[TowerTalk] Crank-up base

[Mickey Baker]

Hi, Mike,

Depending on where you are geologically, "undisturbed" soil may be
difficult to achieve. I was lucky in that my house is on a US Corps of
Engineers built muck island, retained on all sides by concrete piling
retaining walls. I had a soil analysis did years ago before I installed a
swimming pool. The muck was stable enough for 48 hours to dig, form the
top, inspect, and pour concrete. I kept a pump running at the bottom of the
hole the entire time, and I kept people (and dogs) away from the hole.

If you're in fine "sugar sand" no matter what you dig, your hole will turn
into a modified cone, the small end being at the bottom of your hole.

I have seen plywood forms used and withdrawn while pouring - this is common
in sandy or wet locations. A good concrete contractor will build a plywood
form with attachments that enable a backhoe/front end loader to lift the
form out DURING the pour. This takes some skill or you're going to get the
form stuck in the concrete. It is not a "do it yourself" technique.

73,

Mickey N4MB
Fort Lauderdale, FL