Milton Keynes Water Cycle Study Outline Strategy

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Final December 2008

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Milton Keynes Council Water Cycle Study – Outline Strategy

Revision Schedule

Milton Keynes Water Cycle Study – Outline Strategy December 2008

Rev Date Details Prepared by Reviewed by Approved by

01 23rd May 2008 Interim Draft Gemma Costin Carl Pelling David Dales Assistant Consultant Senior Consultant Director

Andrew Woodliffe Senior Consultant

02 22nd July 2008 Final Draft Gemma Costin Dr Jon Hillman David Dales Assistant Consultant Senior Consultant Director

Andrew Woodliffe Senior Consultant

03 26th September Final Draft v2 Gemma Costin Andrew Woodliffe David Dales 2008 Assistant Consultant Senior Consultant Director

04 19th December Final Gemma Costin Andrew Woodliffe David Dales 2008 Assistant Consultant Senior Consultant Director

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Milton Keynes Council Water Cycle Study – Outline Strategy

Table of Contents

Table of Contents...... i Executive Summary ...... iv Acronyms...... viii 1 Introduction ...... 1 1.1 Growth in Milton Keynes...... 1 1.2 Development and the Water Cycle ...... 2 1.3 Milton Keynes WCS and the Planning Process...... 3 2 Milton Keynes Water Cycle Strategy ...... 6 2.1 Approach to the Water Cycle Strategy...... 6 2.2 WCS Stakeholders ...... 8 3 Milton Keynes Growth Context ...... 13 3.1 New Housing Areas...... 13 3.2 New Employment Areas ...... 18 4 WCS Methodology ...... 19 4.1 Step 1a / Step 1b: Baseline Conditions and Capacity ...... 19 4.2 Step 2: Water Services Infrastructure Development Options ...... 21 4.3 Data Limitations...... 22 5 Flood Risk Baseline...... 23 5.1 Flood Risk Identification Methodology...... 23 5.2 Available data and Assumptions...... 24 5.3 Baseline Description...... 24 5.4 Fluvial...... 26 5.5 Sewers ...... 30 5.6 Surface Water...... 32 5.7 Groundwater...... 35 5.8 Artificial Sources...... 36 5.9 Flood Risk Constraints Summary...... 37 5.10 Data Limitations...... 39 6 Wastewater Baseline and Capacity ...... 41 6.1 Available Data and Assumptions ...... 42 6.2 Wastewater Treatment Baseline and Capacity ...... 43

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6.3 Wastewater Network Baseline and Capacity...... 45 6.4 Wastewater Environment Baseline ...... 50 6.5 Water Quality Baseline and Capacity...... 51 6.6 Wastewater Summary ...... 59 7 Water Resources and Supply Baseline ...... 61 7.1 Introduction...... 61 7.2 Available Data and Assumptions ...... 61 7.3 Regional Water Resources: Existing Situation...... 61 7.4 Milton Keynes - Water Resource Baseline Assessment...... 62 7.5 Water Supply – Existing Capacity ...... 65 7.6 Water Supply Network – Baseline...... 73 7.7 Bedford and Milton Keynes Waterway ...... 75 7.8 Water Resources and Water Supply Summary...... 76 8 Water Cycle Option Development ...... 78 8.1 Introduction...... 78 8.2 Wastewater Option Development ...... 78 8.3 Water Resources Option Development...... 79 9 Generation of Flood Risk - SUDS Options...... 86 9.1 Introduction...... 86 9.2 Flood Risk from Development – Strategic Options...... 86 9.3 SUDS Utilisation ...... 89 9.4 Flood Risk Management Summary...... 96 10 Ecological Assessment...... 97 10.1 Objectives and Approach...... 97 10.2 Sites within Milton Keynes Unitary Authority ...... 101 10.3 Sites of Special Scientific Interest ...... 101 10.4 Local Nature Reserves ...... 101 10.5 Downstream Sites - Special Areas of Conservation...... 102 10.6 Downstream Sites - Special Protection Areas...... 105 10.7 Ramsar Sites...... 106 10.8 Sites of Special Scientific Interest ...... 108 10.9 Overall Screening Opinion...... 109 11 Water Quality / Water Framework Directive...... 112 11.1 Water Framework Directive Standards ...... 113 11.2 WFD and Milton Keynes ...... 118

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11.3 WFD and Water Company Planning ...... 124 12 Development Area Assessment ...... 126 12.1 Central Area ...... 127 12.2 Eastern Area...... 129 12.3 Western Area...... 131 12.4 Northern Area...... 133 12.5 South Western Area ...... 135 12.6 Land East of the M1...... 137 12.7 Rural Areas...... 139 13 Water Efficiency ...... 142 13.1 New Development – Water Efficiency...... 142 13.2 Code for Sustainable Homes ...... 142 13.3 Current Development – Reducing Existing Baseline...... 144 14 Policy, Developer Guidance and Funding...... 145 14.1 Introduction...... 145 14.2 Developer Checklist...... 146 14.3 Funding and Cost Apportionment Mechanisms...... 146 15 Conclusions and Recommendations ...... 150 15.1 Overview ...... 150 15.2 Flood Risk and Drainage ...... 150 15.3 Water Environment...... 151 15.4 Wastewater Treatment and Transmission...... 153 15.5 Water Resources and Water Supply...... 154 15.6 Milton Keynes Tariff System ...... 155 15.7 Scope for Detailed WCS (REMOVE) ...... Error! Bookmark not defined. 16 References...... 156 Appendix A – Data Requests ...... 158 Appendix B – Wastewater Network Capacity Calculations ...... 159 Appendix C – DWF Calculations ...... 160 Appendix D – Hydrological Analysis...... 161 Appendix E – SUDS Options Details...... 162 Appendix F – Developer Checklist ...... 165

Final December 2008 iii Milton Keynes Council Water Cycle Study – Outline Strategy

Executive Summary

Study Purpose This Outline Stage 1 Water Cycle Study has assessed the impact of proposed growth targets for Milton Keynes (as set out in the RSS) on the water cycle infrastructure and water environment of the Milton Keynes study area. This has been undertaken for an approximate total of 57,950 new homes up to 2031.

It has been developed to inform and provide an evidence base to the initial stages of the production of Milton Keynes Council’s Local Development Framework (LDF). It is also required to provide justification for the planning of new infrastructure in Anglian Water Service’s strategic business planning; and to provide the Environment Agency (EA) and Natural England (NE) with a strategic study that identifies and suggests mitigation for potential water environment impacts (including flood risk) such that sustainable development is proposed in Milton Keynes and that objections to proposed developments in Milton Keynes are minimised.

The Outline Milton Keynes WCS has identified the existing capacity of the current water environment and water cycle infrastructure and has used this assessment to determine where additional investment is required to supply new infrastructure or to protect the water environment. Wastewater Discharge Capacity and Water Environment Increased effluent discharges to the River Ouzel and River Great Ouse will impact on flood risk and water quality. Before approving increases in consented discharges to these rivers, the EA will require further catchment modelling to identify any necessary mitigation works particularly with reference to the lakes in Milton Keynes. This should either be included in the detailed stage of the water cycle study, the level 2 SFRA or as an independent study for example a surface water management plan.

For water quality, the EA position has been that any increase in flows from WwTWs that occur as a result of growth must comply with their policy on ‘No Deterioration’. This requires that increases in failure of a mandatory standard caused by growth should be offset by reducing the consent limits of the associated discharge(s). The policy allows the EA to impose consent limits up to the limit of technological capabilities (Best Available Technology Not Entailing Excessive Cost - BATNEEC). It also allows the EA to make special justification for imposing consent limits more stringent than BATNEEC.

Increase in Dry Weather Flow (DWF) equates to 8% of consented discharge from Cotton Valley is forecast to be required during the planning period (to 2031). This will require an Appropriate Assessment of impact on designated sites downstream. The detailed water cycle study will need to collect sufficient data to allow

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the EA/Natural England to complete an AA. This should build on the assessments completed for Phosphorous Wastewater Treatment and Wastewater Network Capacity There is sufficient capacity to accommodate short and medium term growth in all of the non rural expansion areas in terms of wastewater treatment.

To accommodate the significant growth to the east (between Wavendon and Cotton Valley), upgrades to the Broughton Brook trunk sewer are required. The ongoing work to increase the capacity of the inlet works at Cotton Valley WwTW is expected to greatly increase the effective capacity of this trunk sewer and other parts of the network. To serve the Western expansion, a combination of new pumping stations and sewers is required to connect to the existing network. Capacity issues at Newport Pagnell and the disruption and cost of upgrading the existing sewer to Cotton Valley mean that the proposed site east of M1 motorway would need to be served by a new connection to this works. The south-west development area can be served with little infrastructure upgrade required to transfer to the point of connection to existing system. In central Milton Keynes, some infrastructure upgrades are expected to be required particularly in the Oakgrove area.

Some strategic scale investment will be required for medium and long term development in terms of wastewater network infrastructure in order to service the new development particularly within the western expansion area, eastern expansion and for land to the east of the M1.

In the long-term, (2020-2031) flow consent at Cotton Valley and extension of the treatment works will be required. Water Resources and Supply Capacity This study has shown that in the short-medium term there are sufficient water resources and supply capacity for the development proposed for Milton Keynes. However, in the longer term (2019/20 and beyond) it may be necessary for a major regional water resource development such as the Trent Transfer scheme to ensure there is sufficient supply to service the development in Milton Keynes.

Currently Milton Keynes receives most of its water from Wing and Grafham WTWs, which are in turn fed from Rutland Water and Grafham Water respectively. Work is currently being undertaken at Wing WTW which will ease the situation in the short term. In order to maintain sufficient gap between supply and demand, it will be necessary to supplement available resources by the development of local schemes, such as Foxcote WTW (a surface water intake and reservoir), within the existing abstraction licence limits. In addition, phased developments at Clapham WTW will release Deployable Output from Grafham to

Final December 2008 v Milton Keynes Council Water Cycle Study – Outline Strategy

supply the growth in Milton Keynes, although this may also require an increase in the abstraction licence at Clapham (on the River Bedford Great Ouse).

The extent of the development proposed for Milton Keynes will also require stringent water efficiency measures to put in place on all new homes, these measures should be in-line with the current best practice in this area e.g. Code for Sustainable Homes (April 2008).

At this high level, there are a number of uncertainties which have the potential to adversely impact supply. These include the impacts of climate change, the Review of Consents and legislation associated with the Water Framework Directive (WFD).

It is essential that water supply network modelling and modelling of the capacity of the water treatment works supplying Milton Keynes is undertaken as part of the detailed WCS. Flood Risk and Drainage There are several Main River 1, IDB managed and Ordinary Watercourses that run through the study area. All of these watercourses have Flood Zones and hence flood risk associated with them. The main watercourses in the study area are the River Great Ouse to the north of the study area, the River Ouzel to the east of the study area, Chicheley Brook and Broughton Brook to the east of the study area, Water Eaton Brook to the south of the study area and Loughton Brook to the west of the study area.

Instances of fluvial, surface water and sewer flooding have been recorded in the study area, and future development has the potential to increase the frequency and consequence of such flooding through the increases in and runoff from impermeable areas. These increases can be mitigated through the use of integrated SUDS, careful development design, development control and masterplanning. Milton Keynes has a network of green infrastructure which will be maintained and enhanced through development design.

Groundwater flooding has not been recorded in the study area but there are however areas of more permeable geology to the south east of the area, near Woburn Sands where there is a potential risk of such flooding.

The Grand Union Canal also runs through the study area and carries with it an inherent flood risk. Broad Expansion Area Assessments An assessment has been undertaken of the seven potential expansion areas to demonstrate how development could impact upon the water environment, wastewater treatment and network capacity, water supply, and flood risk.

1All watercourses shown as such on the statutory main river maps held by the Environment Agency and the Department of Environment, Food and Rural Affairs, and can include any structure or appliance for controlling or regulating the flow of water into, in or out of the channel. The Environment Agency has permissive powers to carry out works of maintenance and improvement on these rivers

Final December 2008 vi Milton Keynes Council Water Cycle Study – Outline Strategy

These broad scale assessments have shown that in the short and medium term (to 2021), with the exception of certain sewer network issues, there are no major constraints to development within Milton Keynes. At this stage, there are however a number of unknowns and some key assumptions, particularly with regards to wastewater and network capacity have been made. It is vital that these uncertainties are considered thoroughly as part of the next detailed stage WCS. It has also not been possible to rule out adverse impacts upon the designated sites that are situated within and downstream of the study area, and it may be that these become significant constraints following a detailed assessment.

Final December 2008 vii Milton Keynes Council Water Cycle Study – Outline Strategy

Acronyms

Abbreviation Description

AMP Asset Management Plan

AWS Anglian Water Services

BAT Best Available Technology

BATNEEC Best Available Technology Not Entailing Excessive Cost

BOD Biochemical Oxygen Demand

CAMS Catchment Abstraction Management Strategy

CFMP Catchment Flood Management Plan

CSH Code for Sustainable Homes

CSO Combined Sewer Overflow

CLG Communities and Local Government

DEFRA Department for Environment, Food and Rural Affairs

DO Dissolved Oxygen/Deployable Output

DPD Development Plan Document

DWF Dry Weather Flow

EA Environment Agency

EP English Partnerships

FtFT Flow to Full Treatment

GI Green Infrastructure

GQA General Quality Assessment

HPPE High Performance Poly Ethylene (pipe)

IDB Internal Drainage Board

l/c.d Litres per capita per day (water consumption measurement)

LDF Local Development Framework

LiDAR Light Detection and Ranging

LPA Local Planning Authority

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Abbreviation Description

MBR Membrane Bioreactor

MKC Milton Keynes Council

MKP Milton Keynes Partnership

MKWCS Milton Keynes Water Cycle Strategy

N Nitrogen

NGP New Growth Point

NE Natural England

NVZ Nitrate Vulnerable Zone

OFWAT The Office of Water Services

P Phosphorous

PE Population Equivalent

PPS Planning Policy Statement

RSS Regional Spatial Strategy

SA Sustainability Appraisal

SAC Special Area for Conservation

SEA Strategic Environmental Assessment

SEP South East Plan

SfG Strategy for Growth

SFRA Strategic Flood Risk Assessment

SIMCAT EA mathematical River Water Quality Model

SPA Special Protection Area

SPZ Source Protection Zone

SRP Soluble Reactive Phosphorus

SSSI Site of Special Scientific Interest

SWMP Surface Water Management Plan

SUDS Sustainable Drainage Systems

TSFR Treated Sewage Flow Recorder (flow meter)

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Abbreviation Description

TSS Total Suspended Solids (in waste water)

UWWTD Urban Wastewater Treatment Directive

WCS Water Cycle Strategy/Water Cycle Study

WFD Water Framework Directive

WRMP Water Resources Management Plan

WRPZ Water Resources Planning Zone

WRZ Water Resources Zone

WSI Water Services Infrastructure

WwTW Waste Water Treatment Works

Final December 2008 x Milton Keynes Council Water Cycle Study – Outline Strategy

1 Introduction

1.1 Growth in Milton Keynes

Milton Keynes is located in southeast England, bordering the administrative districts of Aylesbury Vale (South East Region) Bedford Borough, Mid Bedfordshire, South Bedfordshire (East of England Region) Wellingborough and South Northamptonshire (East Midlands Region). Milton Keynes is one of the fastest growing urban centres both in the sub-region and the country and it is a significant employment centre for the sub-region. It is also a significant retail, service and administrative centre for the sub region. The Milton Keynes city limits are located to the south of the confluence of two rivers, the River Great Ouse and the River Ouzel and are surrounded by several environmentally and ecologically important designated sites including four Sites of Special Scientific Interest (SSSI) and several county wildlife sites.

The housing growth targets for Milton Keynes up to 2026 are set out in the draft South East Plan (SEP) 2 and have been augmented in this WCS with figures from the Milton Keynes Council (MKC) Local Development Framework (LDF) and Strategy for Growth to 2031. A substantial amount of the proposed growth to 2026 is allocated in seven broad expansion areas (north, rural areas, central area, east, west, south-west and land east of the M1), two of which (south east and south west) extend into the administrative areas of the neighbouring authorities of Mid Bedfordshire and Aylesbury Vale.

Water Cycle Studies (WCS) are required to ensure that proposed growth does not adversely impact on the existing water cycle environment and that new Water Services Infrastructure (WSI) can be planned for and provided alongside new development in a sustainable and cost effective manner. Due to the scale of development proposed for Milton Keynes, it is considered that a WCS is required to ensure that the proposed growth targets can be met without adversely impacting on the water environment and that required infrastructure can be planned for and brought online alongside new development, in a timely and phased manner.

2 All references to the draft South East Plan include the Panel Report from the Public Examination, which sets out a revised set of housing and employment targets, spatial distribution and phasing. The Panel Report figures are the ones used in this WCS and will need to be reconsidered once the South East Plan is finally adopted.

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1.2 Development and the Water Cycle

1.2.1 What is the ‘Water Cycle’?

In its simplest form, the Water Cycle can be defined as ‘the process by which water is continually recycling between the earth’s surface and the atmosphere’. Without considering anthropogenic influences, it is simply the process by which rain falls, and either flows over the earth’s surface or is stored (as groundwater, ice or lakes) and is then returned to the atmosphere (via evaporation from the sea, the soil, surface water or animal and plant life) ready for the whole process to repeat again.

In the context of this study, the ‘water cycle’ has a broader definition than the simple water or ‘hydrological cycle’. The human influence on the water cycle introduces many new factors into the cycle through the need to abstract water from the natural environment, use it for numerous purposes and then return to the natural system. The development and introduction of technology such as pipes, pumps, drains, and chemical treatment processes has meant that human development has been able to manipulate the natural water cycle to suit its needs and to facilitate growth and development. ‘Water Cycle’ in this context is therefore defined as both the natural and engineered water related environment (such as rivers, wetland ecosystems, aquifers etc), and the WSI (hard engineering focused elements such as: water treatment works, supply pipelines and pumping stations) which are used by human activity to manipulate the system.

1.2.2 The Problem

In directly manipulating elements of the water cycle, man affects many changes to the natural water cycle which can often be negative. To facilitate growth and development, there is a requirement for clean water supply which is taken from natural sources (often depleting groundwater stores or surface systems); the treatment of waste water which has to be returned to the system (affecting the quality of receiving waters); and the alteration and management of natural surface water flow paths which has implications for flood risk. These impacts can indirectly affect ecology, which can be dependent on the natural features of a water cycle.

1.2.3 Implications for Development: The Solution

In many parts of the UK, some elements of the natural water cycle are considered to be at, or close to their limit in terms of how much more they can be manipulated. This is especially relevant for the south and east of England where rainfall and hence available water for supply is the lowest in the UK. Further development will lead to an increase in demand for water supply and a commensurate increase in the requirement for waste water treatment; in addition, flood risk may increase if development is not identified

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and planned for in a strategic manner. The sustainability of the natural elements of the water cycle is therefore at risk.

A WCS is an ideal solution to address this problem. It will ensure that the sustainability of new development is considered with respect to the water cycle, and that new WSI introduced to facilitate growth is identified and planned for in a strategic manner. In so doing, the WCS can ensure that provision of water WSI is sufficient such that it maintains a sustainable level of manipulation of the natural water cycle, drawing upon the Strategic Flood Risk Assessment (SFRA) to facilitate flood risk mitigation, and to highlight areas where a Surface Water Management Plan (SWMP) may be required. A twin-track approach and behavioural change will be required to achieve the high levels of water efficiency required to ensure this sustainable manipulation of the water cycle is adhered to.

1.3 Milton Keynes WCS and the Planning Process

The Department for Communities and Local Government (CLG) are responsible for managing Local Government and as such, the associated planning guidance. A Local Development Framework (LDF) is the spatial planning strategy introduced in England and Wales by the Planning and Compulsory Purchase Act 2004 and given in detail in Planning Policy Statement (PPS) 12. The LDF and its associated Local Development Documents (LDDs) will replace the previous Local Plan documents produced by Local Planning Authorities (LPA) and will set out how the growth within each LPAs administrative area will be achieved. It should be noted that the WCS is an iterative process, as it evolves it will require continual monitoring and review and be periodically updated.

As part of the LDF process, LPAs are required to produce evidence based studies which support the selection processes used in deciding on final growth targets and areas to be promoted for growth. The WCS is one such example of an evidence-based study which specifically addresses the impact of proposed growth on the ‘water cycle’ and as such, will form an important component of the emerging MKC LDF. Specifically the WCS will sit alongside the Sustainability Appraisal (SA), Strategic Environmental Assessment (SEA) and Appropriate Assessment (AA), where necessary, forming a key evidential document in the LDF portfolio. The WCS builds upon other key flood risk work carried out, including the Milton Keynes Drainage Strategy (Halcrow 2004) which has been adopted as Supplementary Planning Guidance (SPG). The WCS will also inform the emerging MKC Core Strategy Development Plan Document (DPD), the key strategic policy document in the emerging LDF.

WCS’s are a relatively new approach to assessing the impact of new development with respect to the water cycle; however, the Milton Keynes WCS must be sufficiently robust such that it can form part of the evidence base for the emerging LDF.

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1.3.1 WCS Links with other LDF Studies

There are several other studies which have been, or are in the process of being produced on behalf of MKC to act as evidence bases to the developing LDF. Those most relevant to the WCS are listed below and it is intended that the developing WCS will both inform and be informed by these studies:

• A Strategy for Growth to 2031 (SfG),

• Green Infrastructure Plan (GI),

• Strategic Flood Risk Assessment (SFRA),

Strategy for Growth to 2031

The overall aim of the SfG was to identify options for, and make a recommendation on, the optimal directions for strategic growth, determine the implications of that growth in relation to infrastructure both physical and social, and identify mechanisms and ways to deliver, manage and monitor that change. The study is another key piece of the evidence base and has been used specifically to define the potential development area options for the Core Strategy, to be assessed in this WCS.

Green Infrastructure Plan

The purpose of linking with the GI Plan has been to consider the potential for the water cycle elements of the proposed development areas to be linked to Milton Keynes’ green corridors and infrastructure. This is to ensure an appropriately resourced and managed network of accessible, sustainable and linked open spaces for current and future generations, taking into consideration the large-scale growth proposed for Milton Keynes. The key aim of the GI Plan is to make recommendations such that the future urban extensions are to be developed sustainability, with green space and environmental assets to be protected and enhanced and planned for from the outset.

Strategic Flood Risk Assessment

The Level 1 SFRA undertakes a strategic (district wide) assessment of the sources of flood risk in the MKC administrative area and considers implications of flood risk arising from new development.

The Level 1 SFRA allows MKC to undertake Sequential Testing on any proposed or likely future potential development areas, as required in Planning Policy Statement 25 (PPS25: Development and Flood Risk). Sequential Testing is a method by which development areas are considered and selected on the basis of taking forward the areas with lowest flood risk, unless there are overriding sustainability reasons for considering higher risk options.

Where overriding factors prevail, a Level 2 SFRA assessment is required. A Level 2 assessment would provide MKC with the evidence base required to undertake Exception Testing.

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Preliminary outputs from the Level 1 SFRA have been used in the WCS to determine the level of flood risk to potential development sites in Milton Keynes, but also the potential flood risk that might arise as a result of development in Milton Keynes.

1.3.2 Aim of the Milton Keynes WCS

In conjunction with the other strategic studies which inform the LDF, a WCS for Milton Keynes is therefore required to:

• Ensure a co-ordinated approach to identify water supply and waste water infrastructure to support development,

• Avoid negative impact on water-dependent European sites of nature conservation and non European designated sites,

• Assess the requirement for flood risk mitigation and identification of where Surface Water Management Plans (SWMP) may be required,

• Identifying environmental and ecological constraints and maximising ecological opportunities and enhancements,

• Provide an evidence base for LDDs to site development so that MKC can:

• Ensure delivery of new development in Milton Keynes in the most sustainable way with respect to the water cycle environment,

• Maximise potential of existing WSI,

• Minimise need for new WSI.

The purpose of this report is to summarise the outputs of the Stage 1 Outline WCS undertaken for Milton Keynes in light of the required housing and employment growth targets, as set out in the draft Regional Spatial Strategy (RSS9).

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2 Milton Keynes Water Cycle Strategy

2.1 Approach to the Water Cycle Strategy

The Milton Keynes WCS intends to test the suitability of the proposed development area options and development scenarios for Milton Keynes taking into account existing and new WSI, whilst considering the impacts of proposed growth to the receiving water cycle environment.

2.1.1 Stages of a Water Cycle Strategy

In general, there are three main stages in undertaking and producing a WCS (Figure 2-1).

Figure 2-1:Stages of a Water Cycle Strategy Source: http://www.environment-agency.gov.uk/commondata/acrobat/water_cycle__1760254.pdf

The first stage of the Milton Keynes WCS was commissioned by the EA and the ‘Scoping Study’ undertaken by Halcrow.

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This information has been used to inform this report, which forms the ‘ Outline Study’ . The Outline Study will work alongside MKCs developing Core Strategy, and assist in providing a robust evidence base for MKCs emerging LDF. For Milton Keynes, the Outline Study must assess and identify:

• Any absolute water cycle environmental capacity constraints to development,

• Any WSI constraints to development,

• Whether any new WSI is required and hence must be planned for to facilitate new development and which strategic level options are available for delivering new infrastructure required,

• The most suitable (and sustainable) development areas and/or development scenarios with respect to the water cycle.

The Outline Study will also provide the necessary evidence base for the water company as part of the AMP process.

The final stage of the WCS is the ‘Detailed Study’ which will work alongside the latter stages of the LDF process, taking into account other planning considerations as part of this process. The overall aim is to lead to a water cycle strategy for Milton Keynes which:

• Identifies what WSI is required for Milton Keynes and where it is needed,

• Identifies who is responsible for providing and maintaining the infrastructure and when it has to be provided by,

• Provides details regarding funding requirements, e.g. developer contributions and other potential sources,

• Provides guidance for MKC and potential developers on site specific infrastructure requirements (e.g. strategic and integrated SUDS).

Following completion of the Outline Study, the Detailed Study for Milton Keynes will be undertaken once the development scenarios have been agreed with respect to all other planning considerations which must be taken into account.

For the purposes of this report, the acronym WCS has been used to refer to both the Water Cycle Study , the outline stage of which this report forms, and the all encompassing three stage Water Cycle Strategy .

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2.1.2 Development Definition

In the context of this Outline Study and due to the proposed volume of development within Milton Keynes, ‘broad’ areas have been determined in conjunction with MKC and the Milton Keynes Partnership (MKP). It is these ‘broad’ areas which are identified for constraints and risk with respect to the water cycle environment and WSI, as well as the requirement for new infrastructure required to facilitate development.

However, it is recognised that development can be brought forward in a number of ways according to associated site constraints and risks. It is also recognised that these constraints and risks also apply to other planning aspects of future development being considered by MKP and MKC (i.e. transport links, hospitals and health care and schools). As such, when considering the water cycle and water environment in isolation through this study, there is a requirement to consider a range of options for meeting housing and employment targets.

This outline WCS achieves this by identifying incremental potential development scenarios within smaller study areas and assessing the subsequent sustainability for each of the incremental potential development scenarios with respect to the water cycle. In so doing, this outline WCS allows MKP and MKC to consider the relative importance of water cycle issues alongside other planning considerations when making final decisions on allocations and development promoted in the Core Strategy.

2.1.3 Development in Milton Keynes

The broad development areas identified for Milton Keynes (in the SfG, the draft RSS 9 and the Core Strategy Preferred Options), are within and adjacent to the existing urban extent of Milton Keynes. However, growth is also shown to push out into the fringes of Mid Bedfordshire and Aylesbury Vale (although these growth directions have yet to be agreed, as the growth targets set out in the draft RSS9 have yet to be finalised).

In addition to the proposed development within the ‘broad’ development areas, the additional WSI required for growth has the potential to impact on a wider area associated with the protected areas of high ecological value and biodiversity

2.2 WCS Stakeholders

The outline WCS is being undertaken on behalf of MKC, MKP and the Environment Agency (EA). The study has been overseen by a Project Steering Group chaired by MKC, and made up of representatives from other organisations, all of which have a vested interest in future development in Milton Keynes and/or its impact on WSI and environment. The following parties made up the Project Steering Group:

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• Milton Keynes Council (MKC),

• Milton Keynes Partnership (MKP),

• Environment Agency (EA),

• MK Parks Trust,

• Aylesbury Vale District Council (AVDC),

• Anglian Water Services Ltd (AWS),

• English Partnerships (EP),

• Buckingham and River Ouzel Internal Drainage Board (IDB),

• Scott Wilson (SW).

2.2.1 Integration with the Planning System

It is important at this stage to consider the planning timelines, both for MKC in terms of the LDF but also AWS in terms of the funding mechanisms for new water supply and water treatment infrastructure.

2.2.2 Local Authority Planning

The production of the LDF involves an extensive process of consultation with the wider public and for Development Plan Documents like the Core Strategy, public examination for CLG. This overall planning process supports a two stage strategy for the water cycle study so that important considerations are not overlooked in-between the production of an outline study (which informs the Core Strategy) and the detailed study (which will be used in site or topic specific Local Development Documents). The detailed WCS will also make recommendations on phasing for development based on the water cycle issues.

2.2.3 Water Company Planning

There are two elements of Water Company planning that are pertinent to the Milton Keynes WCS and specifically, with regard to integration with Spatial Planning timelines for LPAs and Regional Government.

Financial and Asset Planning

Water Companies currently plan for Asset Management and the financial procurement required for this through the Asset Management Plan (AMP) process which runs in 5 year cycles. The Office of Water Services (OFWAT) is the economic regulator of the water and sewerage industry in England and Wales, and regulates this overall process.

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In order to undertake maintenance of its existing assets and to enable the building of new assets (asset investment), Water Companies seek funding by charging customers according to the level of investment they need to make. The process of determining how much asset investment required is undertaken in conjunction with: the EA as the regulator determining investment required to improve the environment; the Drinking Water Inspectorate (DWI) who determine where investment is required to improve quality of drinking water; and OFWAT, who along with the EA require Water Companies to plan sufficiently to ensure security of supply (of potable water) to customers during dry and normal years. The outcome is a Business Plan which is produced by each Water Company setting out the required asset investment over the next 5 year period, the justification for it and the price increases required to fund it.

Overall, the determination of how much Water Companies can charge its customers is undertaken by OFWAT. OFWAT will consider the views of the Water Company, the other regulators (EA and DWI) and consumer groups such as the Consumer Council for Water when determining the price limits it will allow a Water Company to set in order to enable future asset investment. This process is known as the Price Review (PR) and is undertaken in 5 year cycles. When OFWAT make a determination on a Water Company’s business plan, the price limits are set for the proceeding five year period allowing the water company to raise the funds required to undertake the necessary investment which will also be undertaken in that 5 year planning period (the AMP period).

At the time of undertaking the Milton Keynes WCS, Water Companies are preparing for Price Review 2009 (PR09), whereby they are currently drafting their Strategic Business Plans which seek funding for asset investment for the 5 year period covering 2010 – 2015 (known as AMP5).

It therefore follows that any new asset (or infrastructure) investment required to meet the requirements of the WCS, needs to feed into the drafting of the Strategic Business Plan for PR09. OFWAT will determine the final price limits from this process in November 2009. It can also be seen that, if significant WSI requirements are not included in this current price review (PR09), the funding cannot be sought for it until the next Price Review towards the end of AMP5 (PR14) which would result in funding not being available until AMP6 running from 2015 -2020.

The WCS is therefore essential for several reasons:

• It allows the discrepancies in the planning timeframes of AWS and MKC to be reconciled through strategic planning,

• It provides sufficient evidence base for MKCs statutory LDF process and robust evidence,

• It provides evidence for AWS Strategic Business Plans for investment required in AMP5 (2010- 2015) and beyond.

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Water Resource Planning

Water Companies are now required to produce Water Resource Management Plans (WRMP) on a statutory basis covering 25 year planning horizons. Previously, these plans have not been subject to public consultation.

WRMPs set out how a water company plans to provide and invest in existing and new water resource schemes (e.g. reservoirs, desalination) to meet increases in demand for potable supply, as a result of new development, population growth and climate change over the next 25 year period. When complete, the new statutory WRMPs will be updated in 5 yearly cycles to coincide with the Price Review and AMP process.

At the time of undertaking the Stage 1 Milton Keynes WCS, the WRMP09 is undergoing public consultation. Until such time as consultation is complete and the WRMP09 is approved and published in 2009, it is not possible to state with any certainty as to what options will be taken forward. However, data from the previous WRMP (04) has been made available and AWS has provided updates on the latest results from draft WRMP09.

It can therefore be seen that the WCS is crucial to bridging the gap between the LDF timeframe and the AWS planning timeframe in terms of strategic planning for new water resources to meet development.

2.2.4 Funding Mechanisms

Once the WCS has determined the requirement for new infrastructure it will be necessary for the following key stakeholders to agree to the WCS findings:

• MKC, MKP and EP - as the planning authority, delivery vehicle and landowners responsible for the growth in Milton Keynes,

• EA – planning, water resources, ecology and flood risk consultee as well as regulator for water quality,

• IDB – planning and flood risk consultee,

• AWS – as provider of wastewater and water supply infrastructure,

• NE – as statutory authority for protection of national and international sites of ecological interest and conservation.

Having due regard to the planning timeframes there will need to be stakeholder agreement on what infrastructure will be required (as recommended by the WCS) as well as when it will be required and how it will be funded and maintained.

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2.2.5 Water Framework Directive Planning

The WFD was passed into UK law in 2003. The overall requirement of the directive is that all river basins must achieve “good ecological status” (or good ecological potential in the case of artificial or heavily modified watercourses) by 2015 unless there are grounds for derogation. The WFD will, for the first time, combine water quantity and water quality issues together. An integrated approach to the management of all freshwater bodies, groundwaters, estuaries and coastal waters at the river basin level will be adopted. It will effectively supersede all water related legislation which drives the existing licensing and consenting framework in the UK.

UKTAG 3, the advisory body responsible for the implementation of the WFD in the UK, has proposed water quality, ecology, water abstraction and river flow standards to be adopted in order to ensure that waterbodies in the UK (including groundwater) meet the required status. These are currently in draft form and will not be formalised until the final River Basin Management Plans (RBMP) are finalised in December 2009 (prior to EU sign off). For this reason, it has not been possible to undertake a full assessment of the impact of trying to meet the new WFD standards, which in many cases, are likely to be stricter and more onerous to meet than those set by existing statutory targets and legislation. Despite this, the WCS is required to consider the longer term issues with respect to the water cycle and water environment and as such, an assessment of the impact of the interim WFD standards has been undertaken for this outline study.

3 The United Kingdom Technical Advisory Group (UKTAG) is a working group of experts drawn from environment and conservation agencies. It was formed to provide technical advice to the UK’s government administrations and its own member agencies. The UKTAG also includes representatives from the Republic of Ireland.

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3 Milton Keynes Growth Context

This Chapter describes the growth in Milton Keynes in more detail, specifically within the context of assessing or ‘testing’ the options for growth in terms of impacts on and the requirements of the water cycle.

As explained, draft RSS 9 has set out the growth development targets for Milton Keynes and surrounding areas to 2026. The SfG and Core Strategy production have included a broad scale assessment of the various options for potential development areas in Milton Keynes and have identified those development areas that have the potential to meet growth targets when considering all planning criteria.

It is important to note at this stage that the overall WCS is required to address, in detail, the additional growth targets up to 2026 as set out in the draft SE Plan, but to also consider the WSI and impacts on the water environment within the context of extrapolated growth up to 2031. This outline study has therefore considered the development areas and infrastructure required for both the short and longer term development aspirations for Milton Keynes.

3.1 New Housing Areas

The SfG (to 2026) for Milton Keynes pulls together information from previous studies and planning documents including the Milton Keynes Local Plan.

However, for the purpose of this outline WCS and to better represent the proposed development (and information obtained as part of this study), the following ‘broad’ study areas have been determined in conjunction with MKC and MKP (Figure 3-1):

• Central Area,

• Eastern Area,

• Western Area,

• Northern Area,

• South Western Area,

• Land East of M1,

• Rural Areas (including Hanslope, Olney, Newport Pagnell and Castlethorpe).

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These areas facilitate the incorporation of expansion areas, strategic reserve sites and rural housing sites identified in the Local Plan; the longer term ‘Strategic Development Areas’ south east and south west, urban intensification; and they allow for the consideration of phasing of development on an incremental basis.

Central Area

This study area covers approximately 2,640 hectares and has outline planning permissions for approximately 6,500 homes. Development proposals show major growth in the Central Area including infill development and in total it is proposed that there will be maximum of approximately 14,350 new homes in the Central Area up to 2026, plus a provision for 86 hectares of commercial land.

