East Hampshire River Basin Catchment

Our DWMP sets out our priorities for the East Hampshire River Basin Catchment. These include:

• Reducing the number of spills from the 93 storm overflows which together currently spill around 1,200 times per annum
• Separating or attenuating excess rainwater in the sewer networks to reduce the risks of flooding and frequency of storm overflow discharges, especially in Southsea, Bursledon, Denmead and Eastney
• Investigating the potential impact of wastewater discharges on Good Ecological Status in designated habitats including the Solent and Langstone Harbours
• Implementing measures to reduce nutrients in discharges at Budds Farm WTW
• Planning for potential significant developments at Portsmouth, Fareham, Tipner West, North Whiteley and Waterlooville
• Improving the resilience of our networks and treatment works to prevent pollution incidents, particularly in Gosport, Fareham, Burseldon, Drayton and Waterlooville
• Reducing the risk of sewer blockages by increasing sewer jetting and targeting customer campaigns to reduce the amount of FOG (fats, oils and grease) and non-flushables in the sewer network around Havant
• Reducing the risk to groundwater by reducing leakage from our sewers in the Havant, Horndean and Waterlooville areas.

Overview of the East Hampshire River Basin Catchment

We've worked with a wide range of organisations with responsibilities for drainage, flooding and protection of the environment while developing our DWMP. The organisations we worked with in the East Hampshire River Basin Catchment include:

• Hampshire County Council
• East Hampshire District Council
• Eastleigh Borough Council
• Fareham Borough Council
• Gosport Borough Council
• Havant Borough Council
• Portsmouth City Council
• The Environment Agency
• Natural England
• The East Hampshire Catchment Partnership and member organisations including:
• The South Downs National Park Authority
• The Hampshire and Isle of Wight Wildlife Trust
• The South East Wildlife Trust
• Groundwork
• Portsmouth University
• Solent Forum
• The Country Landowners Association
• Portsmouth Water

Working together to co-create the DWMP is important. Our drainage and wastewater systems are often interconnected with the systems managed and operated by others and affect the natural environments within the catchment.

A wide range of issues and concerns have been raised and discussed throughout the development of the DWMP for East Hampshire.

• The condition of the water environment around the Solent is a concern. There are important shellfish and recreational waters in coastal areas. There's a duty under the Habitat Regulations to demonstrate no significant effect on Special Protection Areas (SPAs). Peel Common discharges into Portsmouth Harbour SPA. Irrespective of the proportion of impact from wastewater treatment, all nutrient-related issues need to be addressed by working in partnerships with landowners, users and local authorities.
• There is high groundwater across the catchment. Coupled with surface water flowing into the sewers, this means there are a number of flooding hotspots in urban areas.
• Solutions to surface water runoff into the sewers such as diverting the flows into available watercourses, and potential locations for SuDS (Sustainable Drainage Systems) to slow the flow in urban areas must be found by working with others. Several possibilities have been highlighted including in Portsmouth, ‘green’ areas in Fareham and Gosport, and at the Rudmore motorway roundabout.
• Significant growth is required in Portsmouth around Fareham and north of the motorway. Portsmouth City Council is negotiating whether this can be absorbed by surrounding authorities. The capacity of the wastewater infrastructure needs to be reviewed in light of future schemes.
• Saline intrusion is already an issue in coastal areas and the risk and impact of sea level rise must be considered in future cycles of the DWMP.
• There is support for the water recycling scheme at Peel Common
• Both Budds Farm and Peel Common should be considered for a potential ‘change’ strategy in future DWMPs. Decentralisation are possibilities although all potential schemes must ensure the issues are not simply displaced elsewhere.

We're progressing these issues through the development of the DWMP as set out in our investment needs for East Hampshire. Furthermore, we commit to working with others to co-develop and co-deliver schemes that meet multi-organisational objectives and which benefit the environment, our customers and communities.

We developed and ran a series of activities between 2020 and 2022 as we prepared our DWMP for East Hampshire. You can see the dates and purpose of the various webinars, workshops, meetings on individual wastewater systems and interim consultation in the table below.

