Fireworks Ignite Water-Safety Fears : Antelope Valley: Officials worry that residue from eight tons of material blown up by firefighters may endanger the supply. A firm is hired to test the soil.

When firefighters blew up eight tons of fireworks as part of a pre-Fourth of July safety demonstration last month, they touched off an explosion of another kind.

Water officials in the Antelope Valley say chemical residues from the fireworks may have endangered the local water supply and have hired a private firm to take soil samples in the area.

Fire officials, after first saying the Palmdale Water District was overreacting, now have agreed to cooperate in the investigation.

“If they’re concerned, we’re concerned,” Deputy State Fire Marshal David Walizer said. On June 27, state and county fire officials exploded illegal fireworks that had been collected countywide in recent years. Walizer said there were firecrackers, skyrockets and other explosive devices. The spot chosen for the demonstration, to which the media were invited, was a 200-foot-deep gravel pit owned by Antelope Valley Aggregate Inc. on Avenue T.

Walizer said the Los Angeles County Fire Department picked the site because it appeared safe. He said fire officials had no idea that it was one of the two most important areas in the valley for replenishing ground water from streams in the San Gabriel Mountains.

Harold Fones, manager of the Palmdale Water District, said the district has for some time expressed concern about development in the area and its impact on the water table, which supplies the area with 50% of its water. The rest comes from the State Water Project.

Fones said he did not find out about the demonstration until he read accounts of it in the local newspaper. “We were quite surprised,” he said.

Fones fired off a letter to the Fire Department, asking to take soil samples at the site “to determine chemical residues that may become part of our water supply.” He said that since the fireworks may have come from other countries, they might contain heavy metals and other dangerous compounds.

“God knows what they’re made from,” he said.

Last week, Walizer said the district was overreacting, claiming that everything had burned up.

Later, however, other Fire Department officials said ashes were left from the explosion and these had been buried at the site.

Fones was surprised by the criticism. “Our letter was quite mild,” he said.

Walizer said a Pasadena firm has been hired to analyze soil samples taken from the area where the ashes were buried last Friday. If fireworks residues are found, they will be dug up and hauled away to a dump that accepts hazardous waste.

“We’re very sensitive about this now,” Walizer said.