After ever increasing visits from "Greg the Drainman," who's been griding out roots from the 8' of waste line closest to our house, we agreed we'd go ahead and REPLACE that section of old line. We replaced the majority of the waste line a couple years ago, before Davey was born, but we opted to not replace the section that ran underneath the paver patio and flower beds.
Check out this big patch that Mark found when he dug out the line. Once he cut through the top of the waste pipe with the Sawzall, under the patch he found this huuuuuge mat of roots. In fact, he didn't dare get rid of all the roots as it looked like there would be no pipe left. Instead he just cut a path through it so we can at least use water in the house while we wait for the plumber to replace the line.