Detailed Water Cycle Study Last modified date: July 2011
This document has been produced by Peter Brett Associates LLP in partnership with East Hampshire District Council, in support of the proposed Whitehill Bordon Eco-town. Peter Brett Associates LLP Caversham Bridge House Waterman Place Reading Berkshire RG1 8DN TEL: 0118 9500761 FAX: 0118 9597498
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Whitehill Bordon Eco-town Detailed Water Cycle Study: July 2011
Index CONTENTS Executive Summary, 6 1 Introduction, 11 1.1 Purpose, 15 1.2 Eco-town, 17 1.3 Scope of Study, 19 2 Outline Study, 20 2.1 Scope of Study, 21 2.2 Recommendations, 21 2.3 Moving Forward, 22 3 Legislation & Policy, 22 3.1 European and National Legislation, Policy and Guidance, 23 3.2 Regional Policy and Guidance, 31 3.3 Local Policy, 33 4 Water Neutrality, 35 4.1 Achieving Neutrality, 36 4.2 Defining the Zones, 38 4.3 Stakeholders, 45 5 Environmental Protection, 45 5.1 Designated Sites and Habitats, 46 5.2 Water quality, 49 5.3 Pollution control, 52 Water Resources, 55 6.1 Groundwater, 56 6.2 Surface Water, 62 6.3 Rainwater, 64 6.4 Flooding, 66
7 Water Demand Modelling, 68 7.1 Description, 69 7.2 Scenarios, 72 7.3 Results, 74 7.4 Summary, 79 8 Drainage Options, 80 8.1 Surface Water, 81 8.2 Green Infrastructure, 88 8.3 Foul Sewerage, 91 9 Supply & Treatment, Treatment, 93 9.1 Water Supply, 94 9.2 Water Reuse, 94 9.3 Metering & Tariffs, 103 9.4 Town Water Company, 104 9.5 Retrofitting, 106 10 Legislation & Regulations, 108 10.1 Introduction, 108 10.2 Primary measures - Legislation, 108 10.3 Secondary measures - Regulations, 109 10.4 Tertiary measures - Local measures, 110 11 Recommendations Recommendations & Further Investigations, Investigations, 111 11.1 Recommendations & Design Guidance, 112 11.2 Proposed Policy, 121 11.3 Behavioural Change, 124 11.4 Further Studies, 128 11.5 Water Neutrality, 130 Glossary,134 Glossary,134 References, References, 137 Appendices, Appendices, 139
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FIGURE LIST
TABLE LIST
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13
Table 1 Qualitative assessment of pollution risks, 53
Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24
Different stages of a water cycle study, 15 Water Hierarchy in Development, 17 Water Management Zones within Eco-town Boundary, 18 Conceptual ‘Water Neutral’ Streetscape, 37 Watersheds and drainage direction, 39 EA GSPZ Mapping for Bordon, 41 EA’s current mapping of ecological quality for rivers,50 SEW Resource Management Zone 5, 57 Extract of Resource Management Zone 5, 58 Surface Water & Unconfined Groundwater Availability, 61 Seasonal Mean Precipitation Trends by 2080s, 65 Conceptualisation of water demand model, 69 Water consumption patterns for a domestic property as proportion of total use, 71 Conceptualisation of the benefits of using green water, 72 Monthly Demand Split, 73 All Systems Operational, 75 Dual Systems Operational, 76 Singular Systems Operational, 77 Climate Change Rainfall Profiles, 78 Attenuation Basin and Infiltration blanket arrangement Angmering, West Sussex, 85 Possible Water Arrangements, 106 The Local Loop - Conceptual Diagram of Water Supply Network, 116 Green Water Pipe - Conceptual Diagram, 123 Approaches to tackling Behavioural Change, 126
Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 11 Table 12 Table 13 Table 14 Table 15 Table 16 Table 17 Table 18
TW total annual contaminant release for Bordon STW Releases to Air, 53 TW total annual contaminant release for Bordon STW Releases to Water, 54 Total daily and annual abstraction quantities from private licensed supplies, 59 Dry Weather Flow and Maximum Daily Flow Quantities for all Discharge Consents, 59 South East England Seasonal Mean Temperature and Precipitation Change (at 50th Percentile) by 2050, 64 Water Demand Modelling Parameters (Halcrow vs PBA), 70 Model run schedule, 74 Outline estimate of surface water storage volume and indicative land take for each drainage catchment, 86 Water scenarios at different scales and illustrating increasing degree of ‘risk’, 95 Water Options, 100 Indicative costs estimate for Sustainable Drainage Measures, 113 Hierarchical approach towards SuDS Measures, 114 Indicative supply infrastructure costs, 117 Indicative treatment infrastructure costs, 118 Potential Water/ Wastewater Suppliers for Whitehill Bordon, 120 Water Supply Methods and Water Neutrality, 130 Required Studies, 132
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Executive Summary
One of the core themes of the WCS is that of community participation and ownership, which is reflected in the inclusion of the settlements of Headley Down and Headley within the development and retrofit proposals.
The WCS aims to identify the water supply and demand for the proposed eco-town and determine whether there are sufficient water resources and infrastructure in the locality to sustain the population.
The other key driver for the proposals is the requirement specified in supplementary planning guidance for ecotowns that supports Planning Policy Statement 1 (PPS 1) Planning and Climate Change, which requires eco-towns to achieve water neutrality. The WCS sets out a number of innovative water management measures which can enable the eco-town to not only achieve water neutrality, but also serve as a best practice example of water management that can be replicated in other settlements and large-scale developments across the UK.
The WCS has also highlighted the appropriateness of water management measures and approaches in the context of the Water Framework Directive (WFD), focussing in particular on the benefits and drawbacks of certain solutions in relation to the impact on habitats, water quality, the local community, protected sites and other sensitive receptors. To achieve compliance under the WFD, it is important that where practicable the eco-town works
Scope and Background The eco-town provides the opportunity to produce and test innovative means of water resource management and provides the platform to develop long-term partnerships with stakeholders, local authorities, developers and utility providers to create a world leading sustainable settlement. This detailed Water Cycle Study (WCS) has been prepared by Peter Brett Associates LLP to support the potential development of the proposed eco-town at the Ministry of Defence (MoD) garrison at Whitehill Bordon. The detailed WCS builds upon the Outline WCS prepared by Halcrow in 2009, and has been prepared in accordance with national, regional and local planning guidance, as well as the aspirations of the Whitehill Bordon Eco-town Executive Group and Delivery Board. The WCS provides supporting evidence for EHDC’s emerging Core Strategy and summarises the consultation, investigation, analysis and results from the WCS and has been prepared in consultation with the Environment Agency (EA), East Hampshire District Council (EHDC), Hampshire County Council (HCC) and the local stakeholders of Whitehill Bordon. Some of the principles of the WCS are outlined in the following section:
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towards achieving good chemical and ecological status in affected water resources.
Consultations As part of the study the following stakeholders have been consulted regarding policy, legislation and aspirations for water cycle management, habitats and ecology:
Environment Agency; Hampshire County Council; East Hampshire District Council; Whitehill Town Council (WTC)
South East Water (SEW); Thames Water (TW); Kelda Water Services
Ministry of Defence (MoD); Natural England (NE); National Trust (NT); Hampshire and Isle of Wight Wildlife Trust (HIoW); Deadwater Valley Trust; English Heritage (EH)
Water Supply The detailed WCS has identified that there are sufficient water resources in the locality of the eco-town which can sustain the increased development by utilising an innovative and sustainable water management system providing both potable and non-potable water supplies to achieve a ‘water neutral’ status. Without such an approach the total water demand would have to be sustained by increasing the current yields of
groundwater from either the SEW or MoD boreholes, which could have detrimental impacts on nearby European Designated Sites that rely upon the prevailing hydrogeological conditions (and may also not achieve compliance under the Water Framework Directive and Habitats Directive) and reduce the likelihood of enabling the eco-town to achieve a ‘water neutral’ status. As part of the Habitats Regulations Assessment it was determined that the eco-town development was not likely to have a significant effect on the local hydrological and hydrogeological regime. However, there is still a need to ensure that ongoing monitoring is provided to guard against any potential impacts in the future. For the eco-town to be sustainable, achieve water neutrality and ensure there is nildetriment to adjacent sensitive European Designated Sites (and other protected areas) requires maintenance and utilisation of the current MoD groundwater abstraction, which can be used to sustain the potable water demand, whilst implementation of a sustainable and innovative green water supply, treatment and distribution system which can be used to provide for nonpotable water uses. Water demand modelling has demonstrated that ~37% of the total water demand can be sustained by ‘green water’ (nonpotable water resource) through collection and treatment of waste water for reuse in the eco-town.
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Water Management Measures The eco-town provides the platform for testing and installation of new water efficiency and management measures. As the development is located within the River Wey Catchment which is classified as ‘No Water Available’ according to the EA Catchment Abstraction Management Study, the success of any water management system will be reliant (in part) on incorporation of water efficiency measures not only at a sitewide scale, but also on a plot scale. The following options have been considered as part of this study:
Fitting of new build and of existing housing stock with water efficiency devices and water meters.
Connection of new and existing properties to the green water distribution network to ensure continuity of potable and non-potable water supply.
Installation of a new site waste water treatment facility, either as a standalone facility or in tandem with the existing Bordon treatment works, which can incorporate both black water, rainwater and grey water treatment.
Connection of the surface water drainage system with a rainwater collection system to supplement the green water supply.
Rolling out innovative water metering programmes across the eco-town.
Creation of an inset water management company (e.g. Town Water Company) to oversee the ownership, operation and maintenance of water services.
Encouraging behavioural change with respect to water consumption and management, through offering accurate information and choices.
The study has also recommended a framework plan for tackling the issue of public perception of water supply, management and demand, which focuses on encouraging behavioural change through sharing and dissemination of information, utilising social media and encouraging partnerships and collaborative working to spread the water efficiency message.
Conclusion The detailed WCS has demonstrated that a robust water management strategy can be implemented on site, which meets local and national best practice guidance and legislation on water management. Through careful design and incorporation of innovative water management techniques the water demand for the eco-town can be sustained whilst also achieving water neutrality. It has been considered that the recycling and treatment of waste water within the development can enable current rates of groundwater abstraction (used for
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potable water supply) to remain at existing levels, which should have nil-detriment on the local hydrogeological regime. However, further investigations are recommended to confirm this rationale, which include:
Map 1: Policy Boundaries, Protected Areas & Zone of Influence for Water Neutrality
Long-term hydrogeological monitoring to ascertain the current groundwater regime, interactions with designated sites and influence of the eco-town proposals
Ground investigations to inform the design and management of new surface water drainage systems
Hydraulic modelling of the Oxney Drain to determine the existing flood risk constraints and options for management/ restoration
Pursuing the feasibility of an Inset Water Management Agreement to enable wholesale management of all water resources across the eco-town as well as assessing the biological capacity of the Oxney Drain to receive flows from a new treatment works
Investigation into source of and solutions to the occasional bacteriological contamination at the MoD Borehole
Site-wide investigation into areas of the MoD surface water and foul water drainage network to eliminate any crossconnections.
These investigations will enable the delivery of a sustainable and robust development. The recommended water resource solutions and associated infrastructure costs are outlined in the following tables. The options consider, water supply, water treatment, flooding, drainage, ownership and maintenance. Section 11 of the WCS provides more detail on the recommendations, costs and feasibility of implementation for each of these items. Map 1 (opposite) shows the location of the eco-town and policy areas.
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Component Surface Water Drainage
Approach SuDS (e.g. swales, permeable paving, attenuation basins) used wherever possible to control quality and quantity of surface water runoff.
Opportunities Most sustainable solution Improved quality of life.
Constraints Difficulties in adoption and maintenance.
Enhanced natural environment.
May require management company.
Existing surface water drainage retained and combined with sustainable drainage measures where possible – requires site investigations to confirm.
Working with natural processes.
Drainage strategy must tie in with Green Infrastructure Strategy.
Flood Risk
Areas of the site with a significant risk of flooding used for ‘water compatible’ development only (in accordance with PPS25). Eco-town will not have a detrimental impact on flood risk, and where possible will aim to reduce flood risk The total discharge and volume of surface water leaving the eco-town will be lower than the existing discharge rate for the development within the eco-town boundary.
Could be owned and operated by inset water management company.
Indicative Costs/ Implications £1.5m for conventional drainage network (Turner & Townsend Infrastructure costs Report)
SuDS require more land-take – loss of developable area.
Requires Environment Agency approval.
Opportunity for innovative link-up with water supply system (e.g. rainwater collection and redistribution as non-potable water resource). Most sustainable method of development allocation. Ensures long-term viability of development and reduces/ eliminates flood damage costs.
£1.3m for attenuation measures (e.g. swales, basins)
Strict design criteria.
No built development within the floodplain reduces the total developable area.
Any infrastructure costs associated with the restoration of the Oxney Drain will be defined following the completion of a hydraulic modelling study and an agreed approach with the EA.
Eco-town can have a beneficial impact elsewhere in the catchment by reducing downstream flood risk.
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Component
Approach
Opportunities Opportunities
Constraints
Water Supply
Development requires potable water supply, either taken from MoD supply borehole, or, a direct supply from the SEW potable water distribution network.
MoD Borehole Supply: Supply Continuation of supply within limits of the current abstraction would have greatest benefits for hydrogeological regime, ecology and habitats. - More favourable in terms of compliance with Habitats Directive and Water Framework Directive. - Ties in with eco-town criteria to use and develop innovative water management solutions. - Would eliminate cost of any infrastructure associated with treatment, collection and supply of green water.
MoD Borehole Supply: Supply - Further detailed hydrogeological study is required to confirm the interconnectivity and water resources shared between the town and the surrounding designated sites.
Town requires green water recycling solution to satisfy the water demand and achieve Water Neutrality.
Water Treatment
Sewage either pumped out towards Bordon Sewage Treatment Works, a new works at site of the MoD pumping station or a combination of the two, with the new works being brought online after the initial development phases.
New Works: - Local stakeholders more supportive of new works within ecotown boundary. - If Green water recycling and treatment is sought then centralised waste water works may be preferable than two separate works. - Green water facility would assist in meeting the eco-town’s goal of water neutrality.
South outh East Water Supply: - Would require a greater volume of potable water and increased groundwater abstractions from the existing South East Water supply boreholes. - Least favourable in terms of compliance with the Habitats Directive and Water Framework Directive. - EA unlikely to grant any increase in groundwater abstraction - River Wey Catchment is classified as ‘No Water Available’ according to the CAMS. Bordon Works: Works - Lacks capacity to receive any further foul effluent. Requires significant capacity upgrades.
Indicative Costs/ Implications Potable Water Distribution Main: Main £3m (Turner and Townsend Estimate) Grey Water Collection Main: £1.35m (Turner and Townsend Estimate) Black Water Collection Main: £3.05m (Turner and Townsend Estimate) Green Water Distribution Main: £3m (derived from Turner and Townsend Estimate)
Foul and Green Water Treatment Facility: Facility £3m£4.5m
New Works: - Unlikely that incumbent water companies would take on ownership and maintenance of green water treatment facility. - Biological capacity of Oxney Drain (receiving system for treated effluent) would need to be assessed to inform the discharge consent.
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Component
Approach
Opportunities
Constraints
Ownership & Maintenance
Merging water services under one provider would make water management more sustainable.
Customer base provided with one bill
One possible approach (and one which is preferred by local stakeholders) is to establish a ‘Town Water Company’ within the eco-town boundary, which could either be an inset commitment owned and managed by the town, or at least by its operating agent, and which would probably draw on the existing infrastructure of the current incumbents.
Overcomes issues of maintenance and adoption arrangement between local authority and water companies.
The implications are wide ranging and especially in times of financial constraint on the Local Authority, this solution may not be generally acceptable.
Fits in with eco-town core theme of finding innovative and sustainable solutions
It would require a team skilled in the operation of such a customer base. Highly unlikely that incumbent water companies will agree to the provision of ‘green water’.
Provides more scope for testing new solutions
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Indicative Costs/ Implications Costs are impossible to determine at this stage of the eco-town proposals. It only makes sense to include costs if a water resources strategy has been agreed by all parties.
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1 Background 1.1 Purpose Peter Brett Associates LLP (PBA) was commissioned by East Hampshire District Council (EHDC) on behalf of the Whitehill Bordon Opportunity Team to complete a detailed Water Cycle Study (WCS) in support of the proposals for the Whitehill Bordon Eco-town. The Outline WCS was completed to support the draft masterplan during the preferred options stage of the Core Strategy and also provided the template for the detailed WCS. The WCS will feed directly into the evidence base to support the emerging Core Strategy for EHDC. The detailed WCS has been completed in line with the most up-to-date WCS guidance from the EA and CIRIA document C960. A flow diagram outlining the Water Cycle Study process as detailed in the CIRIA C690 is included in Figure 1. One of the principle aims of the WCS is to generate draft policy and guidance for authorities, businesses and developers, which collectively can help to achieve the aim of water neutrality for the eco-town proposals. The EA (2009) define water neutrality as follows: “For every new development, total water use across the wider area after the development must be equal to or less than total water use across the wider area before the development”.
Figure 1
Different stages of a water cycle study (Source: CIRIA C690)
The CIRIA document C690 ‘Guidance on Water Cycle Management for New Developments (WaND)’ (2010) provides
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specific guidance for the content and coverage of a Detailed WCS. CIRIA C690 recommends that the Detailed WCS should:
Identify what water cycle infrastructure is required and where it is needed
Identify who is responsible for providing the infrastructure and by when it has to be provided
Provide guidance for local authorities and developers on site specific infrastructure requirements.
Of critical importance to the completion of the WCS and achieving wider sustainability objectives, is the concept of water neutrality. The concept of water neutrality is described in Planning Policy Statement 1 (PPS1) (Eco-town supplement). This document requires eco-towns in areas of serious water stress to aspire to water neutrality, which translates into achieving development without increasing the overall water consumption across a ‘wider area’. The PPS1 supplement states that the WCS should: a) assess the impact that the proposed development will have on water demand within the framework of the water companies’ water resource management plans and set out the proposed measures which will limit additional water demand from both new housing and new non-domestic buildings;
b) demonstrate that the development will not result in a deterioration in the status of any surface waters or groundwaters affected by the eco-town, and; c) set out proposed measures for improving water quality and avoiding surface water flooding from surface water, groundwater and local watercourse. The WCS considers these requirements through consultation with local stakeholders, authorities and water companies; technical assessment of water resources, current and future demand and potential environmental impacts, and formulation of appropriate water management policies and relevant developer guidance. The principle to be adopted in working towards a reduction of demand on limited water resources can be illustrated in the following diagram (Figure 2). This shows how the planning and design of a new community needs to have the water cycle in mind and how the demands on resources should be considered at the appropriate stage and its integration with energy demand and green infrastructure. This does not suggest that all elements have to be implemented but merely that they need to be considered and the effectiveness in any particular scheme maximised within the constraints which will be unique to the locality.
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1.2 EcoEco-town
targets in reducing energy use, water consumption and carbon emissions.
Planning Background In 2010 the Government shortlisted Whitehill Bordon, along with three other sites, as potential locations for the creation of new settlements of between 5,000 to 20,000 homes designed to achieve zero carbon and sustainable living and working environments.
1.2.1
Proposals Whitehill Bordon is located in East Hampshire and is within the vicinity of the newly designated South Downs National Park. The proposals at Whitehill Bordon are being led by EHDC as part of a broad partnership including Whitehill Town Council (WTC), Hampshire County Council (HCC), Ministry of Defence (MoD), Natural England (NE) and the Homes and Communities Agency (HCA). Currently, the scheme is awaiting the decision of the occupier (the MoD) to confirm potential dates for the relocation of their training operations elsewhere in the UK. 1.2.2
It is the intention that the proposed development will create a new ‘district’ town with a population estimate of 30,000 inhabitants and up to 5,300 new homes, in addition to commercial, educational and industrial opportunities. The scheme also provides for undertaking a programme of retrofitting of existing properties with energy, carbon and water efficient technologies, which is aimed at achieving sustainability
Figure 2
Water Hierarchy in Development
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For the purposes of this study the land which falls within the boundary of the eco-town has been classified into eight separate zones to aid in the description of the baseline conditions, issues and proposed water management measures. These zones have been delineated based upon general topography, main roads and watercourses which all act as definable boundaries within the context of the evolution of the masterplan. Figure 3 illustrates that delineation of these zones. 1.2.3 Supply and Demand Issues The South East Water (SEW), Water Resource Management Plan (SEW, 2008) reports that there is sufficient headroom within the Resource Management Zone (RMZ 5) to sustain current and projected demand up to 2035. The demand projections take into account the potential impacts of climate change and a forecasted increase in demand from 151 litres per head per day to 166 litres per head per day for metered users. Further consultation with SEW has confirmed that the demand projections are based on forecasted increases in water consumption from the development of the eco-town. EcoEco-town Boundary Figure 3
Water Management Zones within the eco-town Boundary Contains OS Data (Crown Copyright 2011)
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Based on an average consumption for the South East of England of 160 litres per person per day and the expected increase in population of 11,925 people as a result of the ecotown (5,300 dwellings multiplied by occupancy rate of 2.25), the anticipated water demand will be ~2 Ml/d. SEW’s plan (SEW, 2008) also reports that the two local SEW supply boreholes (which supply Whitehill Bordon and other settlements in the wider area) have a combined dry year deployable output of approximately 14 Ml/d. Although there is sufficient headroom (in that the boreholes are not operating at full capacity) the boreholes are only licensed to abstract 14.1 Ml/day, leaving little headroom for the additional demand. Therefore, unless there are changes to the EA abstraction licenses (which will be difficult to achieve given the local groundwater fed European Designated Sites and the River Wey Catchment status as ‘No Water Available�) the SEW boreholes will not be able to meet the demand of the eco-town. Currently, the MoD barracks are sustained by a private groundwater abstraction taking between 0.6 and 1.5 Ml/d (Enviros, 2003). If this source could be used to continue to supply the existing housing stock at the MoD site as well as the new built development, then the water demand of the eco-town may be achieved (in part). However, it is unlikely that continuation of this supply in isolation can sustain the entire eco-town. Therefore, to tackle this water deficit, a suite of water efficiency and innovative
water recycling measures may have to be incorporated into the proposals to reduce water demand and ensure there is no detrimental impact on the groundwater resource, existing population and surrounding habitats (i.e. Water Neutral). Furthermore, the opportunity to implement efficient use of water in the eco-town development will also make resources available for use elsewhere.
1.3 Scope of Study The WCS provides an overview of current and existing water resource pressures in the Whitehill Bordon locality and wider area, as well as identification of workable engineering solutions, consideration of various development scenarios and potential delivery mechanisms. Accordingly, the WCS:
Generates draft Whitehill Bordon core strategy policies on water neutrality
Identifies major infrastructure requirements, including indicative costs, timing, delivery mechanisms and phasing
Outlines guidance for developers to support all sustainable water management options and progress towards the water neutrality target
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Indicates further studies required to support the planning process and to refine the solutions identified
Builds upon the findings from East Hampshire District Council's Strategic Flood Risk Assessment to reflect the proposals at Whitehill Bordon
Provides input into and consideration of the Habitats Regulations
Includes information and guidance from the Whitehill Bordon Green Infrastructure Strategy and Local Biodiversity Action Plan
Feeds through information into the energy feasibility study.
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2 Outline Water Cycle Study 2.2.1
Water Abstraction and Demand Management
2.1 Scope of Study
The Outline WCS provides a good starting point in terms of identifying the opportunities, constraints and potential options to reduce the impacts of the eco-town on surrounding environments, habitats and water resources.
Reduce water demand (and hence abstraction requirements to less than 0.8Ml/d) combined with the use of the potential source of the MoD groundwater abstractions, the SEW source or a combination of the two
The MoD source needs to be investigated further to assess its current impact and any future impact on nearby European designated sites as result of closure or use as part of the eco-town water cycle.
The study also identified that there were no major issues concerning resources, environmental constraints or existing development which would prevent the eco-town proposals being progressed. Furthermore, the Outline WCS reports that the South East Water (SEW) Water Resource Management Plan (SEW, 2008) confirms that there is sufficient water available within their Water Resource Management Zone to support future development at Whitehill Bordon.
2.2 Recommendations Along with the principal recommendation of the Outline WCS that a detailed WCS should be undertaken to develop long term value for money water cycle solutions, the recommendations summarised in the following section were also made in relation to future development and further investigation.
2.2.2
Water Recycling Reduction
Collection and minor treatment (filtration and disinfection) of light grey water for toilet flushing.
Dark grey water and foul effluent collected from houses and sent to treatment works.
Potentially for industrial effluent and/ or grey water recycle and reuse within factories or production facilities.
With the water efficiency measures in place, the Outline WCS recommended the typical reduction in household consumption would be between 30-40% (reducing household consumption from 160l/h/d to 100l/h/d. Through the use of variable tariff metering, this is anticipated to be 80l/h/d.
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2.2.3
Water Treatment and Distribution
Further investigation into the existing water treatment works would be required to assess its suitability for reuse or upgrade.
Based on Halcrow’s assessment, the adopted strategy of reducing total water demand negates the need for any major works to upgrade existing water treatment facilities.
An efficiency audit of the existing water treatment works is required to assess any opportunities for power, water or chemical savings.
2.2.4
Flood Risk and SuDS SuDS
The concrete ditch should be transformed into a more natural watercourse, including removal of culverts and realignment to reduce flood risk to parts of the site.
The study recommends 15% of the development areas are reserved for wetlands, swales, ponds and infiltration basins.
2.2.5
Wastewater Treatment
The study recommends that the eco-town should make a contribution to improved river quality (e.g. lowering Phosphorous levels in rivers). The Outline WCS recommends that the effluent from waste water treatment works (i.e. Bordon or a new works) aims for a target phosphorous concentration of 20Âľg/l. This is based on the
WFD phosphorous targets to achieve high quality status for watercourses.
2.3 Moving Forward A review of the Outline WCS was completed to identify areas requiring further investigation, as well as aspects of the study which could be improved and covered within the detailed WCS. However, it must be recognised that the aim of the Outline WCS was to provide only a broad scale assessment of water resource and management issues to support the development of the draft masterplan as part of the preferred options stage of the core strategy. The Outline WCS provides a good platform to move forward with the eco-town proposals and the concepts presented in the study align with national legislation, best practice and guidance on water cycle management. Furthermore, the study also provided a framework to enable the completion of the detailed WCS.
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3 Legislation & Policy The development opportunities and engineering solutions that are required must comply with legislation, policy and guidance at the national, regional and local level. Ultimately there is a compendium of authorities and organizations with an interest in the proposals and before development options can be approved, they must first be shown to be compliant with relevant legislation. As part of this process, PBA has undertaken a comprehensive review of all relevant legislation that is directly applicable to the eco-town proposals, in the context of water management. This considers national planning policy, environmental directives, regional plans and strategies, environmental studies and local policy.
flooding and to direct development away from areas at highest risk. PPS25 contains a risk based approach to the planning process and requires that the sequential test is used to guide the decision making process by steering development to the lowest probability flood zones where feasible. PPS25 defines three Flood Zones to be used as the basis for applying the sequential test and introduces the Flood Risk Vulnerability Classification which defines the type of development that is considered appropriate within each Flood Zone. Taken together, the Flood Zones and Flood Risk Vulnerability Classification are used to provide a Flood Zone “Compatibility� matrix.
3.1 European and National Legislation, Policy and Guidance
In addition to providing guidance in respect of flooding associated with rivers and tidal sources, PPS25 sets out guidance for managing surface water run-off from development. Specifically, the guidance requires that through the use of Sustainable Drainage Systems (SuDS) the developed rate of run-off into a watercourse or other receiving system should be no greater than the existing rate of run-off. In addition, developers are encouraged to reduce volumes of runoff using infiltration techniques.
