and openings in it. we try to stop, not only infiltration, but exfiltration, where sewage would actually leak out of the pipe. the head is larger, so it breaks away the old pipe and allows the new pipe to come in behind it. griffin: we are saving about 67% of the cost of actually digging old pipe up. clyne: it's less invasive than an open-cut process, where you would open the whole trench up and replace the pipe. it's called "trenchless" technology, so... that's as good as it gets. griffin: we don't have to dig up everyone's yard, and we refurbish that pipe at a much-reduced cost. another technique, the cured-in-place lining. it's equivalent to putting a large sock through the existing sewer. we form a new pipe inside the old pipe, and therefore we seal up all of the defects that allow rainwater to come in. hunter: we repair