Quote:
Originally Posted by wdfifteen
Treated wood that will last any length of time is illegal to use so near the creek.
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That law may be outdated. idk
Treated lumber is no longer cyanide-based.
It's mostly copper-based these days by law:
http://www.usfenceguide.com/wood-fence/
"Most pressure treated wood is treated with a chemical to preserve the wood and protect it from rot and insects. The most common chemicals used to treat pressure treated wood include: Alkaline Copper Quaternary (ACQ), Copper Azole (CA), and, the most recent, Micronized Copper Quaternary (MCQ)."
Wood lumber is crap these days....
Steel posts will probably last ten times longer than wood posts especially in a wet environment.
Steel cross beams will also add to that shear strength from forces uphill.
Fill hollow posts with concrete and rebar.
The post foundations sitting in a drainage base is also needed to avoid further sinking or shifting.
Offhand the contractor's suggestion seems like a good idea to me actually.
(but 5' down is not nearly enough! and that loose hill soil will eventually shift)
The wall needs weep holes near the surface.
And it needs to be angled to allow the OVERWHELMING force of subterranean uphill ground water/dirt to divert and flow downhill.
Engineer for strength, but provide for overwhelming factors.