Planning Policy Statement 25 25 – Development and Flood Risk (Updated March 2010) PPS25 focuses on national policy and seeks to provide clarity on what is required at regional and local levels to ensure that flood risk is taken into account at all stages in the planning process to avoid inappropriate development in areas at risk of
The PPS25 Flood Zones do not currently take account of climate change impacts. However, PPS25 requires that the spatial planning process should consider such issues and contingency allowances are provided to enable the implications of climate change to be considered over the lifetime of the development.
3.1.1
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Planning Planning Policy Statement 1 – Delivering Sustainable Development (2005) The Sustainable Communities Plan was published by the previous Government in February 2003 and established the key planning policy context for regeneration. The aspirations of the Communities Plan were reinforced by policy guidance including that in PPS 1: Delivering Sustainable Development, published in January 2005. The Statement sets out the overarching planning policies on the delivery of sustainable development through the planning system. Paragraph 5 of PPS1 sets out the framework for sustainable planning which should: 3.1.2
Make suitable land available for development in line with economic, social and environmental objectives to improve people's quality of life
Contribute to sustainable economic development
Protect and enhance the natural and historic environment, the quality and character of the countryside, and existing communities
Ensure that development supports existing communities and contributes to the creation of safe, sustainable, liveable and mixed communities with good access to jobs and key services for all members of the community.
3.1.3
Supplement to PPS1 (Planning and Climate Change) (2007)
Sets out how planning, in providing for the new homes, jobs and infrastructure needed by communities, should help shape places with lower carbon emissions and resilient to the climate change now accepted as inevitable. 3.1.4
Planning Policy Statement: ecoeco-towns - A supplement to Planning Policy Statement 1 (2009)
This PPS sets out the standards that an eco-town has to adhere to and outlines the various locations that have been identified as having the potential to become an eco-town. The document provides a set of minimum standards for eco-towns which are deliberately designed to go beyond standard developer guidance with the aim of establishing eco-towns as exemplars of good practice. Moreover, the document makes clear that eco-towns should “take full account of the impact on local ecosystems, mitigating negative impacts as far as possible“. Of particular relevance is policy ET 17 Water. The policy breakdown is as follows:
ET 17.1 Eco-towns should be ambitious in terms of water efficiency across the whole development, particularly in areas of serious water stress20, and should contribute, where existing water quality leaves scope for further improvement, towards improving water quality in their localities.
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ET 17.2 Planning applications for all eco-towns should be accompanied by a water cycle strategy that provides a plan for the necessary water services infrastructure improvements. The water cycle strategy should have been developed in partnership with interested parties, including the local planning authority, the Environment Agency21, and the relevant water and sewerage companies through a water cycle study. The strategy should: a) assess the impact that the proposed development will have on water demand within the framework of the water companies’ water resource management plans and set out the proposed measures which will limit additional water demand from both new housing and new non-domestic buildings b) demonstrate that the development will not result in a deterioration in the status22 of any surface waters or ground-waters affected by the eco-town c) set out proposed measures for improving water quality and avoiding surface water flooding from surface water, groundwater and local watercourses. ET 17.3 Eco-towns should: a) incorporate measures in the water cycle strategy for improving water quality and managing surface water, groundwater and local watercourses to prevent surface water flooding from those sources; and b) incorporate sustainable drainage systems (SuDS) and, except where this is not feasible, as identified within a
relevant Surface Water Management Plan avoid connection of surface water run-off into sewers.
ET 17.4 Planning applications for all eco-towns should include a strategy for the long term maintenance, management and adoption of the SuDS.
ET 17.5 Eco-towns in areas of serious water stress should aspire to water neutrality, i.e. achieving development without increasing overall water use across a wider area and this is further explained in Annex B of this PPS. In particular, the water cycle strategy should set out how: a) the development would be designed and delivered to limit the impact of the new development on water use, and any plans for additional measures, e.g. within the existing building stock of the wider designated area, that would contribute towards water neutrality b) new homes will be equipped to meet the water consumption requirement of Level 5 of the Code for Sustainable Homes; and c) new non-domestic buildings will be equipped to meet similar high standards of water efficiency with respect to their domestic water use.
3.1.5 Habitats Directive (92/443/EEC) (Updated 2010) The Habitats Directive was adopted in 1992 and sets out the framework by which the European Union achieves its obligations under the Bern Convention. The principal aim of the Directive is to promote the maintenance of biodiversity by
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placing the responsibility on EU states to maintain or restore habitats and protected species and protect European designated sites. The key aspects of the Directive which are relevant to the WCS are as follows:
Maintain or restore protected habitats and species to a favourable conservation status
Put conservation measures in place to manage SACs and ensure that development, plans and projects that may have a significant effect on the protected sites conduct an appropriate level of assessment. If there are no alternatives for development, and there are other reasons within the public interest (e.g. economic objectives) then detrimental development may take place. However, compensatory measures are necessary to ensure the overall coherence of the Natura 2000 network.
The Conservation of Habitats and Species Regulations transposed the Habitats Directive into national law. The Regulations came into force on 30 October 1994 (updated on 1 April 2010), and apply to land and territorial waters out to 12 nautical miles from the coast. Water Framework Directive Directive (2000/60/EC) (2000) The Water Framework Directive (WFD) is a wide-ranging piece of European legislation that establishes a new legal framework for the protection, improvement and sustainable use of surface
3.1.6
waters, coastal waters and groundwater across Europe in order to:
Prevent deterioration and enhance status of aquatic ecosystems, including groundwater
Promote sustainable water use
Reduce pollution and
Contribute to the mitigation of floods and droughts
Water management has historically been co-ordinated according to administrative or political boundaries. The WFD promotes a new approach based upon management by river basin – the natural geographical and hydrological unit. The Thames River Basin Management Plans include clear objectives to achieve good water quality through reductions in demand and pollution control and a detailed account of how objectives are to be met within a prescribed timeframe. This is covered in more detail in Section 3.2.1. 3.1.7
Wildlife and Countryside Act (1981)
The Act tackles the problem of species protection and loss of habitat. The Act identifies Sites of Specific Scientific Interest (SSSIs) as being critical to this process. SSSIs are notified under Section 28 of the Act. Notification is essentially a statement of scientific value, which does not include any prohibitive powers
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and depends upon landowners or users to inform of any activities which are likely to damage the site. SSSIs can be features of interest in earth science including rock types, crustal structures, landforms and erosion products, while in ecology the features can be defined as species or life forms, habitats and ecosystems. 3.1.8 Flood Risk Regulations (2009) The Flood Risk Regulations transpose the Floods Directive 2007/60/EC into domestic law. The Regulations require that the Environment Agency enables the preparation of flood maps and Preliminary Flood Risk Assessments (PFRAs) by Lead Local Flood Authorities (Unitary and County Councils) for flooding from seas, main rivers, reservoirs and all other sources of flood risk, except sewer flooding not caused as a result of rainfall. Defra and Communities and Local Government have published Surface Water Management Plan (SWMP) Technical Guidance to assist lead local flood authorities. SWMPs consider the management of surface water within a given authority, and aim to deliver water resources, flood risk and water quality benefits through a coordinated approach between local stakeholders and focussed investment. PFRAs must be prepared before the end of 2011. Maps of Significant Areas of Flood Risk, determined by the aforementioned PFRAs, must be prepared by the end of 2013. Flood Risk Management Plans are to be prepared before the end of 2015.
3.1.9 Flood and Water Management Act (2010) The Flood and Water Management Act takes forward some of the proposals in three previous strategy documents published by the UK Government - Future Water, Making Space for Water and the UK Government’s response to the Sir Michael Pitt’s Review of the Summer 2007 floods. In doing so it gives the Environment Agency a strategic overview of flood risk, and local authorities responsibility for preparing and putting in place strategies for managing flood risk from groundwater, surface water and ordinary watercourses in their areas. Further statutory instruments standards and guidelines, which will determine the full extent of the Act, are yet to be published. Water Resources Act (1991) The Water Resources Act 1991 (WRA) came into effect in 1991 and replaced the corresponding sections of the Water Act 1989.
3.1.10
The WRA sets out the responsibilities of the Environment Agency in relation to water pollution, resource management, flood defence, fisheries, and in some areas, navigation. The WRA regulates discharges to controlled waters, namely rivers, estuaries, coastal waters, lakes and groundwater. Discharge to controlled waters is only permitted with the consent of the Environment Agency. Similarly, a licence is required to abstract from controlled waters.
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3.1.11 Water Industry Act (1991) The Water Industry Act 1991 established the Office of the Water Regulator (OFWAT) which has the responsibility for licensing water suppliers and sewerage undertakers. This resulted in the privatised water industry and set standards for performance of the water companies for supply of “wholesome” water and treatment of sewage. OFWAT has the remit for control of pricing and investment in water supply and sewerage systems to meet environmental standards and social obligations. The industry is regulated on a 5 year asset management plan (AMP) investment cycle and is currently (2011) in the period AMP5, which runs through to 2015. The investment plans and consequent water charges are measured against need to meet certain defined obligations such as leakage control, flooding, water quality and resources. OFWAT regulates the plans to establish efficiencies and control prices to maintain competitiveness. Investment in addition to the AMP programme has to be funded separately (by other financial contribution) or delayed to the next AMP period. The Act does allow for the establishment of new water supply and/or sewerage companies to be established to serve a particular, defined area. These are called Inset Appointments and are also regulated by OFWAT. Such an appointment has to
be approved by the incumbent water and/or sewerage company. 3.1.12 Land Drainage Act (1994) There have been various updates to the Land Drainage Act, but essentially the Act consolidates the enactments relating to internal drainage boards, and to the functions of such boards and of local authorities in relation to land drainage. The Land Drainage Act sets out the responsibilities of various authorities and stakeholders in relation to the management, maintenance and ownership of watercourses, and allows those stakeholders responsible to produce their own land drainage byelaws. Water Supply (Water Fittings) Regulations (1999) These replaced all water bye laws put in place by each of the water supply companies and provide a national common standard. They also enabled a standardisation of fittings and application across the European Economic Area. 3.1.13
They require types of fittings and standards of connection to prevent contamination of wholesome water 3.1.14
Drinking Water Regulations 2000 and 2007 [Water Supply (Water Quality) Regulations] (2000)
Set out the standards and procedures for meeting the Drinking Water Directive (DWD) for the provision of “wholesome” water.
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Building Regulations Part G (2010) The most relevant change to the most recent version of the Building Regulations stipulates the requirement for a “wholesome” water supply to key appliances in the home, notably excluding the toilets and washing machines. Part 7 of the Building Regulations 2010 sets out maximum rates of potable water consumption for new dwellings, stating that: 3.1.15
Sewers for Adoption 6th Edition (2006) Sewers for Adoption is the standard in England and Wales for the design and construction of sewers to adoptable standards. It is a guide to assist developers in preparing their submission to a Sewerage Undertaker prior to entering an Adoption Agreement under Section 104 of the Water Industry Act 1991. 3.1.17
3.1.18 “The potential consumption of wholesome water by persons occupying a dwelling to which this regulation applies must not exceed 125 litres per person per day…” Wholesome (or potable) water is defined as “water which would be regarded as wholesome for the purposes of regulations made under section 67 of the Water Industry Act 1991…”. The Drinking Water Inspectorate define the standards for wholesome (potable) water. 3.1.16
Interim Code of Practice for Sustainable Drainage Systems (2004)
This Code of Practice provides support for developers in promoting and implementing a sustainable approach to water management and in particular Sustainable Drainage Systems (SuDS), to ensure their long-term viability and to promote consistent use. The document sets out the key regulatory requirements that must be considered and adhered to before SuDS are installed and commissioned.
Water Resources Planning Guideline, EA (November 2008)
This guideline document provides guidance for water companies on the EA’s preferred approach to adopt in the development of water resource plans, to ensure that their plans meet the requirements of the Water Industry Act 1991. The guidance encourages water companies to utilise sustainable and environmentally sound principles in their future management strategies, incorporating allowances for climate change and outlining the impacts of proposed options on water supply and the environment. 3.1.19
Water Resources Resources in England and Wales – Current State and Future Pressure, EA (December 2008)
This EA document provides a summary of the present and potential stresses relating to water resources in England and Wales. The document recognises that changing environments and climates are reducing available water supplies, with the greatest pressures being felt in the South East and Eastern England owing to the high population densities, large-scale irrigation practices and dry climate.
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3.1.21 The document identifies those areas failing from pollution and abstraction pressure, and classifies a number of sites as Restoring Sustainable Abstraction (RSA) sites. The document is particularly relevant to wetland habitat and designated sites in the vicinity of Whitehill Bordon, as it encourages rural communities to make space for water and highlights the benefits that wetland habitats can bring in terms of protection of heritage, adaptation to climate change and moderation of climatic extremes (e.g. floods and drought). 3.1.20
Benefits of Green Green Infrastructure Report, Forest Research (October 2010)
This report by Forest Research provides generic explanations of the various benefits of green infrastructure along with lists and references to relevant case studies and reports. Green infrastructure can help to reduce ambient heat and flooding in urban areas, as well as removal of CO2, increased biodiversity and sustainable transport linkages. The effective design of green infrastructure is critical to many aspects of the development, as many of the proposed green corridors will also serve a multiple purpose for surface water attenuation, wildlife movement and public transit.
Sustainability Appraisal and Habitats Regulations Assessment of the Draft EcoEco-towns PPS and the EcoEcotowns Programme (2009)
This document provides a description of the appraisal of the eco-towns programme in the context of sustainability and habitat regulations. The document concludes that the requirement of the PPS1 eco-town’s supplement to undertake a Water Cycle Strategy is an improvement on business as usual. Likewise, the requirement to achieve water neutrality also represents an improvement on current planning requirements. The appraisal recommends that any new development should only take place when sufficient waste water treatment capacity is in place (i.e. water treatment infrastructure capable of supporting the entirety of any future development has to be constructed first). In the case of Whitehill Bordon, if sufficient infrastructure is not put in place before construction, then this could result in development stagnation, limited by existing constraints in the already over-stretched sewerage infrastructure. Specifically, the document identifies the need to enlarge Bordon sewage treatment works.
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3.2 Regional Policy and Guidance 3.2.1
Thames River Basin Management Plan, EA (Thames Region) (December 2009)
The River Basin Management Plan focuses on achieving protection, improvement and sustainable use of water and is a requirement of the Water Framework Directive (WFD). The plan identifies the management of future development as one of the key aspects which can influence achievement of the WFD requirements:
The document identified that historic urban development as being responsible for some of the negative issues faced within the region. The document mentions the proposed development of eco-towns within the river basin district and places particular emphasis on ensuring that WCSs consider the requirements for adequate infrastructure, water efficiency measures and dual function green corridors to prevent any further deterioration, and potentially improve levels of water quality, availability and flood risk. The document identifies growth points such as Whitehill Bordon as providing the potential to work with local authorities, water companies and other partners to ensure
Water Cycle Studies are being completed correctly and are reported in local and regional plans. 3.2.2
South East Plan Policy CC8: Green Infrastructure (2009)
Policy CC8 outlines a series of measures and targets for local authorities and partners to set aside and plan dual function greenspace. The policy states that green infrastructure should:
Include both existing and new green infrastructure;
Deliver the widest range of linked environmental and social benefits including conserving and enhancing biodiversity as well as landscape, recreation, water management, social and cultural benefits to underpin individual and community health and ‘well being’, and;
Boost the sustainable development of settlements and increase the environmental capacity of the locality and region as a whole, helping communities to be more resilient to the effects of climate change.
3.2.3
Wey Catchment Abstraction Management Strategy (CAMS), EA (March 2008)
The Wey CAMS has been reviewed as part of the WCS. The Wey catchment itself contains a number of internationally and nationally important designated sites that are groundwater-fed. This includes lowland wet heathlands, a rare habitat both nationally and internationally, as well as bogs, fens, floodplain
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grazing marsh and wet woodland habitats. The catchment also contains a diverse range of river systems, varying from the chalk stream of the Wey North to the clay-based systems in the lower catchment. The CAMS places great emphasis on the current water abstraction regimes impacting on SSSIs, which is a key issue within the area as the majority of water resources are derived from groundwater sources. The CAMS also categorises the Wey Catchment as ‘No Water Available’. This effectively means that the catchment is at capacity in terms of the current abstraction practices occurring. On face value, it is debateable whether the EA will be willing to license any further abstractions from the underlying aquifer to support the development of the eco-town, as this could potentially have implications for designated sites. 3.2.4
Final Water Resource Management Plan, South East Water (2011)
South East Water’s Water Resources Management Plan, sets out how the company plans to ensure appropriate security of water supply from 2010 to 2035, in the face of increased pressures from housing and population growth, climate change and environmental protection. The plan concludes that with forecast housing growth, climate change impacts and environmental requirements, and appropriate allowances being made for planning headroom,
there would be insufficient supply to meet demand within the planning period to 2035. The company is therefore rolling out universal metering and enhanced leakage management across their resource management zones, and a package of water efficiency and resource development schemes. It is forecast that by 2030, including for the inflating effects of climate change, households will have an average consumption of 166.4 l/h/d, compared to 180.1l/h/d without the measures. Over 70% of the water the Company delivers comes from groundwater, from more than 250 boreholes and wells. The remainder comes from surface water sources, from six river intakes and from six surface water reservoirs. A total of 8% of the Company’s supplies is imported from sources owned and operated by other water companies, under joint rights or bulk supply agreements. This makes the Company the highest net importer of water of any water company in the South East region. Furthermore, the Company derives the highest proportion of its available supplies from imports, when compared to any of the other water companies in England and Wales. The whole of the Company’s supply area falls within a wide region designated by the EA as being an area of serious water stress. A total of 20% of the Company’s water resources are taken from areas defined as ‘over abstracted’ in the EA’s CAMS
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Assessment, with 32% being within areas defined as being ‘over licensed’.
supply systems and alternative waste management arrangements to enable anaerobic digestion.
Whitehill Bordon Eco-town is located within SEW’s Resource Management Zone 5 (RMZ 5), which is forecasted to remain in surplus for the whole of the planning period to 2035 with the development of two groundwater schemes, Greatham (AB) and East Meon (AB) at the end of the planning period. Some of the surplus from RMZ 5 is exported for use to support RZ4 for the duration of the planning period.
3.3.2
East Hampshire District Council Strategic Flood Risk Assessment (SFRA), Halcrow (November 2008)
The SFRA was completed by Halcrow in 2008, in accordance with PPS25, to provide evidence for the Local Development Framework.
3.3 Local Policy
The SFRA confirms that in certain locations the permeability of the Wey catchment means that the River Wey is classified as a groundwater fed river, and in some instances, flooding can be exacerbated by the high baseflow contribution.
3.3.1
East Hampshire DC Core Strategy Preferred Policies Document, EHDC (November 2009) Policy WH5 on reducing Energy and Water Consumption requires that development should address all aspects of the water cycle and “achieve water neutrality (achieving development without increasing overall water use across a wider area).
Hydraulic modelling of the River Wey has been completed, and the EA Flood Zones have been updated to include Flood Zone 3b (functional floodplain) for the main river reaches. In addition to this, the SFRA provides a chronology of historical flooding episodes across the district. Fluvial floodplains are indicated to run along the western and eastern borders of Bordon and Whitehill.
In line with PPS25, the strategy also specifies that there must be no increase in surface water runoff as a result of development and developers should aim to reduce this where possible.
The SFRA makes a number of recommendations for development that is within/ applies to the study area:
The document indicates that there is scope to investigate the potential to manage water supply with an ‘Inset Appointment’, which would allow the installation of rainwater harvesting, dual
Development must take into account the potential for groundwater flooding.
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Development planning should include measures to avoid development on floodplains, using techniques such as providing alternative floodplain storage or use of SuDS.
All surface water drainage systems need to consider the requirements in the document ‘Rainfall runoff management for developments – Interim national procedure’ including controlling the peak rates, the additional volume, and exceedance.
An assessment of overland flows and temporary flood storage across the site will also need to be undertaken.
Wherever possible, floor levels should be situated a minimum of 300mm above the 1% with climate change flood level.
Safe access and egress should be from the individual buildings to an area wholly outside of the floodplain using public rights of way.
No development will be allowed unless it is demonstrated that:
‘Safe’ access is dry for ‘more’ and ‘highly vulnerable’ uses.
a) dry access and egress is provided,
Development on Greenfield sites will be expected to mimic the existing Greenfield drainage conditions.
Development on Brownfield sites will be expected to make a positive reduction to revert the site back to Greenfield conditions unless for exceptional reasons agreed with East Hampshire District Council and the Environment Agency it is not possible or reasonable to achieve this.
b) the receiving watercourse has sufficient capacity and, c) flood risk is reduced where possible, or at least not increased, in the development and in surrounding areas’.
Development proposals should demonstrate no increase in: Catchment Flood Management Plans (CFMPs) The East Hampshire District lies within three CFMP catchments; the Thames (for the River Wey), the South East Hampshire (Meon River and Lavant Stream) and the Arun & Western streams (River Rother) catchment.
3.3.3 a)
The peak rate of storm water runoff leaving the site.
b)
The volume of runoff leaving the site.
c)
The pollution load to receiving waters from storm water runoff by following the SuDS ‘management train’.
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The River Wey within the study area, falls under the Rural Wey Policy Unit from the Thames CFMP, which is predominately comprised of underdeveloped floodplain. The policy unit recommends the following action:
Maintain the capacity of the undeveloped natural floodplain.
Seek to enhance the capacity of the undeveloped natural floodplain. Recognising that this will require structural measures.
Align the objective of maintaining or enhancing floodplain capacity with expansion and enhancement of floodplain environments.
Continue to reduce the impact of low order flooding in urban areas (up to a 10% to 20% AEP flood – 1 in 10 to 1 in 5 year return period) by maintaining conveyance where it is both effective and sustainable to do so.
Reduce the consequences of flooding through continued action to raise public awareness.
Safeguard the existing undeveloped natural floodplain through the appropriate application of the Sequential Test within PPS25.
Maintain, or in some cases re-establish, river corridors so that urban areas can better accommodate flooding (location and layout) and the buildings are more resilient to flooding.
Develop and establish a ‘water exclusion strategy’ – where emphasis is placed on minimising water entry whilst maintaining structural integrity, and on using materials and construction techniques to facilitate drying and cleaning.
In those locations where the level of flood risk merits direct intervention, progress those options that are the most effective and sustainable long term.
4 BLANK
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4 Water Neutrality 4.1 Achieving Neutrality
Offsetting demand through retrofitting of existing development (commercial or domestic) with water efficiency improvement measures
Innovative methods of water charging and universal metering
Education of the local population in methods and benefits of water efficiency measures and reducing water consumption.
National Guidance
4.1.1
Increased housing demand and development pressures in areas suffering from water stress or limited water resources, has resulted in aspirations to achieve water neutrality. As climate change threatens to reduce the available water supply in certain areas of the UK, water neutrality offers the potential to use water more efficiently whilst still satisfying demand and having a benign (or potentially beneficial) impact on the environment. It is a requirement of the Supplementary Guidance for ecotowns in PPS1, that eco-towns must achieve water neutrality where they are proposed in water stressed areas. The population in England and Wales is expected to rise to ten million by 2031, and the pressures of climate change will force people to adapt to reductions in available water. A Water Neutral Development requires that the water demand of the development is met through the more efficient use of water resources rather than the creation of new resources. To achieve this model requires the roll-out of water efficiency measures, which include:
The net result of these measures should be one of water neutrality. Figure 4 illustrates this model in the context of a conceptual streetscape.
Incorporation of water efficient devices in new development
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Figure 4
Conceptual ‘Water Neutral’ Streetscape
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4.2 Defining the Zones The guidance provided in the EA’s briefing note ‘Water Neutrality: An Expanded Definition’ (2009) states that ‘water neutrality would be delivered within a pre-defined zone which encompasses the new development and a surrounding area’. The EA specifies that in many cases the water company’s water resource zone (in this case SEW RMZ5) would provide an appropriate spatial scale to consider water neutrality. However, the guidance is clear that, for some developments where the water RMZ is significantly larger than the development area, the RMZ may not be the most appropriate method of defining the zone of water neutrality. In such a case, reference should also be made to local hydrological information, the local Catchment Abstraction Management Strategies (CAMS) and other water resource studies.
Whilst the Zone of Water Neutrality is easily defined, the following section describes the supporting information which has been used in the delineation of the Zone of Influence. During this process, it was important to consider not only the local hydrological and hydrogeological regime, but also consider the surrounding habitats, designated sites, population centres and other activities which could be influenced by the activities occurring at the eco-town. Perhaps the most critical issue raised by local stakeholders, was ensuring that the Zone of Influence considered designated and ecological important sites within the wider area. 4.2.1
Hydrological Catchments
1
The Zone of Water Neutrality – defined as the extent/ boundary of the eco-town proposals, where water neutrality must be accomplished.
The starting point to define water neutrality should be with understanding the local hydrological catchment. The site is situated within the catchment of the River Wey, which at its confluence with the Thames at Weybridge covers a total area of approximately 900km² draining parts of West Sussex, Surrey and Hampshire. At Bordon the contributing catchment area to the Wey is approximately 75km². The southern branch of the River Wey arises in the Lower Greensand of the Hythe Formation.
2
The Zone of Influence – defined as the area surrounding the eco-town that can have an influence on achieving water neutrality or be directly influenced by water management within the eco-town.
To get an appreciation of the hydrological characteristics of the River Wey catchment at Bordon, the Flood Estimation Handbook (FEH) CD ROM (version 3) has been used to obtain more detailed information relating to topography, hydrological
In the definition of the zone of water neutrality for Whitehill Bordon, two elements have been defined:
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response, land cover and annual average rainfall. Key characteristics are detailed below:
Based on the urban, suburban and impermeable bare ground coverage, the catchment is classified as ‘Moderately Urbanised’.
The standard percentage runoff is16.4%– which indicates that the underlying ground conditions offer significant permeability.
Standard Annual Average Rainfall (SAAR) for the site is indicated to lie between 850mm and 890mm depending upon location.
As part of this study, morphometric analysis was undertaken using a three-dimensional Digital Terrain Model (DTM) of the eco-town site and the surrounding area, to define the contributing catchment area (and watersheds) to the surrounding watercourses. This analysis indicated that the various segments of the eco-town site actually drain towards one of four watercourses:
The Oxney Drain (approximately 69% of the proposed ‘new’ built development discharges to this watercourse)
The Oakhanger Stream (approximately 12% of the proposed ‘new’ built development discharges to this watercourse)
Figure 5
Watersheds and drainage direction (Contains OS Data (Crown Copyright 2011))
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The Deadwater (approximately 15% of the proposed ‘new’ built development discharges to this watercourse)
4.2.2 Hydrogeology Nearly 75% of the East Hampshire District is classified as Upper Chalk downland, covering the northwest, west and southern parts of the district. The majority of East Hampshire is underlain by chalk, although there are areas of the district where sandstones and clays are more prevalent. The chalk dominated geology is also more susceptible to groundwater flooding and in the winter of 2000-2001 there were many reported incidences of groundwater flooding due to elevated water tables. More specifically, the area of Whitehill Bordon is underlain by the Sandgate formations, which are underlain by the Hythe Beds. The Hythe Beds form the lower layer of the extensive Lower Greensand aquifer. The bedrock geology at the MoD site (Zones 1, 2, 3, 6 & 7) comprises Cretaceous Lower Greensand, which comprises the Major Aquifer of the Folkestone Beds (Ferruginous sand), overlying the Minor Aquifer of the Sandgate Beds (sandy silt and clay). The Sandgate Beds are reported to have a thickness of approximately 20m (Enviros, 2003) and are underlain by the Hythe Beds (glauconitic sands). Parts of the site are covered with made ground at various depths (in some places up to 4m).
