Sutton Council worked with the Environment Agency, Thames Water and the emergency services to clear the centre of Wallington following the flash flood there on the afternoon of Tuesday 7 June.

An intense thunderstorm at 2pm saw almost one month’s rain (3.5cm or 1.4 inches) fall across the borough in an hour. An average of 4.9cm (1.9 inches) of rain normally falls during the whole of June.

Around 2m (6ft 5 inches) of floodwater quickly filled up the low-lying area near the railway bridge at Manor Road in Wallington town centre and the drivers of three cars needed to be rescued.

Sutton Council’s highways contractor was quickly on site and began to pump and lower the amount of floodwater on Manor Road. The Metropolitan Police closed part of the A237 and a Local Authority Liaison Officer co-ordinated with the emergency services to remove the vehicles and clear up after the flooding.

As a Lead Local Flood Authority, Sutton Council is responsible for managing flood risk from surface water, groundwater and ordinary watercourses. The Environment Agency is responsible for flood protection from canals and rivers, and Thames Water is responsible for the drains and sewerage system.

Sutton Council employees have been at Manor Road since Tuesday and all the organisations are continuing to monitor the situation. Plans are in place to identify any ongoing flood risk.

Councillor Jill Whitehead, Chair of the Environment and Neighbourhoods Committee at Sutton Council, said:

“We experienced almost one month of rainfall in Sutton in less than an hour on Tuesday. In low-lying areas water can temporarily overwhelm the drainage systems, as occurred in this case. The sheer volume of water overwhelmed the drainage infrastructure and road closures became necessary, as our neighbouring boroughs also experienced. In Wallington we have improved drainage by installing new soakaways that are 8m (26.25 ft) deep to help excess water run away. They have been very effective in preventing flooding over recent years despite heavy rainfall. Unfortunately, it is very difficult to mitigate for the rare occurrence of Tuesday’s deluge due to the sheer volume of water in a very short space of time. We clean the gullies under the bridge every three months. Manor Road was last cleaned less than two months ago on 14 April. The debris found in the gullies had mainly been washed down in the flash flooding. It is very difficult to mitigate for the rare occurrence of yesterday’s deluge due to the sheer volume of water in a very short space of time. We are continuing to monitor the situation as additional rainfall is expected in the coming days. Should that occur and lead to additional flooding in the Wallington area, arrangements are in place to activate emergency services to support our communities.”

Sutton Council uses a gully tanker to suck all the silt and debris out of the gully pot, clear debris from the grill and then flush the system. The gully pot is checked to ensure it is clean and working efficiently. If a blockage is detected, a water jet is used to try to remove the obstruction and get the gully and connecting drain linking it to the Thames Water main sewer running again.

If unable to get the system working, this is noted on the report sheet. Defects are then reported to the Highways Service so its contractor can be instructed to investigate further and make a repair.

This is part of the three-step maintenance process Sutton Council follows.

Step 1 – Regular cleaning of the gully grill by the Street Cleaner team to ensure water can enter the gully pot.

Step 2 – Regular cleaning of gully pots and connecting drains, either quarterly or once every two years, to ensure the system is free from silt and debris and is functioning.

Step 3 – Repair by the Highways contractor where defects are found.

Soakaways are maintained by the Highways Service.

Sutton residents concerned about flood risk should visit the Environment Agency website for updates, sign up for flood warning updates  or call Agency’s floodline on 0845 988 11880845 988 1188.

Street flooding caused by overflowing drains should be reported to Sutton Council using the Report it feature on the council website or by telephone on 020 8770 5000020 8770 5000.