I’m digging a new sprinkler system before the weather here gets too hot to do it. Part of the fun is laying a sixteen-foot tunnel out of one-inch Schedule 40 PVC under the driveway.

[Update at 4 PM EDT]

In response to the question in comments, I use a hydraulic drill. The soil is sandy (this wouldn’t work if it were rocky or clay). Attach a straight nozzle (Home Depot sells them just for this purpose) to one end of a twenty-foot length of PVC, and a hose connector to the other. The jet of water blasts a hole ahead of it to allow it to be pushed underneath the concrete. Unfortunately, the longer the run, the more friction on the sides of the pipe, particularly from the junction that sticks out, and the last few feet require a hammer to get it all the way through. I don’t think I could manage a wider driveway than I have. Once you’re all the way through, cut off the hose connector and nozzle, and hook up the pipe to each end.