Have you looked at your contract with him? Is he insured? The breakage issues might be on him and his policy.
We thought about that, but we don't know how to show that he broke the pipe rather than that it was just already broken.
Then perhaps what can be done is to just replace the currently broken stretch with PVC.
Well, that "just" is what's $4,000 -- and then we still don't know what's between there and the street (and if more is broken, that's what pushes it up to $15,000).
I just asked E.G. for more details on the broken pipe -- is it that whole section, or just one section at the end? why did the roots gather where they are? -- but he'll be in a meeting 'til noon, so won't get answers 'til then. (I didn't actually see any of this, all my info is from him.)