Rebel1 wrote:
As of 4:30 pm today, I've completely exposed the pipe that's not under
the walkway. There are 52" between the walkway and the house, 52" under
the walkway, and 17 feet further on to the manifold.

My concern with water blasting to make a tunnel is that it will make a
hole larger than the OD of the pipe. Over time, the soil above the
tunnel will settle, leading to a depression in the walkway across the
width of the walkway.

Thanks to all for your excellent ideas and comments.

Will post again tomorrow afternoon, after the guru tells me his plan and
comments on my idea.

Ray

The pro who over the phone said he would snake a 3/4" pipe under the
walkway through the existing 1" pipe just left. After seeing there was
only 52" under the walkway, he changed his approach to what I had been
considering. (For a much longer distance under the walkway, he would
have stuck with his original approach.) Just use a coupler, without
clamps that would drag along the soil, to connect the new 1" pipe to the
old and pull the new under the walkway by grabbing onto the old; the
coil of new pipe would be on the house side. I don't know why the
pulling wouldn't cause the coupling to separate, unless someone was also
pushing from the other side of the walkway.

He's coming Monday PM to do the job. Original price, $150, to replace
27' of pipe. I tentatively got him down to $125, but he said it was
really dependent on the difficulty of going under the walkway.

Ray