I provide below an update into how Southern Water is responding to sewer flooding in catchments affected in Sir George’s constituencies, but before I do so it might be helpful to explain what we are responsible for when flooding occurs.
Southern Water, of course, is not the authority responsible for groundwater, river water or surface water flooding. Our responsibility is to ensure, as far as is possible during exceptional conditions, that wastewater services are maintained for our customers – and we are presently spending £100,000 a day to achieve just this.
Our sewers have become inundated with groundwater following the wettest winter since records began. To protect toilet and bathroom facilities for our customers we employ huge tankers to suck the groundwater from the sewers and transfer it to local wastewater treatment works. We also install overpumps to pump from the sewers into local watercourses. Pumps are 30 times more effective than tankers but obviously their use is a temporary, emergency measure as we do want want to pump wastewater, albeit heavily diluted with groundwater, into water courses. We work closely with the Environment Agency to ensure the impact of this is minimised.
As you know, we also keep stakeholders and customers updated on our work. Now, as promised I can provide the flowing snapshot of what we are doing to help in the following villages which are in Sir George’s constituency:
In King’s Sombourne we are consulting with the Environment Agency regarding the potential introduction of overpumping from the pumping station along the bed of a stream .Once levels drop, we shall sandbag manholes to help prevent further inundation.
In Mullens Pond we are overpumping from the pumping station straight into the bourne behind it. We have also upgraded the pumps at the station to bring about a 33% improvement in performance. This has allowed us to stand down the tanker in Mullens Pond and this has also reduced the groundwater levels in our sewers in the nearby parish of Thruxton.
The flooding situation is quite bad in Vernham Dean but Southern Water does not have any sewers in this village.
Also particularly severe in Hurstbourne Tarrant but this is generally ground and river water. As outlined above, we are not the responsible authority but we all work together to do what we can to help residents. Our priority, of course, is to try to maintain wastewater services to our customers. We have three customers who no longer can use their toilets and bathrooms in the village. Flooding has forced two of them out of their properties and, in honesty, when the water levels are this high, the sewers fill again instantly with the floodwater above them, making this a futile operation. It’s like trying to empty a swimming pool with a teaspoon and there is little that can be achieved by a water company until sewer levels drop.
However, in Appleshaw, although parts have been under a foot or more of water, the situation is more manageable. Last night we commissioned an overpump in Appleshaw Road - and almost immediately the sewer levels began to recede, as did the flooding of the road to a point where the highway flooding has virtually disappeared. There is a long run of pipework (several hundred metres) from the pump to the watercourse which avoids an earlier alternative of pumping wastewater onto to a nearby field - but some delay was caused by needing to clear the privately owned ditches and stream. Nevertheless, Southern Water conducted
The initial result is pleasing. In view of this, one of the two tankers in the village, transferring wastewater from the sewers to a local pumping station, has now been stood down. However, the second tanker will be retained while we review the longer term performance of the overpump which should afford more security to Appleshaw's sewers which have been inundated during the wettest winter since records began.
Similarly, the use of overpumps in St Mary Bourne, Ibthorpe and, more recently, Stoke have greatly improved the situation in that part of Hampshire where manholes are no longer overflowing.. I have written separately to Sir George at the times we commissioned each of these pumps so he is aware of what we are doing here.
Finally, in Penton Mewsey we are using an overpump to transfer wastewater from the sewers in the centre of the village into the river – although it is subject to some treatment and is heavily diluted by groundwater. However, the sewers are struggling in the village and we are discussing with the Environment Agency the possible installation of a second pump but, obviously, we need to comply with environmental requirements.