APPENDIX 1 CLIMATE CHANGE CONTEXT - Espace project

APPENDIX 1

CLIMATE CHANGE CONTEXT

Global climate change

1. Global temperature has risen by about 0.6°C since the beginning of the twentieth century, with about 0.4°C of this warming occurring since the 1970s (Figure A1.1). Recent weather records illustrate this trend: for example, 1998 was the single warmest year in the 142-year global instrumental record and 2004 was the fourth warmest.

2. So what is causing the warming? There is new and stronger evidence to show that most of the warming observed over the last 50 years is attributable to human activities1. Increasing industrialisation and the use of fossil fuels over the last several hundred years has exerted a major influence on climate. This activity has increased concentrations of greenhouse gases, such as carbon dioxide, methane and low level ozone, which trap more energy in the lower atmosphere and thus warm climate. Figure A1.2 illustrates this.

Climate change in the South East 3. Climate scenarios for the UK2 (commonly referred to as the UKCIP02

scenarios) provide information about possible changes to our climate, up to the end of the century. The scenarios reflect a range of possible future emissions, based on results from a set of climate modelling experiments. The actual level of emissions and hence climate change will depend on actions taken globally to limit emissions (or otherwise).

4. The ‘Low Emissions’ and ‘High Emissions’ scenarios are discussed here, as they set out the range of potential climate changes:

• Low Emissions (increase in global temperature of 2.0oC by the 2080s);

• High Emissions (increase in global temperature of 3.9oC by the 2080s).

5. Even if global emissions of carbon dioxide eventually fall below today’s level, as assumed in the UKCIP02 Low Emissions scenario, the future rate of global warming over the present century may be about four times that experienced during the twentieth century. If the emissions rate increases to approximately four times today’s level – the High Emissions scenario – the future warming rate may be about eight times that experienced during the twentieth century due to inertia in the climate system.

1 IPCC, 2001: Climate Change 2001: Synthesis Report. A contribution of Working Groups I, II and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change. 2 Hulme M et al. (2002), Climate change scenarios for the United Kingdom: The UKCIP02 Scientific Report, Tyndall Centre for Climate Change Research, School of Environmental Sciences, University of East Anglia, Norwich, UK.

Temperature changes

6. By the 2080s, average annual temperatures are expected to rise by between 2 and 2.5°C (under the Low Emissions scenario) and by between 3.5 and 4°C (High Emissions scenario) compared to the 1961-90 average (Figure A1.3). Summer temperatures are expected to experience more warming than winter temperatures (Figures A1.4 and A1.5). For example, by the 2080s temperatures are expected to increase in the summer by up to 6°C under the High Emissions scenario compared to a rise of up to 3°C in winter under the same scenario.

Precipitation changes

7. Rainfall patterns will change, with summers getting drier and winters wetter, leading to a modest decrease in average annual precipitation of up to 20% under the High Emissions scenarios (Figure A1.6). However, this annual trend obscures larger seasonal changes. For example, precipitation is expected to increase in winter by between 15% (Low Emissions scenario) and 30% (High Emissions scenario) (Figure A1.7), whereas in summer, precipitation is expected to decrease by up to 50% under the High Emissions scenario (Figure A1.8).

Wind speed

8. Wind speeds are expected to increase in winter, although this is only predicted with low confidence. Some increase in the number of days with ‘high’ wind speeds is expected. The UKCIP02 report suggests that the number of very severe gales could increase by 9% and 11% in winter and summer over the British Isles.

Seasonality and variability

9. The South East will also see changes in seasonality and variability. Seasonality is a measure of seasonal difference, for example between summer and winter. Seasonality will increase in terms of precipitation and temperature. Inter-annual variability provides an indication of the variation in seasonal temperature or precipitation that can be expected to occur from year-to-year as the climate warms. In the South East, summer and autumn temperatures will become more variable as will winter and spring precipitation. Understanding the likelihood of experiencing anomalous seasonal temperatures and levels of precipitation together can be useful for understanding potential climate change impacts. For example, the occurrence of high temperatures in a summer of low precipitation enhances drought conditions, while a warm and wet winter can result in higher rates of flooding and hence flood damage. Winter depressions are also likely to become more frequent leading to possible increased storminess, although there is a relatively low level of confidence associated with this result. Similarly winter wind speeds may increase somewhat, but there is, again, a high level of uncertainty associated with this result.

