A 120 tonne fatberg, equivalent in size of a blue whale, has been removed from a large trunk sewer in Oxford. Clearing the fatberg required a coordinated effort from multiple Thames Water teams and contractors, highlighting the scale and complexity of the operation.

Photo: workers entering large trunk sewer

Every year Thames Water clears 75,000 blockages from their sewer network, at a cost of £18 million. This year to date Thames Water has cleared 35,178 blockages including:

• 23,556 wet wipe related blockages
• 11,104 fat, oil and grease blockages
• 518 3rd party blockages, such as concrete and other items

Multiple teams joined forces to tackle the 120-tonne fatberg, stretching over one kilometre through an Oxford trunk sewer. The complex operation took two weeks to complete, involving the removal of congealed fat, oil, grease, and wipes from the pipe located 20 metres underground.

Due to the pipe’s size and depth underground, high gas levels elevated by the fatberg, and the need to maintain Oxford’s wastewater flow, the operation required careful planning with safety as a top priority. This included securing special permits, safely venting the built-up gases before entry and taking advantage of the dry weather conditions to ensure a safe and controlled operation.