Ampney St Peter drainage strategy. Our next steps. 2019 Contents. Summary 2 About our strategy 4 The Ampney St Peter area 7 Our drainage investigations 9 Findings and interventions 13 Our next steps 15 You can help 16 Appendix 18 1 Summary. We’re working on how to reduce the risk of sewer flooding, pollution, blockages and restricted use of toilets and bathrooms in the Ampney St Peter area. For us, it’s a priority. We’ll continue to work with our customers and other stakeholders, such as the Parish Councils, Cotswold District Council, Gloucestershire County Council and private land owners, to take action and make drainage improvements as quickly as possible. Our drainage strategy work We began our drainage strategy work Over the last year, we’ve undertaken in 2016 by carrying out research and detailed investigations which have meeting with customers who had been helped us to understand the drainage affected by drainage issues, as well as problems in the area served by the stakeholders in the local area. Ampney St Peter sewage treatment works, and find the best ways to prevent them from happening in the future. Our drainage proposals Based on our recent investigations • Implementing sustainable and findings we’re proposing that drainage systems (often called a number of drainage activities SuDS*), in customers’ homes and are carried out (we call these businesses, to reduce the rain interventions), that will help to reduce water entering our sewers from the drainage issues in the Ampney St property roofs Peter area in the future, these include: • Monitoring groundwater levels • Repairing any sewer defects so that we can try to predict and we find, particularly in areas prevent the flooding and drainage where our inspections identify issues that happen in the area, groundwater entering our sewer when groundwater levels are high. network • Installing monitors into our sewage pumping stations so that we can continually check how they’re operating * SuDS are a range of drainage methods that can be used for slowing the speed at which surface water enters our sewer network, and/or redirecting 2 surface water away from our sewers. Examples of SuDS include using water butts, planters and paving that allows water to pass through it. Assessment and selection The long-term interventions that we’re In this drainage strategy proposing will be assessed to make sure document we outline: that their potential benefits outweigh their costs, and then prioritised. Those • The drainage process we’re using • Our proposals and next steps selected will be put in place during for making future drainage our next Business Plan period, which is • The villages that make up the improvements in the area between 2020 and 2025. Between now Ampney St Peter area and then, we’ll also continue to work • How our customers can also closely with local stakeholders to deliver • The things that can cause sewer help to improve drainage in the short-term drainage interventions and flooding, blockages, pollution and Ampney St Peter area now, and in improvements in the Ampney St Peter restricted toilet use the future. area. • Our recent work in stage two and You can help three of the process, particularly the investigations we’ve carried benefits out and what we’ve found costs priorities 3 About our strategy. We’ve followed the guidance from our regulators, Ofwat and the Environment Agency, to produce this drainage strategy. The good-practice process they We’ve also combined stages two and recommend has four stages*. We three of the process, as their activities completed the first stage in 2016, which are closely linked. included a range of background research into the drainage issues in the area. From 2018 ** 2015 - 2017 onwards Stage 1 Stage 2 Stage 3 Stage 4 ‘Initialise/ ‘Risk ‘Options ‘Intervention’ prepare’ assessment’ appraisal’ We're here What this means Initialise/ Risk Options Intervention prepare assessment appraisal Starting the Identifying Developing Implementing process the things that different selected drainage including could prevent options for improvements gathering drainage making based on their information improvements, drainage potential benefits and forming and how to improvements outweighing their relationships manage that work and costs and their with them are value for priority stakeholders money * ofwat.gov.uk/publication/drainage-strategy-framework-for-water-and-sewerage-companies-to-prepare-drainage-strategies. ** The estimated delivery timeline is dependent on factors including weather conditions, risks and costs, and is, therefore, open to change. Drainage Strategy Framework stages and timescales 4 In the combined stage The final stage of the process, stage The proposed long-term drainage two and three of the four, will start from 2018 onwards. This interventions will then be reviewed process we’ve: is the intervention stage when we’ll and prioritised against the other carry out some short-term drainage investments we need to make across • Carried out