The customer has an S shaped drive made out of pavers. The drive goes from his main concrete drive across the front yard and consists of two 3' wide rows separated by 3' strip of grass. We got to cross under them several times. I know I can tunnel under and put in a 2" sleeve. When I back fill around my sleeve do you think it will be enough to just flood sand back into the tunnel? Or am I going to have to force concrete back in the tunnel. Keep in mind he may drive a car across this some day. The pavers are cemented in on the edges and sand filled in center. NO way around this.