County Agrees to Test Hawthorne Landfill for Health Hazards : Pollution: The state says the plan is not enough to determine what is buried there. A system to pipe noxious fumes away, which homeowners have protested, is also planned.

County officials have agreed to conduct tests at the old Hawthorne Canyon landfill to determine if a long-term health hazard exists, but state authorities maintain that more should be done to find out if the dump contains potentially toxic substances.

Covered over decades ago, the dump lies under the back yards of 10 homes on Moccasin Lane, a residential street just off Hawthorne Boulevard in Rolling Hills Estates. In the 1980s, the yards began to crack and sink as dump wastes decomposed, leading to the escape of noxious gases and traces of cancer-causing chemicals, reports show.

The state Department of Toxic Substance Control had ordered the County Sanitation Districts of Los Angeles County to find out what kind of wastes were dumped and sealed in the six-acre canyon site in 1968 and to determine if there are any long-term health hazards.

No immediate health hazards were detected in a preliminary sampling of the noxious gases, county officials said.

After weeks of negotiations, the county has agreed to conduct tests “to determine whether human health may be threatened by the gases.� Sanitation districts experts are also designing a gas recovery system to capture the noxious vapors and pipe them away. Although they have agreed to do this much, they have balked at full compliance with state orders.

The state wants the county to bore dozens of test holes to determine what kinds of toxic materials are in the dump. Sanitation districts officials have refused, saying there is no need to spend money on such tests because only municipal wastes were dumped in the canyon.

State toxic experts, however, argue that the descriptions of municipal wastes a quarter of a century ago were so broad that deadly toxic materials such as benzene and vinyl chloride could have been legally dumped in the site. In addition, toxic substances from the adjacent and much larger Palos Verdes Landfill may be seeping into the Hawthorne Canyon dump site, state experts said.

County experts disagree and maintain that the Hawthorne dump is a separate landfill that was used and capped under legal agreements from the city and the private landowners. The property was later subdivided and sold.

In an Aug. 10 letter to state officials, the county said the planned gas recovery system and risk assessment testing are all that are needed to solve the problem.

Sanitation officials are drafting a final design for the underground recovery system, in which large collector pipes would be buried in trenches under the yards. The county would haul in clean fill dirt to “allow proper contouring of the areas affected by settlement,� the letter said.

“The sanitation districts have offered to install, operate and maintain this gas collection system,� said John H. Gulledge, a districts spokesman. The homeowners would have to maintain the earthen cap over the system, he said.

“The only thing preventing this work is the continued refusal of the property owners to grant their permission,� he said.

The property owners have made it clear that they do not want a gas recovery system in their back yards and instead are demanding that the sanitation districts or the city dig up the dump, get rid of the decomposing wastes and refill the canyon with clean dirt.

The homeowners filed claims totaling $56 million against the city and the county, contending that when they bought their homes, they were not told the canyon had been filled with garbage of any kind. Their claims were rejected, and lawyers for the property owners have threatened to file suit.

State toxic control experts said they welcome the county’s efforts to test the gas emissions and assess the health risks, and call the offer to build an underground gas collection system a step in the right direction. However, even if the property owners agree to such a system, it is not enough to satisfy the state agency, a spokesman said.

“It appears that the sanitation districts have taken the first steps toward reaching an agreement with us, but they still have a mile to go,� state toxics control spokesman Richard Varenchik said.

The state agency is insisting that the sanitation districts find out exactly what is in the dump, and Varenchik said the only way do that is to drill dozens of holes and test what is there.

If the county does not do the sampling, the state has the authority to do the coring and bill the county, at triple cost, he said.

“If they don’t, we can and if we do, it’ll cost them three times as much. We’ve got that authority,� Varenchik said.

Hawthorne Landfill A 23-year-old former dump fills part of a small canyon that runs across the rear of a dozen lots on Moccasin Lane, just off of Hawthorne Boulevard in Rolling Hills Estates. The earthen cap on the landfill has sunk six feet in some places, destroying barns and corrals and releasing noxious steam and methane gas.