Storm Water Management Policy September 2014
2 Sustainable drainage feature designed to control and manage flows through a series of check dams
3 Document Name: Storm Water Management Controlled Copy No: 01 Revision No Date Description/Amendment Prepared Checked Recommended Approved 01 16.07.14 Main body B C Smith I Stevens Strategy Review & Alignment Group 03.10.14 Definition of Key Terms Asset Management Plan (AMP) A five year plan for managing infrastructure and other assets to deliver an agreed standard of service. AMP6 covers the period 2015-2020. Blue infrastructure A concept used to manage water on the surface, in a controlled manner, on specifically designed above ground flow pathways Combined sewer A sewer designed to carry foul sewage and storm water in the same pipe Development growth The addition of a new property where there was no previous property or the addition of impermeable areas associated with new properties (e.g. new housing or highways) Drainage Area Plan An investigation to assess performance of sewer networks and assist investment planning to meet regulatory and customer service objectives Drainage Strategy Framework Guidance published by the Environment Agency and Ofwat for the content and intention of Drainage Strategies Environment Agency The main environmental regulator and leading public body for protecting and improving the environment in England Exceedance Occurs when a drainage system does not have the capacity to receive more storm water Exceedance routes Flow pathways which protect people and property by providing unobstructed overland flow routes for storm water Green infrastructure Use of the natural environment to regulate flow, and treat storm water runoff closer to the source naturally, through the use of plants and soil media, so that cleaner water is discharged into our watercourses. These include natural features such as swales, detention basins, ponds and wetlands Grey infrastructure Traditional drainage systems such as pipes and concrete tanks Impermeable Will not allow water to pass through Infiltration The passage of surface water runoff into the ground Ofwat The economic regulator of the water and sewerage companies of England and Wales Permeable surface A surface allowing infiltration of rainwater to the sub-base and underlying construction or soil Runoff The water flow (resulting from rainfall or snow melt) over the ground surface which either flows directly into surface water bodies or is channelled into drainage systems Sludge Residual material from sewage treatment processes Storm Water Management A technical and organisational approach to managing the quantity and quality of storm water in order to reduce risk of flooding and pollution Swale A shallow vegetated channel designed to convey and retain surface water runoff, but may also allow infiltration Treatment Improving the quality of water by physical, chemical and/or biological means Urban creep The increase in impermeable area associated with existing development e.g. paving a front garden for parking
4 Contents 1. Purpose...... 5 2. Policy...... 5 3. Background... 6 4. Key issues... 7 5. Our conclusion...... 8 6. Future action... 9 7. Facts and figures...... 9 8. Risks and opportunities... 10 Natural wetland, Gosforth Valley, Dronfield, North East Derbyshire
5 1. Purpose The purpose of this document is to explain our policy position on a matter that we consider to be of strategic importance to our water and wastewater services. We have developed our policy position following an assessment of the best available information of relevant issues, threats and opportunities. The policy will be publically available and we will communicate it to employees and interested stakeholders. We will update our policy in the future as and when new information becomes available. Having published our policy we will now develop our long-term strategy to inform our future approach.
6 2. Policy - Storm Water Management Yorkshire Water s vision is Taking responsibility for the water environment for good. We provide an essential service by managing the region s sewerage system to safely remove waste water. Changing rainfall patterns and urban development is increasing volumes of storm water entering public sewerage systems, resulting in sewer flooding and pollution. We continually develop our long-term plans to maintain and enhance the quality of our essential drainage services for customers today and long into the future, enabling sustainable development in the region. Our development of a strategy for the management of storm water is central to our long-term plans because it is critical to our ability to maintain affordable and effective drainage in the changing climate and growing population. In line with our Company vision and Strategic Business Objectives, our policy is: We will work in partnership with others to create and deliver a strategy that ensures we can maintain and enhance our drainage service to meet the interests of our customers now and in the future. We will ensure that our approach will align with the principles of the Drainage Strategy Framework published by the Environment Agency and Ofwat. We will maintain and enhance our drainage service to protect customers from sewer flooding, and play our part in managing overall flood risk. We will enable continued improvement in our drainage service by enhancing our understanding of the sewerage network and expanding our portfolio of possible management responses. We will create long term plans that detail our drainage investment requirements over a 25 year period, basing our decision-making on sound evidence, engineering science and economic judgement. We will maintain and enhance our drainage service to protect the environment from sewer pollution. We will ensure future schemes consider the potential for managing storm water flows on the surface through a controlled process to optimise how we maintain and enhance the essential drainage service we provide. We will investigate ways in which we can capture and re-use storm water to reduce demand on potable water sources. We will ensure best use of resources by creating strategy that delivers the optimal combination of above and below ground infrastructure. We will maintain and enhance our drainage service through the best value approaches available to us, securing the standards of service that our customers expect at the lowest possible price. We will incorporate the above commitments into business-as-usual through our strategies, operations and investment plans to achieve our Strategic Business Objectives. We will communicate this policy to all employees, those working on our behalf, interested parties as appropriate, and it will be made available to the public. We welcome comments and suggestions for improvements and will review this policy periodically in light of new knowledge, changing legislation, and the views of the public and our stakeholders. Version 1 September 2014
