Belmont residents keeping wary eye on hillside after weekend mudslide damages homes

BELMONT -- A portion of San Juan Boulevard in Belmont will be closed for at least another two weeks following a mudslide that caused officials to red-tag three homes. 

The mudslide came down Saturday during one of the many recent storms that battered the Bay Area. Homeowners who live near the mudslide say they are keeping a close eye on conditions as the rain finally gives them a break but the stability of the ground remains uncertain to city leaders and local experts. 

More time is needed to let the ground dry and assess how best to respond to this mudslide and others in the Bay Area.

"The power of water is amazing and seeing that slippage on that house up there is daunting," said Belmont resident Glenn Morgan. "You're still leery of any heavy rains because you never know, it's that unpredictable situation, I never would have thought that what happened up the street was going to have occurred there and then but it has."

Some of the homes on the same road have been left with the ground below their foundations exposed after the slide. Morgan has lived on that street for decades, making upgrades to his home and the property. One major change was the retaining walls he installed in the backyard. It's a way to try to mitigate any movement by the hill behind his house along with a creek he and others maintain to keep the water moving past them.

"Yeah, it came up to where you see over the top of the drain," he told KPIX while pointing to the low levels of the creek on Wednesday. "These posts are still holding after 25, 30 years."

Mud remains on the roadway and because it may be holding up the slide, city staff are reluctant to move it yet. The current plan will have them wait seven to ten days to get the right specialists and engineers out to survey the site, determining how best to stabilize the slide.

"They understand this is a really unusual, unique incident and we're just looking out for the safety of everybody," said Mayor Julia Mates. "We've been prepared to the best of our ability but it's hard to know in storms like this exactly what's going to happen and what's going to be the outcome."

At least three homes were red-tagged after the mudslide and while city leaders say they hope they can avoid giving that notification to other residents, it is too early for them to tell while the ground remains extremely saturated.

"When we see previous events in an area, it means that we know there is continued risk for movement in those areas," said Dr. Laura Sullivan-Green, the department chair and a professor of civil and environmental engineering at San Jose State University. "If you live downslope of any significant soil mass or rock mass that has had movement before, you always want to keep an eye on what's happening upslope."

Sullivan-Green says the majority of the activity we're seeing locally are mudslides with some landslides. The major difference being the amount of water and the depth of the movement. Mudslides tend to have more water and are shallower while landslides may have less water and could be deeper. The area of greatest concern to her at the moment is in the Santa Cruz Mountains where there are recent burn scars.

"We really need to see the rain stop and stop for more than a day or two before we can go in and make any major assessments for an area," she told KPIX. "If you can do anything to improve drainage on your property or the area around your property, that is the best thing we can do in short term, is give the water a place to go."

While they cannot make exact predictions for future activity, Sullivan-Green says there is research happening around the state to get better at that science. This recent activity stands out to her from other weather events though since she moved to the Bay Area 14 years ago, Sullivan-Green says one other factor that is concerning is the drought. The soil is so dry it cannot absorb water as easily.

Beyond the slides in this part of San Mateo County, residents are also looking up to the trees to see how they fair after recent storms.

"You just pray those winds aren't going to cause more problems," Morgan said. "Naturally when the water is present, it can be rather scary but so far it's doing fine."