In a reminder of the danger of sewer systems a boy fell into a live main through an abandoned facility in LA this week.  Miraculously he was found unharmed hours later after an exhaustive search effort.  The big break was noticing hand prints on the interior of the main while using CCTV equipment to assist in the search.  A link to the ABC article is included below.

http://abcnews.go.com/US/authorities-search-boy-fell-drainage-pipe-los-angeles/story?id=54170554