Eastern Area

This study area covers approximately 1,900 hectares including the Local Plan Eastern Expansion Area (land between Broughton/Atterbury, the A421, the M1, and the Coachway at Junction 14 (M1)) and Strategic Reserve Sites at Glebe Farm, Eagle Farm North and South, and Church Farm. Glebe Farm and Eagle Farm South are south of the A421. Church Farm is south of Wavendon and east of the existing city boundary. A Development Framework for the land north of the A421 (i.e. the Local Plan Eastern Expansion Area) proposes approximately 4,000 homes, employment land, local centre, secondary school, two primary schools and leisure and recreation open space (plus Eagle Farm North as an area of Strategic Reserve). Following discussions and input from both MKC and MKP, it has been determined that there will be a maximum total of approximately 13,000 new homes in the whole Eastern Area up to 2026 (including 5,600 within the administrative area of Mid Bedfordshire District Council as advocated in the RSS), plus a provision for 53 hectares of commercial land.

Western Area

This study area covers approximately 1,800 hectares of land to the south of Stony Stratford, south west of Two Mile Ash and north-west of Crownhill and Grange Farm (i.e. the Local Plan Western Expansion Area), and includes part of the South West Expansion Area as identified in the SfG. The Development Framework for the Local Plan Western Expansion Area includes approximately 6,000 homes, along with a public transport route linking the area to the city centre, a local High Street, one secondary school, four primary schools, 17 hectares of new employment land, open space, playing fields, allotments, community and health facilities and a new burial ground and remembrance garden.

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The area known as Stantonbury Park lies north of Wolverton Road and Stantonbury. The site is allocated for about 500 homes and approximately 60 hectares of open space, which will contribute to a new country park. The whole site covers an area of approximately 71 hectares.

Following discussions and input from both MKC and MKP, it is proposed that there will be a maximum total of approximately 10,000 new homes in the Western Area up to 2026, plus a provision for 29 hectares of commercial land.

Northern Area

This includes the smallest of the Local Plan expansion areas – the Northern Expansion Area. The Northern Expansion Area lies immediately west of Newport Pagnell, between Wolverton Road, Little Linford Lane and Linford Lakes - it includes the old Rocla Pipes site. The Northern Expansion Area proposes 455 homes and also includes 3.4 hectares of employment land (next to the M1) and land where a mixture of different uses are proposed.

Following discussions and input from both MKC and MKP, it is proposed that there will be a maximum total of approximately 3,000 new homes in the whole of the Northern Area up to 2026, plus a provision for 3 hectares of commercial land.

Land East of M1

Discussions with MKC have revealed that following revisions of the South East Plan, an additional 5,600 dwellings are to be provided in the area to the east of the M1, including the existing settlements of Moulsoe and North Crawley.

South Western Area

This study area covers approximately 2,191 hectares including the areas of Bletchley, Newton Longville and also the South West Expansion Area as identified in the SfG, GVA Grimley Report and SFRA. Following discussions and input from both MKC and MKP, it is proposed that there will be a maximum total of approximately 9,000 new homes in the South Western Area up to 2026 (with 5,390 in Aylesbury Vale), plus a provision for 3 hectares of commercial land.

Rural Areas

There are a small number of developments proposed to the rural settlements within the boundary of MKC. Whilst only relatively minor development is proposed in the Local Plan and the Core Strategy Preferred Options in and around Olney, Hanslope and Castlethorpe, consideration should still be given to the

Final December 2008 15 Milton Keynes Council Water Cycle Study – Outline Strategy

potential cumulative effect upon the water cycle within Milton Keynes. Newport Pagnell is also considered by MKC as a rural settlement.

Following discussions and input from both MKC and MKP, in total it is proposed that there will be a maximum total of approximately 3,000 new homes in the Rural Areas up to 2026, plus a provision for 0.1 hectares of commercial land.

Summary

A summary of the proposed residential development numbers considered in this outline WCS are show in Table 3-1.

Table 3-1: Potential Residential Development Numbers Study Area Dwellings Population* Central 14,350 32,862 Eastern 13,000 (inc 5,600 in Mid Beds) 29,770 South Western 9,000 (inc 5,390 in Aylesbury Vale) 20,610 Western 10,000 22,900 Northern 3,000 6,870 Land East of M1 5,600 12,824 Rural Settlements** 3,000 6,870 * Based on an occupancy rate of 2.29 (as agreed with MKC and MKP) ** Including Olney, Hanslope and Newport Pagnell

3.1.1 Infill Development

It is envisaged that approximately 14,350 new dwellings will be provided in the existing urban area of Milton Keynes. It is proposed that the infill housing within the existing urban area will be supplied through a combination of brownfield redevelopment (20% target), previously undeveloped land and redevelopment of windfall sites.

By its nature infill development occurs on a partially ad hoc basis, as and when land becomes available, therefore no definitive locations or growth targets for infill can be confirmed at this stage.

3.1.2 Marston Vale Eco-Town

The proposed Marston Vale Eco-Town is located to the east of the Milton Keynes study area and could have a minor impact upon the water cycle regime of Milton Keynes, if it reaches the final shortlist. The Eco-Town will need a new wastewater network, water supply and also generate surface water run off.

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Existing masterplans for the Eco-Town suggest that due to the topography of the surrounding area, natural drainage paths will be towards Bedford rather than Milton Keynes. An estimated 10% of the west of the development may gravitate to Cotton Valley which would require infrastructure upgrades. Reference should be made to the Outline WCS for Bedford and Mid Beds being undertaken by Bedford Renaissance. The final decision on the future of the Eco-town is expected in early 2009.

Any new development on Greenfield sites increases surface water run-off. Although it is envisaged that by the nature of the Eco-Town development, water recycling and water re-use would be encouraged. Also the EA and IDB (in line with PPS25) would require that any additional surface water run off should be attenuated to Greenfield rates, therefore there should be no net increase in surface water run off post development (should the Eco-Town go ahead).

The CLG Eco-Town Prospectus states that Eco-Towns should be examples of best practice in the fields of water and wastewater management. They should be working towards water neutrality and will utilise water efficiency methods. This should therefore mean the Eco-Town places a minimal demand upon existing water resources. If the Eco-Town is approved, then it will require its own WCS.

3.1.3 Development Scenarios – Housing

In undertaking the Milton Keynes WCS, it would be possible to assess potential broad development areas individually; however, it is important to consider that there are numerous ways in which the development can be brought forward in each area both in terms of numbers of housing, but also phasing of housing development. This gives rise to potential development ‘scenarios’.

It is not possible to consider all the permutations for how housing could be brought forward in each of the development areas and test each development scenario for implications to the water cycle within the limitations of this study. In the main, this is due to time constraints, but also because not all of the theoretical permutations for development would be possible due to other planning or sustainability reasons.

The WCS has therefore considered broad development scenarios to determine options for the phasing of development. As such, the total growth for each development area has been split down into a number of incremental steps (Table 3-2). This has allowed determination of constraints to development, both as a baseline (existing) and then through a number of discrete growth steps.

For the purpose of the wastewater network analysis, the growth phases have been broken down further, dependant upon the number of catchments draining each area. This has further helped with the determination of the location of development within each area, thus highlighting where infrastructure upgrades would be required and also determining sites which may be brought forward sooner (pre infrastructure upgrades).

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Table 3-2 Milton Keynes Development Scenarios Growth Horizons* (Homes) Area 1 2 3 4 Central 0-3,600 3,600-7,200 7,200-10,800 10,800-14,400 Eastern 0-3,250 3,250-6,500 6,500-9,750 9,750-13,000 South Western 0-2,250 2,250-4,500 4,500-6,750 6,750-9,000 Western 0-2,500 2,500-5,000 5,000-7,500 7,500-10,000 Northern 0-750 750-1,500 1,500-2,250 2,250-3000 Land East of M1 0-1400 14,00-2,800 2,800-4200 4,200-5,600 Olney 0-375 375-750 750-1,125 1,125-1,500 Hanslope 0-375 375-750 750-1,125 1,125-1,500 * Arbitrary growth horizons have been determined based on a quarter split of total development

3.2 New Employment Areas

In addition to the proposed residential growth, there is a substantial amount of non-residential growth proposed for Milton Keynes. In order to facilitate comparison with AWS data, non-residential development in this report includes designated employment areas, commercial and community facilities.

The largest proposed employment area by far is in the Local Plan’s Eastern Expansion Area. There are also other significant areas in the Local Plan’s Western Expansion Area, Shenley Wood and Tattenhoe Park and the city centre.

Table 3-3 shows the amount of floorspace proposed in each of the development areas based upon the employment land delivery programme supplied by EP.

Table 3-3: Non-residential Development by Area Area Non-residential area (ha) Central 86 Eastern 53 South Western 3 Western 29 Northern 3 Land East of M1 N/A Rural Settlements 0.1

Until further breakdown (and details) can be determined for the proposed non-residential development, broad assumptions have been required to determine the wider impacts on the water cycle.

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4 WCS Methodology

Broadly, this outline WCS has been undertaken in three steps (1a, 1b and 2):

4.1 Step 1a / Step 1b: Baseline Conditions and Capacity

Before consideration is given to any new infrastructure required to service new development for each of the development scenarios, it is important to consider the existing baseline with respect to the water cycle environment and infrastructure. There are two key reasons for this:

• To allow identification of any potential flood risk constraints and water environment constraints which would immediately restrict development of an area,

• To allow the identification of any spare capacity in the existing WSI; this would minimise the requirement for new infrastructure.

The baseline and constraints assessment has been undertaken in two distinct stages:

• Step 1a: flood risk constraints are assessed for each development area in isolation,

• Step 1b: water cycle baseline (and constraints) are identified for each of the water cycle disciplines (i.e. water resources, wastewater, etc.), with an assessment of the water environment baseline.

4.1.1 Constraints Matrix – Traffic Light Coding

Within each constraint category, a series of questions were formulated to identify for each of the study areas, the relevant important constraints associated, given the present situation and infrastructure provision. For the purpose of the constraints matrices these were amalgamated and put into generic categories outlined in Table 4-1. Stage 2 of the WCS will further identify how and whether these constraints can be overcome.

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Table 4-1 Generalised Constraints Traffic Light Matrix

Flood Risk Water Resources Wastewater Environment

There is existing raw water source nearby with spare license capacity. There is No environmental water available based on constraints were identified CAMS Methodology Where housing option can or when housing levels There is little or no Classification. The be accommodated within were considered perceived risk of flooding to Groundwater Vulnerability existing available sufficiently small that they the area. Classification - Low LP. headroom at WwTW and in were unlikely to materially The site is in Zone 3 sewers. increase impacts on groundwater source European sites. protection zone. The river quality classification is Good - A/B/C. There is an existing raw Medium risk of significant water source nearby but adverse effects as housing with no spare capacity. levels increase. Coding There is no water available Where WwTW has determined by lower level There is a perceived based on CAMS capacity to accommodate as a result of greater medium risk of flooding to Methodology Classification. the proposed growth, but proximity to sensitive the policy area. Floodplain The Groundwater the sewers are unlikely to features or a greater is likely to intersect Vulnerability Classification - have capacity and degree of dependence development areas. Intermediate LP. The river therefore may need upon WwTWs that are quality classification is The upgrading. currently contributing to site is in Zone 2 excessive phosphate groundwater source loading*. protection zone. High risk of significant There is no existing raw adverse effects as housing water source nearby. levels increase. Coding There is an over determined by higher level abstracted/over License Where major/significant as a result of greater There is a perceived high based on CAMS upgrade of WwTW and/or proximity to sensitive risk of flooding to the policy Methodology Classification. sewers are required to features or a greater area. The Groundwater accommodate the degree of dependence Vulnerability Classification - proposed growth. upon WwTWs that are High LP. The site is in currently contributing to Zone 1 groundwater source excessive phosphate protection zone. loading. * It is not possible at this stage to accurately determine the level of housing that would lead to significant adverse effects on European sites. This would require further investigation at Stage 2 into (for example) likely degrees of increase in phosphate loading associated with levels of additional housing. 4.1.2 Constraints Matrix

The resultant outcome was the formulation of a constraints matrix for each of the study areas. This has been completed for each of the housing options within each of the areas, and forms the background behind the identification of preferred growth / phasing.

The matrix has been designed so that the amount of subjective interpretation of the questions is minimised, and hence the traffic lights allocated are based on factual and quantitative data.

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The number of dwellings which have been identified in the matrices have been based on an interpretation of the data provided by MKC and MKP.

4.1.3 Use of the Matrix

The matrix is intended to provide a visual comparison of the appropriateness of development within each of the study areas, with respect to the housing scenarios. For each of the scenarios, a traffic light is applied, and the total number of “green” traffic lights can be directly compared to the total number of “red” traffic lights. Areas with a majority of “green” boxes would be preferred, or could be taken forward with minimal infrastructure work. Conversely areas with a majority of “red” boxes would require significant upgrades in order to facilitate development. It is however important to note that the matrix is a ‘broad brush’ summary, and that a detailed assessment should be undertaken as part of the detailed (stage 2) study.

4.1.4 Summary Matrix

A summary matrix has been provided for each of the study areas (Section 12). These show the limiting number of dwellings for each of the disciplines within each of the areas. The final limiting number will be the lowest value of these and represents the development figure for each of these areas without significant implications.

4.1.5 Constraints of the Matrix

Although the identification of the study areas can be undertaken through a visual comparison of the traffic light systems, it should be recognised that a “red” light in one of the constraints may in effect over-ride all other traffic lights (i.e. major ecological constraints may preclude/limit planned development, regardless of prevailing factors).

4.2 Step 2: Water Services Infrastructure Development Options

This step considers the WSI options which could be taken forward in order to facilitate the growth as set out in the development scenarios. Where Step 1 has identified a need for further infrastructure development, strategic scale options are considered which could fill the gap to meet the development targets and set out how these impact on each development scenario option to allow a comparative assessment of the options for taking development forward with respect to the water cycle.

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4.3 Data Limitations

Undertaking of the outline WCS has required a large amount of data collection and analysis, much of which has been reliant on the willingness of third parties to supply in order to allow the study to be progressed. In some cases, the availability of data with respect to WSI and future planning has not been available within the time required to undertake the assessment. In such cases, various assumptions have been used to enable the study to continue. Under each relevant topic, this report identifies what data has been used in each assessment and identifies where assumptions have been adopted and the reasoning behind these assumptions. Recommendations are also made for further, more detailed investigation in the detailed study.

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5 Flood Risk Baseline

A review of flood risk in the WCS is essential to ensure that:

• The risk of flooding to the broad growth areas is quantified and the development is steered away from high risk areas (Flood Zone 2 and Flood Zone 3),

• Any flood mitigation measures are planned in a strategic manner,

• There is no deterioration to existing communities’ standard of protection.

5.1 Flood Risk Identification Methodology

The aim of identifying the potential sources of flood risk to the study areas is to assess the risks of all forms of flooding to and from development, in order to identify any potential development constraints with respect to flood risk. PPS25 emphasises the need for a risk-based approach to be adopted by LPAs through the application of the Source-Pathway-Receptor model.

The Source-Pathway-Receptor model firstly identifies the causes or ‘sources’ of flooding to and from a development. The identification is based on a review of local conditions and consideration of the effects of climate change. The nature and likely extent of flooding arising from any one source is considered, e.g. whether such flooding is likely to be localised or widespread. The presence of a flood source does not always infer a risk. The exposure pathway or ‘flooding mechanism’ determines the risk to the receptor and the effective consequence of exposure. For example, sewer flooding does not necessarily increase the risk of flooding unless the sewer is local to the site and ground levels encourage surcharged water to accumulate. The varying effect of flooding on the ‘receptors’ depends largely on the sensitivity of the target. Receptors include any people or buildings within the range of the flood source, which are connected to the source by a pathway.

In order for there to be a flood risk, all the elements of the model must be present. Furthermore effective mitigation can be provided by removing one element of the model, for example by removing the pathway or receptor. In the case of Milton Keynes, the general consensus is the receptor (i.e. new development) be removed from the exposure pathway to a flood source

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5.2 Available data and Assumptions

The assessment of flood risk constraints was made using of the draft Level 1 SFRA produced for MKC. The draft Level 1 SFRA was drafted in March 2008 and covers an assessment of strategic flood risk in the administrative area of Milton Keynes from all potential sources of flooding, including fluvial, groundwater and overland flow. The draft Level 1 SFRA has been produced to allow MKC to undertake the PPS25 Sequential Test of potential development sites identified within their emerging LDF.

Information on potential SUDS utilisation has made use of Source Protection Zone (SPZ) information produced and published by the EA and Groundwater Vulnerability Maps produced by the National Rivers Authority (NRA).

Other Information Sources used include:

• Records of sewer flooding incidents (DG5) as reported to OFWAT and provided by AWS,

• Groundwater Vulnerability data from the EA.

5.3 Baseline Description

This assessment covers the risk of flooding and hence flood risk constraints posed to the potential development sites. Flood risk generated as a result of the development (from surface water flooding) is considered in Section 9 as this is considered on a development scenario basis and not as an absolute constraint.

5.3.1 Fluvial Systems

The Milton Keynes WCS area covers the catchments of the River Great Ouse and River Ouzel. Tributaries of these rivers include the River Tove, The Twins, Clipstone Brook, Loughton Brook, Tongwell Brook, Water Eaton Brook and Broughton Brook. Rivers, floodplain and flood defences are mainly heavily modified due to historic development, industry and agriculture. Table 5-1 provides an overview of the major catchment characteristics.

The Milton Keynes SFRA 4 and River Great Ouse CFMP 5 provide a more comprehensive assessment of river catchment characteristics.

4 Milton Keynes Level 1 Strategic Flood Risk Assessment - Draft, Halcrow (March 2008) 5 River Great Ouse Catchment Flood Management Plan – Consultation Draft Plan, Environment Agency (January 2007)

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Table 5-1 Major Catchment Characteristics Watercourse Major Tributaries Catchment Characteristics Largely agricultural, main urban areas River Tove, The Twins, River Great Ouse are Milton Keynes and Newport Loughton Brook Pagnell Clipstone Brook, Broughton Largely rural catchment, main urban River Ouzel Brook area is Milton Keynes

5.3.2 Catchment Geology

Geology maps for the area show that the north of Milton Keynes District is underlain by a major aquifer (predominantly limestone) of varying vulnerability. The bulk of the city limits is underlain by impermeable Oxford bed clays with pockets of minor aquifer and river terrace deposits along the watercourse fringes. The extreme south east corner of the district in the Woburn Sands area is underlain by a major aquifer (Lower Greensand) of high vulnerability.

5.3.3 Flood Defences

There are some significant raised flood defences in Newport Pagnell, Middleton and Fenny Stratford. The raised embankment at Kickles Bank has a design standard of 1 in 50 years, as have the raised embankments Tongwell Brook along Willen Road, and on the Ouzel along Willen Road, Caldecotte Street and Priory Street. As stated in the SFRA, the defences at Kickles bank are nominally 1 in 100 years as the water levels of a 1 in 100 year event are approximately 60cm lower than the crest of the embankment. The raised embankment at the EP site at Middleton has a SoP of 1 in 200 years.

Rivers, floodplain and flood defences are mainly heavily modified due to historic development, industry and agriculture.

There is also a network of balancing lakes throughout the study area which through their attenuation, ability to regulate flow and storage capacity provide an effective flood defence. The main lakes are Caldecotte and Willen which regulate flow into the Ouzel. There are also significant balancing lakes on Loughton and Tongwell Brook. Broughton Brook and Loughton Brook have both been reengineered to for development to include lakes, two stage channels and contained floodplains.

5.3.4 Overland Flow

Overland flow is water that fails to infiltrate the surface and travels over the ground surface. Overland flow can occur from significantly large areas of hardstanding, or from large areas of impermeable soil and or geology which quickly become saturated during rainfall events. In general, these conditions need to be

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combined with steep topography which can lead to rapid runoff from saturated (or impermeable) areas and channel high flowing water to developed areas.

Stoke Goldington has a history of flooding by overland flow. Discussions with the IDB have also revealed that the Caldecotte-Walnut Tree area suffers flooding.

5.4 Fluvial

Fluvial flood sources include sections of rivers not affected by the sea. The River Great Ouse flows to the north and west of the study area, the River Ouzel flows to the south and east of the study area, Broughton Brook flows to the east of the study area, Water Eaton Brook to the south of Milton Keynes, Tongwell Brook to the north east of Milton Keynes, Chinchley Brook to the north east of the study area and Loughton Brook to the west of the study area. The Flood Zones may be seen in the recently completed SFRA.

PPS25 defines three ‘flood risk zones’ with respect to fluvial flooding. The flood zones are classified in terms of flood risk from rivers based on probability of a flood event occurring. The fluvial flood zones are defined as:

• Zone 1 – Low Probability: land assessed as having a less than 1 in 1000 chance of river flooding occurring in any given year (or a less than 0.1% annual probability),

• Zone 2 – Medium Probability: land assessed as having between 1 in 1000 and 1 in 100 chance of river flooding occurring in any given year (or between 0.1% and 1% annual probability),

• Zone 3a – High Probability: land assessed as having a 1 in 100 or greater chance of river flooding occurring in any given year (or greater than 1% annual probability),

• Zone 3b – Functional Floodplain: land where water has to flow or be stored in times of flood. Generally, this is defined as land having a 1 in 20 or greater chance of flooding occurring in any given year (or greater than 5% annual probability),

Figure 5-1 outlines the extent of the flood zones (from the draft Level 1 SFRA) in relation to the broad growth areas for Milton Keynes.

For the purposes of the Level 1 SFRA, an agreement was reached with the EA over the use of proxy data. The proxy’s considered were:

• Functional Floodplain (Flood Zone 3b) for Water Eaton Brook Flood Zone 3b was determined using the 1 in 25 year modelled outline,

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• Functional Floodplain (Flood Zone 3b) for the River Ouzel between Water Eaton and Caldecotte was determined using the 1 in 50 year modelled outline,

• Functional Floodplain (Flood Zone 3b) for the remaining areas was determined using Flood Zone 3a as a surrogate.

This may be amended in the Level 2 SFRA if necessary.

5.4.1 Climate Change

PPS25 requires developments in floodplains to consider the potential impacts of climate change on flood risk for the lifetime of the proposed development.

EA guidance generally suggests that commercial developments should be considered to have a 60 year design life, and residential developments should be considered to have a design life of 100 years. In accordance with Annex B of PPS25, allowances for climate change should be made on fluvial flood sources for a 60 year and 100 year design horizon. This requires an assessment of the impact of an increase of 20% on peak river flows (or a 30% increase in rainfall intensity) for the design event being considered. In this case, the peak river flows predicted during flood event with a return period (or frequency) of 1 in 100 years needs to be increased by 20% (or rainfall intensity increased by 30%).

Where a modelled 1 in 1000 year outline exists (e.g. Water Eaton Brook), this has been used as a proxy outline for Flood Zone 3a plus climate change. Elsewhere, the existing Flood Zone 2 has been used as a proxy for Flood Zone 3a plus climate change.

Flood Zone 3a has been used as a proxy for Flood Zone 3b plus climate change.

5.4.2 Historical Flooding and Historical Flood Events

The draft Level 1 Milton Keynes SFRA has identified a number of historical events within the study area. The following locations have been highlighted within the SFRA, through consultation with stakeholders, through AWS data and the Stoke Goldington Flooding Investigation Report 6 as having particular flooding issues:

• Newport Pagnell,

• Stoke Goldington,

• Stony Stratford,

• Bletchley,

6 Stoke Goldington Flooding Investigation, WSP (October 2007)

Final December 2008 27 Milton Keynes Council Water Cycle Study – Outline Strategy

• Woburn Sands,

• Bow Brickhill,

• Central Milton Keynes,

• Walnut Tree,

• Lower Weald

• Great Linford.

The following incidents have been recorded; however no severity rating, return period for the flood event or details of antecedent conditions are available for these flood events:

• Newport Pagnell - 1947, 1992 and 1998,

• Stony Stratford - 1947,1998, 2003 and 2007,

• Bletchley - 1968, 1998 and 2006,

• Olney - 1947 and 1998,

• Fenny Stratford - 1947,

• New Bradwell - 1948, 1968 and 1998,

• Shenley Brook End - 1980,

• Walton Park - 2004 and 2007,

• Cosgrove - 1998,

• Ravenstone - 1980,

• Stoke Goldington - 1880, 1968, 1973, 1980, 1984, 2002 and 2007,

• Tathall End - 1973 and 2007,

• Woburn Sands - 2004.

5.4.3 Fluvial Flooding – Strategic Development Area Analysis

Central Area

The flood mapping from the draft Level 1 SFRA indicates that there are areas of flood risk (Flood Zones 3a, 3b and 2) along the eastern side of the town associated with the River Ouzel around Oakgrove, Walton and Monkston Park. There is also an area of flood risk to the north west of the town near Bradwell. The

Final December 2008 28 Milton Keynes Council Water Cycle Study – Outline Strategy

linear parks running alongside the River Ouzel should be retained and enhanced where possible. These linear parks can act as a form of flood risk mitigation measure. Flood risk should not be a major constraint to the proposed development within the Central Area as new development is unlikely to be permitted within areas of Flood Zones as the river corridors are maintained as green infrastructure and due to surface water attenuation prior to discharge.

Eastern Area

The flood mapping from the draft Level 1 SFRA indicates that there are areas of Flood Zone 2 and 3 in the eastern study area. There are also two areas of Flood Zone 2, 3a and 3b within the council’s core development area associated with Broughton Brook and the River Ouzel. Flood risk is not likely to be a major constraint to development within the Eastern Area as the bulk of development is to be located away from areas of Flood Zone 2, Flood Zone 3a and Flood Zone 3b. Also, the development framework for the Eastern Expansion Area states that the linear park alongside Broughton Brook will be protected, offering a form of flood risk management.

Western Area

There are areas of Flood Zone 2, 3a and 3b along the eastern edge around Shenley, Furzton and Loughton, and the North Western Area around Stony Stratford and Calverton. These flood zones are associated with Loughton Brook and the River Great Ouse. The core development area is however outside of Flood Zones 2, 3a and 3b. Flood risk is therefore not considered to be a major constraint to the proposed development within the Western Area due the very small area of the Expansion Area located within Flood Zone 2 or 3, which is located to the extreme south and west of the area.

Northern Area

The draft Level 1 SFRA Flood Zone maps show that there are large areas of Flood Zone 2, 3a and 3b within this study area. These Flood Zones are associated with the River Great Ouse and River Ouzel. The core development areas are however situated outside of the Flood Zones. Given this, flood risk should not be a major constraint to the proposed development within the Northern Area.

South-Western Area

The draft Level 1 SFRA flood mapping indicates that the southern half of the study area has areas of Flood Zone 2, 3a and 3b adjacent to Water Eaton Brook, particularly in Water Eaton. It is however a narrow Flood Zone immediately adjacent to the watercourse. Flood risk is not a major constraint to the proposed development within the South Western Area as new development is unlikely to be permitted within Flood Zones, any permitted development would need to incorporate flood resilience measures.

Final December 2008 29 Milton Keynes Council Water Cycle Study – Outline Strategy

Land East of M1

There are areas of Flood Zone 2, Flood Zone 3a and Flood Zone 3b associated with Chicheley Brook and the River Ouzel within the broad growth area. The main areas of fluvial flood risk are to the south of Chicheley, Brook End, Crawley Grange and Newport Stables . Flood risk should not be a major constraint to development within this expansion area as new development is unlikely to be permitted within flood risk areas and any development that is, would need to incorporate effective flood resilience measures..

Rural Areas

The draft Level 1 SFRA flood mapping indicates that Olney has large areas of Flood Zone 2, 3a and 3b associated with the River Great Ouse adjacent to the southern and eastern edges of the settlement. The draft Level 1 SFRA Flood Zone maps show that there are large areas of Flood Zone 2, 3a and 3b around Newport Pagnell. The settlement of Hanslope does not have any areas of Flood Zone 2 or 3 nearby and so flood risk is not a constraint to proposed development in the Rural Areas.

It is important to note that through careful mitigation measures such as the EA have confirming that they would not approve of development within the floodplain or as a justification to construct flood risk management infrastructure, fluvial flooding need not be a major constraint to development in any of the areas proposed for development in Milton Keynes. Maintenance and expansion or enhancement of the linear green corridors adjacent to the watercourses in Milton Keynes, maintenance of Greenfield runoff rates and application of other mitigation measures such as SUDS will also facilitate the removal of flood risk as a major constraint, provided that greenfield runoff rates are maintained. More detailed assessment of flood risk in each of the expansion areas can be found in Section 12.

5.5 Sewers

Normally, flooding from sewers occurs as a result of exceedance of the capacity of the sewer system from heavy rainfall or if the system becomes blocked and will continue to remain flooded until the water drains away. Modern sewer systems are typically designed to accommodate rainstorms with a 30 year return period, whilst older sewer systems were often constructed without consideration of a design standard and may in some areas (served by Victorian sewers) have an effective design standard of less than 30 years. However, as the majority of the sewer network serving Milton Keynes is a separated system, then sewer flooding issues can be split into two main groups:

• Foul sewer flooding – usually as a result of undersized pipes, blockages or constrictions. Where there is an existing issue with the capacity of the network, any new connections without upgrades will only make the situation worse.

Final December 2008 30 Milton Keynes Council Water Cycle Study – Outline Strategy

• Surface water sewer flooding – usually as a result of incapacity in the system during intense rainfall events which overwhelm the network (i.e. events with a return period greater than 1 in 30 years). The impacts of climate change are also leading to more surface water sewer flooding in the UK, with milder, wetter winters and increased rainfall intensity in summer months likely to become the norm.

In order to fulfil statutory commitments set by OFWAT, water companies must maintain verifiable records of sewer flooding. The register of sewer flooding where caused by hydraulic incapacity is referred to as the DG5 register.

DG5 register internal flooding is defined as flooding which enters a building or passes below a suspended floor; whilst external flooding is defined as flooding which is not classed as internal. Properties at risk are defined as properties that have suffered or are likely to suffer internal flooding from public foul, combined or surface water sewers due to overloading of the sewerage system more frequently than the relevant period. All flooding incidents should be registered by the water company irrespective of the severity of the storm. For reporting purposes, buildings are restricted to those normally occupied and used for residential, public, commercial, business or industrial purposes7.

The draft Level 1 SFRA for Milton Keynes noted that incidences of internal and external sewer flooding have occurred in:

• Wolverton (4 records in DG5 Register),

• Bletchley (5 records in DG5 Register).

5.5.1 Sewer Flooding – Strategic Study Areas Analysis

A description of sewer flooding instances within each strategic study area has been undertaken below. It is important to note that the data supplied was limited in detail and hence the exact nature and extent of all events is in many circumstances is unknown.

Central Area

AWS data has identified instances of flooding in Bradwell Common, Heelands, Eaglestone, Bean Hill and Springfield. The exact nature and extent of these events is not however known.

Eastern Area

AWS data has identified instances of flooding in Willen, Wavenden and Woburn Sands. The exact nature and extent of these events is not however known. AWS have also confirmed that there are known issues relating to the incapacity of the sewers in this area.

7 Environment Agency, Upper Mersey CFMP, May 2008

Final December 2008 31 Milton Keynes Council Water Cycle Study – Outline Strategy

Western Area

AWS data has identified instances of flooding in Stony Stratford, Loughton and Shenley. The exact nature and extent of these events is not however known.

Northern Area

The SFRA (through DG5 data) and additional AWS data has identified instances of sewer flooding in Wolverton and other instances of flooding in Stantonbury and Great Linford. The exact nature and extent of these events is not however known.

South Western Area

The SFRA (through DG5 data) and additional AWS data has identified instances of sewer flooding in Bletchley and other instances of flooding in Fenny Stratford, Water Eaton and Newton Longville. The exact nature and extent of these events is not however known.

Land East of M1

AWS data has identified instances of sewer flooding in Moulsoe. The exact nature and extent of these events is not however known.

Rural Areas

The SFRA (through DG5 data) and additional AWS data has identified instances of sewer flooding in Newport Pagnell. There is a risk of flooding from the lagoons at Newport Pagnell; however there are no known artificial sources of flooding in Olney and Hanslope. There are no further recorded instances of sewer flooding in the rural settlements of Olney or Hanslope.

Summary

Due to the nature of data supplied, it has not been possible to shown the instances of sewer flooding in great detail. The SFRA should be referred to for greater detail.

5.6 Surface Water

Surface water flooding, also known as pluvial or overland flooding can occur as a result of a number of factors. During periods of prolonged rainfall events and intense downpours, overland flow from adjacent higher ground may ‘pond’ in low-lying areas of land without draining into watercourses, surface water drainage systems or the ground. In general, surface water drainage systems are only required to be designed to contain a 1 in 30 year rainfall event (as a maximum), during higher intensity events, surface water drainage systems become overwhelmed often resulting in surface water flooding.

Final December 2008 32 Milton Keynes Council Water Cycle Study – Outline Strategy

One of the main issues with surface water flooding is that in areas with no history, relatively small changes to hard surfacing and surface gradients can cause flooding (garden loss and reuse of brownfield sites for example). As a result, continuing development could mean that pluvial and surface water flooding can become more frequent and although not on the same scale as fluvial flooding, it can still cause significant disruption.

Historically the surface water generated as a result of development within Milton Keynes has been attenuated via one of a number of attenuation lakes, prior to discharge into the watercourse network. The lakes were designed to:

“avoid increasing flood risk through development……….…..the lakes have, subject to certain conditions being met, a capacity sufficient for the long-term development of Milton Keynes within the drainage area. The design standard was the 1947 flood that was, and remains, the most severe on record” 8.

It should however be noted that whilst the surface water system for Milton Keynes was designed to the 1947 standard, this does not preclude the incorporation of new and specific surface water management into new developments as the impacts of climate change and increase in population densities are increasing the pressure upon surface water management within Milton Keynes. These measures are necessary in the expansion areas and for sites outside the Designated Area (DA). The exact return period of the 1947 event is also unknown and caution should be applied when considering this as a design standard.

5.6.1 Surface Water Flooding – Strategic Study Areas Analysis

Central Area

There are several recorded instances of surface water flooding within the Central Area. The SFRA has recorded instances in Conniburrow, Fishermead, Oldbrook, Beanhill and Netherfield.

Eastern Area

There are recorded instances of surface water flooding in Woburn Sands, Wavendon and Bow Brickhill. The proposed core development area within the Eastern Area will primarily be constructed on Greenfield land. Greenfield land is land that has never been built on or where the remains of any structure or activity have blended into the landscape over time. The amount of impermeable land is therefore likely to increase and it would be necessary to ensure SUDS techniques are employed and maintained to reduce runoff rate to that of greenfield rate in any development. Greenfield run-off rate is the surface water drainage regime from a site prior to development, or the existing conditions for brownfield redevelopment sites.

8 Drainage Strategy for Milton Keynes, Halcrow 2004

Final December 2008 33 Milton Keynes Council Water Cycle Study – Outline Strategy

Western Area

There is a recorded instance of surface water flooding in Stony Stratford. The proposed core development area within the Western Area will primarily be constructed on Greenfield land. The amount of impermeable land will therefore increase and it would be prudent to ensure SUDS techniques are employed and maintained to reduce runoff rate to that of greenfield rates to minimise any potential increase in surface water runoff.

Northern Area

There are several recorded instances of surface water flooding in New Bradwell, Greenleys, Bradville, Wolverton, and Great Linford. The proposed core development area within the Northern Area will primarily be constructed on Greenfield land. The amount of impermeable land is therefore likely to increase and it would be prudent to ensure SUDS techniques are employed and maintained to reduce runoff rates to that of greenfield rate any potential increase in surface water runoff.

South Western Area

There are several recorded instances of surface water flooding in Bletchley. Any development on Greenfield land will increase the amount of impermeable land and would therefore it would be important to ensure SUDS techniques are employed and maintained to reduce runoff rate to that of greenfield rates to minimise any potential increase in surface water runoff.

Land East of M1

According to the SFRA there are instances of surface water flooding in Moulsoe and North Crawley. Any development on greenfield land will increase the amount of impermeable land and would therefore it would be important to ensure SUDS techniques are employed and maintained to reduce runoff . These should be limited to greenfield rates to minimise any potential increase in surface water runoff.

Rural Areas

There are several recorded instances of surface water flooding within the rural settlements. The SFRA notes surface water flooding in Hanslope, Stoke Goldington, Castlethorpe, Newport Pagnell, Olney and Weston Underwood. Any development on greenfield land will increase the proportion of impermeable surfaces and it would therefore be important to ensure SUDS techniques are employed and maintained to reduce runoff rate to that of greenfield rates to minimise any potential increase in surface water runoff.

