A group seeking to shut down Toland Road Landfill is asking state officials to investigate a geologist's report that indicates half the dump is built upon a massive landslide area.
Renewed movement of the 5,000-year-old slide, perhaps caused by an earthquake generated by nearby faults, could harm the landfill's structural integrity, according to a geologist hired by Ventura County Citizens to Stop Toland Road Landfill.
"The risks are obvious," said Gordon Kimball, a member of the group's steering committee. "Clearly, if this landslide moved, the landfill would be severely damaged, if not destroyed."
The group has submitted a 16-page report outlining its findings to the Regional Water Quality Control Board.
Officials with the state agency could not be reached for comment Monday.
A spokeswoman with the Ventura Regional Sanitation District, which operates the landfill, said the district is preparing a response to the report.
"Keep in mind this expert is the same expert that alleged there was an active earthquake fault running right through Toland," said Sue Smith. "He has since admitted that allegation was never proved."
Kimball said geologist Eldon Gath discovered evidence of the old landslide after hearing that the infamous failure of the St. Francis Dam in 1928 could be traced to instability of the old landslide it was built upon.
Gath reviewed aerial photos of the landfill and reached the conclusion that the landfill was built upon a landslide more than half a mile long and half a mile wide. Two other geologists who reviewed Gath's data agree with his conclusions, according to the report.
Nearby residents have long fought an unsuccessful battle to prevent the expansion of Toland Road Landfill, located midway between Fillmore and Santa Paula.
Previously a small regional dump for residents of the Santa Clara Valley, the dump has accepted most of west Ventura County's trash since Bailard Landfill near Oxnard closed in 1996.