Baltimore DPW Reports Sanitary Overflow Due to a “Fatberg”

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Turns out Baltimore has its own fatberg in its sewer systems – a congealed lump of fat, along with wet wipes and other items that do not break down in sewer systems.

A massive plug of grease has been growing, far below the surface, in a midtown sewer main between Baltimore Penn Station and the 1700 block of Charles Street, which includes the Charles Theater. This caused a dry-weather sewer overflow on Sept. 21 which discharged nearly 1.2 million gallons into the Jones Falls at North Charles and West Lanvale Streets. It was the second time in as many weeks that the fatberg created a sewer overflow.

Overflows of the sanitary sewer in that area have become woefully common following heavy rains. Engineers for the Baltimore City Department of Public Works (DPW) decided to explore the sewer in that area to determine the cause of the recent dry-weather overflows.

They sent a machine with a closed-circuit television camera into the sewer, and soon discovered the walls of the sewer pipe were caked with congealed fats, oils, and grease (FOG). Unfortunately, as they were working in the pipe a backup occurred and led to a sewer overflow.

The buildup of FOG inside the pipe was so thick that it slowed sewer water moving through that area. Engineers estimate that 85 percent of the pipe, which is 24 inches across and more than 100 years old, was blocked. This resulted in sanitary sewer overflows happening underground, in a structured overflow that was designed more than 100 years ago as a sort of pressure-release valve in the event the sewers backed up.

The overflow is diverted into the stormwater system and then into the Jones Falls. The structured overflow, in the 1700 block of Charles Street, and a handful of others like it will be closed once a project to eliminate a restriction at the Back River Wastewater Treatment Plant is completed in late 2020.

The City’s sewers are being repaired and replaced to avoid infiltration of stormwater.  This work will be done as the capacity of Baltimore’s sewer collection and treatment systems are upgraded under the City’s sewer system consent decree. Any repairs or replacement of the sewer pipe that crosses Charles Street at Lanvale Street will be determined once the FOG has been entirely removed.

DPW has a FOG program in effect which includes monitoring of food service establishments that discharge, or have the potential to discharge FOG-laden wastewater.  These establishments must have a valid wastewater discharge permit and have functioning grease control devices, among other requirements, in order to be in compliance with the FOG program.

Can the Grease, Trash the Wipes

Private residences are not subject to the same regulations as food service establishments but should still take steps to keep fats, oils and grease and non-flushable items out of the sewer system and prevent costly overflows.  Here are a few simple tips to remember: 

  • Do not put FOG down the drain.

  • During food preparation and cleanup, pour unused grease from the “pan to the can.” Once it solidifies in an empty can, put it in the trash.

  • Do not flush “flushable” wipes; put them in the trash instead. Wet wipes don’t break down in water and create sewer blockages.

  • The only items that should be considered flushable are poo, pee, and toilet paper.

For additional information and other tips on protecting your pipes, visit

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