Final December 2008 34 Milton Keynes Council Water Cycle Study – Outline Strategy

5.7 Groundwater

Groundwater flooding occurs when groundwater levels rise above prevailing ground levels. The majority of Milton Keynes city is situated above impermeable boulder clays meaning that groundwater flooding is unlikely. The area to the north of Central Milton Keynes (around Hanslope and Olney), the area to the north of Wolverton and the area around Woburn Sands are underlain by permeable geology (limestone and Lower Greensand). The SFRA states that the IDB have expressed concerns that increased development and use of infiltration SUDS in the area could lead to localised groundwater flooding.

5.7.1 Groundwater Flooding – Strategic Study Areas Analysis

Central Area

It is considered that the risk of groundwater flooding in Central Area are low due to the nature of the underlying geology (relatively impermeable and clayey). There are narrow pockets of river terrace deposits immediately adjacent to the watercourses which have a higher permeability but overall the risk of groundwater flooding is considered to be low.

Eastern Area

The area around the settlement of Woburn Sands is underlain by permeable sands and gravels. There is therefore a potential risk of groundwater flooding in the area, although there are no recorded instances.

Western Area

It is considered that the risk of groundwater flooding in the Western Area are low due to the underlying geology being relatively impermeable (clayey). There are narrow pockets of river terrace deposits immediately adjacent to Loughton Brook which have a higher permeability, however the risk of groundwater flooding is considered to be low.

Northern Area

It is considered that groundwater flood risk in the development areas in the Northern Area are low due to the underlying geology being relatively impermeable (clayey). There are narrow pockets of river terrace deposits immediately adjacent to the River Great Ouse and River Ouzel which have a higher permeability. A small area of major aquifer also underlies the area to the north of Wolverton, however the risk of groundwater flooding is considered to be low.

South Western Area

It is considered that the risk of groundwater flooding in the South Western Area is low due to the underlying geology being relatively impermeable (clayey). Towards the far east of the area, sands and gravels

Final December 2008 35 Milton Keynes Council Water Cycle Study – Outline Strategy

become more prevalent and subsequently more permeable. Overall, groundwater flood risk is still considered to be low.

Land East of M1

It is considered that groundwater flood risk in this expansion area is low due to the underlying geology being relatively impermeable (Kellaway formation and Oxford Clay). The east of this area is overlain with drift deposits of a till-diamicton mix.

Rural Areas

Hanslope, Newport Pagnell and Olney are underlain by large areas major aquifer (Oolitic Limestone ) with a high vulnerability meaning that there is a potential risk of groundwater flooding. However, there are no recorded incidences of groundwater flooding.

5.8 Artificial Sources

Artificial flood sources include raised channels such as canals, or storage features such as ponds and reservoirs. The SFRA identified that there was a breach of the Grand Union Canal in the Woughton Park area of Milton Keynes in 1971 following third party work.

Breach or overtopping of reservoirs also poses a risk to development. There are thirteen reservoirs located within the study area, where these have a perceived risk; more detailed analysis should be undertaken as part of the Level 2 SFRA.

Central Area

The SFRA has identified that the Grand Union Canal runs through the Central Area and carries with it an associated flood risk. The SFRA also points out that there was a reported breach of the canal in the Woughton Park area following third party works.

There are also a number of reservoirs and ponds to the north east of the Central Area. Any major risk to development should be identified and addressed either as part of the Level 2 SFRA or as part of a site specific flood risk assessment (FRA).

Eastern Area

Willen Lake is situated in the north west of this area and carries a flood risk in the form of overtopping, or potentially breach. Any major risk to development should be identified and addressed either as part of the SFRA or as part of a site specific FRA.

Final December 2008 36 Milton Keynes Council Water Cycle Study – Outline Strategy

Western Area

There are several reservoirs, ponds and lakes in the east and south east of this area which carry an associated flood risk through overtopping, or potentially breach. Any major risk to development should be identified and addressed either as part of the SFRA or as part of a site specific FRA.

Northern Area

There are numerous lakes and reservoirs in the north and west of the area. These waterbodies carry with them an associated flood risk in the form of overtopping, or potentially breach. Any major risk to development should be identified and addressed either as part of the SFRA or as part of a site specific FRA.

South Western Area

There are several balancing ponds and lakes in the Bletchley and Newton Longville area which have an associated flood risk. Any major risk to development should be identified and addressed either as part of the SFRA or as part of a site specific FRA.

Land East of M1

There are no identified artificial sources of flooding within this expansion area.

Rural Areas

There is a risk of flooding from the lagoons at Newport Pagnell; however there are no known artificial sources of flooding in Olney and Hanslope.

5.9 Flood Risk Constraints Summary

The assessment of flood risk undertaken for each study area at the present time, as a summary of the constraint ranking is shown in Table 5-2, with a summary of the identified constraints shown in Table 5-3.

Table 5-2 D escription of Colouring Assigned to Flood Risk Constraint Table

No / negligible issue – small scale management and mitigation may be required

Significant constraint – Feasible, but significant management and mitigation required

Major constraint

Final December 2008 37 Milton Keynes Council Water Cycle Study – Outline Strategy

Table 5-3 F lood Risk Constraint Assessment

Drainage / Surface Area Fluvial Groundwater Artificial Flooding Water

Areas of Flood Zones 2 GUC runs along the and 3 in the west of the There are recorded eastern edge of Central Underlying geology is Central area associated with the instances of surface water Milton Keynes. There predominantly impermeable River Ouzel. Fluvial flooding are several lakes in the flooding has occurred* area** Areas of FZ 2 and 3 GUC runs along the There are recorded Risk of groundwater flooding affecting the northern part western edge of the instances of surface water around Woburn Sands site Eastern of this area associated eastern expansion area. flooding in the Woburn associated with sandy with River Ouzel and There are several lakes area permeable geology Broughton Brook* in the area**

Areas of FZ 2 and 3 in the There are recorded east of the area Underlying geology is There are several lakes Western instances of surface water associated with Loughton predominantly impermeable in the area flooding in Stony Stratford Brook*

Low risk of groundwater Areas of FZ 2 and 3 Instances of sewer flooding associated with an There are several lakes Northern associated with the River flooding recorded in DG 5 area of more permeable in the area Ouse* register in Wolverton, geology to the north of Wolverton

Areas of FZ 2 and 3 Instances of sewer South Underlying geology is There are several lakes affecting Water Eaton and flooding recorded in DG 5 Western predominantly impermeable in the area Caldecotte* register in Bletchley

Areas of Flood Zone 2 and Surface water flooding in Land East Underlying geology is No artificial sources 3 associated with Moulsoe and North of M1 predominantly impermeable nearby Chicheley Brook Crawley

Areas around Newport Areas of FZ 2 and 3 in Pagnell, Olney and Hanslope Rural Surface Water Flooding in No artificial sources Newport Pagnell, Olney are underlain by Oolitic areas Newport Pagnell nearby and Newton Blossomville* Limestone, which poses a groundwater flooding risk * Even though parts of the broad development areas may fall within Flood Zone 3, the EA have confirmed that they would not approve of development within the floodplain or as a justification to build defences. Therefore given this approach it is considered that fluvial flood risk should not be considered as a major constraint to development. ** Through assessing any risk of flooding from artificial sources as part of the SFRA or site specific FRAs, any risk of flooding could either be managed or mitigated.

Final December 2008 38 Milton Keynes Council Water Cycle Study – Outline Strategy

It can be summarised that there are no overriding flood risk constraints to any of the study areas that would require large-scale flood risk management or mitigation. There is little to differentiate between the areas, but the following points can be made:

• The Rural Areas have less potential issues than the other areas,

• Fluvial flooding is not considered to be a significant constraint to development within Milton Keynes. Even though parts of the study areas may fall within Flood Zone 3, the EA have confirmed that they would not accept development within the floodplain or permit the construction of new flood risk management infrastructure to facilitate development. The Green Infrastructure Study and the Development Frameworks both emphasise the importance of the green corridors and recommends that they should be maintained and enhanced,

• Surface water and drainage flooding has occurred on several occasions in the past throughout Milton Keynes. Taking into account increases in development, development densities and climate change predictions, it is likely that this type of flooding will increase in the future. Similarly older surface water sewers (or combined networks) may be overwhelmed with the increased volume of rainfall and sewer flooding may be experienced more frequently without network upgrades,

• Consideration should be given to the development of a surface water model for Milton Keynes as part of the detailed (stage 2) WCS. It may also be prudent to undertake a Surface Water Management Plan (SWMP) and network analysis, either as part of the detailed (stage 2) WCS, or in parallel.

• Milton Keynes is based on strategic and integrated surface water and flood risk management systems and SUDS

• It is also important that the MK WCS should link in to adjoining WCS’s to ensure a more regional assessment of the water cycle is considered.

5.10 Data Limitations

In addition to any data limitations reported upon in the draft Level 1 SFRA, the only limitations determined as part of the outline WCS are documented below:

• Functional Floodplain has mostly been mapped using proxies, with Flood Zone 3a typically being used as a proxy for Flood Zone 3b. In the case of Milton Keynes, this has not been considered to be too inhibitive as the EA are unlikely to support any proposed development in Flood Zone 3a,

Final December 2008 39 Milton Keynes Council Water Cycle Study – Outline Strategy

• There are some areas which will require further modelling for impacts of climate change, although where there is any major impact upon development sites it is likely that modelling would be undertaken as part of the Level 2 SFRA,

• It has been considered that although the Level 1 SFRA is only at draft stage, given the initial comments from the stakeholders, it is unlikely that there will be any significant changes. Any significant changes to the Level 1 SFRA, will be considered and documented in the Final Outline WCS (where appropriate).

Final December 2008 40 Milton Keynes Council Water Cycle Study – Outline Strategy

6 Wastewater Baseline and Capacity

The wastewater baseline and capacity assessment addresses two key areas for wastewater. Firstly, the baseline with respect to treatment of wastewater and how much ‘spare’ capacity is available in existing wastewater treatment facilities; and secondly, the baseline with respect to sewer network and whether there is scope to use the existing network system before upgrades are required. By the network system, this assessment refers to the network of gravity sewers, pumping stations and associated rising mains which are used to transmit wastewater from domestic and non-domestic developments to treatment facilities.

It is important to establish an indication of flow consent capacity of wastewater treatment facilities to enable any issues relating to flood risk and Water Framework Directive associated with an increase in the consent to be assessed. Capital investment costs also need to be assessed as part of the evidence base for the LDF process.

In order to give an indication of the relative sewerage infrastructure costs (which would be developer funded through requisition) it is important to consider, where possible, the level of off-site upgrades required.

A key priority of the WCS approach is the use of existing facilities, and where required, development of strategic upgrades solutions. This is to reduce cost, reduce impact to existing communities and to allow early phasing of some new development which will not have to rely on longer lead in times associated with securing funding for new infrastructure through the statutory water company planning process. It is important to note that there may be some WwTWs where there are major constraints to extension of the works which may be associated with planning (e.g. odour impact), flood risk, land availability.

A critical aspect in assessing the spare capacity of the wastewater treatment facilities is the assessment of the environmental capacity of the receiving watercourses. Discharge of additional treated wastewater from new development could have a detrimental impact on:

• Water quality of receiving waters,

• Hydrological/hydraulic regime of receiving water’s and associated habitats,

• Flood risk downstream of the discharge associated with extending the WwTW,

• Flood risk associated with extending WwTW.

This assessment of environmental capacity with respect to wastewater discharge is included in this section.

Final December 2008 41 Milton Keynes Council Water Cycle Study – Outline Strategy

6.1 Available Data and Assumptions

6.1.1 Data

Various types of information have been supplied by AWS for the wastewater baseline assessment:

• WwTW population equivalent (PE), location and discharge consent details,

• Location of sewer flooding incidents (for cause see SFRA),

• Coverage of sewer network models,

• Sewer network records in GIS format. These show the layout of the sewer network and include information such as sewer pipe sizes, sewer type, gradient etc,

• Information on existing capacity relating to all WwTWs.

6.1.2 Assumptions

The following assumptions have been considered whilst assessing the wastewater baseline and capacity:

• The per capita consumption (G - water used per head per day) is taken as 0.137 m 3h-1.d. This figure is based on the year 2006-2007 AWS regional average for metered houses (assume all new dwellings will be metered),

• The domestic populations (P) served by relevant WwTWs within Milton Keynes are those as provided by AWS,

• Total population equivalent (PE) served includes trade effluent, holiday population and tanker wastes and are those as provided by AWS,

• The average occupancy rate is 2.29 people per household (figure used by MKC),

• The infiltration (I) rate (defined as the amount of water that enters the drainage system from other sources such as saturated ground, illegal connections and unaccounted drains) has been assumed to be 25% (it has since been noted that AWS work on a figure of 45 l/c.d) of the Milton Keynes’ population multiplied by the per capita consumption9 (PG) for current and that for future calculation of I, the additional Infiltration is calculated as 25% of future PG,

• From data provided by AWS, it would appear that the sewer network is predominantly a separated system in Milton Keynes, i.e. foul water network is separate from surface water drainage network. There is a predominantly combined system at Bletchley and Wolverton and therefore the risk of

9 Based on Office of Water Services (OFWAT) standards

Final December 2008 42 Milton Keynes Council Water Cycle Study – Outline Strategy

surcharge from combined sewer overflows (CSO). AWS have indicated that the outlying towns and villages have combined systems.

• No change in holiday or trade PE,

• It cannot be stated with any certainty as to how the increase employment (approximately 174 ha) is to be defined and hence what affect it will have on increased trade flow. It has been assumed that the mainly office type work and light industry and warehousing focus will result in a conservative increase in trade flow of 30% above the current trade effluent total,

• In keeping with the requirements of PPS25 and EA policy, new development on existing Greenfield sites will be required to provide sustainable drainage measures whereby runoff rates do not exceed the Greenfield runoff rates. As such only increases in wastewater need to be considered in terms of the impact on hydraulic capacity of the receiving water.

6.2 Wastewater Treatment Baseline and Capacity

6.2.1 Existing Waste Water Treatment Works

There are three main WwTW (Cotton Valley, Olney and Hanslope) that are most likely to be affected by the proposed future development of Milton Keynes (due to the nature of the existing wastewater system), these are summarised along with other WwTWs within the study area in Table 6-1. The locations of the WwTWs are shown in Figure 6-1.

The largest, and most significant WwTW in terms of potential to accept additional influent, is Cotton Valley WwTW. This currently serves 261,244 population equivalent (PE), and has a dwelling capacity estimated from headroom on the consented flow of 55,560. This figure relates to the estimated flow headroom available before a revised consent is required. It should be noted that AWS have worked on an occupancy of 2.1 people per dwelling, compared to the figure of 2.29 used by MKC.

Final December 2008 43 Milton Keynes Council Water Cycle Study – Outline Strategy

Table 6-1 : Waste Water Treatment Works within Milton Keynes

Total PE Estimated Approx Domestic Consented WwTW (includes actual DWF Dwelling OS NGR PE DWF (m 3 d-1) trade PE) (m 3d-1) Capacity Cotton Valley 218,961 261,244 78,000 53498 55,560 SP88474055 Olney 6,650 6,663 1,250 1728 0 SP88805280 Hanslope 2,155 2,216 840 507 755 SP79404740 Lavendon 1,223 1,223 295 223 163 SP91205250 Castlethorpe 998 1,031 151 138 29 SP79564375 Sherington 954 954 206 232 0 SP88094625 Ravenstone – Stoke 728 745 160 150 23 SP84764880 Goldington North Crawley 689 689 123 104 44 SP91444496 Newton 324 324 75 70 11 SP93125119 Blossomville Weston 162 162 - - - SP86745034 Underwood Filgrave 118 118 - - - SP86894832 Astwood 96 96 50 45 11 SP94864740 Wavendon – 61 61 - - - SP92853773 Lower End Hardmead 42 42 - - - SP93824742 (New) Great Linford 35 35 - - - SP85394282 Gayhurst 20 20 - - - SP85004670 Newport Pagnell 29 29 - - - SP88714296 – London Road Whaddon 718 735 162 151 25 SP81223430 Drayton Parslow 555 555 106 98 18 SP84802870 Ducksworth 7 7 - - - SP96514784

NB WwTW with PE < 250 do not required a consented flow

6.2.2 Wastewater Treatment Capacity Assessment

Planned capital investment by AWS during AMP4 (2005 to 2010) is expected to ensure compliance with effluent consent at Cotton Valley until at least 2021. The scope of works is to increase the hydraulic capacity of the inlet works and re-commission secondary treatment activated sludge streams. The

Final December 2008 44 Milton Keynes Council Water Cycle Study – Outline Strategy

anticipated overall effect of these works is to increase the overall design process capacity to approximately 340,000 PE (an increase of roughly 79,000 PE).

The phasing of growth (residential and commercial) is important. Broadly speaking, the AMP4 investment at Cotton Valley is anticipated to satisfy about two thirds of the planned growth of Milton Keynes, which should accommodate development to at least 2021.

The forgoing analysis does not include capacity and potential expansion of the smaller WwTWs in and around Milton Keynes. These currently range from 7 PE to 6,000 PE and have a combined consented flow capacity of 1,080 houses (approximately 2,200 PE). A sewage network analysis would be required to investigate the feasibility for these respective works to accept additional influent.

It should also be noted that Olney and Hanslope WwTWs all have land available within their current boundary for expansion.

Whilst these assumptions are acceptable for the Stage 1 WCS to determine the outline feasibility of using the volumetric headroom at the WwTWs, any Stage 2 WCS will need to consider the ‘process’ capacity at the WwTW as this could limit the extent to which the volumetric capacity can be utilised in the time before funding is required to upgrade the WwTW. Any new upgrades or infrastructure requires funding to be sought by AWS and as such, there is an associated lead in time for the upgrade works which would limit the amount of development that could take place before the upgrades are in place.

Assumption sensitivity

The conclusions for the housing that can be accommodated by the existing capacity of the WwTW are sensitive to assumptions applied to the calculations, and in particular to the assumption applied to the per capita consumption. With the publication of the Code for Sustainable homes there is a considerable drive to move towards more water efficient developments where water consumption is reduced by a number of measures. A reduction in water usage would significantly reduce the wastewater generated from new properties which could result in more properties being able to be connected prior to existing flow headroom capacity being reached.

6.3 Wastewater Network Baseline and Capacity

6.3.1 Wastewater Network Baseline

AWS is responsible for the operation and maintenance of the existing foul drainage network and sewage treatment facilities, within the Milton Keynes study area. The Milton Keynes study area is predominantly served by a separate sewerage system which largely drains to Cotton Valley WwTW located to east of

Final December 2008 45 Milton Keynes Council Water Cycle Study – Outline Strategy

Milton Keynes. It should be noted that, whilst Milton Keynes itself is nominally separate, the older outlying towns and villages have combined (foul and surface water) systems. Figure 6-2 outlines the current layout of pipe drainage within the Milton Keynes.

The initial starting point for the outline WCS was to determine the existing levels of wastewater conveyed through the system in order to determine where there may be capacity issues both now and also in respect to the proposed development within Milton Keynes.

The initial capacity assessments may help with guiding development proposals away from areas where there are capacity issues, which would mean major capital investment and/or disruption for upgrades necessary to serve new sites. Given that the majority of the sewer network serving Milton Keynes is a separated system, the effects of increased flows due to climate change have not been considered to be a major issue.

Drainage paths and catchments were determined for all of the development areas, in some cases the development areas were further sub-divided based on their catchment characteristics.

High level preliminary assessments of the capacities of these drainage paths were then undertaken (Appendix B). This was undertaken to provide an indication of whether it is feasible to drain any of the proposed growth locations via the existing network.

With regards to addressing constraints within the wastewater network, the following has been considered:

• Minor Constraint – Less than 10% of network showing capacity issues,

• Significant Constraint – Between 10% and 30% of network showing capacity issues,

• Major Constraint – Greater than 30% of network showing capacity issues.

An assessment of each area is shown below. Further details are included in Section 12.

Central Area – Western

The initial assessment has shown that, in general the network draining the west of the Central Area, has capacity to service the proposed growth up to the upper growth targets, per area, as tested in Section 12). The assessments have highlighted that 18% of the network currently has capacity issues; however the majority of the system would likely be able to accommodate in excess of 4,500 homes.

Central Area – North East

That initial assessment has shown that there are major capacity issues in the network draining the north eastern part of Milton Keynes. The initial assessments show that 56% of the network is currently suffering from capacity issues. Without improvements works, further development in this area would only

Final December 2008 46 Milton Keynes Council Water Cycle Study – Outline Strategy

exacerbate the problem. The remainder of the network appears to have sufficient capacity to accommodate in excess of 4,500 homes within the north eastern part of the Central Area.

Central Area – South East

The initial assessment has shown that the network draining the south eastern part of the Central Area generally has capacity to service the proposed growth up to the maximum growth targets. The assessments have highlighted that 23% of the network currently has capacity issues; however the majority of the system (circa 76%) would likely be able to accommodate in excess of 4,500 homes.

Eastern Area – South

The initial assessment has shown that approximately 39% of the network draining the southern part of the Eastern Area suffers from capacity issues. Works will be required to address these capacity issues prior to the proposed development in the area taking place. The remainder of the system is likely to have capacity to accommodate growth up to 6,500 homes.

Within the administrative area of Milton Keynes, extensions have already been carried out under requisition to serve the Wavendon and Eagle Farm sites. However extensions to the Broughton Brook sewer will be required for development within Mid-Bedfordshire.

East Area – North

The initial assessment has shown that the entire system draining the northern part of the eastern study area has sufficient capacity to accommodate growth up to the higher growth target of 6,500 homes. Indeed, from the testing it would appear that there is capacity within the network serving the area for up to 20,500 new homes. Upgrading to inlet works due for completion by March 2009 will greatly improve the capacity situation in the sewer system, particularly in the Broughton Brook area.

Western Area – North

The initial assessment has shown that approximately 40% of the network draining the northern part of the western study area suffers from capacity issues. Works will be required to address these capacity issues prior to the proposed development in the area taking place. Of the remainder of the system, 53% of the system is likely to have capacity to accommodate growth up to 3,500 homes.

AWS are currently appraising the upgrade requirements to serve the Western Expansion Area, it is expected that the area will require new pumping stations and sewers to transfer the point of connection to existing network.

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Western Area – Central

The initial assessment has shown that approximately 22% of the network draining the northern part of the Western Area suffers from capacity issues. Works will be required to address these capacity issues prior to the proposed development in the area taking place. Of the remainder of the system, 65% of the system is likely to have capacity to accommodate growth up to 3,500 homes.

Western Area – South

The initial assessment has shown that the network draining the southern part of the Western Area generally has capacity to service the proposed growth up to the maximum growth targets. The assessments have highlighted that 5% of the network currently has capacity issues; however the majority of the system is likely to accommodate in excess of 3,500 homes.

Northern Area – East

The initial assessment has shown that the network draining the eastern part of the Northern Area generally has capacity to service the proposed growth up to the maximum growth targets. The assessments have highlighted that 25% of the network currently has capacity issues; however 75% of the system would likely be able to accommodate in excess of 1,300 homes.

Although more detailed modelling undertaken by AWS has confirmed that there are no issues in this area. This should be confirmed as part of the detailed study.

Northern Area – West

The initial assessment has shown that the entire system draining the western part of the Northern Area has sufficient capacity to accommodate growth up to 1,300 homes. The pipe with the lowest capacity in the system would likely be able to accommodate the entire growth for the northern development area.

South Western Area

The initial assessment has shown that the entire system draining the South Western Area is likely to have sufficient capacity to accommodate growth up to 9,000 homes. The pipe with the lowest capacity in the system would accommodate growth up to 7,000 homes.

Land East of M1

The initial assessment has shown approximately 67% of the network currently has capacity issues, with only 2% of the network able to accommodate up to 1,500 homes. Major infrastructure upgrades would be required to support the proposed growth.

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Upgrade option would mean have to transfer via the Newport Pagnell system which has capacity issues and also CSO discharges. Almost definitely would be looking at new direct connection to Cotton Valley

Rural Areas – Olney

The wastewater network serving Olney is a pumped system. At this stage it has been assumed that through increasing the pumping rates or pump durations, initial growth in Olney could be handled by the existing system. This would need to be considered in more detail during the detailed stage of the WCS.

In the longer term upgrades to the system may be required.

AWS have confirmed they do not have any model coverage for Olney.

Rural Areas – Hanslope

Initial calculations have shown that there is insufficient capacity in 75% of the network currently serving Hanslope, although this may be exacerbated by missing data (30% of pipes have insufficient data to assess and have therefore been flagged as having incapacity at this stage). Only 15% of the network is shown to have network to facilitate the maximum growth figures for Hanslope.

Therefore further investigation of the wastewater network is required in Hanslope to provide the coverage for the proposed growth.

6.3.2 Wastewater Constraints Summary

The determination of constraints considered for the wastewater network are shown in Table 6-2, with the assessment of the wastewater network summarised in Table 6-3.

Table 6-2: Description of Colouring Assigned to Wastewater Network Constraint Table

Minor constraint (less than 10% of network at capacity)

Significant constraint between 10% and 30% of network at capacity)

Major constraint (more than 30% of network at capacity)

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Table 6-3: Wastewater Network Constraint Assessment Growth Horizon Study Area Existing 1 2 3 4 West - 0-1,200 1,200-2,400 2,400-3,600 3,600-4,800 Central South East - 0-1,200 1,200-2,400 2,400-3,600 3,600-4,800 North East - 0-1,200 1,200-2,400 2,400-3,600 3,600-4,800 North - 0-1,625 1,625-3,250 3,250-4,875 4,875-6,500 Eastern South - 0-1,625 1,625-3,250 3,250-4,875 4,875-6,500 North - 0-875 875-1,750 1,750-2,625 2,625-3,500 Western Central - 0-875 875-1,750 1,750-2,625 2,625-3,500 South - 0-875 875-1,750 1,750-2,625 2,625-3,500 East - 0-375 375-750 750-1125 1125-1,500 Northern West - 0-375 375-750 750-1125 1125-1,500 South Western - 0-2,250 2,250-4,500 4,500-6,750 6,750-9,000 Land East of M1 - 0-1,500 1,500-3,000 3,000-4,500 4,500-6,000 Olney - 0-375 375-750 750-1,125 1,125-1,500 Rural Hanslope - 0-375 375-750 750-1,125 1,125-1,500

6.3.3 Wastewater Network Modelling

The high level assessments have only considered the impacts of development in each of the study areas and sub-areas on an independent basis. Further capacity issues may be highlighted when considering the cumulative effect of drainage systems which join further down the system.

Without more detailed investigation, there is considerable uncertainty to the level of the effects of this potential problem and it is recommended that wastewater modelling is considered (where feasible and model coverage is available) to verify this as part of the detailed WCS.

6.4 Wastewater Environment Baseline

6.4.1 Water Environment Data

The Water Quality assessment has made use of water quality data collected and supplied by the Environment Agency, along with information on the legislation which drives the water quality standards required to protect ecological habitat integrity for the river systems.

The hydraulic capacity has been undertaken at a high level and has compared existing discharges from Cotton Valley and likely increases in discharges with peak flows in the River Ouzel and River Great Ouse.

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Increased effluent discharges to the River Ouzel and River Great Ouse will impact on flood risk and water quality. Before approving increases in consented discharges to these rivers, the EA will require further catchment modelling to identify any necessary mitigation works particularly with reference to the lakes in Milton Keynes. This should either be included in the detailed stage of the water cycle study, the Level 2 SFRA or as an independent study for example a surface water management plan.

In terms of the wider water related environment, the outline WCS has undertaken the initial screening stages of an Appropriate Assessment 10 to identify whether the water cycle and water infrastructure changes assessed in the WCS are likely to have a detrimental impact on the habitats of European designated sites of nature conservation. This screening study undertook a review of all designated sites (European, national and regional/local) that are hydrologically linked to watercourses or aquifers potentially affected by development in Milton Keynes.

At this stage in the WCS assessment, a review of water-related environment baseline with respect to wastewater discharges is essential to ensure that:

• The water related environment has the capacity to absorb further discharges to the receiving watercourse,

• There are no absolute constraints in terms of the water environment baseline (i.e. unacceptable increase in flood risk),

• There is no unacceptable deterioration in the quality of the water related environment.

The assessment of the water environment baseline has considered the capacity issues associated with the ability of receiving watercourses to accept further discharges of treated wastewater from the new development. This assessment has been undertaken for the impacts locally on the river systems, but also on hydrologically linked sites designated for ecological and conservation reasons.

An assessment of the capacity of water resources for further abstraction has been undertaken separately and described in Section 7.

6.5 Water Quality Baseline and Capacity

6.5.1 Water Quality Legislation, Guidelines and Monitoring

There are several Statutory and Guideline documents that are designed to protect water quality and aquatic ecology, ranging from legislation with which to assess pollution from pesticides and other

10 The need for Appropriate Assessment is set out within Article 6 of the EC Habitats Directive 1992, and interpreted into British law by Regulation 48 of the Conservation (Natural Habitats &c) Regulations 1994

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substances, to limits for bacteriological quality of water for bathing and shellfisheries. The most ubiquitous water quality information for surface waters is the EA River Ecosystem (RE) scheme, which is supported by monitoring programmes for basic chemical and biological parameters under the General Quality Assessment Scheme (GQA). An explanation of the RE/GQA scheme is given here, before describing some changes in water monitoring that are being introduced as part of the Water Framework Directive (WFD) implementation in Section 11. To enable ease of comparison, the current water quality of the Rivers Great Ouse and Ouzel is described fully in Section 11.2.1. This is to enable the impact of likely future standards to be assessed easily against existing standards. This introduction is intended to aid the interpretation of water quality data in the Milton Keynes area, and to indicate possible future water quality impacts.

RQO’s are targets used to help protect and improve the quality of the water in watercourses. Each stretch of river is given a target from the EA River Ecosystem Classification scheme. These range from very good quality (suitable for all fish species) to poor quality (likely to limit fish species). If a river achieves this target it means that the river will be of adequate quality to support a certain type of ecosystem. The EA would also be confident that the river would meet the requirements for wildlife, conservation, recreation and abstraction for other purposes.

In terms of chemistry, a suite of eight determinands is used for river quality objectives, but a more limited list of three key determinands is selected for the purpose of compliance trends: biochemical oxygen demand, dissolved oxygen and ammonia. However, the EA recognise that ‘spot’ samples only provide an estimate of the underlying quality of the water being sampled. Therefore, the confidence limits within which the ‘real’ quality is assumed to lie are calculated. The level of confidence chosen for assessment of compliance with river quality objectives is 95%. The chemical determinands are described using the GQA scheme, described below.

6.5.2 Chemical GQA Scheme, Guidelines and Standards

The EA grades the chemical quality of rivers using the GQA scheme, which is designed to provide an accurate and consistent assessment of the state of water quality in rivers over time. Sites are sampled a minimum of 12 times a year for determinands shown in Table 6-4. The EA uses the data collected over three years because this produces 36 samples per site, giving the required precision in making judgments about particular rivers from point sources of pollution, balanced against the cost of monitoring and resources needed for water quality sampling.

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Table 6-4: Environment Agency chemical GQA grades in watercourses

mg N L-1 Dissolved Oxygen BOD Ammonia -1 -1 90 percentileGQA (% saturation) mg Lmgl mgNl grade 10 percentile 90 percentile 90 percentile A 80 2.5 0.25 B 70 4 0.6 C 60 6 1.3 D 50 8 2.5 E 20 15 9.0 F <20 >15 >9.0

The overall scheme also includes a biological assessment, in which macroinvertebrates in the river are compared with the likely assemblage if the river was not impacted, and assigned a grade (Table 6-5). Flow and morphology are taken into account. Two biological samples are collected, one in spring (March to May) and one in autumn (September to November). Complete national surveys were carried out in 1990, 1995 and 2002. From 2002 the EA began to sample one third of sites each year, so that every site is sampled once in three years. The reported results use the most recent data at each sampling site.

Table 6-5: Biological Monitoring Grades Classification Description A – very good Biology similar to that expected for an unpolluted river B – good Biology is a little short of an unpolluted river C – fairly good Biology worse than expected for unpolluted river D – fair A range of pollution tolerant species present E – poor Biology restricted to pollution tolerant species F – bad Biology limited to a small number of species very tolerant of pollution

The routine EA samples are not flow-based, and have historically been collected primarily to support monitoring of point-source emissions to water, such as WwTWs. Thus, storm events, which drive most diffuse pollutant transport mechanisms, are not specifically sampled, and the concentrations reported will be a gross underestimate of the peak, albeit usually transient, concentrations. Approximately 90% of diffuse water pollution will occur during high flow following intense or prolonged rainfall and these periods can impact water quality to the detriment of river health, or raw-water abstracted for potable treatment. However, these events are rarely captured by routine monitoring programmes.

Flow-based monitoring to fully assess water quality in watercourses during storm events at sufficient temporal and spatial resolution is resource intensive and is currently not practiced on a routine basis. However, advances in monitoring equipment are changing the nature of water quality monitoring.

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Investigative monitoring for selected water quality determinands can be conducted using auto samplers, semi-continuous water quality probes or a combination of both.

6.5.3 Nutrients

The two most important nutrients in terms of eutrophication, nitrogen (N) and phosphorus (P) are assessed using a separate GQA to other chemical parameters. Table 6-6 shows the GQA Grades for these nutrients used by the EA.

Table 6-6: Environment Agency nutrient GQA grades Classification for Grade limit Description phosphate (mgP/I) average 1 0.02 Very low 2 0.06 Low 3 0.1 Moderate 4 0.2 High 5 1.0 Very high 6 >1.0 Excessively high Grade limit Classification for nitrate Description (mg NO3/I) average 1 5 Very low 2 10 Low 3 20 Moderately low 4 30 Moderate 5 40 High 6 >40 Very high

Of all forms of P, it is desirable to determine the concentrations of Soluble Reactive Phosphorus (SRP) as this form of P is most immediately available to aquatic macrophytes and algae. Phosphorus is usually the limiting nutrient in inland freshwaters and gives an indication of the likelihood of eutrophication within a water environment. There are guidelines on concentrations that should occur to protect the overall health of the waterbody, as shown in Table 6-7. Some sources of P to waterbodies are regulated by legislation, such as discharges from WwTWs (Urban Wastewater Treatment Directive, (91/271/EEC).

The Urban Waste Water Treatment Directive (UWWTD) was agreed in 1991. The UWWTD has requirements for sewerage collection and sets standards for sewage treatment. The general principle of the Directive is to provide treatment of sewage from the largest discharges first, and to protect sensitive waters. Areas are designated under the Directive according to three criteria: (a) waters that are, or have the potential to become, eutrophic if no protective action is taken. (b) drinking water sources that contain or

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could contain more than 50mg/l of nitrate if no protective action is taken. (c) waters in need of protective action to meet the requirements of other Directives. Waste water discharges over 10,000 PE that discharge to Sensitive Areas need treatment that relates to the designation criterion or criteria as outlined in Table 6-7.

Currently in the Milton Keynes study area, although the Rivers Ouse and Ouzel are designated Sensitive under the UWWTD, only Cotton Valley WwTW has a PE sufficient to qualify under the legislation. However, to consider the water environment effectively, a catchment approach should be considered. There are several WwTWs upstream of Milton Keynes e.g. Dunstable, Leighton Linslade and Buckingham, and these should also be considered in any more detailed analysis of water quality. All of these works are over 10,000 PE and therefore have target concentrations of total phosphorus of 2.0 mg/l, as shown in Table 6-7.

Table 6-7: Provisions for Sensitive Areas under the UWWTD

Total nitrogen Concentration (mg/l) Reduction (%)

10,000 to 100,000 PE 15 >100,000 PE 10 70-80 Total phosphorus Concentration (mg/l) Reduction (%) 10,000 to 100,000 PE 2 >100,000 PE 1 80

By contrast to phosphorus, concentrations of nitrogen in inland waterbodies, in the form of nitrate (expressed as either NO3 or NO3-N), are directly affected by legislation. The EC Nitrates Directive 91/676/EEC aims to reduce nitrate pollution from agriculture and there is legislation to regulate the amount of NO3 emissions to water from point sources, such as WwTW’s. The objective is to reduce the problem of eutrophication in surface waters and to limit the concentration of nitrate in drinking water from both ground and surface water. The Directive does not itself set mandatory standards but relies on other legislation. The Surface Water Directive, 75/440/EEC, specifies a mandatory limit of 11.3 mg/l NO3-N (50 mg/l NO3), while the Drinking Water Directive, 80/778/EEC, sets the same mandatory value for human consumption via water.

