Getting on the grid

Wessex Water’s £225 million water grid will span two asset management plan periods and help protect customers against climate change and extreme weather. By Julian Welbank.

It is Wessex Water’s largest ever project and involves 50 schemes across Somerset, Wiltshire and Dorset. New pipelines are being laid, water storage tanks constructed and pumping stations built as part of a £225 million water supply grid project.

The water supply grid will allow Wessex to improve resilience as part of a holistic approach covering security of supply, drinking water quality and water resources. And it addresses multiple outcomes through a single project spanning two asset management plan periods.

For customers, regulators and government, it is important that essential services such as water can cope with acute, disruptive events, as well as more gradual long-term changes.

The importance of a resilient water supply has been underlined by customer research, which consistently shows that reliable water and sewerage services are seen as a basic requirement. But challenging weather has been experienced in recent years, and this could become more prevalent because of climate change.

Continuing to improve the resilience of Wessex’s water and sewerage systems is something we taken very seriously by the company as it seeks to manage risk. It requires investment to ensure customers get a service they want and are prepared to pay for.

The need for an integrated water supply grid was identified by a review of services and risks, which showed that around 260,000 customers were still served by single sources, the failure of which could lead to prolonged loss of supply.

Additionally, there were environmental and drinking water resilience issues to be resolved. The Environment Agency requested that the company reduce its existing abstractions by 24Ml/d (4 per cent) to improve river flows in certain locations on the Hampshire Avon and its tributaries. When combined with deteriorating raw water quality, the total loss was around 66Ml/d (12 per cent).

An integrated approach, which aligned the strategies for each issue and maximised synergies, as opposed to providing individual solutions for each of the drivers, maximised the benefits to customers. The integrated approach was also better from an environmental and social perspective. And spreading this investment over two price review periods meant the impact on bills could be minimised.

Construction of the multi-million pound project is well underway, and once complete will allow Wessex to move water around the region from areas of surplus in Dorset to where it is needed in Wiltshire, ensuring water demand is met for the next 25 years.

It means surplus water can be used to cover for outages and the low flow reductions. It will also enable alternative water supplies to be delivered to areas that are currently supplied by sources at risk of breaching the nitrate limit in drinking water, which together with catchment management, will remove the need for new treatment plants and keep the cost of production down for the future.

The eight-year programme of work, which started in 2010, includes the construction of more than 200km of pipelines, 24 major or refurbished pumping stations and 12 storage tanks ranging in capacity from 2 to 8 million litres. For the new pipelines, there are more than 120 crossings, including major trunk roads, major rivers and main railway lines.

Since the projects started, Wessex has held consultations with local community members and stakeholders to inform them about the work in their area. Animated videos were created and posted on a dedicated section of the company website, as well as an interactive diagram showing the route of the pipeline, so people could see what construction would involve.

During the 2012 drought there were calls for a national water supply grid and for companies to work with each other to meet water supply demand. For many years Wessex Water has been working with neighbouring water companies, and as part of the water supply grid project has joined forces with Sembcorp Bournemouth.

This has allowed Wessex to develop a support agreement for alternative reciprocal water resources that will provide the required level of resilience without major water treatment works redevelopment. By working together, they have been able to deliver a better value solution, minimising investment to the benefit of the customers of both companies.