Running a sprinkler line under a sidewalk?

[postacct]

When new sidewalks were put in our area, the contractor extended the sprinkler system under the sidewalk to cover the swale area. But he connected that area to just one of the existing zones and there's not enough oomph to get full pressure all the way to the end. I want to split the added line and connect part of it to another zone, but to do that I have to go under the sidewalk. The fill that was used for the swale area has LOTS of compacted rocks which makes it difficult to even dig a hole to plant something. How do I get new piping under the sidewalk?

[hallerb]

dig hole on either side, use drill bit with extensions to go under walk. try to not remove more dirt than necessary to avoid sidewalk cracking

[Robert Neville]

Three choices:

- Use a water drill. (Won't work with lots of rock in the soil).

- Hire a horizontal directional drill (HDD) company (expensive)

- Break one section of the sidewalk, lay the pipe, repour the sidewalk square. (Labor intensive, but cheap if you provide the labor)

[hallerb]

you can dig a hole on either side and use drill bit extensions with masonary bit to get under side walk

[N8N]

You've gotten good replies to the question you asked, but I have to ask... why would you need to go under the sidewalk to do this? couldn't you just find where it connects to the existing zone and dig there, then take a new run back to your manifold and cap the existing zone where it tees off under the sidewalk?

nate

[hrhofmann]

I have used a garden hose running full force to tunnel under a walkway, just be sure to go low inough to avoid whatever gravel is under the sidewalk (hopefully)

[mm]

Gravel? Under the sidewalk?

You remember my posts years ago about lifting up a square and getting rid of tree roots. (Well maybe I didn't post on this). Until now I didn't notice that there was no gravel.

(It's only cracked in one place, however. Of course one is not zero.)

[Robert Neville]

That's a good idea... To the OP's original question, if you cut the crack joints, you might be able to lift the slab enough to route the pipe underneath...

[mm]

Well, it was/is a good idea, but it was helped along by the sidewalk contractor, who had one of his guys cut the single square away from the rest of it (It had cracked on the line at the other end), with his gasoline powered saw which I think had a diamond-tipped blade.

The sidewalk was about 3 or 4 inches thick, and lifting the single square was pretty hard. Anything longer would have been very difficult.

While I'm here, the first time I lifted it up, I got a friend to help me and a friend to help me put it back. I thought once would be enough but I hadn't cut out enough root. So I learned to do it alone, by using 4 or 6-foot 2x4's as levers, lifting it only about 4 inches, with 4x4x as fulcrums and by rowing the 2x4s like rowing a boat, one at ttime, I was able to lift the square and move it 4 feet to the side and rest it on other 4x4s.