The regionally-based webinars presented and discussed issues and information relevant across the whole of our operating region.

You can view the presentations used in the webinars on our Who we’re working with page.

Workshop 1
Held in September 2020, participants discussed the findings of the risk based catchment screening and proposed additional planning objectives for the DWMP. Workshop slides.

Workshop 2
Held in April 2021, participants:

1. discussed the results from the BRAVA risk assessments and the proposed investment strategy for the wastewater catchments within the River Basin
2. identified the generic options that should be explored to address the identified risks, and
3. discussed which wastewater catchments to progress through the Options Development and Appraisal stage of the DWMP. Workshop slides.

Workshop 3
Held in March 2022, we reviewed and discussed the draft investment programme for the River Basin Catchment. This included the types of investment, priorities and timing for investment needs and the wider opportunities arising from the proposed investment in terms of partnership projects and catchment wide solutions providing multiple benefits. Workshop slides.

You can view the findings from our interim consultation.

Risk based catchment screening (RBCS) is a process that uses existing, readily available data. This is used to identify where there's a current and/or potential risk or vulnerability in the sewer catchment to future changes, such as new residential development or changes in climate. This enables effort to be focused on these catchments during the development of the DWMP in order to understand these risks in more detail and why they're likely to occur.

The RBCS involves the assessment of each sewer catchment against 17 indicators set out in guidance published by Water UK. Water companies can add additional indicators to ensure that other important issues are highlighted at this early stage in the development of the DWMPs. We've included an additional metric on customer complaints as this provides a flag for catchments with ongoing or outstanding concerns.

Find out more about the risk based catchment screening process.

The Baseline Risk and Vulnerability Assessment (BRAVA) is an important step in the development of our DWMP. This assessment helps us understand current system performance and future vulnerabilities. This means that we can identify the investment needed to manage and reduce the risks to band 0 (no significant level of risk).

A BRAVA assessment has been completed for each of the wastewater systems in the East Hampshire catchment that were flagged during the risk based catchment screening (RBCS). A risk assessment is completed for all 14 planning objectives.

The output of the BRAVA shows:

• the current risks and issues in each wastewater system within the East Hampshire Catchment. This provides a baseline from which we can assess future risks
• the future risks in 2030, 2035, 2045 and 2050 (where the methodology currently allows us to assess the future risks) so we can understand how the current risks may change without additional investment
• the key issues behind the future changes in risk, including:
• a deterioration in the condition of our wastewater systems
• climate change – including the increasing frequency and severity of droughts and storms
• growth and urban creep
• a combination of any or all of these that are relevant in the catchment being assessed.

You can download the results for the BRAVA for the East Hampshire River Basin Catchment below.

Download the BRAVA Summary for East Hampshire

Notes

1. In the BRAVA results table, “not flagged” means no risks were identified in the initial risk based catchment screening using the nationally set criteria. Wastewater systems not flagged were screened out and did not progress to the BRAVA stage. “Not applicable” means the planning objective was not relevant within the wastewater system. For example, where a system has no storm overflows, this will be marked as “Not applicable”.
2. Please check the DWMP glossary for any unexplained acronyms.

The Problem Characterisation stage of the DWMP uses the results from the Baseline Risk and Vulnerability Assessment (BRAVA) to explore the causes of risks and the primary drivers. A technical summary provides information on our approach to the Problem Characterisation stage.

Current risks in the East Hampshire Catchment

The graph below illustrates the combined results of the 2020 BRAVA assessment for all seven wastewater systems in the East Hampshire River Basin Catchment. It shows how many wastewater systems have a risk under each of the 14 planning objectives. For example, for the risk of internal flooding, four wastewater systems are in band 0 (not significant), two are in band 1, none are in band 2 (very significant) and one was ‘not flagged’ for inclusion (i.e. screened out at the risk based catchment screening stage of the DWMP).

The wastewater system with the highest number of planning objectives in band 2 (very significant) is Budds Farm. This system has six planning objectives in band 2. Peel Common has five planning objectives in band 2. All other catchments have fewer overall numbers of risks.

