That's a lot of fat: A photo showing some of the 15-ton "fatberg" that was clogging up a London sewer system. Thames Water/AP hide caption itoggle caption Thames Water/AP The Two-Way FATBERG! 15-Ton 'Lump Of Lard' Removed From London Sewer August 6, 2013 It's the largest congealed lump of wet wipes and food fat ever found in the city's sewer system. Workers spent about three weeks working to hack it up and haul the pieces away. If they hadn't, raw sewage might have started spurting out of manhole covers.