More sod

Since most of the grass is dormant and spring seems to be edging its way into the air, I decided to make another run at cleaning up the front yard and digging just a big more. To my surprise, underneath the area that I had heavily poisoned, that nasty Bermuda grass or grass of evil, has roots that are alive and well. A good 3-4 inches under the ground is a network of roots like an alien life form...I can't believe they didn't die. What will take to get rid of this stuff? In my whacking and hacking frenzy, I discovered some more buried pavers that I placed on my completed pathway. At least I am assured that the work will never be done and I will never be completely bored.