detailed interventions ourselves, and work our business, to benefit all of our investigations, assessed the closely with local stakeholders as customers. risks in the area such as its appropriate, to deliver others. growing population and rising The interventions that we select for groundwater levels, and looked at We’ll also assess the long-term the Ampney St Peter area will be put in how to manage them interventions we propose to make sure place between 2020 and 2025. If one that their potential benefits outweigh or more of our proposed interventions • Found the root causes of the their costs, which will be paid for by all are not selected, we’ll use our drainage issues and proposed of our customers. Potential benefits increased understanding of the local options to improve them, based will be assessed based on a range drainage issues to help us continue on if they’re long-lasting and of factors including the number of our work in reducing flooding in the value for money. properties affected by drainage issues, Ampney St Peter area and preventing the frequency that flooding might be service disruptions for our customers. expected to occur in the future, and its severity. 5 Who else is involved? Making drainage resilient in the Ampney St Peter area for the future requires close co-operation with a number of key stakeholders. They include the local councils, private land owners and people with rivers and streams on their land (also known as riparian owners). Our role is to make sure that the Water that enters our sewers that are within our control, and support sewers and other assets we operate, unnecessarily or by mistake, stops them stakeholders to deliver those that sit such as wastewater treatment works from working properly. This can lead to outside of this, so that together we and sewage pumping stations, are them overflowing and causing other can make the drainage improvements kept in good condition, work efficiently drainage issues. We’ll continue to work needed in the Ampney St Peter area. and are resilient. hard to resolve the drainage issues Other stakeholders can help to improve drainage in other ways such as: • Stopping rainwater from running into our sewers from roads and private land Thames Water Customers • Clearing ditches and streams that can cause blockages if left to grow wild Council/ Land and Highways Riparian Drainage England owners • Connecting pipes correctly from stakeholders homes and businesses, rather than into our sewer system. Council/Lead Charities local flood authority Environment Agency Drainage stakeholders 6 The Ampney St Peter area. We serve over 2,000 customers in the area served by the Ampney St Peter sewage treatment works, in Gloucestershire. The wastewater is transported through 18 kilometres of sewer pipes and ten sewage pumping stations. It then ends up at our sewage treatment works, where it’s cleaned and treated before being returned safely back into the environment. We’ve improved and extended Our sewers have become overloaded The Ampney St our network in the area since it at times for a number of reasons, Peter area includes: was originally built, by replacing unfortunately leaving some of our some sewer pipes and building new customers with drainage issues such • Ampney St Peter pumping stations, yet it remains under as sewer flooding, sewer blockages • Ampney Crucis increasing pressure. and restricted use of their toilets and bathrooms. • Ampney St Mary • Driffield • Poulton • Meysey Hampton • Down Ampney. Ampney St Mary Ampney Crucis Ampney St Peter Poulton Driffield Meysey Hampton Down Ampney The Ampney St Peter area* 7 * Source: Contains Ordnance Survey data Crown © copyright and database right (2015) ordnancesurvey.co.uk. Causes of drainage problems. There are many things that In certain conditions, one or more of That’s why we’re working together can cause drainage issues, these can prevent our sewer network with other stakeholders to manage a number of which are not from working as it should and can these issues and to improve drainage sadly cause sewer flooding in our across the Ampney St Peter area. under our control. They can customers’ homes and businesses, Together, we can prevent these include: on local highways and in surrounding unacceptable situations from environments. happening again in the future. • More periods of prolonged and heavy rainfall • Growing numbers of people, houses and businesses entering the area Intense • Loss of green spaces that rainfall previously provided natural drainage for rainwater as new paths, extensions and houses are built Loss of • Blockages in the sewer network, green often due to fats, oils and grease spaces Population growth being poured down drains Surface and ground water • Misconnected pipework that flooding allows untreated wastewater to enter local rivers and streams • River water and groundwater Misconnected entering our sewers. properties River Sewer flooding blockages Causes of drainage problems 8 Our drainage investigations.