Crews worked this week to repair two large sinkholes in the Los Angeles area.
One of the sinkholes was a 20-foot by 20-foot by 20-foot large gaping hole that shut down the eastbound lanes of Third Street, under the Pomona (60) Freeway
The sinkhole proved to be a lot bigger underground than it appeared from the sidewalk. Soil eroded to leave a cave some 20 feet in diameter.
It was in a precarious place, between the major surface street with the Gold Line light rail and an overpass of the 60 Freeway.
It was the second sinkhole in 24 hours to appear east of downtown LA.
In Alhambra on Tuesday afternoon, heavy equipment pulled away asphalt exposing gaping void below.
Some streets around the sinkhole at Mission Road and Marguerita Avenue remained closed Monday as crews worked to handle the problem.
The first clue Monday had been a small depression in the intersection.
Alhambra Police Sgt. Jerry Johnson said it was not visible till crews broke through the road.
"There was a void of dirt under the asphalt, something to do with the pipes that run under the bridge," he said. "That's the theory and that's what they're exploring."
The bridge crosses a below-grade railroad culvert which had been accumulating soil from an unknown source.
It was possibly being delivered by a siphon pump for runoff that malfunctioned, officials said.
After raising concerns in both locations about whether the loss of soil may have cause structural problems, engineers concluded support for the freeway, rail line, and Third Street were not compromised.
