The flash flooding that killed four people and forced others to swim to safety or climb onto car roofs was a freak accident caused by heavy rainfall that overwhelmed the sewer system just as rush-hour traffic clogged low-lying city streets, officials said Saturday.
A mother and her two daughters died in Friday's flood after becoming trapped in their vehicle and rising water pinned it to a tree. Another woman's body was washed into the Allegheny River, where she was found Saturday morning.
Back-to-back storms pounded the city with 3 to 4 inches of rain. The water drained rapidly onto Washington Boulevard, a main street near the Allegheny River on the city's east side, with a force too great for a pair of sewer pipes 9 feet in diameter. The torrent blew off 60-pound manhole covers,
"We had geysers here," said Raymond DeMichiei, deputy director of the city Office of Emergency Management. more