Ampney St Peter Drainage Strategy

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. Over the last couple of years, we’ve carried out many detailed investigations in the Ampney St Peter area. They’ve given us a clear understanding of the root causes behind the drainage issues. They’ve included:

Customer and Flow and Impermeable area stakeholder asset surveys surveys consultations We checked the performance of our We measured the size of the We sent sewer-flooding questionnaires sewer network and the main assets we impermeable area in Poulton, that’s to our customers in the Ampney St operate in the Ampney St Peter area. connected to our sewers. This included Peter area. We wanted to hear their We placed three rain gauges, six flow property roofs and driveways made out drainage views and experiences, and monitors and eight sewage pumping of concrete or tarmacadam. As rainwater to pinpoint problem locations. We also station monitors across the area. We flows from these areas into our network, met and presented to local Parish carried out manhole inspections, rather than naturally draining away, it Councils, and gained feedback from pumping station surveys and, using reduces the capacity and performance other stakeholder groups in the area. CCTV, surveyed around 3,500 metres of our sewers and contributes to the of the local sewer network. We also drainage issues in Poulton. trialled some new survey technology in the local sewer network, that can help to identify pipe defects. This work helped us to understand if our assets were contributing to the area’s drainage issues.

Site Flooding walkovers 'trigger-levels' We investigated beyond our sewer analysis network to find the root causes of We analysed the groundwater levels other drainage issues in the area. and river levels that were recorded To help us to do this we hosted during periods when there was ‘walkovers’ at flood sites with some flooding and other drainage issues of our customers and the Farming in the area. We wanted to use this & Wildlife Advisory Group. information to help us define groundwater thresholds or ‘trigger levels’. If these levels are reached in future, it could trigger our local response teams to carry out specific work to help prevent the flooding and drainage issues, such as removing excess water from our sewers using lorries that carry large water tanks (we call them tankers). 9 Assessing drainage risks. Alongside our investigations, we’ve assessed the risks to the success of our drainage strategy. We’ve looked at a broad range from We’ve assessed each risk for its climate change and rainfall patterns, likelihood and how severe its impact right through to those risks we’ve could be on the Ampney St Peter area found at individual property level. in the future.

The main risks we’ve identified are:

Rainfall patterns

Stakeholder Population dependency growth

Drainage risks Urban creep Private land issues

Customer inﬂuences

Assessing drainage risks

10 Managing drainage risks. We’re managing the main risks that could prevent our drainage strategy from being successful. A number we can do by ourselves, and others we’re tackling with other stakeholders. By managing these risks together, we’re confident drainage improvements can be achieved in the Ampney St Peter area now, and in the future. The main risks we’re managing are:

Rainfall Population Stakeholder patterns growth dependency Intense, ongoing or above average As the Ampney St Peter area increases We’re unable to tackle all of the rainfall patterns can overload our in size from growing numbers of drainage issues ourselves, instead we sewers and contribute to them people, houses and businesses, the depend on a number of stakeholders flooding. Some recent climate change demand on our sewer network also to work with us to improve drainage analysis suggests that rainfall could increases. across our region. become 20% more intensive by the 2050s*, increasing the potential for We’re managing it by We’re managing it by flooding. And so, we’re working hard Basing our plans on national Fully supporting other stakeholders to to prepare for the effects of climate population data and working with deliver their responsibilities by change and to deliver our services to Local Planning Authorities and providing information that may help our customers during the worst developers to prepare for growth in them, championing their customer weather conditions. the area. This will help us to maintain campaigns and jointly funding our services for all of our customers – activities, where possible. We’re managing it by existing and new. Maintaining our sewer network on an ongoing basis to keep it operating properly, including cleaning it with high-powered hoses to remove silt, and fixing any damaged pipework we find. Also working with other stakeholders to reduce the amount of water entering our sewers. These actions will give us the sewer capacity we need to manage increasing rainfall and help improve drainage in the Ampney St Peter area.