Water at the MoD site is supplied by a borehole and artesian well that are understood to abstract water from the Sandgate and Hythe beds (Enviros, 2003). The fact that the well is artesian suggests that the overlying Sandgate formations may act as a partial aquitard. Under these conditions, it is expected that streams and aquifers will be in hydraulic continuity, and groundwater levels will therefore be controlled by the level of local streams. A groundwater divide (interfluve) exists along the ridge separating the Oakhanger and Wey/Deadwater catchments. It is thought that the MoD abstraction may have a slight impact on the groundwater level at the interfluve. However, it is very unlikely that the MoD abstraction will affect the level of groundwater in the adjacent Oakhanger catchment (and therefore have any effect on the designated sites lying adjacent to the Oakhanger Stream). There are three EA Groundwater Source Protection Zones (GSPZs) within the vicinity of the proposed eco-town. The zones are associated with the groundwater abstractions from the SEW supply boreholes at Headley Park and Oakhanger. However, the Total Catchment and Outer Zone of each GSPZ does not encroach into the eco-town boundary. Figure 6 provides an extract of the EA GSPZ mapping for Bordon and the surrounding area. The EA report that groundwater is relatively shallow below ground level across the site. The Folkestone and Hythe are both designated Principal aquifers and are used in the area for
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potable abstractions. The EA report that there are no GSPZs within the town boundary but the GSPZ 3 for SEW’s abstraction at Headley Park is at the boundary to the town. The private abstraction for the MoD site doesn’t have a GSPZ. The EA also recommends that if this abstraction is used for potable supply for the new town it does need to be considered that any discharges to ground in the vicinity of the abstraction could have a detrimental effect on the quality of that supply. Maps of the bedrock and superficial geology for Bordon and the surrounding area are provided in Drawings 24763/001/001 to 003 in Appendix A. 4.2.3
Designated Sites and Conservation Areas
Woolmer Forest Woolmer Forest is located immediately to the south of the current MoD site (south of Zone 5), and has SSSI, SAC and SPA designations. The forest straddles the A3 between Greatham and Liphook and covers an area of approximately 1,400ha, of which 600 ha is heathland. The Woolmer Forest SSSI also comprises Conford Moor and Passfield Common. For the purposes of this study and following stakeholder consultation, Passfield Common and Conford Moor have been considered separately. The heathland is typical of the remaining heathland in the surrounding area forming largely on the Folkestone Sands.
Figure 6
EA GSPZ Mapping for Bordon (Downloaded April 2011 from www.environment-agency.gov.uk),
The forest has been used by the MoD for training exercises over the past 200 years, and as a result of this the area has been subject to widespread drainage practices. However, in recent years the MoD has changed their approach in recognising the natural importance of the site as an area of lowland heath in supporting wildlife. There have been attempts to restore some valley bogs.
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Woolmer Pond, purported to be the largest ephemeral lake in Europe, is located within the Forest. In the publication ‘Flora of Hampshire’ (HIoW Wildlife Trust, 1996) it is reported that in the early part of the 20th century the pond had clear, weakly acidic, low nutrient water. However, the construction of a military railway along the western edge of the pond is thought to have transformed the environment into a highly acidic sphagnum swamp through wash off sand and sediment from the railway embankments. Attempts have been made in recent years to clear the pond of these peat-forming layers of vegetation. The same publication reports that the base of the pond is impervious, suggesting that there is no interconnectivity between the pond and the underlying groundwater system. This notion is supported by local stakeholder knowledge of the wetland system. Water levels in the pond would appear to be maintained through surface level flows, either directly or through infiltration of the surrounding sands and gravels. The topography indicates this catchment of the pond extends to approximately 76 ha and its characteristics will be most influenced by changes to land use patterns within this area. Shortheath Common The Common is located immediately to the west of the Oakhanger Stream, between the settlements of Oakhanger and Kingsley. The Common itself is approximately 1km to the north west of the MoD site and has SAC and SSSI designations. The protected area designation was granted based upon the waterdependent habitats and species which include birch woodland
and very wet mires often identified by an unstable 'quaking' surface. The Common comprises an extensive coverage of floating sphagnum (quaking) bog. The area is thought to have been dominated by open water/ meres before colonisation by sphagnum moss. Part of the common includes an area of birch woodland and bracken, typical of lowland heath. Broxhead and Kingsley Commons These commons are located immediately to the north of Bordon and have SSSI and SPA designations. Kingsley Common is occupied by the MoD and is used for exercise training. The heathland is reported to have a particularly rich bryophyte and lichen population (HIoW Wildlife Trust, 1996). Along the south side of the common there is a sandstone ridge which has been colonised by oak woodland. Bramshott and Ludshott Commons Both commons have SPA and SSSI designations, are located to the south east of Bordon and approximately 5km to the east of the MoD site. The commons are separated from Bordon and bisected by the Deadwater and River Wey valleys. Ludshott Common is a local area of heathland within the ownership of the National Trust. The heathland itself is located on the Hythe Beds. However, there are no wet-heath environments, which suggest that the heathland is not sustained
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by groundwater upwellings from the Hythe Beds. Bramshott Common is of a similar nature in terms of the habitat and vegetation coverage. Passfield Common and Conford Moor Passfield Common and Conford Moor actually form part of the Woolmer Forest SSSI, but for the purposes of reporting have been considered as separate sites, owing to the importance of the sites expressed by local stakeholders. Passfield Common and Conford Moor forms part of the National Trust property ‘Passfield Common and Conford Moor’. Conford Moor is located at the headwaters of the Hollywater, which is a tributary of the River Wey. The SSSI designation was granted due to the ecological importance of the moor in terms of the wet heathland, wet woodland and alkaline fen. In recent years, the National Trust has completed hydroecological investigations to aid in the restoration of parts of the estate. According to the ‘Conford Moor SSSI: Reconnaissance Hydro-Ecological Study’ (National Trust, 1997), parts of the site are dominated by groundwater flow. In the lower areas of the Hollywater valley where groundwater flow from the Sandgate Beds (which originates from the calcareous geology of the Bargate Beds) is intercepted by the watercourse, the soils are permanently saturated with low nutrient, alkaline water. In these wetter areas a well humified layer of peat exists. The alkaline groundwater appears as sequence of seepages and seasonal streams, which have a particularly low nutrient concentration, typical of mesotrophic conditions.
Through consultation with the National Trust, Conford Moor and Passfield Moor are reported to have suffered historically from ‘drying out’ which has led to a reduction in heathland habitat and associated flora. It is understood that the National Trust have implemented a series of measures to secure water resources to the moor through drainage diversion and damming. The National Trust are insistent that the eco-town must not have a detrimental impact on water resources within the estate, as further abstractions may have negative impacts on the restoration strategy. Deadwater Valley The Deadwater Valley forms a Local Nature Reserve (LNR), which runs through the Parish of Whitehill (Zones 3-5). The valley tracks the course of the Deadwater and the built development surrounding it to the confluence with the River Wey. The valley is used extensively by the local population for recreation and contains many ancient woodland species and serves a further purpose as wildlife corridor. The Deadwater Valley Trust is responsible for the management and improvement of the LNR. 4.2.4
Population Centres
One of the overarching aims of the eco-town is to draw in funding, investment and prosperity to the wider district. This includes the population centres of Headley Down and Headley. It is imperative that these adjacent local centres are included/ considered as part of any future policy on water management
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for the eco-town. Current and future water management operations within these settlements have a direct bearing on the success of achieving water neutrality and the ‘good status’ as required by the WFD. It is recommended that water efficiency measures and retrofitting options are made available to these local populations. The combined effects of such measures will see a reduction in water demand and consumer costs, and potentially a reduction in quantum of water abstracted from SEW’s two principal sources in the areas (Oakhanger and Headley boreholes). Such measures can only reduce the environmental impacts to the underlying aquifer. 4.2.5
Final Zone
The final zone of influence is based upon an interpretation of the information described in the previous sections. From a hydrological and ecological perspective, the Zone of Influence has been extended towards the south to include the headwaters of the Hollywater and Deadwater catchments at Woolmer Forest, so the water resources and habitat at this location are considered in the formulation of any policy. In a similar vein, Passfield Common and Conford Moor have also been included, owing to the sensitivities and recent restoration works to the groundwater fed habitats. The decision was made not to include Bramshott and Ludshott commons within the Zone, as there is no obvious hydraulic connectivity between present and future operations at the site, and the
hydrogeology at the commons. It is understood that the Hollywater and River Wey valleys will have the major controlling influence on any groundwater flow from the Hythe Beds. Due to their designated status and importance in terms of natural heritage, Shortheath Common along with Broxhead and Kingsley common have also been included. Their location downstream of the site along the Oakhanger and Oxney Drain watercourses makes the sites potentially susceptible to water management measures implemented within the eco-town boundary (e.g. treatment, discharges). The boundary has also been extended to include the population centres of Headley Down and Headley. Although not part of the eco-town development, it is of great importance that the population within these settlements are not alienated or omitted from the wider sustainability objectives of the eco-town. Potentially, measures such as universal metering, water efficiency devices and stepped tariffs could be distributed throughout Headley, Headley Down and Lindford to achieve water neutrality for the eco-town, whilst having additional cost savings and sustainability benefits for the inhabitants. Finally, the neutrality boundary has been extended towards the east and north east to include the SEW public water supply abstractions from the Headley boreholes, as well as the outer edge of the ‘Total Catchment’ of the EA Groundwater Source Protection Zone (GWSPZ) for this abstraction.
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4.3 Stakeholders At the stakeholder workshop (1st March 2011) representatives from Whitehill Town Council, the EA, SEW, TW, NT and other interested parties were asked for their thoughts and opinion on PBA’s approach to defining both the Zone of Water Neutrality and the Zone of Influence. Before progressing with any technical assessment it was imperative that local stakeholders were both understanding of the approach taken to define these zones and in agreement with the final boundaries. Stakeholders had the following comments on the definition of these zones:
Stakeholders were in agreement that the extent of the zones was acceptable and were happy to see that Woolmer Forest had also been included.
Suggested that the local population at Headley and Headley Down should be included in the eco-town proposals in some form (e.g. in relation to water these communities could be included as part of the retrofitting of existing properties with water/energy efficiency measures).
this manner, local inhabitants aren’t made to feel alienated from the eco-town proposals. The final boundaries for these zones are included in Figure 24763/001/004 in Appendix A and the notes from the Stakeholder Workshop are included in Appendix D. These boundaries have been used in the consideration of water management measures, technical assessment and policy drivers. In depicting the boundary, the line which defines the zone of influence has been drawn along features which should be visible on the ground (e.g. roads, footpaths, buildings, fences, etc). Whilst this is not a critical issue it is important in the long term for engaging people in understanding the nature of the water cycle and how they can contribute to the protection of this vital resource in a definable area. The extent is shown as shaded to indicate that it is not an absolute and those on the periphery should still be considered part of the eco-town process.
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Suggested that there shouldn’t necessarily be a ‘fixed’ boundary, as local residents may not respond well to an immovable line. In terms of policy, the extent of the zone of influence should reflect a relaxation in water management measures with distance from the eco-town. In
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5 Environmental Protection 5.1 Designated Sites Sites and Habitats A detailed description of the designated sites and significant habitats in the wider area is provided in Section 5.3.3. This section outlines the most ‘at risk’ sites and habitats, according to supporting information and stakeholder knowledge. Potentially Affected Sites
5.1.1
It is essential that development proposals do not have a detrimental impact on the watercourses and wetland habitats within the wider area in terms of water quality (biological and chemical) and quantity. In light of supporting information and extensive liaison with conservation groups in the local area, the following sites are deemed to be the most at risk from the ecotown development.
Kingsley and Broxheath Commons
Passfield Common and Conford Moor
Deadwater Valley
Kingsley and Broxheath Commons Kingsley and Broxheath commons are potentially at risk from upstream influences at the MoD site. Although there have been no reported pollution incidents which can be attributed to the MoD operations, the development of the site could potentially mobilise sediments and contaminants and increase downstream flood risk along the Oxney Drain, which may potentially reach these habitats. The commons are both SSSIs and form components of the Wealden Heaths Phase II Special Protection Area. The Land Quality Assessment Report (Enviros, 2003) states that both these sites are designated as ‘important ecologically’ to:
Diversity of habitats supporting rich invertebrate fauna, including 25 rare species
Rich flora
Three species of birds listed in Annex 1 of the EC Directive on the Conservation of Wild Birds.
Passfield Common and Conford Moor Passfield Common and Conford Moor have been identified as suffering from a lack of available water. Whilst the NT has undertaken remedial works to alleviate ‘drying out’ of parts of the moor and noticeable improvements in habitat and species richness have been observed, it is imperative that the demand
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for potable supplies from groundwater abstraction does not draw upon the natural supply of groundwater from the Sandgate Beds. However, it is unlikely that there is a direct continuity between the abstraction at the MoD site, which is taken from the Hythe Beds, and the groundwater source for the common, which is understood to be principally sustained by the Sandgate Beds. As noted earlier (Section 4.2.3) these geological features are separated by an aquitard of generally impermeable strata which acts as a major resistance to movement of water between them in this vicinity. Deadwater Valley The Deadwater Valley LNR is purported to receive inappropriate connections from waste water drainage (i.e. detergents present in the river). In certain instances grey coloured water and detergents have been observed within the channel. The Deadwater Valley LNR is an important local ecological reserve, which offers recreation and a safeguarded habitat for local wildlife. The discharge of untreated foul effluent from such sources (i.e. dish washing, showers, clothes washing) reduces the oxygen levels and can increase the concentrations of limiting nutrients within the aquatic system. Such nutrients can increase the biological productivity in a system, favouring some species but reducing overall biodiversity. Under higher loadings, such discharges may lead to eutrophic conditions.
5.1.2
Policy Compliance
It is essential that development proposals do not have a detrimental impact on the watercourses and wetland habitats within the wider area in terms of water quality (biological, chemical, and quantity). To comply with regulations under the Habitats Directive and ensure ‘no deterioration’, the proposals must demonstrate there is no change in the delivery, quality and quantity of water supplied to the designated sites as result of the eco-town proposals. In the EA’s review of abstraction consents under the Habitats Directive it was demonstrated that the current licensed abstractions within the vicinity of Whitehill Bordon, did not impact upon the European designated sites. The EA has stated that this assessment did not include the additional impact of the existing MoD abstraction even though it has been present for many years. Although the Whitehill Bordon Habitats Regulations Assessment (HRA) screened out any water related issues associated with the development of the eco-town, it is recommended that a longterm monitoring study is set up to ascertain the existing hydrogeological regime of Whitehill Bordon and the surrounding locality and the interactions with the designated sites. This should be undertaken to be certain that the development proposals will not have a detrimental effect on the designated sites at a later stage. As part of this assessment the impact on ecological sites should be assessed according to the EA’s macroinvertebrate, fisheries and macrophyte data and
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include a summary of the impacts on species of principle importance for biodiversity. However, it may be argued that maintenance of the status quo (i.e. maintaining the current level of abstraction from the MoD boreholes) can achieve the ‘no deterioration’ status under the Habitats Directive, as this will not have a detrimental effect on the designated sites and there will be no change in the groundwater abstraction quantum.
Recommendations:
A long term hydrogeological monitoring study should be undertaken to identify groundwater flow pathways and define the interactions of current groundwater abstractions and water management activities on designated sites – this is essential to guard against any potential impacts on habitats as a result of future development, to satisfy the requirements of the Habitats Directive. The EA recommend that this study also takes into consideration any proposed discharges to ground and surface water, as it needs to be shown that any changes in the proportions of water discharged to receiving systems will not have an impact on controlled waters in the area.
Subject to the findings of the hydrogeological study the base position must be that there should be no increase in the daily volume of water abstracted from the MoD boreholes to achieve the ‘no deterioration’ status as specific in the Habitats Directive.
A robust construction management plan should be implemented during all construction and demolition phases of the development to ensure that there is no mobilization/ leaching of contaminants into the aquifer,
Issues & Recommendations
5.1.3 Issues:
Any increase in groundwater abstraction at the MoD site or at any of the other SEW groundwater supply boreholes could potentially have a detrimental impact on designated sites, by reducing the quantity of available groundwater resources.
Conversely any reduction in abstraction could lead to higher water tables and increased flooding of vulnerable sites.
The NT is particularly concerned about water management practices ‘un-doing’ their restoration works at Passfield Common.
Construction/ demolition activities could lead to mobilization of contaminants at the MoD site and increase flood risk.
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no increase in downstream flood risk and no release of polluting material into the receiving watercourses.
5.2 Water quality 5.2.1
Site Sensitivity
The MoD site is predominantly underlain by the Folkestone Beds (sandstone) which comprise a Major Aquifer. Site investigations undertaken by Enviros in 2003 state that the soil classification across the site has a high leaching potential. Therefore, any contaminant release to the ground may affect groundwater and surface water quality at the site and the wider area, including the watercourses of the Oxney Drain, the Deadwater and the River Wey. The water abstracted from the MoD boreholes (St Lucia and Quebec) in Zone 3 is generally of good quality but is iron rich. The treatment works operated by Brey is predominantly an iron removal plant before the water is put into supply. There is an issue with occasional bacteriological contamination at the St Lucia supply borehole, which abstracts water from the Sandgate and Hythe Beds. Contamination of the St Lucia borehole has been shown to occur mainly in the summer months, which requires additional disinfecting (Enviros, 2003) and in some cases the recorded bacterial activity is in excess of the Drinking Water Standards, although there have been no
exceedances of treated water It is possible that the discharge from the TW Bordon Sewage Treatment Works (STW) (Zone 3), which is approximately 150m upstream of the borehole, may be leading to elevated levels of bacteriological contamination, although no studies have been undertaken to determine this as the contamination source. The Land Quality Assessment Report (Enviros, 2003) for the MoD site states there is also some concern that the screening surrounding the well may have deteriorated and water may be able to enter the borehole at shallower depths. It is very possible that contamination from the River Wey may be entering the borehole at shallower depths through the Alluvium and Valley Gravel deposits. To fix the contamination issue it is likely that the well screening will have to be repaired and an investigation completed to confirm and trace the source of the bacteriological contamination. Watercourses According to the Land Quality Assessment Report (Enviros, 2003), the Bordon Camp Stream, Oxney Drain, Oxney Stream and Oakhanger Stream are not graded by the EA in terms of water quality. The Deadwater, the River Wey (between the Deadwater confluence and the confluence with the River Slea) and the Oakhanger Stream have a ‘moderate’ ecological quality status under the WFD, according to the most up-to-date EA datasets. Upstream of the confluence with the Deadwater, the ecological status of the River Wey is classified as poor. 5.2.2
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Figure 7 provides an extract from the EA’s mapping of current ecological quality for the Bordon locality.
deterioration in water quality, but also improving water quality where practicable.
There is currently no available information from the EA on the chemical quality of the River Wey, Deadwater and Oakhanger Stream using the WFD classification.
Of concern to the EA is the current poor status of the River Wey South for elevated concentrations of phosphorous. It is thought that the discharge of treated effluent into the River Wey from the Bordon STW may be a potential phosphorous source. Whilst the EA are keen to reduce phosphorous concentration, they are mindful that phosphorous removal technologies are particularly expensive and the cost/benefit of imposing tighter phosphorus consents on the Bordon STW needs to be understood. The carbon and energy costs associated with these processes can often have their own economic and environmental consequences, as phosphorous removal is particularly energy intensive.
Figure 7
EA’s current mapping of ecological quality for rivers (www.environment-agency.gov.uk – 18/03/2011)
5.2.3
Stakeholders
The EA has confirmed in their correspondence that one of the main focuses of the WCS should be delivering the objectives of the WFD, notably achieving “good” status by the due dates. It is a requirement of the WCS to place emphasis on preventing
Proposals for improvements in phosphorous removal can be explored with appropriate and potentially innovative technological solutions, but the final technological solution will in part be dependent upon the requirements of the discharge consent for the works and cost implications. Discharge consents would need to address the biological and hydrological capacity of the receiving watercourses and components identified in the WFD in terms of achieving good chemical (phosphorous) and ecological status. 5.2.4
Water Companies
SEW has confirmed that they hold no official records of reported incidences of poor water quality within the area.
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Stakeholders have however reported separate incidents of ‘brown sludge’ within the potable water system, although they cautioned that these incidents may be attributed to temporary construction during reinforcement works within the potable water distribution network.
RECOMMENDATIONS:
Further ground investigation and soakaway testing is required at various locations throughout the site to confirm the presence of contaminants, the leaching potential of the soil and identification of any areas of the site that are or are not suitable for infiltration drainage measures. Ground investigation should take place following the MoD’s completion of decontamination and remediation of the site, under their statutory obligation. These investigations could either be completed by the eco-town special purpose vehicle, or could potentially be allocated to developers.
Whether or not the MoD boreholes are used to supply the eco-town with a potable water supply together with the mitigation of impacts caused by any increase or decrease in abstraction, the casings should be checked and repaired to ensure there is no continued contamination of the boreholes. Should they cease to be used they will need to be effectively sealed to prevent uncontrolled discharge of iron-rich water into the Deadwater which is possible under the artesian conditions at the borehole.
Alternative measures are required for the treatment and discharge of foul water to tackle the issue of elevated levels of phosphorous in the River Wey. Such measures may include the installation of a new STW in a new location or upgrades to the existing STW at Bordon. The installation of a new works would require interim waste water treatment reinforcement measures to be employed in the locality
TW has not reported any significant issues with water quality associated with their treatment processes in the wider area and there is no record of breaches of discharge consent in the recent past, but note comment in 5.3.2 below. 5.2.5
Issues & Recommendations Recommendations
ISSUES:
The site soils have a high leaching potential, which could impact the potential to use infiltration drainage measures on a site-wide scale should sources of contamination be present
The borehole casing at St Lucia borehole may be leaking
Bordon STW could be the cause of elevated levels of bacteriological contamination into the St Lucia borehole
River Wey South is of ‘Moderate Ecological Status’ as defined under the WFD, and is suffering from elevated levels of phosphorous – Most probably attributable to the discharge from the Bordon STW
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during the development phasing to support this. Furthermore, careful consideration needs to be given to the type of water treatment technology employed at a new works or Bordon works, and this needs to be based on a fixed EA discharge consent which can be monitored and compared against standard water quality indicators under the WFD, to work towards achieving good chemical and quality status of receiving systems.
5.3 Pollution control 5.3.1
MoD Site
Arsenic concentrations at the site within the Folkestone Beds and areas of Made ground are shown to vary between <1 mg/kg to 446 mg/kg (Enviros, 2003). This demonstrates that in some locations of the site, the arsenic concentration exceeds the Soil Guideline Value (SGV) for residential end use. Further ground investigation demonstrated that the US95 value for Arsenic was below the SGV for Arsenic (20mg/kg). Therefore, the average concentration for Arsenic across the site is below the SGV for residential use and not thought to present a risk to human health. Reported incidences of foul water flooding of the Trenchard Army Houses, towards the east of Whitehill Bordon (Zone 3), needs to be rectified as part of any development proposals (i.e. removal of cross connections). Stakeholders are interested in
investigation of the response of the sewerage system to rainfall events. As part of the MoD Land Quality Assessment conducted by Enviros (2003), a qualitative assessment of the pollution risks to various locations of the Bordon site was conducted. Table 1 provides a breakdown of the pollution risks and recommendations for development. The major sources of pollution are associated with human exposure to hydrocarbons, heavy metal, asbestos and radiological material during demolition and construction phases. There are also unconfirmed reports that throughout the MoD site there are informal landfill areas, where artillery and tanks are purported to have been â&#x20AC;&#x2DC;buriedâ&#x20AC;&#x2122;. If these areas do exist, then they represent an unknown quantity in regards to pollution control. Heavy metals, hydrocarbons and radiological material associated with defence machinery can present a significant risk of contamination to the underlying aquifer and potable water supplies. However, the MoD has a statutory duty to remove sources of contamination from the site and decontaminate the site where practicable, before the land transfers from the ownership of the MoD. From discussions with the eco-town project team, it is apparent that decontamination will extend to all MoD sources of contamination such as radiological contamination, some heavy metals and asbestos, but it is unlikely to include hydrocarbon removal.
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Location
Human
Groundwater
Designated Sites
incidents were classified as minor the actual details are unknown.
Slab, Hogmoor, Southern Railway (PBA Zones 66-7)
No Sig. Risk
No Sig. Risk
No Sig. Risk
Moderate/ Low Heavy metals, asbestos, PAHs Moderate/ Low Heavy metals, asbestos and PAHs
Moderate/ Low Heavy metals, asbestos, PAHs
No Sig. Risk
No Sig. Risk
No Sig. Risk
The EA online pollution records indicate that in June 2002 there was a pollution incident classified as a ‘Major Impact’, which appears to be associated with Bordon STW (Zone 3). A ‘Major Impact’ is defined as having persistent and extensive effects on the quality of the environment, which may cause major damage to the ecosystem, agriculture and/or commerce, and have serious impacts upon the human population. The pollutant involved with this incident was not identified.
High Asbestos
No Sig. Risk
No Sig. Risk
Moderate/ Low Benzoapyrene
No Sig. Risk
No Sig. Risk
Louisburg Barracks (PBA Zone 2) Martinique Barracks & Northern Railway St Lucia Lodge and RE Lines (PBA Zone 3) St Lucia Wood and former Laundry
Moderate/ High No Sig. Risk Radiological contamination Table 1 Qualitative assessment of pollution risks (Adapted from source: Enviros, 2003) Training Area & Prince Phillip Barracks
Moderate/ High Radiological contamination
Locality According to the MoD Land Quality Assessment (Enviros, 2003) there has been a total of 22 pollution incidents within the vicinity of the MoD site, which have been recorded by the EA. Six of these incidents were located within the MoD site itself and the other 16 were within 250m of the site. Although these 5.3.2
Table 2 and 3 display the details of the total amount of contaminants released to the air and watercourse from the Bordon STW using the most up-to-date information from the EA website. The tables use the EA’s 2009 dataset. Substance
Release Total Released Notifiable Releases Environment Ammonia Air <1000kg N/A Methane Air <10000kg N/A Carbon Dioxide Air <10000000kg N/A Table 2 TW total annual contaminant release for Bordon STW Releases to Air (Source: www.environment-agency.gov.uk – 18/03/2011)
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Substance Nickel
Release Environment
River
Total Released <20kg
Notifiable Releases N/A
Ammonia River <945kg Arsenic River <5kg Cadmium River <1kg Zinc River <100kg Copper River 39.7kg Phosphorous – as total P River 6420kg Total organic carbon (TOC) River <50000kg Chlorides – as Cl River <2000t Mercury River <1kg Table 3 TW total annual contaminant release for Bordon STW Releases to Water (Source: www.environment-agency.gov.uk – 18/03/2011)
One of the problems affecting the Bordon STW is that of odour and odour control. The EA are publishing a Draft Odour Management Guide at the end of March 2011 which should assist in providing advice on odour management for the STW. Bordon STW is relatively old with high energy demands for the treatment level achieved. In the Outline WCS, the capacity of the works was identified as something that needed to be increased. The STW currently treats wastewater from approximately 41,500 PE (Population Equivalent) and handles a DWF (Dry Weather Flow) of 8,790m3/ day. It receives flows from a wider area than the immediate catchment of Whitehill Bordon.