6.4.2 Relationship between River Ecosystem RQO and GQA grades

Compliance with the RQO is assessed on a 3 year rolling basis from the GQA routine monitoring undertaken by the Environment Agency. Although methods of calculation and standards are not identical, GQA Grade A is approximately equivalent to RE1 etc, as shown in Table 6-8.

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Table 6-8: Relationship between GQA and RQO/RE Grades

GQA RQO (RE) Ecological Status A RE1 Excellent B RE2 Good C RE3 Moderate D RE4 Poor E RE5 Unsuitable

6.5.4 Sediment

Sediment is especially important in the water environment, yet it can be complicated to assess. The Freshwater Fish Directive (78/659/EEC) gives a guideline value of 25 mg/l for suspended sediment in rivers for salmonid fisheries. The concentrations of suspended sediment in streamflow are directly related to velocity and available substrate for suspension. Sediment may be re-suspended from the stream-bed, or derived directly from soil erosion during rainfall. Suspended sediment can cause several direct problems, such as reduce light penetration affecting photosynthesis or siltation of spawning gravels, as well as carrying adsorbed substances such as P, metals or sediment bound pesticides, such as the insecticide cypermethrin.

The type of standard set in the Freshwater Fish Directive, as an annual mean concentration, is almost meaningless for sediment management in the context of the achievement of ecological objectives because of the aforementioned spatial and temporal variability of sediment, and the need to identify issues of excess (and deficit of) sediment. It is also not the most appropriate for tackling sediment pollution problems such as those caused by occasional events; for example diffuse pollution from land during storm events. Therefore, Casper and Jensen (2007), consider there is a dual need; for standards that tackle sediment as a diffuse pollution issue and define conditions for good sediment habitat supportive of ecological objectives, and a regime that can also manage specific risks. Accordingly, Natural England recommends that different river types need different sediment levels for effective ecological functioning.

6.5.5 Receiving Watercourse - Baseline and Capacity

The River Ouzel is heavily engineered and it is likely that any increase in discharges from Cotton Valley as a consequence of the proposed development within Milton Keynes would not have a detrimental effect in terms of capacity.

However the River Ouzel discharges to the River Great Ouse at Newport Pagnell and the EA have expressed concerns about the increased risk of flooding at Newport Pagnell as a result in an increase in discharge from Cotton Valley.

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The EA have confirmed that they would not wish to see any net increase in discharges, which would increase flood risk at Newport Pagnell. Increased effluent discharges to the River Ouzel and River Great Ouse would impact on flood risk and water quality. Before approving increases in consented discharges to these rivers, the EA will require further catchment modelling to identify any necessary mitigation works particularly with reference to the lakes in Milton Keynes. This should either be included in the detailed stage of the water cycle study, the Level 2 SFRA or as an independent study for example a surface water management plan.

For water quality, the EA position has been that any increase in flows from WwTWs that occur as a result of growth must comply with their policy on No Deterioration. This requires that increases in failure of a mandatory standard caused by growth should be offset by reducing the consent limits of the associated discharge(s). The policy allows the EA to impose consent limits up to the limit of “best available technology not entailing excessive cost” (BATNEEC). It also allows the EA to make special justification for imposing consent limits more stringent than BATNEEC.

An initial estimation of peak flood flows for both the River Ouzel (at the Cotton Valley discharge location) and River Great Ouse (immediately downstream of confluence with the River Ouzel) have been undertaken using the Flood Estimation Handbook (FEH) Statistical Method and Revitalised Flood Hydrograph (ReFH) Method, these are shown in Table 6-9. These independently derived flows should be compared against any available existing data (i.e. EA models).

Table 6-9: River Ouzel - Peak Flow Estimates Peak flows Event Return Period FEH Statistical ReFH 95% Exceedance (Q95)* 0.47 m 3s-1 Mean Flow* 2.03 m 3s-1 10% Exceedance (Q10)* 4.47 m 3s-1 2 year 26.2 m 3s-1 35.0 m 3s-1 10 year 44.6 m 3s-1 51.5 m 3s-1 50 year 61.4 m 3s-1 69.4 m 3s-1 100 year 69.1 m 3s-1 79.7 m 3s-1 100 year plus climate change 82.9 m 3s-1 95.6 m 3s-1 1000 year 98.2 m 3s-1 135.2 m 3s-1 * Information from gauging station data on www.nwl.ac.uk for River (Bedford) Ouse at Newport Pagnell (33037)

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Table 6-10: River Great Ouse - Peak Flow Estimates Peak flows Event Return Period FEH Statistical ReFH 95% Exceedance (Q95)** 0.39 m 3s-1 Mean Flow** 4.41 m 3s-1 10% Exceedance (Q10)** 11.11 m 3s-1 2 year 91.6 m 3s-1 128.9 m 3s-1 10 year 148.3 m 3s-1 185.1 m 3s-1 50 year 205.4 m 3s-1 243.5 m 3s-1 100 year 233.2 m 3s-1 276.5 m 3s-1 100 year plus climate change 279.9 m 3s-1 331.8 m 3s-1 1000 year 346.3 m 3s-1 449.4 m 3s-1

** Information from gauging station data on www.nwl.ac.uk for River Ouzel at Willen (33015)

The current estimated DWF from Cotton Valley WwTW as provided by AWS is 78,000 m 3d-1, which equates to a flow rate of 0.90 m3s-1. An initial estimate of the increase in DWF, post development in Milton Keynes (considering the highest growth estimates) has shown an increase of 0.36 m3s-1.

The increase in DWF equates to 8% of the mean flow within the River Great Ouse and 18% of the mean flow in the River Ouzel. During flood events, the increase in DWF equates to 0.15% of the estimated 1 in 100 year flow in the River Great Ouse and 0.52% of the 1 in 100 year flow in the River Ouzel (based on FEH statistical flow estimates). The detailed WCS should consider the effects of these increased flows in more detail. This may include re-running of existing hydraulic models.

6.5.6 Habitats Regulation Assessment

The initial stages (screening stages) of a Habitats Regulation Assessment as required under the Habitats Directive have been undertaken for the outline WCS (Section 10). Until the development areas and development scenarios are agreed in detail following review of all planning considerations, it is not possible to complete a full “Appropriate Assessment” (AA) on the WCS to determine the full impact on designated European Sites (such as SACs, SPAs or RAMSAR sites). This will be a requirement of the detailed WCS, but a screening study for the AA is suitable for the outline WCS in order to identify if they are any ecological constraints to the outline study.

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6.6 Wastewater Summary

In summary, the following general points can be made about the wastewater baseline and spare capacity:

• Additional wastewater flow from the Central Area and immediate environs will be transferred and treated at Cotton Valley WwTW,

• Additional wastewater flow from Olney and Hanslope may be transferred and treated at Olney WwTW and Hanslope WwTW respectively, however there are issues relating to the network and treatment capacities for both systems,

• There is sufficient volumetric headroom treatment capacity at Cotton Valley to treat an estimated 55,560 homes,

• There is no consented flow headroom at Olney WwTW.

6.6.1 Key Network Constraints

• Upgrading to inlet works due for completion by March 2009 will improve the capacity situation in the sewer system, particularly to the east (Broughton Brook trunk sewer),

• There is sufficient volumetric treatment headroom at Hanslope WwTW to enable connection of an estimated 755 homes,

• High level assessments have shown that there are a number of both existing and potential wastewater network issues, that will need examining in more detail during the detailed WCS,

• The network conclusions need to be verified with network modelling of the development scenarios.

A summary of the wastewater network capacity is shown in Table 6-11.

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Table 6-11: Wastewater Network – Constraints Summary Study Area Sub Area Constraint North East Major Central South East Significant West Significant South Major Eastern North Minor North Major Western Central Significant South Minor East Significant Northern West Minor South Western Minor Land East of M1 Major Olney Major Rural Hanslope Major

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7 Water Resources and Supply Baseline

7.1 Introduction

This assessment covers the existing baseline with respect to available water resources and where the raw water to supply the new development will be sourced. It also considers the requirement for transmission infrastructure for treated water in order to service and supply the new development areas.

7.2 Available Data and Assumptions

Water supply to Milton Keynes is the sole responsibility of AWS who are in the process of producing their statutory Water Resource Management Plan (WRMP) 2009 which sets out how AWS plan to provide the required water resources for the region over the next 25 years (from 2010 to 2035). Some outline interim information was made available from the emerging plan in terms of forecasted supply and demand balances to 2021 and beyond. The draft WRMP09 was due for consultation at the time of writing this draft report and hence was not available for the Outline Study; however, the following information was made available:

• AWS have made available their 2004 WRMP which has been used in this assessment,

• Some outline information was made available in terms of supply and demand balance from the draft 2009 WRMP,

• AWS provided network layouts including pipe sizes of the water supply network,

• EA Upper Ouse and Bedford Ouse Catchment Abstraction Management Strategy (CAMS).

The final WRMP09 is to be published in 2009 and further details of this will be included in Stage 2 of WCS, if this information is available.

Consultation with AWS confirmed that they hold no DG2 records for Milton Keynes.

7.3 Regional Water Resources: Existing Situation

The EA identifies the Anglian Region as being the driest region of England and Wales. On average the region receives just less than 600 mm of rainfall per annum

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Evaporation from vegetation reduces this amount by approximately 450 mm a year, to give only 150 mm per annum of ‘effective rainfall’ 11 to replenish aquifers and to maintain river flows. The recharge of aquifers is an important mechanism for providing feeds to groundwater-fed ecosystems and wetland habitats. This is aligned with the government policy to maximise SUDS where possible and practical.

In drought years, the rainfall across the Anglian Region can be as low as 450 mm, which reduces the amount of ‘effective rainfall’ to zero. The climate gradient from West to East and from North to South is accentuated across the region.

Regionally, the water supply is resourced from two main sources:

• Surface water abstraction (rivers and reservoirs) – 60%,

• Groundwater abstraction – 40%.

7.4 Milton Keynes - Water Resource Baseline Assessment

The EA manages water resources at the local level through the use of Catchment Abstraction Management Strategy (CAMS) and Milton Keynes lies within the boundary of the River Great Ouse catchment. The particular CAMS document referred to in the main is the Upper Ouse and Bedford Ouse CAMS, published in March 2005.

Within the CAMS, the EA’s assessment of the availability of water resources is based on a classification system that gives a resource availability status and indicates:

• The relative balance between the environmental requirements for water and how much is licensed for abstraction,

• Whether water is available for further abstraction,

• Areas where abstraction needs to be reduced.

The categories of resource availability status are shown in Table 7-1. The classification is based on an assessment of a river system’s ecological sensitivity to abstraction-related flow reduction. This classification can then be used to assess the potential for additional water resource abstractions.

11 Effective rainfall is defined as the proportion of rainfall that makes up flow river flow or aquifer recharge i.e. that which is not lost to evaporation, uptake by plants or soil storage

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Table 7-1 CAMS resource availability status categories Water is likely to be available at all flows including low Water Available (WA) flows. Restrictions may apply. No water is available for further licensing at low flows. No Water Available (NWA) Water may be available at higher flows with appropriate restrictions. Current actual abstraction is such that no water is available at low flows. If existing licences were used to Over Licensed (O-L) their full allocation they could cause unacceptable environmental damage at low flows. Water may be available at high flows, with appropriate restrictions. Existing abstraction is causing unacceptable damage to Over Abstracted (O-A) the environment at low flows. Water may still be available at high flows, with appropriate restrictions. The classification for each of the surface waters and groundwater catchments around Milton Keynes is summarised in Table 7-2.

Table 7-2 : CAMS resource availability classification Water Resources Management Unit Surface Water Groundwater 8 - River Ouzel NWA NWA 10 - Upper Great Ouse NWA NWA 9 - Broughton Brook O-A O-A 4 - Bedford Great Ouse NWA NWA

The River Ouzel and Broughton Brook are fed from the Lower Chalk and Lower Greensand Formations, and then flow in a southeast-northwest direction to join the River Upper Great Ouse near Newport Pagnell.

The River Upper Great Ouse rises further to the west in the Great Oolite Formation and flows in a southwest-northeast direction along the line of the Great Oolite outcrop. A sharp bend in the Great Ouse occurs north of Bedford and results in the river turning south for a short stretch until it reaches Bedford, after which the river continues to flow eastwards across the Oxford Clay. During this short stretch north of Bedford, the river flows across both the Cornbrash and Kellaways Beds Formation which are exposed in this section.

A majority of the rivers (including the River Ouzel and River Great Ouse) are defined as having no water available (NWA) at least at times of low flows. This condition applies to both the surface and groundwater resource assessments of these catchments. The position of these rivers and groundwaters is that at times of low flows, no new licences are likely to be issued by the EA unless an equivalent resource is given up elsewhere. The situation with regards the issuing of abstraction licences at times of higher flows will be subject to review on a case by case basis.

The situation for the Broughton Brook catchment is that a number of large groundwater abstraction licences from the Lower Greensand Formation mean that this catchment is classed as being over abstracted (O-A). No further details have been provided on these abstraction licences and percentage

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use. Given this classification, no new abstraction licences are likely to be issued until the resource position has eased.

7.4.1 Abstraction sources

Milton Keynes (current population approximately 200,000) is situated within AWS Ruthamford Water Resource Zone 11 (WRZ 11). The name for this zone comes from the three major strategic reservoirs which supply it, namely Rutland Water (Rut-), Grafham Water (-ham-) and Pitsford Water (-ford). Milton Keynes gets its supply from Rutland Water and Grafham Water. These are pumped storage reservoirs with long retention periods and receive most of their throughput from water abstracted from the Rivers Nene (Rutland) and Great Ouse (Grafham). These reservoirs are both situated some distance from Milton Keynes. Despite this distance, these sources provide a majority of the supply to Milton Keynes. Extra water from these sources will be required to meet the future needs of an expanded Milton Keynes.

Closer to Milton Keynes are a number of groundwater sources around Woburn which abstract water from the Lower Greensand Formation (Woburn Sands). Boreholes are located at Birchmoor-Aspley Guise (Birchmoor WTW) and at Sandhouse (which is also the name given to the works). Details of average licence and its Deployable Output 12 (DO) indicate that this licence is already maximised [information from AWS 2004 WRMP,] Table 7-3. The 2004 WRMP refers to some of these sources suffering from rising nitrate concentrations, which will require action in the future.

A small surface water source (Foxcote intake and reservoir) lies close to Milton Keynes (approximately 12 km to the west) and was last used in 1994. This type of licence, often known as a ‘sleeper licence’, could potentially be brought back into use given appropriate investment.

In addition, there are other surface water resources in Bedford, which is supplied by Clapham WTW (approximately 20 km away from Milton Keynes). This WTW abstracts from both surface water (River Great Ouse) and from groundwater. The average licensed abstraction rates from these two sources are 27 and 6 Ml/d respectively (Table 7-3). This compares to a combined (DO) figure from the 2004 WRMP of only 15 Ml/d. The 2004 WRMP refers to this source suffering from significant outages (losses) at times of higher flows. By using surface water and groundwater sources conjunctively, it may be possible to overcome some of these problems given appropriate investment.

The strategic reservoirs of the Ruthamford WRZ-11 also provide long-standing bulk transfers to Three Valleys Water Company from Grafham Water and to Severn Trent Water from Rutland Water via Wing WTW. There is also a small indirect supply to Thames Water’s supply area in the Aylesbury Vale, the connection taking place via Shenley Water Booster (WB) and Mursley Water Reservoir (WR) to the south of Milton Keynes.

12 DO is, water which is available for supply during dry years

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Table 7-3 : Extracts from AWS 2004 WRMP WTWs Source Type Average Licence (Ml/d) 2004 WRMP DO (Ml/d) Clapham WTW Surface Water Intake 1 + wells 27 + 6 15 Foxcote WTW Surface Water Intake/ reservoir 2 9 + 9 0 Birchmoor 3 Boreholes 7 6 WTW Sandhouse Boreholes 5 4 WTW 4 1 River Bedford Great Ouse, d/s of Milton Keynes (Cotton Valley). Significant Outage (e.g. loss in DO) at high flows 2 Foxcote WTW closed in 1994 (AMP2) 3 Birchmoor WTW – groundwater fed WTW known to suffer from high nitrate concentrations 4 Sandhouse WTW – groundwater fed WTW which will feed the proposed Newton Leys development (pers. comm. AWS)

7.5 Water Supply – Existing Capacity 7.5.1 Growth Forecasts – Increase in demand

The growth forecasts for Milton Keynes refer to the need for approximately 57,950 new homes by 2026. In terms of population, this represents an increase of approximately 132,700 or 66% increase (assuming an occupancy of 2.29) on the existing 200,000 residential population of the city.

Various estimates can be made of the likely increase in residential demand expected from the developments around Milton Keynes based on the overall growth targets and the development scenarios as set out in earlier sections. The highest forecast for the demand from the maximum target of 57,950 new homes is 19.46 Ml/d to be supplied on average by AWS. At the other end of the range of estimates, the lowest demand is 15.99 Ml/d. Tables 7-4 and 7-5 also give an indication of the most likely demand scenario, assuming that new homes use on average 128 l/h/d and occupancy rates of 2.3, giving a total average usage of water for 57,950 new homes of 16.99 Ml/d. If an allowance is made for leakage, WTW operational usage and outage (loss of yield), then up to 30% could be added to these figures. In addition to the increased residential demand, the growth of the city will also generate an increase in growth in non- residential development. In the case of Milton Keynes, the non-residential development is likely to be mainly commercial i.e. shops and service based industry (Halcrow 2007). These industries are likely to serve the needs of local communities and as such it has been assumed that there will be some form of relationship between the growth in residential and non-residential demand.

In order to estimate the non-residential demand , the approach taken here has been based on information provided from the OFWAT Security of supply, leakage and water efficiency reports (in both 2005-06 and 2006-07). Data from these reports shows that non-household demand ranged consistently from 51 to 53% of total metered demand and to be <1% of total unmetered demand in both years (based on AWS data).

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In the case of these non-residential demands), the AWS forecast (new) for residential have been used as the basis for estimating the non-residential demand. As the <1% figure of total unmetered demand is so small, then this has been ignored for these calculations.

This total estimated demand figure for non-residential demand (9.14 Ml/d) has been apportioned to individual areas based on their proportional area as part of the total non-residential development area.

These values have been combined together with residential demand to give a total demand figure (both residential and non-residential).

The estimates range from 25.1 to 28.6 Ml/d, with the most likely demand figure being around 26 Ml/d. Note this figure does not include the 30% allowance for headroom referred to above.

One issue which has not been considered in great detail is the potential Marston Vale Eco-Town. If the Eco-town were to go ahead within a similar time-frame to the developments in Milton Keynes, then this could add an extra 6 Ml/d of demand on to the demand figures given in Table 7-4 and Table 7-5.

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Table: 7-4 Residential Water Demand Range of Range of Eco–homes Eco–homes rating Eco–homes rating AWS forecast Estimates Estimates Study Area Nos. homes *1 rating 120 l/h.d 135 l/h.d 127.5 l/h.d (Ml/d) *2 *2 *2 Min Max (Ml/d) (Ml/d) (Ml/d) (Ml/d) (Ml/d) Central 14350 4.82 3.96 4.46 4.21 3.96 4.82 Eastern (inc. 5,600 Mid- 13000 4.37 3.59 4.04 3.81 3.59 4.37 Beds) South Western (inc. 9000 3.02 2.48 2.79 2.64 2.48 3.02 5,390 in Aylesbury Vale) Western 10000 3.36 2.76 3.11 2.93 2.76 3.36 Northern 3000 1.01 0.83 0.93 0.88 0.83 1.01 Outliers (Olney, Hanslope 3000 1.01 0.83 0.93 0.88 0.83 1.01 & Newport Pagnell) Land East of M1 5600 1.88 1.55 1.74 1.64 1.55 1.88 Total 57950 19.46 15.99 17.99 16.99 15.99 19.46

*1 Assuming 146 l/h.d supplied and assuming occupancy rate 2.3 (estimate used for Thetford WCS) *2 Eco-homes rating of 120-135 l/h/d (Ref. Consultation of water efficiency in new buildings, CLG – January 2007) and an assuming occupancy rate of 2.3 (AWS Strategic Doc. – Dec 2007)

Final December 2008 67 Milton Keynes Council Water Cycle Study – Outline Strategy Table 7-5: Total Water Demand in Milton Keynes Weighting based on Total Supply Range of Development area Range of Estimate of Water development area (Residential & Non- Estimates Study Area Nos. homes *4 (Non-residential) Estimates Min to be supplied (Non-residential) residential) Max Ha (Ml/d) (Ml/d) (Ml/d) Central 14350 - 86 4.52 8.72 8.48 9.33 Eastern (inc. 5,600 Mid- 13000 2.78 6.60 6.37 7.15 - 53 Beds) South Western (inc. 5,390 9000 0.16 2.80 2.64 3.18 - 3 in Aylesbury Vale) Western 10000 - 29 1.52 4.46 4.28 4.88 Northern 3000 - 3 0.16 1.04 0.99 1.16 Outliers (Olney, Hanslope 3000 0.01 0.89 0.83 1.01 - 0.1 & Newport Pagnell) Land East of M1 *5 5600 1.64 1.55 1.88 Total 57950 9.14 174.1 9.14 26.13 25.14 28.60

*4 Non-residential demand assuming MK similar to the rest of AW Region i.e. average 52% over the last 2 years of total metered supply. Note demand estimated on AWS forecast 5 No non-residential development assumed to take place on land east of M1

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7.5.2 Existing Capacity

Milton Keynes lies within AWS’s Ruthamford Water Resource Zone (WRZ –11). The definition of a WRZ is the largest supply area in which water resources can be readily moved about and shared. Exports and imports may also take place from these zones.

The Ruthamford WRZ is one of the largest WRZs in the Anglian region, extending from Peterborough in the north to Buckingham and Leighton Buzzard in the south. It also serves the growth town of Corby.

For each of these WRZs, AWS is required to carry out an assessment of how much water is available and how much water may be required in the future. This balance is called the supply and demand balance (S/D balance) and it is calculated for the current baseline and projected forward 25 years (to 2035) such that AWS can determine where future deficits in the balance might occur (or are already occurring); this planning is undertaken for a worst case very dry year to ensure that sufficient resources are available for worst case conditions. The projected future demand includes for estimates of increases in population for the Milton Keynes and Newport Pagnell Water Resource Planning Zone (WRPZ) and includes an allowance for ‘headroom’ on top of the future predicted demand. The headroom allows for issues such as outage of water supply facilities and an allowance for uncertainty associated with climate change.

The 2004 WRMP provides useful background information on the Ruthamford WRZ. A brief summary of the zone’s water balance is given below:

• Total DO from the Ruthamford WRZ-11 is between 582 (average) and 732 (peak) Ml/d,

• AWS Distribution Input (DI) 13 figure range from between 361 (average) and 510 (peak) Ml/d,

• The difference is made up of mainly exports from this zone, including long-standing bulk transfer agreements with both Three Valleys Water Company (91 Ml/d on average from Grafham WTW to the south) and Severn Trent Water (18 Ml/d on average from Rutland/Wing WTW to the west),

• The remainder is made up of leakage (approx. 81 Ml/d in this zone or 22% of average DI) and a small amount of both WTW operational usage and outage (loss of yield) etc,

• AWS leakage is close to Economic Level of Leakage 14 (ELL) for this zone of 77 Ml/d. It was planned to keep close to the ELL throughout the AMP4 period (2005-2010). Further discussion on AWS Water Efficiency Strategy is included in section 7.5.5.

Overall, the position up to 2010 was that a slight deficit in the supply/demand balance for this zone was expected.

13 Distribution input – The amount of water put into supply, including water not actually delivered i.e. leakage and water taken illegally. 14 Economic Level of Leakage - The level of leakage for which the cost of achieving and then maintaining that level is exactly offset by savings in capital and operating costs.

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A detailed water balance for Milton Keynes (including Newport Pagnell) has been provided by AWS, as an interim output ahead of the 2009 draft WRMP which is due to be published in May 2008. The information provided at present includes details of the amount of water available for supply and the demand for potable water in the Milton Keynes and Newport Pagnell Water Resource Planning Zone (AWS’s WRPZ No. 93 and 92 respectively). The WRMP process then identifies potential water resources that could be developed to bridge the gap in supply and demand (covered in Section 8 – future water supply strategy). The latest interim S/D balance provided by AWS indicates that:

• The current predicted average demand in Milton Keynes and Newport Pagnell is around 55 Mld -1 and just over 60 Mld -1 with an allowance for headroom,

• The average demand is projected to increase by around 5 Mld -1 by 2035; the allowance for headroom results in an increase in demand of around 14 Mld -1 by 2035 (N.B. the differences between this figure and estimates made in Tables 7-4 and 7-5 may be due to different assumptions made on the number of new homes to be built. Potential inconsistencies to be looked during the detailed study.

The Milton Keynes and Newport Pagnell WRPZ currently only has sufficient DO to meet demand, not taking into account headroom, through until 2019/20. If headroom is taken into account, then there is already a shortfall in the existing resource position and therefore further development of new resources will be required immediately. In order to address this position AWS will be undertaking upgrading work at Wing WTW to increase the DO within the AMP4 period (2005-2010). Beyond 2010, then the supplementing of available resources by developments of local resources within existing abstraction licence limits may be necessary.

The interim outputs from 2009 draft WRMP demonstrates the importance for AWS of completing their investment plans for AMP4 period. The upgrading of Wing WTW was seen by AWS as the medium term solution (covering the period up to around 2021) in their 2004 WRMP. The scheme will enable AWS to maximise their abstraction licence at Rutland Water. More specifically the scheme will see;

• An increase in the design capacity of Wing WTW from 270 to 360 Ml/d (currently the average and peak DO figures are 204 and 255 Ml/d respectively),

• The provision of 40 km of large diameter trunk main from Rutland Water to Wing WTW and from there to Kettering (approximately half-way to Milton Keynes) via Corby,

• The provision of associated pumping stations for this trunk main.

This work is due for completion by March 2010.

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It is expected that the 2009 draft WRMP will contain updates on these schemes and other planned work for the Ruthamford WRZ-11 underway during AMP4.

7.5.3 Environmental Baseline - Water Supply Assessment

Wing WTW is operated in conjunction with Rutland Water. This reservoir was originally constructed in 1975, and shortly after it was designated as both a SSSI and Special Protection Area (SPA), the latter being in recognition of its standing as an internationally important wetland habitat for migrating birds.

The Statutory Designations at Rutland Water mean that any potential impacts have to be assessed and mitigated where necessary. The approval by the Secretary of State for the planning permission associated with Wing WTW, place a requirement on AWS to undertake mitigation measures to overcome the impacts on wildlife in the event of the reservoir being drawn down for longer periods than at present. The measures proposed have included the construction of dams across parts of reservoir to form lagoons and wetlands, mainly along the western edge of the reservoir. The new wetlands will be completed by November 2010 (the construction taking slightly longer than at Wing WTW in order to minimise the adverse effect on the SPA. Work is being conducted mainly in late-winter, spring and early summer for the next three years).

Long term management and maintenance of these newly created wetlands is still to be agreed, although AWS have confirmed that they are near to completing their consultation and hope to reach agreement with the various parties shortly.

The extra length of time during which Rutland Water is drawn down, may have consequences on the amount of spill which takes place from this reservoir and flows into the Rivers Gwash and Welland. Although it is worth mentioning that the extra demand placed on Rutland Water from growth in Milton Keynes will be small compared to the total growth expected across the wider East of England.

A number of other protected sites are mentioned in the CAMS document. A summary of the protected sites within certain catchments are presented in Table 7-6.

Table 7-6: Summary of Protected sites Water Resources Distance and direction Protected areas/ SSSI WTWs Management Unit from CMK (WRMU) 4 – Bedford Great Ouse Clapham 20km - North East See paragraph below

Foxcote Res & Wood, 10 – Upper Great Ouse Foxcote 12km - West Tingewick Meadows 9 – Broughton Brook Birchmoor 5km - East Wavendon Heath Ponds

Note: County Wildlife Sites have not been included in this table

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2004 WRMP (public version) makes reference to a number of historical concerns by stakeholders about the Bedford Great Ouse (from which abstractions take place at Clapham WTW) and Nene (abstractions for Peterborough area) but which have now been allayed through studies undertaken in the AMP3 period (2000-05).

7.5.4 Potential Risks to Supply

When considering potential risks to AWS supplies, the following points may be important:

• Climate Change – AWS will be considering the effects of climate change in its 2009 draft WRMP. In general the effects on DO from groundwater sources is thought to be negligible. Surface waters are likely to be more affected. For example, surface water intakes such as Clapham WTW (Bedford Great Ouse) could see a loss of yield of up to 2 Ml/d 15 on average. This compares with 2004 WRMP DO figure of 15 Ml/d and which could mean a loss of yield of around 10% by 2021. In the case of the other surface water sources within the Ruthamford system, these are mainly multi-season reservoirs with pumped storage schemes, which rely on abstraction from rivers over the winter months and therefore these are likely to be less affected by climate change,

• Review of Consents – relates to investigations of abstractions and their impacts on designated sites. The EA is the Competent Authority and review is due for completion by 2010. It is currently understood that none of AWS’s sources in the Milton Keynes are part of this review,

• Water Framework Directive – requires all river basins to achieve “good ecological and good chemical status” by 2015. As per the Review of Consents, the EA is the Competent Authority and further details on the Programme of Measures (POM) i.e. actions required to reach Good Ecological Status is expected by the end of 2008. The POM is likely to include details of the further investigations to be undertaken by water companies to ascertain whether any impacts are taking place. These will need to carried out by 2015, with any changes to abstraction licences taking place after this date,

• Water Supply Resilience – all new (and existing) water supplies should be resilient, whereby if the standard means of water provision is disrupted (i.e. the wash out of a pipe across a river crossing) then there is a secondary means to continue to supply potable water. Generally speaking the Milton Keynes water supply system is well connected, allowing the re-distribution of potable water. This is something that must be carried through to any new development.

15 The loss of yield figure of <2 Ml/d was provided by AWS for the Norwich WCS Stage 2

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7.5.5 Water Efficiency Strategy

A water efficiency strategy has been published by AWS within the AMP4 period (2005-2010). This strategy summarises the steps being taken to control the growth in demand. The two main strands of the policy are through leakage control (the latter being achieved through both pressure reduction and checks on pipes) and water metering.

The latest information on leakage from the OFWAT Security of supply report for 2006/07 is that AWS leakage was 202 Ml/d or 17.5% of the DI figure (1156 Ml/d in 2006/07). This figure is below the target set by OFWAT for this year of 215 Ml/d.

AWS has already taken steps to encourage the greater uptake of meters through an initiative in the early 1990’s. Currently around 60% of AWS’s customers have a meter installed. AWS have confirmed that all new connections shall be metered.

In terms of the typical amounts of water used, see Table 7-7.

Table 7-7: Amount of Water Used by Type

2005-06 report 2006-07 report Customer type (l/h/d) (l/h/d) Metered 128.0 136.9 Un-metered 160.0 155.8 Overall 144.0 146.0 Note: 2005/06 and 2006/07 refer to OFWAT Security of Supply report (previously Security of supply, leakage and water efficiency report). An interesting feature of the 2006/07 figures is the slight increase in the water used by AWS metered customers. A full explanation for this increase is to be sought from AWS but it is worth mentioning that this increase was from the very low base apparently observed in 2005/06 (certainly compared with the water industry average for metered customers in 2005/06 of 134 l/h/d). It is therefore possible that AWS underestimated water use in the 2005/06 survey.

7.6 Water Supply Network – Baseline

Assuming that water resource issues can be overcome (especially demand shortfalls, but ideally headroom as well) with upgrading of Wing WTW, it is important to consider how potable water will be supplied to the proposed development areas according to the development scenarios being considered.

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Figure 7-2: High level Milton Keynes Water Supply Schematic Source: Anglian Water Services

Final December 2008 74 Milton Keynes Council Water Cycle Study – Outline Strategy

The existing AWS water supply network within Milton Keynes is shown in Figure 7-1. Figure 7-2 shows the strategic regional water resources distribution network. Figure 7-2 also shows in more detail the water supply system consisting of major trunk mains to transfer water from the various raw water sources to demand centres within Milton Keynes. The main features of water supply network are:

• Imports from Wing WTW (Rutland Water) into the northwest corner of city via the Old Stratford Water Booster (WB),

• Imports from Grafham WTW (from its namesake reservoir) into the east of the city via Woburn Sands WB,

• A feed from Sandhouse WTW (groundwater fed) which will feed into the proposed Newton Leys development.

There is also an export of treated water into the Thames Water supply area (Aylesbury Vale) via Shenley WB and Mursley Water Reservoir (WR) in the west and southwest of the city.

East of M1 levels of off-site works will be more than for other growth areas since existing mains in that area do not have the capacity to serve such a major development.

As well as considering modelling of the water supply network, the Stage 2 WCS will also need to assess the capacity of the Water Treatment Works (WTW) feeding Milton Keynes.

7.7 Bedford and Milton Keynes Waterway

The Grand Union Canal (GUC) runs from Birmingham to River Thames at Brentford. It was built by James Barnes, a canal engineer between 1792 and 1805. The total distance of the canal is 220 km (137 miles). It includes several significant engineering achievements, the ascent of the Chilterns (highest point at Tring approx. 100 mAOD) and the aqueduct across the Upper Great Ouse using an ‘Iron Trunk’ set above the river. British Waterways are the statutory navigation authority for the GUC. A number of charitable trusts have been established along the canal to promote the wider recreational use of the waterway.

British Waterways, in collaboration with the Bedford and Milton Keynes Waterway Trusts, has plans to provide a new canal link between the GUC in Milton Keynes and the River Great Ouse in Bedford called the Bedford and Milton Keynes Waterway. The route of this new canal link was talked about as far back as early 2003, the total distance being 32 km (20 miles). Outline design is complete for the first 7km of the route, through Milton Keynes to just north of Junction 13 of M1.

The water resources aspects of this scheme were looked at by Halcrow (2004) for the section as far as M1 (J13). Their conclusion was that at least for this first stage (7km) that sufficient water resources are available from the existing abstraction points to meet the need of this canal extension. This assumes that

Final December 2008 75 Milton Keynes Council Water Cycle Study – Outline Strategy

no restrictions are placed on abstractions from the Upper Great Ouse between Stoke Bruerne in the north and Ivinghoe in the south (EA 2005 16 ). The EA and BW have an agreement that allows BW to maintain water levels with abstractions from the River Tove and Ouse near Stoke Bruerne. It must be noted however that the EA would not allow any additional licensed abstraction in summer from the River Tove and Ouse. Further investigation was planned for Stage 2 of this canal link beyond the M1 to Bedford. ‘ In 2007 detailed planning consent was granted for the section of the canal from the Eastern Expansion Area along the Broughton Brook and the remaining section to the GUC received outline planning consent. At the request of the EA and the IDB conditions were attached to both the detailed and outline consents to require further studies regarding water resources and flood risk before the development takes place . It is unclear whether this scheme will be of any practical benefit for the transfer of water resources. Stage 2 of MKWCS will need to consider this matter in more detail.

7.8 Water Resources and Water Supply Summary

• Milton Keynes is presently supplied by Wing and Grafham WTWs, which are in turn fed from Rutland Water and Grafham Water respectively,

• The forecast growth in demand for 57,950 new homes (by 2026) is estimated at 17 Ml/d for residential demand and a further 9 Ml/d for non-residential development. The latter demand is likely to be from commercial and service based industry. The combined total is approximately 26 Ml/d on average but could be as high as 29 Ml/d on average.

• In addition, the above estimates do not take into account of the Marston Vale Eco-Town, which could drawn up on an extra 6 Ml/d,

• AWS latest supply/demand balance indicates that the Milton Keynes and Newport Pagnell area currently only have sufficient DO to meet demand, not allowing for headroom, until 2019/20. Allowing for headroom, this shows there is already a resource shortfall. This position will be eased in the short term (by 2010) through developments at Wing WTW (supplied by Rutland Water),

• Beyond 2010, it may be necessary to supplement available resources by the development of local schemes, such as at Foxcote WTW, within the existing abstraction licence limits,

• In the longer term, a major regional resource development may be required, such as the River Trent Transfer Scheme. Further discussion of the resource scheme options are included in section 8.3.2.

16 EA 2005 – The Upper Ouse and Bedford Ouse CAMS

Final December 2008 76 Milton Keynes Council Water Cycle Study – Outline Strategy

• The mitigation measures being put in place at the Rutland Water SPA, such as the creation of wetland habitats, should enable full take-up of this licence quantity without any negative effects on the site,

• A number of other uncertainties – Climate Change, Review of Consents and Water Framework Directive remain and which may affect the water resources situation in the future and the status of available growth within Milton Keynes,

• Detailed configuration can be tested and hence costed using network models in the detailed WCS, although this will be dependent on the availability of information as to the location of development, demand and phasing.

