Some metal content...I need to possibly replace a 40+ year old galvanized pipe from well house to house about 20 feet away. The pressure drop in the pipe while under flow has gradually been increasing over the last few years, due to restrictions from rust and mineral deposits. The line is buried 36" to 48" deep, and I believe it is a straight run, (I did not put it in). Unfortunatly in the many years since it was buried, a hickory and a pine 12" to 15" diameter have grown up near the line. I have a backhoe, but I'm sure digging it up would probably harm the tree roots, and I would rather not have to cut them down. I'd like to replace the old galvanized line with a new line of galvanized steel or copper, but instead of 3/4" diam, something like 1 1/4" for minimal pressure drop to the house, (we do a lot of plant watering). Thoughts on non invasive methods of replacing the line are needed! Some ideas I had - maybe not good ones are the following:
Pipe dream 1.) Take 2" pipe which I have on hand, and fit one end with a hollow cutter like a rota-broach. This would then be pushed over the existing 3/4" pipe, while rotating it with a portable pipe threading head, which I could borrow. I would also be feeding water in the open end of the pipe via a rotary coupling to help flush the "tool". Hopefully the tool would follow the existing straight pipe run to the well house 20 feet away, and I could simply use the 2" pipe as a chase for the new 1 1/4" water line.
Pipe dream 2.) Pull the old pipe with a hydraulic puller into the house's walk in basement, while using the well house end of the old pipe to pull in the new pipe. Plastic line could be used, but I like the additional grounding of a metallic line, ( I have a 8' grounding rod at the main service entrance and at the shop sub panel), as I do a bit of TIG welding w/HF and I also think it helps with lightning protection to have as much grounding area as possible. Pulling may not work if there is a union underground which is a distinct possibility.
Pipe dream 3.) make a water lance from 1/2" steel pipe, connect it to a hose from the water outlet in the well house and use it to washout a enough of a channel below the existing pipe to help free it up.
Pipe dream 4.) Try and rod out the existing 3/4" 40 year old water line.
Or lastly, call a company that does water jet or Hydraulic pipe installation under roadways, drives etc. Not sure what the cost on this would be...I do have garage door access to the basement end of the pipe for a reasonably sized machine if needed, but would need to move some equipment out of the way.