Big Holes With a Small Auger

[kemartin3]

Sorry, couldn't help the subject line. /forums/images/graemlins/grin.gif I just had to do it.

Anyway, what I'm really interested in is anyone's experience trying to dig multiple holes close together to make one big hole. I'm in the market for a PHD. For the most part, what I need it for is to set fence posts, and a standard unit with a 9" auger will do the job just fine. But I also have two pole buildings to do (probably about 25-30 poles total) that need bigger holes. The books I've read want me to put in 36" diameter holes, but they are thinking about houses and stuff, not a single story shell building like I'm going to be doing. So...what seems to be the trick would be to put three 9" holes close together in a triangle and end up with effectively about an 18" hole. It would seem, in theory, that I could jam some 4x4s or something in the first hole(s) to keep them from caving in when I dig the second and third ones. But, as we all know, sometimes theory works great till you try to really do it. Anyone ever tried such a scheme? Or alternatively, does experience say that for light shell buildings (no floor, metal roof) a 9" or 12" hole is sufficient? I'm in VA, so the ground is mostly clay (unfortunately, the bottom of the list when it comes to its ability to support weight). Yea, I know, just buy a HD PHD with an 18" auger and quit worrying about it. And that is a great answer...if you're loaning your checkbook.

As always, thanks for your help.

 

[herbenus]

I've done 12" holes and felt they were adequate for a shed I built. But my posts were 14 foot 4x4's, not round posts. I dug one hole for planting something where I tried the 3 hole method. But I was planting a shrub or something and neatness didn't matter. It made a real mess. You can count on second and third holes wandering into first hole. But with a manual post hole digger to finish up, it's still better than doing the whole (no pun intended) thing manually.

 

[MikePA]

Hi Kevin and welcome to TBN! /forums/images/graemlins/smile.gif I would be surprised if you'd be able to drill multiple holes that close together. There's enough play in the auger that it would be prone to wander into the adjacent hole if there isn't enough distance between the holes, which defeats the purpose of drilling them close to each other. /forums/images/graemlins/frown.gif

 

[wroughtn_harv]

Welcome Ken,

I've done what you're talking about many times. They mostly were two foot holes six to eight feet deep.

You don't say what kind of soil you've got. My experience is mostly with clay, some of it with rock imbedded.

Since your idea is mostly about using the auger to remove as much soil as possible mechanically I suggest you make a helper before you even start.

Take a piece of plywood or sheet metal and cut a hole in it about an inch in diameter larger than your auger. You flat stuff should be about four feet by four feet for your application.

Then you need to lay out your hole. I'd use some upside down paint like they use for marking utilities. Speaking of utilities I would call and get a locate even if in your own mind there is no way in gawd's green earth anything could be buried there.

I'd make my circle defining the hole. I would then experiment off out of the way with my tractor and find out how close I can dig holes to each other without the auger drifting off into the previous hole. Experimenting like this will not only give you parameters for laying out but tune up your ability to do more, better.

Let's say you find out that all you need is four inches between holes. I'd then lay out my nine inch holes around the circumference of my hole. Then I'd move into the inside and lay as many holes as possible there.

Lay your helper over the hole fartherest from where you're coming in with the tractor. Center the hole in the helper over that hole. Dig it. Remove the dirt from the surface of the helper. Go to the next hole etc and over and over until it's all done.

There's a fella who's making a product for the fence industry that is a helper with a wheel at one end and handles at another. It's for digging holes over grass etc and then hauling the dirt off. I don't think you need something that elaborate for your situation.

Every shovel full of dirt the tractor removes is worth six you have to take out with post hole diggers, I know.

 

[Hoeman00]

Check w/ codes, some hear require 18" hole and a 16" min. footing in bottom (local concrete product place has precast blocks).
Can't u get a bigger auger for your PHD?
Tsc has 12" for $110 or see if u can rent one locally.

 

[Justaplain]

I have had some luck slanting the digger outward. you end up quite large but as the man says "every one the tractor digs is worth many by hand" bcs

 

[fractal]

I helped a neighbor plant some avocado trees last fall. Drilled three, nine inch holes with auger in a triangle pattern. Sometimes they crawled in on each other in which case I moved a bit and tried again. He cleaned it up with an old fashion post hold digger. Took an hour and a half to dig holes for 50 trees (150 holes) and took him another day to clean them up by hand. He had spent 4 hrs digging one by hand to half depth when I got there that I finished with the auger. Worked just fine in his dirt which is mostly fill so easy to dig. Woulda been a real pain in clay/rock but definately faster than doing it all by hand..

 

[varmint]

For what it's worth, when I had Morton put up our pole barn, I watched pretty carefully, and since they do a first class job, this may help you: Their "poles" were actually three 2x6s- since the treatment can penetrate into a 2x6 better than say a 4x6- fastened with stainless spikes. Of course, they had a purpose-built digging truck with about a 24" auger, but a 12" should get the job done. They dumped 2-3 bags of concrete mix into each hole, dry, and then some water, and just let it go... Building is doing fine, but then, it's not 40 years old yet.

 

[kemartin3]

Varmint,

When Morton was putting up your building, did you happen to notice what the treatment level was of the "poles"? I'm having a horrid time finding anyone locally who can source .60 lb. CCA treated poles. Everything that I read in books says that is the minimum for embedded structural poles. On the PHD, I finally bit the bullet and ordered an 18" auger. It was $275, but figured into the price of two barns it becomes a nit. And it will sure make planting trees easier. /forums/images/graemlins/grin.gif

Kevin

 

[cisco]

I put in a front fence line recently, and at the gate site used 500 lbs of concrete (quikcrete mixed laboriously in a wheelbarrel) around each of the 2 poles (6X6 CCA treated, buried 4' into the ground, and all the rest of the poles in the front fence line had 200 lbs. of quikcrete - this sucker won't move - I hope). To make room for the concrete at the 2 gate poles, I used my 9" auger in a triangle pattern, keeping the 3 holes just far enough apart to get distinct holes that were separated by about 6 inches of dirt. Then I put the auger back in each hole, and just slowly inched the tractor in the direction of the center area between the holes, with the auger running - it collapsed the intervening dirt wall without seeming to stress the auger or tractor. So, then I had one somewhat irregularly shaped large hole, with very loose dirt in the botton (the collapsed central area) to shovel out. Kind of labor intensive, but there's no way my PHD (or tractor) could handle more than a 12" auger in the firm soil I was working in, and for all I know my wife will select wrought iron gates (me, I think a "cow gate" looks just fine)- so the gate poles had to be stable.