Southern Water - Groundwater / winter readiness update in Alkham

As the weather turns and head into the colder and wetter winter months, I absolutely recognise that some communities across Kent will be concerned about rising groundwater levels. Therefore, I wanted to share an update with you on the work we’ve been doing to ensure we are as prepared as we can be for the winter.

Why did our sewer network struggle to cope during groundwater season last winter?

During periods of heavy rain, local drains and sewers can become inundated with surface water run-off, which puts significant pressure on sewer network and local Wastewater Pumping Stations (WPS). Last winter we experienced extreme levels of rain, which meant groundwater found its way into the sewer and contributed to an elevated water table.

Areas in Kent that particularly suffered from groundwater infiltration were Copperfields, Lydd, Newington and Peene, Folkestone and Alkham, Dover.

Preparing for this winter

Our preparation for this winter during last winter’s groundwater season in April 2024.

Sessions were held with teams across Southern Water, using insight and lessons learnt to ensure we could improve our response this year.

One of the key activities in the early part of our preparation was to create a series of ‘Playbook’ scenarios across our most significant groundwater catchments. By creating playbooks, we’ve ensured are teams are prepared for a variety of groundwater scenarios to ensure our operations team can react quickly, if necessary.

Improving our response this winter

A number of changes have been made to our response this winter, from both an operational and a communications perspective:

Operational improvements

Enhanced use of our Sewer Level Monitors (SLMs), which ensures we can monitor our catchments live, so we can react quickly if we see groundwater levels rising.

Several Wastewater Pumping Station winter readiness checks and wet well cleans completed, to ensure they are working as they should.

In Alkham, we’ve completed our pre-winter season sewer cleaning and CCTV survey to check the condition of our network. We then completed the electro scanning of the sewer, and this work has helped us target the worst affected areas. We’ve now started relining 1.2km of the sewer, which we hope to complete in January.

Communications improvements

Across our region, we’ve been speaking with customers on the ground to look at how we can reduce potential impact (tankering / generator locations etc).

We’ve also improved customer communications with proactive SMSs messages to advise of any disruption (tankering, traffic management etc). Please note this has not been needed so far this winter in Kent.

Improved transparency by using our interactive Incident Map System on our website, which customers can access to show areas where we have live groundwater issues. Previously we did not use the incident map for groundwater incidents, but recognising the impact these issues can have on communities, we want to ensure live updates are available for customers.

We also have a dedicated Kent Customer Team email address, where residents can email if they have any queries or concerns – [email protected]

Proactive stakeholder updates throughout the winter, advising you of the latest position we are in. Weekly calls with the Environment Agency

Current status of groundwater infiltration in Kent

It’s important to note that in Kent we are starting this winter at a higher groundwater level, which means we are starting this winter in a tougher position.

Increased groundwater levels have not yet caused any issues to our sewer network or WPSs across Kent. However, the preparation of our operational team over the spring and summer months means we are ready to react if necessary.

Please be assured we will be working as hard as possible to reduce the risk of customer impact, and we will keep you updated over the coming weeks and months.

Version 7 of the Alkham Infiltration Reduction Plans – Southern Water has now been uploaded to our website.

Kind regards.

John Mealey

Stakeholder Engagement Manager – Kent