Pan Parishes, Hampshire

The challenge

The Pan Parishes in Hampshire suffer from sewer groundwater infiltration. Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. Groundwater infiltration of our sewers happens when water from the ground squeezes its way into the network through underground pipework.

If the sewers fill with groundwater then there is less space for rain and wastewater, so the system is more likely to become overwhelmed when it rains. When this happens, we need to deploy tankers to remove the excess water, which can impact residents. If the level gets very high, it can also result in the need to release excess water to a local watercourse. These events are similar to storm overflow releases but the root cause is different.

This project is investing in relining and resealing of both public and private sewers to reduce this infiltration, monitoring through boreholes, pipe cameras and temperature sensors to spot problems before they arise, and investigating the construction of a wetland to absorb, hold and pre-treat excess groundwater.