Massive Sewer Clog in Baltimore Removed

A dry-weather sewer overflow happened in Baltimore on September 21st . Nearly 1.2 million gallons of raw sewage flowed into Jones Falls. The cause of this overflow was a massive plug of grease, “flushable” wipes, disposable diapers and other things flushed down the toilets in the city. The Department of Public Works in Baltimore called the 20 foot clog a “fatberg” after the 130 ton clog of fat that was found clogging the London sewer system earlier in September. Last week the  Baltimore Department of Public Works managed to remove fatberg sucking it out of the sewer using their pipe cleaning equipment. The cost of removal was estimated to be $60,000.

Overflows of the sanitary sewer in that area of Baltimore had become more and more 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 or FOG as its called in the waste industry.

The buildup of FOG inside the pipe was so thick that it slowed sewer water moving through that area. Engineers estimate that 85% of the pipe, which is 24 inches across and more than 100 years old, was blocked. This resulted in sanitary sewer overflows into the stormwater system to prevent backed up sewage from surfacing on the streets.

Instead, the overflow is diverted into the stormwater system and onto the Jones Falls. The city hopes to eliminate a handful of points that divert sewage to the stormwater system when an expansion of the Back River Wastewater Treatment Plant is completed in late 2020. This work is being done under the City’s sewer system consent decree.

FOG comes primarily from food such as cooking oil, lard, shortening, meat fats, sauces, gravy, mayonnaise, butter, ice cream and soups. Sinks, dishwashers, cleaning wastewaters and food scraps put down disposals deliver the FOG to the sewer system, it can be liquid or solid when you put it down the drain, but turns viscous or solid as it cools in the miles of underground sewer pipes. As the FOG builds up with other debris flushed down the toilets, it restricts the flow in the pipe and can cause sewage to back up into homes and businesses, premature failure of the sewer pipes, increased incidence of sinkholes, or in combined systems like Baltimore, Alexandria and Washington DC sewage released to the stormwater system.

FOG only really creates problems for the sewer lines if there is a disruption, like a tree root in a joint, or sag under a highway, a pumping station or something that might give the FOG a chance to catch on the pipe surface and cling to the walls of the sewer system. Since all pipes have some friction points, FOG is always a problem. The FOG builds up one layer at a time making a smaller, narrower path for the water and waste to travel through, ultimately causing a backup or pipe to burst. Time creates wear and tear on a pipe and without aggressive maintenance and with the addition of wipes and other debris the problem grows to unbelievable proportions.

Restaurants and commercial kitchens are required to have grease traps between the sink and floor drains and the sewer connection and capture and recycle their grease, by having it hauled away. 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. If you want to see what fatberg looked like see the video.  Here are a few simple tips to remember whether you are on public sewer or have a septic system:

• 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.