11 * UK Climate Change Risk Assessment 2017: Evidence Report: Flood Risk, Appendix C – Climate Change Projections October 2015. Private land Customer Urban issues inﬂuences creep Some private land activities affect Without knowing it, some of our When green areas are paved over drainage, but sit outside of our customers are contributing to the with impermeable materials that control, such as agricultural land drainage issues in their area. By don’t naturally drain, such as concrete practices and maintaining private pouring cooking fat, oil and grease and tarmacadam, more rainwater ditches and streams. down the drain, and other enters our sewer network and reduces ‘unflushables’ such as wet wipes, its capacity. We’re managing it by sanitary items and cotton buds, our sewer network and reduces its Working with local councils, private sewers can get blocked. We’ve around capacity.We’re managing it by landowners and riparian owners to 80,000 sewer blockages in our region Working with local councils and other make sure that private land practices every year, which prevent sewage stakeholders to make sure that urban support our drainage work. For from flowing freely, and can cause creep is kept to a minimum. We’re example, clearing streams and ditches waste to back up. This can flood also working with our customers to of debris and vegetation helps to streets, rivers, gardens and in the encourage them to use water butts to prevent water flooding from highway worst cases, inside people’s homes. collect rainwater from their property drains entering our sewers. roofs and to use permeable materials Misconnected properties are for new driveways and paths. This will common, a report suggests 140,000 reduce the amount of rainwater properties in the UK are currently entering our sewers and the possibility misconnected*. This means their of flooding during periods of wet drainpipes are incorrectly connected weather. to our sewer network, reducing its capacity and leading to sewer flooding during heavy rainfall. Did We’re managing it by Providing our customers with you information and tips to help us keep our sewers running clear, and working know? with local councils to ensure misconnected pipes are fixed. We’re also encouraging our customers to disconnect rainwater pipes from our You’ll need planning sewers and to use other water-saving permission from your devices to reduce the water entering local council to use our network. impermeable materials in your home improvements.

12 * UKWIR, 2013. Sewer Misconnections: What is the True Non- Agricultural Diffuse Water Pollution Impact? Report 13/SW/01/3, UK Water Industry Research (UKWIR). Findings and interventions. We’ve found the root causes for the drainage issues in the Ampney St Peter area and put together some proposals to improve them. Our proposals consider the risks in the area, the ability to create long-lasting improvements and value for money. We’re confident the options we’re proposing to be delivered in stage four of the process will achieve effective drainage improvements for the Ampney St Peter area for many years to come.

Rising ground- Maintaining water levels our assets We found We found Groundwater can enter our sewers when levels are high which Our assets such as sewers, manholes and pumps can be damaged reduces their capacity and increases their risk of flooding. There’s in many ways, from age deterioration and blockages, to roadworks a strong link between the rising groundwater levels across the and tree roots. We’ve identified a number of defects which are Ampney St Peter area and the drainage issues some of our allowing groundwater to enter our sewers. We’ll continue to inspect customers have experienced, including sewer flooding and our assets and fix any problems we find. restricted use of their toilets and bathrooms. Our proposed interventions There’s a history of flooding and drainage issues at a property in • Reinforcing sewer repairs with watertight lining. For more details southern Poulton. An intervention was designed and put in place in please see the ‘Lift & Look surveys’ section in the Appendix. 2011 with the aim of resolving the issues. Unfortunately, flooding • Installing new monitors at our sewage pumping stations (SPS), and drainage issues have continued at this property. as identified in red on the map. This will help us to keep a close check on how our sewage pumping stations are working and Our proposed interventions alert us to any issues, or if any upgrades are needed. • Monitoring groundwater levels in our control centre and Ford Farm Ampney St (Ampney Mary SPS informing our response teams if thresholds are passed. The Crucis) SPS School Lane teams will carry out an action plan specifically designed for the (Ampney St Peter) SPS Ampney St Peter

area to reduce or remove the flooding issue, such as checking Ampney St (Poulton) SPS Peter sewage Meysey sewer water levels and using tankers to take away excess flows treatment works Hampton SPS from our sewers. • Installing monitors in our sewage pumping stations to help us to identify when our pumps are operating more than we expect them to. This could mean that groundwater is entering our sewers which shouldn’t be there. We’d investigate further to find

