Are Sewer Geysers The New Norm In Chicago? Exploding Manholes Raise Alarm

CHICAGO — After rounds of heavy storms pounded Chicago on Monday, jets of water could be seen bursting into the air from the city’s manhole covers.

Chicagoans reported seeing water gushing from the city’s sewer infrastructure on Randolph Street in the Loop, on Jefferson Street in the West Loop and on Blue Island Avenue in Pilsen, according to videos shared to social media.

The sightings occurred Monday afternoon, when parts of the city saw as many as three inches of rain fall in a short period, leading to widespread flooding and power outages.

The phenomenon — dubbed “urban geysers” for their resemblance to natural spouts like Yellowstone National Park’s Old Faithful, which erupt due to geothermal pressure — has become increasingly common in cities across the country as heavier rainfall due to climate change stresses aging sewer infrastructure.

Susannah Drake, a landscape architect and an instructor at the University of Colorado Denver, said climate change is leading to more powerful downpours over shorter time periods, forcing large volumes of water into the sewer faster than the city’s pipes were designed to handle.

Drake said the intense influx of water creates trapped air pockets and, in turn, pressure differentials, which force that air and water upward through a manhole, lifting its cover and producing a geyser-like eruption. She likened the occurrences to putting your thumb on the hose to make the water spray faster and farther.

“The problem is that you have basically a whole bunch of pipes that are a little bit too small for the rain that’s coming in, and that can cause the rain to then build up in the pipes and shoot out backward through the manholes, rather than having it drain out through the pipes into a sewage treatment plant or into a combined sewer overflow system,” Drake said. “It’s a capacity issue.”

Most sewers in Chicago were built over a century ago and were designed to drain sanitary flow and a limited amount of stormwater directly to the river before wastewater treatment existed, according to the Metropolitan Water Reclamation District.

Today, Chicago’s combined sewer system carries household wastewater and rainwater to Metropolitan Water Reclamation District plants, where it is treated before being released into waterways. During heavy rain, excess flow is diverted through dropshafts into the Tunnel and Reservoir Plan, which was adopted in 1972, where it is stored until treatment plants have capacity.

But even the tunnel and reservoir system — which includes the largest sewer reservoir in the world — has been strained to near capacity levels this summer due to extreme storms.

Drake said cities like Chicago should expect to see urban geysers occur more frequently with heavy storms, unless officials devise strategies for redirecting excess rainwater. She said one solution is to implement green infrastructure to absorb surface water runoff, pointing to Chicago’s “green alleys” as one example.

The “green alleys” act like a sponge and a runway for rainwater, letting some water seep into the ground while the rest gathers into a grooved channel and streams into a manhole that connects to local sewers. Its underground trench system can absorb thousands of gallons of rainwater every hour.

“Part of the challenge is that there aren’t a lot of permeable spaces in cities,” Drake said. “We’ve paved a lot of our cities with roads and sidewalks and buildings and roofs, so the water is forced into the drainage systems, which is how it’s all designed to work. But without these permeable spaces, there’s no flex. There’s nowhere else for the water to go except into the drainage.”

Chicagoans can report urban geysers via the city’s 311 system to request dispatch from the Department of Water Management.