Technical Problems Snag Spill Cleanup : Derailment: Delay in removing toxic chemical will keep U.S. 101 closed until at least this afternoon.

SEACLIFF â€”  A cleanup effort delayed for two days by technical snags and equipment problems got under way Tuesday afternoon at the site of a Southern Pacific freight train crash and toxic chemical spill that continued to keep a 10-mile stretch of U.S. 101 closed near Ventura.

The freeway was expected to remain closed until at least this afternoon. The delay in the cleanup also was keeping evacuated residents from returning to 49 nearby homes, officials said.

The cleanup of 440 spilled gallons of aqueous hydrazine--a jet fuel additive that is a suspected carcinogen--had been postponed for a variety of reasons, including concern about the possibility of explosion and a lack of proper equipment, the emergency officials said.

Dick Perry, Ventura County Fire Department assistant chief, acknowledged that the cleanup was running at least a day behind schedule, but said that there was no immediate environmental danger.

“It’s a stable site in terms of the material not spreading outside the immediate area,� Perry said.

By Tuesday afternoon, toxic-chemical handlers clad in white, airtight suits began vacuuming out 15 drums, each containing 55 gallons of hydrazine, that had been punctured in the crash. They also placed another 39 drums, which were damaged but not punctured, into larger vessels, sealed them and removed them from the ruptured 50-foot cargo container.

Hydrazine is a chemical that causes nausea, lung and eye irritation and even death in cases of prolonged exposure. The substance came by rail from Olin Chemical in Lake Charles, La., and was bound via Los Angeles to San Francisco for shipment overseas, said Mike Furtney, a spokesman for Southern Pacific. Furtney said he did not know the container’s final destination.

On Monday afternoon, the cleanup crews hired by Southern Pacific to apply a chemical meant to neutralize the spilled material’s toxic properties halted work after discovering there was a risk of triggering an explosion.

The neutralizing chemical the workers were planning to use is an 8% solution of swimming-pool chlorine that creates explosive hydrogen gas and small amounts of ammonia when mixed with hydrazine, Perry said.

Site supervisors for the cleanup contractor, OHM Corp. Environmental Services, determined that if they had sprayed the chlorine solution on the drums, the chemical reaction would have produced a cloud of hydrogen gas thick enough to risk a massive explosion, Perry added.

After deciding to postpone their first cleanup plan, officials ordered in a tank truck later Monday afternoon so workers could vacuum out the contents of the drums.

But OHM supervisor Herbie Bart called a halt to that plan when he learned that the tank was made of carbon steel, rather than the stainless steel he had ordered. The hydrazine could have eaten through the carbon steel, said Ventura County Fire Capt. Norm Plott.

The stainless steel tank arrived after 9 p.m. Monday. But when it was backed up to the wreck, OHM workers found its hose would not reach the drums, Plott said.

By the time the truck could be repositioned and workers suited up, it was 2 a.m. Tuesday and county emergency officials called a halt to the cleanup, Plott said.

“These people are in very, very bulky suits that limit their movement,� Perry said. “They get fatigued when they make entry after entry into the site, and it takes a toll on them.�

By late Tuesday, three people at the crash scene had been sickened by fumes, but none required hospitalization, officials said.

The neutralization of the hydrazine was expected to be finished Tuesday night, officials said. That would allow Caltrans bridge inspectors to examine a concrete pillar supporting the freeway overpass at the crash site to see if it was damaged by the derailment.

The southbound lanes are likely to be opened first once the cleanup is completed, and the northbound lanes will be opened as soon as possible after the support pillar is inspected, said Russell Snyder, a Caltrans spokesman.

The cleanup is costing Southern Pacific more than $50,000 per day, but the delay was unavoidable, said Jack Jenkins, a railroad spokesman.

Meanwhile, the Ventura County Board of Supervisors declared the crash site a local emergency.

The declaration allows the county to seek state and federal emergency funds, said Karen Guidi, program administrator for the county’s Office of Emergency Services.

Reed Smith, hazardous-materials officer for California Department of Fish and Game, said that the spill was not considered a threat to wildlife. “What we don’t know, however, is how far the hydrazine sank down into the ground. Hydrazine is extremely hazardous to aquatic organisms.�

Times staff writers Joanna M. Miller and Hugo Martin contributed to this story.