Active Slide Hampers Access to SLVWD Lyon Surface Water Treatment Plant
By Julie Horner
It started about three weeks ago as a 6-inch crack. An employee noticed and said, “There’s a crack forming over there…better put some cold-patch on it.” The Lyon Surface Water Treatment Plant and its 3-million gallon welded steel holding tank, located at the top of a narrow, gated SLVWD access road about a mile from downtown Boulder Creek, tests and treats approximately 95% of San Lorenzo Valley’s drinking water. With this season’s unrelenting rains, the crack in the road quickly became a major break, sloughing and subsiding in terraced chunks at a rate of approximately six to twelve inches per day, ripping apart the asphalt to expose stepped strata punctuated by rivulets of runoff – effectively rendering the road inaccessible by motor vehicle.
A week ago the ground was still moving, creating an area that spans a dramatic 200 feet in height by 200 feet wide in what Director of Operations, Rick Rogers, said was called an active-layer detachment failure. And, he said, the series of underdrains and culverts that crisscross the mountainside “are not running water and we want to know why.”
According to an SLVWD press release, “The slide is not threatening the treatment plant or the steel water storage tank located at the site, and it is not having a direct impact on District operations.” Rogers said that employees have been forced to hand-carry 55-gallon drums of chlorine and other equipment to the facility, carefully skirting the slide.
From the treatment facility building at the top of the site overlooking the holding tank, support facilities below, and the forested vista beyond, SLVWD Environmental Manager Jen Michelsen said, “This is always where the water was stored,” referring to the original in-ground reservoir that served the valley long before the high-tech steel tank was built. She noted that the tank currently has a full stock of water in it, explaining how surface water from five area creeks (Clear Creek, Foreman Creek, Peavine Creek, Silver Creek, and Sweetwater Creek) are diverted in pipelines across Ben Lomond Mountain to the filtration plant and holding tank. Once the water is treated, it is gravity fed to neighborhoods primarily in the north system of SLVWD’s service area. Occasionally, the Lyon facility serves the entire District.
District staff and geotechnical engineers and geologists are working to determine a resolution to the failed access road, the moving landscape, and to ensure the safety and protection of downstream areas. No homes are threatened by the slide, though several trees in the area of the slide will have to be removed before they are taken down with the slide. The San Lorenzo Valley District Board of Directors held a special meeting on February 24 and voted unanimously to authorize $150,000 in emergency funds to attempt to halt the slide. According to the press release, “The District will seek to recover some repair costs through the County’s State of Emergency Declaration. This storm-related damage adds to the estimated $1.5 million in repair costs to the SLVWD water system this winter.” A request for federal funds was submitted to U.S. Representative Anna Eshoo’s office earlier this month. “We’ll be in a world of hurt if we don’t get FEMA assistance,” Director of Operations Rogers said.
Brian Lee, SLVWD District Manager, sent a recent update: “With the spate of sunny weather this week it appears that the slide has started to dry out a little and the sinking has slowed down. The District is now working to establish a temporary ramp that will allow delivery of chemicals and equipment by ATV. Our geologists and geotechnical engineers are working on additional temporary measures to secure the sight through the Spring. We will be developing a long-term fix soon after.”
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Julie Horner is Co-Founder and Editor for the San Lorenzo Valley Post. Julie lives and works in Boulder Creek and is an active participant in the county's vibrant music scene. She loves the outdoors and is the go-to expert on Santa Cruz Mountains hiking trails.