Changes in sea level

10. Sea level rise of between 19cm (Low Emissions scenario) and 79cm (High Emissions scenario) is predicted to occur in the South East, due to three factors: isostatic subsidence (on-going readjustment of the land to the de-glaciation that followed the last ice age) and climate-induced glacial melting and thermal expansion of ocean water.

11. Extreme sea levels due to storm surges are expected to increase in size and frequency. Figure A1.9 shows that simulated changes in the 50-year return period water levels (i.e. that water level which could be expected to occur once every 50 years) are by 2080 between 0.4m and 1.0m higher than experienced currently in the South East. However, there are high levels of uncertainty associated with these predictions due to the assumptions used in the modelling.

APPENDIX 2

‘WATER-RELATED’ CLIMATE CHANGE IMPACTS ON SPATIAL DEVELOPMENT AND THE BUILT ENVIRONMENT: BACKGROUND INFORMATION

12. The climate changes predicted to occur in the South East will lead to a range of ‘water-related’ climate change impacts, which will affect spatial development and the built environment, including:

• Flood risk

• Water resources and water supply issues

• Water quality issues

• Water related impacts on built structures (for example, increased weathering of building facades).

Climate change and flood risk 13. Climate change is likely to exacerbate the risk of flooding, due to higher

levels of rainfall in winter and more frequent extreme winter precipitation events.

14. Guidance for the construction industry on development and flood risk produced by CIRIA identifies seven categories of flood risk (Box A2.1), all of which are likely to increase in frequency and severity as a result of climate change.

Box A2.1: Flood risk mechanisms

Category Mechanism

Fluvial flooding Exceedence of the flow capacity of the channel of a river, stream or other natural watercourse, typically associated with heavy rainfall events. Excess water spills on to the flood plain

Coastal and tidal flooding High tides, storm surges and wave action, often in combination

Estuarial flooding and watercourses affected by tidelocking

Often involving high tidal levels and high fluvial flows in combination

Groundwater flooding Raised groundwater levels, typically following prolonged rain (may be slow to recede). High groundwater levels may result in increased overland flow flooding

Flooding from overland flow

Water flowing over the ground surface that has not reached a natural or artificial drainage channel. This can occur when intense rainfall exceeds the infiltration capacity of the ground, or when the ground is so highly saturated that it cannot accept any more water

Flooding from artificial drainage systems

Blockage or overloading of pipes, sewers, canals, and drainage channels or failure of pumping systems. Typically following heavy rain or as a result of high water levels in a receiving

watercourse

Flooding from infrastructure failure

Structural, hydraulic or geotechnical failure of infrastructure that retains, transmits or controls the flow of water

Source: Development and flood risk: guidance for the construction industry. CIRIA C624, 2004.

Fluvial flooding

15. The Environment Agency has recently finalised a new Flood Map for England and Wales which provides information on flooding from rivers and the sea and information on areas benefiting from flood defences. Whilst the new map does not build in climate change forecasts, it does also shows the potential extent of an extreme flood (with a 0.1% (1 in 1000) chance of happening each year), which may be experienced as a result of climate change3. Figure A2.1 illustrates flood risk in the South East as shown on the Flood Map.

16. Further research is underway to identify flood risk and flood defence needs in the region. For example, Thames Estuary 2100 is a joint initiative between the Environment Agency Anglian, Southern and Thames regions of the Environment Agency, working closely with the Thames Estuary Partnership and Thames Estuary Research Forum. The project aims to determine the appropriate level of flood protection needed for London and the Thames Estuary for the next 100 years taking into account climate change.

17. It is important to bear in mind that even if an area is currently defended to a particular standard, there is still an associated flood risk as defences may still be overtopped. The risk of this occurring will increase with climate change.

Coastal and tidal flooding

18. The expected rise in sea level as a result of climate change will increase the risk of the sea overtopping current defences or encroaching on undefended land leading to flooding. Coastal flooding is also likely to increase in frequency due to predicted increases in storm frequency and intensity. The Environment Agency Flood Map also provides an indication of areas at risk of flooding from the sea: the map shows the extent of a flood with a 0.5% (1 in 200) chance of happening each year, but again, this does not build in increased risks posed by climate change.