The specific risks and the causes of risk for each of the wastewater systems are explained in the summary of the problem characterisation for each system. These are available to download from the link next to the name of each system in the table below.

Future risks in the East Hampshire Catchment

The 2050 BRAVA results help us to identify the future challenges for drainage and wastewater management in the East Hampshire River Basin Catchment. These are:

(a) Growth

There are several wastewater catchments where new homes, businesses, roads and other infrastructure is planned. Local authorities across southern Hampshire have joined together as the Partnership for South Hampshire (PfSH) in a unique effort to map out the future of the region. The Partnership has a focus on four key areas of work, including housing. The Councils are co-operating on issues such as nutrient mitigation and strategic flood risk assessment.

The BRAVA results show that additional homes and businesses may increase the risks of non-compliance with our Dry Weather Flow (DWF) permits from the Environment Agency in two of the seven wastewater systems unless measures are taken. They are Peel Common and Bishops Waltham. This means further investment will be needed in the future to increase the capacity of our treatment works to accommodate the additional flows from new homes and businesses.

The additional development may mean that our current permits for wastewater treatment quality might be exceeded by 2050 without further investment in two of the wastewater systems, Bishop’s Waltham and East Meon. Peel Common is currently in band 2 for WTW compliance due to an incident in 2020 that disrupted the power supply for our ultraviolet (UV) treatment plant. This has since been rectified and the resilience of the UV plant has been improved.

Our risk assessment for nutrient neutrality has indicated that new development in the East Hampshire Catchment might put additional pressure on achieving favourable conditions of the internationally designated habitat sites in the Solent. The local councils are working with Natural England and the government to find suitable solutions to ensure that development is nutrient-neutral. This risk may require additional future investment in our wastewater treatment processes.

A map of the East Hampshire Catchment showing the estimated future growth in each wastewater system is shown below. The technical summary explains how we have considered population growth and urban creep in our DWMP.

(b) Climate change

Climate change will bring greater variability of our weather with warmer wetter winters and hotter drier summers. Due to this we could be seeing more intense summer storms that exceed the capacity of the drainage and wastewater networks and cause localised flooding. Hence, the risk of flooding from sewer systems is increasing due to climate change. The technical summary explains how we have considered climate change in our DWMP.

We're working with partner organisations, such as Hampshire County Council, District Councils and the Environment Agency, who have also responsibilities for flooding and drainage to consider options and develop opportunities to find solutions that reduce the risks from flooding.

We'll need to adapt our wastewater systems to operate in future climates. There will be an increasing need to slow the flow entering our sewer networks so the systems can carry the water without flooding homes and businesses and/or without causing discharges from storm overflows. Preventing additional rainfall from entering foul sewer networks, including combined sewer networks where possible, could delay the need to upgrade and enlarge the vast underground network of sewers.

Climate change is expected to have an impact on the risk of flooding in several wastewater systems, especially Budds Farm where there is already a very significant risk from rainfall-related flooding. The risk assessment for Wickham indicates that the flooding risks will increase from band 1 to band 2 by 2050 unless measures are taken.

Peel Common, Budds Farm, Southwick and Wickham systems all have storm overflows that discharge during periods of heavy rainfall. The risks from these discharges are currently very significant and climate change may increase the frequency of discharges unless measures are taken.

The map below shows the potential impact of climate change, urban creep and growth on the risk of flooding in a 1-in-20-year storm for the wastewater systems. We followed Water UK’s capacity assessment framework to apply a 20% uplift to rainfall forecasts to assess the potential increases in flood volumes shown on the map. Urban creep was estimated using the approach developed by the UK Water Industry Research (UKWIR) report on Urban Creep in sewerage systems (2010).

The map highlights that we'll need to adapt to climate change. Adaptation will mean considering long-term sustainable options, such as reducing the volume of rainwater entering the sewer network. This approach may provide the capacity within the wastewater system to allow for future growth and therefore reduce both the need for significant increases in the capacity of the existing wastewater systems and reduce discharges from storm overflows.

