Most PVC pipe that size I've seen is sealed & heeled together by a rubber gasket built into the female end. (you grease it before slipping it on & seating it in place with the help of 2x4 or sledge hammer) You can drill some screws though the sides that overlap then back them out half way & coat with a good silcone clauk then rescrew back in to seal them. Hope this make sense & helps.