Overflow solution reigns at Portland Bill Lighthouse

Wessex Water is separating rainwater from entering the sewerage network to reduce a nearby storm overflow operating.

It is part of the company’s £3 million-a-month drive to reduce the operation of storm overflows, which automatically operate during heavy rainstorms to protect properties from flooding, preventing sewage from overflowing into streets and homes.

One of more than a dozen projects up to 2025 being prioritised by Wessex Water to reduce the most frequently operating overflows, the two-month Portland scheme separated surface water, such as rain running off nearby roofs and roads, from the system that carries foul water from homes, businesses and the public toilets in the lighthouse car park.

Installing a separate pipe will see surface water from a potential 8,000m² area removed from the combined system that also carries foul water.

Further new drainage is also helping the separation process, while more than 14 cubic metres of additional storage space is also being added on the existing combined sewer to also help to reduce the operation of overflows and benefit the environment.

Project manager Jonathan Barker said: “The Portland scheme is one of two being planned by Wessex Water over the next two years targeting rainwater separation as part of the solution to the operation of storm overflows.

“The work we are doing will reduce the likelihood of the combined sewer being overwhelmed during heavy or prolonged rainfall, which could result in excess storm water being released into the sea.

“With Portland Bill within a Site of Special Scientific Interest (SSSI) and alongside the Isle of Portland to Studland Cliffs Special Area of Conservation (SAC), we’ve worked closely with Natural England and the Crown Estate to ensure that this project is completed sensitively to the local environment."

“This includes reinstating the grassland within the area of our project once it has been completed and we’ve also worked with businesses on Portland Bill to minimise any impact on them while the scheme has been in progress.’’

The Portland project forms part of Wessex Water’s Storm Overflow Improvement Plan, which aims to deliver a 25 per cent reduction in the number of hours of discharges from storm overflows by 2025.

The company is committed to completely eliminating the discharge of untreated sewage, investing more than £181 million upgrading more than 600 storm overflows since 2000, with a further £150 million to be spent up to 2025.

Wessex Water’s Permitting Manager, Andy Mears, said: “Storm overflows have always been part of the sewerage network in this country and the majority of sewers carry combined rainwater and foul sewage, with around half the houses in England being combined.

“In an intense rainstorm, one property’s flow with combined surface water and foul drainage is equal to 100 separately drained properties’ flow.

“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 such as Portland, Wessex Water is also pursuing further solutions, with the capacity to treat water at 14 recycling centres being enhanced and increased storm water or sewer capacity to help reduce overflow operation also being put in place at a further 32 sites.

Nature-based solutions, such as wetlands, are also being explored at rural sites where the infiltration of groundwater is the primary cause of overflows, while Wessex Water is also starting a pilot project to separate rainwater at source by installing water butts and soakaways at properties.

In addition, the monitoring of storm overflows in the Wessex Water region is being beefed up from 90 per cent to all of them by the end of 2023, along with new innovations allowing more real-time public health monitoring.