Post holes in heavy clay and limestone

[GabeTX]

Hello,

I'm currently planning a fencing project; I'm looking at around 2600' of high-tensile woven wire. Around 100 line posts that need to be 3' deep and around 20 end posts that need to be 5' deep (urgh). I'm near Ponder, TX in Denton County.

I've built one smaller "backyard" fence, so I know what I'll be digging in. I have about 2' of rocky, heavy black expansive clay with solid limestone underneath that. The limestone is soft enough that I can slowly work through it with a digging bar; the 3' deep holes for the backyard fence took a few hours each with a digging bar and a clamshell digger.

From what I've gathered so far, my options are:

1. Suck it up and dig them out by hand. It'd take a few months of evenings and weekends, but I know I can afford it. /forums/images/graemlins/smile.gif
2. Rent a Bell-Tec TM-48 with a bullet auger for 3 days. This would cost nearly $1400, but should get the job done relatively easily.
3. Buy a long chipping hammer bit (I found a place that has them up to 6') and rent a compressor. Cost would be around $500 for a weeks rental and $50 for the bit, plus a couple hundred for some sort of hitch so my tractor can drag the assemply around. I have no idea how long it would take to dig a hole with the thing, so I don't know how long I'd need to rent it?
4. Buy a high-quality 3pt post hole digger (I'm looking at Danuser) with a carbide-toothed auger. This would cost as much as renting the Bell-Tec, but I'd be able to keep the implement at the end. However, I don't know if a 3pt post hole digger, even a nice one with a good auger, will work in limestone?
5. Pay someone with better equipment to dig the holes for me. I have no idea how much this would cost.

Am I overlooking anything? Any advice? Will the Danuser auger with their "hole digger head" work in limestone? A rough estimate on how quickly a chipping hammer can break through limestone? Ball-park figure for what I'd pay a pro to do the post holes?

Thanks!

 

[MikePA]

I'd vote for 2 or 5. /forums/images/graemlins/smile.gif

Before I selected Option 4, I'd call Danuser and ask their advice. I imagine you'd need a digger that had downforce.

From someone who installed 227 posts last spring. /forums/images/graemlins/grin.gif

 

[jinman]

Gabe, were you planning on running that TM-48 with your Jubilee? I'm not sure your tractor can handle that. Why not rent a Bobcat with a front auger that has downpressure? That and a carbide tipped auger should work.

I think the TM-48 could also be the way to go. You might dig as much as you can with a regular auger and then bring the TM-48 in for the hard part only. That might save you some rental time.

 

[GabeTX]

The TM-48 I was looking at renting comes with a big 50 hp tractor with all the necessary hydraulics (the $1400 for 3 days I mentioned includes the tractor rental and delivery too).

I forgot to mention that I did price a skid steer with an auger; if I recall it was around $1200 for a week, including delivery. I should probably shop around a bit more for that rental, though. Lots of rental places have skid steers. I was also unsure if the auger the skid steer comes with would be able to handle limestone. I'd have to research this option more...

I hadn't thought of using a regular auger to dig out as much as I could before hand--that's a good idea. I can borrow a regular auger easily enough and it ought to cut down my rental expenses quite a bit.

Thanks!

 

[DocHeb]

Digging in clay/stone gives preference to the skidsteer, with it's capability for downpressure and reversing the auger.

 

[Farwell]

Gabe,
I like number 5. Do some serious checking around and get some bids. If you hire someone that really knows what they are doing, what they are getting themselves into and has the right equipment, I think you could be way ahead of the game, especially with the amount of fence you plan on putting up. With the amount of work the post hole digger will have to do and the ground you have, there is probably going to be some broken or worn out equipment.
Hard pan experience in Northern California.
Farwell

 

[wroughtn_harv]

The skid steer idea won't work.

One, a skid steer is made for lifting. It only has a little more down pressure then you can get with a three point.

Two, rental yards don't have good augers for rock, sorry, but they don't.

I have a five foot bar and a six foot bar for the sixty pound hammer for digging rock. It's doable, a lot of work, but doable.