N/A N/A N/A N/A N/A N/A N/A N/A N/A
The present EA Discharge Consent for Bordon STW is: - Suspended Solids: Solids:
25 mg/l
- Biological Biological Oxygen Demand:
10 mg/l
- Ammonia:
4 mg/l
- Phosphorous:
1 mg/l
- Iron:
4 mg/l
- Aluminium:
4 mg/l
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5.3.3
Issues & Recommendations
Remove cross connections of surface water and foul water sewers. These may be in various locations and may need to be identified as part of a survey of sewers and drains, particularly where properties are not subject to major refurbishment, such as in the existing town. Further details of what would be involved in an investigation to identify cross connection are provided in Section 11.
Alternative measures are required for the treatment and discharge of foul water to tackle the odour issues at the Bordon STW. Such measures may include the installation of a new STW or upgrades to the existing works.
ISSUES:
Elevated concentrations of arsenic in certain locations throughout the site.
Potential high risk of exposure to hydrocarbons, radiological material, heavy metals and asbestos during the demolition/ construction phases of the development.
Cross connection of sewers and pollution incidents on the Deadwater.
Odour issues concerning the Bordon STW.
RECOMMENDATIONS:
A robust waste management plan needs to be put in place during the construction and demolition phases of the development to ensure that there is no dispersal or mobilisation of contamination on the site from heavy metals, radiological materials, hydrocarbons and asbestos. Such a plan should also ensure there is no deterioration in the habitats and ecology of designated sites. Of particular risk are the downstream sites of Kingsley and Broxhead commons where mobilisation of contaminants could have a detrimental impact.
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6 Water Resources 6.1 Groundwater Existing groundwater abstraction in the wider area can be grouped into three classifications: 3
Ministry of Defence (MoD)
4
South East Water (SEW)
5
Private Supplies
The following section provides information on each one of these existing abstractions: 6.1.1
Ministry of Defence
Groundwater at the MoD site has been shown through site investigations to lie approximately 4m below the surface and flows in a north easterly direction towards the River Wey (Enviros, 2003). Potable water for the private MoD supply to the military personnel, their housing and associated training uses is sourced from two groundwater abstractions: a borehole (known as ‘Quebec’ [Zone 3] – the principal source) and a well (known as ‘St Lucia’ [Zone 3] - used for backup purposes) situated within the MoD estate perimeter close to the Deadwater. This supply also serves fire hydrants and washing and cooling functions for the MoD.
There is a complex relationship between the owners and the operators of the boreholes. Project Aquatrine, a Private Finance Initiative (PFI) set up by the MoD, was awarded to Kelda Water Services in 2003 to deliver water services over a 25 year period. This will need to be taken into consideration in future negotiations with regard to the ownership, retention and use of existing infrastructure at the MoD site. The borehole and the well are considered to be entirely unconnected to the civilian population areas and solely serve the MoD estate. The combined abstraction volumes from the two sources vary between 0.6 and 1.5Ml/day (Enviros, 2003). Based on the data supplied by Kelda Water Services, the borehole at Quebec Barracks provides on average a quantity of 1.4 Ml/day. The borehole depth is 76.2m with a casing diameter of 3.5m. Since the boreholes are situated within the military domain they are not officially licensed by the EA. Water quality data supplied by Kelda Water Services indicate that the groundwater abstracted from the principal borehole suffers from elevated concentrations of iron (between 500600mg/l). However, this mineral is removed at the MoD water treatment works. Precise water quality parameters for the abstracted water are not known, but it is known that the MoD contractors (Kelda Water Services) remove iron and dose with chlorine (at 0.3ppm) ‘in accordance with the Private Water Supply Regulations.
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From data supplied by Kelda Water Services it is clear that the water quality of the supply conforms to the 2009 Private Water Supply Regulations when sampled at the service reservoirs. It is reported (Enviros, 2003) that occasional bacterial contamination occurs in the St Lucia well, particularly during the summer period. Its provenance has not been conclusively determined, but such incidents are countered by the use of a higher chlorine dosing regime. Anecdotal evidence suggests that leakage from the well and contamination entering the well still occurs possibly due to the deterioration of the well casing, although borehole water quality data for July 2010 [sample available only for this month] shows no evidence of such contamination. South East Water Potable water is supplied to the civilian population of Whitehill Bordon by SEW within their Resource Zone (RZ5). The supply is predominantly obtained from a series of abstraction boreholes at Oakhanger and Headley Park. The extent of RZ5 is shown in Figure 8, with the Whitehill Bordon Eco-town boundary provided for comparative purposes. There are a 6.1.2
Figure 8
SEW Resource Management Zone 5 (GREEN) against ecotown Boundary (RED)
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total of six operational boreholes at the Headley site. Under the EA licence agreements they provide up to a maximum of 13.65 Ml/day for potable supply.
Recent SEW abstraction records show that during the period from 2010 to 2011, an average daily rate of 9.08 Ml/day was abstracted from this source. The boreholes are therefore licensed by the EA to provide a higher yield than has recently been required. The majority of this water is used to supply other parts of RZ5. The Oakhanger supply comprises 5 operational boreholes which are licensed by the EA to abstract a total of 8.18 Ml/d. Records from SEW show that the average daily abstraction from this supply during the period 2010 to 2011 was 5.0 Ml/day. Groundwater from this supply has elevated levels of iron and manganese, which requires an additional level of treatment including pressure filtration systems and chlorination. A large portion of this water is used to supply other parts of RZ5 and the adjacent RZ4
Figure 9 Extract of Resource Management Zone 5 (Source: SEW Resourced Management Plan)
All boreholes draw from the ‘Deep Sandstone’ aquifer. SEW have indicated that there is sufficient licensed headroom from this resource to provide the extra water required by the ecotown. SEW provide only one emergency (back-up) connection to the MoD site. SEW has stated that in 2007, the meter on this connection recorded a total annual supply of only 7cm³, indicating that the MoD is entirely self sufficient with their onsite boreholes. Figure 9 provides an extract from SEW’s Network Schematic for Resource Zone 5 of the BordonPetersfield area, which focuses on the connections between the Oakhanger/ Headley Park supply and the local District Metering Areas (DMA).
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6.1.3 Private Water Abstractions and Discharges Using abstraction data provided by the EA an assessment of all licensed private water abstractions which fall within the Zone of Influence has been made. Table 4 provides a breakdown of the nine private abstractions that lie within the Zone of Influence, and states the abstraction classification, location and daily / annual quantities. This table does not include any abstractions which are less than 20m³/day as such abstractions are exempt from requiring a licence. Abstraction Use
No of Abstractions
Licensed Abstraction (m³) Daily Annual 2,245 189,967 7,200 2,635,200 11,366 3,200,000 792 53,592
General Agriculture 4 Agriculture Aquaculture Fish 1 Mineral Products 1 Golf Courses 2 Horticulture and 1 252 10,000 Nurseries TOTAL Private 9 21,855 6,088,759 abstractions Table 4 Total daily and annual abstraction quantities from private licensed supplies
The total for these private abstractions amount to over 20Ml/day with the single biggest abstractions associated with mineral works and aquaculture. These account for approximately 90% of the total private water supply abstractions within the Zone of Influence. Drawing
24763/00/005 in Appendix A provides the geographical location for each of the licensed abstractions. To provide a comparison with the licensed abstractions, the discharge consent information for all licensed discharges within the zone of influence has also been obtained from the EA. The data is presented in Table 5. Table 5 Dry Weather Flow and Maximum Daily Flow Quantities for all Discharge Consents
Use
No. of Discharges
Dry Weather Flow (m³/day)
Max Daily Flow (m³/day)
Sewage
30
7,791
22,858
Minerals Minerals
1
1,500
4,500
256
769
102
306
88
266
59
177
12
34
Domestic 10 This identifies that the Aerospace and largest discharge consent 2 MoD (excluding that of the Commercial 6 Thames Water sewage Water Supply & disposal works at Bordon) 4 Treatment is associated with the Horticulture/ extraction of stone and 4 Forestry gravel, equating to a Dry Waste 12 Weather Flow of Recreational 1 ~1500m³/day. This correlates with the EA Hospitals 1 abstraction information as Undefined 2 mineral products also TOTAL 73 comprise the largest consented groundwater abstraction (3,300,000m³/ year). The second largest consents are associated with sewerage
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6
19
4
13
12
37
86 9,916
257 29,236
infrastructure and disposal works (e.g. treatment and pumping), which equates to a Dry Weather Flow of approximately ~800m³/day.
However, information from the same document indicates that the River Wey catchment is currently classified as ‘No Water Available’ or ‘Over Abstracted’, as shown in Figure 10.
Existing Constraints Using the SEW data on current groundwater abstractions it is clear that the Oakhanger and Headley supplies are operating within the limits of the EA abstraction licenses. SEW has confirmed that Whitehill Bordon area has been considered in their Water Resource Management Plan (2008) as an area of potential development and the water mains from the Oakhanger supply have been reinforced to provide potable supply in the direction of the proposed eco-town. SEW has a statutory duty to deliver a potable water supply to sustain however many houses are built as part of the eco-town. The main concern for SEW is the development phasing, and ensuring that adequate infrastructure provision is in place before the development takes place. Water availability is not of major concern as water can be imported from other sources in the resource zone to satisfy demand.
All customers of the water company are subject to the same risk of water restriction identified within the EA CAMS for the River Wey Catchment. It is understood that SEW’s plan to roll out a Universal Metering programme across the entire administrative area, with target of getting 90% of households on meters before 2020, will help to achieve a reduction in water demand to meet the resource availability.
6.1.4
According to the SEW Water Resource Management Plan (2008), “Resource Zone 5 remains predominantly in surplus for the whole of the planning period to 2035 with the development of two groundwater schemes, Greatham and East Meon at the end of the planning period. Some of the surplus in supply is used to support RZ4 for the duration of the planning period”.
Under the current EA licensing strategy, which has been informed by the Wey CAMS, there is ‘No Water Available’ within the Wey catchment. This does not mean that no additional water can be abstracted, but it does mean that further abstraction can only occur at high flows. However, in reaching this classification of ‘No Water Available’ the EA has not allowed for the existing MoD borehole supply in their quantification of available groundwater resources. The EA has requested that the WCS provide information about the options for water supply to the proposed eco-town to enable consideration to be given with regard to these boreholes as a resource.
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The Habitats Directive requires that there is no deterioration in the quality and quantity of water resources as result of development. Under the requirements of the WFD to aspire to good ecological and chemical status of water resources by 2015, and achieving good status by 2027 (where practicable) the ecotown should aim for improvements in water quality and quantity. Any additional abstractions from groundwater resources could have detrimental impacts not only on the underlying aquifer, but designated sites and aquatic systems which rely upon a steady supply of groundwater.
Figure 10 Surface Water and Unconfined Groundwater Availability (Source: South East Water’s Water Resources Management Plan, 2010 – 2035, December 2010)
The South East of England offers little opportunity for new water for abstractions due to the region suffering from ‘Water Stress’. The further complication is that current licensed abstractions may be at risk of being reduced under WFD and Habitats Regulations, to
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improve the water environment. However, in the SEW Water Resource Management Plan, it is stated that in future planning of water resources, allowances for the impacts of the WFD to not have to be accounted for in their supply forecasts.
At present, it is not clear what the impact on the aquatic environment and designated sites will be if groundwater abstractions from the SEW sources are increased.
Recommendations Therefore, it would need to be demonstrated to the EA that increasing abstractions from other supply boreholes to provide a potable water supply to the eco-town does not have a detrimental impact on the quality or quantity of water resources. One option would be to maintain the current rate of abstraction from the MoD borehole, and use this as the principal supply for the eco-town. Provided there was no increase in the volume of water abstracted, there should be no deterioration in the quantity or quality of water resources above the current situation and no deterioration in the resource or change to the impact on designated sites under the Habitats Directive. However, the EA has recommended that this is confirmed following pump tests on the borehole to determine any potential or existing impact on local surface water features. 6.1.5
A specific hydrogeological investigation is required to investigate and confirm the impacts of potential supply options on designated sites and aquatic environments
The principle of maintaining the current abstraction from the MoD borehole presents an option for supplying potable water to the eco-town, and providing that pump testing confirms that there is no existing impact on surrounding surface water features under the current abstraction practices, there should no deterioration in water quality or quantity.
6.2 Surface Water
Recommendations & Issues 6.2.1
Issues:
The CAMS classifies the Wey Catchment as ‘No Water Available’
As required by the EA, SEW has not taken into account impacts of WFD on future supply.
Current Operations Operations
The MoD site and the surrounding locality of Whitehill Bordon are drained by two separate systems:
MoD – served by private surface water drainage system
Whitehill Bordon – served by TW surface water drainage system.
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The MoD has its own private surface water gravity drainage system which comprises a network of drainage gullies, catchpits, oil interceptors and pipe drainage connections. From review of the MoD drainage records it is understood that the site currently discharges surface water via numerous connections to the River Wey and Oxney Drain. Only Trenchard and Quebec barracks (Zone 3) appear to discharge to the River Wey. Flows appear to be discharged to these two receiving systems at an unattenuated rate. Drawing 24763/001/006 in Appendix A provides an overview of the drainage catchments within the site based on the existing MoD drainage records. According to the TW asset plans, their surface water drainage network discharges to the River Wey and the Deadwater also at an unattenuated rate, at numerous locations along these two watercourses. The network appears to drain by gravity, as there are no pumping stations shown and the topography lends itself to this approach. 6.2.2
Flooding and Pollution
In consultation with TW it has been reported that a total of 26 properties within the area of Whitehill Bordon have experienced external flooding from capacity issues associated with the surface water drainage network. There doesn’t appear to be a cluster of properties in one particular location, as TW have reported that the affected properties are spread throughout the Bordon catchment. TW state that the majority of these flooding incidents occurred before 2002.
The EHDC SFRA does not report any issues with surface water flooding within the locality. Furthermore, the MoD and the EA have not reported any incidences of surface water flooding within the vicinity of Whitehill Bordon. However, local residents have drawn reference to capacity issues within the foul drainage network in times of heavy rainfall, which lead to backing up and failure of the toilet blocks in Trenchard Barracks (located to the east of the development site). This suggests there may be a cross connection issue, whereby surface water is entering the foul water drainage system or there could be some combined sewer systems on the network. Another issue reported by residents is infrequent incidences of ‘grey-coloured water’ within the waters of the Deadwater (Zones 4-5). It is likely that these incidents are a result of cross connection of foul water from bathing, showering and washing, which is entering the Deadwater via informal connections. 6.2.3
Issues & Recommendations
Issues:
Cross connection leading to pollution of Deadwater.
Surface water intrusion into foul water network, or elements of ‘combined’ drainage system in the MoD barracks.
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Recommendations:
Locate and terminate reported informal outfalls to Deadwater or incorrect sewer connections which are discharging untreated foul water to the watercourse. Upgrade existing sewerage network within the MoD areas to separate foul and surface water drainage systems.
6.3 Rainwater Hydrological Regime According to the most recent version of the Flood Estimation Handbook (FEH) – a national-scale hydrometric dataset for the entirety of the UK – the area of Whitehill Bordon has a Standard Average Annual Rainfall (SAAR) value of approximately 850mm, which is higher than the average annual rainfall for the South East of England of 700mm. 6.3.1
However, the data in FEH differs to observed rainfall data at a local scale. An analysis of rainfall data from the EA rain gauge at Bordon (located in Zone 3) for the period 1979 to 2011 has indicated that the average annual rainfall is approximately 790mm. The disparity between FEH and observed rainfall records can be attributed to the coarse-scale resolution of the FEH dataset. Analysis of the rainfall record during this period has shown that the highest monthly maximum rainfall occurs in October (average rainfall depth of 103.3mm), whereas the
driest month is indicated to be June (average rainfall depth of 44.9mm). Table 5 provides a breakdown of the monthly average rainfall depth. The UK Climate Impacts Programme (UKCIP09) – set up by DEFRA to model and forecast future scenarios of climate change and its impacts on the UK – has indicated that by the 2080s summer precipitation in the South East of England may reduce by up to 40% and winter precipitation may increase by up to 30%, as shown in Figure 11. Table 6 provides some specific figures on forecasted trends in summer and winter precipitation for the South East of England up to 2050. Essentially, UKCIP climate change forecasts predict warmer, wetter winters, and warmer drier summers. This means less summer rainfall and higher risk of drought. UKCP09: Projected changes to Precipitation and Temperature for South East England (2050) Mean Temperature Winter (°C) +2.2°C Mean Temperature Summer (°C) +2.7°C Winter Mean Annual Precipitation (%) +16% Summer Mean Annual Precipitation (%) -18% Table 6 South East Seasonal Mean Temperature and Precipitation Change (at 50th Percentile) by 2050 (Source: UKCIP 09)
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SUMMER 6.3.2
WINTER
Issues & Recommendations
Issues:
Climate change is anticipated to cause a 16% increase in Winter Mean Annual Precipitation by 2050, which could have significant consequences for the design of appropriate surface water management measures and assessment of future flood risk to the development.
A reduction of 18% in Summer Mean Annual Precipitation is anticipated by 2050, which impact on the design and function of rainwater harvesting measures.
Recommendations:
Surface water management measures and flood risk assessments must take into account the future impacts of climate change in line with current legislation, to ensure the appropriate design of management systems. In designing such systems, careful consideration must be given to the dual functionality of green corridors and implementation of a sustainable drainage strategy.
Climate change may lead to reductions in available water resources. Therefore an element of redundancy needs to be built into any water supply measures to ensure that future development has a sufficient quantity of available water â&#x20AC;&#x201C; this is particularly relevant if the final water supply strategy is reliant upon rainwater harvesting measures.
Figure 11 Seasonal Mean Precipitation Trends (at 50th Percentile) by 2080s (Source: UKCIP 09)
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6.4 Flooding 6.4.1
Fluvial Flooding
There are a number of watercourses within the vicinity of the MoD site which all form part of the natural drainage network of the River Wey catchment. A description of the hydrology of the River Wey Catchment is provided in Section 5. There are three principal watercourses in the vicinity of the MoD site:
The Deadwater (Main River)
The Oakhanger Stream (Main River)
The Oxney Drain
The River Wey (Main River)
The EA’s online Flood Mapping and the Flood Zone mapping provided in the EHDC SFRA both indicate that the MoD site is not located within ‘extent of the extreme flood’, which is equivalent to the extent of the 1% annual probability (1 in 1000 year) flood. According to Table D3, Annex D of PPS25, the site is located in Flood Zone 1 (Low Probability of Flooding) and there are no significant restrictions to the type of development that would be appropriate. However, the flood risk associated with the Oxney Drain (Zones 1, 2 & 6) has not been assessed so the online EA Flood Maps
do not take into account the flood risk from the Oxney Drain (which flows through the central part of the MoD site in a south to north orientation). As the contributing catchment area to the Oxney Drain at the northern boundary of the site is less than 3km² the catchment has not been included in the EA’s coarse resolution hydraulic model (JFLOW). There have been previous episodes of flooding associated with the Oxney Drain, which is a particularly hard engineered watercourse. It is understood that previous incidences of flooding have been associated with blockages/ capacity issues associated with culverts within the MoD site. The floodplain associated with the River Wey and the Deadwater to the east of Quebec Barracks (Zone 3) is particularly narrow. Consultation with local residents has confirmed that no properties within the Deadwater Valley have been affected by flooding from the Deadwater. There are no reported incidences of flooding from the River Wey affecting Quebec Barracks. 6.4.2
Pluvial Flooding
There are no significant issues from pluvial flooding (surface water flooding as a direct consequence of incident rainfall) within the eco-town boundary or within Whitehill Bordon itself. This indicates the sewer network has adequate capacity and the open ground has a good degree of permeability. Flooding incidents are reported in section 6.2. There are also no known flood risk management or alleviation schemes in the area.
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6.4.3
Groundwater Flooding
Although there are no specific details of groundwater flooding in the Whitehill Bordon areas, the East Hampshire SFRA reports that there have been some incidents of groundwater flooding in the locality and the groundwater emergence maps indicate a risk of groundwater flooding. 6.4.4
6.4.5 Issues:
Flood risk for the Oxney Drain has not been quantified.
The Masterplan shows the restored course of the Oxney Drain as a continuous water feature running through central part of the development, serving the triple functions of recreation, conveyance and a wildlife corridor. However, these features are entirely dependent upon the extent of the floodplain associated with the Oxney Drain.
Development within Flood Zone 3b (Functional Floodplain) will not be permitted, unless it is classified as Water Compatible Development. Development compatibility classifications are provided in Table D2 of Annex D, PPS25). Flood Zone 3b is usually taken as any land which is located within the extent of the 5% annual probability (1 in 20 year) flood, although the actual extent of the functional floodplain should be agreed with the EA.
According to EA design criteria, any floodplain storage which is lost as a result of development that is located within the extent of the 1% annual probability (1 in 100 year) with climate change flood event must have the equivalent level of floodplain storage compensation provided to offset the reduction. Built development within the floodplain reduces the amount of available storage for
Impacts of Development
Under national policy guidance of PPS25, the eco-town will not be allowed to have a detrimental impact on flood risk, and will, where possible, aim to reduce flood risk elsewhere. This will be achieved by:
Not allowing any development (unless water compatible) within the floodplain of the River Wey, Deadwater, Oxney Drain and other minor watercourses.
Limiting the surface water discharge from the site to Greenfield runoff rates (including an allowance for climate change) by incorporating control measures, infiltration drainage systems and surface water storage. Therefore, the total discharge and volume of surface water leaving the eco-town will be lower than the existing discharge rate for the development within the eco-town boundary, leading to a reduction in downstream flood risk
Issues & Recommendations
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flood water and can alter the conveyance pathways across the floodplain. By providing floodplain storage on a volume-for-volume, level-for-level basis, this impact can be neutralised.
The most likely area of the site where floodplain storage may be required due to development pressures may be the proposed new town centre. Dependant upon the final floodplain extent from the hydraulic model, a potential solution to releasing future development land may be to provide an element of upstream online or offline flood storage within the Hogmoor Inclosure (Zone 6). Such a feature may provide a valuable wetland habitat, encouraging biodiversity and amenity. However, such an option will require flood defence consent and discussions will need to be completed with the EA at an early stage to establish the relative impacts on ecology, hydrology and surrounding population centres. The importance of the infrastructure surrounding the watercourse necessitates the completion of a more detailed assessment of flood risk.
Recommendations:
watercourse and assess the impacts of climate change on any proposed development.
Any formal restoration proposals for the Oxney Drain would require the EAâ&#x20AC;&#x2122;s Development and Flood Risk and Biodiversity teams to be consulted, in order for a safe and biologically productive scheme to be agreed.
The design of a formal restoration strategy will need to align with the eco-townâ&#x20AC;&#x2122;s aspirations for the Green Infrastructure Strategy. Restoration of the Oxney Drain allows an opportunity to create a dual-use corridor, where the public can not only appreciate the amenity and ecological value that channel restoration brings, but also combine the feature with green transport corridors or economic interest which would benefit from such a feature.
7 BLANK
As part of future works to support the development proposals, hydraulic modelling of the Oxney Drain will have to be undertaken and completed in accordance with a suitable approach agreed with the EA. The aim of such a study will be to define the flood zones associated with the
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7 Water Demand Modelling 7.1 Description 7.1.1
Approach
MoD supply boreholes (source: SEW and Kelda Water Services respectively) A conceptual schematic of the model is presented in Figure 12.
The principal aim of the water demand modelling is to establish whether the available water resources can satisfy the demand of the eco-town, and what combination of water management measures is required to achieve this. PBA has constructed a water demand model which accounts for the usage, supply, recycling and losses of water within a conceptual supply, treatment and distribution system for the eco-town. To conduct the assessment, the following datasets have been used in the water demand model:
Population statistics (current and proposed) for Lindford, Headley, Headley Down and Whitehill Bordon (source: Office for National Statistics)
Rainfall data over a 30 year period from the Bordon rainfall gauge and climate change forecasts (source: UKCIP 09)
Guidance on micro-component water consumption within the home - source: CIRIA WaND (2010), SEW Water Resource Management Plan (2008) and the EA - and current rates of groundwater abstraction from the SEW and
Figure 12 Conceptualisation of water demand model.
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There are three inputs to the model, which represent abstraction, storage and rainfall. There are then three processes accounting for both household and non-household consumption, as well as rainwater harvesting. Outputs from the process include waste water treatment, rainwater treatment and discharge of water to the environment. The model incorporates the potential for a recirculation of green water to be used for non-potable consumption which is linked into the storage element of the model. 7.1.2
Parameters
To ensure a consistent approach towards the water demand modelling, a number of parameters have been fixed for each water supply scenario. Table 7 provides a breakdown and comparison of the figures used for the water demand modelling in both the Halcrow and PBA water cycle studies. Parameter Additional Population New Dwellings Potable Water (Per Capita Consumption) Non-Potable Water (Per Capita Consumption)
Halcrow WCS 14,190 5,500 166 litres per person per day
PBA WCS 11,935 5,300 80 litres per person per day (Target) 45 litres per person per day (Target)
Headroom N/A 10% Employment Water 0.5Ml/d 0.3Ml/d Consumption Occupancy Rate 2.25 2.25 Table 7 Water Demand Modelling Parameters (Halcrow vs PBA).
Full details of the model run parameters as well as the model output is included in Appendix C. 7.1.3
Potable and Non Potable Demand
One of the key components of the water demand model is the consideration of potable and non-potable water usage within domestic properties. The first and most important stage in reducing water consumption should first be focus on changing people’s usage patterns and inclusion of water efficient devices. Measures for achieving reductions in public water consumption habits are detailed in Section 11.3. The second stage should focus on the reuse of water, for example, the capture of waste water from sinks and clothes washing as a source of water toilet flushing. The final stage should focus on the recycling of water. One of the key aims of achieving water neutrality, sustainability targets and reduction in water demand (e.g. Code for Sustainable Homes; PPS1) is the reuse of water for non-potable uses. This is essentially the recycling of ‘grey water’ (e.g. from washing, bathing, kitchen preparations) within the properties or re-use of treated foul water (black and grey water) from the development and redistribution to properties as a lower grade resource (‘green water’), which is used for non-potable usage (e.g. toilet flushing, irrigation). Such measures can significantly reduce the demand for potable water. The in-property fitting of equipment could be in new/ refurbished dwellings and retrofitting of existing dwellings. Distribution of green water is likely to achieve much higher levels of re-use over the long term than in-property equipment enabling grey water recycling
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Other Indoor Use (Clothes Washing, Food Prep, Kitchen Sink) 27%
Outdoor Use 6%
Toilet Flushing 35%
simply due to the ongoing operation and maintenance burden and future refitting of properties by owners. Such systems are more common at a smaller scale (e.g. rainwater harvesting measures and grey water collection within the home for toilet flushing), but at a world wide scale it is uncommon to see such measures at the community/ development level. However, successful large-scale grey water, rainwater and green water collection/ distribution systems have been implemented in locations which have recognised water shortages such as in Sydney, Australia and the City of Clermont in Florida. Using the data provided in Table A4.2 of CIRIA C690 (WaND) (2010), for the purposes of this study nonpotable water uses within the home include:
Toilet Flushing;
Outdoor Use;
Clothes Washing, and;
Dishwashing.
CIRIA C690 WaND (2010) Dishwashing 4% Baths, Showers, Hand Wash Basin 28%
Other Indoor Use (Clothes Washing, Food Prep, Kitchen Sink) 29%
Outdoor Use 6%
Toilet Flushing 26%
Figure 13 demonstrates the typical usage of water within a domestic property based on the total water consumption based on microcomponent figures from CIRIA C690 [WaND] (2010) and SEW Water Resource Management Plan (2008).
