: : I am about to replace 40 feet of sewerline at my house. My sewer line is 70 feet long. I have cast iron pipe in my line and the last 40 feet has collasped. What do I use to cut that pipe from the good pipe.....A Sawzall?Hacksaw?...what do I connect the new pipe with?How do I connect thy e new pipe to the city?

It is unusual for cast iron to collapse. However we cut it with a metal sawsall blade. Some use 14 teeth per inch other use 18. A special grit blade is available in some areas. A side gringer will cut the pipe. You can rent snap cutters or ratchet cutters from rental stores.
We connect two different kinds of drain pipe with no-hub or fernco couplings. A flexible rubber coupling with stainless steel clamps and sometimes body.
Watch out for cave-ins when you are below 5'. Use solid schedule 40 pipe not foam core or thin wall.
Lonny the Plumber