Tuesday's giant water main rupture by UCLA, which ended up spilling 20 million gallons and flooding a huge swath of the campus, put a lot of questions into people's minds about Los Angeles's aging water pipes, but the more pressing question was "Why is it taking so long to shut off the water?" The break occurred at 3:30 pm and the main wasn't officially, completely off until about 9 pm on Wednesday, according to KPCC. What was the hold up? It turns out that "[c]losing aged valves that operate at high pressure is a complex operation," the LADWP says in an official release.
In order to prevent more breaks in the same pipe or elsewhere down the line, 11 other valves had to be adjusted to stop the water flow to the break area. The pipe that caused the destruction at UCLA was 93 years old (from 1921), but that's on the younger side of things; the LA Times says most pipes were installed around 1910. And they're going to keep aging, seeing as the main water lines are only on schedule to be replaced once every 300 years. (As can be expected, there's a complex web of politics behind why they don't get replaced more often; basically, it would cost a lot of money.)
And what about that giant balloon? At one point yesterday, LADWP officials mentioned that they might inflate a human-sized balloon in the pipe to act as a cork to plug the passageway and prevent further water loss. The balloon was not needed ultimately, but before the water could be shut off, there had already been an estimated 20 million gallons of water lost. That's about as much as 100 average families use in a year or four percent of the city's total usage for a usual day, according to LA Observed. Now that the water's stopped shooting all over the place, repairs are underway and are projected to finish late Friday or early Saturday.
Welding work gets underway by our crews on Sunset pipe break as water shutoff operations make significant progress. pic.twitter.com/gfVwVAc7Td— LADWP (@LADWP) July 31, 2014