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Michael Daly

wrote:

My questions are how does this plan sound overall, is there anything
you would do differently or add? Should I add any sort of landscape
cloth behind the rocks or plastic to keep the water from seeping out or
would that create too much pressure? On a wall of this height should I
place any rocks perpendicular that would sit back to the ground
formation and backfill over them? I guess this should add more strength
to the wall..

What you need to do depends on the slope and the type of soil. It can also
depend on the water table depth and rainfall.

If you build a retaining wall to hold up flat-topped soil, you are only holding
up the soil closest to the wall. If the surface is sloped enough, however, you
are holding up a potentially big chunk of the hill.

If the soil is prone to loosen up a lot when wet, then it could come down. At
one extreme, soils can liquify in an earth tremor and your wall has to be a dam.
I doubt you have that situation, but you have to consider that.

Removing the toe of a slope can cause the water to drain and wash out the base
behind your wall. This is especially true if the water table is usually high.
Another worst case scenario, but a vertical filter fabric can avoid some of that.

Buttressing the wall into the hill is always a good idea IMNSHO. That or some
kind of crib arrangement makes for a more solid wall. It can be cheap insurance.

A phone call to a local foundations engineer could tell you if there are problem
soils in your area. If not, you plan seems relatively sound. If the hill is
quite steep, though, you might want a pro to look at it.

Mike