Posted: Jun 17, 2008 5:01 pm
It's actually a bit cheaper than a traditional, open trench replacement. Certain factors may prohibit it as an option but it's a pretty simple thing. They have this pneumatic, rocket-shaped end that they winch through the existing line which steps up in diameter (they have different sizes down to 4") and a hydraulic line sends pulses to the head that shatters the existing pipe and pushes it out of the way. As the head is pulled through the line, it also is pulling the new pipe through. Usually, backfill of the original line will allow for some small expansion. You might have troubles with pipe bursting if other utilities are right next to it as the pulses do put out some small shockwaves, but nothing that bad. If it's a pretty straight shot and you aren't on a party-line, you should be able to get the whole thing replaced with only a minor excavation at the street for cheaper than an open trench. You might also, initially, see some surface bulging of the new line - depending on how deep the old line is, the materials used for backfill, etc..
I don't know how it is where you live, but in Portland, it's pretty common for all of the older houses to have failing lines and pipe bursting is pretty common, so if they say it would cost more, it may be that they don't have the equipment handy. I just mentioned it because it's come up a few times for me.