Wessex Water has invested more than £500,000 to separate rainwater from the sewerage network at Portland Bill in Dorset to reduce the reliance on a combined sewer overflow (CSO).
The work is part of the company’s ambition to slash discharges by 25% from overflows by the end of this regulatory period in 2025. It is investing £3 million a month to reduce the operation of CSOs, beginning with sites in sensitive locations.
The scheme at Portland includes pipes to separate surface water runoff from an 8,000m2 area from the combined sewer system that carries waste from the southern part of the promontory.
The company has planned similar projects to complete before the end of this regulatory period in 2025 to meet government targets designed to minimise the risk of harm from CSOs.
New drainage and additional sewer storage is included in the Portland Bill scheme to reduce the operation of overflows.
Project manager Jonathan Barker explained the work would help stop sewers being overwhelmed during heavy rain, which should stop excess water needing to be released from CSOs.
The company has committed to eliminating discharges by investing more than £181 million to upgrade over 600 overflows since 2000; it will spend a further £150 million by 2025.
Wessex’s permitting manager, Andy Mears, said: “Removing overflows completely would take time and money, involve digging up roads and costing in excess of £10 billion as well as leaving an enormous carbon footprint so separating rainwater from foul water at source has a number of benefits for people and the environment, including lower water consumption, energy use and sewerage bills on top of a reduction in overflows use.
“We would like the government and regulators to encourage separation solutions by amending legislation and regulation to create the environment for the simpler delivery of these projects and are working with them to try and bring about these changes.’’
Alongside separation projects, the company is enhancing capacity at 14 treatment sites and adding storm water or sewage capacity to reduce CSO operation at a further 32 locations and nature-based solutions such as wetlands being introduced where appropriate.
The company monitors more than 90% of its CSOs and will monitor all overflows by the end of 2023.