[TowerTalk] Looking for some foundation advice

[Steve Maki]

On 05/27/20 19:15 PM, Grant Saviers wrote:

> Actually it is ok to pour concrete into a wet hole if the concrete is 
> pumped in from the bottom. The water rises right out.  Not ok to drop 
> concrete into water.  The mix plant, pumper and driver know how to 
> adjust the mix a bit.

Hmm - that's not my experience. When we (drillers hired by me) install 
caissons for tall monopoles and self supporters with 30'-50' deep 
caissons, they just dump the concrete in. They use temporary cylindrical 
forms to prevent cave-ins, but pay little attention to the water down 
there. These operations are always monitored by 3rd party engineering 
firms. On the reports I usually see *freefall concrete placement*.

> Or have a PE design a different base, there are all sorts of 
> alternatives, plates, piers, wider and shallow, etc.  As long as the 
> base resists the overturning moment and shear. The stock foundation UST 
> wet stamp is on the web so should be a easy and quick job for a PE 
> (unless they want a soils test, which in theory...  but local knowledge 
> of conditions often is acceptable).

Agreed. A suitable foundation can be designed for above ground placement 
if you don't mind the ugliness and the concrete cost. The key is to get 
it engineered properly.

-Steve K8LX