Final December 2008 77 Milton Keynes Council Water Cycle Study – Outline Strategy

8 Water Cycle Option Development

8.1 Introduction

Chapters 5 to 7 assessed the existing constraints and existing baseline for the current WSI in Milton Keynes. This was undertaken in the context of analysing how much development could be brought forward with existing infrastructure or minimum investment in new infrastructure. This section discusses outline or strategic options for providing new infrastructure which has been identified as required to supply projected housing targets. This assessment needs to be undertaken before the development scenarios can be tested against the various water cycle assessment criteria.

8.2 Wastewater Option Development

8.2.1 Future Capacity and Upgrade Requirements

Wastewater Network

The initial high level assessment of the wastewater network has highlighted a number of areas with spare capacity to support growth in the short term (e.g. 5-10 years), with either no upgrades or minimal upgrades required (some areas are expected to be able to take all planned growth). However, the assessment has also highlighted areas where there is both an existing problem with capacity, or where there is likely to be issues with capacity (without significant infrastructure upgrades) post development. As an initial option, consideration should be given to the phasing of development, whereby development is ‘fast tracked’ in areas, where no (or minimal upgrades) are required. Further more detailed work (including network modelling) should be undertaken as part of the detailed (stage 2) WCS, to confirm the capacity issues highlighted in this outline study.

Treatment

AWS would be required to seek funding through the Price Review Process in order to provide any additional treatment required. AWS are currently examining the potential to increase treatment capacity at Cotton Valley WwTW.

AWS do not consider that the DWF consent will need to be revised until AMP6. Increased effluent discharges to the River Ouzel and River Great Ouse will impact on flood risk and water quality. Before approving increases in consented discharges to these rivers, the EA will require further catchment modelling to identify any necessary mitigation works particularly with reference to the

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lakes in Milton Keynes. This should either be included in the detailed stage of the water cycle study, the Level 2 SFRA or as an independent study for example a surface water management plan.

It is strongly recommended that as part of the detailed (stage 2) WCS, further information regarding the scheme to increase treatment capacity at Coton Valley should be obtained from AWS. This would then lead to a detailed review of process capacity and impacts on receiving watercourses and downstream sites. Such a review should also pay attention to upstream discharges on the River Great Ouse and River Ouzel, paying particular attention to regulatory standards and phosphorus since water quality impacts can be cumulative. Discharges should ideally be considered from headwaters to outfall using appropriate data and modelling software such as SIMCAT.

8.3 Water Resources Option Development

8.3.1 Introduction

At the present time, AWS are in the process of drawing together their new WRMP for AMP5 and beyond. An early indication of their likely strategy to be contained within their 2009 WRMP was presented in AWS’s Strategic Plan document for the next 25 years and which was published in December 2007. This document identified Milton Keynes as a demand hotspot, along with a number across its region (from Regional Spatial Strategy). A combination of water re-use (abstraction of water discharged upstream) and major WTW development at Clapham (near Bedford) were referred to. Along with these developments, there would be continued support to this area from the three major strategic reservoirs (and possibly supported by a Trent Transfer scheme in the longer term). In the draft WRMP09, latest document published by AWS in May 2008, it appears that there has been a shift towards a twin-track approach of demand management (leakage control and an enhanced metering programme) and use of more local solutions, where available, have been given greater emphasis over increased transfers. It is thought that the reason for this may be the requirement by OFWAT for carbon accounting to be taken into accounting all future WRMPs.

It is made clear in the 2009 draft WRMP that these plans have a number of uncertainties most notably:

• The Review of Consent is assumed to result in a loss of yield of only 5 Ml/d (although figures well in excess of this have been mentioned by the EA previously),

• A major Groundwater scheme in the Great Ouse catchment requires a licence to be granted by the EA. The latest information from AWS is that this scheme is not now likely to go ahead and that instead a combination of demand management measures and possibly a new major resource development may be required.

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• It is also assumed that no extra demand will come from neighbouring water companies (over and above the long-standing bulk transfers agreements),

• The Water Framework Directive has not been taken account of in the WRMP (see section 7.5.4).

8.3.2 Water Supply Strategy

Firstly, AWS is expected to maintain its levels of leakage at the close ELL (see section 7.5.2). Apart from metering, which is mentioned below, all other water efficiency measures will produce only small amounts of savings.

Short Term

In the short term, AWS will meet the growth in demand by a combination of enhanced metering (this will generate up to 10 Ml/d across the wider Ruthamford Zone WRZ-11 or pro-rata for the Milton Keynes/Newport Pagnell area, a saving of 1.3 Ml/d) and improvements to WTWs. The upgrading of Clapham WTW, planned for AMP5, would in turn release DO from Grafham to support growth in Milton Keynes. A further 10 Ml/d of DO is expected to come from these developments over the AMP5 period (2010-2015). The additional resource being made available from Wing is also key to meeting growth in Milton Keynes in both the short and medium term.

Medium Term

After 2015 (AMP6 and beyond), AWS propose to refurbish Foxcote WTW (source of supply - surface water intake and reservoir) local to Milton Keynes and which will provide approximately 7 Ml/d in the medium term. This source is already licensed to AWS, therefore the fact that the Upper Great Ouse is defined by the CAMS as having no water available should not impact on this scheme.

Long Term

In the longer term, AWS propose to make use of the extra discharges from Cotton Valley WwTW near Milton Keynes and to increase its abstractions downstream at Clapham WTW. This will be a phased development undertaken over the medium to longer term and which will hopefully yield a further 10 Ml/d from this site for the Bedford area, which will in turn release DO from Grafham. This extra yield at Clapham may require a variation to the licence (currently 27 Ml/d from surface water and 6 Ml/d from groundwater). Although the CAMS document states that the Bedford Great Ouse has no water available, it is the case that the slight increase in the licence quantity may be acceptable to the EA if it is part of a scheme to re-use water from further up the catchment.

In addition, a major regional resource development may be required in the long term, such as the River Trent Transfer Scheme. As part of this scheme, there may be a need to re-zone supplies from adjacent planning zones.

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The likely infrastructure requirements needed to supply this water is determined below with an indicative outline cost. The methodology used is similar to that used successfully on other WCS and which is outlined in the figure below. At this stage in the WCS process, it is noted that the costs are indicative only and should only be used as a way of determining the potential monetary impacts of providing the required water resource infrastructure for the predicted housing targets.

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Figure 8-1: Indicative costing process for broad scale water resource options Source: Scott Wilson

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In the case of Milton Keynes:

• AWS is expected to maintain its level of leakage at the ELL,

• The savings from the enhanced metering programme are expected to provide 1.3 Ml/d on average within this area (pro-rata from 10 Ml/d savings across the entire Ruthamford WRZ-11),

• The upgrading of Clapham WTW, which will in turn release DO from Grafham, to provide up to 10 Ml/d of yield,

• The refurbishment of Foxcote WTW to provide up to 7 Ml/d of yield,

• Further phased development at Clapham WTW involving abstraction of extra water discharged from Cotton Valley WwTW in Milton Keynes, this will again release DO from Grafham, to provide up to 10 Ml/d (subject to a licence variation).

• A transfer-in from Wing WTW, supplied from Rutland Water, would provide the remainder.

From these demand management measures and a range of water resource developments, it should be possible to provide sufficient resources to meet the forecast growth in demand of 26 Ml/d on average and potentially up to 29 Ml/d. These additional resources may not be sufficient to fully cover the 30% allowance for headroom which is recommended. Further support from the other major strategic reservoirs in the Ruthamford, along with any new resources development such as the Trent Transfer scheme may also be required to meet demand in Milton Keynes. This is particularly likely to be the case if the proposed development for an eco-town at Marston Vale is given the go ahead.

Referring to Figure 8-1 and by placing appropriate costs against the Resource Development, Production (Treatment) and Distribution, it is possible (using the calculations shown in the table at the bottom of this figure) to derive rough costs for water resources and water supply for this level of development. For example; it is estimated that in the short term approximately 10 Ml/d and in the long term 21 Ml/d (would come from existing licences (Grafham and Rutland) requiring only extra production capacity and more distant distribution costs (Model E). Whilst around a further 7 Ml/d would come from an existing surface water source at Foxcote (Model B). This also assumes that approximately 1 Ml/d from water savings (through an enhanced metering programme).

8.3.3 Anglian Water – Future Asset Management Planning

The following information has been provided by AWS, with regards to offsite requirements required to safeguard the water longer term water supply for Milton Keynes.

Significant offsite reinforcements are required to support the proposed growth in Milton Keynes and these include increased:

• WTW capacity,

• Storage,

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• Water mains reinforcements,

• Pumps upgrades.

A number of schemes have been identified by AWS to support the outstanding Local Plan growth (2001 - 2011 to deliver 24,100 new homes) the majority of this growth is located within the four key expansion areas:

• Western Expansion Area,

• Northern Expansion Area,

• Eastern Expansion Area,

• Central Milton Keynes.

To support growth in the short to medium term would require the following AMP4 (2005-2010) schemes, which are currently at detailed design or under construction. Schemes to be delivered as part of AMP4 include:

i. Wing WTW increased capacity,

ii. Wing Strategic Mains,

iii. Old Stratford pump upgrades.

Additional schemes to support growth in AMP5 (2010-2015) have also been identified however it is anticipated that this would not be sufficient to support the demand of the additional dwelling target to 2031. Future AMP5 (and beyond) schemes, which are to be driven by growth include:

iv. Reinforcement between Ampthill and Woburn Water Reservoirs,

v. Reinforcement between Old Stratford Pumping Station and Kiln Farm.

Assumed at this stage like for like reinforcement:

vi. Upgrade of Woburn Pumping Station,

vii. Increased storage, existing storage points identified in the strategy plans as requiring additional storage (Deanshanger, Woburn and Brickhill Copse Water Reservoirs,

viii. Resilience - Salcey to Deanshanger rail crossing - duplication of the existing main under the railway.

There are two major points of supply into Milton Keynes that transfer water into the east and west of the Milton Keynes grid main network. Water is transferred from the east via Woburn Sands water booster and Brickhill Copse Water Reservoir (predominately Grafham WTW) and from the west via Old Stratford Water Booster (predominately Wing WTW). The schemes identified above are to increase the strategic transfer capacity and storage however once additional information is

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available for the future large scale development areas the need for local offsite mains reinforcement can be reviewed.

Local offsite mains reinforcements have currently been identified to support the following growth areas:

• Western Expansion Area,

• Eastern Expansion Area,

• Newton Leys (supplied from Sandhouse WTW),

• Kingsmead and Tattenhoe.

The water cycle study indicates that up to 2011, allocations will be in accordance with the Local Plan. Over the period 2011-2026 there will be a focus of up to 8,500 houses in the urban area to support urban renaissance, which will be principally focused on Central Milton Keynes, Bletchley and Wolverton. As the existing mains in these areas will not have been designed for growth on such a large scale significant offsite mains reinforcements may be required.

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9 Generation of Flood Risk - SUDS Options

9.1 Introduction

Chapter 5 undertook an assessment of potential flood risks and hence constraints posed to potential development areas. This section considers flood risk generated as a result of development which is an important consideration with respect to the assessment of development scenarios and current national planning policy with regards to flood risk management.

In areas where development runoff is likely to be discharged to a river system, it is important that new development does not increase the risk of flood risk downstream (or indeed upstream) by increasing runoff rates to greater than that of the runoff generated by existing land use. In addition, it is important that new development does not increase the risk of overland flow to adjoining development areas by increasing the amount of impermeable area.

Milton Keynes has been developed around the concept of strategic and integrated surface water and flood risk management, with large flood storage reservoirs and engineered watercourse. The Drainage SPG states growth must provide strategic and integrated drainage systems. Therefore Strategic and Integrated drainage and SUDS is essential to continue the success of Milton Keynes.

9.1.1 National Flood Risk Policy - PPS25

PPS25 requires that all new development should ensure that runoff rates and runoff volumes from new development are not increased above that of the existing land use. Much of the ‘infill development within the Central Area will be on previously developed (brownfield) land; hence the requirement to reduce runoff rates as a result of rainfall will be less onerous for these developments, compared to those on Greenfield sites. For infill development on currently undeveloped land and development of the new areas, there will be a requirement to ensure that runoff rates and volumes are no greater than the Greenfield rates for the design event with return period of 1 in 100 years (with an allowance for climate change) and smaller rainfall events up to this level.

9.2 Flood Risk from Development – Strategic Options

9.2.1 Central Area

Unlike other urban and suburban areas, due to its nature Milton Keynes only has a brownfield regeneration target of 20%. Therefore the majority of new development within the Central Area (circa 80%) will be on Greenfield land and will significantly increase surface water runoff.

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Consideration should be given to on-site and strategic attenuation of surface water runoff generated from the Central Area, thus reducing the pressures on the existing surface water network.

9.2.2 Eastern Area

New development within the study area will primarily be constructed on Greenfield land. The amount of impermeable land is therefore likely to increase and it would be necessary to ensure SUDS techniques are employed in any development. The Development Framework for the Eastern Expansion Area sets out guidelines for surface water drainage from new development. Flood risk management and drainage infrastructure will be fully funded by the development. It considers SUDS, including wet and dry ponds, areas of open space, will retain and potentially enhance the linear park that runs through the site along Broughton Brook. The brief identifies five drainage catchment areas and the surface water from each will be intercepted by offline balancing ponds and wetlands and will attenuate peak discharge to between 1 and 5 l/s/ha for a storm of return period of 1 in 100 years, consideration will also need to be given to the effects of climate change.

The Broughton Gate and Nova Development Briefs (sites within the Eastern Expansion Area) also provide more site specific outlines for the individual sites for surface water drainage, but it is also important to consider strategic based SUDS in conjunction with site specific SUDS. Part of the Nova Development Brief explains that attenuated discharges will pass through piped systems and onto a wetland storage area adjacent to Broughton Brook. Discharges will be attenuated via site source control and flow attenuation measures. There will be a permanent wet meadow/swale feature and ancillary water balancing ponds on the southern edge of the floodplain. The development will extend the ‘Broughton Brook Linear Park’. Other potential SUDS techniques include underground tank storage, roof drainage storage and block-work paving (where appropriate). The drainage strategy for the Development Framework has included a 20% allowance for climate change.

9.2.3 Western Area

New development within the western study area will primarily be constructed on Greenfield land. The amount of impermeable land will therefore increase and it would be prudent to ensure SUDS techniques are employed in any development to minimise any potential increase in surface water runoff. The Development Framework for the Western Expansion Area gives an indication of potential surface water management techniques for the proposed development. Primarily this will be through a series of balancing ponds and open spaces. A balancing pond will be potentially located near the V4 at Watling Street. The aim of the surface water management plans will be to reduce peak discharge to 3l/s/ha for a 1 in 100 year storm event, consideration will also need to be given to the effects of climate change.

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Runoff will discharge to Loughton Brook and mitigation measures will be located along Loughton Brook. There will also be on-site ponds at the Kiln Farm site, following guidance from the IDB that storage would be more appropriate at this location than increased conveyance to Loughton Brook.

The development brief highlights that infiltration based SUDS are not likely to be appropriate in this area due to ground conditions and that balancing ponds should be able to deal with the entire volume of surface water runoff.

9.2.4 Northern Area

New development within the northern study area will primarily be constructed on Greenfield land. The amount of impermeable land is therefore likely to increase and it would be prudent to ensure SUDS techniques are employed in any development to minimise any potential increase in surface water runoff. It may be possible to attenuate surface water flows through utilising the numerous lagoons to the north of the development area. The Northern Expansion Area Development Framework has considered surface water management through the incorporation of SUDS into the development. Where ground conditions permit, this could include porous paving and soakaways.

9.2.5 South Western Area

Any development on Greenfield land will increase the amount of impermeable land and it would therefore be important to ensure SUDS techniques are employed in any development to minimise any potential increase in surface water runoff.

It is likely that the onus for surface water management of the site will fall to individual developers, through the implementation of integrated strategic management of surface water, drawing upon the resources of multiple developers as they look to promote an area for development. This approach is recommended by the EA and IDB, as it promotes sustainability and also avoids the construction of disparate systems.

9.2.6 Land East of the M1

Development on greenfield land (the majority of the study area) will increase the proportion of impermeable surfaces and it is therefore important to ensure that integrated SUDS techniques are employed in any development to minimise any potential increase in surface water runoff.

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In all development areas, development, flood risk infrastructure and mitigation measures must be sustainable in terms of future maintainability and whole life costs must be taken into consideration.

9.2.7 Rural Areas

Development on Greenfield land will increase the proportion of impermeable surfaces and it would therefore be important to ensure SUDS techniques are employed in any development to minimise any potential increase in surface water runoff.

In all development areas, developments and, flood risk infrastructure and mitigation measures must be sustainable in terms of future maintainability and whole life costs must be taken into consideration.

9.3 SUDS Utilisation

In order to reduce runoff rates from developed sites to that of existing (and where possible to achieve ‘betterment’), PPS25 and its companion guidance recommend that Sustainable Drainage Systems (or techniques) known collectively as SUDS are used.

Surface water drainage from any new development within Milton Keynes should be designed in accordance with recommendations as set out PPS25 and the SUDS Manual (CIRIA C697) as a minimum and also in consultation with the EA and IDB (where appropriate). Consideration should also be given to including porous paving (where permissible) and water recycling techniques such as rainwater harvesting and greywater recycling.

In general, there are advantages to be gained to developing drainage strategies for site wide developments such that strategic scale options such as utilising the existing attenuation lakes can be developed at lower overall cost (albeit with potential new linkages), but also to:

• Maximise green infrastructure linkage,

• Maximise ecological enhancement,

• Maximise water quality benefits from retention and filter type SUDS,

• Contribute towards the point system for Code for Sustainable Homes grading.

Considering the options now, is a key consideration for this strategic WCS. The following sections outline some of the key outline or strategic considerations for SUDS for the development areas, and it is recommended that the Stage 2 study develops site wide strategic drainage plans for the development scenarios and areas taken forward into the next planning stage. Property based SUDS should be provided in addition to strategic SUDS, and not instead of.

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9.3.1 Surface Water Attenuation

Once more is known about the precise numbers of housing and likely layouts of the sites, it is recommended that the detailed requirement for different types of SUDS is undertaken (possibly in the Stage 2 WCS and certainly at site specific FRA stage). At this stage it can be assumed that a percentage of the development areas can be set aside as green space and notwithstanding other SUDS techniques. Therefore the remaining runoff generated from rainfall events will have to be attenuated or stored in surface water systems such as large scale strategic balancing lakes, or smaller site-specific ponds.

Once draft masterplans for each of the developments are available, then further work will be required to determine the increase in run off due to development, allowing the required attenuation volumes to be calculated. Guidance in the Preliminary Rainfall Runoff Management for Developments or the Interim Code of Practice for SUDS should be referred to.

Once post development run off rates and volumes have been determined (following masterplanning), surface water attenuation will need to be provided, utilising SUDS. Infiltration based SUDS are limited within Milton Keynes due to the nature of the underlying geology and presence of SPZs (to the South East), primary consideration should be given to the use strategically located large-scale attenuation facilities, developed to attenuate water from a number of developments (rather than a number of individual disparate ponds, per development). In some instance, there may be a need to consider the use of smaller scale site-specific features such as rainwater harvesting, filter strips, swales and smaller balancing ponds.

9.3.2 SUDS options

A description of the type of SUDS that could be considered for the Milton Keynes study areas are dependent on the type of housing and density that is envisaged is included in Appendix E – SUDS Options Details.

The SUDS Hierarchy

The EA and DEFRA currently suggest that the SUDS hierarchy is adopted when considering SUDS techniques to be adopted for new development. This lists the order in which different SUDS techniques should be considered for a site in terms of their considered sustainability. SUDS techniques at the top of the hierarchy are preferable for their potential ecological and water quality benefits.

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Most Sustainable Pollution Landscape and SUDS technique Flood Reduction Reduction Wildlife Benefit

Living roofs

Basins and ponds - Constructed wetlands -Balancing ponds -Detention basins -Retention ponds

Filter strips and swales

Infiltration devices -soakaways -infiltration trenches and basins Permeable surfaces and filter drains -gravelled areas -solid paving blocks -porous paviors

Tanked systems -oversized pipes/tanks Least -storms cells Sustainable

Figure 9-1: SUDS Hierarchy Source: SUDS - A Practical Guide, Environment Agency Thames Region

9.3.3 Infiltration SUDS

Infiltration is a key factor in reducing runoff rates and volumes, as it reduces the reliance on surface or engineered storage systems such as balancing ponds or storage tanks. Figure 9-1 places some surface storage features near to the top of the hierarchy list on the basis of habitat creation and water quality benefits. The benefits of such systems is considered in Section 9.3.4; however, encouraging natural infiltration by creation of open grassland landscaping (where contamination is not an issue) should be encouraged first for large developments to maximise natural runoff rate reduction and to encourage natural recharge of groundwater systems.

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Maximisation of green infrastructure and open space is recommended for large new development areas where the soil and geology is sufficiently permeable to make it a feasible option. Infiltration can also be encouraged via managed SUDS techniques such as soakaways, swales or infiltration trenches.

Infiltration based SUDS would be subject to site-specific ground investigation works by the developer.

Limitations

Given that much of the study area is underlain by impermeable geology either Boulder Clay or Oxford Clay (which lies below the Boulder Clay), infiltration is not a key consideration for new development in Milton Keynes. Indeed the majority of surface water generated from Milton Keynes is attenuated by a series of purpose built attenuation lakes.

Further to the south lies the Woburn Sands, which is generally more permeable than the clayey strata - the draft Level 1 SFRA states that the IDB have expressed concerns that increased development and use of infiltration based SUDS in the area could lead to localised groundwater flooding.

The issue of groundwater flooding could also occur along the northern boundary of Milton Keynes and where the River Great Ouse flows through part of northern development area. The river through this section is running across the Great Oolite sequence, a Major Aquifer and which will probably contribute to flow to river for at least part of the year. A line running west-southwest to east-northeast and dissecting the Northern development area represents the boundary between the Great Oolite sequence and clayey strata to the south of this line.

Groundwater Quality - Vulnerability

Groundwater resources are vulnerable to contamination from both direct sources (e.g. into groundwater) or indirect sources (e.g. infiltration of discharges onto land which in turn may feed down to the groundwater). Groundwater vulnerability within the study area has been determined by the EA, based on a review of aquifer characteristics, local geology and the leaching potential of soils. The vulnerability of the groundwater is important when advising on the suitability of SUDS.

According to the EA’s large scale groundwater vulnerability map (1:100,000), the main part of Milton Keynes is defined as Non-Aquifer (this area being coincident with Oxford Clay outcrop). The Great Oolite outcrop to the north is defined as a Major Aquifer with Intermediate vulnerability. As already mentioned, the Great Oolite outcrop area encroaches onto the edge of the broadly defined Northern study area. The Lower Greensand to the south is also a Major Aquifer and in the High vulnerability classification. However this area does not to encroach onto either the South Western or Eastern study areas.

Source Protection Zones

The Environment Agency defines groundwater SPZs around all major groundwater abstraction points. SPZs are defined to protect areas of groundwater that are used for potable water supply,

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including both public and private supplies (including mineral and bottled water), or where the water is used in the production of commercial food and drinks.

SPZs are defined based on the time it takes for pollutants to reach an abstraction point from any point at the water table. It does not include the time taken for water to infiltrate from the surface down to the water table. This transmission time enables the EA to define 3 zones around a groundwater abstraction point.

Zone 1 (Inner Protection Zone) – This is defined as ‘any pollution that can travel to the borehole within 50 days from any point within the zone is classified as being inside zone 1’,

Zone 2 (Outer Protection Zone) – This is defined as the area that ‘covers pollution that takes up to 400 days to travel to the borehole, or 25% of the total catchment area – whichever area is the biggest’,

Zone 3 (Total Catchment) - The total catchment is the total area needed to support removal of water from the borehole, and to support any discharge from the borehole,

Depending on the nature of the proposed development and the location of the development site with regards to the SPZs, restrictions may be placed on the types of SUDS appropriate to certain areas. Infiltration into SPZ1 is generally only permitted for clean roof runoff. Runoff from roads and car parks is not acceptable in SPZ1 and is only acceptable in SPZ2 if there are sufficient controls in sources of contamination (e.g. oil separators) and that there is sufficient depth between the unsaturated soil into which the water is drained and the saturated water table in the geology below.

The SPZ designations for Milton Keynes and surrounds are shown in Figure 9-2.

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SPZ Zones

Zone 1 – Inner Protection Zone Zone 2 – Outer Pr otection Zone Zone 3 – Total Catchment

Figure 9-2: Milton Keynes Source Protection Zones Source: EA Website

Figure 9-2 shows that there are two Zone 1 SPZs (coloured red) to the southeast of Milton Keynes. These zones are all within the outcrop of Woburn Sands (Lower Greensand (LGS)) of the Cretaceous Period). The shape of groundwater catchment zone for the more southerly of these sources implies a northwest-southeast groundwater flow direction. Although in the case of the more northerly source (around Aspley Guise), the groundwater flow direction is more northerly. The close proximity of this source to the edge of LGS outcrop apparently causes the Zone 3 – total catchment area for this source to extend out in both westerly and easterly direction, which would indicate that the hydraulic gradients in this area are quite gentle. There are no further SPZs shown on the EA website relating to Milton Keynes and the surrounding areas.

Central Area

There are no groundwater source protection zones adjacent to the Central Area.

Eastern Area

See comments below on South Western Area.

Western Area

There are no groundwater source protection zones adjacent to the Western Area.

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Northern Area

There are no groundwater source protection zones adjacent to the Northern Area.

South Western Area

The SPZs to the southeast of Milton Keynes all occur on the outcrop of Woburn Sands (Lower Greensand – LGS). The catchment areas of these sources do not extend beyond the outcrop of LGS and therefore they will not extend into the nearest development sites to these sources e.g. South Western and Eastern Areas.

Although it is not clear on what the precise direction of groundwater flow is beneath Milton Keynes within the clayey strata, any movement which does take place within these layers is likely to do so at a very slow rate. This fact combined with the relative distance of the South-Western and Eastern study areas from these SPZs will mean that activities within these areas are unlikely to represent a threat to these sources.

It should be noted that below the clayey strata beneath Milton Keynes lie the Kellaway Beds in which the regional groundwater flow has been assessed to be in a direction from southwest to northeast. This means that any pollution present at depth beneath Milton Keynes is most likely to be not in the direction of the sources situated southeast of Milton Keynes, and instead towards the northeast along the line of the River Great Ouse.

Land East of M1

There are no SPZs adjacent to the land east of the M1.

Rural Areas

There are no SPZs adjacent to the Rural Areas.

9.3.4 Link to Green Infrastructure

Green Infrastructure is a network of protected sites, nature reserves and green spaces that occur at all scales from the urban centre to the rural countryside. The aim of the Milton Keynes Green Infrastructure Plan is to identify environmentally sensitive areas and provide a long term plan for enhancing their ecosystems, recreational and cultural significance. One of the specific objectives is to undertake a sensitivity analysis for the development sites to identify green infrastructure links from and to the rural and urban areas.

The report notes the importance of the river or ‘green’ corridors as natural ecological systems. The opportunities in the area have been identified as enhancing the links to and along the Rivers Great Ouse, and Ouzel and smaller watercourses such as Broughton Brook; and the incorporation of small scale SUDS and the possibility of strategic SUDS adjacent to the rivers, as has also been highlighted in the Expansion Area development frameworks. The creation of linkage with green infrastructure

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vision is perhaps greatest for the larger Eastern and Western Areas as there is potential for strategic scale SUDS such as balancing lakes to link with the corridor of the River Great Ouse and the River Ouzel. This is particularly pertinent given that infiltration is likely to be significantly constrained in many of the development sites due to unsuitable underlying geology.

9.4 Flood Risk Management Summary

In summary, the following key flood risk management points can be made regarding the site.

• Many areas, but more specifically the Central and the South Western and Western Areas, are likely to be significantly limited in terms of opportunities for utilisation of infiltration SUDS due to unsuitable underlying geology,

• Potential contamination of the SPZs within the Eastern and South Western Areas is a risk with development activities associated with these areas,

• The Eastern Area and Western Area provide the best opportunities for linking with green infrastructure opportunities in the town via linking surface water attenuation features such as swales and balancing ponds to existing green corridors and the proposed Bedford –Milton Keynes waterway link,

• Significant preliminary works (in the form of Development Frameworks) have already been undertaken. These partially determine the scope and potential for surface water management in the main development areas. . Some of these development areas may contain more than one sub-catchment and it would then be appropriate to agree different rates of discharge to the individual watercourses on site. At this stage it may be more relevant to refer to the guidance in the Preliminary Rainfall Runoff Management for Developments or the Interim Code of Practice for SUDS These Development Frameworks should be developed further and implemented in conjunction with the key stakeholders including the EA during the Stage 2 WCS. They should also be used as models, for the areas where no Development Framework currently exists.

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10 Ecological Assessment

10.1 Objectives and Approach

The initial Stages (screening stages) of a Habitats Regulations Assessment have been undertaken for the first stage of the Outline Stage 1 WCS. Until the development areas and development scenarios are agreed in detail following review of all planning considerations, it is not possible to complete a full assessment on the WCS. This will be a requirement of the Stage 2 Detailed strategy, but a screening study for the Appropriate Assessment is suitable for a Stage 1 WCS in order to identify if they are any ecological constraints to the outline study.

As well as the European Sites potentially affected, the screening study has considered other nationally, regionally and local designated sites such that a comprehensive assessment of ecological impacts of the WCS is considered.

10.1.1 Scope of Assessment

The nearest European site 17 to any of the Milton Keynes growth areas is the Chiltern Beechwoods Special Area of Conservation (SAC) (Ashridge Commons & Woods SSSI) situated approximately 25km to the southeast. This site is not particularly hydrologically sensitive and is considerably outside any possible zone of influence from water abstraction or discharge associated with Milton Keynes. The nearest statutory sites 18 to any of the growth areas are shown in Table 10-1.

17 European sites : Widely used term for those internationally important wildlife sites designated in order to comply with the obligations of the EC Birds Directive (1979) and EC Habitats Directive (1992) 18 Statutory site : Wildlife sites designated under national legislation, specifically the National Parks & Access to the Countryside Act 1949 and Wildlife & Countryside Act 1981 (as amended). These are Sites of Special Scientific Interest (SSSI), National Nature Reserves (NNR) and Local Nature Reserves (LNR)

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Table 10-1: Statutory Sites Adjacent to Milton Keynes Location in Site terms of study Character Hydrological sensitivity areas 19 There are ponds within this site but it is Howe Park Within the uncertain at this stage as to whether they Wood southern corner of Dry woodlands are hydrologically connected to SSSI the Western Area watercourses or aquifers Within the Oxley Highly hydrologically sensitive, linked to southern corner of Flood meadows Mead SSSI the Shenley Brook the Western Area A series of ancient woodlands There are ponds within this site but it is To the south east Marston and small ponds coupled with uncertain at this stage as to whether they of the Land East Thrift SSSI drier habitats such as are hydrologically connected to of M1 grassland watercourses or aquifers A series of wetlands and small Hydrologically sensitive, linked to the Blue Within the South ponds coupled with drier Water Eaton Brook, a tributary of the River Lagoon Western Area habitats such as grassland and Ouzel that in turn flows into the Great LNR woodland Ouse Kings Wood National Nature Reserve lies just outside the south eastern boundary of Milton Keynes Unitary Authority, but this is more than 3km from the eastern boundary of the nearest study area (South Western Area).

The potential water sources for development were outlined in Section 7. It is reasonable to conclude that any increased volumes of treated sewage effluent generated by the growth areas will be discharged to these same watercourses, principally via the Cotton Valley WwTW.

The greatest ecological water quality issue associated with the new growth areas is the increase in the loading of phosphorus that might be expected to result from an increased volume of treated effluent being discharged to surface watercourses. For the recent years (2003 to 2006) the Rivers Great Ouse and Ouzel generally achieved the RQO Grade 3 (‘Moderate Ecological Status’) in all cases. The most prominent feature of the summary data was the consistently high nutrient grades for Nitrogen (N) and Phosphorous (P). In the River Great Ouse, the Grades between 2003 and 2006 were always ‘very high’ for phosphate, and ‘high’ for nitrate. The sources of phosphorus to water are many and varied, but can be conveniently ascribed to agricultural (grass and arable) and non- agricultural (large WwTW, trade discharges, smaller WwTW and domestic systems). Much investment has been undertaken to improve discharges from major point sources such as larger WwTWs (>10,000 population equivalent [PE]) and there is increasing attention given to diffuse sources.

The possible impacts that require consideration in this report are therefore:

• Reduction in flow rates and volumes, to such a degree that damage is caused to designated sites,

19 Although there may be other impacts on these sites associated with placing growth in these areas, only hydrological impacts are considered in this report given that it is focussed on the Water Cycle Strategy

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• Increased phosphorus load (and potentially concentration) in downstream sites, coupled with an increase in total oxidized nitrogen, potential lowering of dissolved oxygen and an increase in biological oxygen demand (although EA comments are that increased phosphorus load impacts will be negligible due to already high existing levels),

• Potential increase in water velocity and levels in downstream sites, notable at low/normal flows, as a result of the additional wastewater volumes entering the river,

• Drawdown of water within Water Eaton Brook due to possible abstraction from the River Ouzel, leading to adverse effects on the Blue Lagoon LNR.

10.1.2 Methodology

The need for Appropriate Assessment is set out within Article 6 of the EC Habitats Directive 1992, and interpreted into British law by Regulation 48 of the Conservation (Natural Habitats & c) Regulations 1994 (Box 1). The ultimate aim of appropriate assessment is to “maintain or restore, at favourable conservation status, natural habitats and species of wild fauna and flora of Community interest” (Habitats Directive, Article 2(2)). This aim relates to habitats and species, not the European sites themselves, although the sites have a significant role in delivering favourable conservation status.

Box 10-1: The legislative basis for “Appropriate Assessment”

Habitats Directive 1992

Article 6 (3) states that:

“Any plan or project not directly connected with or necessary to the management of the site but likely to have a significant effect thereon, either individually or in combination with other plans or projects, shall be subject to appropriate assessment of its implications for the site in view of the site's conservation objectives.”

Conservation (Natural Habitats &c. Regulations) 1994

Regulation 48 states that:

“A competent authority, before deciding to … give any consent for a plan or project which is likely to have a significant effect on a European site … shall make an appropriate assessment of the implications for the site in view of that sites conservation objectives ”.

“… The authority shall agree to the plan or project only after having ascertained that it will not adversely affect the integrity of the European site ”.

In the past, the term “Appropriate Assessment” has been used to describe both the overall process and a particular stage of that process (see below). Within recent months, the term Habitat Regulations Assessment has come into use in order to refer to the process that leads to an

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“Appropriate Assessment”, thus avoiding confusion. Throughout this report, Habitat Regulations Assessment is used to refer to the overall procedure required by Regulation 48 of the Conservation (Natural Habitats &c.) Regulations 1994 (as amended 2007).

In practice, Habitats Regulations Assessment of projects can be broken down into three discrete stages, each of which effectively culminates in a test. The stages are sequential, and it is only necessary to progress to the following stage if a test is failed. The stages are:

Stage 1 – Likely Significant Effect Test

This is essentially a risk assessment, typically utilising existing data, records and specialist knowledge. The purpose of the test is to decide whether ‘full’ Appropriate Assessment is required. The essential question is:

”Is the project, either alone or in combination with other relevant projects and plans, likely to result in a significant adverse effect upon European sites?”

If it can be demonstrated that significant effects are unlikely, no further assessment is required.

Stage 2 – Appropriate Assessment

If it cannot be satisfactorily demonstrated that significant effects are unlikely, a full “Appropriate Assessment” will be required. In many ways this is analogous to an Ecological Impact Assessment, but is focussed entirely upon the designated interest features of the European sites in question. Bespoke survey work and original modelling and data collation are usually required. The essential question here is:

“Will the project, either alone or in combination with other relevant projects and plans, actually result in a significant adverse effect upon European sites, without mitigation?”

If it is concluded that significant adverse effects will occur, measures will be required to either avoid the impact in the first place, or to mitigate the ecological effect to such an extent that it is no longer significant. Note that, unlike standard Ecological Impact Assessment, compensation for significant adverse effects (i.e. creation of alternative habitat) is not permitted at the Appropriate Assessment stage.