Groundwater flooding/flooding from overland flow

19. Groundwater flooding, which is already persistent in some parts of the region, may increase due to increased winter rainfall volumes, leading to longer periods of saturated soil conditions and a reduction in groundwater surface storage. As the number of winter days with high rainfall totals increases, so will the likelihood of high rainfall events occurring when the soil is already saturated. Therefore a high percentage of rainfall will run off overland directly into streams and rivers. This may result in riverine peak

3 www.environment-agency.gov.uk

flow rates being reached more quickly during rainfall events than at present and being high enough to overtop banks leading to flooding of surrounding land.

20. The Environment Agency Flood Map does not provide information on flooding from other sources, such as groundwater, direct runoff from fields, or overflowing sewers. Further modelling might be required in specific locations to identify such risks, or local Environment Agency offices may have more information on these types of flood risk.

Flooding from artificial drainage systems

21. Intense rainfall events or an increase in the frequency of local intense storms, which are likely to occur as a result of climate change, may overload drainage systems (including roof drainage, sewer systems, carriageway drainage, etc.) in urban areas causing localised flooding. This is an impact of potential significance in urban areas throughout the South East, particularly as new development puts increasing pressures on drainage systems.

Impacts of flooding on the built environment

22. Flooding can lead to extensive damage to building contents, possible contamination from sewage (‘foul flooding’), and structural damage. Some buildings could become uninsurable if they are in particularly flood-prone areas. The Association of British Insurers is currently looking closely at climate change impacts on the insurance industry, taking into account issues such as flood risk to properties and increasing risks of subsidence.

Water resources and water supply 23. More frequent occurrence of drought periods and the extension of the

duration of droughts will extend the period when soil moisture deficits occur, reducing the opportunity for ground water recharge and ultimately reducing water availability (Rising to the Challenge).

24. The Environment Agency is responsible for water resources strategy in England and Wales. Its Water Resources for the Future Strategy (March 2001) bases forecasts for water demand on socio-economic scenarios and takes a 25 year horizon, which includes a consideration of climate change impacts. The strategy notes that abstractions that need summer water will become less reliable and licence conditions that protect low flows will become effective more often.

25. The following bullet points present possible implications of climate change for water resources, as discussed in the Environment Agency 25 year strategy:

• Changes in the yields of reservoir systems and aquifers are uncertain, but it seems likely that there may be a reduction in yields.

• Direct abstractions will become less reliable in summer as groundwater levels are reduced.

• The water industry may face challenges to meet peak water demands when resources are depleted, for example in long dry summers, which will become more frequent.

• Household water use is likely to increase in times of peak demand (i.e. in hot, dry summers), and agricultural demand for irrigation will increase as summers get hotter and the growing season increases. Industrial use may increase, for example for air conditioning, but it is expected that industry will continue to develop water efficient technologies.

• Based on currently available resources and considering societal and environmental demands for water, it is likely that deficits will occur in the South East.

26. The Water Resources for the South East Group has explored the impact of alternative housing growth levels on the public water supply balance to illustrate a range of scenarios and inform the South East Plan. The modelling takes into account the level of growth, extent of water efficiency improvements, assumed sustainability reductions (i.e. reductions on availability enforced in order to protect aquatic habitats) and extent of new water resources brought online. Climate change considerations are built into the modelling to the extent to which water companies included a consideration of climate change in their data on which the modelling is based. This data is presented in Figures A2.2 a and b. The first shows water resource availability in 2025 with 30% above RPG9 levels of growth, no additional provision of water infrastructure and no increased in water efficiency rates in new housing development. The second shows the water resource availability in 2025 with 30% above RPG9 levels of growth plus water efficiency improvements of 8% in new housing and the development of new water resource infrastructure. It can be seen that if we hypothetically look at the consequences of accommodating high levels of growth on public water supply and demand, it is essential to plan for provision of new supply infrastructure alongside improvements in water efficiency of buildings.

Water quality 26. There are a number of water quality implications that may arise from changes

in the climate. Sea-level rise and coastal flooding may increase saltwater intrusion to vulnerable aquifers leading to a decrease in water quality. Increases in intense storms may increase the number of combined sewer discharges into rivers causing water quality problems.

