I posted my question regarding compacted vs.undisturbed backfill two
days ago. During that time I have received over twenty responses,
mostly directly. I would like to summarize those response here and
in so doing, thank everyone who took the time to share their
knowledge, experience and opinions with me. In priority order:
1. Do what the P.E. says. He has done the calculations and his
license and reputation on the line. If he says compacted soil is
acceptable for (under his specifications), than you can be assured
that compacted backfill is acceptable.
2. Properly done, compacted soil is as strong and in many cases
stronger than native undisturbed soil.
3. The specifics of soil compaction relate to the types of fill
material used, the level of compaction and the depth of each
compaction step. A typical example might be to specify well-graded
gravel, 95% impact compaction and minimum 8" steps. The P.E. of
record is responsible for these specifications.
4. What is not acceptable is to simply dump the excavated soil back
in the hole and drive over it a few time with a back-hoe tire which
is done more often than one might think.
In my friend's case, he contacted his P.E. who approved the used of
backfill so long as it met industry compaction standards which he specified.
I want to thank everyone who contacted me. The knowledge that is
available on this forum is absolutely astounding!
Dick
At 11:53 AM 4/27/2009, I wrote:
>A friend of mine is installing his first tower. It is a US Tower
>HDX454. (I thinks that's the right number. I have an HDX572 and his
>is the next one shorter than mine.)
>
>He had the tower specs checked by a local PE for the requisite wet
>stamp needed for his building permit. The PE calculated and
>specified a tower footing of 5'x5'x7.5' in undisturbed soil.
>
>His contractor dug him a 10'x10'x8' hole and is going to put a
>5'x5'x8' plywood frame in the hole enclosing the rebar cage. He is
>then going to fill the frame with concrete and when it cures is going
>to remove the frame and back-fill the hole with compacted soil.
>
>My friend is being told that properly compacted back-fill is the
>equivalent of undisturbed soil. Is that true??
>
>Dick
>--
>Dick Flanagan K7VC
>dick@k7vc.com
--
Dick Flanagan K7VC
dick@k7vc.com
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