City officials say that they've determined the source of pooling water that froze into ice and closed a stretch of 15th Avenue for four days, and they reopened the road Tuesday morning.
A city employee and a private engineering firm examined the trail of water leading down a hill to 15th Avenue on Monday, and determined it came from an underground pocket that built up and surged through a weak point -- like a balloon below the soil that popped.
"All of a sudden, it found a weak point, and it blew through," said Paul Alcantar, the director of the city's garbage disposal utility, which is working to fix the problem.
The water was running down a hill to the north of 15th Avenue, which is the edge of an old city landfill that was used until 1987. The city closd the road between Orca Street and Lake Otis Parkway on Friday, when the water froze into ice.
A geologic survey in 1990 showed that runoff from the landfill had left minor contaminants in nearby wetlands, but Alcantar said that "to our knowledge, there's nothing toxic" in the water on 15th Avenue.
The foul odor and brown color of the water was explained by the fact that it flowed through organic matter called peat, Alcantar said.
The utility did not conduct any testing, but Alcantar said that the engineers had observed a trail left by the water that led down to the road, and it was clear it had come from a layer of soil above the old landfill.
The utility is now preparing to put in a new drain in the slope leading down to 15th Avenue, which Alcantar said should help the water seep back into the ground rather than flow into the street.
Once the weather warms, Alcantar said that the utility would install a longer-term fix: a ditch filled with gravel, channeled to a pump that will remove any overflow.
Throughout Monday, ice from the water only covered a small portion of 15th Avenue's westbound lanes, and the eastbound lanes appeared to be clear.
But Alcantar said that 15th Avenue remained closed as a "precautionary measure."
"With the weather being like it is, you put a little water down there -- it gets a little slick," he said.
Work did not take place over the weekend because "we couldn't get any engineer to come and look at it," said George Vakalis, the municipal manager.
"If we could have fixed it on Friday, we would have fixed it," he said, adding that there were several "workarounds" that residents could used to get around the closed stretch of road.
Reach Nathaniel Herz at email@example.com  or 257-4311.
By NATHANIEL HERZ