Slope creep, also known as downhill creep, is a common natural occurrence in drought-stricken California. It can destroy your home’s foundation and put your family’s safety at risk. The worst part is creep is slow and subtle making it difficult to recognize the signs. If you want to know what downhill creep is and why it’s so common in the Golden State, we explain the basics of this phenomenon below.
Slope creep is a gradual process where rocks and soil “creep” or slowly progress down a low-grade slope.
Slope creep is difficult to notice—generally, soil creeps at a rate of just 0.3 cm to a few centimeters per year. But over time, creeping soil can seriously damage your home’s foundation, as well as its framing and water lines.
Downhill creep doesn’t happen exclusively in California, but Californian properties are especially prone to it. There’s the issue of SoCal’s unfortunate topography, which consists of “cut and fill” residential lots. When moisture levels in the soil are too high or too dry, these lots are prone to downhill creep. Shrinkage of the soil due to a reduction of moisture causes separation of the base layer from the fill layer, causing the two surfaces to slip due to lack of friction.
Over the past 15 years, drought conditions have exacerbated the issue by causing the soil behind hillside retaining walls to dry and shrink away. This condition can increase the potential for slope creep, especially on fill lots. Properties built on steep slopes are more susceptible to cracking, and layer separation as the soil shrinks due to the reduction of moisture content.
Water or moisture is volume. Reducing the amount of moisture results in shrinkage, settlement, and in the case of hillside properties, downhill slip or creep. Unfortunately, this also provides an easy channel for winter rains to percolate behind retainer walls, foundations, and layers in the soil, occasionally causing the catastrophic failures we see every year.
Take this recent incident, for example. A landslide occurred in the early morning of December 9th at Palos Verdes Estates near Beach Club Road and Rosita Place. A cliff collapsed, sending mud, dirt, rocks, and debris tumbling to the ground below, some of it even striking a passing county maintenance truck. Fortunately, no one was injured in this incident. But there have been numerous cases where slope creep has decimated properties and taken lives.
Slope creep may be the slowest form of landslide, but its speed—or lack thereof—doesn’t make it less dangerous. And the last thing you want is to risk your property and personal safety by ignoring the signs.
Now that you understand the basics of downhill creep, you may wonder how to fix it. If you live on a hillside fill lot or have a retainer wall that’s beginning to lean at an unsafe angle, it may be time to consult a professional to determine if you need repairs.
Foundation Tech is a foundation repair company with years of experience dealing with California foundations. If you suspect your home is at risk of creep, give us a call or click “contact us” on our website to speak to a member of our team and learn more about our company and services.
We understand the causes and symptoms of slope creep. We can professionally and permanently repair leaning retainer walls and cracking foundations and stabilize them using caissons and helical tie-backs to prevent soil movement and keep creep at bay.