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RE: Assistance With Retaining Wall, Wood vs. Block?

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Rick,

I echo my fellow engineers in saying, "hire and engineer."  You both can go
over many options and alternatives, life cycles, and what have you.

That being said, a wall this high will likely need to have some sort of tie
back, or dead man.  I might recommend using helical piers, as these are good
tools for tie backs, and take very little effort for installation for
several wall options.  Geogrid will also work well, but requires removal and
installation of material to achieve tie back requirements.

I wouldn't recommend you enter this project as a home owner trying to save a
buck.  Go the right way and you will get good advice and approach for your
situation.  Best of luck to you.

Dave Maynard, PE
Gillette, WY

> -----Original Message-----
> From: Don [mailto:dbryant61(--nospam--at)cox.net]
> Sent: Monday, January 03, 2005 7:29 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Assistance With Retaining Wall, Wood vs. Block?
>
>
> Dear Rick,
>
> I designed a Keystone retaining wall of a size very similar to yours in a
> similar location adjacent to a stream bank.  This was in 1997 and it ended
> up costing over $100,000.  This one was so expensive because the
> stream had
> to be routed away from the base, and it required a concrete footing.  It
> also required two or three layers of geogrid (plastic mesh) that ran about
> ten feet behind the wall.  So, at least 8 feet high by 10 feet
> wide of soil
> had to be excavated and backfilled along the length of the wall.  I would
> think that your wall would require geogrid reinforcement as well.
>
> For a timber wall of the size you are describing, I would think deadmen
> would be required.  Pinned to the face of the wall, to the posts and/or
> whalers, will be timbers or steel rods that run horizontal and
> perpendicular
> to the face of the wall, back into the retained soil.  These timbers or
> steel rods will be connected to other timbers, also horizontal, that are
> parallel to the wall.  The parallel timbers are "deadmen", and the
> perpendicular timbers or rods are "tiebacks".  In order to get the posts
> deep enough, you will need some form of powered auger.  I believe there is
> an attachment for a Bobcat that will do this.
>
> Retaining wall failures are fairly common, and, since your new
> wall will be
> fairly expensive, I encourage you to hire a local structural
> engineer.  I am
> sure you are familiar with the "penny wise, pound foolish" addage.  In
> evaluating cost, you also need to look at life-cycle.  If you install a
> Keystone wall properly, it will probably out-live you.  If you install a
> timber wall that is cyclically wet and dry, it will likely require
> replacement, or at least significant repair, in 10-20 years.
>
> Mi dos colones
>
> Donald R. Bryant, PE
> STRUCTURAL INTEGRITY
> 518 Bushnell Drive
> Virginia Beach, VA  23451
> 757-428-6471
> fax 757-428-6473
>
>
>
>
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