AP/Wideworld On Feb. 8, Denver Water employees remove aging, damaged pipe section that broke the day before. Massive sinkhole buckled a large segment of I-25.

A 66-in. water main beneath Interstate 25 in Denver burst on Feb. 7 in the afternoon, creating a sinkhole about three lanes wide and 16 ft deep, shutting down all northbound lanes of the highway.

The cause of the break is still under investigation; however, Denver Water officials said it was likely from a pressure surge in the pipe after a water pump failed. The water built up until the roadway collapsed, creating a sinkhole 40 ft wide by 60 ft long near the 58th Avenue exit ramp in north Denver, according to Stacey Stegman, spokeswoman for the Colorado Dept.of Transportation.

CDOT crews worked through the night to fill the hole and reopen the highway in time for the morning rush hour, but the highway remained close this morning. CDOT hopes to reopen at least one lane on northbound I-25 today, but that would be just a temporary asphalt fix, Stegman said. All the reinforced concrete ripped up by excavators will have to be replaced, and cracks that stretch across two more lanes on the highway will have to be sealed.

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About 150,000 to 200,000 cars drive that stretch of I-25 daily, and CDOT said reopening the roadway is their No.1 priority. Crews from other road projects have been pulled from their jobs so they can help with emergency repairs.

Denver Water expected to have the water main repaired with a new steel pipe today, allowing CDOT crews to move in and complete repairs on the roadway by the Friday evening rush. Approximately 2 million gal. of water leaked from the pipeline the day it ruptured. In comparison, Denver Water’s daily demand at this time of year is 115 million gal., says Stacy Chesney, the water department’s spokeswoman. Installed in 1978, the pipe is one of the major lines providing water to the north end of the city.

The last major sinkhole that affected infrastructure in Colorado occurred in summer 2003 on Interstate 70 near Vail, when heavy rains washed away a large section of the highway. Officials believe that the I-25 sinkhole is double the size of the one in 2003.