Sonotube Foundation Construction

[spats]

What is the proper way of constructing a round concrete pier foundation where the top is above grade, like for a small light pole foundation? My primary concern is the lateral resistance of the foundation. My understanding is these types of foundations are normally constructed by auguring a hole (say it's 4' deep), and forming with a sonotube. I assume the sonotube would only be used to form the portion of the pier above grade, so you're casting against undisturbed soil... or is it really "undisturbed" when you use an auger? Even after augering, it's probably necessary to clean up the hole of loose soil, and consolidate the bottom in some manner. If you were writing notes for the proper procedure on your drawings, what would you include, or should the structural engineer not dictate means and methods? I want to make sure I have the lateral resistance required.

 

[JedClampett]

Besides cleaning out loose dirt, we usually don't require much preparation. And I suspect thae contractor doesn't do a good job of that. The sides are considered undisturbed.
I've designed a bunch of these. Between the mass of the concrete and the lateral resistance of the soil, never had an issue.
Think of it this way; You have a 5" x 5" 12 gage aluminum pole. You have a two or three foot diameter piece of reinforced concrete 4'-0" long. What's going to fail first?

 

[Splitrings]

ASABE EP486 Shallow Post and Pier Design. This reference will help.

 

[paddingtongreen]

The sonotube is used for looks at and above grade. You rely on the concrete being placed directly against the soil in the working part below grade.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin