Do I need a Real Estate Attorney? Do I have a case?

The township (Ross Twp, PA) in which I live owns an alley-way/right-of-way next to my property, and on it is a large tree. The tree's roots worked their way into my sewer line, backing it up and causing me to pay a $1600.00 plumbing bill to dig up the line and clear it. I have everything well-documented with pictures and plumber's receipts. I have tried to contact the Township to have them reimburse me, but they won't return my call. Do I have a case against them?