Welsh Water study to reduce surface water flows in sewers

Cardiff, UK - Dwr Cymru Welsh Water has engaged MWH to carry out an £800,000 study with the aim of reducing the amount of surface water flows that enter the sewers in Wales. The ‘Surface Water Management Strategy’ is led by MWH from its office at Llanishen, Cardiff.

“Surface water entering the sewerage system as a result of rainfall is one of the main causes of sewer overloading," explains Huw Jones MWH principal engineer. "This long term strategy will help to address the situation, reducing flooding and pollution, decreasing energy costs and supporting conservation and recreational opportunities.”

The project will also be instrumental in adapting people’s activities to address climate change. Surface water flows are set to increase as result of new housing development, and ‘creep’ - paving over of gardens for other uses such as parking and patios -  which reduces the area for natural soak away, as well as the impact of climate change.

“This study will look at a variety of ways that this problem can be addressed as reducing surface water flows is an essential part of any flood reduction strategy – dealing with the problem by building bigger sewerage systems is simply unsustainable in the long term”, said Jones.

The project will explore various options and strategies, among them encouraging commercial and domestic customers to minimise the amount of surface water discharged from their properties. It will also look to develop an awareness and engagement campaign with concerned parties, looking at legal issues and control of surface water between parties, reviewing charging systems and looking at a variety of technical initiatives including retrofitting rainwater harvesting facilities.

“Overall this is a demanding project because ultimately it calls on us all, as customers to change our behaviour and be willing to consider the impacts that discharges of surface water from our properties will have if discharged into the public sewers. We are not asking people not to build that conservatory or pave over the front garden to create off road parking, but to consider the impact of these actions on surface water flows and to consider alternatives ways of managing surface water” concluded Jones.

Commenting on the study Dave Bayliss of Welsh Water said: “We believe that reducing the quantities of surface water that enter the combined sewerage system is vital. It can be achieved through radical changes in the way that the network is managed, as well as how connections to the system are managed, and can offer sustainable solutions to some of the serious sewage flooding problems suffered by our customers.

“The individual initiatives that we are pursuing as part of our surface water management strategy are not all new to the industry, but we believe that the comprehensive approach that we are adopting is. The current work forms the second phase of the strategy and we see it as an approach that will transform surface water management in the longer term for the benefit of our customers and the environment."