The failure of £1.5m defences protecting one of the UK’s most flooded villages was down to a faulty sensor, according to an official report.
The main parts of the defences, including a flood barrier, a dam, and two water pumps, were all working properly according to the independent report commissioned by the Environment Agency and released yesterday.
However, the ultrasonic sensor which measured the height of the water malfunctioned because it became “submerged”, the report said. The sensor then gave incorrect information to the water pumps, switching one of them off.
The back-up system which checks that the sensor is working “also failed to operate”, the report by engineering consultancy Arup concluded.
Environment minister Owen Paterson has asked for a copy of the report on the defences at Kempsey in Worcestershire, to establish exactly what went wrong.
Floodwaters inundated 15 homes and about 30 in total were evacuated in the early hours of Sunday, November 25.
The report said an automated dam did work and the water pumps did initially clear water from the village’s flooded brook, but with one pump then switched off, the water backed up and flowed into the village.
The defences were opened earlier this year and were designed to mitigate the effects of a major flood but, in what was the first real test, they failed.
The village has been flooded about 24 times in the last 30 years.
The report says the sensor stopped working properly at 2.46am. Agency officers monitoring the situation from a regional control room some miles away then started to realise something was wrong when the sensor began producing “an erroneous signal”.
Staff were then sent to the site and manually re-started the second pump about three hours after the sensor fault, but by then some homes were being flooded.
The report concluded the defences had successfully protected some homes in the village.
An Environment Agency spokeswoman said: “The pumps are now working and will be manually operated this winter.
“We will ensure the faults are rectified as soon as possible so the pumping station operates automatically as it is designed to.”
Harriett Baldwin, the area’s MP, said the problems identified needed to be “fixed immediately”.
She said: “Now the agency understands the root causes of the flooding, it can identify who is responsible.”