Homeowner/Private Projects

For more information about slope failures and slope restoration, please follow the informational links below.

What is a slope failure or landslide?

How to identify the signs of a slope failure?

What are the most common reasons for failed slopes?

How can I prevent a landslide on my property?

When does Hillside get involved?

What steps do I take to repair my slope?

 

WHAT IS A SLOPE FAILURE OR LANDSLIDE?

slope failure

(geology) The downward and outward movement of a mass of soil beneath a natural slope or other inclined surface; four types of slope failure are rock fall, rock flow, plane shear, and rotational shear

In other words, a slope failure is a phenomenon that a slope collapses abruptly due to weakened self-retainability of the earth under the influence of a rainfall, saturation or an earthquake.

 

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landslide

Sudden downward movement of a mass of soil from a cliff or steep slope

 

Landslides happen when a slope becomes unstable, usually because the base has been undercut or because materials within the mass have become overly saturated with moisture.

 

 

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HOW TO IDENTIFY THE SIGNS OF A SLOPE FAILURE?

The first sign of trouble – A tension crack

There are occasions when a landslide or slope failure gives no warning or sign of an impending catastrophe.  Many times a failed slope does not ‘just happen’ overnight, but a tension crack will develop in the slope.  A tension crack is a void or fissure that normally runs parallel to the slope face.  They can be 20 feet to hundreds of feet long and can have gaps of ‘normal’ looking slope surface in between.  What is happening is a slide plane is developing below the surface, and the tension crack is usually the first sign of a failure.  Below are some other signs to look for:

1.      Is the slope eroding and sloughing off in large chunks because of the angle or height of the slope? This can affect structures nearby. Gravity will try to correct a slope angles greater than 45 degrees. Look for fresh erosion in large sections.

2.      Look at any trees on the slope. Are they growing straight or are they leaning downhill? Leaning fences, walls or vegetation means there is soil movement.

3.      Look for water springs seeping out of the hillside...almost always a problem!

4.      Look for "steps" of soil down the slope. This is where chunks of earth have broken loose in the past and moved partially down the hillside and stopped.  This is a dead giveaway.  Usually tenskion cracks are visible and a ‘head-scarp’ is developing.

5.      Any movement of the slope will create havoc with any structures within the slide plane of the slope failure. The depth of the failure and accessibility will determine the method of stabilization and repair.

 

Slope stability/slope performance concerns most hillside property owners. Heavy winter rains resulting in saturated earth materials can cause slope failures, landslides, and settlement. If such an event occur, the Department of Building and Safety typically issues an "Order to Comply". This may require a repair, acceptable to the Grading Division, within a specified period of time. Gravity and the lack of friction will typically reduce the gradient of most slopes; therefore, a steeper slope is more prone to instability and failures. Recent erosion and/or tension cracks in the exposed soil, parallel to the contours, may be indicative of recent slope movement or may precede slope failure. Leaning trees and curved trunks indicating that the tree has tried to right itself during growth, may be indicative of a long-term soil movement process called "downhill creep."

 

What are the most common reasons for failed slopes?

In laymen’s terms there are really only 2 causes of a landslide.

1.       Too much water – When soil gets over-saturated it loses cohesion and becomes too heavy to support itself.  With the aid of gravity the soil will slide down the hillside, usually in a continuous somewhat cohesive soil mass, leaving a scarp that is clearly visible.

2.       A seismic event – When an earthquake occurs, unstable soil becomes an easy target for failure.

 

How can I prevent a landslide on my property?

There are many things a property owner can do to prevent a landslide.  Below are some common sense things you can do.

1)      Live in the valleys and plains with all the other people instead of on hills with nice views.

2)      If you do live on a hill make sure your foundation is carved into solid rock.

3)      Seriously though…. If you do have a steep slope make sure that standing water is not allowed to sit on top of (ponding) the slope.  Proper drainage over slopes is a vital prevention measure and is the most cost effective way to prevent slope damage.

4)      Many of our repairs are caused by broken water lines that are undetected.  In some cases this has gone on for months before the surrounding slopes begin to fail.  If you see an uncommon jump in your water usage, call a leak detector out to your property to determine the cause.

5)      Make sure large trees with shallow root systems are not planted on the slope.  A common mistake is to plant eucalyptus trees on slopes.  They will regularly topple over in gusty winds leaving a scarp and a place for water to gather, causing further damage.  Medium size trees with invasive root systems (pepper trees for example) are a better choice.

6)      Rodent infestation in some areas is unavoidable.  Squirrels, gophers and moles dig holes in slopes that weaken the soil.  Make every attempt to eradicate vermin from slopes.  In only a few years a slope that was once firmly compacted so that water is not allowed to deeply penetrate the surface can be severely damaged by burrowing rodents.

7)       Surface planting is also vital.  Avoid heavy ‘iceplant’ type plants in clayey soil.  Ice plant is usually easy to grow, takes little water and fills in rapidly.  However, it can be a very heavy plant for weak soils and aid in the cause of a landslide, due to the additional weight.  There are better choices for slope planting that should be considered.  Please consult a landscape professional regarding your concerns for proper slope planting.  See our slope planting page .

  

When does Hillside get involved?  (Right now, please call us at 760-451-8600)

You can get us involved at any stage in the process. 

Have you already obtained a geotechnical or civil engineer? Let us help you with the rest of it. 

Do you already have a permit and you’re ready to go.  Give us a call and we’ll provide a competitive quote for the construction.

Is your project stuck in limbo with unresponsive engineers or city personnel?  We can help.

You are not sure what steps to take? Please read the ‘what steps do I take’ section below

 

What steps do I take to repair my slope?

1) The first thing to do is Call Hillside Slope Restoration at 760-451-8600.  We can help you with the following items:

A) Determine if permits are required in your particular city or county for the repair.  Including what type of permit, SWPPP’s plans, required department approvals, etc.

B) Determine if there is cause for insurance company involvement.  We have been able to interface between multiple property owners, HOA’s, and insurance companies to reach quick settlements and obtain the necessary funds for the repairs

C) Contract with and hire a geotechnical firm that will perform a concise site specific geotechnical investigation of the causes and (working with Hillside) determine the most cost efficient repair plan.

D) Working with our civil engineer, Hillside will provide plans and details, as specified by the geotechnical report, to meet all city requirements and approvals.

E) Assist in obtaining all necessary permits and construction bonds.

F) Build the repair project for you using all of our own equipment and crews in a professional workman like manner.

Please call so we can help you get this process started (760-451-8600).