South East Water (2008)
Figure 13 Water consumption patterns for a domestic property as proportion of total use [RIGHT] Dishwashing 6%
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Baths, Showers, Hand Wash Basin 33%
By providing both a potable and non potable supply of water to the eco-town there will be measurable reduction in the quantity of groundwater abstraction from the underlying aquifer, which in turn may bring an improvement to the quantity and quality of water supply to sensitive and designated ecological sites in the wider area. In this respect, the eco-town could have a positive affect on surrounding environments, which may have the added benefit of achieving good status in light of the Habitats Directive and WFD. The benefit of using “green water” can be illustrated in Figure 14. Note that the average outdoor use of 6% is assumed to be lost from the measurable cycle, which will vary with the seasons. 7.1.4
Model Verification
As part of the model verification, the model has been made available to the EA to conduct their own review.
7.2 Scenarios 7.2.1
Figure 14 Conceptualisation of the benefits of using green water (based on model output)
Description
The modelling scenarios have been designed to represent conservative scenarios, considering the maximum number of new houses (5,300 new dwellings), climate change impacts, with and without grey water recycling and rainwater harvesting and average water consumption (125 litres per person per day – based on Building Regulations guidelines). In considering a more conservative scenario an element of redundancy can be
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built into the water management cycle. Therefore, there can be a greater degree of confidence in the final water management strategy.
The monthly demand split for the Whitehill Bordon new development (inc. MoD) is shown in Figure 15. This is based on a target household demand of 125 l/h/d and a non household demand of 0.3 Ml/d.
For the purposes of this study the following parameters have been fixed in the water demand model:
7.2.2
Potable and Non Potable Demands
To reduce potable demand, non potable water can be used to supply some micro components in both household and non household units; this study has highlighted toilets, washing machines, dishwashing and outdoor uses as components suitable for non potable use.
0.40
Tim e (M onths ) Potable
Non Potable
Figure 15 Monthly Demand Split (based on Water Demand Model)
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March
February
January
December
November
October
0.00
September
0.20
August
Rainwater Harvesting – modelling scenarios have assumed that only rainwater from the proposed ‘urban centre’ is to be collected as part of a rainwater harvesting system (this represents ~30% of the total area of the development and is based on being able to provide a communal rainwater harvesting system from the new urban centre).
0.60
July
Target potable water demand (MoD retrofit and new build – 80 litres per person per day
June
0.80
May
Micro-components split – as per the SEW Water Resource Management Plan (2008) and EA guidance
1.00
April
1.20
Target personal water consumption – 125 litres per day (MoD retrofit and new build) Volume (Ml/d)
1.40
Schedule
7.2.3
Table 8 provides an overview of the model scenarios which have been considered as part of the water demand modelling. These scenarios have been informed and agreed through liaison the Whitehill Bordon Eco-town Executive Group and Delivery Board, as well as planning liaison and water management representatives of the EA. The purpose of the modelling is to be able to demonstrate that the non potable demand can be supplied by a chosen combination of systems; which therefore reduces the potable demand.
System Rainwater Harvesting Grey Water Green Water
Modelled Scenarios 4 5 6
1
2
3
7
8
average rainfall profile was constructed. This is provided in Figure 19.
7.3 Results A series of charts have been produced as part of the water demand modelling which show the Demand/ Supply balance for a given water supply scenario, where:
0 Ml/d = Water supply can satisfy demand
< 0 Ml/d = Water supply is in DEFICIT and cannot satisfy demand
> 0 Ml/d = Water supply is in SURPLUS and can satisfy demand.
Table 8 Model run schedule
The water demand model has also taken into account the variability in water supply and demand throughout the year. Water consumption tends to peak in the summer months with increased demand for irrigation, which has the added complication of coinciding with periods of low rainfall. To account for the seasonality in consumption and resources, an
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New Balance NewDevelopment DevelopmentAll AllSystems: Systems:Non Non Potable Potable Demand/Supply Demand/Supply Balance
All Systems in Operation (Scenario 1)
[Scenario 1]
With all three systems in operation, the non-potable demand is met with a minimum surplus of approximately 1Ml/d throughout the year as shown in Figure 16.
1.60 1.60
Dual Systems (Scenarios 2, 3 and 4) A communal dual system combining grey water or rainwater with green water is shown to meet the non-potable water demand. However, a communal dual system comprising grey water and rainwater does not meet the non-potable demand throughout the year. Figure 17 shows the monthly supply demand balance for the dual systems.
1.20 1.20
1.40 1.40
1.00 1.00 0.80 0.80 0.60 0.60 0.40 0.40
Tim Timee (Months) (Months) Rain Water RainWater, Water,Grey Grey Water Water & Green Green Water
Figure 16 All Systems Operational
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March March
February February
January January
December December
November November
October October
September September
August August
July July
0.00 0.00
June June
0.20 0.20
April April
If the grey water or rainwater system is combined with the green water system there is a water surplus each month. However, the demand in June and July is not met with the grey water and rainwater systems. For the purposes of the modelling study, the communal green water system has been assumed to serve the new build properties and the existing MoD properties to be retained and renovated as part of the eco-town proposals.
Volume Volume(Ml/d) (Ml/d)
7.3.2
May May
7.3.1
New Development Dual Systems: Non Potable Demand/Supply Balance New Development Dual Systems: Non Potable Demand/Supply Balance [Scenario 2, 3 & 4]
Singular Systems in Operation (Scenarios 5, 6 & 7) A singular system using either grey water or rainwater can not meet the non-potable demand and therefore would require an additional supply of potable water. A singular system using green water (treated black water) would meet demand but is not currently an accepted form of supply (i.e. there needs to be a dilution step before distribution). Figure 18 indicates the monthly supply demand balance for singular systems. 7.3.3
1.00 1.60
1.40 0.80 1.20
Grey water or rainwater can not meet the monthly non-potable demand for the whole year. A green water supply can meet the non-potable demand.
0.80 0.40 0.60
Tim e e(Months) Tim (Months) Grey Water Water & & Rain Rain Water Grey Water
Grey Water & Green Water GreyWater Water&&Green GreenWater Water Rain Rain Water & Green Water
Figure 17 Dual Systems Operational
March
March
February
February
January January
December December
November November
October October
September September
August August
July July
June June
-0.20 -0.20
May May
0.20 0.00 0.00
No System in in Operation (Scenario 8) With no system in place non-potable water can not be used and potable demand can only be reduced by using water saving devices such as dual flush toilets and other measures. These measures can reduce potable demand from around 150 l/h/d to 112 l/h/d. 7.3.4
0.40 0.20
April April
Volume(Ml/d) (Ml/d) Volume
0.60 1.00
Potable Demand If non-potable demand is met by implementing the systems used in the modelling scenarios 1, 3, 4 and 5 then the potable demand is as stated in Figure 15; 1.09 Ml/d for September to May and 1.27 Ml/d for June to August or an annual average of 1.14 ML/d. This is the equivalent to annual average household potable use of 79 l/h/d for the Whitehill Bordon new development (inc. MD).
7.3.5
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New Development Singular Systems: Non Potable Demand/Supply Balance New Development Singular Systems: Non Potable Demand/Supply Balance
The retrofitted houses in Whitehill Bordon could achieve an annual average household potable use of 112 l/h/d.
[Scenario 5, 6 & 7] 0.20
0.80
0.10
0.40
-0.30
-0.60 -0.80 -1.00
-0.40
-0.50
TimTim e (Months) e (Months) WaterGreen Green Water Rain Rain Water GreyGrey Water Water Water
Figure 18 Singular Systems Operational
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March
March
February February
January
January
December
December
November
November
October
September
October
August
-0.40
September
August
July
June
July
June
-0.20
May
-0.20
-0.10
April
0.00
May
April
0.00
0.20 Volume (Ml/d)
However, for comparative purposes a separate model run demonstrates that if dishwashers were connected to the potable water supply, then potable water consumption for the eco-town would increase by 0.08 l/h/d to 87 l/h/d. If this as expressed as a total water consumption for the eco-town then the potable water consumption increases from 1.14 Ml/d to 1.24 Ml/d (an increase of 0.1 Ml/d).
0.60
Volume (Ml/d)
7.3.6 Dishwashing and Water Source There may be some concern amongst residents of using a nonpotable water source for dishwashers. Even with a high quality green water supply, it may prove challenging to change peopleâ&#x20AC;&#x2122;s perception of using recycled water to wash dishes. For the purposes of this the water demand modelling presented here it has been assumed that dishwashers will be connected to the non-potable (green water) supply.
Rainfall Profile - Bordon Rain Gauge
by rolling out either communal or property-scale rainwater harvesting measures to a greater proportion of the eco-town.
120.0
Modelling has indicated that by modelling rainwater harvesting for 30% of the town, an additional 0.55 Ml/d (average) of nonpotable supply would be made available for consumption within the eco-town. With appropriate treatment, rainwater could potentially be used to supply the dishwasher with a â&#x20AC;&#x2DC;top upâ&#x20AC;&#x2122; connection from the potable supply, which would easily offset the increase in water consumption from using only potable water for dishwashing. Issues surrounding maintenance of water treatment infrastructure at a property and communal scale are discussed in more detail in Section 9.
80.0 60.0 40.0 20.0
No ve m be r De ce m be r
ob er ct O
te Se p
Au
gu
m be
r
st
ly Ju
e Ju n
ay M
il Ap r
ar ch M
ry ua Fe br
ua r
y
0.0 Ja n
Rainfall (mm)
100.0
Months Average Rainfall
7.3.7 Climate Change The climate change scenario applied to the rainfall data is based upon the findings from the UKCIP science report, Climate Change Projections. The results for the 50% probability level for the medium emissions scenario for the 2050s show a 0% change in annual mean precipitation for South East England.
CC Rainfall
Figure 19 shows the change applied at the monthly scale. Figure 19 Climate Change Rainfall Profiles
Whilst this causes the per capita potable water consumption to exceed the 80 l/h/d standard set out in Code for Sustainable Homes (Code Level 6), this increase could potentially be offset
The climate change rainfall profiles indicate that Whitehill Bordon will experience dryer summers and wetter winters for the climate change scenario. For the purposes of a monthly average supply demand balance this does not significantly affect the results. However it would become a more important
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factor in sizing a storage facility for the non-potable supply when the combined effects of climate change and a drought year could result in supplies not meeting demand.
No additional treatment or collection facilities – less maintenance.
Drawbacks Retrofit All of the scenarios considered assume that the new build housing, the MoD retrofitted housing and 80% of the civilian housing will be retrofitted with water efficiency devices. With such measures, the total water demand is 112 l/h/d, and without such measures, the total demand (including allowances for system losses) is 173 l/h/d. 7.3.8
7.4 Summary The water demand modelling has identified certain options for the supply of water to the eco-town. Each option has certain benefits and drawbacks in terms of water resources, cost and environmental impacts. 7.4.1
Increased abstractions from SEW boreholes may have detrimental impacts on groundwater resources and nearby European Designated Sites. Potentially, an increase in groundwater abstraction may lead to deterioration in protected habitats and ecology, which would be in breach of the Habitats Directive and WFD.
The EA may not grant an additional increase in groundwater abstraction given the River Wey Catchment CAMS status as ‘No Water Available’.
The increase in water abstraction would be contrary to the principal aim of the eco-town in achieving water neutrality (as defined in the supplementary planning guidance for eco-towns for PPS1). This water supply option does not achieve water neutrality.
No Retrofit, No Green Water Recycling
Benefits
Infrastructure costs would be kept to a minimum (i.e. standard potable water infrastructure and foul water collection)
Retrofit and Green Water Recycling
7.4.2 Benefits
Incorporation of the green water recycling system and retrofitting of existing properties with water efficiency devices would help achieve the eco-town’s principal aim of water neutrality.
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The modelling has demonstrated that the average annual and seasonal demand for potable water for the eco-town falls within the current operating limits of the MoD groundwater abstraction.
There should be no detrimental impacts on European Designated Sites.
Drawbacks
If the public and businesses of Whitehill Bordon are not educated in the benefits of reducing potable water consumption and using recycled water, then there may be significant opposition to a green water solution.
Infrastructure costs associated with the green water distribution network, rainwater collection facilities and treatment of grey and black water will be significantly more than standard development approaches.
The eco-town will require an additional water supply of 1.87 Ml/d, which cannot be sustained by current available supplies of potable water from SEW and the MoD private abstraction. The water demand modelling has demonstrated that green water treatment and supply can reduce the demand for potable water to 1.14 Ml/d, which falls within the current operational abstraction limits of the MoD borehole.
8 BLANK
Furthermore, the modelling has demonstrated that rainwater harvesting can be used as an additional resource to supplement the green water supply throughout the year. The water demand modelling assumes that the green water supply can be sustained by the treatment and redistribution of grey water. Therefore any rainwater which is collected is surplus to requirements. From October to January the available quantum of rainwater is greater than the available quantum of grey water, therefore there is the potential to collect and re-use rainwater during this period.
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8 Drainage Options 8.1 Surface Water This section outlines the proposals for the management of surface water runoff from the development in accordance with National and Regional policy requirements, and best practice guidance. 8.1.1
Policy Requirements and Design Criteria
National Policy in respect of Development and Flood Risk (PPS25) and the SFRA for East Hampshire District Council requires that for development proposals on sites comprising one hectare or above in Flood Zone 1, developers must assess the potential of the site to increase flood risk elsewhere through the addition of hard surfaces and the effect of the new development on surface water runoff. Both policies also recommend that appropriate SuDS measures should be considered as well as the overall layout and form of the development to reduce the overall level of flood risk in the area. As part the consultation process for the completion of the WCS, the EA has set out design criteria in respect of the management of surface water on site. As well as being guided by the specified design criteria, the surface water drainage strategy has also been prepared in line with the Building Regulations 2000, Part H and the best practice guidance document CIRIA C697 â&#x20AC;&#x2DC;The SuDS Manualâ&#x20AC;&#x2122; (2007).
PPS25 outlines guidance on how to allow for the impacts of climate change in drainage design. Table B2, Annex B or PPS25 Table B.2 provides a precautionary response to the uncertainty about climate change impacts on rainfall intensity and recommends that an additional 30% be added to peak rainfall intensity to account for the impacts of climate change. Therefore, in accordance with this guidance, the proposed attenuation provision will be sized to allow for an increase of up to 30% in rainfall intensity. The EA has specified that as part of any design proposals, a SuDS based drainage strategy must be incorporated, which works with natural topography where possible. As a minimum, the following design criteria need to be satisfied:
Surface water attenuation will have to contain the surface water runoff from the 1 in 100 year (with an additional 30% for climate change) critical duration rainfall event
Discharge from surface water attenuation will have to be restricted to the Greenfield runoff rates, and may need to include for the provision of a complex control to ensure there is no increase in discharge from the site for low, and higher magnitude rainfall events.
Any proposed infiltration areas/ measures will require insitu infiltration testing, and the base of any such measures will have to be at least 1m above the seasonal maximum
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water table â&#x20AC;&#x201C; this will require monitoring to establish exactly what the seasonal maximum water table is.
Surface water attenuation measures will have to be located outside the 1% annual probability (1 in 100 year) with climate change floodplain extent.
The surface water drainage strategy will have to consider overland flow routing through the development site in exceedance events.
The surface water drainage network will have to be designed to ensure no above ground flooding for the 1 in 30 year event.
For the 1 in 100 year event, any above ground flooding from the surface water drainage network must be contained on site.
drainage modelling, an outline assessment of the surface water attenuation requirements for the eco-town proposals has been completed, based upon analysis of drainage catchments, impermeable areas for each Masterplan designation and calculation of Greenfield Runoff Rates. 8.1.2
In its current form, the draft masterplan does not provide sufficient detail to undertake a detailed drainage assessment. A detailed drainage strategy would require development plot layouts, site topographical survey and visual inspection of existing drainage infrastructure. Likewise, an assessment of underlying ground condition would have to be undertaken to confirm the suitability of the site for infiltration drainage measures, for the disposal of surface water. Such an assessment falls outside of the scope of this study. However, using industry standard hydrological methods and
Existing Drainage
As detailed in the previous sections, the site currently discharges via a system of collector channels, gullies and interceptors, which connect to an underground piped drainage system. Flows from the western and northern parts of the site (Zones 1, 2, & 6) are discharged into the Oxney Drain, whereas the Quebec and Trenchard Barracks (Zone 3) discharge into the River Wey. 8.1.3
Infiltration to Groundwater
Due to the nature of the underlying geology for the site it is anticipated that the site will be suitable for infiltration drainage. The FEH CD-ROM (version 3) classifies the site as having a very low Standard Percentage Runoff (SPR) value, which indicates that the underlying ground conditions offer significant permeability. However, before any infiltration drainage proposals can be proposed detailed ground investigations need to take place at specific locations across the site to confirm suitability and variation in the rate of infiltration offered by the permeable ground conditions as well as locating any areas of the site
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where there is a high risk of contaminant mobilisation through leaching, which may pollute the aquifer. Such information is critical to the design of any surface water drainage system, as by maximising infiltration the total land take required for surface water attenuation can be reduced. 8.1.4
Greenfield Runoff Rates
Initial calculations have been completed to confirm the existing Greenfield runoff rate for a range return periods In line with the guidelines set out within the Interim Code of Practice for Sustainable Drainage System (National SuDS Working Group, 2004), the Greenfield runoff rates for the site have been calculated using the Interim Code of Practice for SuDS (ICP SuDS) hydrological methodology. The rates in litres per second per hectare (l/s/ha) are as follows:
Average Annual Rate (QBAR): 0.5 l/s/ha
1 in 30 Year:
1.2 l/s/ha
1 in 100 Year:
1.6l /s/ha
8.1.5
Possible Surface Water Drainage Regime
A preliminary indication of the likely surface water drainage regime has been considered for the development proposals and adheres to the specific requirements of the EA.
As outlined in consultation with the EA, at this stage the intention is to drain the eco-town site by both a conventional piped surface water drainage system and a network of swales/ conveyance corridors, which will eventually discharge into the Oxney Drain, The River Wey and by soakaway drainage to the underlying aquifer. Appropriate flow control and attenuation measures will be provided in order to ensure the discharge rates from the site to each watercourse do not exceed the Greenfield runoff rate for the site. The piped drainage system for the development proposals will have to be designed in accordance with Sewers for Adoption 6th Edition, to enable adoption of the system by Thames Water or another sewerage undertaker. It will be necessary to attenuate flows from the proposed development to the Greenfield Runoff rate, for up to and including the 1 in 100 year rainfall event with an allowance for a 30% increase in rainfall intensity due to the potential impact of climate change to ensure there is no increase in flood risk to the proposed development or downstream. In order to attenuate flows it will be necessary to provide appropriate storage features as part of the proposed surface water drainage system. A full assessment of the attenuation requirements and outline sizing of an appropriate drainage feature is provided in the following section.
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At present there is not sufficient information available to confirm the current operation, capacity and design standard of the MoD surface water drainage system. Although records of the drainage infrastructure have been provided, which has enabled delineation of the existing drainage catchments within the MoD site, this data provides no specific details. Therefore, it is not appropriate to state whether the existing system can be retained, replaced or upgraded to meet national standards on sewerage design. It is recommended that as part of further investigation, a hydraulic modelling study/ assessment of the existing MoD drainage infrastructure is completed to confirm this. Such a study may offer substantial cost savings in the long-term, by identifying those sections of the network which are suitable/ inappropriate and focussing investment rather than applying a blanket approach of sewerage replacement. 8.1.6
proposals up to the 1 in 100 year rainfall event (including a 30% allowance to account for climate change), approximately 130,000m続 of storage will be required for the whole site. This estimate does not take into account infiltration of surface water to groundwater. Whilst surface water attenuation can be accommodated within the development in a number of ways (both above and below ground) for the purposes of this assessment an attenuation basin for each drainage catchment has been assumed to provide an indication of the anticipated land take required to accommodate the surface water attenuation. Drawing 24763/001/007 in Appendix A, shows the indicative land take required for each surface water attenuation feature based on the storage estimate outlined in Table 9 and the assumptions outlined below:
A depth of storage of 1.5m
0.5m freeboard is included to reduce any residual risk to the development for rainfall events in excess of the 1 in 100 year return period, or should the outfall from the ponds become blocked
1 in 5 side slopes to accord with the RoSPA guidelines (Safety at Inland Water Sites), which requires gently sloping side slopes
Surface Water Attenuation
A preliminary assessment of the total volume of surface water storage required to provide adequate attenuation has been completed for each drainage catchment defined as part of the morphometric analysis (as described in Section 5). Accordingly, a total of 13 drainage catchments have been defined based upon the analysis of the digital terrain data and the draft masterplan designations. A preliminary assessment indicates that to provide attenuation of the surface water runoff from all of the new development
It should be noted that the footprint of the surface water attenuation features is indicative at this stage and based on a
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number of variables. It is anticipated that the estimated land take will be refined as a more detailed assessment is completed and the exact size, shape, number and locations of attenuation features will be defined. Furthermore, the current draft masterplan shows a number of locations across the site where infiltration drainage measures can be incorporated. Large scale infiltration measures can be combined with public open space, sports pitches of educational establishments and parkland. Such measures can offer the installation of large-scale infiltration blankets, which can be used for the disposal of surface water to groundwater (and hence a method of aquifer recharge), but can also serve dual function, such as maintenance of a well-drained recreational area. The image in Figure 20 shows a PBA-designed scheme where an attenuation basin (with permeable base) and an infiltration blanket arrangement under playing fields has been constructed. By combining such measures with public open space, the overall land take required for attenuation features can be significantly reduced. The design of such measures will have to align with the eco-townâ&#x20AC;&#x2122;s aspirations covered in the Green Infrastructure strategy. Such dual-functionality can bring benefits to the community but has to be considered against issues of cost and development facilities.
DRY CONDITIONS
WET CONDITIONS Figure 20 Attenuation Basin and Infiltration blanket arrangement Angmering, West Sussex
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As reported in the previous chapters, the ground conditions and underlying geology at the site and the wider area is indicated to offer sufficient permeability to allow for infiltration drainage solutions. As well as infiltration blankets, the surface water drainage system could be designed to allow for infiltration throughout the conveyance routes. Drainage Catchment
Required Storage Volume (m³)* (m³)*
NO INFILTRATION Area (m²)* (m²)*
WITH INFILTRATION Area (m²)* (m²)*
W1
14400
11400
10900
W2
31700
23800
22400
W3
18400
14300
13800
W4
3000
2900
2800
W5
11200
9000
8600
W6
900
1100
1100
W7
4500
4100
4000
M1
15900
12500
11900
M2
4200
3800
3600
E1
6500
5600
5300
E2
7900
6600
6300
E3
10000
8200
7900
Table 9 Outline estimate of surface water storage volume and indicative land take for each drainage catchment *Volume rounded to nearest 100m³/ Area rounded to nearest 100m²
For example, runoff from open space and green corridors could be collected by infiltration swales, which would not only convey the flow to a downstream attenuation facility, but would allow for a proportion of the flow to discharge to the underlying aquifer. These measures can further reduce the land take required for surface water attenuation, but can only be designed following the completion of on-site ground investigation (to identify contamination) and soakaway testing. Other aspects which should be considered as part of a more detailed design include:
Within dry attenuation facilities, an allowance of 10% by volume should be incorporated within the design for dilapidation.
A 5m buffer strip surrounding the surface water attenuation facility should be allowed for to provide access for future maintenance.
Surface water attenuation features must be located outside the extent of the 1% annual probability (1 in 100 year) with climate change flood extent, and outside the extent of any maintenance strip associated with the watercourse (typically, this is 8m from top of bank).
Consideration of the connection to the receiving watercourse (e.g. level of invert, outlet design, complex controls, flapped outfalls).
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8.1.7
Pollution Control
Pollution control measures should also be included to minimise the risk of contamination or pollution entering the receiving watercourses and groundwater. In this case the River Wey, the Oxney Drain and the underlying aquifer at the MoD site. The drainage system should therefore be designed to comply with the requirements of the SuDS treatment train as laid out by CIRIA 697 â&#x20AC;&#x2DC;The SuDS Manualâ&#x20AC;&#x2122;. According to CIRIA 697, runoff from residential areas is likely to require two stages of treatment. The provision of proprietary oil/silt and debris traps as part of the conventional drainage system is appropriate as the first stage of treatment. Retention in attenuation features, vegetative filtering or infiltration should provide an appropriate second stage of treatment As part of the detailed design process reed beds or wetlands may also be included within the proposals to provide an additional element of pollutant removal. 8.1.8
Overland Flows
For storm events with a return period greater than the design standard for the proposed drainage network it will be necessary to consider how overland flows will be routed from each parcel of the eco-town to the relevant surface water attenuation feature (e.g. pond, basin, swale)
Overland flow routing should be included within the development proposals through the use of the primary infrastructure and highways, or through open spaces and the use of swales. The design of on site roads and development plots will need to take into consideration overland flow routing to ensure that the proposed roads do not provide a constraint to flow routing, causing flood risk to the development parcels. Due to the proposed retention of the existing drainage ditches across the MoD site (as indicated in the Masterplan), it is likely that overland flow from areas of landscaping, gardens or roads can be conveyed to the Oxney Drain and associated tributaries. For example, at the western boundary of the site there are proposals to restore/ construct a watercourse which could potentially receive inflows from drainage catchments W1, W3 and W4. 8.1.9
Maintenance and Control
Currently, stakeholders are keen to see the sewerage infrastructure maintained by an inset water management company, although it is also a possibility that the local sewerage undertaker (Thames Water) will take ownership and maintenance of sewerage assets. However, the design of the final system should still aim to be compliant with Sewers for Adoption 6th Edition or any later amendments.
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Provision for the adoption of the surface water attenuation facilities would either need to be arranged with the local authority or under a management agreement with an inset water company.
rainwater and surface water runoff. As explained in Section 7, a green water supply could not be reliant upon rainwater, but could effectively be ‘topped-up’ by the rainwater contribution and also offer a form of dilution or blending.
It is possible that under the Flood & Water Management Act, Hampshire County Council could adopt SuDS features such as attenuation features under their responsibility as the SuDS approving body for the region, providing that the features meet their approval criteria. However, if proposals for an inset water management company are approved, then it is likely such a responsibility will be transferred.
8.2 Green Infrastructure Infrastructure
8.1.10
Rainwater Collection
If the surface water drainage system is designed appropriately with the correct SuDS treatment trains (as per CIRIA C697), then there is the potential to link the system directly to a site rainwater collection facility. For example, swales and attenuation facilities could be used to provide an initial stage of water treatment, allowing sediment to settle out of suspension. By working with natural methods of water treatment the total energy and resources required for treatment of surface water at a green water treatment facility can be kept to a minimum and potentially limited to just disinfection. It is unlikely that such a collection system could be rolled out on a site-wide scale, but at the urban centre where there is likely to be a larger proportion of impermeable surfaces generating more surface water runoff, there may be the potential to collect
8.2.1
Function
The implementation of a robust plan for Green Infrastructure (GI) is critical to the success of the eco-town. The key component of GI is ‘dual function’. GI provides reductions in the Urban Heat Island (UHI) effect, reduced flood risk, improvements in air quality, economic growth, improved movement of people, improvements to local ecology, investment and enhancement of the economy.
UHI – GI can ameliorate the warming effects of climate change and UHI. GI can reduce higher urban temperatures through evapotranspiration, direct shading and conversion of solar radiation to latent heat.
Flood Risk – GI can reduce flood risk by promoting the infiltration of surface water to ground, increasing the ‘lag time’ between rainfall and flow peak flow response, and reducing the volume of runoff from a site through interception
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Air Quality – Vegetated areas can increase absorption of gaseous pollutants and interception of particles and increased levels of transpiration can reduce the formation of ozone.
Economy – GI can enhance an area’s reputation and are particularly popular for attracting high value industries, new businesses and entrepreneurs. Building next to GI can have a positive effect on land value
Wildlife – GI and in particular green and blue corridors can encourage the movement of wildlife and provide space for a particular ecological niche to establish and create a thriving habitat.
