How to add a fitting in underground line

[T boy]

I am putting a new bathroom in. I have jackhammed the concrete out to expose the 4" PVC main line. I can get at about 18-20" of it.
I need to add a "T" in this line. There is no movement in the line so when I cut it how do I get a "T" into it.

[Plumber Jim]

You can cut extra off the glue a Wye in with a small piece on the other side of the wye to let it meet the other piece of pipe and use a no hub band.