27. Declines in summer rainfall volumes and the potential resulting loss of baseflow during summer months may lead to reduced dilution of effluent from sewage treatment works which would also cause a decline in water quality. This is of particular concern in those parts of the South East characterised by streams fed by groundwater baseflow derived from the chalk, and where groundwater abstractions are already having an impact on flow regimes.

Built structures 28. Greater evaporation may result in shrinkage of clay sub soils and more

subsidence of foundations, whilst seasonal changes in patterns of wetting and drying may increase ground subsidence and ground heave.

29. Increased winter rainfall volumes, intensity and storminess may increase weathering of building facades, and increase penetration of rain into building walls and interiors which may lead to structural collapse or at least problems such as mould.

APPENDIX 3

DETERMINING CLIMATE CHANGE VULNERABILITY AT THE DEVELOPMENT PROJECT SCALE: RISK AND UNCERTAINTY

30. In order to identify and require suitable adaptation measures at the development project scale, the local planning authority (and the developer for specific developments) must first understand the potential vulnerability of the local authority area (and specific sites within the local authority area) to climate change. This section of the Toolkit provides guidance on determining vulnerability to climate change.

31. The Planning Response to Climate Change published by the ODPM provides an overview of how to put in place policies that deal with adaptation to climate impacts while taking account of uncertainty about those impacts. The guide sets out a decision making framework for formulating planning policies that take account of climate change impacts (summarised in Box A3.1). This framework should be followed, with reference to the more detailed guidance provided in the ODPM guidance, when developing planning responses to the water-related impacts of climate change.

Box A3.1: Decision making framework for planning policies on adaptation Stage 1: Identify scope of the policy • What is the desired outcome of the policy? • Is the policy explicitly about adaptation to climate change impacts? • If the main driver is not related to climate change, is climate change likely to be a key

factor in the scope or success of the policy?

Stage 2: Establish criteria for policy making and exposure unit • What are the main criteria against which your options will be appraised in Stage 5? • What are the legislative requirements or constraints? • Will the policy constrain adaptation to climate change elsewhere or have knock-on

impacts on other decision makers? • Has climate change already been accounted for at a higher planning policy level? • Has the exposure unit been identified? • Have assessment endpoints and thresholds been identified?

Stage 3: Assess risk • What is the lifetime of the possible outcomes of the policy? • Which climate variables are likely to have a significant relationship to your policy? • How might future changes in these climate variables affect your decision? • Is it possible to judge the potential significance of particular climate change impacts? • Is there uncertainty regarding forecasts of particular climate hazards? • Can any climate variables be screened out? • What other factors could be relevant to meeting your criteria?

Stage 4: Identify options • What range of options should be considered? • What are the consequences of doing nothing? • Can No Regret or Low Regret options be identified?

Stage 5: Appraise options • How do these options rate in relation to the criteria established at stage 2?

• Do you need more precise definitions of these criteria to appraise the options? Stage 6: Formulate policy • Is there a clear ‘preferred’ option to form the basis of the policy? • Does the policy have implications for other decisions and policies? • Could it constrain others in their ability t manage the consequences of climate change?

Stage 7: Implement, monitor and review • Have monitoring systems been put in place to assess whether the policy is delivering

the desired outcomes? • Does new information e.g. on climate change require the policy to be modified? • How will monitoring information provide feedback for policy review?

Adapted from The Planning Response to Climate Change, ODPM 2004

32. A key element of the decision making framework is to assess risk (Stage 3 in the framework set out in Box A3.1), which involves identifying which climate variables are likely to have significant implications for an LDF policy/development control decision. The sections below provide some pointers for considering vulnerability to climate change.

ASSESSING RISK 33. The ODPM Guidance includes a climate-sensitive development checklist,

includes questions which should be answered to assess risk. Box A3.2 below includes an extract from the checklist focussing on water related risks, which LPAs should consider when preparing LDFs or making development control decisions.

Box A3.2: Assessing risk - Checklist

• Is the site in an area at risk from current or future climate change impacts and extreme weather events such as:

• Sea level rise

• Storm surges, extreme high water levels and tidal flooding

• Flash floods, slow onset flooding and fluvial flooding

• Groundwater rise flooding

• Land erosion/landslips/subsidence

• Storm damage

• Water shortage?

• Could development in particular areas potentially increase climate-related risks in the locality in terms of:

• Increased surface water run-off

• Causing changes to the flood or groundwater regimes elsewhere

• Increased pressure for new or enhanced flood or coastal defence measures

• Increased pressure for water resources?