out the root cause of the drainage issue affecting our sewage Down pumping stations. Ampney SPS • Investigate further and put in place a new sewage network Proposed sewage pumping station monitor installation. solution to prevent flooding and drainage issues at the affected property in southern Poulton. Benefits of proposed interventions • Increase the capacity of our sewers and reduce the risk of sewer Benefits of proposed interventions flooding. • Give us the capability to predict and prevent some sewer • Improve our capability to monitor how our sewage pumping flooding issues before they occur, through monitoring stations are operating. For example, we’ll be alerted when groundwater levels and sewage pumping station flows. they’re operating for longer periods than expected, this can be • Increase the capacity of our sewers and reduce the risk of sewer due to too much groundwater entering our sewers and would be flooding when tankering is used to remove excess flows from our investigated further. We’ll also receive alerts when our sewage sewers. pumping stations are not operating as they should, and if • Reduce the risk of sewer flooding at the affected property in maintenance or upgrades are needed. southern Poulton. • Help us to maintain our wastewater services to customers in the • Help us to maintain our wastewater services to customers in the Ampney St Peter area during wet weather. Ampney St Peter area during wet weather. Delivery timeframe Delivery timeframe Proposed for 2018- 2025. Proposed for 2018- 2025. For more information on the ‘Lift & Look’ and For more information on the Flooding ‘trigger-level’ survey and CCTV surveys that we carried out as part of this analysis that we carried out as part of this work, please see the work, please see the Appendix. Appendix. 13 Rainwater Pumping station from roofs operation We found We found The downpipes on property roofs can be mistakenly connected School Lane sewage pumping station, which serves Ampney to our sewers. The Impermeable area survey that we carried out St Peter, Ampney Crucis and Ampney St Mary, can become in Poulton, showed that there are a number of misconnected overwhelmed during wet weather conditions. This has resulted in property roofs currently contributing significant volumes of some properties in Ampney St Peter being affected by flooding, rainwater into our sewer network. This is reducing the capacity of and having restricted use of their toilets, showers, baths and sinks. our sewers and adding to the area’s drainage and flooding issues. Our proposed intervention Our proposed intervention • Research and design a new sewage pumping station to serve Working with Poulton Parish Council to: Ampney St Mary and Ampney St Peter. We’re proposing that • Investigate if roof drainage can be separated from the sewer the School Lane sewage pumping station continues to serve network. It may be possible to do this jointly through customer customers in Ampney Crucis. campaigns and the installation of SuDS for our customers in affected areas. The type of SuDS that we propose are planters, as illustrated, which would be connected to the downpipes of affected property roofs.

Existing downpipe Proposed new sewage pumping station and connection. Benefits of proposed intervention • Increase the capacity of our sewers in Ampney St Peter. • Reduce the risk of flooding in Ampney St Peter. • Help us to maintain our wastewater services to customers in the Proposed SuDS planters for misconnected roof drainage. Ampney St Peter area during wet weather. Benefits of proposed intervention • Increase the capacity of our sewers and reduce the risk of Delivery timeframe sewer flooding by limiting the volume of water that enters our Proposed for 2017- 2018. sewers from misconnected property roofs. • Help us to maintain our wastewater services to customers in Poulton during wet weather.

Delivery timeframe Proposed for 2020- 2025. For more information on the Impermeable area survey that we carried out as part of this work, please see the Appendix.

14 Our next steps. In 2018 we started the final stage of the drainage strategy process, stage four. This is the intervention stage when we’ll carry out some long-term drainage interventions ourselves, and continue to work closely with local stakeholders to deliver others that are outside of our control. Our first activity is to assess all of planning. In response, by 2022, and Therefore, the long-term drainage our proposed long-term drainage at regular intervals after that, each interventions that we select for interventions. As well as looking at water company in England and Wales implementation in the Ampney their potential customer benefits and will produce a new document called a St Peter area within our drainage investment costs, we’ll also assess Drainage & Wastewater Management strategy, will also feature in greater how they support the fundamental Plan (DWMP)*. This will build on the detail in our DWMP when it’s aims of the 21st Century Drainage good-practice drainage strategy introduced. The new planning process Programme*. framework process we’ve been using, and DWMP documentation will then and the drainage work we’ve already We’ve joined together with more carried out. replace the existing drainage strategy than 40 organisations from across process and documentation. the water industry to support Our DWMP will detail the current this groundbreaking programme. and emerging drainage risks Our chosen interventions for the We all recognise the current and across our region, our customers’ Ampney St Peter area will be put in future challenges we face from drainage issues and needs, the place during our next Business Plan factors including climate change operational requirements we have period, which is between 2020 and and population growth, and we’re and the technological and innovative 2025. We’ll work with our customers committed to creating more resilient advancements we’ll use. Overall, and other stakeholders to implement drainage systems to cope with them. our DWMP will detail the long-term them as swiftly as possible during interventions we propose to achieve that time. Between now and then, The 21st Century Drainage Programme safe and reliable drainage and we’ll also continue to work closely has also highlighted the need for water wastewater services within our region, with local stakeholders to deliver companies to adopt a consistent for many years to come. approach to drainage and wastewater short-term drainage interventions and improvements in the area. Over the coming months our work in the Ampney St Peter area will continue to be focused on: Further drainage Stakeholder investigations engagement Carrying out further drainage Agreeing how we’ll deliver the investigations, including checking the chosen interventions with other performance of our local pumping drainage stakeholders. Attending stations. We’ll make sure that they're meetings with Cotswold District working at their best and not more Council, Gloucestershire County than they should be, which can often Council and the Parish Councils mean water is entering our sewers that within the area, to update on our shouldn’t be there. We’ll investigate findings and progress. We’ll also further any issues we find to help us to offer advice on how everyone can improve drainage in the Ampney St help improve drainage in the area. Peter area.

