During the summer of 2010, a retaining wall failed in Harrison, Ohio at the Cedar Hill Apartments.  The resulting wall collapse crushed at least one car and will cost tens of thousands of dollars to repair.  The retaining wall contractor contacted us to review this project.

At this site, the retaining wall was not able to hold back the soil and water behind this wall.  When all the material is removed, it is clear that bedrock exists behind the wall – and bedrock does not put ANY load on the wall.  So, why would this wall fail?

 

Well, the bedrock at this location will transmit water.  Water seeps out of the bedrock.  The space between the back of the stone wall and the face of the bedrock (being covered up) must be filled with free-draining stone by the retaining wall contractor.  Also, the water collecting in that stone must have a place to permanently drain.  If you fill the space with clay, it will get soft, wet and heavy and cause the wall to fail.  If you fill it with stone, but don’t drain out the water, the wall will fail. This is another example of the failure recipe “Just Add Water”.

You can see more of this project’s photos here

(State PE Registration Map)

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