Mitigating risk from loose boulders

[aayjaber]

There are loose or almost dislodged rock boulders on the site above a property I am developing. The size of the boulders (assuming spherical shape by way of approximation) ranges from 2 to 4 ft in diameter. What action can be taken to mitigate the risk of the boulders rolling on my property? is building a retaining wall of 2 to 3 ft high good for deflecting rolling boulders?

 

[GabionGuy]

Look into rockfall drapery systems. Contact Maccaferri or geoBugg for information. If you are in North America, FHWA released a useful design manual on rockfall drapery about 2 years ago.

 

[msucog]

it seems to me that it would depend on the gradient involved. if possible, i my estimate it looks like it would be much easier to send a trackhoe mounted hoe-ram (or a half dozen guys with jack hammers) to go bust up the things.

 

[cvg]

are there any loose rocks at the base of the hill now? you can get a good idea if you will see any more rocks fall down by what has happened in the past.

 

[aayjaber]

The dislodged boulders are not on my property but rather on the property above mine. The area where the dislodged boulders sit sloped up from my property line, I estimated the sloping up from the top map to be around 25 ft for 70 ft that is around 35%. Some of the boulders are completely dislodged because they seem to have been worn out being very weathered so they split from the rock under which they used to be part of. There are other boulders that are not dislodged but rather are cropping out and still part of the rock base. I am now thinking my options are:
1- If the owner of the property above mine allows me to remove the loose boulders I will do so, I actually need the rock for building terraces, I have a feeling the owner is open to removing the rocks that he knows could become a potential liability for him.
2- If the removal of the loose boulders is not possible due to what ever reason, I would like to know if I can set up some sort of barrier on the property line to intercept any falling rock. I think a stem retaining wall of 3 to 4 ft strongly reinforced can withstand the impact of any falling rock. It is easy to model the kinetic energy from the falling boulder. My assumption if any rock falls if will roll like either a ball or a sphere depending if it it closer to being a sphere or a cylinder in shape after approximation. It is easy to set up the kinetic energy range for falling rocks depending on their mass and how high from the barrier, the design of the barrier will take into account the range of the kinetic energy the barrier will be impacted with.
3- The other option is to set up a barrier of steel posts and mesh, I saw some of that of the referred sites. This could play well because the barrier could act as a see through fence and falling rock barrier.

What else can be done?

 

[oldestguy]

I live in a area where this is a problem, mainly for highways below. At times, such as spring thaw, they come down. That is not the end of the things that have happened.

However, there have been occasions where heavy rainfall has caused slides and other erosional problems. So, what I am bringing up is are you prepared for more than just boulders, such as landslides, etc?. How about trees losing their support?