Crews yesterday completed repairs to a large sinkhole that had Tassajara Road closed in both directions in Dublin since Wednesday night, a city spokeswoman said.
The road reopened at about 5:15 p.m.
The sinkhole was reported on Tassajara Road near the intersection with Silver Ranch Drive, according to Dublin spokeswoman Linda Maurer.
The hole was apparently caused simply by wear on a road that was built long ago, according to Sue Stephenson, community affairs supervisor at
the Dublin San Ramon Services District.
Investigators originally believed the hole had been caused by a broken water main, but that theory was discarded because of the lack of water in the hole, Stephenson said.
"It's an old creek that used to run through there, and it's an old county road," Stephenson said. "The way they made the road back then, things like this can happen when water seeps in from heavy rains and it comes apart."
Authorities placed detour signs south of the sinkhole at the intersection of Tassajara Road and Gleason Drive notifying drivers of the closure, as well as north of the closure in unincorporated San Ramon, where Tassajara Road becomes Camino Tassajara, as repairs were being conducted, Maurer said.
Covering a lane and a half of the north Dublin roadway, workers said the problems leading up to the erosion of earth could have started back when it was first developed. The workers also said it was not something they were previously aware of or watching beforehand.
"We got the call at 10:30 (Wednesday) night," said Dublin police Lt. Kurt von Savoye. "We got the call from CHP so I'm assuming a motorist called it in on a cell phone line."
"We responded and found a big hole and said we'd better close the road," he added. "We called in our personnel responsible for road repairs."
The hole was originally described to the police as 3 feet by 5 feet, and 4 feet deep. But after working on the hole, it was found to be 10 feet by 10 feet, by 10 feet deep, said Assistant City Manager Chris Foss.