Work went on day and night after that sinkhole began to open at Alvarado Boulevard and New Haven Street last Wednesday.
It grew to a size of 35 feet by 40 feet.
Crews also needed to replace utility lines before they filled the hole.
Officials don't know what caused the sinkhole to develop.
If you see news where you live, tag your photos and videos on Twitter, Instagram, or Facebook with #abc7now.
Laborious work digging to repair broken water main. #UnionCity sinkhole now 10' deep. Sewer line at 15'. #abc7now pic.twitter.com/XETstfZJzE
— David Louie (@abc7david) October 15, 2015
#HappeningNow in #UnionCity. Sinkhole grew from 6x6 feet to 25x25 & 10 feet deep. Latest on work & traffic at 11am. pic.twitter.com/npIMLy3BnH
— Matt Keller (@MattKellerABC7) October 15, 2015
Union City sinkhole filling with water, Alvarado Boulevard & New Haven St. #abc7now pic.twitter.com/jPEliuVsVn
— Cbarnard (@CornellBarnard) October 15, 2015
Update: Sink hole on Alvarado Blvd is roughly 10ft x 12ft. Depth unknown. Area remains blocked off to traffic. pic.twitter.com/HZlIObRUbv
— City of Union City (@UnionCity_Gov) October 14, 2015
sinkhole in front of AMS...the world is ending yo pic.twitter.com/2b5SZcdDhV
— C J (@christinegolfo) October 14, 2015
Huge sinkhole near my old elementary school in Union City. NBD right? pic.twitter.com/tnjTwo7I2M
— Marjan Rajabi (@_mar920) October 14, 2015
Northbound lanes on Alvarado Blvd are closed btwn Fair Ranch Rd & Fredi St until further notice due to a sink hole. PW crews are on scene.
— City of Union City (@UnionCity_Gov) October 14, 2015
Correction:Westbound lane on Alvarado Blvd is closed btwn Fair Ranch Rd & New Haven St until further notice.Crews are monitoring a sink hole
— City of Union City (@UnionCity_Gov) October 14, 2015