Stage 3 – Imperative Reasons of Overriding Public Interest (IROPI) Test

If a project will have a significant adverse effect upon a European site, and this effect cannot be either avoided or mitigated, the project cannot proceed unless it passes the IROPI test. In order to pass the test it must be objectively concluded that no alternative solutions exist. The project must be referred to Secretary of State on the grounds that there are Imperative Reasons of Overriding Public Interest as to why the plan should nonetheless proceed. The case will ultimately be decided by the European Commission.

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This report deals with the first stage of Habitat Regulations Assessment – the Likely Significant Effect Test.

10.2 Sites within Milton Keynes Unitary Authority

There are no European sites within or local to Milton Keynes Unitary Authority.

10.3 Sites of Special Scientific Interest 10.3.1 Howe Park Wood SSSI (SP832343)

This site is ancient woodland with ponds. Although the woodland is not particularly hydrologically sensitive, the ponds clearly are sensitive and it is uncertain at this stage as to whether they are hydraulically linked with any aquifers or watercourses from which abstraction would be likely to take place. This should be investigated at the next stage.

10.3.2 Oxley Mead SSSI (SP818348)

This flood meadow site is highly hydrologically sensitive and is hydraulically linked to the Shenley Brook. It is not known at this screening stage as to whether the brook is hydraulically linked with any aquifers or watercourses from which abstraction would be likely to take place. This should be investigated at the next stage.

10.3.3 Marston Thrift SSSI (SP973417)

This SSSI is predominantly an ancient ash/maple woodland which also supports damp grassland communities, including pendulous sedge ( Carex pendula ) and rushes ( Juncus spp ). There are also woodland streams and ponds. Although the woodland is not particularly hydrologically sensitive, the ponds clearly are sensitive and it is uncertain at this stage as to whether they are hydraulically linked with any aquifers or watercourses from which abstraction would be likely to take place. This should be investigated at the next stage.

10.4 Local Nature Reserves 10.4.1 Blue Lagoon LNR

The Blue Lagoon Local Nature Reserve lies on the site of a former brickworks. Two pits were excavated here. The northern Water Eaton pit was flooded in the 1940's when the Water Eaton Brook broke its banks. The brickworks were demolished in 1970 and the southern Flettons pit was used for landfill in the early 1980's. This area has now been landscaped into an attractive string of ponds and hills planted with woodland. Around the Blue Lagoon natural colonisation of the spoil heaps has formed grassland and scrub woodland. The grassland is especially rich in plants and

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animals including some typical of chalk downland but very rare in North Buckinghamshire. The re- landscaped Flettons pit with its small ponds has greatly increased the amount of shallow water habitat. Between the ponds and plantations areas were left unseeded for wild plants to colonise.

10.4.2 Screening Opinion

All of the sites identified above are likely to be hydrologically sensitive to varying degrees, and it will be necessary as part of the next stage to determine whether there is any hydraulic connection between the Shenley Brook or the ponds within Howe Park Wood SSSI and any watercourses or aquifers that will be used for abstraction for the public water supply. Until that time, it is not possible to screen out adverse effects of the water cycle strategy on these two sites.

The Blue Lagoon Local Nature Reserve is hydrologically connected to the River Ouzel through the Water Eaton Brook and it will therefore be necessary to determine as part of the next stage whether any possible abstraction from this River might lead to drawdown of water levels within Water Eaton Brook, leading to adverse effects on the Blue Lagoon LNR.

It is therefore not possible at this stage to screen out adverse effects on any of these three local sites.

10.5 Downstream Sites 20 - Special Areas of Conservation 10.5.1 Portholme SAC

This area lies within Huntingdonshire and holds grassland communities of the alluvial flood meadow type. It is the largest surviving traditionally-managed meadow in the UK, with an area of 104 ha of alluvial flood meadow (7% of the total UK resource) and the site is designated as an SAC for this resource. Watercourses on the periphery of the site have populations of some uncommon invertebrates, including one dragonfly, which is of a nationally restricted distribution. The meadow is surrounded by channels of the River Ouse, and the Alconbury Brook is close by. In winter and early spring Portholme is inundated by floodwaters. This provides natural fertilising of the soil and it is this seasonal flooding coupled with the traditional management that maintains the diversity of the natural plant communities.

10.5.2 Ouse Washes SAC

The Ouse Washes are located in eastern England on one of the major tributary rivers of The Wash. It is an extensive area of seasonally flooding wet grassland ('washland') lying between the Old and New Bedford Rivers (which are hydraulically connected to the River Great Ouse) and acts as a floodwater storage system during winter months. The cycle of winter storage of floodwaters from the river and traditional summer grazing by cattle, as well as hay production, have given rise to a mosaic of rough grassland and wet pasture, with a diverse and rich ditch fauna and flora. The Ouse Washes

20 Only sites understood to be hydrologically linked to the River Great Ouse and situated downstream of Milton Keynes are included

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were designated as an SAC for their population of spined loach. This fish is thought to be largely confined to oxygen rich waters where the substratum consists of fine, organic rich sediment.

10.5.3 The Wash and North Norfolk Coast SAC

The Wash is located on the east coast of England and is the largest estuarine system in the UK. It is fed by the rivers Witham, Welland, Nene and Great Ouse that drain much of the east Midlands of England. The Wash comprises very extensive saltmarshes, major intertidal banks of sand and mud, shallow waters and deep channels.

The eastern end of the site includes low chalk cliffs at Hunstanton. In addition, on the eastern side, the gravel pits at Snettisham are an important high-tide roost for waders. The intertidal flats have a rich invertebrate fauna and colonising beds of Glasswort Salicornia spp. which are important food sources for the large numbers of waterbirds dependent on the site. The sheltered nature of The Wash creates suitable breeding conditions for shellfish, principally Mussel Mytilus edulis , Cockle Cardium edule and shrimps. These are important food sources for some waterbirds such as Oystercatchers Haematopus ostralegus . The Wash is designated as a Special Area of Conservation for supporting the following features of European importance:

• Subtidal sandbanks,

• Intertidal mudflats and sandflats,

• Shallow inlets and bays,

• Reefs,

• Mediterranean saltmarsh scrub,

• Lagoons,

• Common seal,

• Otter.

10.5.4 Screening Opinion

There are two significant rivers (the Ivel and the Kym) that drain into the River Great Ouse between Milton Keynes and Portholme SAC. Given that any abstraction from the River Great Ouse at Milton Keynes is likely to be matched by an increased scale of effluent discharge into the same river and that additional water volume is added to the Great Ouse by the watercourses identified above, it is considered unlikely that significant flow reductions in the Great Ouse at Portholme SAC would be likely as a result of any of the new growth at Milton Keynes, even in combination with other developments that will abstract water from the Ouse upstream of Huntingdonshire.

Reduced flows are more likely to have an adverse effect on The Wash; siltation resulting from low flows is already recognised as a problem. Given that additional abstraction from the Great Ouse at

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Milton Keynes is likely to be matched by an increased scale of effluent discharge into the same River and that additional water volume is added to the Great Ouse by the watercourses identified above, it is considered unlikely that increased abstraction at Milton Keynes will lead to significant reduction of freshwater entering The Wash SAC.

Increased flows can lead to prolonged flooding of the Ouse Washes SAC and the spined loach (for which the SAC was designated due to their rarity in Europe, though they are quite common here) is associated with slow flowing watercourses, such that a significant increase in flow rates may render the Ouse unsuitable for the species. However, advice from the EA is that Spined Loach is a hardy species and that they should not be affected by any increased flow. However, given that the discharge of treated sewage effluent to the Great Ouse from Milton Keynes is likely to be matched by an increase in abstraction from the same watercourse significant increases in flow are unlikely to occur as a result of any of the expansion areas at Milton Keynes.

The Environment Agency’s Review of Consents has concluded that, although the concentrations of phosphorus in the rivers adjacent to The Ouse Washes are considered to be too high, action at other WwTWs within the Great Ouse catchment will allow the target quality to be met. Funding for the necessary improvements has been made available in AMP4, and all schemes are to be completed by the end of 2009. However, there is nonetheless potential for future development to exceed these standards and require further review of other sources of phosphorus.

There is potential for dilution of any phosphates contained in treated sewage effluent discharged to the Great Ouse from Milton Keynes due to the four identified tributaries of the Great Ouse upstream of Portholme SAC, The Ouse Washes SAC or The Wash SAC. However, it is reasonable to conclude that some of these watercourses may themselves carry large loads of phosphate due to increased development within the South East and East of England, and diffuse sources. Therefore, on a cumulative basis, a possible impact on these European sites cannot be discounted (even though Milton Keynes individual contribution may well be small). It is understood that the main Milton Keynes WwTW (Cotton Valley WwTW) is already at the limits of Best Available Technology with regard to phosphate stripping and it may therefore be necessary to review all sources of phosphorus within the River Ouse catchment in order to maintain the target river concentration at the Ouse Washes/Portholme Meadow sites.

At this stage it is therefore not possible to screen out adverse cumulative water quality effects on these three Special Areas of Conservation. This issue will therefore require further exploration at the next stage.

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10.6 Downstream Sites - Special Protection Areas 10.6.1 Ouse Washes SPA

The washlands support both breeding and wintering waterbirds. In summer, there are important breeding numbers of several wader species, as well as spotted crake Porzana porzana . In winter, the site holds very large numbers of swans, ducks and waders. During severe winter weather elsewhere, the Ouse Washes can attract waterbirds from other areas due to its relatively mild climate (compared with continental Europe) and abundant food resources. In winter, some wildfowl, especially swans, feed on agricultural land surrounding the SPA. The site was designated as an SPA for regularly supporting 64,392 waterfowl, including populations of European importance of the following migratory species:

• Ruff,

• Spotted Crake,

• Bewick's Swan,

• Hen Harrier,

• Whooper Swan,

• Black-tailed Godwit,

• Gadwall,

• Shoveler,

• Pintail,

• Pochard,

• Wigeon.

10.6.2 The Wash SPA

The Wash is of outstanding importance for a large number of geese, ducks and waders, both in spring and autumn migration periods, as well as through the winter. The SPA is especially notable for supporting a very large proportion (over half) of the total population of Canada/Greenland breeding knot Calidris canutus islandica . In summer, the Wash is an important breeding area for terns and as a feeding area for marsh harrier Circus aeruginosus that breed just outside the SPA. The Wash was designated as a Special Protection Area for supporting a bird assemblage of international importance by regularly supporting 400,273 waterfowl and for supporting populations of European importance of the following migratory species:

• Common Tern,

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• Little Tern,

• Marsh Harrier,

• Avocet,

• Bar-tailed Godwit,

• Golden Plover,

• Whooper Swan,

• Ringed Plover,

• Sanderling,

• Black-tailed Godwit,

• Curlew,

• Dark-bellied Brent Goose,

• Dunlin,

• Grey Plover,

• Knot,

• Oystercatcher,

• Pink-footed Goose,

• Pintail,

• Redshank,

• Shelduck,

• Turnstone.

10.7 Ramsar Sites 10.7.1 The Wash Ramsar Site

The Wash is designated as a Ramsar site for the following reasons:

• The Wash is a large shallow bay comprising very extensive saltmarshes, major intertidal banks of sand and mud, shallow water and deep channels,

• The site qualifies because of the inter-relationship between its various components including saltmarshes, intertidal sand and mud flats and the estuarine waters. The saltmarshes and the plankton in the estuarine water provide a primary source of organic material, which, together

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with other organic matter, forms the basis for the high productivity of the estuary. Internationally important wintering waterfowl assemblage,

• The site supports a wintering waterbird assemblage of international importance.

Species occurring at numbers of international importance are:

• Oystercatcher,

• Grey plover,

• Red knot,

• Sanderling,

• Curlew,

• Common redshank,

• Ruddy turnstone,

• Pink-footed goose,

• Dark-bellied brent goose,

• Common shelduck,

• Northern pintail,

• Dunlin,

• Bar-tailed godwit,

• Ringed plover,

• Black-tailed godwit,

• Golden plover,

• Northern lapwing.

10.7.2 Ouse Washes Ramsar Site

The Ouse Washes is designated as a Ramsar site for the following reasons: • The site is one of the most extensive areas of seasonally-flooding washland of its type in Britain,

• The site supports several nationally scarce plants, including small water pepper Polygonum minus , whorled water-milfoil Myriophyllum verticillatum , greater water parsnip Sium latifolium , river waterdropwort Oenanthe fluviatilis , fringed water-lily Nymphoides peltata , long-stalked pondweed Potamogeton praelongus , hair-like pondweed Potamogeton trichoides , grass-wrack

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pondweed Potamogeton compressus , tasteless water-pepper Polygonum mite and marsh dock Rumex palustris ,

• Invertebrate records indicate that the site holds relict fenland fauna, including the British Red Data Book species large darter dragonfly Libellula fulva and the rifle beetle Oulimnius major,

• The site also supports a diverse assemblage of nationally rare breeding waterfowl associated with seasonally-flooding wet grassland,

• The site supports a wintering waterbird assemblage of international importance.

Species occurring at levels of international importance are:

• Tundra swan,

• Whooper swan,

• Eurasian wigeon,

• Gadwall,

• Eurasian teal,

• Northern pintail,

• Northern shoveler,

• Mute swan,

• Common pochard,

• Black-tailed godwit.

10.8 Sites of Special Scientific Interest 10.8.1 Felmersham Gravel Pits SSSI and Stevington Marsh SSSI

These sites lie approximately 5km east of Milton Keynes and are hydrologically linked to the River Great Ouse. Therefore excessive abstraction from the Great Ouse during periods of low flow could potentially lead to drawdown of water within both sites. In addition, increased discharge of treated sewage effluent could lead to increased phosphate levels and deterioration in water quality.

10.8.2 The Wash SSSI

The whole area is of exceptional biological interest. The intertidal mudflats and saltmarshes represent one of Britain's most important winter feeding areas for waders and wildfowl outside of the breeding season. Large numbers of migrant birds, of international significance, are dependant on the rich supply of invertebrate food. The saltmarsh and shingle communities are of considerable botanical

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interest and the mature saltmarsh is a valuable bird breeding zone. In addition the Wash is also very important as a breeding ground for Common Seals.

10.8.3 Ouse Washes SSSI

The site is one of the country’s few remaining areas of extensive washland habitat. It is of particular note for the large numbers of wildfowl and waders that it supports, for the large area of unimproved neutral grassland communities that it holds and for the richness of the aquatic fauna and flora within the associated watercourse. The grassland communities of the area are characterised by such grasses as reed and floating sweet-grass Glyceria maxima and G.fluitans , reed canary-grass Phalaris arundinacea , marsh foxtail Alopecurus geniculatus together with a variety of sedges and rushes. Typical herbs include amphibious bistort Polygonum amphibium , water-pepper Polygonium hydropiper and tubular water-dropwort Oenanthe fistulosa . The associated dykes and rivers hold a great variety of aquatic plants, the pondweeds Potamogeton spp . are particularly well represented. Other aquatic species include the fringed water-lily Nymphoides peltata , greater water-parsnip Sium latifolium and the four species of duckweeds Lemna spp .

The limnological interest of the Ouse Washes is further diversified by the Old Bedford River and River Delph, both good examples of base-rich, sluggish, lowland rivers. The flora includes the fan-leaved water-crow foot Ranunculus circinatus , yellow water-lily Nuphar lutea , arrowhead Sagittaria sagittifolia , long-stalked pondweed Potamogeton praelongus , perfoliate pondweed Potamogeton perfoliatus , and river water-dropwort Oenanthe fluviatilis . The associated aquatic and semi-aquatic fauna is similarly diverse.

10.9 Overall Screening Opinion

At this stage it is therefore not possible to screen out adverse cumulative water quality effects on a number of designated sites. This issue will therefore require further exploration at the next stage:

• Portholme SAC (water quality),

• Ouse Washes SAC/SPA/Ramsar site/SSSI (water quality),

• The Wash SAC/SPA/Ramsar site/SSSI (water quality),

• Felmersham Gravel Pits SSSI (water abstraction and water quality),

• Stevington Marsh SSSI (water abstraction and water quality),

• Howe Park Wood SSSI (water abstraction),

• Oxley Mead SSSI (water abstraction),

• Blue Lagoon LNR (water abstraction).

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Reduced flows are likely to have an adverse effect on The Wash; siltation resulting from low flows is already recognised as a problem. Given that additional abstraction from the Great Ouse at Milton Keynes is likely to be matched by an increased scale of effluent discharge into the same River and that additional water volume is added to the Great Ouse by the watercourses identified above, it is considered unlikely that increased abstraction at Milton Keynes will lead to significant reduction of freshwater entering The Wash SPA.

Increased flows can lead to prolonged flooding of the Ouse Washes SPA and the spined loach (for which the SAC was designated) is associated with slow flowing watercourses, such that a significant increase in flow rates may render the Ouse unsuitable for the species. However, given that the discharge of treated sewage effluent to the Great Ouse from Milton Keynes is likely to be matched by an increase in abstraction from the same watercourse significant increases in flow are unlikely to occur as a result of any of the expansion areas at Milton Keynes.

High flows may also increase diffuse runoff, and cause bed/bank sediment (together with sediment bound substances such as total phosphorus) to become entrained in the water column. Thus, mobilisation and transport of water soluble and sediment bound substances can be expected during storm events.

The Environment Agency’s Review of Consents has concluded that, although phosphorous levels in the rivers adjacent to The Ouse Washes are considered to be too high at the moment, action at other WwTWs within the Great Ouse catchment should allow the target quality to be met. Funding for the necessary improvements has been made available in AMP4, and all schemes are to be completed by the end of 2009. However, there is nonetheless potential for future development to exceed these standards and potentially make review of other phosphorus sources more desirable.

There is potential for dilution of phosphates contained in treated sewage effluent discharged to the Great Ouse from Milton Keynes due to the four identified tributaries of the Great Ouse upstream of The Ouse Washes SPA or The Wash SPA. However, it is reasonable to conclude that some of these watercourses may themselves carry large loads, or suffer undesirable concentrations of phosphate due to either increased development within the region, and/or due to diffuse sources. Therefore, on a cumulative basis, a possible impact on these European sites cannot be discounted (even though Milton Keynes’ individual contribution may well be small. It is understood that the main Milton Keynes WwTW (Cotton Valley WwTW) is already at the limits of Best Available Technology with regard to phosphate stripping and it may therefore be necessary to further review the contribution of all sources of phosphorus within the River Ouse catchment in order to maintain the target river concentration at the Ouse Washes and The Wash sites.

Since Milton Keynes town is the nearest major urban area upstream of both Felmersham Gravel Pits SSSI and Stevington Marsh SSSI (approximately 30km and 42km upstream, respectively, taking river meanders into account) and since no major watercourses drain to the Great Ouse between Milton

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Keynes and either SSSIs (such that opportunities for dilution are limited) it is reasonable to assume that the new growth areas may contribute to increased phosphorus concentrations of these sites which could potentially lead to adverse effects on the wetland species for which the sites were designated, and increased duration of flooding during periods of high flow. This would need to be investigated further at the next stage.

However, it may well be that after more detailed consideration at the next stage, impacts on many of these sites can be ruled out.

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11 Water Quality / Water Framework Directive

The Water Framework Directive (WFD) was passed into UK law in 2003. The competent authority responsible for its implementation is the Environment Agency in England and Wales.

The overall requirement of the directive is that all water bodies in the UK must achieve “good ecological and good chemical status” by 2015 unless there are grounds for derogation.

The WFD will for the first time combine water quantity and water quality issues together. The link between good physicochemical and ecological status is recognised in the WFD classification system whereby you cannot have one without the other. Whilst the physicochemical standards are important in developing measures to achieve ecological outcomes, it is the sum of the target biological elements that is at the heart of the WFD. The biological elements of ecological status will be expressed as Ecological Quality Ratios (EQR) which expresses observed data compared with type specific reference data.

The WFD combines previous water legislation and in certain areas strengthens existing legislation. An integrated approach to the management of all freshwater bodies, groundwaters, estuaries and coastal waters at the river basin level will be adopted. Involvement of stakeholders is seen as key to the success in achieving the tight timescales set by the directive.

All Water bodies in the UK will be designated a status based on their ecological, and chemical quality. The status will range from poor through to very good and standards are being developed with which to measure this status covering a range of criteria including water quality, biological quality, and morphology. As stated, the aim is for all water bodies to reach ‘good status’ (or good ecological potential in the case of artificial or heavily modified watercourses) or higher by 2015. In order to do so, the Environment Agency in conjunction with the WFD UK Technical Advisory Group (UKTAG) is developing a series of River Basin Management Plans (RBMPs) for the major River Basins of the UK. The RBMPs will be published in draft in 2008 and as final in 2009 and will contain a Programme of Measures which will set out the changes that need to be implemented in order to bring the water bodies which are currently failing the required standards up to good status.

Milton Keynes and its rivers are included in the Anglian River Basin District which covers 27,890 km 2 ranging from Lincolnshire in the north to Essex in the south and Northamptonshire.

The standards are currently in draft form and will not be finalised until the RBMPs are published in late 2009. However, because the WFD requirements will largely superseded the current statutory and guideline environmental standards from 2010, it is important that the WCS considers the requirements for meeting them such that the impact of growth on future compliance with legislative requirements is understood and can be managed at an early stage in the planning. The WCS should also be a driver for improvements in water quality standards.

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Prior to the finalisation of the Anglian RBMP, the EA have undertaken a draft assessment of the characterisation of risk for water bodies in the Anglian River Basin. The summary of the characterisation is shown in Table 11-1.

Table 11-1: Summary of WFD Risk Characterisation, Anglian RBD

Risk factor Watercourse Risk Characterisation

Point source acidification River Ouse and River Ouzel Not at Risk Diffuse and Point source ammonia River Ouse and River Ouzel At Risk Diffuse and Point source BOD River Ouse and River Ouzel Not at Risk Diffuse and Point source Oxidised Nitrogen 21 River Ouse and River Ouzel At Risk Diffuse and Point source Phosphate River Ouse and River Ouzel At Risk Diffuse – mines and minewaters River Ouse and River Ouzel Not at Risk

Whilst the draft risk characterisation is considered to be a broad-brush assessment at this stage in the RBMP process, it does given an indication of the pressures on the two key river systems in and around Milton Keynes. In particular, it lends support to the fact that diffuse and point source nutrient enrichment are a key concern. However, it should be noted that catchment specific investigations and modelling would help to confirm the actual status of the watercourses around Milton Keynes, and determine proportions of loads from each source (point or diffuse, urban or agricultural).

11.1 Water Framework Directive Standards

In terms of water quality standards, the current River RQO and GQA programme has been very successful, particularly in assessing the impact of point source discharges on watercourses. In conjunction with the Urban Wastewater Treatment Directive (UWTD), investment to the larger WwTWs has improved discharges considerably. There are still problems however. In particular, rural sources, especially agricultural diffuse pollution (mainly nutrients, sediment, pesticides), smaller WwTWs, industry, urban areas and roads can cause water quality problems.

In relation to development considered in this WCS, the key concerns are water availability, quantity and quality of runoff from urban areas and roads, and discharges from domestic houses. These can all have a large impact on the water environment, and are interrelated. For example, river flow can affect concentrations of substances such as nitrate. However, existing schemes do not adequately assess the impact of such sources. In particular, they do not quantify the effect on the aquatic environment.

The Water Framework Directive (WFD) classifies water in a different way, using new and revised environmental standards to assess whether environmental conditions are good enough to support appropriate aquatic life for the system in question. The Directive requires that all inland and coastal

21 Total Oxidised Nitrogen is the considered as combined Nitrate and Nitrite.

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water bodies reach at least "good ecological status” by 2015 – subject to certain exemptions, which allow alternative objectives to be set in cases where it is infeasible or disproportionately expensive to achieve good status.

The WFD came into force on 22nd December 2000 (although not enacted into the UK legislative system until 2003), and in accordance with the agreed implementation timetable, monitoring under the Directive commenced on 22nd December 2006. The Directive requires that a draft River Basin Management Plan (RBMP) to maintain or improve the aquatic environment is established by the end of 2008, and updated every six years; the plans will be finalised at the end of 2009 following review by the EC.

It is generally expected that the new classification will reduce the number of waterbodies achieving ‘good ecological status’, since rivers will be graded by the worst parameter of the revised monitoring scheme. The new classification system includes rivers, lakes, estuaries, coastal waters and groundwaters. The WFD requires surface water bodies to be classified into one of five ecological status classes, and one of two chemical status classes. In addition, there are two stages to groundwater classification.

From 2007 to 2009, England and Wales will continue to report results based on the GQA monitoring system, with separate indicators for biology and chemistry. In England, however, a reduced network will be used, so that resources can be re-directed to implementing the WFD monitoring programme. During this time, the existing GQA and WFD approaches will report in parallel. This will enable differences between the two approaches to be distinguished.

The status of each surface water body is judged using separate ‘Ecological classification’ and ‘Chemical classification’ systems. The overall status of the water body will be determined by whichever of these is the poorer. To achieve ‘good status’ overall, a water body must achieve both good ecological and good chemical status.

11.1.1 Ecological classification

The Ecological classification system has five classes, from high to bad, and uses biological, physicochemical, hydro morphological and chemical assessments of status.

• Biological assessment uses numeric measures of communities of plants and animals (e.g. fish and rooted plants).

• Physicochemical assessment documents parameters such as temperature and nutrient concentrations.

• Hydromorphological assessment to document water flow and physical habitat.

As of December 2007, UKTAG had derived standards for some of the more important chemical parameters in freshwaters, as shown in Table 3. The standards will differ based on the ‘typology’ of

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each water body; rivers, lakes, transitional and coastal waters, groundwater. A summary of initial classification for rivers is presented below, based on UKTAG (2007). In this case, just two parameters (dissolved oxygen and phosphorus) are presented as examples, but it is important that studies on water quality bear the full list of new standards in mind. Although the existing GQA scheme is likely to run until 2009, the new standards are being introduced concurrently, and any differences in water quality as a result of the new standards should be fully explored.

The general typology for rivers is based on alkalinity and altitude, as shown in Table 11-2. However, for dissolved oxygen and ammonia, the typology was simplified into just two types, as shown in Table 11-3: . These typologies should be used to define the dissolved oxygen standard for a particular watercourse typology, as shown in Table 11-4: . The standards in Table 11-4: were developed on the basis of oxygen conditions associated with macroinvertebrates, as these are the most sensitive biota to DO.

Table 11-2: Basic typology for rivers (WFD)

Alkalinity (mg/l CaCO3) Site Altitude <10 10 to 50 50 to 100 100 to 200 >200 <80 m Type 3 Type 5 Type 7 Type 1 Type 1 >80 m Type 4 Type 6

Table 11-3: Final typology for oxygen and ammonia for rivers (WFD)

Type Alkalinity Type Upland and low alkalinity Types: (1+2, 4 and 6 Lowland and high alkalinity 22 Types: 3, 5 and 7

Table 11-4: Standards for oxygen in rivers (WFD)

Dissolved oxygen (% saturation)10-percentile Type High Good Moderate Poor Upland and low alkalinity 80 75 64 60 Lowland and high alkalinity 70 60 54 45

The impacts of elevated concentrations of nutrients in freshwater systems, especially phosphorus, are widely studied. The most common impact is enhanced growth of plants and algae, which can affect watercourses in several ways. River channels can become blocked, exacerbating low flow conditions; diurnal fluctuations of oxygen content in the water can occur due to respiration of

22 Where a lowland, high alkalinity water body is a salmonid river, then the standards for the upland, low alkalinity type will apply.

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macrophytes during the hours of darkness, potentially affecting fish; growths of blue-green algae can be stimulated which can cause adverse affects in animals.

For revised nutrient standards in rivers, UKTAG (2007) identified that ecological sensitivity could be related to alkalinity and altitude. The resulting river typology can be seen in Table 11-5: .

Table 11-5: River typology (WFD)

Annual mean alkalinity (mg/l calcium carbonate) Altitude < 50 > 50 < 80 m Type 1n Type 3n > 80 m Type 2n Type 4n

When developing the standards for nutrients in rivers, Guthrie et al (2006) reported that diatoms showed greater sensitivity to nutrients than macrophytes, and these were subsequently used to develop the standards shown in Table 11-6. Also included in Table 11-6, are guideline values produced by the Environment Agency which are commonly referred to, as well as values recommended by the Habitats Directive.

UKTAG (2007) recognise that the relationship between nutrients and water quality is not straightforward. Thus, it is recommended that an indication of ‘actual or potential’ biological impact is needed in addition to a finding of high concentrations of SRP.

Nitrate is already covered by legislation which proscribes a Statutory Limit of 50 mg NO3/l (11.3 mg NO3-N/l) as described previously. However, these limits are largely based on protection of freshwater for the purposes of drinking water. UKTAG (2007) consider that although nitrate may have a role in eutrophication in some types of freshwaters, there is insufficient understanding for new standards or conditions. For this reason, no new standards for nitrate in water have been recommended.

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Table 11-6: Phosphorus standards in rivers under WFD standards, existing GQA guidelines and habitats directive, for comparison

SRP (µg/l) (annual mean) under WFD Type High Good Moderate Poor 1n 30 50 150 500 2n 20 40 150 500 3n & 4n 50 120 250 1,000

Table 11-7: Phosphorus standards in rivers under WFD standards, existing GQA guidelines and habitats directive, for comparison

SRP (µg/l) (annual mean) under existing guidelines 1 2 3 4 5 SRP (µg/l) 20 60 100 200 1,000 Status Very low Low Moderate High Very high

Table 11-8: Phosphorus standards in rivers under WFD standards, existing GQA guidelines and habitats directive, for comparison

SRP (µg/l) (annual mean) under Habitats Directive Headwaters Most rivers Large rivers Natural (1) 0-20 20-30 20-30 Guideline (2) 20-60 40-100 60-100 Threshold (3) 40-100 60-200 100-200

Due to the uncertainty surrounding the effect of applying these revised standards, UKTAG have estimated the change in classification due to the new standards, compared to the old GQA standards for England, Wales and Scotland. When the 95 percent confidence interval is applied to the data presented in Table 11-9, approximately 12% of rivers in England currently fail the existing RQO for either BOD, DO or ammonia. Under the revised standards, this increases to approximately 20%.

It should be emphasised again that that the existing guidance for phosphorus is currently not usually used to base decisions on water quality. More detailed investigations are usually undertaken to demonstrate cause and effect with regards to impact on aquatic ecology.

Table 11-9: Estimated changes to rivers considered ‘less than good quality’ under existing and proposed standards in England

Percent of river length reported as ‘less than good’ BOD Dissolved Oxygen Ammonia Phosphorus Existing Proposed Existing Proposed Existing Proposed Existing Proposed 25.6 18.7 30.8 24.6 14.6 17.3 65 63.3

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11.1.2 WFD and protected areas

The WFD state that ecological status for water bodies under the WFD must be interpreted separately from those standards and objectives set under the legislation for protected areas. Thus, Special Areas of Conservation (SAC) and Special Protected Areas (SPA) must achieve ‘Favourable Conservation Status’. Ideally, this would equate to ‘High Ecological Status’ under the WFD, but in reality the standards and objectives under these designations may differ. Consideration will need to be given on a site-by-site basis. This has particular implications in relation to the Ouse Washes, which are in an unfavourable condition and particularly sensitive to eutrophication as a result of excessive phosphorus.

11.1.3 Chemical classification for priority substances and other pollutants

The Chemical classification system for surface waters, used for the most polluting substances, has only two classes, ‘good’ or ‘failing to achieve good’. We will assess status by checking whether the water meets Environmental Quality Standards (EQSs) for substances listed in Annex IX (Dangerous Substances Directive and associated daughter directives) and Annex X (WFD Priority List Substances). These standards are being set on a Europe-wide basis and are considered a priority because of their high potential for pollution.

11.2 WFD and Milton Keynes

11.2.1 Water Quality in Milton Keynes and Surrounding Areas

There are several existing EA RQO/GQA (now known as River Ecology (RE)) water quality monitoring locations in and around Milton Keynes. Water quality from nine locations on the main watercourses (River Great Ouse and River Ouzel) were summarised and shown in Table 11-10 and Table 11-11.

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Table 11-10: Water quality summary for the River Ouse around Milton Keynes River Ouse River Ecosystem General Quality Assessment

Environment Agency Compliance Chemistry Biology Nitrate Phosphate Sampling Reach 2003- 2004- 2003- 2004- 2003- 2004- 2003- 2004- Target 2005 2006 2005 2006 2002 2005 2005 2006 2005 2006

Reach 1 THORNBOROUGH 3 Y Y B B A A 5 5 5 5 MILL...DEANSHANGER BROOK

Reach 2 DEANSHANGER BROOK 3 Y Y B B A A 5 5 5 5 ..... CONFL. TOVE

Reach 3 3 Y Y B A A A 5 5 5 5 CONFL. TOVE ..... MOTEL

Reach 4 TICKFORD 3 Y Y B A A A 5 5 5 5 ABBEY...SHERRINGTON BRIDGE

Reach 5 SHERINGTON.... 3 Y Y B B A B 5 5 5 5 TYRINGHAM HALL

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Table 11-11: Water quality summary for the River Ouzel around Milton Keynes River Ouzel River Quality Objective General Quality Assessment

Environment Agency Compliance Chemistry Biology Nitrate Phosphate Sampling Reach 2003- 2004- 2003- 2004- 2003- 2004- 2003- 2004- Target 2005 2006 2005 2006 2002 2005 2005 2006 2005 2006

Reach 6 LINSLADE WwTW ..... 3 Marginal Marginal D (DO) D B B 6 6 5 5 STAPLEFORD MILL

Reach 7 STAPLEFORD MILL ..... 3 Y Y B B A B 6 6 5 5 EATON LEYS FARM

Reach 8 3 Y Y C (DO) C C B 5 5 4 4 M1 ..... OUZEL

Reach 9 CONFL. BROUGHTON 3 Y Y B B B B 5 5 5 5 BRK .... BIRCHMOOR FARM

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Key for Tables 11.10 and 11.11 (for full description see Section 6.5.2)

GQA Grades Dissolved Oxygen BOD mg N L -1 (% saturation) mg L -1 Ammonia 90 percentile 10 percentile 90 percentile A 80 2.5 0.25 B 70 4 0.6 C 60 6 1.3 D 50 8 2.5 E 20 15 9.0 F <20 >15 >9.0

Biological Grades Classification Description A - very good Biology similar to that expected for an unpolluted river B - good Biology is a little short of an unpolluted river C - fairly good Biology worse than expected for unpolluted river D - fair A range of pollution tolerant species present E - poor Biology restricted to pollution tolerant species F - bad Biology limited to a small number of species very tolerant of pollution

Nutrient Grades Classification for Grade limit Description phosphate (mg P/I) average 1 0.02 Very low 2 0.06 Low 3 0.1 Moderate 4 0.2 High 5 1.0 Very high 6 >1.0 Excessively high Grade limit Classification for nitrate Description (mg NO3/I) average 1 5 Very low 2 10 Low 3 20 Moderately low 4 30 Moderate 5 40 High 6 >40 Very high

For the recent years (2003 to 2006) the Rivers Great Ouse and Ouzel generally achieved the RQO Grade 3 (‘Moderate Ecological Status’) in all cases. The exception was the River Ouzel, between

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Linslade WwTW and Stapleford Mill, where compliance was ‘marginal’ and the cause was low levels of DO.

Although the River Ouzel achieved RE 3 downstream of the M1, the chemical water quality was fairly good (grade C) for chemistry and biology.

It should be noted that Table 11-10 does not show a significant failure in RQO compliance that occurred between Tickford Abbey and Sherington Bridge (downstream Cotton Valley WwTW) during 2001 and 2003. The cause of this failure was alkaline water.

The most prominent feature of the summary data in Table 11-10 and Table 11-11 are the consistently high nutrient grades for N and P. In the River Great Ouse, the Grades between 2003 and 2006 were always ‘very high’ for phosphate, and ‘high’ for nitrate. In the River Ouzel, the reaches downstream of Linslade WwTW were ‘very high’ for nitrate, but the concentrations of phosphate were slightly smaller (but still ‘high’) than upstream in the reach downstream of the M1 Motorway.

Both the River Great Ouse and the River Ouzel are designated Eutrophic Sensitive Areas under the Urban Wastewater Treatment Directive (91/271/EEC. Where wastewater (treated WwTW Final Effluent) is discharged into these areas, it must undergo a tertiary treatment which reduces its impact on the environment.

