Fatberg causing overflows
Recent sewage overflows and blockages are a timely reminder to be careful what you put down the sink and toilet – it could contribute to a fatberg that will eventually play havoc on the city sewerage system.
The term fatberg describes congealed lumps found in sewer systems, formed by the combination of non-biodegradable solid matter such as wet wipes, with grease or fat.
Fat and grease that enters the system will eventually build up on the base flow level of sewer pipes and continue to expand until it reaches a level where it causes a blockage.
“We use CCTV camera footage to identify the cause of blockages in our network and this is how we sometimes find fatbergs,” says team leader of storm and wastewater, Wolfgang Kanz.
“Because these fatbergs are difficult to get to and remove, we jet-clean the pipes, which in simple terms is using high pressure hose to dislodge the fatberg, allowing it to be sucked out down the pipe.”
Routine maintenance will dislodge small fatbergs but sometimes they build up in size and put significant pressure on the sewage network.
After the last heavy rainfall event that resulted in opening the emergency discharge valves into the river, contractors discovered a large fatberg that likely contributed to the overflows.
People can help prevent this from happening by ensuring fat, oil, grease and other non-flushable items do not go down sinks and toilets. The non-flushable items stick to the fat and help the fatberg get bigger.
Oils and fats should be wiped out of pans and disposed of in the rubbish.
Although some wipes are labelled as flushable, they are not biodegradable and should not enter the sewer system. Wet wipes down the toilet are one of the biggest causes of blockages at the expense of ratepayers.
Cities all around the world are facing increased pressure on their sewage networks due to fatbergs. Last year a 250 metre long, 130 tonne mass dubbed the ‘Whitechapel fatberg’ was found in London’s underground sewer system.