This weekend I was digging the trench for the water line up at the cabin using one of those small kabota tractors with a back hoe.  Things was going pretty good until I hit this large 4 foot rock.  All the other rocks in that section was 1 to 2 feet.  I tried to dig around it but it wouldn't give.  It is right between  two sets of trees and to dig it out I would probably have to take out some of the trees which I would hate to do.  They are red leaf maples.  Really pretty in the fall.  I am looking for some ideas here on some good ways to get it out that won't cost a lot.  I don't have the wattage on the solar system to run a jack hammer,  explosive aren't allowed with out a permit!! And it would run $500 to get a rig big enough to dig it out.

Any ideas?

Gas powered jack hammer.

Is there a reason you can't pick a different place to run the line? A 4' rock doesn't sound like much trouble to go around.

Bonfire and cold water?

The following quote, which I heard a lot back when I was in the Army (36th EOD) seems right at home in this thread:

QuoteThere is no problem which cannot be solved by a suitable application of high explosives!

A nice shaped charge oughta tear right through that sucker.....

Drill holes in rock along the line that you want it to fracture.
Drive wood pegs into the holes.
Soak the pegs with water.
The pegs expand and split the rock.
This is the technique, but I don't know all the gory details.
You may need to do a little research to fill in the details, but it should work.

When I was a kid, I helped my foster father with the same problem.
I ended up digging a pit under the rock by hand and letting the rock
fall into it so the sewer line could go over it. This was done in the wetlands of
Connecticut in the middle of the winter. I can still remember how cold it was.
Bruce

Or you can use one of those expansion demolition slurries (like Dexpan Betonamite or Sylentmite).

I ran into a similiar problem 30 yrs ago when I was digging out my uncles basement. I found a rock about the size of a residential garbage can and we had no way to get it out of the basement. He just had me dig a really deep hole along side it and we used a come a long and high lift jack to roll it into its new resting place!