Re: Changing polar alignment...Ground shifting?


Mike Dodd
 

On 12/29/2020 10:10 PM, deonb wrote:
4-6 */degrees/* of drift? (Not minutes?).
That's what I was going to ask. If it's off by that much, you should be able to put a level up against the pier (or just look at it) to check if it is still plumb.

It seems unlikely that rain could have shifted a 3x3x6 concrete block that much. That's 8,100 pounds of concrete -- a huge mass!

Was there an earthquake in your area by chance?
That would be the only thing that would move such a mass. Where are you located?

I've built two concrete piers without any super-duper footers. The most recent is 12" in diameter, rising about 66" above the ground, and sunk about 40" in the ground with a 24" "blob" of concrete at the bottom for a footer. I used a power earth auger to dig the hole, then hollowed-out the bottom for the "blob" footer. Definitely nothing special about this pier, but it hasn't moved in four years. It DOES have an observatory around it, so it's sheltered from rain.

Tell us more, please!

--- Mike

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