hazardous materials dumped at more than 22 sites around the 5,200-acre base, mostly before the late 1970s. Some of the materials are considered cancer-causing.

The base is on the nation’s Superfund list of the most dangerous toxic sites and is considered one of the worst dump sites in Orange County.

Officials hope to learn what portion of the base is tainted once water and soil samples from the wells are analyzed. Wells have been placed as far as 2 1/2 miles outside the base to see if any materials have spread to those areas.

Investigators have found no evidence that the substances have tainted drinking water supplies, which are located deeper underground than ground-water tables, Lard stressed.

Base officials plan to clean up the contamination by running the ground water through an Orange County Water District desalting plant. The process will remove all traces of TCE, Lard said.

“As the water is removed from the ground, the contaminants are removed from the water,” he said.

The water will then either be pumped back into the ground or used for drinking, he added.

As officials await the test results, which should be completed by May, crews are digging the last of the monitoring wells. Some wells go as deep as 200 feet.

The excess water collected during the well drilling is treated and then reused in irrigating the base’s golf course, according to base officials.

The complicated treatment includes running the water through granular-activated carbon.

As for excess soil samples collected, officials plan to place any contaminated materials in a special holding area before transporting them to a hazardous waste disposal facility off the base.

Base officials said none of the soil collected so far has been found to be contaminated.