Cleaning out and reusing some old concrete fence post foundations?

ponytug · Mar 3, 2022

We are repairing some old fencing along the driveway, and the old fence of 8"x8" posts turns out to be anchored into 16"x 48" foundations of concrete surrounding some now insect eaten 8x8".

Could the remains of the 8x8s be augered out with a six inch auger? I just need them mostly out, not perfectly clean.

Thoughts from the auger experts here?

Any better ideas?

All the best,

Peter

Lnk · Mar 3, 2022

ponytug said:
We are repairing some old fencing along the driveway, and the old fence of 8"x8" posts turns out to be anchored into 16"x 48" foundations of concrete surrounding some now insect eaten 8x8".

Could the remains of the 8x8s be augered out with a six inch auger? I just need them mostly out, not perfectly clean.

Thoughts from the auger experts here?

Any better ideas?

All the best,

Peter

Put an accelerant and burn them out. Drill a hole down the center. As long as you don't make an inferno, the concrete should be fine. You may have to clean out after.

BigDaddyEureka · Mar 3, 2022

I like Ink's idea there.

IF the posts are REALLY REALLY ROTTED, then yeah the snall auger should chew them right out. Hit any hard spots though, and it will be the Mad Hatter's wild ride!

PowerTracManiac · Mar 4, 2022

I have had some success boring out a center hole and then adding some charcoal briquets into the hole. The charcoal kept the center burning and the wood burned itself out from the center.
Once cleaned out I suggest you look into the expanding foam method of setting the new posts. The expanding foam could be poured into the relatively clean hole (doesn't have to be perfect) and the new post set with that foam. I think that would be very strong and would keep that new post nice and tight in the hole.

oosik · Mar 4, 2022

I DO like the idea PowerTracManiac suggests. Plus - if the big 'ol concrete blob get hooked tight on a PTO driven auger - look out man.

m5040 · Mar 4, 2022

Sounds like more work they just mixing cement that will conform to the new hole.

ponytug · Mar 4, 2022

m5040 said:
Sounds like more work they just mixing cement that will conform to the new hole.

Fair enough, it is a bit of work.

My issue is that I have about sixty of them, and as they are so deep, and heavy, extraction would be something of a project. Are you suggesting that I move over 4' and put in a new hole with new concrete?

This project has been a head scratcher for me for quite sometime. I have never done something like it before. The bigger picture is that the 8x8"s are on one edge of the driveway and hold an offset 2x10" board to form a "guardrail" at the top of a steep slope that you wouldn't want to drive down, so I would like to have them in reasonable shape.

There are buildings at the bottom, amongst other things. A solution that is stronger would be better, ditto deeper is better, as it would help anchor the uphill driveway.

My original thinking "Plan A" was that I would drive a new 8"x8" down the old hole, but I am beginning to realize that isn't likely to be easy, or routinely successful... "Plan B" is pipe, if I can locate a reasonable source for 5-6" pipe. "Plan C" is using I beams. (Galvanized?) A lot depends on pricing. If I can't get a reasonable source for the parts, I will probably just do a concrete wall. My attraction for steel over wood is the rather short life of some of the 8x8s that I used to hold up the three board fence along the driveway. In less than five years a number were already rotting out.

Advice is always welcome.

All the best,

Peter

ponytug · Mar 4, 2022

oosik said:
I DO like the idea PowerTracManiac suggests. Plus - if the big 'ol concrete blob get hooked tight on a PTO driven auger - look out man.

Yes, I have wrestled that monkey before. My sister wanted some posts in her backyard, and we rented a two person auger. We powered it up and promptly hit fractured rock, which sent us flying. The professional crew that did the front yard brought in man portable equipment that drove a 24" auger through it. It took them two or three weeks.

I would probably do it with a hydraulic auger attached to something big and heavy so the auger would hit its pressure relief before tossing anything. I thought I might start with a 2" pilot auger just to see how bad it was.

All the best,

Peter