20 million gallons of potable water later, the massive double "trunk line" break that's resulted in spectacular flooding in the streets of Los Angeles and throughout the UCLA campus has finally been sealed off and crews have this bulbous blockage to thank for it.

The water main break, which began Tuesday afternoon along Sunset Boulevard involved the rupture of not one but two high pressure 30 inch-diameter "trunk lines"—the plumbing version of an electricity company's high power transmission lines—right at their junction point. The LADWP first attempted to cut off water to the rupter through conventional upstream valves, however they immediately ran into issues. According to the LADWP:

Water flow into the work area has slowed as LADWP water crews carefully work valves in the area to fully close off water to the site of the rupture. Valves are located near the break and along the two trunklines that connect at the point of a "Y" juncture where the break occurred, and connect to Stone Canyon Reservoir. Closing aged valves that operate at high pressure is a complex operation to ensure additional breaks on the lines do not occur.

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When the valves proved ineffective at stopping the leak, LADWP crews turned to a more direct method. They dug down to the rupture and inflated a "balloon" similar to what NYC is developing to halt chemical attacks and flooding in its subway tunnels, which temporarily stopped the flow of water, giving crews a chance to engage the valves and begin patching the ruptured pipe. Up next: draining the flooded UCLA parking garages and beginning damage assessments, which some estimates already put in the hundreds of thousands of dollars. [LA Weekly]

Image: LADWP

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