Adapted from The Planning Response to Climate Change by ODPM 2004

34. The scenarios produced by UKCIP, discussed in Appendix 1, provide a good source of information for assessing vulnerability. However, these provide information typically at a 50km resolution, which means that whilst they can provide an indication of climate change vulnerability, they may need to be augmented by further studies at the regional or sub-regional level (the scale will vary depending on the type of risk and the type of decision one is seeking to make based on the assessment).

Assessing water shortage and pressures on water resources 35. Information on pressures on water resources in the South East is presented

in Appendix 2. From this it can be seen that virtually all areas within the region are subject to pressures on water resources.

Assessing flood risk 36. Flood risk assessment procedures which address flood risk at various scales

are developing rapidly. Box A3.3 below sets out flood risk studies/assessments undertaken at a range of scales (from the national level down to the level of specific developments) and their role in decision-making.

Box A3.3: Hierarchy of flood risk studies/assessments

Scale of study/assessment

Type of study/plan

Role in decision making

Responsible parties

National National food plain mapping by the Environment Agency

To identify the extent of areas at risk of flooding nationally to inform the risk-based approach to development proposals in or affecting flood-risk areas as set out in PPG 25

Environment Agency lead

Catchment Catchment Flood Management Plans/River Basin Management Plans/ Shoreline Management Plans

To identify flood risk issues and flood alleviation strategies on a catchment scale

Environment Agency lead

Catchment/District Strategic Flood Risk Assessments (SFRA)/ Preparation of issues and alternative options in LDF process and production of Development Plan Documents (DPDs) based on evidence base, sustainability appraisal,

To identify flood risk issues on a sub-regional scale to inform areas identified for development in DPDs

Local Planning Authority

consultations, etc.

Individual site or development

Flood Risk Assessment (FRA)

To identify and address flood risk issues associated with an individual development

Developer

37. The Environment Agency national Flood Map provides a broad indication of

flood risk across England and Wales (this is described in more detail in Appendix 2). As outlined above there are a range of risk assessments and plans which should address flood risk which take place below the national level, including Catchment Flood Management Plans, River Basin Management Plans and Shoreline Management Plans. Strategic Flood Risk Assessments undertaken by local authorities or groups of local authorities acting together, also provide a level of more locally specific information on flood risk (discussed further in Section 7).

38. At the level of specific development sites, developers may be required to undertake flood risk assessments (FRAs) (discussed further in Section 7). Guidance produced by CIRIA on Flood Risk Assessment4 provides a clear methodology to assess the risk of a site or area flooding, and to assess the impact that any changes or development in the site or area will have on flood risk. The guidance also provides an indication of how climate change should be considered in the FRA process, which is summarised in Box A3.4 below. Likewise the other flood risk studies and assessments identified in Box A3.3 above should also build in a consideration of climate change.

Box A3.4: Consideration of climate change in the Flood Risk Assessment process

The potential effects of climate change should be allowed for in an FRA, as recommended by current national planning policy guidance. Estimation of potential climate change impacts is an area of current and ongoing research, and climate change allowances may alter depending on the situation. It is recommended that the allowances which care to be made for climate change within an FRA should be agreed with the LPA/Environment Agency as part of the FRA process.

Assessing other water-related risks 39. Other water related impacts of climate change which should be considered

include:

• Land erosion.

• Landslips.

• Subsidence.

• Storm damage.

4 CIRIA 624 Development and flood risk guidance for the construction industry

40. Local authorities and developers should factor in the risk of such eventualities when making decisions in terms of where development should be permitted, and what adaptation measures should be built into new development.

APPENDIX 4A

MENU OF ADAPTATION OPTIONS TO RESPOND TO PRESSURES ON WATER RESOURCES The suitability of the following measures to respond to pressures on water resources should be considered when preparing LDF policy/making development control decisions:

Development specific measures

Water reduction Water efficient fixtures and equipment within developments: • Water-efficient devices, such as washing machines and dishwashers. It is likely that

water efficiency in washing machines will level out at around 30-40 liters per wash. Water efficient dishwashers currently use around 14 litres per cycle.

• Dual-flush and low-flush toilets, using 4 litre flush instead of the standard 6 litre, these can save around 30% of water used for flushing toilets and cut household water use by up to 8% in new build

• Waterless urinals can be achieved without the use of special chemicals or consumables.