I have a skid steer. I also have rock augers. They're not cheap, not at all. Plus when you have the rock auger on the skid steer digging through the clay is like with the bottom of a telephone pole. It instantly clogs up and won't dig for squat. So I have to go through and dig through the clay and then follow back with the rock auger digging into the rock. I also put about six hundred pounds of tractor weights out about three foot off the head of the auger motor to get some down pressure.

The easiest way to dig your holes is with a checkbook, same tool I use for painting my house. For about seventy five dollars an hour you can have an auger truck knock them out. Just keep in mind that charge is the same if they're waiting for you to mark a hole or digging one. So if you go that way be sure and have all your holes marked and thr right of way ready. Also be sure you have all the utilities marked or cleared. The auger truck won't start up without them. And you need at least forty eight hours notice. 1800 DIGTESS

If you want to do it yourself then I suggest you dig your holes to rock. Then you go down to your rental yard and rent a compressor with a rotary hammer. You'll have to buy the bit. I carry three and four inchers on my truck just for those occasions.

The rotary hammer will go through the limestone like grass through a goose, hot knife through warm butter, bad wife through good money, it'll happen.

You then set your post in the limestone with a product you can get a fence wholesaler. Closest to you is on 121 between Frisco and Lewisville, northside of the road by the concrete plant, Northside Fence Supply. It's called Quick Rok. HD or Lowes also carry a similar product from Quickset. It's anchoring cement.

Then you use regular stuff like Maximizer for the clay.

Hope this helps.

 

[GabeTX]

Thanks, Harv, that helped a lot!

I'll scratch off the buy/rent an auger options (skid steer or 3 pt hitch) as unworkable.

I was planning on using wood posts (that way I can build the braces myself; plus I like the look), so a 4" rotary hammer wouldn't work.

I hadn't heard about the auger truck option before; that sounds real promising. Can you tell me a little more about their capabilities? I'm sure the rigs vary, but roughly how much time should I plan on one of them needing to dig a 12" x 3' hole for a line post? I'll definately have all the hole locations and utilities marked before they come. I'm guessing that going down to 5' for the braces won't be a problem? Would I save them much time by digging down to rock before they come? By "having the right of way ready" do you just mean free of brush and debris, or is there something else I need to worry about?

Depending on how quickly they can put a hole in, they may end up being cheaper then the other options! The $1400 it would take to rent the Bell-Tec for 3 days (24 hours) would pay for 18 hours of the auger truck at $75 an hour...

 

[EastTexFrank]

Oh my poor back hurts just thinking about this one and we've been running fence at the farm, of and on, for the past 3 months. Fortunately our ground is a lot easier than yours but still ....

The only thing that I can think of to help is, and Harvey correct me if I'm wrong, that 5' is a long way down to set a end post. If the digging was easy then it wouldn't be a problem but if you're going to "tack" the bottom with cement and then fill around the post with more cement and they are braced properly, I would think you may be able to get by with 3' of penetration. Just a thought and I'm willing and waiting to be corrected but it might save some work, time and money.

If it's as bad as you say, I'd be tempted to do as Harvey mentioned, break out the check book and get someone in with a truck mounted auger to drill them. I think it would probably be worth it in the end. Something similar to those used by the utility companies should be able to knock them out in a "short" time. Using a breaker bar in that many holes will get old in a hurry.

 

[GabeTX]

Well, the reason I'm sort of set for 5' for the braces is because that's what the manufacturer of the fabric I plan on using recommends. There'll be 17 horizontal high-tensile wires stretched between each set of braces, so pull-out could be a big problem. I described my soil (and limestone) to the manufacturer and they didn't back off the 5' minimum depth, so no luck there. /forums/images/graemlins/smile.gif

Of course, the upside to all this is that the line posts can be 25' apart...

I'm planning on using this stuff:

http://www.staytitefence.com/products/17-75-6.htm

Their construction specs for wood end posts:

http://www.staytitefence.com/fence-design/pdf2/6'woodbraceassembly.pdf