Flooding Maintaining our ‘trigger-levels’ plan assets Improving the accuracy of our Ongoing sewer inspections in the flooding warnings or ‘trigger levels’, x area and fixing any problems we and planning how we can best find, to stop them from causing respond if they're triggered. This will drainage issues. help us to manage the flooding in the area and reduce other drainage issues. x Our next steps

* You can find out more about the 21st Century Drainage Programme and Drainage & Wastewater Management Plans, by using the following link: 15 water.org.uk/policy-topics/managing-sewage-and-drainage/drainage-and-wastewater-management-plans. You can help. We’ve received a lot of support for our drainage work and we know that some of our customers, and other drainage stakeholders, are already working hard in a number of areas. However, our findings from this stage suggest that there’s still more to do, and by doing it we can improve drainage in the Ampney St Peter area, and across our region, now and in the future. And so, there are lots more things everyone can do to help improve drainage, including taking the following simple steps.

1. Use water-saving 2. ‘Bin it – don’t 3. Check your gadgets block it’ plumbing There are number of water-saving We’re working hard to keep our Some of our customers have their gadgets you can use in your homes sewers running clear from nasty rainwater pipes incorrectly connected and gardens, and some are free blockages and to help people to our sewer network. This plumbing to our customers. By reducing the understand what can and can’t mistake reduces the capacity of amount of water entering our sewers go down the drain. Things such as our sewers and can lead to flooding we can free-up capacity to manage cooking fat, oil, food waste, wet wipes during heavy rainfall. We’re providing heavy rainfall, and reduce the volume and make-up pads all mix together our customers with information that’s flushed away for treatment. in the sewers to create blockages. and tips to help them work out if By connecting your downpipes to These can grow so large that the their property is connected properly, a water butt you can collect a free sewers become completely blocked. and what to do if it isn’t. We’re source of water for watering your Once this happens the consequences also working with local councils to garden. This could not only help to can be devastating, as raw sewage is ensure misconnected pipes get fixed. save money on your water bills, but forced back up into people’s homes. You can check if your property is also help us to reduce the amount If it’s not poo, pee or paper, please connected properly by using this link: of rainfall entering our sewers. To ‘Bin it – don’t block it’. find out more, and to apply for our connectright.org.uk. free water-saving gadgets please use For more information on how you these links: can help us, please follow this link:

freebies.thameswater.co.uk. thameswater.co.uk/binit.

thameswater.co.uk/My- Account/ Customer-Offers/ Customer-Offers.

16 4. Choose drainage- 5. Take care of friendly home watercourses improvements on your land If you’re planning to pave over If you own land or property next to your garden for a driveway or an a river, stream or ditch you’re called extension, choosing materials that a ‘riparian landowner’. This means allow rainwater to drain through you’ve certain responsibilities for them will help us to tackle drainage taking care of the watercourse on issues in your area. You’ll need your land, and preventing its water planning permission from your local from entering our sewer network. To council to use impermeable materials find out more about the duties of a in your home improvements, such as riparian owner please refer to this concrete or tarmacadam. They don’t government guidance: allow rainwater to drain away, instead it can run into our sewer network. gov.uk/government/ For more advice on drainage-friendly publications/riverside- home improvements please follow ownership-rights-and- these links: responsibilities. planningportal.co.uk/ info/200130/ common_ projects/45/paving_your_ front_garden. developers.thameswater.co.uk.

