Hey BP, I have a up-down duplex in Provo, Utah. The basement tenants heard gurgling in the toilet when the washing machine was running upstairs. 

Initially thought it was a vent blockage, but we had a camera run through the lines, and there is a 3 foot section of the main sewer line (cast iron) with trench rot. A little further down, there's a section with substantial root penetration. Also some of the pipe joints are starting to get misaligned. 

Plumber recommended putting a resin-liner in. Quoted $7,000 for 40 feet. The pipe is about 2 feet down, and will require a few feet of excavating cement where they will put in the liner and a new cleanout access point. About 15' of the 40' is under concrete, and the rest under the front lawn (won't need to be excavated if we do the liner method).

Does 7k for 40' seem reasonable? 

Anyone know if pipe bursting is an option in Utah County? Wouldn't be opposed to digging the whole thing out and replacing it at the right price either.

Duplex is occupied as well. 

Thanks!