Sensitive areas are:

• Natural freshwaters, other freshwater bodies, estuaries and coastal waters which have a large concentration of nutrients. The critical factor is phosphorus which can cause an excessive growth of algae and other plants which can affect species living in the water, and the quality of the water overall. These lakes are called eutrophic. This also covers areas which could become eutrophic if we take no action. These are designated Sensitive Areas (Eutrophic),

• Surface freshwaters used for drinking water that could contain more nitrates than allowed by The Surface Water Abstraction Directive (75/440/EEC). These are designated Sensitive Areas (Nitrate),

• Areas where the water needs treatment additional to secondary treatment to fulfil the requirements of other EC directives. These are designated Sensitive Areas (Bathing Waters) and Sensitive Areas (Shellfish waters).

The EA considers that the WwTW at Cotton Valley in Milton Keynes has the capacity to deal with the increased waste water treatment required to support housing growth (Milton Keynes Council, 2007). However, in liaison with Natural England, MKC has identified two sites that could potentially be affected due to the pathway provided by the River Great Ouse, which flows to the Ouse Washes SPA/SAC. The clear water and abundant macrophytes, is particularly important in the Counter Drain, and a healthy population of spined loach is known to occur. The SPA designation is due to the site’s importance as an internationally important habitat for wetland birds.

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MKC (2007) consider that the distance of Milton Keynes from the Ouse Washes (approximately 60 km) means that any decrease in water quality associated with increased effluent levels would be diluted before it reaches the Natura 2000 sites, meaning the impact will be negligible. This is further supported by the presence of a Development Control Policy in the plan requiring developments to cause no hydrological disturbance. However, the Ouse Washes are in an unfavourable condition, largely due to water quality (excessive nutrients) and excessive flooding (especially summer flooding), thus attention should be given to the role of Milton Keynes water policy as part of a regional strategy to improve water quality upstream of the Ouse Washes. This must also be considered in relation to revised ecological and chemical standards under the WFD, and the status of Protected Areas.

The Ouse Washes is one of two U.K RAMSAR sites to be classified under the Montreux Accord, an alert mechanism to warn the UK Government of potential threats to the area. The potential threats identified are an increase in spring flooding which reduces the wet grassland available to waders for nesting and leads to population decline, and a perceived deterioration in the quality of water from sources that feed the Washes. Increased concentration of some substances; mainly phosphates, but also nitrate, alter habitat conditions with resultant effects on the vegetation and animal communities.

11.2.2 Existing and future standards (dissolved oxygen and phosphorus)

Since the future management of UK rivers is dependant on revised and new standards introduced under the Water Framework Directive, it is appropriate to test some key parameters in order to assess possible compliance issues with ‘Good Ecological Status’. Failure to meet this standard will likely be addressed by measures under draft River Basin Management Plans, to be consulted later in 2008. As previously discussed, these are new standards and have not yet been applied by the EA. The cursory assessment described below is designed as an indication of the impact of two important chemical parameters, namely dissolved oxygen (DO) and phosphorus, in the form of Soluble Reactive Phosphate (SRP).

With regards to new water quality standards under the Water Framework Directive, the reaches of the River Great Ouse and the River Ouzel around Milton Keynes are <80 mAOD, (although a significant proportion of the river is >80 mAOD upstream of Milton Keynes) of and alkalinity is >500 mg/l CaCO3 Thus the river typology is ‘lowland and high alkalinity’

To achieve ‘Good Status’ for DO, the 10-percentile DO content must exceed 60%. Under this analysis, only the River Ouzel between Linslade WwTW and Stapleford Mill would fail to reach ‘Good Status’ for DO (as it did recently under existing chemical GQA Grades).

For phosphorus, the Rivers Great Ouse and Ouzel around Milton Keynes must again be assessed for typology. Both rivers are <80 mAOD, and >50 mg/l CaCO3, and thus comply with Type 3n under the WFD.

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To meet ‘Good Ecological Status’ for phosphate, the standard is 120 µg SRP/l (annual mean). This would place the Rivers Great Ouse and Ouzel in the ‘Poor’ category under the WFD. The sources of phosphorus to water are many and varied, but can be conveniently ascribed to agricultural (grass and arable) and non-agricultural (large WwTW, trade discharges, smaller WwTW and domestic systems). Much investment has been undertaken to improve discharges from major point sources such as larger WwTWs (>10,000 PE), and there is increasing attention given to diffuse sources.

Diffuse source pressures arise from a wide variety of activities. They can arise from land use activities, both rural and urban, that are dispersed across a catchment and may have an individually minor, but collectively significant environmental impact. Examples of diffuse pollution include the transport of nutrients and sediment from farmland or the run-off of water contaminated with pollutants from vehicle emissions from hard surfaces in towns to groundwater and surface waters. Diffuse pollution is often associated with heavy rainfall when pollutants are flushed into watercourses.

Thus the more detailed WCS should undertake a more complete review of water quality pressures. Ideally, this would include areas upstream and downstream of Milton Keynes. Depending on the results of this work, a modelling exercise should be conducted alongside this desk-study, with the objective of estimating the relative loads of phosphorus to watercourses from diffuse and point sources. This exercise would help to determine the relative loads from WwTWs, compared to other sources, and thereby help guide investment decisions.

It should also be noted that under the WFD, more stringent standards might be required for protected areas, in this case the Ouse Washes. Although the distance upstream has been considered to be a mitigating factor for large concentrations of nutrients from up, and downstream of Milton Keynes, any measures to reduce concentrations at the Ouse Washes are likely to require all upstream sources to be reduced to the most practicable loadings/concentrations not exceeding excessive cost. It is recommended that discussions continue with Natural England and EA in order to more fully understand how new standards will be applied, especially in relation to the Ouse Washes, and measures under RBMPs that might impact activities in and around Milton Keynes and its environs.

11.3 WFD and Water Company Planning

An important consideration in the WFD planning process is the timing with respect to the statutory water company planning and funding process. At present, there is a discrepancy between the two planning timelines. The WFD RBMPs are not due to be finalised until 2009 and hence the Programme of Measures which sets out what changes will need to be implemented in order to achieve ‘good’ status in all water bodies, will not be known until this point. Whilst it is not just water companies which will be affected by the programme of measures, it is considered that water companies such as AWS will have a key role to play in implementing the measures and helping to achieve ‘good’ status in time for the 2015 deadline as required by the WFD.

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However, the current PR09 and AMP5 timelines are such that the water companies will be submitting their business plans, which set out the investment requirements for AMP5 (2010-2015), before the RBMPs plans are finalised. It is therefore uncertain how much of the investment required to meet with programme of measures can be planned for and funded in the next AMP period and that much of the investment required to meet good status will not be forthcoming until AMP6 (2015-2020).

Despite this, studies such as the WCS have a role to play in identifying likely impacts of the WFD and where future investment is most likely to be required in order to move key waterbodies towards good status based on the interim risk characterisations. Use of the draft standards and draft risk characterisations is essential such that early decisions can be taken on where investment is most likely to be required in order to meet with the future programme of measures and attainment of ‘good’ status. In this respect, the Milton Keynes WCS can highlight and provide justification for further investment for inclusion in AWS’s submission for PR09 such that measures can begin to be implemented in AMP5 prior to the 2015 WFD target.

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12 Development Area Assessment

Following the assessment of each of the water cycle and water environment topic areas in preceding sections, the constraints and options for water cycle elements relating to the development are covered in the assessment tables which give a visual comparison of each scenario based on a colour coding system. In addition, a textual description of the colour assigned to each scenario is given in the table relevant to each scenario.

The colour coding system used is explained in Table 12-1.

Table 12-1 : Assessment Table Colour Coding

Spare capacity, minimum investment required

Strategic scale mitigation or WSI will be required

Major investment required / major limitation

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12.1.4 Wastewater Drainage and Treatment 12.1 Central Area Cotton Valley WwTW currently receives flows from this area currently has a DWF headroom capable of accommodating approximately 55,560 new properties (based on AWS occupancy of 12.1.1 Overview of Potential Growth 2.1) hence there are no short or medium term constraints in terms of wastewater treatment.

Rapid growth is planned within the Central Area, with the majority of this growth likely to occur on The ongoing works to Cotton Valley WwTW will improve network capacity in many areas an ad-hoc basis, as and when land becomes available. Although there are currently numerous particularly in the centre and east of the city. Development in the Oakgrove area will require developments going forward which are at different phases within the planning process. pumping station and sewer upgrades. Calculations have shown that there are localised issues with Discussions with MKC and MKP have revealed that a maximum of 14,350 homes are proposed for insufficient capacity within the Central Area, particularly in the north-east of the city. this area. 12.1.5 Environment 12.1.2 Flood Risk and Drainage There are a number of conservation areas and wildlife sites within the Central Area, Oxley Mead There are no major fluvial flood risks within this area, although the River Ouzel runs along the SSSI and Howe Park SSSI (and their associated consultation buffers) are located approximately eastern boundary of the area, and Loughton Brook along the western boundary. Localise flash 2km from the limits of the this area. Further screening will be required to determine extent of flooding has been recorded in the SFRA and should be considered a potential issue, and impact of development during the undertaking of the detailed WCS. appropriate mitigation measures should be incorporated into any development. A site-specific assessment of the risks should be undertaken and development located where possible in Flood 12.1.6 Water Quality Zone 1. The SFRA should provide appropriate data for SUDS assessment. Cotton Valley WwTW currently contributes to high phosphate levels in the River Ouzel and River 12.1.3 Water Resources and Water Supply Great Ouse, which in turn affect downstream areas in the Ouse Washes. Therefore any development in this policy area could increase phosphate loads in the watercourses without AWS latest supply/demand balance indicates that this area currently has sufficient deployable technological modifications to the WwTW. This should be addressed as part of the detailed (stage output to meet demand, not allowing for headroom, until 2019/20. Allowing for headroom, this 2) WCS. shows there is already a resource shortfall. This position will be eased in the short term (by 2010) through to developments at Wing WTW (supplied by Rutland Water). Beyond 2010, it may be 12.1.7 Summary necessary to supplement available resources by the development of local schemes with the existing abstraction licence limits. Table 12-2 : Key Development Constraints in Central Area Wastewater In the longer term, a major regional resource development may be required, such as the River Possible Dwelling Environment and Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from Flood Risk Water Resources Scenario Water Quality

adjacent planning zones. East* East* North South Western*

The area is presently serviced by a number of potable water mains and as such servicing should Existing Baseline not be an issue. However AWS have identified that as the existing mains in these areas will not 0-3,500 have been designed for growth on such a large scale significant offsite mains reinforcements may be required. AWS will need to be consulted depending on the total number of properties that can 3,500-7,000 be developed in this area. Consultation with AWS will verify capacities of existing potable water 7,000-10,500 infrastructure. 10,500-14,000**

* Total growth figures have been split across the three sub-areas ** Notionally growth up to 14,350

Final December 2008 127 Milton Keynes Council Water Cycle Study – Outline Strategy

Replace with Figure 12-1

Final December 2008 128 Milton Keynes Council Water Cycle Study – Outline Strategy

12.2.4 Wastewater Drainage and Treatment 12.2 Eastern Area AWS have highlighted that there are significant issues relating to the capacity of the wastewater network serving the area to the South East of Milton Keynes. The inlet works upgrade at Cotton 12.2.1 Overview of Potential Growth Valley WwTW will greatly improve the situation. A broad-scale assessment of the wastewater

Development in the Eastern Area incorporates the Eastern Expansion Area and up to three network has highlighted significant issues in the area around Wavendon, with the system reserve sites as identified in the Local Plan. appearing to be already at capacity. Pressure on the system would be intensified through the development proposed in the Eastern Expansion Area. AWS has significant upgrades proposed Proposed growth within to the east of Milton Keynes would lead to an increase in dwellings of up to serve development in this area with a new trunk main along Broughton Brook which will be to 13,000, plus 53 hectares of non-residential development. Of the 13,000 proposed new extended to the south. dwellings, 5,600 would fall within the administrative area of Mid Bedfordshire District Council. Cotton Valley WwTW currently receives flows from this area currently has a DWF headroom 12.2.2 Flood Risk and Drainage capable of accommodating approximately 55,560 new properties (based on AWS occupancy of 2.1) hence there are no short or medium term constraints in terms of wastewater treatment. There are no significant flood risk issues in the Eastern Area. The River Ouzel runs to the west of the study area and Broughton Brook runs though the study area and there are areas of Flood 12.2.5 Environment Zone 2 and Flood Zones 3a and 3b identified in the SFRA. Risk of groundwater flooding around Woburn Sands site associated with sandy permeable geology. A site-specific assessment of the There are a number of conservation areas and wildlife sites within the Eastern Area, however risks should be undertaken and development located where possible in Flood Zone 1. The SFRA there are no designated environmental protection areas within the proposed growth area, although should provide appropriate data for SUDS. King’s and Baker’s Wood SSSI is approximately 5km south of the limits of the growth area.

12.2.3 Water Resources and Water Supply 12.2.6 Water Quality

AWS latest supply/demand balance indicates that Eastern Area currently has sufficient deployable Cotton Valley WwTW currently contributes to high phosphate levels in the River Ouzel and River output to meet demand, not allowing for headroom, until 2019/20. Allowing for headroom, this Great Ouse, which in turn affect downstream areas in the Ouse Washes. Therefore any shows there is already a resource shortfall. This position will be eased in the short term (by 2010) development in this policy area could increase phosphate loads in the watercourses without through to developments at Wing WTW (supplied by Rutland Water). Beyond 2010, it may be technological modifications to the WwTW. This should be addressed as part of the detailed WCS. necessary to supplement available resources by the development of local schemes with the 12.2.7 Summary existing abstraction licence limits.

Table 12-3: Key Development Constraints in Eastern Area In the longer term, a major regional resource development may be required, such as the River Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from Wastewater adjacent planning zones. Possible Dwelling Flood Risk Water Resources Environment Scenario

The area is presently serviced by a number of potable water mains and as such servicing should North* South* not be an issue, however AWS have identified that significant reinforcements to the current water Existing Baseline supply system will be required to accommodate the planned growth. AWS have a number of strategic upgrade planned as part of the AMP4 and AMP 5 programmes including an upgrade of 0-3,250

Woburn Pumping Station which require the upgrade of the Woburn Pumps, which pump directly 3,250-6,500 into supply as well as the Woburn to Brickhill Copse Pumps which transfer water to Brickhill Copse 6,500-9,750 WTW. Further consultation with AWS will verify capacities of existing and future potable water infrastructure. 9,750-13,000 * Total growth figures have been split across the two sub-areas

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Replace with Figure 12-2

Final December 2008 130 Milton Keynes Council Water Cycle Study – Outline Strategy

Cotton Valley WwTW currently receives flows from this area currently has a DWF headroom 12.3 Western Area capable of accommodating approximately 55,560 new properties (based on AWS occupancy of 2.1) hence there are no short term constraints in terms of wastewater treatment. 12.3.1 Overview of Potential Growth 12.3.5 Environment

Discussions with MKC and MKP have revealed that up to 10,000 new dwellings are proposed There are a number of conservation areas and wildlife sites within the Western Area, Oxley Mead within the Western Area. There are also employment areas and community facilities proposed for SSSI and Howe Park SSSI (and their associated consultation buffers) fall within the limits of the this area. growth area. 12.3.2 Flood Risk and Drainage 12.3.6 Water Quality

There are no significant fluvial flood risks within this area, although Loughton Brook runs along the Cotton Valley WwTW currently contributes to high phosphate levels in the River Ouzel and River eastern edge of the area. The SFRA identifies areas of Flood Zone 2, and Flood Zones 3a and 3b Great Ouse, which in turn affect downstream areas in the Ouse Washes. Therefore any associated with Loughton Brook. A site-specific assessment of the risks should be undertaken development in this policy area could increase phosphate loads in the watercourses without and development located where possible in Flood Zone 1. The SFRA should provide appropriate technological modifications to the WwTW. This should be addressed as part of the detailed WCS. data for SUDS. 12.3.7 Summary 12.3.3 Water Resources and Water Supply

Table 12-4 : Key Development Constraints in Western Area AWS latest supply/demand balance indicates that Western Area currently has sufficient Wastewater deployable output to meet demand, not allowing for headroom, until 2019/20. Allowing for Possible Dwelling headroom, this shows there is already a resource shortfall. This position will be eased in the short Flood Risk Water Resources Environment Scenario term (by 2010) through to developments at Wing WTW (supplied by Rutland Water). Beyond North* North* South* 2010, it may be necessary to supplement available resources by the development of local Central* schemes with the existing abstraction licence limits. Existing Baseline

In the longer term, a major regional resource development may be required, such as the River 0-2,500 Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from 2,500-5,000

adjacent planning zones. 5,000-7,500

The area is presently serviced by a number of potable water mains and as such servicing should 7,500-10,000

not be an issue, as AWS have identified local offsite mains reinforcements to support the planned * Total growth figures have been split across the three sub-areas growth. However AWS will need to be consulted depending on the total number of properties that can be developed in this area. Consultation with AWS will verify capacities of existing potable water infrastructure.

12.3.4 Wastewater Drainage and Treatment

A study of the wastewater network in the study area has revealed there are some issues with the capacity of the existing wastewater drainage network, particularly in the north of the area. AWS is currently reviewing options for serving the Western Expansion Area (Redland development). New pumping stations and sewers will be required to transfer flows to the point of connection into existing main to Cotton Valley WwTW.

Final December 2008 131 Milton Keynes Council Water Cycle Study – Outline Strategy

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Final December 2008 132 Milton Keynes Council Water Cycle Study – Outline Strategy

12.4.4 Wastewater Drainage and Treatment 12.4 Northern Area There are no major issues in the Northern Area. However, a study of the wastewater network has revealed that there are small localised issue in the east of the area where wastewater capacity 12.4.1 Overview of Potential Growth may be insufficient to cope with the future proposed growth. The Northern Expansion Area

Following discussions and input from both MKC and MKP, it is proposed that there will be a total of development framework also states that AWS have said, a pumping station will be needed as 23 up to 3,000 new homes in the Northern Area. there is insufficient fall from the site .

12.4.2 Flood Risk and Drainage (NB From AWS stage 2 report there are no issues with serving Wolverton or Northern Expansion Area) There are no significant fluvial flood risks within this area, although the River Great Ouse flows Cotton Valley WwTW currently receives flows from this area currently has a DWF headroom within the area, and the confluence of the River Great Ouse and River Ouzel is situated in the capable of accommodating approximately 55,560 new properties (based on AWS occupancy of northeast of the area and has experienced flooding in the past. The SFRA identifies areas of 2.1) hence there are no short term constraints in terms of wastewater treatment. Flood Zone 2 and Flood Zones 3a and 3b along the River Ouse. There have been several instances of sewer flooding in Wolverton. There is a low risk of groundwater flooding associated 12.4.5 Environment with an area of more permeable geology to the north of Wolverton. A site-specific assessment of the risks should be undertaken and development located where possible in Flood Zone 1. The There are a number of conservation areas and wildlife sites within the Northern Area, however SFRA should provide appropriate data for SUDS. there are no designated environmental protection areas within the proposed growth area.

12.4.3 Water Resources and Water Supply 12.4.6 Water Quality

AWS latest supply/demand balance indicates that the Northern Area currently has sufficient Cotton Valley WwTW currently contributes to high phosphate levels in the River Ouzel and River deployable output to meet demand, not allowing for headroom, until 2019/20. Allowing for Great Ouse, which in turn affect downstream areas in the Ouse Washes. Therefore any headroom, this shows there is already a resource shortfall. This position will be eased in the short development in this policy area could increase phosphate loads in the watercourses without term (by 2010) through to developments at Wing WTW (supplied by Rutland Water). Beyond technological modifications to the WwTW. This should be addressed as part of the detailed WCS. 2010, it may be necessary to supplement available resources by the development of local 12.4.7 Summary schemes with the existing abstraction licence limits.

In the longer term, a major regional resource development may be required, such as the River Table 12-5: Key Development Constraints in Northern Area Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from Wastewater

adjacent planning zones. Possible Dwelling Flood Risk Water Resources Environment Scenario The area is presently serviced by a number of potable water mains and as such servicing should East* West* not be an issue, however AWS have identified that significant reinforcements to the current water supply system will be required to accommodate the planned growth. AWS have a number of Existing Baseline

strategic upgrades planned as part of the AMP4 and AMP 5 programmes including Old Stratford 0-650 pump upgrades, reinforcement between Old Stratford Pumping Station and Kiln Farm, increasing 650-1,300 storage at Deanshanger water reservoir , and improving resilience of supplies through improving the Salcey to Deanshanger main crossing under the railway. . Further consultation with AWS will 1,300-1,950

verify capacities of existing and future potable water infrastructure. 1,950-3,000

* Total growth figures have been split across the two sub-areas

23 Northern Expansion Area, Development Framework Plan – May 2004 Final December 2008 133 Milton Keynes Council Water Cycle Study – Outline Strategy

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Final December 2008 134 Milton Keynes Council Water Cycle Study – Outline Strategy

Cotton Valley WwTW currently receives flows from this area currently has a DWF headroom 12.5 South Western Area capable of accommodating approximately 55,560 new properties (based on AWS occupancy of 2.1) hence there are no short term constraints in terms of wastewater treatment. 12.5.1 Overview of Potential Growth 12.5.5 Environment

Following discussions and input from both MKC and MKP, it is proposed that there will be up to There are a number of conservation areas and wildlife sites within the South Western Area, Oxley 9,000 new homes in the South Western Area up to 2026 (with 5,390 in Aylesbury Vale). Mead SSSI and Howe Park SSSI (and their associated consultation buffers) are located 12.5.2 Flood Risk and Drainage approximately 1km and 2.5km respectively from the limits of the growth area, with King’s and Baker’s Wood (and Heath’s) SSSI approximately 3.5km from the limits of the growth area. There are no major fluvial flood risks within this area, although Water Eaton Brook flows through 12.5.6 Water Quality the area and the SFRA identifies the associated areas of Flood Zone 2 and Flood Zone 3a and 3b, including parts of Bletchley. There have been instances of sewer flooding recorded in Bletchley Cotton Valley WwTW currently contributes to high phosphate levels in the River Ouzel and River which is situated within the South Western Area. A site-specific assessment of the risks should be Great Ouse, which in turn affect downstream areas in the Ouse Washes. Therefore any undertaken and development located where possible in Flood Zone 1. The SFRA should provide development in this policy area could increase phosphate loads in the watercourses without appropriate data for SUDS. technological modifications to the WwTW. This should be addressed as part of the detailed WCS. 12.5.3 Water Resources and Water Supply 12.5.7 Summary

AWS latest supply/demand balance indicates that the South Western Area currently has sufficient Table 12-6 : Key Development Constraints in South Western Area deployable output to meet demand, not allowing for headroom, until 2019/20. Allowing for headroom, this shows there is already a resource shortfall. This position will be eased in the short Possible Dwelling term (by 2010) through to developments at Wing WTW (supplied by Rutland Water). Beyond Flood Risk Water Resources Wastewater Environment Scenario 2010, it may be necessary to supplement available resources by the development of local schemes with the existing abstraction licence limits. Existing Baseline In the longer term, a major regional resource development may be required, such as the River Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from 0-2,250 adjacent planning zones. 2,250-4,500

The area is presently serviced by a number of potable water mains and as such servicing should 4,500-6,750 not be a major constraint as AWS have identified local offsite mains reinforcements to support the 6,750-9,000

planned growth. However AWS will need to be consulted depending on the total number of * Total growth figures have been split across the two sub-areas properties that can be developed in this area. Consultation with AWS will verify capacities of existing potable water infrastructure.

12.5.4 Wastewater Drainage and Treatment

Study of the wastewater network has revealed there are no major wastewater upgrades required to serve the proposed growth in the South Western Area. Subject to confirmation on capacity, AWS expect the development area to transfer to Cotton Valley via the Loughton Valley trunk gravity sewer. The recently constructed pumping station and rising main to serve Newton Leys would not be of sufficient capacity to serve development of the scale proposed.

Final December 2008 135 Milton Keynes Council Water Cycle Study – Outline Strategy

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Final December 2008 136 Milton Keynes Council Water Cycle Study – Outline Strategy

Cotton Valley WwTW currently receives flows from this area currently has a DWF headroom 12.6 Land East of the M1 capable of accommodating approximately 55,560 new properties (based on AWS occupancy of 2.1) hence; there are no short or medium term constraints in terms of wastewater treatment. 12.6.1 Overview of Potential Growth 12.6.5 Environment

Following discussions and input from both MKC and MKP, it is proposed that there will be up to There are local wildlife sites within this expansion area including Wepener Wood and Moulsoe Old 5,600 new homes in the expansion area east of the M1. Wood. It is not known at this stage whether these sites are hydrologically sensitive to potential 12.6.2 Flood Risk and Drainage changes brought about by the proposed development. Similarly it is not known then exact nature of impact the development will have or neighbouring and downstream designated sites. There are areas of fluvial flood risks within this area associated with Chicheley Brook and the 12.6.6 Water Quality River Ouzel. However, this should not be a major constraint as the EA are unlikely to permit development within flood risk areas.. A site-specific assessment of the risks should be undertaken Cotton Valley WwTW currently contributes to high phosphate levels in the River Ouzel and River and development located where possible in Flood Zone 1. Consideration should be given to the Great Ouse, which in turn affect downstream areas in the Ouse Washes. Therefore any implementation of integrated SUDS measures to attenuate surface water runoff. development in this policy area could increase phosphate loads in the watercourses without 12.6.3 Water Resources and Water Supply technological modifications to the WwTW. This should be addressed as part of the detailed WCS.

AWS latest supply/demand balance indicates that Milton Keynes currently has sufficient 12.6.7 Summary deployable output to meet demand (not allowing for headroom), until 2019/20. Allowing for Table 12-7: Key Development Constraints in Land East of M1 headroom, this shows there is already a resource shortfall. This position will be eased in the short term (by 2010) through to developments at Wing WTW (supplied by Rutland Water). Beyond

2010, it may be necessary to supplement available resources by the development of local Possible Dwelling Flood Risk Water Resources Wastewater Environment schemes with the existing abstraction licence limits. Scenario

.However, AWS have identified that for the Land East of M1, levels of off-site works will be more than for other growth areas since existing mains in that area do not have the capacity to serve Existing Baseline

such major development 0-1,500

AWS will need to be consulted depending on the total number of properties that can be developed 1,500-3,000

in this area. Consultation with AWS will verify capacities of existing potable water infrastructure. 3,000-4,500

12.6.4 Wastewater Drainage and Treatment 4,500-6,000

Study of the wastewater network has revealed there are significant wastewater constraints to the proposed growth in the area east of the M1. The preferred solution is likely to be a direct connection to Cotton Valley WwTW. This would require crossing the M1 motorway. Connection to the existing Newport Pagnell system would require significant upgrades. There are existing flooding issues at Newport Pagnell which would be exacerbated from increased CSO spill frequency.

Final December 2008 137 Milton Keynes Council Water Cycle Study – Outline Strategy

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Final December 2008 138 Milton Keynes Council Water Cycle Study – Outline Strategy

headroom capacity. Consultation should be undertaken with the EA as part of the detailed (stage 12.7 Rural Areas 2) WCS to determine whether the consented limits could be increased. Calculations have shown that there is insufficient capacity in 75% of the network currently serving 12.7.1 Overview of Potential Growth Hanslope, although this may be exacerbated by missing data. Only 15% of the network is shown to have the capacity to facilitate the maximum growth figure for Hanslope (circa 1,500). Data Minor growth of up to 3,000 dwellings is planned within the northern parts of the administrative provided by AWS shows that Hanslope WwTW has an approximate consented flow capacity of area of Milton Keynes. about 755 new dwellings. In the short term the WwTW would be able to cope with the proposed 12.7.2 Flood Risk and Drainage development within Hanslope, however in the longer term (and dependant upon the number of new properties within Hanslope) there may be issues relating to flow capacity at the WwTW. As There is an area of fluvial flood risks within Newport Pagnell, although there are flood risk with Olney WwTW, consultation should be undertaken with both the EA and AWS to determine the management schemes in operation to mitigate this risk. There are no other major flood risk areas scope for increasing consented limits and capacities at Hanslope in order to facilitate the proposed within the rural areas. The areas around Newport Pagnell, Olney and Hanslope are underlain by development. Oolitic Limestone, which poses a groundwater flooding. A site-specific assessment of the risks should be undertaken and development located where possible in Flood Zone 1. The SFRA 12.7.5 Environment should provide appropriate data for SUDS. There are a number of conservation areas and wildlife sites within, or near to Olney and Hanslope. 12.7.3 Water Resources and Water Supply Salcey Forest SSSI, Mill Crook SSSI and Roade Cutting SSSI are within 5.5km of the limits of Olney, with Yardley Chase (and associated extension buffer) within 3km of Hanslope. Hanslope is AWS latest supply/demand balance indicates that the Rural Areas currently has sufficient also within 6km of the Salcey Forest SSSI. deployable output to meet demand, not allowing for headroom, until 2019/20. Allowing for headroom, this shows there is already a resource shortfall. This position will be eased in the short 12.7.6 Water Quality term (by 2010) through to developments at Wing WTW (supplied by Rutland Water). Beyond At this stage it has not been determined in any great detail where the treated effluent from Olney 2010, it may be necessary to supplement available resources by the development of local WwTW and Hanslope WwTW are discharged. However, there are issues relating to discharge to schemes with the existing abstraction licence limits. both ground (via soakaways) or a watercourse. Discharges to ground should examine and In the longer term, a major regional resource development may be required, such as the River determine the exclusion of List 1 and List 2 substances, discharges to a watercourse is likely to Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from increase phosphate loadings. Discharge details should be confirmed as part of the detailed (stage adjacent planning zones. 2) WCS, as well as addressing the prevailing issues.

The area is presently serviced by a number of potable water mains and as such servicing should Although individually small, discharges from rural WwTWs can cause significant local impacts. not be a major constraint. However AWS will need to be consulted depending on the total number The treatment processes are often rudimentary, and often these discharge to small watercourses of properties that can be developed in this area. Consultation with AWS will verify capacities of are not well monitored. Small watercourses can be more sensitive to water pollution and changes existing potable water infrastructure. in water quality than large rivers, and hence the impact from these small works should be assessed at the earliest opportunity. 12.7.4 Wastewater Drainage and Treatment

The wastewater network serving Olney is a pumped system. At this stage it has been assumed that through increasing the pumping rates or pump durations, initial growth in Olney could be handled by the existing system. It is however assumed that through increasing the pumping

phases that the capacity of the wastewater network would not be affected, this would however need to be confirmed during the detailed (stage 2) WCS. Data provided by AWS shows that Olney WwTW (which serves Olney and Emberton) (based on AWS occupancy of 2.1) has no flow

Final December 2008 139 Milton Keynes Council Water Cycle Study – Outline Strategy

12.7.7 Summary

Table 12-8: Key Development Constraints in Rural Areas

Wastewater

Possible Dwelling Flood Risk Water Resources Environment Scenario Olney Hanslope

Existing Baseline

0-750

750-1,500

1,500-2,250

2,250-3,000

* Total growth figures have been split across the two sub-areas

Final December 2008 140 Milton Keynes Council Water Cycle Study – Outline Strategy

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Final December 2008 141 Milton Keynes Council Water Cycle Study – Outline Strategy

13 Water Efficiency

The growth of homes in the Anglian region will place increasing strain on available resources. AWS have already noted this and through existing schemes has already achieved efficiencies through increased metering and reduction of water supply leakage 24 . Meter penetration has reached 57% of AWS’s customers 25 and they have managed to reduce its levels of leakage to 19% of the water put into supply (based on 2005/06) 26 .

13.1 New Development – Water Efficiency

New developments can be built with water efficiency in mind. The CLG have recently consulted on a water efficiency figure for all new builds of between 80 l/h/d and 120 l/h/d.

Approaches to water efficiency differ between the two groups of customers supplied by AWS. The two groups are metered and un-metered customers.

• Metered customers will already be ‘water conscious’ and a typical AWS metered customer uses around 136.9 l/h/d. It can be assumed that these customers will have taken easy steps to improve their water efficiency for example, by mending dripping taps, installing water butts and replacing old washing machines with new more water efficient models,

• Un-metered customers in the Anglian region typically use 155.8 l/h/d. Un-metered households may not be able to afford to switch to a meter (under existing water tariffs) and their options for reducing water usage may be less than for metered customers. Help in the form of a water efficiency audit may be useful step for customers to understand where they might be using most water. The next step may be to provide certain groups of un-metered customers, such those receiving social security payments with small grants to enable households to convert to more water efficient technologies such as showers and low flush toilets.

13.2 Code for Sustainable Homes

The Code for Sustainable homes sets out the maximum water usage permitted for each code level. This provides a flexible outline for improving the overall sustainability of a house. Table 13-1 outlines the water efficiency that needs to be achieved to reach each of the sustainable levels.

24 Anglian Water’s Water Efficiency plan 25 Anglian Water’s Drought Plan. AWS, 2006 26 OFWAT Security of Supply, Leakage and water efficiency 2006/07 report. 4 Water Resources in the South East Forum

Final December 2008 142 Milton Keynes Council Water Cycle Study – Outline Strategy

Figure 13-1: Code for Sustainable Homes – Water consumption targets for the different code levels and examples of how these targets can be attained in new build Code for sustainable Maximum amount of Examples of how to achieve water efficiency level. homes levels. water (litres per person per day)

1 120 Install efficient equipment within the home – 18l max volume dishwasher and 60l max volume washing machine. Install 4/6l dual flush toilets. Install 6-9l/min 2 120 showers. Educate users about how to be efficient water users. Installation of water meters.

3 105 As above. Install flow regulators into bathrooms and kitchens. To reduce flow rate of taps to 3 l/min and showers to a maximum flow rate of 6 l/min. Specify 4 105 ‘low volume’ baths with the levels of overflow pipes at lower than normal levels to prevent over-filling.

5 80 As above, in addition: Grey water recycling for toilet flushing. Provide water audits for people to show them 6 80 where they can reduce water usage.

The examples of water efficiency measures include in are an outline of the possible ways to improve water efficiency. There are many more possibilities that are site specific. Many of these are shown in the OFWAT water efficiency initiatives for water and sewerage companies and it is recommended that these are assessed and considered for inclusion in new development as part of the Stage 2 strategy as the preferred options for development come forward. Other steps which should be considered in new builds include: rainwater harvesting from roofs and paved areas (through the use of permeable surfaces); grey water recycling (with some mains support) which can provide enough water to run all toilets, a washing machine and outside taps.

New developments offer the opportunity to work towards a much higher level of water efficiency, the eco-towns water cycle worksheet shows examples of where community schemes have been used as a way to improve efficiency for example, through the collection and supply of rainwater for use in toilets; these kind of initiatives could be considered for Milton Keynes on a strategic scale to further reduce water demand. The Milton Keynes Framework Agreement for developments in the Eastern and Western Expansion Areas, the Strategic Reserve Areas, Kingsmead South and Tattenhoe Park require 90% of residential development to meet the Eco-Homes ‘Very Good’ standard, and 10% to meet ‘Excellent’. All employment development in these areas should meet the BREEAM ‘Very Good’ standard at least. There is an opportunity to drive these standards up even higher (to Code for Sustainable Homes standards) when it comes to developing standards for new developments in the future.

Final December 2008 143 Milton Keynes Council Water Cycle Study – Outline Strategy

13.3 Current Development – Reducing Existing Baseline

As well as efficiency in new build, consideration should also be given to the options to reduce existing water consumption baseline from existing connections, over and above the measures being implemented by AWS. It is recommended that a detailed water efficiency plan is developed for existing customers in the Stage 2 WCS as an overall plan to reduce the baseline water demand in Milton Keynes. This outline study has initially identified several ways in which current demand can be reduced in Milton Keynes.

Existing homes can achieve significant savings through the retrofitting of efficient devices for example; the installation of 6 litre flush toilets can give a saving of 8% 27 and potentially even more savings with 4.5 litre flush toilets. It should be noted that all new homes being built today are fitted with 6 litre flush toilets as a matter of course today.

There are possibilities within existing development to improve efficiency and reduce the baseline water consumption. Measures that can be employed are:

• Education about water efficiency, in particular about water efficient fixtures and fittings and appliances,

• Advertisement of products and services that can help people to be more water efficient; promote local plumbers who preferable install water efficient fixtures and fittings (for example, provide grants to cover any additional cost for a 4.5 litre toilet rather than a 6 litre toilet),

• Promotion of the Waterwise Marque, which is given to products that show excellent water efficiency. More information can be found at www.waterwise.org.uk ,

• Provision of support for the purchase and installation of water efficient fixtures fittings and appliances such as low flush toilets, efficient dishwashers and washing machines, aerating taps (aerators can be retrofitted on to existing taps), water butts,

• Provide information on lagging pipes to prevent bursts in the winter,

• Provide water audits to show consumers where they use the most water and how they can reduce their water usage,

• Encourage local businesses to promote water efficiency,

• Installing aerators on taps and showers to reduce the amount of water wastage,

• Fit flow restrictors on showers, which reduces flow to a maximum of 8 litres per minute.