17 Appendix.

Flow survey. We carried out a flow survey within our sewer network around the Ampney St Peter area, to help us to understand: • the volume of wastewater carried by the local sewers • how rainwater and groundwater getting into our sewer network affects its capacity and performance. As part of this survey we placed three rain gauges, six flow monitors and eight sewage pumping station monitors within Flow monitor the Ampney St Peter area. Figure 1 shows the coverage of Sewage pumping station monitor flow monitoring that took place across the area over a 50- day period, from February to March 2017.

For the duration of the flow survey we monitored local groundwater and river levels. To support this survey work, a resident of Ampney St Peter, Mr Michael Sharpe, kindly agreed to provide us with water level readings from a well on his property, as seen in Photo 1. The well readings were a further useful source for comparing local groundwater levels against the flows recorded in the Ampney St Peter village. Figure 1 Flow monitoring across the Ampney St Peter area. Unfortunately, groundwater levels were low during the time of the flow survey, particularly in comparison to the same period in previous years. Therefore, it wasn’t possible to monitor the influence of groundwater on the sewerage system as part of the flow survey.

Photo 1 Well in Ampney St Peter used for water level readings.

18 ‘Lift & Look’ and CCTV surveys. In December 2016 we did a ‘Lift & Look’ survey in Ampney Crucis and Ampney St Peter, and in January 2018 we carried out this survey in Poulton and Meysey Hampton.

The ‘Lift & Look’ surveys, together with the CCTV footage we recorded in 3,500 metres of our sewer network, found points where groundwater is entering our network through cracks and other defects. When we find groundwater entering our sewers we class it as a: seeper, runner or gusher, with a gusher being the most severe and creating the biggest problem for our network’s performance.

The main findings from the surveys include:

Ampney Crucis

In north west Ampney Crucis we observed groundwater runners entering our sewers from two pipes that connect properties to Figure 2 Locations where groundwater is the main sewer. The affected main sewer runs from manhole entering our sewer network in north west SP06028301 to SP06028203, as highlighted red in Figure 2. Ampney Crucis.

Reducing the amount of groundwater that enters the foul sewers in this area will help to increase capacity in the sewer network that runs from this location to Ford Farm (Ampney Crucis) sewage pumping station. Greater capacity in our sewers helps them to work properly and reduces the risk of flooding incidents for our local customers.

We propose to repair the damaged pipe causing the groundwater runner in north west Ampney Crucis, as a priority, and to reline all affected sewers in the future. This will reduce the amount of groundwater entering our sewer network in this area.

In east Ampney Crucis we found groundwater was flowing into our sewers at two locations. These areas are highlighted in red in Figure 3. Both locations were classed as runners – one from a pipe that connects to the main sewer near to manhole SP07026101, Figure 3 Locations where groundwater is entering and the other located in the sewer that runs from manhole our sewer network in east Ampney Crucis. SP07016903 to SP07016902.

We propose to investigate further the runner from the pipe into the main sewer, and also to carry out repairs to the defect in this sewer that was identified by our CCTV survey. 19 Ampney St Peter

In southern Ampney St Peter we found groundwater entering our sewer network at three locations. The affected sewers are highlighted in red in Figure 4. We found one runner within the main sewer and two within pipes that are connected to the main sewer.

We propose to investigate further the runners from the pipe into the main sewers, and also to carry out repairs to the defect in this sewer that was identified by our CCTV survey.

Figure 4 Locations where groundwater is entering our sewer network in southern Ampney St Peter. Poulton

In northern Poulton, we found unexpected levels of water in manhole SP10011102. This could potentially indicate that groundwater is entering our network from the sewers highlighted in red in Figure 5. We propose to jet-clean this length of sewer before using CCTV to pinpoint the exact locations where the groundwater is entering our sewer network.

We also propose to jet-clean the sewers highlighted red in Figure 6. We can then use CCTV to help us to identify where the unexpected Figure 5 Locations where groundwater is levels of flow is entering our sewer network, which we’ve found in potentially entering our sewer network in Poulton. manhole SP09018001. We’ll repair any sewer defects that we find as part of our survey work.

Figure 6 Locations where groundwater is potentially entering our sewer network in Poulton.

