Southern Water has published a Water Infiltration Reduction Plan for the Alkham Valley.

This Infiltration Reduction Plan (IRP) for Alkham Valley has been prepared in response to the Environment Agency’s (EA) Regulatory Position Statement (RPS). Southern Water has been carrying out work for many years to survey and repair sources of infiltration in the vicinity of Alkham Valley and notably in the catchment for Newnham Valley Wastewater Treatment Works (WTW) in Kent which is adjacent. Figure 1 shows the Town of Dover of which Alkham Valley is a part.

Wastewater flow from the Dover sub-catchment drains to the wastewater recycling centre at Broomfield Bank which also treats flow from the neighbouring town of Folkestone. Figure 2 shows the location of Alkham Valley to the west of Dover Town. Development within the valley is a ribbon style along the valley floor and includes the settlements of (from upstream to downstream) South Alkham, Alkham and Wolverton.

The village of Ewell Minnis sits above the valley floor and flows from here connect into the system serving Wolverton. All wastewater flow arising in the villages are conveyed by gravity to a wastewater pumping station at Kearsney named Kearsney Abbey WPS. Flows arriving at the WPS are pumped for a short distance over the local watercourse draining through Alkham Valley and then connect with the wastewater flow from Kearsney and areas to the north of Dover. All flow from this point gravitates to the terminal pumping station at Elizabeth Street Dover, the system runs roughly parallel to the River Dour.

The Alkham Valley sewerage network has not had an Infiltration Reduction Plan previously. However, in winters of 2019/20 and 2020/21 some instances of external flooding did occur from the sewer network due to the high groundwater levels. This external flooding has the potential to run overland into the watercourse in the valley floor and have an environmental impact. It was agreed that because of this a plan to tackle the infiltration in the system was required.

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