Final December 2008 144 Milton Keynes Council Water Cycle Study – Outline Strategy

14 Policy, Developer Guidance and Funding

14.1 Introduction

An important outcome of a completed WCS is to ensure a link between the planning process and the infrastructure required to meet growth requirements. The Stage 2 WCS will define in more detail the infrastructure requirements for the proposed development areas, but a further key outcome will be the timing of implementation of that infrastructure and how it is funded.

The Stage 2 Milton Keynes WCS will ultimately produce a programme or timeline for development with detail of the infrastructure required in order to facilitate this development. The timeline will also demonstrate when funding would need to be sought by AWS as well as the implementation of mechanisms for ensuring sufficient developer contribution towards strategic infrastructure required to meet the requirements of the overall WCS.

It is intended that the completed Milton Keynes WCS will produce an overall strategy that each of the key stakeholders can sign up to. This will aid in the process of delivering development in Milton Keynes and local environs by helping to ensure that objections to proposed development on the grounds of water issues such as flood risk and abstraction are avoided. By producing a completed WCS that is agreed by MKC, AWS, MKPT, IDB and the EA it will aid developers in understanding the requirements they need to meet in order to comply with the strategy produced from the WCS. It will also set the framework for how funding will be sought for the different water infrastructure requirements.

In order to achieve this, the Milton Keynes WCS is required to produce the following:

• Guidance on planning policy with respect to development and the water cycle that MKC can use to input into the LDF, and guidance on incorporating the WCS findings into the Development and Flood Risk SPD,

• Guidance for developers in terms of what developers need to achieve in order to comply with the overall WCS. This will be in the form of a developer checklist and it is envisaged that this will eventually be a document, which if its criterion are all met for a proposed development, will help to ensure no objection from the EA or LPA on the grounds of water cycle issues. This type of checklist document has been successfully developed for other WCS such as the inaugural WCS completed for Corby. Consideration should also be given to the checklist drawn up in the SFRA,

• Agreement on funding mechanisms, particularly for strategic, development wide infrastructure required i.e. strategic scale and integrated surface water attenuation schemes, maintenance and responsibility,

Final December 2008 145 Milton Keynes Council Water Cycle Study – Outline Strategy

• Planning timelines for provision of water infrastructure against growth to aid AWS in planning for water infrastructure within relevant business plans,

• To provide justification for AWS in seeking funding through the PR and AMP process for the required infrastructure,

• Highlight the need for a strategic approach to surface water management e.g. development of Surface Water Management plans across whole areas rather than individual developments.

14.2 Developer Checklist

The overall intention is that all Developers would be asked to use the water cycle developer checklist as part of the planning application process and to submit a completed version with their planning applications. The EA is a statutory consultee with regards to flood risk and the water environment and as such, will need to sign up to the checklist as will MKC. The IDB is the Statutory Operating Authority within its District and is a planning consultee under PPS25. The checklist provided in this Stage 1 WCS (See Appendix F) has been developed from examples used in previous WCS as well as the EA’s national standard checklist available on their website. It is included in the Outline Study as a starting point to further develop in the detailed study, once it is known which development scenarios are to be taken forward.

14.3 Funding and Cost Apportionment Mechanisms

In terms of the overall funding mechanism, it is important to consider that the Government has laid down strict rules on how water companies are funded, especially with regard to domestic development, and the industry’s economic regulator – OFWAT, heavily regulates this overall process. Essentially, AWS has the responsibility for providing wastewater treatment and water supply costs and this is funded through charges to customers within its operating area through the Price Review Process and Asset Management Plan (AMP) process. Therefore, developer contributions relate largely to strategic scale flood management infrastructure (including surface water attenuation).

This Stage 1 WCS report introduces the various policy, funding and developer requirement elements to the Milton Keynes WCS, but it is envisaged that these will be developed further in the detailed Stage 2 WCS.

The Stage 1 WCS has highlighted that there is a need for expenditure on new infrastructure in the following areas:

• Water supply and water resources,

• Wastewater treatment and sewerage,

Final December 2008 146 Milton Keynes Council Water Cycle Study – Outline Strategy

• Large scale surface water management schemes,

• Smaller, site specific surface water management.

Although the options for providing the additional infrastructure will be developed in further detail in the Stage 2 WCS, it is important to consider funding at a strategic level now to inform the development of the Stage 2 WCS.

Both water supply and water resources are the responsibility of AWS within Milton Keynes and as a result, the proportion of which can be charged to developers is set down by agreements with OFWAT. In general, WCS have not considered the apportionment of developer contributions towards strategic water supply and wastewater facilities.

In summary, developers can be included into the financial contribution in two ways:

Stage 1 & 2 - Stakeholder Participation

In developing other WCS’s, property developers have been incorporated into the stakeholder group to provide an input into the direction of the study. It is important to ensure that all developers involved are represented so as to avoid giving any unfair advantage to any one group of developers. In so doing, the developers who are involved would be best placed to undertake the recommendations from Stage 2 of the WCS and ensure that these are incorporated into the design of the developments.

Stage 3 – Infrastructure Funding

Developers may also contribute to the capital works of infrastructure required within the WCS. Although in general this would not apply to wastewater or water supply infrastructure as this is regulated by the Water Companies through OFWAT. It would however include contributions for funding large scale flood risk mitigation measures, with particular emphasis on large scale surface water attenuation storage scheme for development in and around Milton Keynes.

14.3.1 Minimisation of Cost

Despite this, developers can at least contribute to minimising the capital cost of water infrastructure. It can be seen from the assessment of whether existing infrastructure is adequate that a key variable is water consumption per capita. To a large extent developers can be encouraged to reduce this through initiatives such as grey water recycling, having developments with less impermeable surfaces, specifying higher quality materials for pipework etc.

By way of example:

• If the percentage return to sewer can be reduced from 90% to 75%, the number of additional properties that can be accommodated per 1 m3d-1 headroom at an existing WwTW is 0.8.

Final December 2008 147 Milton Keynes Council Water Cycle Study – Outline Strategy

• If reducing the infiltration of groundwater into drains supports the reduction in percentage return to drain by using higher quality drain pipes, the number of additional properties that can be supported per 1 m3d-1 headroom at the same WwTW can be further increased.

14.3.2 Water Resource Provision – Employment

From December 2005, non-household customers who are likely to be supplied with at least 50 mega litres of water per year at their premises are now able to benefit from a new Water Supply Licensing mechanism. If eligible, they may be able to choose their water supplier from a range of new companies entering the market. The Water Supply Licensing mechanism enables new companies to supply water once OFWAT has granted them a licence. These companies can compete in two ways:

• By developing their own water source and using the supply systems of appointed water companies (such as AWS) to supply water to customers' premises. This would be carried out under the combined water supply licence,

• By buying water 'wholesale' from appointed water companies (such as AWS) and selling it on to customers. This would be done under a retail water supply licence.

These are potential options for the sources of employment to be provided in Milton Keynes.

14.3.3 Cost Apportionment Mechanism

The Stage 1 WCS has considered that surface water attenuation will be required in order for new development to comply with PPS25, developers could contribute towards the cost for provision of this on a strategic level. In addition, there are potential options for developer contribution towards strategic sewerage infrastructure provision. Dependent on the options taken forward in the detailed study, a potential charge could be made to developers through the Section 106 mechanism with MKC setting up a fund to receive Developers' contributions and to use them to fund works.

Research for the Corby WCS has identified that there is a legal requirement for such contributions to be made on the basis of commensurate impact of each development, for instance according to its location in the catchment. This mechanism has already been applied in Corby, whereby contributions have been agreed via Section 106 agreements for two key developments; this is an important precedent.

14.3.4 Milton Keynes Tariff System

In Milton Keynes there is a tariff system for new developments in the Eastern and Western Expansion Areas, the Strategic Reserve Sites, Kingsmead and Tattenhoe Park. Tariff payments contribute to the costs of both strategic and local infrastructure. The Tariff system was developed as an approach to manage Section 106 contributions in these areas. Forward funding can be provided by English

Final December 2008 148 Milton Keynes Council Water Cycle Study – Outline Strategy

Partnerships, with repayments being made through subsequent Tariff payments (which are linked to housing completions).

The basis of the system is that each developer pays £18,500 per residential development and £260,000 per hectare of employment land. Milton Keynes Partnership and English Partnerships act as the LPA and banker for the system. The funds are a means of ensuring forward funding is available for key infrastructure including roads, parks, and community facilities such as health centres and schools. Tariff contributions will not cover 100% of the cost of all infrastructure related to growth and other funding sources are still required to make up any shortfall on the provision of local and strategic facilities.

However key benefits of the system are:

• Certainty of a level funding,

• Certainty of developer costs,

• Facilitates MKPs Business Planning,

• Addresses Strategic as well as local infrastructure requirements

• Forward Funding,

• Quality Control.

Outside of the ‘Tariff’ areas MKC continue to negotiate s106 agreements on a site by site basis, using as a starting point the suite of supplementary documents the council has adopted, which set out the basis for developer contributions expected for a range of infrastructure. This current suite of documents includes guidance for developers on Development and Flood Risk. This is based on PPG25, which has now been superseded.

The provision of strategic flood risk infrastructure related to the longer-term growth of Milton Keynes could be incorporated into a future Tariff arrangement on development sites, which would manage any s106 developer contributions. This would need to address all sites across the City, and not just those forming an extension of the city. Any such arrangement would need to be explored with the three Local Planning Authorities as a joint arrangement, as Mid Bedfordshire and Aylesbury Vale do not currently operate a Tariff system, and will have to consider the strategic requirements of other developments in their respective administrative areas.

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15 Conclusions and Recommendations

15.1 Overview

The Stage 1 Milton Keynes Outline WCS has identified the existing capacity of the current water environment and WSI and has used this assessment to determine where additional investment is required to supply new infrastructure or protect the water environment. The conclusions of each assessment are presented here.

15.2 Flood Risk and Drainage

Whilst there is a history of flooding within Milton Keynes and adjacent areas, the EA have confirmed that they would not wish to see new development within the floodplain, and also would not wish to see the construction of new flood risk management infrastructure to purely facilitate new development in areas prone to flooding.

As with any new development there will be an increase in surface water run off, especially where development takes place on Greenfield sites. As MKC has a target of 20% brownfield redevelopment, the majority of development within Milton Keynes will indeed be on Greenfield sites. Any surface water generated as a result of development will be required to be attenuated to Greenfield run off rates, before being allowed to discharge into either watercourses or the AWS surface water system.

Whilst some of the larger expansion areas already have plans in place for the construction of attenuation facilities (i.e. large strategic balancing ponds), other developments would also by required to provide or utilise attenuation facilities. The IDB has expressed concerns associated with the impacts of present design standards and development densities of current growth when compared to the existing surface water and flood risk management assets, which were engineered to different (lower) design/growth standards that were current in the past when the assets were implemented. As whilst there may be calculated capacity in the facilities, taking into account the impacts of climate change and potential changes in flow estimation (since the design of the facilities), the capacity may be less than perceived. The IDB and EA believe that through ‘joined up’ thinking, developers could provide a series of facilities in conjunction with developers of adjacent sites in order to avoid a number of smaller disparate facilities. This would also be the more sustainable option for providing large scale strategic attenuation. The EA also expressed concern that the promotion of smaller localised SUDS techniques are not totally over looked whilst aiming to provide the large scale strategic attenuation, and that the property based SUDS could provide betterment over and above the base standard provided by the strategic SUDS.

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The introduction of small channels and swales to convey surface water to the large scale strategic attenuation facilities would also be a means to extend and/or provide new green corridors into the development areas. Sufficient access for maintenance and maintenance regimes would need to be agreed in advance to determine the size and who would manage the up keep of any new attenuation features (i.e. channels and swales).

Increased development within Milton Keynes will lead to an increase in water demand, which will in turn lead to an increase in the generation of wastewater and ultimately lead to an increase in effluent discharges. Whilst AWS have headroom at Cotton Valley WwTW in terms of the consented volumes of discharge to the River Ouzel, the EA have confirmed that they would not wish to see any increase in discharges to the River Ouzel. It is understood that heavy engineering has been undertaken on the River Ouzel and whilst it is believed that the River Ouzel has capacity to accept additional flows, there are major concerns over increasing flood risk at Newport Pagnell, at the confluence of the River Ouzel and River Great Ouse. Following discussions of the possibility of offsetting increases in effluent discharges with an equal decrease in surface water discharge (from Willen Lake), the following statement has been agreed between the EA and AWS and will provide guidance on this issue.

As there is no surface water (open channel and sewer) network model, it may be prudent to develop a model either as part of Stage 2 of the WCS, or as part of any future Surface Water Management Plan (SWMP), which MKC may be required to undertake.

15.3 Water Environment

The discussion in Section 6.5.1 described Water standards, discharge requirements, and other sources of substances such as phosphorus, while Section 11 described existing water quality in the Milton Keynes area, before outlining some possible effects of applying some new standards under the Water Framework Directive. Possible impacts of nearby and downstream designated sites were also highlighted.

This initial assessment has not been able to assess the ‘water quality’ capacity of the watercourses in and around Milton Keynes since process capacity at key WwTWs are currently being reviewed by AWS.

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The Statutory standards for ammonia and DO should be fully considered as part of this review. However, the consistently high nutrient grades for N and P in the Rivers Great Ouse and Ouzel. Both are designated Eutrophic Sensitive Areas under the Urban Wastewater Treatment Directive (91/271/EEC). Where wastewater (treated WwTW Final Effluent) is released into these areas, it must undergo a secondary treatment which causes less impact on the environment.

However, there are also several smaller WwTWs in the Milton Keynes area, up and downstream. Discharges from small WwTWs can impact smaller watercourses (or groundwater in the case of soakaways). The possible impact of these discharges (and any possible increases in discharge) on receiving surface, and/or groundwater should not be overlooked.

Diffuse source pressures also represent a significant threat to water quality. Diffuse sources arise from a wide variety of activities. They can arise from land use activities, both rural and urban, that are dispersed across a catchment and may have an individually minor, but collectively significant environmental impact. Examples of diffuse pollution include the transport of nutrients and sediment from farmland or the run-off of water contaminated with pollutants from vehicle emissions from hard surfaces in towns to groundwater and surface waters. Diffuse pollution is often associated with heavy rainfall when pollutants are flushed into watercourses.

The screening exercise undertaken as part of Section 10 showed that any adverse effects of the Milton Keynes growth areas on a number of sites could not be screened out. These would therefore need more consideration during the detailed (stage 2) WCS:

• Portholme SAC (water quality),

• Ouse Washes SAC/SPA/Ramsar site/SSSI (water quality),

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• The Wash SAC/SPA/Ramsar site/SSSI (water quality),

• Felmersham Gravel Pits SSSI (water abstraction and water quality),

• Stevington Marsh SSSI (water abstraction and water quality),

• Howe Park Wood SSSI (water abstraction),

• Oxley Mead SSSI (water abstraction),

• Blue Lagoon LNR (water abstraction).

However, it may well be that after more detailed consideration at the next stage, impacts on many of these sites can be ruled out.

15.4 Wastewater Treatment and Transmission

The high levels assessments have identified that there are a number of capacity issues within the wastewater network serving Milton Keynes. Through increasing levels of development, any existing issues relating to capacity would be exacerbated. This could however be managed either through providing upgrades to the existing network at known problem areas (i.e. increasing the size of pipework) or in certain development areas concentrating development around parts of the network where there are less capacity issues.

This is particularly true in the Central Area and the Northern, Western and Eastern development Areas. From the broadscale wastewater network capacity calculations, parts of the systems undertaken as part of this study, these areas have been shown to potentially have capacity issues, whilst parts of the system serving of areas within the same development areas have capacity issues of a lesser. This should be confirmed by network modelling as part of the scope of works for the detailed WCS.

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Table 15-1: Wastewater Network – Constraints Summary Area Sub Area Constraint North East Major Central South East Significant West Significant South Major Eastern North Minor North Major Western Central Significant South Minor East Significant Northern West Minor South Western Minor Land East of M1 Major Olney Major Rural Hanslope Major

In the short term, phasing of development could be concentrated on areas with the least initial constraints (i.e. northern part of Eastern Area, southern part of Western Area, western part of Northern Area and South Western Area). Infrastructure upgrades would then allow development in other areas, where greater constraints have been highlighted. Confirmation of site-specific constraints should be determined through network model during the Detailed WCS. Consideration must also be given to the cumulative effect of development in shared networks (i.e. the impact of development in the west of the Central Area, Western Area and Northern Area, upon the lower part of the system).

Discussions will also be required to determine whether there is scope to increase discharges at Olney WwTW and Hanslope WwTW, both of which are either at or close to their consented limits. Cotton Valley WwTW will also need consent increase within LDF period (unless major reduction in water consumption).

15.5 Water Resources and Water Supply

Milton Keynes is presently supplied by Wing and Grafham WTWs, which are in turn fed from Rutland Water and Grafham Water respectively.

The forecast growth in demand for 57,950 new homes (by 2026) is estimated at 17 Ml/d for residential demand and a further 9 Ml/d for non-residential development. The latter demand is likely to be from commercial and service based industry. The combined total is approximately 26 Ml/d on average but could be as high as 29 Ml/d on average. These figures exclude a 30% allowance for

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headroom which is considered sensible to plan for. In addition, the above estimates do not take into account of the Marston Vale Eco-Town, which could draw upon an extra 6 Ml/d.

AWS latest supply/demand balance indicates that the Milton Keynes and Newport Pagnell area currently only have sufficient DO to meet demand, not allowing for headroom, until 2019/20. Allowing for headroom, this shows there is already a resource shortfall. This position will be eased in the short term (by 2010) through developments at Wing WTW (supplied by Rutland Water). Beyond 2010, it may be necessary to supplement available resources by the development of local schemes, such as at Foxcote WTW, within the existing abstraction licence limits. In addition, phased developments at Clapham WTW will release DO from Grafham Water to supply Milton Keynes, although this may require an increase in the abstraction licence at Clapham (on the River Bedford Great Ouse).

In the longer term, a major regional resource development may be required, such as the River Trent Transfer Scheme. As part of this scheme, there will be the re-zoning of supplies from adjacent planning zones. The mitigation measures being put in place at the Rutland Water SPA, such as the creation of wetland habitats, should enable full take-up of this licence quantity without any negative effects on the site.

There are however a number of other uncertainties (i.e. climate change, the review of consents and Water Framework Directive), which remain and may affect the water resources situation in the future and the status of available growth within the Milton Keynes area. The WCS is an iterative process and will be updated periodically

15.6 Milton Keynes Tariff System

In order to assist with the provision of required water services infrastructure to help maintain the proposed growth within Milton Keynes, we would recommend that the existing tariff system is continued and developed. However this should be further investigated across the three Local Planning authorities, as the Tariff currently only operates in the MKC administrative area.

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16 References

Anglian Water – Drought Plan, 2006 Anglian Water – Water Efficiency Plan, 200 4 Anglian Water – 2005 Water Resources Management Plan, 2004 Anglian Water – 2009 [Draft] Water Resources Management Plan, 2008 Anglian Water – 2009 Water Resources Management Plan, 2008 Anglian Water website – www.anglianwater.co.uk Communities and Local Government – Code for Sustainable Homes - Step-change in sustainable home building practice, 2006 Communities and Local Government – Code for Sustainable Homes – Technical Guide, 2007 Communities and Local Government – [Draft] South East Plan, 2006 Communities and Local Government – Planning Policy Statement 25: Development and Flood Risk, 2006 Communities and Local government, Department for Environment, Food and Rural Affairs – Water Efficiency in New Buildings, 2007 http://www.communities.gov.uk/documents/planningandbuilding/pdf/WaterEfficiencyNewBuildings Communities and Local Government, Environment Agency, Town and Country Planning Association – Sustainable Water Management: Eco-towns Water Cycle worksheet, 2008 CIRIA – Dry Weather Flow in Sewers, 1998 David Locke Associates – Brooklands Development Brief, 2006 David Locke Associates – Broughton Gate Development Brief, 2005 Department for Environment, Food and Rural Affairs – Securing water for the future, press release, 2008 http://www.tcpa.org.uk/press_files/pressreleases_2008/20080325_ET_WS_Water.pdf Department for Environment Food and Rural Affairs website – http://www.defra.gov.uk/default.htm Environment Agency – Guideline phosphorus standards for SAC rivers. Water Quality Task Group for the Habitats Directive. WQTAG048b, 2002 Environment Agency – River Great Ouse Catchment Flood Management Plan – Consultation Draft Plan, 2007 Environment Agency – SUDS, A Practical Guide, 2006 Environment Agency – The Upper Ouse and Bedford Ouse CAMS, 2005 Environment Agency – Towards Water Neutrality in the Thames Gateway, Summary Report, 2007 Environment Agency website – http://www.environment-agency.gov.uk/ Environment Agency, Department for Environment, Food and Rural Affairs – Preliminary rainfall runoff management for developments, R&D Technical Report W5-074/A/TR/1 Revision D, 2007 Environment Agency, Natural England and Partners – Planning Sustainable Communities: A Green Infrastructure Guide for Milton Keynes and the South Midlands, 2005 Gazeley UK – Nova Devlopment Brief, 2005 Government Offices for the South East – Milton Keynes and South Midlands Sub-Regional Strategy, East Midland East of England, 2005

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Guthrie, Duncan and Owen – The development of soluble reactive phosphorus regulatory values in UK rivers. Paper prepared for UKTAG Rivers Task Team, 2006 Halcrow – Drainage Strategy for Milton Keynes, 2004 Halcrow – Eastern Expansion Area Development Framework, 2005 Halcrow – Milton Keynes Level 1 Strategic Flood Risk Assessment, 2008 Halcrow – Water Cycle Strategy Draft Guidance, Version 1 Revision 2, 2008 Institute of Hydrology – Flood Estimation Handbook (FEH) – Vols 1 -5, 1999 Joint Nature Conservation Committee website – http://www.jncc.gov.uk/page-0 Milton Keynes Council – Northern Expansion Area Development Framework SPG, 2004 Milton Keynes Council, Milton Keynes Partnership – Western Expansion Area Development Framework, 2005 Milton Keynes Partnership – The New Plan for Milton Keynes: A Strategy for Growth to 2031, 2006 Multi-Agency Geographic Information for the Countryside website – http://www.magic.gov.uk/# The Office of Water Services – Security of Supply, Leakage and Water Efficiency (2006/07), 2008 The Office of Water Services – Water Efficiency Initiatives – Good Practice Register Water Sewerage Companies, 2006 http://www.ofwat.gov.uk/aptrix/ofwat/publish.nsf/AttachmentsByTitle/goodpracticeregister_2007.pdf/$ FILE/goodpracticeregister_2007.pdf United Kingdom Technical Advisory Group – UK Environmental Standards and Conditions (Phase I) Update report . UK Technical Advisory Group on the Water Framework Directive, 2007 Woods Hardwick – Broughton Park Development Brief, 2006 WRc plc – Sewers for Adoption, 2006 WSP – Land South of A421 Flood Risk Assessment, 2007 WSP – Stoke Goldington Flooding Investigation, 2007

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Appendix A – Data Requests

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Appendix B – Wastewater Network Capacity Calculations

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Appendix C – DWF Calculations

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Appendix D – Hydrological Analysis

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Appendix E – SUDS Options Details

Milton Keynes has been developed around the concept of strategic and integrate surface water and flood risk management, with large flood storage reservoirs and engineered watercourse. The Drainage SPG states growth must provide strategic and integrated drainage systems. Therefore Strategic and Integrated drainage and SUDS is essential to continue the success of Milton Keynes.

Soakaways

Soakaways are traditionally built as square or circular pits, either filled with rubble or pre-cast perforated concrete pipes surrounded by suitable granular backfill (although their design and depth may vary depending on area draining into them). Their use is generally subject to full infiltration testing.

There are a number of factors that should be considered prior to their inclusion in drainage design, such as:

• Relevant guidelines (such as BRE Digest 365) require that any soakaways should be constructed at least 5m from any building foundations. Dependent on the layout of sites in relation to their topography, this building restriction could limit the use of soakaways on some terraces or blocks of dwellings,

• In areas of steep topography of the site, soakaways should be aligned perpendicular to the slope direction, i.e. they should be ‘contoured’,

• In areas of steep gradient, allowing water to freely infiltrate into surrounding ground may cause ground slumping, soil creep or similar effects.

Swales

Swales are shallow ditches designed to conduit and retain water, as well as facilitate infiltration where possible. Where ground conditions are suitable, infiltration will occur either naturally or via a filter drain located beneath the swale base. This can be filled with granular material and, if necessary, a perforated or half perforated pipe. Swales typically are grass covered but can also contain larger vegetation types (often scrub or reeds). This vegetation can aid water attenuation through encouraged evapotranspiration, uptake or infiltration. It can also reduce water velocities and filter particulate matter, such as hydrocarbons and particulate matter. Given these properties, they are typically located adjacent to roads or parking areas. Their efficiency of infiltrating water into underlying ground is dependant on full infiltration testing.

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Swales are likely to be suitable for receiving surface water runoff generated from roads and communal parking areas. They could also be used to collate water from roofs in areas where soakaways are not available.

Permeable Surfacing

Permeable surfacing involves the use of permeable material in the place of impermeable surfacing. This is typically used for roads or parking areas. Where ground conditions are suitable, permeable paving allows infiltration into the surrounding ground, using a permeable sub base. Where conditions are not suitable, permeable paving can act as medium into a sub-surface attenuation tank beneath the paving from which it is discharged through to the sewer system at an agreed restricted rate, using a hydrobrake or similar.

There are a number of mediums that can be used in the attenuation facility including:

• Tanked systems whereby reinforced tanks situated beneath the permeable surfacing are located. Their design should considered significant loadings from vehicular traffic,

• Granular fill typically has a void ratio of 0.3 (30%) and is readily available as graded gravel fill,

• Crate systems have a higher void ratio (up to 90% in some cases) but are often costly and may require complex maintenance.

Depending on potential adoption issues, permeable paving has the potential to be used for all access roads and parking areas. The choice of system is dependant on the permeability of the underlying ground and therefore upon full infiltration testing of the underlying ground.

Detention Basins or Retention Ponds

Detention basins are depressions (often vegetated for landscape purposes) that are normally dry but allow storage of storm water to attenuate surface flows. Should ground conditions be suitable, infiltration will occur naturally. Retention ponds are similar to detention basins but retain a permanent level of water. If situated in permeable soil conditions, the base of the pond may require lining. Discharge from retention or detention ponds into the receiving watercourse can be through a pipe or overflow system.

These features may have wider benefits beyond flood risk by reducing the amount of pollutants or suspended material present in any potential outflows. In addition, they can add to the amenity and biodiversity value of a development (this is particularly relevant for retention ponds).

Other Methods

Other typical SUDS methods include techniques such as greenroofs, water harvesting, wetlands, filter drains and filter strips. They are potentially viable options for the proposed site and can have wider

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sustainability benefits. However they do not generally constitute a significant volumetric input into attenuation.

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Appendix F – Developer Checklist

Key Water Cycle strategy Recommended Policy Environment Agency and Natural England policy and recommendations Local Policy National Policy or Legislation

Policy No. Flood Risk Assessment requirement checklist Answer /Legislation 1 Is the Development within Flood Zones 2 or 3 as defined by the Y - go to 5 flood zone mapping in the Milton Keynes SFRA? N - go to 2

2 Development is within Flood Zone 1: • Site larger than 1 Ha? go to 5 • Site smaller than 1 Ha? go to 3

3 Is the development residential with 10 or more dwellings or is the Y - go to 6 site between 0.5Ha and 1Ha? N - go to 4

4 Is the development non-residential where new floorspace is Y - go to 6 1,000m 2 or the site is 1 Ha or more? N - go to 7

5 The development constitutes major development or lies within Go to 8 Flood Zone 2 or 3 and requires a Flood Risk Assessment (in accordance with PPS25 and the Milton Keynes SFRA) and the Environment Agency are required to be consulted.

PPS25 6 The development constitutes major development and is likely to Go to 8 require a Flood Risk Assessment (in accordance with PPS25 and the Milton Keynes SFRA) but the Environment Agency may not be required to be consulted.

7 An FRA is unlikely to be required for this development, although Y – go to 8 a check should be made against the Milton Keynes SFRA and N – go to 9 with Milton Keynes Council to ensure that there is no requirement for a FRA on the grounds of critical drainage issues. Does the SFRA or do Milton Keynes Council consider than an FRA is required?

8 Has an FRA been produced in accordance with PPS25 and the Y/N or N/A Milton Keynes SFRA?

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Policy No. Surface water runoff Answer /Legislation 9 A) What was the previous use of the site? EA Requirement for B) What was the extent of impermeable areas both before and % before % FRA. after development? after 10 If development is on a Greenfield site, have you provided Y/N or N/A evidence including calculations that post development run-off will not be increased above the Greenfield runoff rates and volumes using SUDS attenuation features where feasible (see also 18 onwards).

If development is on a brownfield site, have you provided Y/N or N/A evidence including calculations that the post development run-off rate has not been increased, and as far as practical, will be PPS25 decreased below existing site runoff rates using SUDS attenuation features where feasible (see also 17 onwards).

Where a previous connection was made to a combined sewer, AWS are encouraging developers to dispose of surface water by an alternative means. Developers no longer have the right to connect.

11 Is the discharged water only surface water (e.g. not foul or from Y/N Water Resources highways)? Act 1991

If no, has a discharge consent been applied for? Y/N

12 A) Does your site increase run-off to other sites? Y/N PPS 25 Preliminary Rainfall B) Which method to calculate run-off have you used? Runoff Management for Developments and the Interim Code of Practice for SUDS 13 Have you confirmed that any surface water storage measures Y/N PPS25 are designed for varying rainfall events, up to and including, a 1 Preliminary Rainfall in 100 year + climate change event (see PPS25 Annex B, table Runoff B.2)? Management for Developments and the Interim Code of Practice for SUDS 14 For rainfall events greater than the 1 in 100 year + climate Y/N change, have you considered the layout of the development to ensure that there are suitable routes for conveyance of surface flows that exceed the drainage design? PPS25 Guidance Notes 15 Have you provided layout plans, cross section details and long Y/N section drawings of attenuation measures, where applicable?

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16 If you are proposing to work within 9 m of a watercourse have Y/N or N/A Water Resources you applied, and received Flood Defence Consent from the EA? Act 1991 Land Drainage Act 1991 EA Land Drainage and Sea Defence Byelaws enforceable under Water Resources Act 1991 17 If you are proposing any culverting of watercourses have you Y/N or N/A Land Drainage Act applied for consent from the EA/IDB. If a development is within 1991 the Board’s district or drains to the Board’s district, a developer needs to liaise with the IDB for all development 18 The number of outfalls from the site should be minimised. Any Y/N Guidance Driven by new or replacement outfall designs should adhere to standard the Water guidance form SD13, available from the local area Environment Resources Act Agency office. Has the guidance been followed? 1991

Policy No. Sustainable Drainage Systems (SUDS) Answer /Legislation 19 A) Has the SUDS hierarchy been considered during the design Y/N of the attenuation and site drainage? Provide evidence for reasons why SUDS near the top of the hierarchy have been disregarded.

B) Have you provided detail of any SUDS proposed with supporting information, for example, calculations for sizing of features, ground investigation results and soakage tests? See

CIRIA guidance for more information. PPS25 Guidance http://www.ciria.org.uk/SUDS/697.htm

20 A) Are Infiltration SUDS to be promoted as part of the Y/N development? If Yes, the base of the system should be set at least 1m above the groundwater level and the depth of the unsaturated soil zones between the base of the SUDS and the groundwater should be maximised. Notwithstanding this, soakaways and other infiltration devices should be no deeper than 2m unless otherwise agreed in writing with the Environment Y/N Agency.

B) If Yes – has Infiltration testing been undertaken to confirm the effective drainage rate of the SUDS?

21 A) Are there proposals to discharge clean roof water direct to Y/N ground (aquifer strata)?

B) If Yes, have all water down-pipes been sealed against Y/N pollutants entering the system form surface runoff or other forms of discharge?

22 Is the development site above a Source Protection Zone (SPZ)? If Y go to 22 Groundwater If N go to 23 Regulations 1998

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23 A) Is the development site above an inner zone (SPZ1)? Y/N Groundwater Regulations 1998 B) If yes, discharge of Infiltration of runoff from car parks, roads Y/N and public amenity areas is likely to be restricted – has there been discussion with the EA as to suitability of proposed infiltration SUDS? 24 A) For infill development, has the previous use of the land been Y/N considered?

B) Is there the possibility of contamination? Y/N

PPS23 C) If yes, infiltration SUDS may not be appropriate and Y/N remediation required to be undertaken. A groundwater Risk Assessment is likely to be required (Under PPS23) Has this been undertaken before the drainage design is considered in detail? 25 Have oil separators been designed into the highway and car Y/N PPG23 parking drainage? PPG23: http://publications.environment- agency.gov.uk/pdf/PMHO0406BIYL-e-e.pdf

26 Have you confirmed whether the proposed SUDS are to be Y/N adopted as part of public open space, or by a wastewater undertaker and provide supporting evidence?

Alternatively, have you provide details of the maintenance Y/N contributions to be provided over the life of the development. 27 Have you provided details of any proposed measures to Y/N encourage public awareness of SUDS and increase community participation?

Policy No. Water Consumption Answer /Legislation 28 A) Have you provided the expected level of water consumption Y/N and hence the level to be attained in the Code for Sustainable Homes http://www.planningportal.gov.uk/england/professionals/en/1115 314116927.html B) Have you considered whether the development can achieve a water consumption lower than 120 l/h/d (105 l/h/d for Levels 3 & 4 in the Code for Sustainable Homes, 80l/h/d as required for Levels 5 & 6)

29 Is the proposed development likely to achieve a water Y/N consumption of between 120 l/h/d and 135 l/h/d as consistent with the latest DEFRA strategy? http://www.defra.gov.uk/environment/water/strategy/pdf/future- water.pdf

30 Have you Provided details of water efficiency methods to be Y/N installed in houses?

31 Have you confirmed whether the development will utilise Y/N rainwater harvesting (minimum tank size 2.5m 3 per house, see http://www.environment- agency.gov.uk/subjects/waterres/286587/286911/548861/86159 9/?lang=_e

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32 Has a practicable alternative strategy been included for the Y/N supply of water for fire fighting?

33 Have you confirmed whether grey water recycling is to be utilised Y/N and provided details?

34 Have you provided details of any proposed measures to increase Y/N public awareness and community participation in water efficiency?

Policy No. Pollution prevention Answer /Legislation 35 Have you provided details of construction phase works method Y/N PPG2, PPG5, statement, outlining pollution control and waste management PPG6, PPG21 measures? See PPG2, PPG5, PPG6, PPG21 (http://www.environment- agency.gov.uk/business/444251/444731/ppg/?version=1&lang=_ e ) and DTI Site Waste Management Plan, (SWMP, http://www.constructingexcellence.org.uk/resources/publications/ view.jsp?id=2568 )

36 A) Have you provided details of pollution prevention measures Y/N for the life of the development, such as oil and silt interceptors?

B) Have you considered whether permeable pavement areas are protected from siltation? Y/N

C) Have you provided details of maintenance – as with the SUDS? Y/N

Policy No. Water Supply and Sewage Treatment Answer /Legislation 37 Have you provided evidence to confirm that water supply Y/N capacity is available, and that demand can be met in accordance with the Milton Keynes Stage 1 WCS?

38 Have you provided evidence to confirm that sewerage and Y/N wastewater treatment capacity is available, and that demand can be met in accordance with the Milton Keynes Stage 1 WCS?

Policy No. Conservation / Enhancement of Ecological Interest Answer /Legislation 39 Have you confirmed that any green infrastructure, such as the Y/N Green surface water system, links to the neighbouring green Infrastructure Study infrastructure (River Corridors) to assist the creation and maintenance of green corridors?

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40 Have you confirmed that at least 25% of flood attenuation Y/N ponds/wetlands will be designed for multifunctional uses, such as providing access, footpaths, cycleways, recreational uses, and submit outline details as suggested under Natural England guidelines?

41 A) Have you shown the impacts your development may have on Y/N the water environment? Town and Country Planning B) Is there the potential for beneficial impacts? Y/N Regulations 1999.

42 Have you confirmed all ponds within 500m of the site boundary Y/N Habitats Directive have been surveyed for presence of great-crested newt populations?

Further information can be found in the EAs guide for developers - http://www.environment- agency.gov.uk/business/444304/502508/1506471

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