The Department for Environment, Food & Rural Affairs has published a progress report by Wessex Water on how it is adapting to the current and future predicted effects of climate change on their organisation - the latest water company update on its adaptation plans to be published by Defra.

The report sets out how Wessex Water is planning to adapt to climate change and covers  the climate-related hazards that could affect the company, the level of risk that each poses for the business and proposed adaptation options, together with those that are already in place.

Like other UK water companies, Wessex uses the UK Climate Projections (UKCIP02 and UKCP09) to help plan investment in water and wastewater. The reports are likely to be of particular interest to the water sector supply chain, providing a useful overview for key areas of the utilities’ current and future investment plans.

Wessex Water said that while climate change is not an explicit driver for the large majority of individual investment schemes, much of what it does could be described as ‘climate change adaptation by default’.

Impacts of heavy rain dominate Wessex Water’s risk assessments

Introducing the report, Wessex Water said resilience to the risks posed by climate change centres on its ability to continually provide excellent service for customers and the environment.

This is related to:

• the ability to plan ahead and then implement measures needed to increase resilience
• the physical capacity of the company’s assets
• the quality of its emergency response

According to the report, the impacts of heavy rain dominate Wessex Water’s risk assessments compared with warm or dry conditions. Temperature increase is a lesser concern for operational assets, but could affect peak demand and cause odour problems at wastewater assets.

Key medium to high risk climate-related hazards scoring 12 or more out of 25 based on the 2012 HR Wallingford / UKWIR climate risk assessment tool  identified in the update include:

Water resource quality - more likely to be compromised by climate change in the short to medium to long term, than water quantity. Warmer summers are likely to bring reductions in quality due to biological activity that is triggered also by warm weather. Heavy rainfall – both in prolonged episodes or short, sharp spells – can result in contaminants being washed into reservoirs or groundwater sources.

Sewerage, sewage treatment and sludge - the highest risks relate to inundation of sewers during intense or prolonged rainfall, with adverse impacts on customers and receiving watercourses. Others include odour during warm weather; reduced dilution in receiving waters during drought; and sedimentation in sewers, also due to drought.

The report says there are a number of options available to reduce the likelihood or consequence of a problem occurring. Some options involve building physical assets or improving systems; others are focused on catchment management; others are mainly about co-operation with external organisations and encouraging helpful behaviour among users of the water company’s services.

No flood resilience schemes for assets planned in AMP6

On water supply options and the risk of flooding of assets and sites, the report says improvements were carried out at two sites during 2010-15, involving installation of bunding, flap valves, alarms and drainage improvements. Wessex is not proposing any further asset flood resilience schemes during the AMP6 2015-20 investment period, describing its previous flood risk assessments as very comprehensive and still applicable.

The company’s 2008 risk assessment started by identifying 84 sewage treatment works and 164 sewage pumping stations that lie in a flood plain -reduced to eleven sites for improved flood resilience works during the 2010-15 investment period - two sewage pumping stations and nine sewage treatment works.

The report says Ofwat was unable to support the need for all but one of these schemes, challenging the marginal results of the cost-benefit assessment. The single scheme, involving a sewage pumping station that serves a medium-sized town, was completed in March 2013 and included replacing above-ground pump motors with dry well submersibles and raised electrical equipment above predicted possible flood levels.

However, Wessex Water will continue to monitor the vulnerability of sites to flooding in the medium to long term.

Water mains – replacement rate will need to rise from 2020 onwards

Commenting on water mains, the report says extreme weather impacts can play a part in the need for mains renewal or replacement, such as bursts caused by severe cold weather causing ground heave. Wessex is planning to keep the mains replacement rate at 50km per year in the next five years and maintain the current level of unplanned interruptions through improved prioritisation of work and the introduction of sensors in the water network.

However, from 2020 onwards, the mains replacement rate will need to rise as pipework ages, and mains rehabilitation designed to improve water quality will also need to continue.

Barriers to climate change

The report identifies the main barriers to climate change adaptation as financial, regulatory and technical.

Examples include the upfront cost of capital-intensive engineered measures; uncertainty and the limits of existing knowledge; delayed action due to complexity (particularly agencies with varied funding arrangements and cycles are involved); insufficiently clarity over responsibilities where there is more than one potential lead organisation; and potential unintended consequences of adaptation measures such as changes in movement of excess water.

The report says the issues can be addressed in part by improved evidence or risk assessments that indicate the highest priorities for action funding and closer co-operation between interdependent organisations to identify cost savings and risk reduction measures. Changes in economic regulation of the water sector also offer the potential for a wider suite of measures to be pursued.

PwC - lack of consensus on how to apply kowledge of climate risks is main challenge for water sector

It also draws attention to the Pricewaterhouse Coopers report “Adapting to climate change in the infrastructure sectors” which found that the main challenge for the water sector is a lack of consensus in how to apply knowledge of climate risks for planning and regulatory purposes.

The PwC report also says that some adaptation deals with impacts that might not actually occur within a 25 year planning horizon and that it can be difficult to identify the willingness, or obtain the consent, of customers to pay now for future resilience.

Integrated water supply grid set to play a key role

The Wessex Water adaptation report also flags up the contribution that integrated water supply grid, which is due for completion in 2017/18, will make to the company’s resilience to climate change impacts. The grid is expected to enable them to deal with a number of issues simultaneously, including:

• It will improve the security of supply to customers via reducing the number of customers reliant on a single source. The grid will also complement existing bulk supply agreements with neighbouring water companies.

• It will allow Wessex Water to accommodate abstraction licence reductions required by the Environment Agency to improve flows in some rivers and protect their ecology.

• It will enable surplus water to be used in the event of outages.

• It will 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. Together with catchment management, this will remove the need for construction of additional treatment plants.

The report also says that Wessex Water is expecting to see the increased use of monitoring technologies, allowing more rapid analysis of water quality, as well as real time monitoring of water volumes in the distribution network.

Forward planning includes energy self-sufficiency at key sites

In terms of forward planning, other measures Wessex Water is proposing to take with regard to investment schemes and ongoing operations for all its activities include:

• Flood risk assessments
• Asset deterioration models
• Adapting maintenance plans
• Local infrastructure solutions
• Energy self-sufficiency at key sites
• Optimising operating and maintenance regimes
• Climate change mitigation

The water company expects to generater enewable energy principally through anaerobic digestion and resource recovery at sewage treatment works, but is also pursuing other opportunities involving hydro, solar and wind.

Commenting on the risk to assets from coastal processes, Wessex says it has 391 significant sewerage assets or sites in the areas covered by shoreline management plans (SMPs). While the risk to all in the short term (0-20 years) has been assessed as low, in the medium term (20-50years), four assets are potentially at a high risk from coastal processes – one sewage treatment works, one sewage pumping station and two outfalls. Between 2020-30 the company anticipates developing options and plans to improve the resilience of the assets which are at risk.

Click here to download WESSEX WATER’S SECOND REPORT TO DEFRA UNDER THE CLIMATE CHANGE ADAPTATION REPORTING POWER