The upside of 10 days’ worth of rain falling within eight hours is that Guernsey’s water reserves are now full!
Guernsey Water confirmed the benefit after outlining exactly how much rain fell on Wednesday and how it impacted the systems across the island.
The Met Office said 33.3mm of rain fell on Wednesday, which Guernsey Water has likened to “10 days’ worth of rain fall in eight hours”.
That “placed intolerable strain on drainage systems” said the utility with staff tasked with keeping the foul and surface water systems operating at full capacity as flooded areas started to be reported across the island.
This led to eight million litres of water being collected in the storm tanks at Belle Greve Wastewater Centre, and 25 million litres of water being collected from a single stream.
That is more than twice the daily average, and roughly two day’s worth of water supply for the entire island, said Guernsey Water.
There was an immediate safety risk during the heavy rainfall, with foul water breaching the surface as drains were overwhelmed.
12 manhole covers had to be reset after being lifted in the floods with people urged to stay out of the water to avoid any risks.
“When storms like this hit, our primary focus is to keep the foul and surface water systems operating at full capacity to try to clear as much stormwater as quickly as possible,” said Guernsey Water.
“Our teams were immediately deployed to deal with potential blockages, re-setting manhole covers and clearing debris from screens.
“Teams were busy at surface water pumping stations ensuring the screens into them remained clear of debris – allowing us to drain water from the system as quickly as possible and ensuring all pumps were running at full capacity. This is the greatest contribution we can make to mitigating flooding on such a wide scale.”
Guernsey Water received nearly 100 phone calls on Wednesday as customers reported issues, with 61 emergency cesspit collections later on in the day and on Thursday.
The utility said its staff “worked with partner agencies to assist wherever possible”.
“All in all this was a real team effort from people across the company to do whatever we could to mitigate the effects of the heavy and prolonged rainfall.”