Improved Health and Quality of Life – By incorporating green space into an urban setting it can encourage people to exercise, which brings obvious health benefits. The combined effects of all of the benefit that GI brings can also lead to an overall improvement in quality of life,
8.2.2
Green Infrastructure Strategy
As part of the eco-town proposals Halcrow were commissioned to complete a GI Strategy in support of the development. As part of the GI Strategy, Halcrow has consulted with local stakeholders to support the GI planning process and draws upon consultation carried out as part of the Aecom Masterplanning work for the eco-town.
Following the GI Stakeholder Workshop on February 17th 2011, there were a number of issues raised by local stakeholders concerning the location, extent and form of GI. One of the key aspects from the GI workshop was to ensure the protection of European Designated Sites. The workshop notes report: ‘The highest priority is to ensure the protection of European Sites that surround the eco-town by providing Suitable Alternative Natural Greenspace (SANGs), buffers to dissuade people from going onto the European sites (e.g. dense belts of trees) and providing links for wildlife (not people) between the protected sites’. From a water resources perspective, the GI workshop also reported St Philips Barracks as a location where there are known drainage issues associated with the culverted section of the Oxney Drain. Stakeholders have stated that as part of the GI works, there is potential to improve this watercourse through deculverting. This is something that has already been identified as a potential area of improvement by the WCS, and as part of any future development proposals a restoration strategy would be proposed for the Oxney Drain. The Oxney Drain has potential for dual function as a green corridor, providing transport linkages, pedestrian movements, public amenity and a key wildlife connection to Oxney Moss (north of the site). Channel restoration measures for this watercourse would involve deculverting, removal of the
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concrete sections of watercourse, bank reprofiling, reinstatement of the natural bed gradient and meanders (where possible). The focus of the restoration proposals should be on removing existing channel constrictions, introducing variability within the watercourse (encouraging variation in morphology can help in the development of ecological niches) and where possible (i.e. where there isn't an increase in flood risk) create a functional and successful riparian habitat. The form and function of such a scheme cannot be considered in detail until the baseline fluvial flood risk is understood and how this might change as a result of the masterplan. Any proposals for river restoration would also have to be modelled to assess flood risk impacts. Local stakeholders are also keen to see that the Deadwater Valley LNR is not treated as a boundary separating Whitehill Bordon from Lindford. Access improvements to the valley should be considered to draw people toward the LNR, and alleviate some of the pressure on the European Designated Sites. However, improved access and increased footfall will need to be balanced against meeting requirements of the Habitats Directive and WFD owing to the species richness and moderate water quality. Although it is appreciated that GI must be considered in terms of its dual function, there were a number of stakeholders who were keen to see GI features serving a single function as a wildlife corridor (i.e., no pedestrian linkage, no link up with
sustainable drainage features). Such measures may be difficult to accommodate, but given an appropriate degree of consideration, wildlife corridors can be designed to serve a dual function without detrimental effects to ecology. Halcrow have used the stakeholder inputs from the workshop to refine the draft masterplan. In consultation with Halcrow, it has been determined that there are no major conflicts of interest in terms of the proposed GI and the surface water drainage proposals. However, at this stage of the development the surface water drainage strategy is in its early outline phase and requires ground investigation studies, site wide topographical survey and more details on the development plot layouts before the sizing and arrangement of drainage features (e.g. attenuation facilities, swales, infiltration trenches/ basins, piped drainage systems) can be determined. 8.2.3
Development
Where possible and appropriate, it should be an aim of any future development of the eco-town to merge the green corridors and public open space with the surface water drainage infrastructure as part of the Green Infrastructure strategy. For example, the draft masterplan demonstrates a number of green corridors bisecting the development, which can be used for pedestrian and wildlife movements, but such corridors can also be merged with conveyance routes and storage areas comprising the surface water drainage system. Such measures would have the added benefit of creating a space for amenity and inward investment.
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8.3 Foul Sewerage 8.3.1
Existing Issues
The major issues facing the existing foul water drainage system at the MoD site are:
Cross connections and seepage of surface water into the foul drainage system
Capacity issues within the foul water drainage network itself – there is no information on current design standards and operation of the MoD foul water drainage network.
Capacity issues at Bordon STW – e.g. flooding/ backing up of foul water within the toilets at Trenchard barracks (Zone 3).
These issues are described in greater detail in Section 5. TW has not reported any capacity, condition or flooding issues associated with their existing foul sewerage infrastructure within the locality. The only issue which has been raised is the limited capacity of Bordon STW. Therefore, it has been assumed that all development within the eco-town boundary that is already connected to the TW foul water drainage network will continue to drain via the network.
8.3.2
Compliance
Owing to the current management operations at the site under the Project Aquatrine PFI, and the uncertainties regarding future asset ownership and maintenance, it is likely that existing sewerage infrastructure within the MoD site may have to be either upgraded or replaced. For TW (the local sewerage undertaker), or an appointed inset water management company to adopt any existing sewerage infrastructure, it would have to be proven that the existing drainage network met the current adoption criteria of Sewers for Adoption (6th Edition). One of the key issues may be system capacity. It is unlikely that the entire MoD foul sewerage network meets the Sewers for Adoption criteria. To confirm existing capacities and compliance with Sewers for Adoption would require the construction of a hydraulic model representing the existing MoD foul water drainage system. Furthermore, issues with cross connection and seepage of surface water into the foul water drainage network are likely, and is supported by stakeholder claims of flooding of the foul water network and “backing of water in the toilets at Trenchard barracks during periods of heavy rainfall. Such issues will need to be resolved before either TW, or an appointed inset water management company, are in a position to adopt.
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8.3.3
Potential Loadings
The total volume of foul water being generated from the development proposals has been calculated using the upper estimate of 5,300 dwellings, and the area of the site which comprises commercial and educational activities. According to the guidance within Sewers for Adoption (6th Edition) the following flow rates (shown as litres per second per hectare – l/s/ha) should be used when designing a foul water drainage system:
Commercial – dry industry (e.g. offices, retail)– 0.5 l/s/ha
Commercial – wet industry (e.g. food production) – 1 l/s/ha
Commercial – unknown – 0.75 l/s/ha – used when commercial split is not known
Domestic – based on the dry weather flow, which is calculated using BSEN 752-4
For the purposes of generating an outline figure for foul water loadings the commercial, industry and education draft masterplan designations have been aggregated together, and an average rate of 0.75 l/s/ha has been applied. The total coverage of these designations is approximately 70ha. This equates to a peak foul water flow rate of 52 l/s from commercial, industrial and educational sources.
Domestic peak flow rate has been based on the standard methodology in Sewers for Adoption (6th Edition) assuming six times the dry weather flow rate. Accordingly, based upon a maximum number of 5,300 dwellings, an occupancy rate of 2.25 and a daily output of 200 l/person/day, the peak flow rate from residential dwellings is anticipated to be 165 l/s. The total estimated loading at the sewage works will therefore be 217 l/s and a daily flow of 3.1Ml. This is about 1Ml/day more than the calculated obstruction and reflects the different nature of the calculation method and historic allowances for infiltration. These numbers provide an indication of the likely peak foul water flow rates and the overall capacity requirements. The existing consent for Bordon STW has a daily flow limit of 8.79 m³/day but this includes discharges from areas outside the Whitehill Bordon Eco-town area. (Furthermore, the water demand modelling has indicated that if the development incorporates rainwater harvesting, grey water recycling and green water distribution to satisfy the demand to supply water for non-potable uses, then foul water production may reduce by approximately 35%). Whilst the total volume of water to be treated will remain, the volume discharged will be significantly reduced. 8.3.4
Solutions
A review of the general topography across the site and the current location of the sewerage network as shown on the MoD’s records indicate that the whole site can continue to drain
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via a gravity drainage solution to the MoD foul water pumping station to the north west of Louisburg Barracks (Zone 2). This report has already outlined the historic purpose of the pumping station site as the MoD sewage works. The works currently receives foul flows from the whole of the MoD site via a gravity drainage system, before pumping via a rising main to the Bordon STW to the east of the site. There are potential options to alleviate the capacity concerns at the Bordon STW, which include:
Installation of a modern sewage treatment works at the site of the MoD pumping station, which uses innovative, low energy sewage treatment, and;
An anaerobic digestion facility to treat the sludge and avoid transport to Farnham.
Further information regarding the possible design of the new works and upgrade to Bordon STW is included in Section 9. In order to confirm the viability of this connection, it will be necessary to obtain further details regarding the existing topography of the site and the development proposals. A key consideration will be the crossings of the Oxney Drain and other drainage ditches running through the central (Zone 6) and northern (Zone 1 & 2) parts of the site along with any third party land issues.
At present there is not sufficient information available to confirm the current operation, capacity and design standard of the MoD foul water drainage system. Although records of the drainage infrastructure have been provided, which has enabled delineation of the existing drainage catchments within the MoD site, this data provides no specific details. Therefore, it is not appropriate to state whether the existing system can be retained, or will need replacement or upgrade to meet national standards on sewerage design. It is recommended that as part of further investigation, a hydraulic modelling study/ assessment of the existing MoD drainage infrastructure is completed to confirm this. Such a study may offer substantial cost savings in the long-term, by identifying those sections of the network which are suitable/ inappropriate and focussing investment rather than applying a blanket approach of sewerage replacement.
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9 Supply & Treatment 9.1 Water Supply The Water Demand Modelling has demonstrated that in order to sustain the proposed population and commercial activities of the eco-town an additional 1.87 Ml/day of water will need to be made available. Whilst SEW has indicated that there is sufficient headroom within the Resource Management Zone (RMZ 5) to sustain the forecasted increase in water consumption from the eco-town, the actual water available is currently restricted by the EA Abstraction Consents on the local SEW boreholes at Oakhanger and Headley Park. Any increase in groundwater abstraction will be difficult to justify given the proximity of the SEW boreholes to groundwater fed European Designated Sites, as well as the current status of the River Wey catchment in the CAMS as “No Water Available”. Furthermore, any increases in water abstraction would mean the eco-town proposals would not be achieving ‘Water Neutrality’, which is a critical element of the supplementary guidance note for PPS1 concerning eco-towns. However the water demand modelling has also demonstrated that by employing a suite of water efficiency measures, grey water recycling and green water distribution, the total demand for potable water can be reduced to 1.14 Ml/day. Whilst the SEW boreholes will not be able to sustain this demand, the MoD borehole could continue to be used as a potable water supply to sustain the new build and retrofitted properties of the
eco-town. The estimated potable water demand is well within the current groundwater abstraction from the St Lucia Pumphouse, which lies between 0.6 and 1.5 Ml/day. Continuation of the existing abstraction would maintain the status quo in terms of the current local hydrogeological regime, which should also ensure ‘no detrimental impact’ on the groundwater resource, populations and surrounding habitats, to achieve water neutrality – a crucial component of any ecotown.
9.2 Water Reuse In order to assist in promoting the aspiration for the eco-town to be ‘water neutral’ (i.e. no more water leaving the site postdevelopment than there was pre-development), it will be imperative to create a technically viable and cost effective system for the re-use of water on the site as a secondary supply. We may refer to this secondary supply as ‘green water’. It is technically feasible in all new development, and in some existing areas as a ‘retro-fit’ procedure, to install dual pipework into housing to enable residents to take advantage of this secondary, ‘green water’ system, and thus have more than the 80l/h/d of potable water at their disposal without compromising the latter supply.
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Scale
Single Building 1) Domestic 2) Commercial 3) Industrial
Community/ Neighbourhood
No of buildings
1 House Office Factory
10 Predominantly housing
Development
1,000 Predominantly housing, some social building e.g. 1arySchool, or mixed (shops and offices)
Quarter/ Urban Extension/ ecotown
5,000+ Predominantly housing, but could include industrial estate, local hospital, 2ndry school etc
Scenario 1 No ‘Risk’ Water ‘Business as Usual’ (BaU) Town main in, waste water out to WWTW Some retro-fitting to be undertaken.
BaU As above
BaU As above
BaU As above
Scenario 2 Medium ‘Risk’ Water Mixed solutions. Town Main water in, RWH, Demand Management measures
Scenario 3 High ‘Risk’ Water Off Town main. Local source, Full recycling (grey to green water) + RWH. Live within resources available
Possible local stream source with backup Town Main Mixed ‘community solutions – sharing of RWH, water reuse
Off Town main. As above
Local source, backup Town Main. (borehole/ small reservoir). Local WWTW to recycle ‘green’ water. Will require licensed discharge point
Off Town main. May install own main if adequate resource available, own WWTW plus green water recycling. Will require licensed discharge point for effluent.
As above. Possible reuse of green water for industrial purposes
As above.
Table 10 Water scenarios at different scales and illustrating increasing degree of ‘risk’.
There are several options which may be considered to achieve a supply of ‘green water’:
Rainwater capture and use
Storm Water capture (SuDS) and use
‘Grey’ water separately collected and treated for reuse
‘Black water’ (total sewage) to be treated for re-use
Additionally there is the option of scale to be considered. Different
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solutions will be necessary to meet different degrees of scale, which will also be influenced by the rate of ‘roll-out’ of a development programme. Table 10 sets out a number of possible options for water cycle delivery from a single building to a whole new urban quarter or eco-town, and which would contribute to meeting the constraints of water neutrality. The term ‘risk’ in this context relates to security of supply.
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The concept of managed risk will always be present with a water services system. Table 10 pushes the boundaries further than under normal service circumstances, but given the assets already in place (boreholes, water treatment works, distribution networks and sewage treatment works), a strong case could be made for a town water company based on 5,300 new homes and part of the existing customer base which was largely independent of the existing incumbents. Table 11 displays the potential water technologies available for an eco-town such as Whitehill Bordon for the economising of potable water use in building and community scale developments.
Option Reservoir and mains network distribution (Business as Usual, (BaU) Centralised. Centralised. Water Meters [Centralised Centralised, Centralised but all supplies will require metering.] Local sourcing of water (e.g. borehole) Centralised or Decentralised.
‘2nd’ distribution pipe (3rd pipeAustralia) Centralised or Decentralised.
Water Supply Options Technical Details Opportunities Water Supply Services (Potable) Full control and responsibility by Total revenue to water water company. Regulated by company. Ofwat. Almost 100% security of supply for customer. In line, installed and owned by Customer is charged water company. Can be directly according to use. monitored by customer if mounted/ accessed internally Water may require treatment to Could reduce or increase DWI standards. charges to customer Very stable source of supply. depending on treatment required. Lower transportation costs hence more energy efficient. Water Supply Services (Non(Non-Potable [‘green’]) All buildings, including industrial Customer charges are connected with secondary supply lower for green water for ‘lower grade use’. which may account for up Can be comprehensive water to 50% of use. Relatively company service or independent easy to install on new supply.(Centralised or build, less so on retrofit. decentralised).
Constraints Little flexibility. Expensive to operate. Large asset base which may leak incurring losses. RV system (i.e. no meter) may be financially advantageous to larger water users May require significant capital investment by water company or developer. Maintenance costs. Security of supply to customer not 100%.
Some extra costs in dual plumbing, paid for by developer.
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Water Supply Options Technical Details Opportunities Constraints All Options below can be Centralised or Decentralised or used in combination Rainwater Harvesting. Most likely Both at single building and at A good grade of secondary Dependant on rainfall events. to be Decentralised. community levels. Water stored ‘green’ water for non-potable May have to fall back on water Decentralised. and drawn as required. uses. Costs are relatively low – company mains system for security Minimum maintenance. individual homes pay of supply. installation costs and very low running costs. Generally accepted by the public. Grey water recycling to provide A variety of technical solutions: ‘Green’ water a more Needs to be clearly identified as ‘green’ water. marketable/ acceptable ‘secondary’ supply to avoid cross Most likely to be Decentralised. concept to public. connections. Decentralised. Simple filtration Mechanical through flow. Low or Easy to install, Removes many Does not significantly address (‘box’) Decentralised. Decentralised. no energy demand. Minimum solids. bacteriological parameters. maintenance. MBR (Membrane Bio-reactors). Mechanical/ electrical. Complex Produces a very high grade of Complex and costly installation. Decentralised and relatively energy intensive. ‘green’ water. Able to Rejected effluent stream will require A level of specialised consistently meet tight quality storage and disposal. maintenance required. parameters. Reed Bed (RB) technologies. Simple, using physical and Largely passive. Low energy Regular maintenance important with Includes Vertical and Horizontal botanical filter media variously. use. understanding of requirements of Flow RBs and other forms of small Low energy use. Uses natural processes. both hydrological and botanical scale engineered wetlands aspects. (including GROW). Water quality, if re-used, may vary Could be either Centralised (small (e.g. seasonally). scale) or Decentralised. Decentralised. Option
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Option Surface water sewers, roadside gullies etc (i.e. the ‘traditional’ (BaU) solution. [Centralised] Centralised]
Sustainable Drainage systems (SuDS are comprised of elements. A number of bodies may have responsibility for adopting SuDS. At present, it is unknown who would be the adopting body. Likely to be [Centralised]. [Centralised] Porous paving. As part of SuDS. [Decentralised] Decentralised] Swale As part of SuDS. [Centralised]
Detention Pond As part of SuDS. [Centralised] Green Roofs [Extensive or Intensive] Extensive: substrate designed to retain water in medium and through succulent plants. [Decentralised] Decentralised]
Surface Water Drainage Technical Details Opportunities Network operated by water Existing (known) network company. Storm water drains, receives some maintenance. without restraint, to natural water courses, often causing pollution. Great uncertainty as to who has Land set aside to accept and responsibility for SuDS systems. manage storm water events sustainably.
Hard surfaces (e.g. car parks) laid with porous paving (rather than ‘blacktop’). Shallow ditch-like feature running parallel to highways to accept run-off and filter water before infiltration. Low lying area designed to temporarily hold a calculated volume of water before allowing slow release. Establishment of plants and substrates on the roofs of new buildings with a view to store surplus water for attenuated release.
Water is adsorbed by ground through percolation. Virtually no maintenance. Effective form of drainage for moderate rainfall. Low maintenance. Can be used as amenity area when dry. Control against flash flooding. Assists in the management of storm water through retention and slow release. Can also provide wild life habitat, and visual interest.
Constraints Sewers often operating at or near capacity before new development. This can lead to surcharging of sewers, Customer suffers.
Can (apart from Green Roofs – see below) take considerable amounts of land set aside purely for water flow management.
May flood when ground becomes supersaturated. May not have adequate storage capacity for prolonged rainfall event. Could accumulate long term hydrocarbon pollution. Takes space (and hence profits) from potential development.
Building needs to be designed for extra weight on roof.
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Option
Technical Details
Waste Water Treatment Works. [Centralised] Centralised] Activated Sludge, trickle filters [Centralised] Centralised]
Various:
MBR (Membrane Bio-reactors). [Decentralised] Decentralised]
Rotating Biological Contactor (RBC). [Decentralised] Decentralised]
Waste Water Treatment Opportunities
‘Modern traditional’ method of sewage treatment. Largely automatic. Mechanical/ electrical. Complex and relatively energy intensive.. Specialised maintenance required. Used widely for small communities. Low energy, low maintenance. Effective in reduction of main parameters of water quality.
Constraints
Relatively consistent effluent quality and which can be controlled. Economies of scale. Produces a very high grade of ‘green’ water. Able to consistently meet tight quality parameters.
High energy use in moving water and aeration systems. Large land requirement. Requires water course of sufficient capacity to dilute and buffer effluent stream. Complex and costly installation. Any rejected/unsuitable effluent stream will require separate management/treatment.
Small land take, can be discretely housed. Energy efficient.
Limited number of connections per unit.
‘Living Machine’ type technology (as in ‘Green Water Treatment Plant’). [Decentralised] Decentralised]
Hybrid between activated sludge and hydroponic system. Medium maintenance and energy costs.
Relatively effective for water quality, visually and educationally excellent. Creates a natural amenity environment.
Requires a greenhouse (land) and (some) specialised training to operate.
Reed Bed systems [various] (especially for tertiary treatment, as above). Likely to be Decentralised
Often used as ‘polishers’ before effluent enters natural water course.
See above for various benefits.
Land take varies from large scale to small scale engineered wetlands.
Table 11
Water Options (Source: ‘Ashford’s Integrated Alternatives’ (AIA) consortium led by Centre for Water Systems, University of Exeter, 2011)
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9.2.1
would also be described as ‘green water’ dependant on meeting the above minimum standards
Criteria for ‘Green Water’
A definition of ‘Green Water’: Green water is a generic description for water which:
Has been treated to a grade suitable for provision as a nonpotable, secondary supply, usually, but not exclusively, in parallel with a potable supply, for industrial, residential or public use (examples might include toilet flushing, horticultural/irrigation purposes, irrigation of sports pitches, public area cleansing, sewer jetting, laundries, industrial processes or washing, heating/cooling functions etc)
Has the following characteristics: a) Conforms to biological criteria for tertiary treatment, typically <10mg/l BOD (Biological Oxygen Demand), <10mg/l Suspended Solids and < 5mg/l Ammonia, lacks turbidity <2NTU (Nephelometric Turbidity Units), is pathogen free < 10cfu (colony forming units)/100ml) b) Should be clearly identified as a separate supply, not for human consumption, by the use of a green tinged vegetable dye at a specified dilution (1:20,000) c)
Rainwater, treated ‘grey’ water, storm run-off water and raw water (e.g. borehole derived) from other sources,
‘Green Water’ should be distributed via a networked system of pipework which is of a distinct BS green standard colour and identifiable by a continuous black line along opposite sides of the diameter of the pipe or similar configuration readily identifiable and indexed in the building trade, and which through such identification cannot accidentally be cross connected with a potable system. There is continued discussion as to whether such green water pipework should be of nonstandard diameters to actively frustrate cross connection with the potable water system. 9.2.2
Delivery of ‘Green Water’ options
Assuming that all new homes in the Whitehill Bordon Eco-town are to be built to meet CSH (Code for Sustainable Homes) Levels 5 or 6 where the target for potable water consumption is 80l/h/d, and that it is commonly accepted that toilet flushing plus garden irrigation may consume around 40l/h/d (on an average estimate), then it is clear that there will be adequate water to meet the recycled requirement. It is therefore also clear that all new homes should be dualplumbed from the outset in order to accommodate the secondary supply as and when it becomes available. Additionally, as the summary of options shows, there is an option (probably related to scale) for dual plumbing the
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wastewater stream into a ‘black’ and ‘grey’ network, where ‘black’ water refers to the total sewage load, whereas the term ‘grey’ water is applied only to water collected separately from baths, showers, sinks [and debatably washing machines]. Kitchen sink waste is not to be included in the ‘grey’ water category due to the prevalence of fats, oils and greases (FOGs). ‘Grey’ water, due to its lighter biological and chemical loading may be viably treated at a more local station, thus simplifying the return of the treated ‘grey’ water as ‘green water’. The social acceptability of reusing treated effluent however, even as a ‘no contact’ ‘Green Water’ secondary supply, has yet to be tested on a large development in the UK and responsibility for the consistent delivery of its quality parameters has to be assumed by a competent and accountable body.
2
There is adequate potable water, and hence adequate wastewater for local treatment and return (secondary) supply with or without the comprehensive capture of rainwater or storm water run-off
3
Modest areas of land may be available for development of small scale, on-site waste water treatment plants either for discharge to watercourse or recirculation as ‘green water’, An alternative option might still be to treat all wastewater at the works currently operated by TW and redistribute from the centre.
Challenges to/ barriers against a ‘Green Water’ system 1
Currently there is no overall unified responsibility for the whole water cycle management for the Whitehill Bordon area – divided between SEW, TW and Kelda Water Services. Whilst this might have its strengths in the present situation, there are complexities which will need to be addressed if the system is to change to deliver an Integrated Water Management service.
2
Above and beyond the difficulties of integrating two ‘potable’ water systems (SEW and Kelda) into a single network, or at least upgrading the Kelda network to DWI compliance, responsibility for delivering a secondary green water system will require either much closer collaboration between the incumbent suppliers, or – as indicated in the stakeholder workshop of 3/2/11 – the possible
The social acceptability of treated effluent blended with a rainwater or SuDS component as the basis of a ‘Green Water’ supply also has yet to be tested but may prove to be a more acceptable option. Points favourable to a ‘Green Water’ supply: 1
There is a requirement from DEFRA and the EA to deliver a ‘water neutral’ solution (or as close as possible) for the ecotown development
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establishment of a ‘town water company’ which can produce and supply a green water solution. The potential for a ‘Town Water Company’ is discussed below. 3
The existing discharge consent for suspended solids at the Bordon STW is 25mg/l, whereas the suspended solid content of ‘green water’ should not exceed 10mg/l. Therefore a slight tightening of this parameter will have to be addressed.
tariffs (see Table 12) as a baseline and without regard for the SEW trial seasonal charges. Taking 2016 as the first year (some development completed) and when all new homes will have to comply with the Code for Sustainable Homes (CSH) Level 6 (80 litres per head per day of potable water). The figures below are rounded where appropriate since they are a guide not a detailed picture. Example:
9.3 Metering & Tariffs SEW have set themselves the target of having 90% of the properties they serve on a meter by the year 2020. From the outset, this target is feasible in new properties in Whitehill Bordon. All new properties may be assumed to have to be metered. Those on Rateable Value or ‘Assessed Water Charges’ will be encouraged to move to a metered supply, particularly in the Water Neutrality Zone of Influence. Whenever properties change ownership, it will be assumed that a meter will be installed. The target will be for 100% metering although to achieve this is unlikely in the short term. For the purposes of calculation therefore, a speculative estimate for future tariffs is based on a metered supply through a 15mm supply pipe to a new build domestic premises, using the 2011
Household of 4 people @ 80l/h/d = 300 (0.3m3/ day) = 100m3 per year (potable water) Additionally the same household might consume 30 - 40% of ‘green’ water for toilet flushing, garden and car washing (some might add clothes washing machines): Hence 0.12m3/d = 40m3/ yr. Possible tariffs for potable water (based on Table 12), omitting standing charges and assuming (unspecified) inflation each year from 2011: South East Water: £1.50/m3 Southern Water: £1.80/m3 Portsmouth: £0.85/m3 So our sample household would be spending £150, £180 or £85 respectively on potable water.
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9.4.1 Noting that sewerage charges are based on 90% of the total water supply quantity (140m3/yr) at a rate of £0.59/m3 (TW), our sample household will also pay £74 for sewage treatment. Therefore, what would be a fair and reasonable charge for the ‘green’ water supply to make it attractive as an option both for customer and supplier? There are a number of factors to take into account for an actual price but 80% of the potable water tariff might be sufficient incentive. This would reduce the total bill from £284 to £272, a saving of 4-5%. In order to truly influence behaviour the ‘green’ water could be metered and priced separately. These are not questions which can be readily answered out of context, but which should form part of a totally changed structure, and which might be included as part of a Multi Utility Service Company (MUSCo).
9.4 Town Water Company This topic is considered in more detail in this section since it was raised as a possibility during the Stakeholder Workshop of 03/02/2011 held at Whitehill Bordon. The concept of ‘Integrated Water Management’ might be successfully applied at the Whitehill Bordon Eco-town.
