|Ground movement has continued at the Lakeside Heights subdivision in north Lakeport, Calif., where water saturation – believed to be from an irrigation pipe – has led to potential landslide conditions. Photo by John Jensen.|
LAKEPORT, Calif. – A hillside that’s experienced ground movement leading to a potential landslide, with resulting damage to several homes, may be the result of a subdivision’s irrigation line, county officials said Thursday.
Lake County Special Districts released initial results of a leak detection report on Thursday for the Lakeside Heights subdivision, located off of Hill Road in the north Lakeport area.
The results so far suggest that a 2-inch irrigation line owned by the Lakeside Heights homeowner’s association could be the culprit, but further study is under way, Special Districts reported.
Late last month, the county red-tagged three structures and began to conduct an investigation after a deep fissure in the earth opened up and a large section of ground sank.
That ground movement damaged the homes and a sewer line, and endangered the Special Districts water line that supplies the subdivision as well as Hill Road, as Lake County News has reported.
Since then, the ground movement has continued, with a visit to the site on Thursday showing that the ground had sunk several more feet, with the structures of the homes showing more damage.
Special Districts, which monitors the area, reported that it immediately noted the leak last month and installed an emergency bypass until it could ensure that a permanent repair would not be damaged again by further movement of the hillside.
While inspecting the area where “significant movement” of the ground occurred, Special Districts staff noticed it was saturated with water, which is believed to be contributing to the unstable hillside.
Because the water could have been coming from a a leaking irrigation line, water line or a natural spring, Special Districts – in an effort to ensure it wasn’t public water lines causing the problem – hired a leak detection firm to test all lines within the public water system feeding Lakeside Heights subdivision.
The test was performed by Specialized Utility Services Program, a subsidiary of California Rural Water Association, using state-of-the-art equipment, including leak surveyors and correlators, pipe locators, hydrophones and computerized leak sound loggers, Special Districts reported.
The agency said the enhanced correlation function identifies narrow-band leak noise- making it ideal for PVC pipes, small leaks, multiple leak situations, and testing environments where there is high background noise.
Special Districts said all of the public water system lines that it maintains and which feed the subdivision were thoroughly surveyed through 10 incremental sections, working from one valve to the next.
The results of the leak detection test were received and reviewed by Special District’s staff. The agency’s Thursday report said there were no leaks detected in the district’s lines, but the report did note a suspicion of a significant leak or leaks in the homeowner’s association 2-inch irrigation line.
|A roughly 30-foot-wide area of ground has sunk several feet, damaging homes – causing cracks in some and pulling others from their foundations – and endangering a water line at the Lakeside Heights subdivision in north Lakeport, Calif. Photo by John Jensen.|
The Specialized Utility Services Program report said the “area of concern was at the 2 inch RP irrigation service off the main distribution. When the valve was turned on water was running out down the hillside. We validated that by shutting the RP valve, there was no leak on your system.”
“Although we hope the geotechnical report will provide us with answers as to the cause and expected magnitude of the hillside slippage, we feel that any excess water saturation can only make this situation worse,” Special Districts said in its Thursday report.
In the interest of public safety and to prevent further damage until the geotechnical report can determine the exact cause and magnitude of this issue, Special Districts said its staff is physically disconnecting the irrigation line until it can be inspected and repaired as needed.
The Board of Supervisors at its March 26 meeting approved Special Districts’ request to contract with a geotechnical engineer.
The agency said Thursday that it hired RGH Consultants to perform a geotechnical investigation, which was necessary because Special Districts determined it couldn’t implement a permanent repair a the site until it knew the cause and magnitude of the earth movement.
Special Districts said that its primary focus is on preventing further damage to the sewer lines and protecting the water lines, however, officials believe the report will be useful to property owners, other county departments and various entities involved with the Lakeside Heights Subdivision, and the results will be made available to anyone who can use them.
The geotechnical investigation is based on measuring movement of the hillside over a period of time so Special Districts does not expect the results of that report for three or four weeks.
The leak detection report is available and may be viewed during normal business hours at Special Districts’ office, located at 230 N. Main St., Lakeport.
Email Elizabeth Larson at firstname.lastname@example.org . Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.