"PG&E wants to remove all the trees that shade his yard and seven other households because they are over major gas lines 132 and 109, and could damage the line and cause an explosion."

I'm sorry, but this makes sense. That _is_ the reality of the situation; a situation that must be rectified. It stinks that the 8 property owners are being blindsided, but I'm sure restitution can be made. I think the safety of the general public is worth a little shade.
Sometimes there's no solution where everyone can win, but I prefer my gas lines un-ruptured from invasive roots. Ever see what even small roots can do to a sewer line? Lets do what we demand PG&E does: Make public safetey Priority #1

You think this is bad, wait until HSR comes to town.

If the trees are removed and new pipe put in...
What happens then?
Will the home owners be allowed plant new trees over the same spot or will they told they can't plant trees because they have a gas line in that spot?

It would annoy me if I couldn't have trees to shade my home from the hot sun.

I would think re-routing the gas line would make it safer for the homes 30+ years in the future... especially if planting new trees in the same location above the gas line again.

Something is going on here. Either these people don't read the papers they sign when they buy these homes.. or PG&E doesn't actually have an easement.

If you buy a place and don't read all the paperwork.. that's your fault. I own a home with a PG&E easement along the back of the yard for the power lines. It was there when I bought it.. it was up to me to accept it or not.

Now if PG&E doesn't have an easement them tell them to go pound sand. Somehow I don't think PG&E would be so stupid though.

Otto - Does your PGE easement specifically say they can come and rip up every tree and shrub from your backyard?