LAKEPORT, Calif. —
Other development on similar soil in the county is stable, county officials said.
While some of the subdivision movement is occurring on shallow fill, De Leon said a geologist has warned that the ground could be compromised down to bedrock 25 feet below and that cracks recently appeared in roads well beyond the fill.
“Considering this is a low rainfall year and the fact it’s letting go now after all of these years, and the magnitude that it’s letting go, well it’s pretty monumental,” De Leon said.
County officials have inspected the original plans for the project and say it was developed by a reputable engineering firm then signed off on by the public works director at the time.
“I can only presume that they were checked prior to approval,” De Leon said.
The sinkage has prompted county crews to redirect the subdivision’s sewage 300 feet through an overland pipe as manholes in the 10-acre development collapsed.
Consultant Tom Ruppenthal found two small leaks in the county water system that he said weren’t big enough to account for the amount of water that is flowing along infrastructure pipes and underground fissures, but they could be contributing to another source.
“It’s very common for groundwater to shift its course,” said Ruppenthal of Utility Services Associates in Seattle. “I think the groundwater has shifted.”
If the county can’t get the water and sewer service stabilized, De Leon said all 30 houses in the subdivision will have to be abandoned.
The owners of six damaged homes said they need help from the government.
The Lake County Board of Supervisors asked Gov. Jerry Brown to declare an emergency so funding might be available to stabilize utilities and determine the cause of the collapse. On May 6, state Sen. Noreen Evans, D-Santa Rosa, wrote a letter of support asking Brown for immediate action. The California Emergency Management Agency said Brown was still assessing the situation.