20 Meysey Hampton

In Greenacres Park Meysey Hampton we found groundwater entering our manhole identified in Figure 7 as MH3314A, and at the sewage pumping station represented as ‘PH10’ on the map. This sewage pumping station was previously in private ownership but, following a change in the law, we adopted it in 2016.

In Meysey Hampton we also found groundwater entering our manhole chamber identified as SU11999801 in Figure 8.

Reducing the number of locations where groundwater enters our Figure 7 Locations where groundwater is sewers in Meysey Hampton will help to increase capacity in the entering our sewer network in Meysey Hampton. sewer network to safely carry wastewater to the Meysey Hampton sewage pumping station. This will also reduce the amount of groundwater that is unnecessarily passed to the Ampney St Peter (Poulton) sewage pumping station, and Ampney St Peter sewage treatment works.

We’ll make sure that the sewage pumping station is repaired as a priority, and the defective manhole chambers, to reduce the amount of groundwater entering our sewer network in this area.

Figure 8 Location where groundwater is entering our sewer network in Meysey Hampton.

21 Impermeable area survey. Impermeable ground doesn’t allow rainwater to drain through it naturally such as driveways made out of concrete or tarmacadam, and roofs. Instead the rainwater from these areas pools together and often flows into our sewer network.

This additional water reduces the capacity of our sewers, stops them from working properly and contributes to the drainage issues in the local area. Our survey measured the size of the impermeable area in Poulton, and we investigated its impact on our sewer network.

Our survey in the Poulton area found:

Significant amounts of rainwater caught from the roofs of local properties flows into our sewer network, rather than draining away naturally. The total area of the roofs which incorrectly enter our sewers is the equivalent size of five tennis courts. This is highlighted in red in Figure 9.

We propose to investigate the possibility of removing roof drainage from our sewer network with Poulton Figure 9 Impermeable area survey findings summary. Parish Council. This could increase the capacity within our sewers and reduce the risk of flooding incidents for local residents in Poulton.

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x Flooding ‘trigger-levels’ analysis. We analysed the groundwater levels and river levels that were recorded during periods when there was flooding and other drainage issues in the area. We wanted to use this information to set up groundwater warning signs or ‘trigger levels’ so that we could investigate the impact this groundwater has on our sewers. We defined red and amber ‘trigger If an amber level is reached our local flood, to make sure our sewers have levels’, with red being the most critical team will check for unusually high a safe level of water in them, and we warning sign. A red ‘trigger level’ tells activity at our sewage pumping can reduce their risk of flooding. us that sewer flooding is very likely and stations. This could be a sign of that rapid action is needed to reduce groundwater entering our sewer the drainage issues. An amber ‘trigger network which shouldn’t be there. If level’ warns that sewer flooding is a red level is reached the team will possible. lift manhole covers in areas known to

Groundwater levels Vs Flooding incidents in Ampney St Peter 98 104 97.9 97.8 103.75 97.7 103.5 97.6 97.5 103.25 97.4 103 97.3 97.2 102.75 97.1 102.5 97 96.9 102.25 96.8 102 96.7 96.6 101.75 96.5 101.5 96.4 96.3 101.25 96.2 101 River level (mAOD) River level 96.1 100.75 96 Borehole level (mAOD) 59.9 100.5 59.8 100.25 59.7 Red trigger level 59.6 100 59.5 99.75 59.4 Amber trigger level 59.3 99.5 59.2 59.1 99.25 95 99

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River level average Ampney Crucis borehole Sewer network issue Figure 10 Flooding ‘trigger-level’ analysis for the Ampney St Peter area. Figure 10 is a graphical illustration of issues that have occurred in the weather patterns and groundwater our flooding ‘trigger-level’ analysis. Ampney St Peter area, particularly conditions. This will help us to plan The green line indicates the changing when the red ‘trigger-level’ threshold how we can further reduce sewer river level over time, the brown line level has been met, or exceeded. flooding and drainage issues for our shows the changing local groundwater customers in the Ampney St Peter level over time and the crosses identify We propose to continually check and area, now and in the future. when sewer network issues have refine our flooding ‘trigger levels’ to occurred in the Ampney St Peter area. improve their accuracy, particularly when ‘trigger levels’ have been Figure 10 demonstrates that there’s reached. Ongoing monitoring will a correlation between high river/ increase our understanding of how our groundwater levels and sewerage sewer network copes during different