• Waterless and vacuum toilets. These are not a simple direct replacement for the WC. For rural and suburban eco-houses and remote toilet blocks they can represent a best available technology but their widespread use is not considered likely in the UK at present.

• Water-saver showers. Bath shape can also be varied to encourage water saving. • Spray taps – when used in commercial washrooms these can offer around 80%

reduction in flow rate. • Supply restrictor valves. Flow restriction and pressure and flow regulation can help to

minimise water use. Products are low cost and readily available. • Plumbing systems - minimising amount of piping between boiler/hot water tank and

tap can reduce the need to “run” the water; thermal store combi boilers. • Proximity detection shut off for urinals and WCs, and composting toilets. Water efficiency in gardens/communal greenspace: • Utilisation of rainwater harvesting techniques (e.g. incorporating water butts) which

can provide sufficient water for all but the largest gardens • Choice of plant species. For example, Mediterranean species are suitable for poor,

free-draining soils. • Direct greywater use (e.g. systems to use greywater from baths and showers diverted

from upstairs bathrooms to a hose when needed) could provide water when extra water is required in summer. In dry parts of the UK, the potential for direct greywater irrigation is considerable.

Installation of water meters: • Due to climate change the supply of water is likely to decrease as rainfall becomes

more seasonal, while the demand increases due to hotter summers, population and household growth and increased levels of use of consumer durables like dishwashers. There will also be more demand for water in gardens and for bathing. Saving water can be promoted by installing water meters. By paying according to use, consumers have an incentive to limit their water consumption. All new houses will automatically be fitted with meters, but for flats this may not be the case, so should be encouraged.

Water reuse Rainwater use systems (other than garden butts): • A system that collects rainwater from where it falls, treats and stores it, then

distributes it for use rather than allowing it to drain away. This includes water collected within the boundaries of a property, including from roofs and surrounding surfaces such as areas of hardstanding and pervious paving. Rainwater, correctly collected and stored, can be used to flush toilets, clean clothes and water the garden,

which together account for more than half of domestic water use. Rainwater use systems can range from basic water butts in back-gardens to more technical systems stored in roof spaces or centralised reservoirs/tanks in larger developments. A large number of products is now available, mainly from Germany, where commercial systems are currently installed at a rate of around 50,000 per year.

• Rainwater use systems are likely to provide useful savings of mains water at a reasonable cost. There are no legislative barriers to the use of rainwater systems in the UK. The main barriers to the use of rainwater as identified in “Buildings that save water” projects are:

• Unproven cost to benefit ratio: • Difficulties in operation and maintenance • Water quality standards and public health • Lack of guidance on system • A lack of legislation in support of system

• Costs of installing a typical rainwater harvesting system in new buildings are relatively low (£1000-£2000 for a typical family home). There are likely to be higher costs for retrofitting systems into buildings and lower costs per dwelling for larger developments. The cost of the system has to be balanced against the long term savings of such a system.

• Benefits are that the system is cheap to operate and maintain, it is generally able to supply 50% of household needs, it can be used for residential or commercial premises and reduces surface water run off. However, as best practice WC and washing machine volumes continue to drop this figure will be subject to revision in future in new-build.

• A wide range of commercial systems are available. • There is a low risk of water quality, given that the systems are designed to supply WC

flush, garden and car and laundry.

Water recycling Greywater use systems: • An above- or below-ground system that collects, stores, treats and disinfects

greywater for use as reclaimed water in and around properties. Grey water systems make a second use of the waste water from baths, showers and washbasins, for example to flush toilets. Manufacturers typically claim water savings of around 30-40% i.e. it is assumed that all WC water is supplied by grey water.

• The disadvantage of the system is the more complex and robust system operation and water treatment required than for rainwater systems, with higher maintenance demands, greater costs and a longer term pay-back time. Overall the risks to health are low when such systems are fully functional. In the event of malfunction however, greywater poses a greater risk than rainwater due to initial quality and storage conditions which can lead to proliferation of bacteria. The lack of a fit-and-forget system dealing with issues of odour, colour and turbidity still may dissuade people from taking up the systems.

• In commercial buildings it is unlikely that greywater arising will be sufficient to fully meet the demand for toilet flushing or other water uses.