7 3. Background Yorkshire Water provides an essential service by managing the region s sewerage system to safely remove waste water. This is critical to human health, flood protection and environmental management. Waste water consists of sewage and storm water. Sewage is the normal contents of lavatories. i.e. any water that has been contaminated with faeces or urine; and water which has been used for cooking or washing. Storm water is rainwater or snow-melt that enters the sewer system from roofs, roads or paved areas and may also be referred to as surface water. Waste water networks comprise a system of foul, surface water and combined sewers. Storm water management is an approach using a combination of above and below ground infrastructure to control storm water in order to reduce risk of flooding and pollution. Over the past 50 years our approach to managing storm water through underground sewers, tanks and shafts has led to great benefits in public health, improved river and bathing water quality, and flood control. We have delivered many investments in sewer capacity and storage to improve service and meet regulatory obligations. We are also managing a legacy of flows entering the network that are not designed or intended to be there. e.g. watercourses, highway drainage, inundation from storm water run-off from fields and adjacent land. It is now widely recognised across the water industry and its regulators that continuing solely with the traditional approach of maintaining and enhancing the sewerage network is unsustainable and there is a need for a change in the way storm water is managed. Open aspect feature to attenuate flow providing storage and pollutant removal and reduced flood risk New development design to receive and treat 680 acres of storm water run-off
8 4. Key drivers Flooding and pollution We face unprecedented challenges and uncertainty in a changing environment. Existing sewer infrastructure is aging and lacks flexibility in regard to the demands of a changing climate and population. There is an increased risk of sewer flooding and pollution if no action is taken. We, and our infrastructure, need to be flexible and adaptive. Storm water is an uncontrolled demand on public sewers and is the dominant cause of hydraulic incapacity within the sewer network. Storm water will have greater consequence in the future as the effects of climate change (wetter winters and drier summers with more frequent short, intense, rainfall events) and urban creep (more runoff from impermeable surfaces) lead to more flooding and pollution where the sewer network is close to capacity at times of peak volume. Storm water entering our combined or surface water sewer systems affects our customers and the environment by increasing the risk of sewer flooding and pollution. Storm water poses a threat to the functioning of our combined sewer systems, increasing flows to treatment and affecting our ability to achieve compliance with environmental and regulatory obligations. Increased frequency and volume of combined sewer overflow (CSO) discharges will create further pressures on the environment and quality of raw water. CSO performance is equally a key issue to flooding for the Department for the Environment, Food and Rural Affairs (Statement of Obligations, Defra October 2012) Sludge Sludge is generated at waste water treatment works as a result of the biological matter in sewage and the pollutant load. Storm water dilution affects the operation and performance of sludge treatment and increases pumping costs. Operational impacts Storm water contributes to increased carbon emissions, energy costs and chemical use through additional pumping and treatment. The reliance on energy intensive pumping and treatment processes to manage increased storm water flows to treatment is not sustainable from both a hydraulic and financial viewpoint. Coupled with population and development growth, changes in the global climate are having both direct and indirect effects on our local and regional water resources, our environmental impacts and affects the resilience of our sewer networks and critical infrastructure. Surface water run-off containing high levels of sediment, oils, hydrocarbons and other substances flows through our surface water sewers into our region s watercourses untreated. The abrasive nature of sediment causes premature wear on pumps resulting in reduced performance. The uncertainty of climate change and extreme weather may result in future shocks which could have a damaging effect on customer service, financeability and investor confidence. The principle that combined sewerage systems should accommodate future flows is unsustainable in the long-term context of climate change (Preparing for the future Ofwat s climate change policy statement). Complying with legal duties Landscape planters in footpath to take street run-off European legislation and regulations have placed increasing requirements to reduce
