On Tue, 16 Oct 2018 14:12:01 -0400, John H.
wrote:

We've had a lot of rain.

I bought a new post for the mailbox. Had Ms. Utility out to mark the underground lines. The new post
needs to be back from the curb 24" to allow for 6" of space from the street and 18" of mailbox. I
had a rod marking the location I wanted to dig. When I went out to look this morning, the utility
marker had put a yellow line right through the spot I wanted for the post. The gas line. Now why the
hell, given the USPS requirements, would the gas company put their damn line right there? Jeeez!

But, here's the quandary. I need a hole 24" deep for the post. About 15" down, I hit the new water
table from all the damn rain we've been having. Keep digging. Now I'm down 24", but the bottom 8-9"
if full of water. I'm thinking if I dump a bag of sacrete down there it'll just become soup. Ditto
with putting dirt down there. As the post and the mailbox are quite heavy, it's got to be set pretty
firmly.

****.

You can either use a tremie (a pipe that goes to the bottom and allows
the concrete to get there unmolested) or just dump it in and get on
with your life.
Considering mail box posts are not bridge pylons, I would just dump it
in (mixed pretty stiff). Dump it in large quantities at the same time
and it will just displace the water and be fine. Sack concrete is
typically 3500 psi gravel mix so even if you lost 90% of the strength,
it would still hold a mailbox post until the post snapped.
The reality is I doubt you lose 25% and less than that if it all goes
in one slug. They place concrete under water all the time.