Then I hit ledge - french drain continued

[Hilary]

Since you had good advice on the first part of the project, I’m back about the issue of draining the area in my hayfield.
Perforated pipe and sleeves acquired. Backhoe arrived. I learned to run the backhoe and was making good progress on a lovely trench where the water followed me. About 50-75 feet over, just before the field slopes seriously downward and I’d be home free, I hit the reason the water pools there. A ridge of ledge about a foot under the topsoil. That is one of those noises that once you learn what it sounds like you know exactly what it means. You don’t need to wonder, how big is this rock. It’s part of the rest of the world.

Of course the guys in the family immediately brought up blasting, but as I really only need a 4-6" channel for the pipe to pass through, would a jackhammer be a more reasonable option?

How hard is it to jackhammer into granite? The rock appears to be about 18" in width, and I would need to go down about a foot, to be sure to have the right pitch.

I was so excited when it seemed to be working… No one will be hiring me for my speedy backhoe skills but it was pretty fun to run.

Pictures here:

https://www.facebook.com/hilary.deangelis/media_set?set=a.10212494018658627.1073741861.1627302961&type=3

[Horseman15]

If you’re in granite good luck with a jack-hammer. Depending upon the quality of the rock it may break however. Since you only need about a foot over an 18 inch span here’s what I’d do.

Option 1 Rent a gas powered cutting saw with a diamond blade. Cut grooves in the rock and make little slices, then use a jack hammer to break off the pieces.

Option 2 They make jack-hammer units that mount to the back of the backhoe where the bucket is. You simply remove the pin holding the bucket on, disconnect the hydraulic hoses (they should be quick attach couplers) then attach the jackhammer unit. These things are pretty Stout and will do some serious damage. But they’re not all that cheap and require a little effort to install. On the plus side you have the full weight of the tractor pushing down on it and the hydraulic force of the tractor hydraulics.

Personally I’d go with option 1. Running a jack-hammer is fairly easy. I’ve used them numerous times over the years. The biggest trick to running one is remembering that A) get the biggest one you can drag around by yourself and B) don’t push on it or try to help/hold it, just keep it in the basic position you want it in and let it do it’s thing. The other thing is always have at least 3 if not 4 extra bits as they WILL get stuck and sometimes it takes another 1 or 2 bits to break them loose. Rent a tow behind air compressor and try to get the biggest jack-hammer you can drag around.

[Hilary]

I have used the method of making slices and then knocking them off in wood - I like that idea.

[Bluey]

Here, rental equipment places have rock saws of all kinds, some as attachments, some self contained in a trailer you pull to the place, etc.

Here are some of those:

http://www.rocktools.com

Try going to your rental store and see what they have, the same you would rent a compressor and jackhammer.

Those are in demand here by contractors doing work for utility companies, like those laying phone lines.
At times you have to wait for one of those to be available.

[Horseman15]

@Bluey I didn’t even know they made rock grinders like the ones in the picture. That thing rocks!! I wonder what the GPM flow from the hydraulic pump is for that thing!? That would be perfect for making a trench though