Omaha’s Pacific Street sinkhole that swallowed two vehicles in February became an internet sensation, but the city’s day-to-day experience with underground collapses is broader than the viral clip suggests. City officials and geologists tied the risk to local soil conditions and the way water can move sediment beneath roadways—factors that can lead to cave-ins ranging from small pavement dips to large voids.
City Engineer Austin Rowser said the city has logged more than 2,100 cave-ins over the last five years, from minor depressions in pavement and sidewalks to large chasms like the one that opened on Pacific Street. Rowser said many cave-ins never rise beyond a localized surface issue, but they still require follow-up because officials must check the underlying cause to prevent additional sinkholes.
The Pacific Street collapse began as a deeper infrastructure problem, Rowser said, describing a sequence that started months earlier with a small leak in a Metropolitan Utilities District water main. He said the water leak found its way into the storm sewer, creating a small void that went undetected, and that the moving water eventually pushed enough dirt into the sewer to form a large cavity that later collapsed under the weight of two vehicles on Feb. 24.
Retired geology professor Harmon Maher described how he first noticed something wrong before the road failure. He said that while walking near the Keystone Trail in central Omaha in February, the creek next to the path—normally gray-green—ran bright orange, suggesting sediment was washing into the water from upstream construction. Hours later, his son alerted him to the Pacific Street mishap that was quickly becoming widely shared.
Videos of the road collapse helped drive the story worldwide, but geologists said Omaha’s sinkholes tend not to match the textbook pattern associated with naturally dissolving bedrock. Matt Joeckel, Nebraska’s state geologist and a University of Nebraska-Lincoln professor, said the state is one of only a few that does not appear to have much karst topography, the type of dissolvable bedrock that can make large sinkholes possible. He said Omaha’s sinkholes are generally shallower and often result from human-made infrastructure interacting with loess, a fine-grained sediment that is vulnerable to being carried by water.
City Engineer Rowser said loess—useful for growing corn—creates a challenge for building roads because it can be transported away when water finds pathways underground. He also said Omaha’s hilly topography can aid that movement, and he noted that seasonal differences matter: the city sees far more cave-ins in warmer months because frozen soil erodes less easily.
Officials said many cave-ins appear only as slight dips, and not every event looks dramatic at the surface. Rowser said the city ordered barricades for about 40% of cave-ins that indicated some kind of hazard where they occurred. He said the city’s approach centers on investigating every report to identify the root cause, rather than assuming that only major collapses pose a threat.
The investigation process, Rowser said, often begins at the scene. He said city employees typically introduce dye into a hole or crack in the pavement, then look for it downstream in the sewer water; seeing the dye helps confirm that water and sediment are leaking into the sewer. Workers can then trace where the leak enters and repair the sewer to stop the underlying problem, while cases where dye does not show up may point investigators toward other causes such as an animal burrow or dead tree roots, which they can fill with special concrete.
Not all accounts of the Pacific Street collapse have aligned. The Metropolitan Utilities District and Omaha have been locked in what Rowser described as a chicken-and-egg dispute, with MUD challenging the city’s explanation and contending that the damaged storm sewer was responsible for the sinkhole and that the water main break came after the road collapse. Both the city and MUD have filed claims against each other for repair costs.
Joeckel and other local experts said the risk is not limited to one dramatic incident. They said that while the chance of injury from a sinkhole is low, engineers still need to account for the reality that the ground beneath roads can erode rapidly when conditions allow water to move loess or fill dirt underground. Ashlee Dere, a University of Nebraska at Omaha geology professor, said it is “surprising” Omaha’s sinkholes do not cause more problems, given the soil type, human-altered topography and aging infrastructure.
In Omaha, Public Works crews have seen reported cave-ins decrease from more than 500 in 2021 to about 340 last year, Rowser said, while geologists warned that the underlying risk can rise as underground systems age. Rowser said the city has also explored new ways to diagnose issues underground in recent weeks, including considering fiber optic cables to detect leaks in water lines and alert the city earlier. Joeckel said conducting certain geological surveys could help identify where water is concentrated and potential trouble spots, adding that it would be better “if you could see what was going on below the surface before something happened.”
After the Pacific Street collapse, crews repaired pipes and filled the missing road section, and the street reopened to drivers nine days after it closed. Rowser said the sinkhole’s internet fame was amplified by a University of Nebraska at Omaha security camera recording the moment, and he said the video’s popularity reflects how people are drawn to unexpected events. Harmon Maher said he suspected that viewers were intrigued by the sudden realization that “the ground that is so solid and firm beneath your feet just gives way.”