Tracking the roots ofdeluge in Kirkby Stephen
AN unnamed watercourse in Kirkby Stephen helped contribute towards the flooding in the town during December, a new report has found.
The watercourse starts in an area known as Bengy Hill, close to the railway station and not far from Waitby Common.
Sixteen recommendations have now been made in the report, which aims to minimise the risk of future flooding in Kirkby Stephen.
It shows that nearly 40 properties in five different parts of the town were hit by Storm Desmond between 4th and 6th of December last year.
These included Quarry Close, Birkbeck Gardens, Station Yard and South Road, as well as High Street, North Road and Hartley Road, plus the Mill Lane area and the Hartley Low Mill area, the latter of which was largely confined to flooding on the highway.
The flooding in Quarry Close and Birkbeck Gardens saw the fire service called out at 5-22am.
The flood report finds that the incidents across the town were caused by water from a combination of sources including the River Eden, ordinary watercourses, surface water, drainage systems and ground water.
The report identified that Kirkby Stephen has three significant watercourses which are the River Eden, Croglam Beck and, crucially, an unnamed watercourse near the railway station.
It flows openly down towards Station Yard before slipping under a culverted tunnel section under the A685 and then continues flowing to meet the River Eden at High Stenkrith Bridge.
The unnamed watercourse flows parallel to the A685 before entering the culvert to pass under the road. The culvert is approximately one metre in diameter and after passing under the A685, it flows along the rear of Pennine View Caravan Park.
Once it gets through the caravan park it then flows towards the recently-built Quarry Close and Birkbeck Gardens.
Attempts to survey inside the culvert have not been successful because the construction of it makes it difficult for the equipment needed to get through.
The report found: “As the flood flows left the caravan park and flowed into Quarry Close, the flood water overwhelmed both the highway drainage and public sewer systems. During interviews with residents of Quarry Close, it was commented that the road drains were unable to accommodate the volume of water that flowed into the area.”
The report added: “Highway drainage systems are designed to collect rainfall that falls on to a specific area of the highway and are not designed to collect run-off from other areas. This would be evident during the event on 5th December, 2015, when the gullies were overwhelmed by the volume of water from the unnamed watercourse, which they are not designed to collect.”
Story Homes, the developer responsible for Birkbeck Gardens, had installed a drainage system after previous flood water had overwhelmed the site, but the county council was told that they were not aware of the extensive amount of flood water that had been coming from the unnamed watercourse.
The report said the developer is working with Cumbria County Council to establish a way to resolve the situation.
In previous floods, large branches in the culvert underneath the A685 had been removed.
A number of recommendations have now been made, not least a full assessment of the catchment and the capacity of the unnamed watercourse culvert.
There will also be investigations into how to manage the unnamed watercourse upstream of Kirkby Stephen and to identify possible options to prevent it flowing through the caravan park and towards Quarry Close and Birkbeck Gardens.
The recommendations include actions for flood risk management authorities as well as landowners, residents and businesses.