Post Hole Digging Problems

[RMFarm]

I've been lurking around this site for some time now and have gotten very good advice from reading other's posts.
What I need to find now is some advice from someone (or many) who have put in fences in VERY rocky soil.
I'm building a horse fence. True rough cut 5x5 hemlock posts (to match store bought 6x6) on 8' centers with 16' 5/4 hemlock rails staggered to span two posts. I planned on setting the post down 3' no cement, just tamping. I'm using a Lienbach 7300 with a 12' auger.
I'm in the Catskill mountains and the problem is ROCKS!
Now I'm not talking a hole full of little four to six inch puppies. (That's the best case scenario.) I've pulled several 14" flat stones out of ONE hole. So far I haven't gotten one past 2 1/2'. (Seems to be a ledge there.) I've gotten pretty good about stopping before I break the shear bolt. (Still usually break at least one a hole.) And I work with a two inch pipe and a breaker bar to remove the rocks. The problem is, working alone it sometimes takes me over an hour a hole to set a post. (So far maybe one of six goes will go in under a half hour.)
I have about 60 posts to set for my first fence and another 60 waiting. Am I going about this wrong? Should I have gotten a post hole pounder? Or is this just normal for this area and I'm complaining too much as usual?
Any comments (snide ones too) will be appreciated.
BTW: At 2 1/2 feet I usually hit ground water, too!

 

[SPYDERLK]

Sounds like the problem is normal for your soil. A post pounder might work if you 1st drove a skid steer demolition hammer into the ground to make a 3 inch pilot hole. These are hyd driven impact hammers and should be able to go thru moderate sized rocks leaving them broken so your post would be able to penetrate.
larry

 

[jinman]

I think you need to make friends with these folks. It's a friendship that may be expensive, but so are women, and that doesn't stop us.

Belltec Industries

 

[wroughtn_harv]

It sounds like you've got layers of rocks. That isn't good. It could be a lot worse.

Worse is when you have lots of boulders mixed with sand. When you drop down a post hole digger powered by anything less than a ten wheeler rig the auger will jump and dance and get the hole out of line. Hand digging with with post hole diggers can only be compared to using straight pins for chop sticks after a forty day fast.

What I've done in layered stone is take each layer for what it is. By that I mean some layers are thin and can be gone through with an auger with little problem. Some layers are thick and need to be broken through with either a jackhammer or a hydraulic hammer on something like a skid steer.

When your auger won't go any further then you pull it and go after the rock in a hard place with your digging bar, jackhammer, whatever. When you're through that rock then go back to the auger because a lot of the time the really thick stuff is separated by the thin stuff which your auger can handle.

You'll probably find that there's a pattern. When you learn it then you pick up on when to just bear down with the auger or pull it and get serious with your getting in shape one way or another routine.

The good thing about this kind of digging is your fence will stay straight for a long time. Here we have expansive soils that put the big X in expansive. It's easier to dig than in any kind of rock. But your fence posts won't stay straight because the soil is in a constant state of movement.

Count your blessings.

 

[Sniggle]

I finished 120 holes myself this spring, and had a fair amount of rock (hard limestone rock ledges).

Here is my advice, for what it is worth:

- Obviously, try to get as deep as possible with your post hole digger. I found that even with no rocks getting below 2.5 feet was asking for a stuck auger, but I was dealing with sicky thick red clay.

- If you hit rock, take out your digging bar (I referred to mine as my instrument of persuasion) and see what you can get loose/knock out.

- You will know by the sound and feel of the bar as it hits the rock if you have any prayer of making a dent. Don't kill yourself if the bar tells you it can't make headway.

- If you are down 2 feet or so, depending upon your soil (my heavy clay can hold up a post pretty good), consider yourself lucky, plant the pole, tamp well, and cut off the top to match.

- If you are less that 1.5-2 feet, you really have 2 choices, concrete or moving the hole. Moving the hole obvioulsy is a pain when using board fencing.

 

[PA hayseed]

I think you need to make friends with these folks. It's a friendship that may be expensive, but so are women, and that doesn't stop us.

Belltec Industries

exactly....not all augers are created equal.

The other posters have given you good ideas/tips. A good auger is worth every penny. I live in central PA, so I know what your going through. I either hit limestone, shale, white clay, sandstone, etc. Unless you got a rock coring rig, some rocky areas cannot be dug through with a PHD. Trust me, I worked on a hydro drill rig, until I got an easier job. We dug around state college, PA and hit VW size limestone boulders barely below the surface.

I strongly suggest concrete if it's solid. You won't have to worry about frost heave if it is that solid. couple of bags of ready mix on your tractor and your good to go.

good luck

 

[Western]

x's 3 on the Belltec.
I rented one on a tractor for a 1200' pipe fence, every 8' was a post and we never got through the table rock!. worst job I've ever had as far as rock goes and I have dug allot of holes. This was the first time I had to rent a rock digger to use personally and it work better than expected.

I have two jack hammers, one electric and one air. As I get older I like them less, they get the job done, but its like hugging the goal post and letting the Cowboys defensive line take shots at ya

 

[Johndeere3720]

Have you tried a smaller bit? My grandpa builds pole barns for a living so when the 12'' auger cant break through, he uses the 9'' auger. Maybe a bobcat 9 or 8'' auger with rock bits might help.

 

[RMFarm]

I finished 120 holes myself this spring, and had a fair amount of rock (hard limestone rock ledges).

Thanks for all the great advice. I've dropped a few more posts since this thread started. I've been busy with other things and can only work on the fence a few hours here and there right now. It is still taking me like an hour to dig and set a post on a bad hole (and most to this point seem to have been bad).

So I guess I just have to expect to spend about 60 hours setting the posts for this fence. (About 500' of fence with posts at 8'.) That's FAR more time than I had figured. Was I just being naive? Is this the kind of time you guys need to put in when working in bad rocky soil? (How long did your 120 holes take you Sniggle?) Or is this just my inexperience and/or bad luck?

 

[Sniggle]

RMFarm,

I figure it took me on average about 20-25 minutes a hole to dig, place post, and tamp. Some holes took 30-40 minutes if I had to attack it with the digging bar and mix/pour concrete. I would set a goal of, say, digging 10 post holes on a line and work till I accomplished that.

I actually started digging holes last fall, but really got serious in late February.

I did have one advantage, that being that I was using a tensioned fence (Ramm Fence) so my posts did not have to be exactly X on center (in my case every 12 feet). That alowed me to try to find a better spot on my line 1-2 foot on either side of my original hole if I hit bad stuff just below the surface.

Slow and steady, grind it out, and before you know it it will be done.