Potable Water Supply
In the first instance formal agreement would have to be drawn up to enable all contributing borehole operators to supply water on an equal basis with regard to quality and price. The situation with regard to the MoD boreholes is still unclear. It is probable that the St Lucia borehole (Zone 3) would not be proved to be suitable for use for a potable water supply, but might be considered as a dedicated fire fighting supply, or some such use which would not be compromised by a small degree of bacteriological contamination. It might be used as a back up supply for the non-potable (‘Green Water’) system and the quality kept under review over time to ascertain any improvements as a result of remedial/improvement works. The MoD Quebec borehole (Zone 3) would have to be linked to the wider network, assuming that the water left the existing MoD treatment plant at the same quality or better than the SEW supply. Given the data supplied by Kelda Water Services, it would appear that having passed through the treatment works the water meets all the criteria for private potable water supply and probably DWI. 9.4.2
Wastewater Treatment Treatment
There are a number of options which might be adopted for the Whitehill Bordon area and eco-town, constrained perhaps by the requirement to produce a ‘green water’ supply: •
Centralised
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• •
Divided Decentralised
A centralised system might continue to drain all sewage to the Bordon STW which would require significant expansion to meet the increased flow. However, as the Bordon STW already receives inflows from the MoD, the initial development of the site would replace any flows that already exist, thus the Bordon STW would not have to be upgraded or improved in the first phase of development, but instead could continue to serve the first group of inhabitants of the eco-town. As a ‘divided’ option, the MoD Pumping Station could be modernised and rebuilt with increased capacity as a STW, so that the two STWs work in tandem. The timing of a new on-site STW is a matter of discussion and would have to be agreed with Thames Water. However, foul effluent records for the MoD site could inform a timetable for construction and operation of the new STW, based on the existing loadings and projected loadings from the eco-town's population forecasts. Any new STW would need to be designed to suit the hydrological and biological capacity of the Oxney Drain which would inform a discharge consent application. It first needs to be determined whether or not an inset/ town water company will be established, as this will determine whether a new STW is constructed as well as the point of discharge. This analysis and decision will be informed by the town/ inset water company study.
In a ‘divided’ STW scenario the ‘green water’ would require less pumping around the new network, and the ex-MoD STW would serve many of the eco-town properties. A decentralised system might envisage smaller treatment plants in each sector of the existing and new towns – the advantage being that large volumes of wastewater could be treated locally and resupplied (‘as green water’) with less energy expenditure. In a ‘decentralised’ STW scenario increased maintenance responsibilities and risks of failure causing pollution need to be weighed up against the energy savings. 9.4.3
‘Green Water’
As stated above, the management of ‘green water’ is complicated in the existing Whitehill Bordon situation due to the separation of water supply and wastewater management. The question immediately arises as to who treats and delivers ‘green water’ since one or other of the two incumbent companies will be excluded from a stream of revenue derived from the treating and supply of ‘green’ water. Is this the domain of the deliverer of water (i.e. SEW) or of the company responsible for the treatment of wastewater (i.e. TW)? Or would the involvement of a third company responsible for ‘green water’ and its use of SuDS water be the ideal solution?
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This can be resolved by the formation of an Integrated Water Management company who would manage all water services. A representation of this arrangement including the water, licensing and monetary linkages is provided in Figure 21.
9.5 Retrofitting A number of water companies in England have made modest attempts to work with customers on retrofitting water saving devices. Waterwise has also published a number of leaflets explaining to householders how to install a menu of simple devices to reduce domestic water consumption such as pressure reduction valves or aerated devices for showers. The drive by most water companies to install or replace water meters to encourage people to monitor their own consumption has had moderate success, but the 90 - 100% metering target for England & Wales has yet to be reached by a long way. Currently, approximately a third of all domestic properties in the UK have water meters installed. However, since energy conservation has been given promotional priority by successive governments savings in this field are more likely to produce greater immediate financial benefit to householders, water conservation has taken very much second place, except under drought conditions.
Figure 21 Possible Water Arrangements
In Ashford, Kent a pilot project was undertaken in 2010 jointly by Ashford’s Future and South East Water working through CEN (Creative Environmental Networks) to visit and retro-equip 600 existing households with energy and water saving devices. The results of this initiative are reported in ‘Promoting domestic water and energy efficiency: A review of the pilot ‘Savings at Home’ retrofit intervention’ (Sharp and Macrorie, 2010). This is
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an important report, not so much for its technical information but particularly for its social insights – for example, it was found that whilst there was initial significant suspicion on the part of the recipient householders to allow the small team (a plumber and an ‘energy’ person) into their homes to fit ‘something for free’, word of mouth soon got round that it was a genuine and valuable offer, worth being part of. Community acceptance was much more effective than leafleting or offers for DIY. In parallel with this intervention, a second project called ‘Savings on Tap’ has been rolled out in Ashford. South East Water teamed up with Hillreed Homes, Kent County Council and the Environment Agency to equip all 200 new homes on the Highland Park development with water efficient appliances and fittings including: •
Water saving wash basin and outside tap
•
Ultra low dual flush toilet
•
High performance shower with aerated head
•
A+ rated washing machines
•
Rainwater butts
There are lessons to be learnt for Whitehill Bordon from these Ashford case studies: 1) That new build housing offers new opportunities for innovative water management strategies and conservation techniques 2) That community engagement from the earliest stages will produce greater cooperation when technically more intrusive projects (such as fitting dual plumbing for a ‘green water’ system) are offered as part of a retrofit 3) That the dual offer of energy and water conservation measures make a retrofit intervention more acceptable and attractive to householders 4) That the attitude and approach of the fitters themselves is a very important key to implementing retrofit
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The water company (SEW) agreed to pay for the extra cost of the fittings and to take responsibility for the monitoring of water use – taking on the project management after the construction phase. The conclusion was that a number of new departures, including variable tariffs, could be embedded in housing being constructed on brand new estates.
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10 Legislation & Regulations 10.1 Introduction This section discusses potential challenges in the existing regulatory regime and possible changes or new measures which might be required in order to meet the aims of the ecotown to achieve water neutrality using the options which are identified in this study. As has been recognised by the Environment Agency in its own guidelines on achieving water neutrality, referred to in Chapter 4, there are many factors which create obstacles and these will need to be addressed in full to ensure the ultimate goal is achieved in a sustainable long term manner. There might need to be an aspiration for certain changes to be made, particularly in legislation and regulations which this section highlights but this will act as a driver for promoting these changes. The local measures might need to be adopted in isolation as a trial before these more fundamental changes to the overall legal framework occur.
10.2 Primary measures Legislation Currently the control mechanisms governing the provision of water fall under the legislation described earlier in the study (Chapter 3). This legislation presents a number of blockages to achieving the aim of water neutrality. However, there is an opportunity currently available in the Floods and Water Management Act 2010 which has only been implemented in part through Statutory Instruments. A number of the provisions in this Act yet to be brought into effect could be of benefit to the aims of the eco-town. Some of these could be informed by the White Paper for water, now expected late 2011. The House of Commons Environment Food and Rural Affairs Committee published their first report on future flood and water management legislation in Dec 2010. This addresses a number of issues which are relevant to this study and makes recommendations for consideration by Defra in:
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Clear definition of the responsibilities for adoption of SuDS and the provision of adequate funding for the continued maintenance.
Greater customer engagement in price setting,
Social tariffs to alleviate rising bills for low income families,
Implementation of widespread metering and variable tariffs to incentivise efficiency,
More robust mechanisms to enable water companies to tackle bad debt such as contractual responsibilities on customers.
Careful consideration of mechanisms to introduce competition
The need to consult water companies on development proposals over 10 houses or 1ha
Reform of the abstraction regime to reflect the wider value of water
Regulatory reforms to include stronger water efficiency targets
Proposals on how the requirements of the WFD can be met and who should bear the costs
Statutory rights of consultation for water and sewerage companies on any application requiring connection to the public drains and rights to put right any incorrectly connected drains
In advance of the publication of the Water White Paper these recommendations provide a good basis for determining the kind of regime that needs to be established at Whitehill Bordon in order to achieve water neutrality. They represent the likely future of water management in England and therefore the proposals for a highly sustainable community is ideally positioned to test the viability of such a regulatory framework.
10.3 Secondary measures measuresRegulations In parallel with the changes to primary legislation that are likely to come out of the Water White Paper, there are regulations which are currently being prepared to implement various sections of the Floods and Water Management Act. These relate predominantly to river and coastal flood risk management as well as the management of SuDS. There is very little currently on the parliamentary programme at present which will change aspects of the water industry.
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10.4 Tertiary measures â&#x20AC;&#x201C; Local measures Taking into account the discussion in Chapter 3 and the review of legislative and regulatory issues which need to be implemented to overcome the obstacles to achieving water neutrality, this section describes the possible local bye laws and legal entities which could be established by the relevant authority in the eco-town to enable some of the issues to be addressed. 10.4.1
EcoEco-town Byelaws
Establishment of a Water Management body. This body could be made responsible for ensuring that all aspects of the water cycle within the eco-town boundary and possibly even the Zone of Neutrality are considered in all stages of development and operation. This body might be incorporated into a Town Water Company which is licensed by an Inset Agreement from OFWAT, but it should have some local representation on the board to ensure there is continued engagement of the population in the provision and management of water in the eco-town. The responsibilities would include adoption of SuDS and the provision of adequate funding for the continued maintenance.
The Water Management body would also provide an opportunity for greater customer engagement in price setting along with universal metering, and the potential for variable tariffs to encourage responsible water use, social tariffs to alleviate rising bills for low income families and some local mechanisms to enable the relevant organisation to tackle bad debt such as contractual responsibilities on customers. This may be difficult to implement within such a small area as the eco-town and non-payment might be better dealt with through education and engagement in the community. A Town Water Company would need to be much more closely engaged with the community and able to explain its charges more clearly but these will always be compared to prices charged in neighbouring areas. This should provide reasonable comfort with regard to competiveness. The Water Management body would need to be a consultee on all development proposals as the eco-town develops to ensure standards are maintained and water and drainage issues are properly dealt with in order to achieve the highest water efficiency targets appropriate to technology available. The sources of water should be clearly defined and costs associated with them also identifiable. The Water Management body is to include a monitoring regime and reporting mechanisms to demonstrate progress on all water related
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matters over time to show how specific targets are met, in particular in relation to the WFD and Habitats Directive.
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11 Recommendations & Further Investigations
Parts of the conventional surface water drainage system may still be suitable to use as part of the eco-town proposals, although this will depend upon the final development layout and the outcomes of a detailed hydraulic modelling investigation to ascertain the performance and capacity of the existing system
The final surface water drainage system must tie in with the GI programme for the development. In the preparation of the GI programme, PBA has supplied from this study the preliminary indicative areas for surface water attenuation to Halcrow, which will help to quantify the amount of available land to be retained as public open space.
11.1 Recommendations & Design Guidance The following section outlines the preferred options for the management of water resources within the eco-town, providing an indication of feasibility, costs and design guidance for future development of the site 11.1.1
Surface Water Drainage
Approach
Principally, the site should use sustainable drainage methods to control the quality and quantity of surface water runoff from the development.
Where possible, the existing surface water drainage system within the MoD site should be retained and combined with sustainable drainage measures, such as swales, infiltration measures and conveyance pathways.
Infrastructure Costs An indicative cost allowance for SuDS measures has been derived based on the volume of surface water storage required and standard charge rates provided by SPONâ&#x20AC;&#x2122;S Civil Engineering and Highway Works Price Book (2009) for excavation, disposal and an indicative allowance for other construction costs (e.g. headwalls, pipework and other structures).
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Work
This costs estimate does not include for any amendments to the existing surface water drainage network serving the MoD site. To obtain such an estimate would require survey and hydraulic modelling of the existing drainage system to establish what infrastructure needs to be replaced. The Turner & Townsend High Level Infrastructure Feasibility Cost Plan had made an allowance for the conventional surface water drainage network of approximately £1,500,000, which is based upon replacement of the main network. Based on these assumptions, an indicative cost allowance of approximately £1,300,000 should be made for the SuDS measures. Table 12 provides a breakdown of how this cost estimate has been made. Design Guidance
Discharge from the development must be restricted to the Greenfield runoff rate. Surface water storage must be provided to allow sufficient attenuation for the 1 in 100 year (with a 30% allowance for climate change) storm event.
Description
Unit Rate
Assumptions Assumptions
1.5m³ tractor loader and Using storage 22.5t ADT - Double requirement for 1 in handling of excavated 100 year ICP SuDS earth other than rock or methodology + Excavation £4.46 artificial hard material Freeboard allowance, 300m average distance 70% Development moved (page 174) Density Based on multiplying the excavation rate by 1.30, Adjusted the rate of Disposal equivalent to disposal of 1.3 excavated material by 'Compacted Soil Bulkage' 1.3 (page 166) Indicative allowance for Assumes 25% of Additional pipework, complex 25% Excavation and Allowances controls, headwall Disposal Costs structures etc. Table 12 Indicative costs estimate for Sustainable Drainage Measures (Source, SPON’S, 2009)
Surface water attenuation measures must be located outside the 1% annual probability (1 in 100 year) with climate change, flood extent.
Selection of sustainable drainage measures should be in accordance with the hierarchical approach set out in Table 13, which has been informed by guidance from CIRIA C697 ‘The SuDS Manual, and EA best practice guidance
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Volume (m3)
Cost (£)
180,000
£802,800
180,000
£234,000
N/A
£259,200
Most Sustainable
Least Sustainable
Flood Reduction
Technique
Pollution Reduction
Landscape and Wildlife Benefit
Green roofs, grey water recycling, rainwater harvesting Infiltration, Soakaways Above ground attenuation, Swales Piped drainage × × system Oversize × × underground tanks Table 13 Hierarchical approach towards choice of SuDS Measures
Drainage will need EA approval to confirm that any reduction in discharge to receiving systems does not have an adverse affect on water quality, quantity and affected habitats.
11.1.2
Flood Risk
Approach
It is an eco-town principle that inappropriate development will not be located within the floodplain. It is proposed that sequential approach is adopted towards development allocation, and areas of the site with a significant risk of flooding are used for ‘water compatible’ development only (in accordance with PPS25).
Under national policy guidance of PPS25, the eco-town will not have a detrimental impact on flood risk, and will, where possible, aim to reduce flood risk elsewhere.
The total discharge and volume of surface water leaving the eco-town will be lower than the existing discharge rate for the development within the eco-town boundary, leading to a reduction in downstream flood risk.
Infrastructure Costs Any infrastructure costs associated with the restoration of the Oxney Drain will be defined following the completion of a hydraulic modelling study and an agreed approach with the EA. Although local stakeholders have raised the issued of flooding caused by certain structures throughout the Oxney Drain, there is no specific information on where flooding has occurred in the past and what hydraulic structures are causing the issue. Design Guidance
There will be no inappropriate development within the floodplain.
If development is located within the floodplain (e.g. bridge footings, buildings) then floodplain storage compensation must be provided up to the 1% annual probability (1 in 100 year) with climate change event, on a level-for-level, volume-for-volume basis.
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Finished floor levels must be set to 600mm above the 1% annual probability (1 in 100 year) with climate change flood level, or 150mm above surrounding ground levels (whichever level is greater).
The soffit of any proposed access crossings must be set to 600mm above the 1% annual probability (1 in 100 year) with climate change flood level.
The EA recommend that there should be no raising of ground levels within the floodplain.
Any development, ground raising or related activity which is within 8m of a designated main river requires the written consent of the EA under the terms of the Water Resources Act 1991, irrespective of any planning permission being granted.
11.1.3
Water Supply Supply
terms of the local hydrogeological regime and nil-detriment to the ecology and habitats of the surrounding European Designated Sites. This option would also be the more favourable in terms of compliance with the Habitats Directive and WFD (although a further detailed hydrogeological study is required to confirm the interconnectivity and water resources shared between the town and the surrounding designated sites).
Water demand modelling has demonstrated that the ecotown cannot be sustained entirely by the MoD supply (unless the abstraction is increased above its current operating limits) and therefore the town would also require a green water recycling solution to satisfy the potable and non-potable water consumption. This approach would also help to achieve the eco-townâ&#x20AC;&#x2122;s goal of being Water Neutral.
A direct supply of potable water from the SEW distribution network would eliminate the cost of any infrastructure associated with treatment, collection and supply of green water. However such a solution would also require a greater volume of potable water and increased groundwater abstractions from the existing SEW supply boreholes.
This option would also be least favourable in terms of compliance with the Habitats Directive and WFD as any increase in groundwater abstraction may be detrimental to
Approach
The development requires a potable water resource. This can either take the form of a continued abstraction from the MoD supply borehole, or, a direct supply from the SEW potable water distribution network.
Continuation of the MoD supply within the limits of the current abstraction would have the greatest benefits in
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that the River Wey Catchment is classified as ‘No Water Available’ according to the CAMS.
A conceptual diagram (provided by Water Works UK Ltd) of how the water supply network may be designed is provided in Figure 22.
Infrastructure Costs The draft Whitehill Bordon Eco-town High Level Infrastructure Feasibility Cost Plan by Turner & Townsend reports that the costs associated with off-site reinforcement works to supply the eco-town with a potable water connection to SEW's distribution network would be in excess of £4,000,000. This estimate is based upon 9km of additional pipework as well as provisions for pumping stations, temporary works, traffic management and upgrades to existing reservoirs.
Figure 22 The Local Loop - Conceptual Diagram of Water Supply Network (Source: Water Works UK Ltd, 2011
the designated sites. The EA would also be unlikely to grant any increase in groundwater abstraction on the basis
If the site was solely reliant upon continuation of the MoD supply then there would be no requirement for any off-site reinforcement works. However, there are cost implications associated with formalisation of the MoD supply, potable water distribution, green water supply and distribution, and grey water collection. The Turner and Townsend report has already quantified the costs associated with the potable water and grey water mains. Table 14 outlines the indicative costs for the potable water, grey water, green water and black water mains. Where the costs differ to the Turner and Townsend report commentary has been provided.
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The above costs account for the primary infrastructure only, and not the plot-scale infrastructure. The costs associated with the existing borehole pumping, water treatment and iron removal facilities at the MoD site are an unknown quantity. It is likely that existing pumping and treatment infrastructure could be retained, but due to the complexities of the incumbent water services provider (BREY/ Kelda Water Services) there is relatively little known about the form and condition of the existing infrastructure arrangements (e.g. does the well casing need replacing? Will BREY/Kelda require compensation for their equipment? Are there existing contamination issues which require mitigation). At this stage there are too many unknowns to produce a reasonable costing for this abstraction. There will also be additional costs associated with obtaining and maintaining an EA annual abstraction licence for the groundwater abstraction (which is currently exempt from EA abstraction licensing). The EA has an online abstraction license cost calculator, but this is not appropriate to inform costs for public water suppliers and water authorities. For public water supplies the supplier has to enter into negotiations with the EA on licensing charges. Design Guidance
Quality: Green water should conform to biological criteria for tertiary treatment, typically <10mg/l BOD, <10mg/l Suspended Solids and < 5mg/l Ammonia, lacks turbidity <2NTU, is pathogen free (< 10cfu/100ml)
Consistency: Flow must be monitored automatically plus (where appropriate) in line chlorine dosing facilities to compensate for quality variation (minimum levels)
Construction of distribution networks: networks Suggest a ‘Multi Utility Services Company’ (MUSCo) approach whereby all services are provided within a single utility network. Such an approach has been discussed with LDA Design who are completing the Energy Feasibility Study in support of the development proposals.
Element
Cost
Potable Water Distribution Main
£3,000,000 (T&T estimate)
Grey Water Collection Main
£1,350,000 (T&T estimate)
Black Water Collection Main
£3,050,000 (T&T estimate)
£3,000,000 (This is based on the T&T estimate used for the potable water main, assuming that green water will be supplied to all new build houses) Table 14 Indicative supply infrastructure costs
Green Water Distribution Main
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11.1.4
Water Treatment
Approach
In terms of black water treatment and disposal the ecotown waste water can either be pumped out towards the TW Bordon STW, or, as discussed with representatives from TW and local stakeholders, a new STW could be created at the site of the MoD pumping station (formerly a STW for the MoD garrison).
TW has expressed their concerns that the Bordon STW lacks the capacity to receive any further foul effluent, and would require significant capacity upgrades. Local stakeholders are more supportive of a new STW located within the boundary of the eco-town.
If a green water recycling and treatment solution is being sought then a centralised/ site waste water treatment facility might be preferable (and more manageable) than two separate treatment facilities.
Owing to legislative obstacles, it is unlikely that SEW or TW would be willing to take on the responsibility of ownership and maintenance of a green water treatment facility. Therefore, the more likely option (which is preferred by local stakeholders) is to have an inset water management company (or town water company).
Again, establishing a green water treatment and distribution facility would assist in meeting the eco-town’s goal in achieving water neutrality.
Infrastructure Costs The Turner & Townsend infrastructure costs include an allowance for upgrades to the existing sewage treatment works which include ‘sewage recycling’ (i.e. treatment of foul water and redistribution of water within the development), assuming a cost of £1,500,000. As part of the WCS, indicative costs for a combined foul and green water treatment facility have also been considered. These figures are based on PBA’s previous experience with cost estimates for foul water treatment facilities that include a water recycling capability. It is recommended that an allowance of £3,000,000 to £4,500,000 is made for the waste water treatment facility. The range of cost reflects a general order of magnitude and the uncertainty in the water supply specifications for the eco-town as it will need to be confirmed whether a green water supply will be provided. Element
Cost
Foul Water Treatment
£2,000,000 to £3,000,000
Green Water Treatment
£1,000,000 to £1,500,000
Table 15 Indicative treatment infrastructure costs
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inset commitment owned and managed by the town, or at least by its operating agent, and which would probably draw on the existing infrastructure of the current incumbents. SEW could still be used to deliver a bulk supply at a monetary discount to the Town Water Company would administer the distribution of potable water and green water.
Design Guidance
Sewerage needs to be designed in accordance with the most recent version of Sewers for Adoption.
Developers must ensure that there is a maintenance agreement in place with the water management company to maintain and operate the green water and foul water treatment facilities.
The final sewage treatment system will have to be designed in close consultation with the EA to ensure that any reduction in discharge to receiving systems does not have an adverse affect on water quality, quantity and habitats.
11.1.5
Ownership and Maintenance
Approaches
To make any significant changes in the water management regime for Whitehill Bordon requires merging of services under one water services provider. Efficiency savings may be made under the current arrangements with Kelda Water Services, SEW and TW, but it is highly unlikely that either of the two main water companies (SEW and TW) are likely to agree to the provision of ‘green water’.
One possible approach (and one which is preferred by local stakeholders) is to establish a ‘Town Water Company’ within the eco-town boundary, which could either be an
The implications are wide ranging and especially in times of financial constraint on the Local Authority, this solution may not be generally acceptable. It would require a team skilled in the operation of such a customer base.
Another option may be to use Kelda Water Services as the whole water cycle manager within the inset appointment.
Table 16 provides an overview of the opportunities for water service provision and standpoints of various water companies.
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Water Company
Current Status in Whitehill Bordon
What requirements would be necessary to move to unitary supplier for Whitehill Bordon?
South East Water (SEW)
Potable Water Supplier (Source: Local Boreholes. Sufficient headroom till 2030).
Take management responsibility for wastewater and drainage. Not interested.
Thames Water (TW)
Wastewater Treatment and Drainage Services. Current STW at Bordon close to capacity.
Portsmouth Water (PW)
None. Serves adjacent area to the South.
Take over potable water supply. No available extra resources of their own in the catchment area. Not known if interested. Mostly borehole abstraction for own supply. Current boundary close to Whitehill Bordon.
Kelda Water Services (BREY)
Manages MoD potable water supply and collection of sewage. Pumps to Bordon STW.
Have 25 year contract with MoD for supply and wastewater. Not known if Kelda would remain on site, sell their contract or wish to become Inset Appointees for the whole development.
Could have spare borehole (well) capacity for GW supply, but insufficient for whole community, assuming some retrofit.
Inset Appointee
None yet in view.
Would need to satisfy at least one of the three conditions as laid down by Regulator: 1) A single customer taking over 50,000Ml/yr; 2) A Greenfield site (or brownfield with no existing supply; 3) By agreement with the incumbent/s.
GW supply would form part of the Inset Agreement. Would need to be managed from existing resources and blends of RWH, SuDs and treated grey water.
Town Water Company
None, but are all customers of either incumbent suppliers or MoD/ Kelda.
Both SEW and TWUL at a stakeholders meeting were of the opinion that a Town Water Company might be of interest. The Mayor of Whitehill is strongly in favour.
Local solution: RWH/ Grey water recycling/ SuDS etc. Interesting potential.
Green water (GW) supply Would SEW act as a supplier of GW? What would be the main source: RWH? SuDS? GW purchased in bulk from TWUL? Would TW act as supplier of GW? What would be the main source: STW? Grey water? SuDS? New venture altogether. Not known if even considered.
Table 16 Potential Water/ Wastewater Suppliers for Whitehill Bordon
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Infrastructure Costs Costs are impossible to determine at this stage of the eco-town proposals. It only makes sense to include costs if a water resources strategy has been agreed by all parties.
11.2 Proposed Policy 11.2.1
Inset Water Management Company
The need for an Inset Water Management Company at Whitehill Bordon is driven by the existing disjointed roles played by the existing incumbents, both statutory and private. As has been described throughout this study the closely linked parts of the water cycle are currently separated by significant corporate boundaries, all of an historical nature. These boundaries are also much bigger than the eco-town and therefore the particular arrangements being proposed here at Whitehill Bordon may not be of interest to these incumbents The opportunity presented by the eco-town designation is to define an area which includes existing dwellings but which will potentially include many more and which requires a major change to the water infrastructure in order for it to develop. This is an opportunity beyond “business as usual” in an area which is already a concern with respect to water. It is likely therefore that the solution can best be provided through an Inset Water Management Company, who may not yet exist as
an entity, but which could be created as the Town Water Company. The regulatory controls in the establishment of an Inset Water Management Company as defined in the Water Industry Act could create barriers to this basic notion and therefore the opportunity needs further investigation to determine the most effective route. The terms of reference and the responsibilities required in any inset agreement will need to be clearly defined to ensure no part of the water cycle is missed and therefore the commercial operation does not leave an unacceptable financial burden on the community. These terms of reference could be developed by the Water Management body who would take an overseeing role on the ongoing performance of such an organisation. The reason for the regularising of an inset agreement is to provide overall statutory control on a commercial entity to carry out its obligation to supply wholesome water to every residential dwelling and that this continues at a price agreed on a regular basis and a quality set out in the appropriate regulations. The obligation then extends to ensure the removal of waste water and treatment is undertaken in a manner which does not cause pollution and degradation of water resources and also at a cost which is acceptable and in line with competitive prices. The inset water management agreement provides a challenging problem, as any company operating within the ‘inset zone’ will effectively be operating within SEW’s Resource
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Zone 5 . Such a situation presents an issue of responsibility and management and where the boundaries lie. One solution may be to extend the inset zone outwards towards the zone of influence for water neutrality. Between the eco-town boundary and the outer limits of the zone of influence, there could be a joint responsibility agreement between the bulk operators (SEW & TW) and the Inset Water Management Company, whereby water resource planning, maintenance, protection and efficient are jointly managed. 11.2.2
Rainwater Collection
Rainwater collection should be viewed as providing an additional element of water supply. The water demand modelling has demonstrated that a green water recycling system can provide a sufficient quantum of green water for non-potable consumption by recycling and treating grey and black water. If any future development is to consider rainwater collection systems then the system must be designed with the necessary treatment stages to ensure removal of sediments and contaminants. In the case of a communal rainwater collection facility, which collects surface water runoff from the surface water drainage network, it must be ensured that:
according to the source of the surface water runoff, as per the SuDS Treatment Train as detailed in CIRIA C697;
A robust and comprehensive management strategy is completed;
Funding, maintenance and ownership arrangements are in place before construction.