9 flooding; and river and bathing water quality impacts. UK primary legislation imposes a duty to provide a system that is, and continues to be, effective in draining our area to prevent flooding and pollution. The Flood and Water Management Act 2010 and Flood Risk Regulations 2009 have set duties for us to cooperate with other risk management authorities on the management of storm water. Government and regulators have updated and extended legal and regulatory requirements, for which a radically new approach is now expected in the management of storm water. The Ofwat and Environment Agency Drainage Strategy Framework expects sewerage undertakers to have strategies for managing storm water. Population growth Effectively managing storm water gives us the potential to create headroom in our sewer network which can be utilised to accommodate the increased load we anticipate through population growth. Our water resource management plan suggests an additional 855,000 will require access to our sewer network by 2040 (Yorkshire Water Water Resources Management Plan 2014). Storm water storage to reduce flooding and pollution. It also serves as a community open space during dry periods 5. Our conclusion Storm water draining to our sewer networks is a major cause of sewer flooding and pollution, critically affecting our customers and the environment. Our sewer network is largely an inherited legacy of predominantly combined sewers that were never designed nor envisaged to deal with the volumes of storm water now draining to the sewer. Storm water also contributes to increased energy costs and carbon emissions. Surface runoff is increasing as a result of urban development and climate change. It is not sustainable for sewer systems to accommodate the volumes of storm water now being received, let alone the substantial increases expected in the future. A long term, integrated approach is necessary to control the volume of storm water draining to the sewer system to reduce flood risk and pollution, and ensure sustainability of future growth. Working with our stakeholders we will develop a strategy to reduce storm water within our sewers and thereby reduce the risk of sewer flooding and pollution; also reducing pumping and energy costs to help keep customer bills as low as possible. Further enhancing our understanding of the capacity and performance of our sewerage network will enable us to advance a long-term approach and response plan to maintain and enhance the quality of the essential drainage services we provide. Long term control plans for storm water management through use of the most effective and cost-efficient combination of above and below ground infrastructure will enable us to deal more effectively with the challenges accelerated by climate change Our policy for the management of storm water is in line with the company s strategic objectives, customers priorities and is central to our vision: taking responsibility for the water environment for good. We commit to ensuring a more strategic approach to drainage planning and will base our decisionmaking on sound evidence, engineering science and economic judgement. Many organisations have important roles in the management of storm water and our approach will align with other stakeholders and the Drainage Strategy Framework published by the Environment Agency and Ofwat. Partnership working and the delivery of
10 integrated solutions can achieve the greatest benefits. We will work with our customers, delivery partners and other stakeholders, including the Environment Agency, local authorities, highway authorities, developers and homebuilders to create an effective and holistic strategy. Retention pond as part of residential development to reduce flood risk, improve water quality, enhance biodiversity, habitat creation and community amenity 6. Future action We will take a 25-year view of how we manage storm water in a changing climate to provide affordable, low risk solutions. We will use this to inform our detailed 5-year plans and will take the following themes of action: Develop a storm water management strategy detailing our plans and priorities for the longer term. To help test and objectively substantiate our risk and proposed approaches at the local (catchment) level, we will use and evolve our advanced Drainage Area Planning (DAP) approach to help test our risk. Integrate storm water management into our design and decision-making processes Develop relationships and work in partnership with internal and external stakeholders Enhance our capability to understand and articulate the performance of our sewerage network across the region, both now, and for an appropriate time into the future In addition, we will work with the UK water industry, its regulators and the government to influence Strategic and Policy direction and ensure the necessary regulatory and legislative controls are implemented to safeguard appropriate risk management. 7. Facts and figures We forecast a need to serve an extra 855,000 people for our water service by 2040 (Yorkshire Water Water Resources Management Plan 2014). 81% of our sewer network receives storm water flows 365 billion litres per annum of waste water is treated by us, of which a significant amount is storm water Foresight Flooding Project (2004) highlights a potential 40% increase in flow (accounting for climate change, growth and urban creep) leading to a 100% increase in flooding by 2080 8. Risks and opportunities Reducing the volume of storm water within the sewer network will mitigate risks and maximise opportunities to maintain customer service and environmental performance. More readily available capacity within the sewer network will reduce the need for future investment in piped systems and waste water treatment works upgrades. Increasing asset resilience and adaptive capacity will minimise sewer flooding and pollution, reduce pumping and energy costs and improve sludge quality at the same time as providing other societal benefits. The creation of more readily available sewer and waste-water treatment capacity will enable us to accommodate future development growth within our region and help us adapt our activities to the effects of climate change and ensure resilience, sustainability and future growth. If no action is taken, flooding, pollution, high power consumption and carbon output will continue to grow, accelerated in the future by climate change and urban growth.
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