Debris Fences

There are two different approaches to preventing debris from an upper un-stable slope from negatively
impacting property and/or safety below.  Both approaches start with a calculation of total potential energy -
which is basically a function of (a) mass of debris likely to break free (b) vertical distance through which
that mass can travel before being arrested.

The philosophy behind the first approach is to constrain the vertical distance through which a potential
break-away mass can accelerate as much as possible.  The solution is basically to put a large "net" over the
entire unstable slope..  On the north side of Laguna Canyon Road, pulling into town, one sees an example
of this.  If this is not feasible (due to access or due to property line locations or due to aesthetics, a second
approach is to build a barrier at the lower perimeter of the unstable slope.

The fence at the lower perimeter of the unstable slope is designed in such a way that there is a cascading
series of mechanical links, all designed to fail in a controlled way to absorb the potential energy from any
slope failure.    Plant material grows easily through the links to allow the fence to almost disappear visually
within a couple of years.