SANTA CLARA – Several homes in Santa Clara are being torn down in preparation for work to stabilize a hillside that has been slipping for decades.
Two homes on Crestview Drive and one on Cinnamon Circle were purchased by the city in the past three months.
A second home on Cinnamon Circle has been owned by the city for a decade or more.
Two vacant lots have also been purchased; city workers are in the final stages of tearing down the houses.
The demolitions will make way for a project that is expected to stabilize the hill and prevent damage to more homes.
“We’re hoping,” Santa Clara Mayor Rick Rosenberg said. “No guarantees with a landslide, but we’re hoping. At least it’s going to increase the factor of safety for the remaining homes.”
The slide, located near Truman Drive on the southern edge of Santa Clara Heights, is believed to be caused by several factors, Rosenberg said.
“It’s a combination of the steep slope and the ground water that gets introduced into the soil, and then gravity does its work.”
Attempts to pinpoint the source of the water have been unsuccessful and repeated efforts have been made to stabilize the hillside. At least 26 homes have been impacted by the slide, Rosenberg said previously.
The stabilization effort will include grading the top of the hillside to remove weight from the top of the slide area, installing ground water drains and building an earthen buttress at the base of the slide.
Behind homes on Cinnamon Circle, the hillside has sloughed away and created a nearly vertical drop-off.
“We’re going to take that vertical scar that was there by the Hafen home, and flatten it out … and then use that material to build a buttress at the bottom,” Rosenberg said.
After the design work has been completed, the earthworks portion of the project will be put out for bid. Rosenberg hopes work will begin by the end of August or the first of September.
Five boreholes have already been drilled in the hillside as part of a geotechnical engineering study. The city council is expected to authorize funding for three more holes to help determine the best way to build the buttress at a regular council meeting Wednesday at 5 p.m.
“There are some sandstone layers in there that have a big impact on where you put that buttress for it to help stabilize the slide,” Rosenberg said. Sandstone layers are intermixed with mudstone and clay layers.
“The sandstone layers hold the water and provide a little bit of stability, but you’ve got to know where they’re at in order to actually design your drains and your buttress down at the bottom.”
The total cost of the project is estimated at $1,562,713, including the property purchase and hillside stabilization.
A FEMA grant will cover 75 percent of the cost. It is hoped that a $351,000 Community Impact Board loan and the city’s contribution of $20,000 in cash and another nearly $20,000 of in-kind contributions will cover the balance of the project.
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