Investment planning for our wastewater systems

We used the BRAVA results and our understanding of the causes of risks and drivers to propose an investment strategy for each of the wastewater systems. Find out more information on how we determined the investment strategies. These strategies help us to target the wastewater systems that need further investment to reduce the potential risks to customers and the environment. We've produced a table that lists the proposed investment strategy for each catchment.

We used a risk-based approach to identify the wastewater systems that we need to progress in this first round of DWMPs. For these systems, we'll develop an investment plan. Our technical summary sets out how we selected the systems to take forward.

The table below lists the wastewater systems in the East Hampshire River Basin Catchment that we’re progressing further during this first round of the DWMPs into the investment planning stage. We've included a catchment map and an explanation of the causes of risks for these systems (see links in the table below).

The maps and causes of risks for the remaining wastewater systems in East Hampshire will be published when available.

Our approach to Options Development and Appraisal (ODA) is explained in a technical summary.

We commenced the ODA process at the river basin catchment (RBC) scale (level 2 planning). This enabled us to look across all the wastewater systems in the river basin and consider generic options that could work at the catchment scale, as well as those specific to a wastewater system.

The generic options are grouped into those that help tackle the risks ‘at source’, those that help to improve the wastewater system ‘the pathway’, and those that protect or mitigate the impacts on the receiving waterbodies, ‘the receptors’.

This process helped to identify the types of options that could be used individually or in combination with other options to address the risks.

We held meetings with partner organisations to build upon the list of generic options relevant to each wastewater system. As a group, we identified and proposed unconstrained options to tackle the drivers and causes of risks identified during the Problem Characterisation stage of the DWMP. We then progressed these unconstrained options through the Options Development and Appraisal stage.

The options appraisal involved evaluating each of the options in two stages. Firstly, to screen out unviable options to leave a set of ‘constrained’ options. Then, a second stage reduces the list further to leave only potentially ‘feasible’ options (see the Options Development and Appraisal technical summary for full details of this process). The process for evaluating the benefits and how we've taken the environment into account is set out in our Strategic Environmental Assessment (SEA) Scoping Report and the SEA Progress Report.

Only feasible options with positive benefits proceeded to the costing stage. This resulted in the selection of the preferred options and confirmed whether each was ‘least cost’ or provided ‘best value’.

The feasible options column in the table below shows how we applied the process within each wastewater system. Beginning with the generic options through the appraisal stages, the table shows the point at which some options were rejected and why. If an option wasn't rejected, it was costed and became either the final best value or the least cost preferred option (see ODA technical summary for details of this process).

Our final preferred options are set out in the Investment Needs tables for each wastewater system. The accompanying maps show the location of the proposed options within the wastewater system.

Please check the DWMP glossary for any unexplained acronyms.

The options and investment needs are not committed funding but an identification of the needs for funding. We'll include these options in our future business plans as part of the Ofwat periodic review of water company funding to secure the investment needed to implement these options.

The Programme Appraisal stage of the DWMP follows the Options Development and Appraisal (ODA) process. The ODA process identified the preferred options for investment in our wastewater systems to reduce the current risks as well as the risks up to 2050.

The Programme Appraisal brings the investment needs for each wastewater system together into an investment needs programme for the East Hampshire Catchment. We look across the river basin catchment to review the investments needed, the timing of these needs and how they combine to reduce the risks to our customers and the environment.

We also look at the wider risk reduction that each option provides across all the planning objectives. Some actions, like separating rainwater from wastewater sewers, could reduce risks under several planning objectives such as storm overflows, external flooding, bathing water quality, shellfish water quality and good ecological status. The details of the method for prioritisation can be found in our Technical Summary on Programme Appraisal.

The investment needs in the East Hampshire River Basin Catchment include:

• reducing the number of spills from the 93 storm overflows which together currently spill around 1,200 times per annum
• separating or attenuating excess rainwater in the sewer networks to reduce the risks of flooding and frequency of storm overflow discharges, especially in Southsea, Bursledon, Denmead and Eastney
• investigating the potential impact of wastewater discharges on Good Ecological Status in designated Habitats including the Solent and Langstone Harbours
• implementing measures to reduce nutrients in discharges at Budds Farm WTW
• planning for potential significant developments at Portsmouth, Fareham, Tipner West, North Whiteley and Waterlooville
• improving the resilience of our networks and treatment works to prevent pollution incidents, particularly in Gosport, Fareham, Burseldon, Drayton and Waterlooville
• reducing the risk of sewer blockages by increasing sewer jetting and targeting customer campaigns to reduce the amount of FOG (fats, oils and grease) and unflushables in the sewer network around Havant
• reducing the risk to groundwater by reducing leakage from our sewers in the Havant, Horndean and Waterlooville areas.