There should be a move away from individual reuse systems in favour of communal collection, treatment where/ if appropriate and reuse. The property scale garden water butt (or two) is acceptable and effective for irrigation purposes. But the overflow should be conserved (and thus monitored) in communal storage tanks. At a property scale, if individuals or businesses wish to install their own rainwater harvesting measures then this must be completed in line with the Building Regulations and kept separate from any centralised/ communal rainwater collection facility. 11.2.3
Green Water
Assuming a green water recycling system and supply will be rolled out across the development, it is proposed that the following policies are put in place:
The surface water drainage network incorporates the appropriate methods and number of treatment processes
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All new homes should be dual-plumbed from the start to accommodate the secondary supply as and when it becomes available; Green water should conform to biological criteria for tertiary treatment, typically <10mg/l BOD, <10mg/l Suspended Solids and < 5mg/l Ammonia, lacks turbidity <2NTU, is pathogen free (< 10cfu/100ml);
EX 1 WaterP
Green water should be distributed via a networked system of pipework which is of a distinct colour or similar unique identifier to prevent accidental cross-connection to the potable water system (See Figure 23)
Grey Water If the development is to separate the foul water outputs into both grey and black water components as part of a green water recycling system, then it must also be ensured that kitchen sink waste is not to be included in the grey water category due to the prevalence of fats, oils and greases (FOGs). 11.2.4
A-D 178 MP XYZ K 6X2,2
2 89 12 3 SB 4 6892/9 1 IN D a A PE-X
ID: material, machine, year, week
Green water should be clearly identified as a separate supply, not for human consumption, by the use of a green tinged vegetable dye at a specified dilution; Name of product
DIN standard specifying pressure and temperature rating
Approval for potable water
Dimension (Outside diameter and wall thickness)
Production monitoring authority
Manufacturing process (Engel)
Figure 23 Green Water Pipe - Conceptual Diagram (Source: Water Works UK Ltd, 2011)
Individual grey water household systems (except in isolated locations) should not be permitted since they are potentially a health risk. Management is often â&#x20AC;&#x2DC;voluntaryâ&#x20AC;&#x2122; by the householder. This presents too great a risk when children or elderly people are present. Grey to green water treatment must be formally managed with due care and supplied by a competent organisation. Developers need to be aware of the greater risk associated with these than with a properly controlled central distribution system.
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11.2.5
Sludge and Macerators
Sludge removal is clearly an issue for competent bodies such as water companies and should remain that way. There is the issue of whether existing sewers can accept increased loads from maceration processes without greater potable water use to be used as a ‘flush’. Maceration at a property scale can only be introduced if the final waste water company is prepared to install Anaerobic Digestion (AD) at a strategic level. There are other aspects to consider such as the use of AD for energy generation to power the works. 11.2.6
Foul Water
Incorporation of water efficiency measures has the added complication of reducing the ‘flush flow’ through the existing foul water drainage network. Reductions in flow can lead to increased risk of blockage or failure of the foul water drainage network, which may in turn require a more frequent maintenance regime. One of the recommendations of the WCS is to conduct a survey or hydraulic modelling investigation of the existing foul water drainage network to establish the current operating conditions and capacity restrictions. The final foul drainage system should be designed to meet the criteria set out in the most recent edition of Sewers for Adoption,
and must consider lower flush flow volumes and maintenance regimes to ensure the system does not fail.
11.3 Behavioural Change 11.3.1
Positive Change
People’s perception of water needs to be changed within Whitehill Bordon (i.e. one major rainfall event, during a general year of low rainfall, does not mean that water resources are replenished for that year). However, in this situation there is a ‘critical mass’ (i.e. the existing population in Whitehill Bordon) to enable a local community approach that can encourage the idea of ‘shared responsibility’, where business, public and authorities can form partnerships to achieve water neutrality. The development of the eco-town depends on there being a secure and sustainable water resource, but there are wider issues for the local community to consider which outline the need for the eco-town:
Whitehill Bordon has long suffered from a lack of investment in infrastructure
When the MoD leave what will happen to the economy?
Development without improvements to the local infrastructure will eventually lead to development stagnation
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The eco-town proposals offer the opportunity to tackle these issues and also encourage more sustainable water management practices which are innovative, efficient, protect the environment and will reduce the cost to the consumer. The Waterwise report ‘The social science of encouraging water efficiency’ (2009) examines a number of projects and pilot schemes where communities, households and businesses have been encouraged to take up water efficiency measures. Some of the main findings of the report are presented below:
People genuinely believe that they are using water effectively and doing all they can to ‘save’ water.
People are aware that they can save water through routine actions in or around the home, but most people do not know how much water they are using or wasting. Consequently they do not know how much they could be saving.
Metering is perceived as a stimulus to saving water as it may reduce bills.
Some people without meters fear their bills will increase if they obtain one.
There is a perception that the ‘problem’ is mismanagement of water resources, not one of availability or demand.
People do not believe that their contribution to saving water will make a difference or is worth the effort. Water
companies need to show that they are committed to saving water too.
Almost all residents asked were happy with the water saving device (a dual flush retrofit system).
From the EA study, it appears that the main issues to overcome are:
Convincing and educating people that they can ‘do more’ to conserve water and they can make a real difference
People’s perceptions regarding ‘water metering’ and water efficiency measures
Changing people’s perception of water from an ‘abundant’ resource to a ‘finite’ resource.
11.3.2
Proposed Approach
To invoke any behavioural change, there needs to be an understanding of how different approaches, whether from economics, marketing, or the internet, could be relevant and effective to different people and situations. Increasingly PBA’s clients are asking for support on marketing and behavioural change interventions. For over ten years PBA has been one of the UK’s leading travel planning consultancies and we are now developing personalised travel planning programmes which specifically seek to increase public transport ridership. Using this experience, a similar approach can be adopted to achieve a shift in people’s perception of water and
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their consumption habits. Incorporation of a green water supply and water efficiency measures may be met with significant resistance and it is important to tackle people’s perceptions at a very early stage. It is also crucial that the method used to tackle people’s perceptions is not solely limited to one approach, as different sectors and individuals may be more receptive to certain approaches. Local Planning Policy (e.g. Water Cycle Study)
One option which could be considered for Whitehill Bordon Eco-town is to use the Advising, Enabling and Community Partnership approach (as outlined in Figure 24):
‘Advising’ phase would consist of dissemination of locallyderived policy information, which both outlines and explains policy as well as the necessary evidence to support it.
‘Enabling’ phase relates to effective marketing of potential solutions with a focus on highlighting the benefits of the proposed water efficiency and supply methods. This approach focuses on interaction with individuals and providing incentives.
‘Community Partnership’ phase is focussed on whole community involvement with a focus on sharing information and creating partnerships.
“Advising”
Dissemination of Information and Support (e.g. Events, Workshops, Eco-town shop)
“Enabling” “Enabling
Creating Positive Change (e.g. Partnerships, Sharing Information)
“Community Partnership” Figure 24 Approaches to tackling Behavioural Change.
Using this model, it is proposed that the following approaches are adopted to tackle people’s perception of water consumption, demand, supply and new technologies.
Partnerships
Set up forum/ working group with Whitehill Town Council, East Hampshire District Council, EA and SEW to discuss, agree and produce new methods to spread the water efficiency and innovation message
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The frequency of meetings should reflect the extent of the area under consideration
The partnership should also incorporate representatives from surrounding settlements (e.g. Headley, Headley Park) as well as key local landowners.
the overall water demand within the locality (e.g. advice in more efficient irrigation techniques)
Water Efficiency Programmes
Education
Using Whitehill Bordon Eco-town exhibition at the former MoD Fire Station to enable the public and commercial interests to access information. The water authority, water-efficient technology companies and manufacturers and social housing groups can operate out of this proposed exhibition space.
Distribution of simple-fix water efficient devices (e.g. hippo bags, aerated shower fittings).
As part of the retrofit budget, an allowance can be made for existing housing stock within the town to install low flush toilets.
Water efficient technology may be offered as an incentive as part of a ‘bundle’ when a water meter is installed.
Social Media
Either organise specific events or function as a drop in centre.
The water efficiency message should be directed towards children through schools and community groups.
A Twitter/ Facebook system can be created whereby ‘case study’ households can report on their own water consumption patterns, cost savings and experiences of new water tariff systems. Such information will also be useful for the local water company to track the progress and performance of various tariff structures.
Education should also be extended to commercial interests and agricultural landowners in the area, to offer alternative water usage strategies to reduce
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Such systems would allow for an open and unbiased information pool, where householders could share this information with the local population.
The public are far more likely to respond to word of mouth and peopleâ&#x20AC;&#x2122;s individual experiences rather than marketing literature, as this allows people to make their own informed decision.
between groundwater resources, watercourses and the European Designated sites in the locality. In accordance with EA criteria this assessment should:
The EA are particularly supportive of developing a strong educational campaign for protecting habitats and water resources in the locality, and as part of the eco-town proposals there may be scope to forge stronger links with local community groups such as the Deadwater Valley Trust, town partnerships such as Wildlife of Whitehill and regional conservation groups such as the Hampshire and Isle of Wight Wildlife Trust. Local people should have the resources available to enable them to take a more active role in water conservation and take ownership of water.
11.4 Further Studies 11.4.1
LongLong-term Hydrogeological Monitoring Study
To adequately consider the implications of the development in the context of the requirements of the WFD and the Habitats Directive will require monitoring of the local hydrogeology. Such an assessment must identify the hydraulic continuity
Assess the existing interactions between the European designated sites and the groundwater resource, their current condition and tolerance to increased hydrological stress in terms of water quality and water quantity. Assess the potential impact of the eco-town on watercourses and wetlands within the area in terms of water quality, biological and chemical, and quantity.
As part of this assessment watercourses and associated wetlands should be characterised to enable environmental sensitivity to be assessed and therefore evaluate level of risk from changes in hydrology and water quality. The characterisation should refer to the EAâ&#x20AC;&#x2122;s macroinvertebrate, fisheries and macrophyte data and include a summary of regional and local sites, and species of principle importance for biodiversity. 11.4.2
Ground Ground Investigations
Before detailed design of the surface water drainage strategy can begin a ground investigation will have to be completed which assesses the suitability of the site for infiltration drainage measures. It is likely that this process can be tied-in with the contaminated land investigations.
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11.4.3
Hydraulic Modelling
For any future development to be approved hydraulic modelling of the Oxney Drain will be required. The flood risk from this watercourse has not been quantified by any previous hydraulic modelling investigations, and the Prince Phillip barracks area is known to have suffered from flooding from this watercourse in the past. As covered in Section 8 of this report, the baseline fluvial flood risk will have to be established initially before any proposals for channel restoration, deculverting or bank reprofiling works can be confirmed. Before hydraulic modelling is completed the EA will need to be consulted to agree an appropriate modelling approach. 11.4.4
Inset Agreement (Town Water Company)
The options for a local provider of water and sewerage services needs to be explored in more detail to establish the likely mechanisms and potential arrangements for such an entity. It might be that it forms part of a MUSCO, but the responsibilities it would need to take on with respect to water are worth defining at this stage as it will form the basis of ongoing discussions with all relevant parties. It is recommended a line of communication is set up with OFWAT to discuss the funding, structure and responsibilities of a Town Water Company under an inset water management agreement.
11.4.5
Other Studies
Discussions with the EA have identified two further studies which will need to be completed to take the development proposals forward and add value to the development proposals. The WFD requires a register of protected water resource areas. This register includes groundwater safeguard zones, which have allow member states to protect groundwater areas that are used to sustain human water consumption. They can therefore look quite different to the EAâ&#x20AC;&#x2122;s groundwater source protection zones. Currently, the MoD site is not within a safeguard zone, but upon the MoD leaving the site there may be a change in designation and the area surrounding the MoD borehole may become a safeguard zone. This would have implications in terms of water availability and land use practices within the limits of the safeguard zone. The issue of bacteriological contamination of the MoD borehole needs to be investigated further, prior to the supply being approved for use by the eco-town. The source and extent of contamination needs to be assessed through on site testing so that the appropriateness of the supply as a potable water resource can be confirmed, and a feasible engineering solution can be deigned to remedy the problem. The EA also recommend that an investigation is undertaken to confirm any instances of cross connection within the surface water and foul water drainage network across the MoD site. The scope of such a study is difficult to determine at this stage,
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but stakeholder consultation has confirmed certain areas of the MoD site which are known to suffer from ingress of foul water into the surface water drainage network. Such a study also provides the opportunity for potential cost savings for sewerage infrastructure, as it may be able to identify parts of the existing drainage network that can be retained (most probably associated with the existing MoD housing stock), which overall will be more sustainable than the wholesale re-construction of the site drainage system.
11.5 Water Neutrality The area surrounding Whitehill Bordon and the wider River Wey catchment is classified as an area experiencing water stress and the local CAMS has classified the locality as â&#x20AC;&#x2DC;No Water Availableâ&#x20AC;&#x2122;. The shortage of water is attributed to inefficiencies in water consumption, prevailing climatic conditions, over abstraction of groundwater resources and population. Through using a combination of the existing MoD abstraction and an innovative green water collection, treatment and distribution system, the potable and non-potable water demand for the eco-town can be met whilst still achieving water neutrality. The WCS has demonstrated that using traditional methods of water supply the water demand of the eco-town (1.87 Ml/d) cannot be sustained without increasing current rates of abstraction from groundwater resources. SEW has indicated that there is sufficient capacity to sustain the eco-town using the existing network of groundwater abstractions, but this
would require increasing the current licensed abstractions. The EA would have to be consulted at the appropriate time to determine whether this approach would be allowable. To overcome obstacles of maintenance and ownership, the green water system will have to be provided as a communal resource. Individual/ property-scale green water systems do not take into account the variability of water consumption, whereas a communal supply can overcome this. Individual/ propertyscale water harvesting/ recycling systems are difficult to maintain (Waterwise 2009), and would be unlikely to sustain the non-potable water demand. It is not recommended that the water demand for the eco-town is dependent upon the continued maintenance and operation of multiple green water collection, treatment and supply systems on a property basis, as failure to maintain such systems may result in contamination of the water supply, reductions in available water supply, inadvertently leading to an increase in potable demand which will not achieve water neutrality. System
Abstraction for Potable Water (Ml/d)
No Systems (Business as 1.87 usual) Green Water and Grey 1.14 Water Recycling Green Water and Grey Water Recycling including <1.14 Rainwater Harvesting Table 17 Water Supply Methods and Water Neutrality
Water Neutral NO YES YES + Betterment
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Table 17 summarises the merits of the various water supply methods on the basis of water neutrality, based on a normal water demand for the eco-town of 1.87 Ml/d. If current rates of abstraction are kept within the existing operating limits of the MoD abstraction then the status quo of the existing hydrogeological regime can be maintained. In effect there will be no increase in the water abstracted from groundwater resources, thereby achieving a â&#x20AC;&#x2DC;water neutralâ&#x20AC;&#x2122; development. The proactive incorporation of the sources of water from the development (Grey Water and Rainwater) into the non-potable Green Water supply, balanced with maintaining river flows, will also contribute to betterment in the local water cycle. Table 18 outlines some of the studies which will need to be completed as part of the eco-town proposals. This table also defines who will be responsible for completing the study and when the study will need to be completed. Timescales are defined as per the eco-town draft masterplan development phasing:
Short-term (up to 2015)
Medium-term (2015-2026)
Long-term (2026 onwards).
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Study Long-term Hydrogeological Monitoring Study
Description To identify the hydraulic continuity between groundwater resources, watercourses and the European Designated sites in the locality, in the context of the Water Framework Directive and Habitats Directive.
Timescales SHORT to LONG TERM: Needs to be undertaken prior to establishing any water management agreements and could be rolled out long-term.
Responsibility Eco-town Special Purpose Vehicle
Ground Investigations
Before detailed design of the surface water drainage strategy can begin a ground investigation will have to be completed which assesses the suitability of the site for infiltration drainage measures. It is likely that this process can be tied-in with the contaminated land investigations.
SHORT TERM: Can be undertaken after the MoD has completed their decontamination process at the site.
Developers/ MoD/ ecotown Special Purpose Vehicle
Hydraulic Modelling of Oxney Drain
To ascertain flood risk from the watercourse, inform Masterplan layout and channel restoration. This information will also be used to inform the Green Infrastructure Strategy.
Developers/ eco-town Special Purpose Vehicle
Inset Water Management Agreement
Early discussions must be set up with OFWAT to determine the requirements, costs, business structure and responsibilities of such a company.
Investigation into Contamination at MoD Borehole
Assessment of hydrological and biological capacity of Oxney Drain to receive discharge from new STW. Required to establish limitations of borehole, existing pollution issues and sources. Also, there is a requirement to establish capacity of the borehole in light of any Environment Agency licensing restrictions.
SHORT to MEDIUM TERM: Could be progressed immediately or following set-up of eco-town Delivery Vehicle. Also dependent upon development phasing. SHORT to MEDIUM TERM: Should be progressed immediately to ascertain the feasibility of this solution for water management. Again, this is dependent upon development phasing and discussions with OFWAT and incumbents. SHORT TERM: Can be progressed at the same time as the hydrogeological monitoring study to determine the extent of contamination and options for repair.
Eco-town Special Purpose Vehicle
Cross Connection Study
Required to show parts of the existing sewerage infrastructure which can be retained or require upgrade/ replacement.
SHORT TERM: Needs to be completed as soon as possible to inform infrastructure costs.
Eco-town Special Purpose Vehicle
Application for MoD Abstraction and Discharge Consent for new STW works
Any groundwater abstraction of discharge consent will first need to be approved by the Environment Agency. This is critical for determining the water resource management solution for the ecotown.
SHORT to MEDIUM TERM: Will be dependent in part on the outcome of hydrogeological monitoring and development phasing, as new STW may not be required until a later stage in the development phasing.
Developers/ eco-town Special Purpose Vehicle
Eco-town Special Purpose Vehicle
Table 18 Required Studies
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Glossary Anaerobic Digestion: A process whereby microorganisms break down organic material in the absence of oxygen, used for industrial/ domestic waste purposes and/or to release energy Aquifer: An underground layer of permeable rock or soil that yields water Aquifer Recharge: Infiltration of appropriately treated water to ground. Aquitard: A rock of lower permeability which could be used for groundwater storage Bedrock: Unbroken solid rock Black Water: Wastewater containing faecal matter and urine Boreholes: A hole that is drilled into the earth, as for building, exploratory or water resource purposes Dry Weather Flow: In terms of waste water treatment, the average daily amount of water flowing through a system during dry weather. Ephemeral: In ephemeral ponds, this is defined as a water body which is only present for a short period of time before drying up. Foul Water: The discharge from any sanitary fixtures or appliances.
Freeboard: In the terms of this study freeboard is defined as an additional allowance in relative level to account for uncertainties in calculated output, modelling assumptions and design guidance from relevant authorities Glauconitic: Refers to the properties of Glauconite, which is an iron potassium phyllosilicate mineral of characteristic green colour Green Water: Water that has been treated to a grade suitable for provision as a non-potable, secondary supply, usually, but not exclusively, in parallel with a potable supply, for industrial, residential or public use Grey Water: Typically refers to water directly collected from clothes washing, bathing, hand washing etc. Headroom: The amount of water available after meeting demand Hydrogeological Regime: The prevailing flow conditions and interrelationships within an areas(s) of geology Hydrological Regime: The prevailing flow conditions and interrelationships within a given catchment(s) Infiltration Blanket: An underground engineered structure which allows for the discharge of water directly to ground via infiltration
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Interfluve: A boundary in the direction of groundwater flow between adjacent watercourses Ml/d: Megalitres per day â&#x20AC;&#x201C; equivalent to 1,000 cubic metres per day
Water Stress: When the demand for water exceeds the available amount during a certain period or when poor quality restricts its use
Non Potable Water: Water not fit for ingestion by humans Potable Water: Water fit for ingestion by humans Quaking Bog: Form of bog occurring in wetter parts of valley bogs and raised bogs, and sometimes around the edges of acidic lakes where bog is beginning to form. Ferruginous: Containing iron oxides or rust Resource Management Zone: A defined area where the incumbent water authority has responsibility for water management and supply, usually defined by settlement boundaries, river catchments and geology Superficial Geology: The recently formed geologic surface or subsurface features SSSI: Site of Special Scientific Interest Water Neutrality: For every new development, total water use across the wider area after the development must be equal to or less than total water use across the wider area before the development (EA, 2009)
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References Allen, R. (1997) Conford Moor SSSI: Reconnaissance Hydro Ecological Study.
Sharp, E. and Macrorie, R. (2010) Promoting domestic water and energy efficiency: A review of the pilot ‘Savings at Home’ retrofit intervention, Unpublished, University of Bradford.
CIRIA (2007) C697, The SuDS Manual, CIRIA. South East Water (2008) Water Resources Management Plan. CIRIA (2010) C690, WaND: Guidance on water cycle management for new developments, CIRIA. CLG (2010) Planning Policy Statement 25: Development and Flood Risk.
Waterwise (2009) Preston Water Efficiency Initiative. Wildlife of Whitehill (2008) A Local Biodiversity Action Plan. WRC Publications (2006) Sewers for Adoption, 6th Edition.
Environment Agency (2009) Water Neutrality: An Expanded Definition. Enviros (2003) Bordon Garrison, Land Quality Assessment Report , Vol 1. Future flood and water management legislation –House of Commons Committee on Environment, Food and Rural Affairs Dec 2009 First Report of Session 2010-2011 Hampshire and Isle of Wight Wildlife Trust (1996) Flora of Hampshire, Harley Books. National SuDS Working Group (2004) Interim Code of Practice for Sustainable Drainage Systems.
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Appendix A: Drawings Appendix A - Mapping 24763/001/001 Bedrock Geology Type 24763/001/002 Bedrock Geology 24763/001/003 Superficial Geology 24763/001/004 Policy Areas 24763/001/005 EA Licensed Abstractions 24763/001/006 Existing Surface Water Drainage Catchments 24763/001/007 Indicative land take for Surface Water Attenuation 24763/001/008 Elevation Model 24763/001/009 EA Groundwater Source Protection Zones 24763/001/010 Existing Foul Water Drainage Catchments
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Appendix A - Mapping
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Appendix B: FAQs FREQUENTLY ASKED QUESTIONS Question
Answer
This is an area where there is no water - how can you possibly justify new development?
Although the Environment Agency’s Catchment Abstraction Management Strategy for the River Wey states that there is ‘No Water Available’ for the area, the existing MoD water supply borehole was not accounted for in determining this. The water cycle study has demonstrated that by using the existing potable water supply from the MoD borehole, in combination with an innovative water recycling system, new development is possible without a corresponding increase in water abstraction.
The sewage works is too small and stinks - how can it accommodate so many new houses?
How can you expect existing residents to reduce their water usage just for newcomers?
The most recent climate change projections forecast a reduction in summer precipitation for South East England, which will obviously have an impact on the availability and cost of water. Furthermore, by 2020, South East Water will have installed water meters to approximately 90% of its customer base, and with rising energy prices the unit cost of water is only going to increase. Such pressures raise the importance of using water responsibly. The eco-town will provide the opportunity for existing residents to reduce their own water demand through education, incentive schemes, advice and community partnerships. As part of the eco-town proposals some water efficiency devices will be distributed freely amongst the existing community, which may include low flush toilets, aerated shower heads, water meters etc.
The water cycle study has noted the limitations of the existing Thames Water sewage works at Bordon, which is already operating at capacity and cannot serve any major new development. It has been recommended that either a new centralised sewage treatment works is provided for at the site of the current MoD pumping station, or, the Bordon sewage works are upgraded/ modernised to improve the treatment process and increase capacity.
By taking a pro-active approach and providing this service, it is hoped that water consumption across the town can reduce, but more importantly the existing community will be ahead of the game in terms of responsible water use and cost savings.
I'm a farmer and the EA has told me
The locality is classified under the EA’s River Wey Catchment Abstraction Management
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they will not allow me to keep taking water, why should the eco-town be different?
Strategy as ‘No Water Available’, which means that water can only be abstracted from the environment under high flows. If the proposals to continue to abstract from the MoD borehole are agreed with the EA, then the eco-town will be maintaining the current rates of abstraction (maintaining the status quo) and therefore will not be having an impact above that of the current groundwater abstraction regime.
There are loads of new boreholes around, surely they should be stopped?
Anyone is able to abstract up to 20,000 litres of water per day without charge or an abstraction licence. Any new boreholes that require an abstraction above this quantity require an abstraction licence from the Environment Agency and the impacts of the abstraction would be assessed as part of the licensing.
If you take more water the SPAs will become damaged?
The water cycle study has demonstrated that the eco-town’s demand for potable water can remain within the current operating abstraction limits of the MoD borehole. Therefore, there will be no increase in the water abstracted from the groundwater supply – status quo is maintained and the situation of the SPAs will be unchanged.
You can't use the MoD water because EA have stated that they are not issuing
The EA are not necessarily averse to granting an abstraction licence for the MoD borehole. The EA need to be satisfied that continuation of the groundwater abstraction from the MoD
new licences?
borehole will not have a detrimental impact to sensitive sites.
What happens to the existing water services operator (Kelda/ Brey Water Services) at the MoD site?
Kelda (or Brey) are the water service provider for the MoD as part of the PFI agreement ‘Project Aquatrine’. The exact details of the contractual agreement between the MoD and Brey are unknown, but it is probable that the MoD may provide compensation for termination of any contracts with Brey upon vacating the site.
How are you going to be able to prove that there is no detrimental impact on designated sites?
The results from future proposed hydrogeological monitoring of the site and the wider area and pump tests on the existing MoD supply as part of the licensing process will show exactly what the capacity of the aquifer is, and from this information a picture will be able to be constructed to show whether or not there are any impacts. The Environment Agency will have the responsibility for the decision on whether a discharge consent will be granted and their decision will be based on the data collected from the hydrogeological monitoring study.
Is flooding around the Oxney Drain going to be dealt with?
Yes. The Water Cycle Study recommends that a computerised model of the Oxney Drain is constructed to calculate the frequency and extent of flooding of the Oxney Drain. This information can then be used to look at channel restoration options and flood risk
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mitigation measures. Any modelling, restoration or mitigation measures will need to be approved by the Environment Agency.
management of water within the town?
not just the new residents of the eco-town.
How are the limitations in the existing foul and surface water drainage network going to be tackled?
The Water Cycle Study has recommended that a wholesale survey of the existing MoD drainage system is undertaken to determine the existing limitations, identify areas of the system which do/ do not need replacing and also deal with any cross connection issues (i.e. surface water sewer connected into foul water sewer or vice versa).
What is Green Water, why do we need it and, how will it work?
Why bother having a town water company? Will this cost more?
Discussions with local stakeholders at the onset has shown that this is a very popular option, as it allows the community to take ownership of water. Furthermore, owing to the challenges of a potential green water supply, it is unlikely that the incumbent water authorities will be willing to adopt such an innovative system. A Town Water Company (which will be regulated by Ofwat under an Inset Water Management Agreement) can overcome this issue, and potentially provide a stable and sustainable means of income for the town (e.g. if the water company is owned and operated by a local partnership or Council)
Green water is water that has been treated to a grade suitable for provision as a non-potable, secondary supply, usually, but not exclusively, in parallel with a potable supply, for industrial, residential or public use. As the existing town is located in an area of significant water stress (i.e. any additional water can only be abstracted from the surrounding environment under high flow conditions) standard potable water supply arrangements will not achieve water neutrality. The green water solution allows about 40% of the water to be reused within the town and overcome this issue, allowing for a development which is innovative, sustainable, world-leading and most importantly water neutral
How can we be sure that ordinary people arenâ&#x20AC;&#x2122;t going to be excluded from the
The eco-town boundary encompasses the whole town including Lindford. The proposals allow for the roll out to all inhabitants of water efficiency measures, services and education,
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Appendix C: Water Demand Modelling Parameters & Output
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Appendix D: Stakeholder Workshop Notes
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Appendix E: Surface Water Drainage Assessment
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www.whitehillbordon.com Produced on behalf of Whitehill Bordon Eco-town East Hampshire District Council Penns Place Petersfield Hampshire GU31 4EX 01730 234 329
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