The Baltimore City Department of Public Works said workers on Wednesday discovered a sinkhole on the property of the Montebello I Water Treatment Plant and are working with state and local partners to stabilize the site, secure the pipes and maintain water service.

DPW Director Jason Mitchell said in a statement Thursday that a compromised 108-inch storm water main installed in the 1880s — which does not supply drinking water — caused the sinkhole. That has exposed an 84-inch water main.

In an update late Thursday night, Mitchell said DPW decided to take the 84-inch main offline “out of an abundance of caution and to ensure the safety of those working at the location.”

Water will be diverted to a smaller 48-inch line, which could lead to decreased water pressure in some households and businesses, he said.

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Operations at the treatment plant have not been affected, said department spokesperson James Bentley.

The sinkhole is located just north of Lake Montebello, but the broken main is not connected to the filtration system and is not near any machinery used in the water treatment process, he said.

City Councilwoman Odette Ramos, whose district includes the filtration plant, said the 48-inch pipe is the same one that was shut down earlier this year when a sinkhole closed part of North Avenue in East Baltimore.

The line has been flushed and tested several times and is “clear to hold our drinking water” until the larger one near the Montebello I Water Treatment Plant is restored, she said.

Ramos told residents in an earlier email the faulty pipe near the plant was discovered several months ago as city workers investigated the cause of persistent flooding at 35th Street and Hillen Road.

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The broken pipe caused the ground around it to become unstable, she said.

Pedestrian access in the area, including paths around Lake Montebello, may be limited, she said.

In an email, Jay Apperson, a spokesperson for the Maryland Department of the Environment, said DPW reached out to the state after discovering the sinkhole.

The agency will continue to provide regulatory oversight to the city’s response, he said.

Up to 128 million gallons of water are treated at the Montebello I Water Treatment Plant every day, according to DPW’s website.

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In the 20th century, Baltimore implemented disinfection methods and became a leader in clean drinking water.

Today, the average age of water mains in Baltimore is 75 years old. Many are more than 100 years old.

At a hearing, officials cited a series of failures stemming from the city’s aging infrastructure as the likely cause of an E. coli contamination that led to a boil water advisory in September in parts of West Baltimore and Baltimore County.

Additional reporting by Brandon Weigel

dylan.segelbaum@thebaltimorebanner.com