Investment Needs for the East Hampshire River Basin Catchment

We progressed two wastewater systems through the ODA stage in the first cycle of the DWMP. These two wastewater systems serve a population of around 622,000 which is approximately 97% of customers in this catchment.

We extrapolated the investment needs for these two systems to the other five systems in the East Hampshire River Basin Catchment. This provides an estimate of the total investment needs required to reduce the risks in all our wastewater systems in the catchment to band 0 (not significant). This concept of “Band Reduction” and full details of the process for extrapolation are explained in the Technical Summary on Programme Appraisal.

A graph to illustrate the extrapolation of investment needs across the whole river basin catchment is shown in figure 1.

Figure 1: East Hampshire: Extrapolated Investment Needs and Risk Band Reduction

The Programme Appraisal for East Hampshire identified the following needs.

• A total of 33 band reductions are required in 2020 to reduce the risks across the 14 planning objectives in the two wastewater systems.
• By 2050, this requirement will stay the same at 33 band reductions even taking climate change, growth and creep into account. Although the risks will increase, this is not visible where the risk is already in the highest risk band 2.
• The options identified to date would cost around £780 million for the two systems and are expected to provide 22 Band Reductions in 2050 (the identified options do not result in a band 0 for all risks).
• East Hampshire consists of seven wastewater systems, which require 49 band reductions in 2020 and 54 band reductions by 2050 in order to achieve band 0 across 14 planning objectives.
• Extrapolating the investment needs for all the systems in East Hampshire will cost around £1.64 billion for a population of 640,000. This illustrates the scale of investment needed to get to band 0 by 2050 for all 14 planning objectives.

These investment needs provide indicative costs that allow us to understand the level of funding required to reduce the risks. The funding hasn't been secured at this stage. The DWMP informs the development of our 5 yearly Business Plan which is submitted to our economic regulator, Ofwat, to agree on how we should invest the money received from our customer bills.

Consultation on the East Hampshire River Basin Catchment

We held an initial consultation on our draft DWMP in September and October 2021. The purpose of the consultation was to gain feedback and advice from our customers and organisations on our developing Plan. We specifically asked about:

• our Strategic Environmental Assessment Scoping Report
• our selection of wastewater systems to take forward into the Options Development and Appraisal stage of the DWMP in the first cycle, and
• our developing plans on each of the 11 river basin catchments.

Our report on the initial DWMP consultation is now available.

When we consulted on the developing plans for the East Hampshire River Basin Catchment you highlighted key issues for us to take into consideration.

• Storm overflows and discharges to the Solent and Harbours need to be reduced and effluent treatment upgraded to improve water quality and return these habitats to favourable status. Water effluent treatment should remove plastics and agents harmful to wildlife.
• The investment strategy for both Peel Common and Budds Farm should be changed from ‘improve’ to ‘change’. Both have an extremely high number of significant risks, the growth projections are high and the impact on the environment is serious.
• Wider issues need to be considered such as economic and social issues and protecting the natural environment.
• The DWMP needs to align with other environmental strategies so that the time and funding of external organisations and local community buy-in are also aligned. This is essential to tackle issues such as water use, winter water storage, nature corridors, FOG, hard landscaping and misconnections.
• Funding for a dedicated enforcement officer should be considered.

How we responded to the issues raised during the workshops and the preliminary public consultation is set out in our Register of Stakeholder Comments.

We held a full 12-week public consultation on the draft Regional (Level 1) DWMP between Monday 13 June and Monday 05 September 2022. Our Statement of Response and a report and analysis on the consultation is published on the Have your say page.