Don’t fall in: Manhole covers go missing when Miami-Dade streets flood

As streets flood across Miami-Dade County, the mayor’s office had a familiar plea to residents: Leave those manhole covers in place.

“We don’t want flooding getting into the wastewater system and we don’t want wastewater getting into our streets,” Mayor Daniella Levine Cava said in a statement with flooding tips her office sent out Wednesday evening. “So it’s important to keep the manhole covers closed.”

Faced with flooded streets, parking lots and even backyards, people across Miami-Dade sometimes create makeshift, illegal drains by removing county manholes and draining standing water into the county’s sewer system.

Removing the mostly watertight metal discs gives the rainwater a place to go but also can inundate sewage pipes leading to sewer facilities that can only handle so much water.

Miami-Dade’s code prohibits “tampering with utility fixtures,” a civil offense that can bring fines up to $1,000. Loose or missing manhole covers also produce hazards, with the possibility of someone stepping into a pit that can lead to a drop nearly two stories below.

Along with causing a hazard for someone walking by, a missing manhole can wreak havoc with the sewer system it serves. The county’s stormwater system, along with municipal systems inside city limits, is designed to collect rainwater into underground pipes and runoff areas into canals. Those eventually flow into Biscayne Bay and underground aquifers that supply drinking water.

Manhole covers provide access to the sewer system, which can be overwhelmed during floods by the intrusion of rainwater. Too much water flow will overwhelm treatment plants, causing untreated sewage to spill out into the surrounding area and into stormwater drains that will pollute the bay.

During a tropical downpour that hit Miami-Dade in June of 2022, the county’s Water and Sewer Department said it discovered multiple missing manhole covers after the waters receded, including in downtown Miami.

“Our team probably found a dozen that were removed,” Roy Coley, the county’s Water and Sewer director, said. “One open manhole can flood out a whole system. With a dozen of them open, it’s totally flooded.”

This story was originally published June 12, 2024 at 7:07 PM.