Combined systems: • It is also possible to combine rainwater and greywater to provide a viable water

source. If the rainwater and greywater are combined prior to treatment or disinfection, it will be necessary to treat the water as greywater. Keeping the two sources separate and/or combining the reclaimed water prior to use is another option.

APPENDIX 4B

APPLICABILITY OF MEASURES TO RESPOND TO PRESSURES ON WATER RESOURCES FOR DIFFERENT DEVELOPMENT TYPES

41. The table below indicates the types of development in which different types of measures to improve water efficiency are applicable5.

Table A4.1: Suitability of water efficiency measures for different building types

Method of water efficiency Type of development

Dual flush and low flush cisterns Residentiala and commercialb

Water efficient white goods: washing machines and dishwashers

Residential and commercial

Low use showerheads and taps, pipe run and lagging Residential and commercial

Urinal flushing controls Commercial

Rainwater and greywater systems Residential and commercial (for further discussion on characteristics for different building types see Table A4.2 below)

Drought tolerant gardens Residential and commercial

a Includes houses (detached, semi detached, terraced) and multi-residential (blocks of flats, hotels hostels boarding schools, residential homes) b Includes offices, factories, retail Source: Adapted from water efficiency checklist included in Water Efficiency in New Development, September 2004. East of England Sustainable Development Round Table and Environment Agency.

42. Table A4.2 below provides a summary of the suitability and type of rainwater and greywater systems appropriate for different building types.

Table A4.2: Installation and operation factors for rainwater and greywater systems for different building types

Building Type Houses (detached, semi detached, terraced)

Multi-residential (blocks of flats, hotels hostels boarding schools, residential

Commercial (offices, factories, retail)

5 Information in this appendix is drawn from Water Efficiency in New Development, September 2004. East of England Sustainable Development Round Table and Environment Agency.

homes)

Size/complexity of system

Simple Small system

Larger complex systems

Discrete systems associated with individual toilet facilities or groups of facilities

Sources of water

Rainwater: potential depends on available space for storage and catchment. Greywater: Arisings can match WC requirements (however, some researchers suggest that greywater use at the single household level with current technologies is not recommended due to poor cost effectiveness, reliability and unreliable water savings)6.

Rainwater : Potential depends upon building topography Available space for storage Greywater: arisings can match WC requirements

Rainwater: Large potential due to large roof area of buildings Greywater: arisings may be relatively low

Rainwater potential may be limited to some degree in the case of individual residential buildings because of the small roof area and available space for storage. It is therefore considered most appropriate for multi-residential buildings such as flats (provided the catchments surface to dwellings ratio is high enough), hotels and offices and factories with large roof areas and available space for storage.

Collection and distribution

Collection points close to points of use

Dispersed collection points and points of use with centralised processing

Dependant on site

Design and installation

Proprietary Solutions with possible DIY fitting of main system parts

Professionally designed and installed

Professionally designed and installed

Application Relatively easy to retrofit

Easily integrated into new build. Difficult to retrofit

Ease of application depends on building topography

6 Water Conservation Products: A preliminary review. Watersave Network. May 2002.

Compliance with Legislation

Water Supply (Water Fittings) Regulations (1999), Building Regulations.

Health & Safety Regs Water Supply (Water Fittings) Regs (1999) Building Regs

Health and safety Regs Water Supply (Water Fittings ) Regs (1999) Building Regs

Financial benefits

Direct financial benefit for metered customers

Financial benefits for customers. Reduced demand primarily through use of water efficient appliances.

Direct financial benefit for building operators. Benefits for factories will vary depending on the processes used.

Maintenance Routine tasks Regular maintenance by trained personnel

Regular maintenance by trained personnel

Performance monitoring

Minimal performance monitoring required

Regular performance monitoring required

Regular performance monitoring required

Source: Water Efficiency in Development, September 2004. Environment Agency & Sustainable Development Round Table for the East of England

APPENDIX 5A

MENU OF ADAPTATION OPTIONS TO RESPOND TO FLOOD RISK The suitability of the following measures to respond to flood risk should be considered when preparing LDF policy/making development control decisions: Development specific measures

Development zoning Careful planning of development layouts may allow flood risk to be managed without the need for the construction of physical mitigation measures. Zoning techniques are based on the idea of locating less vulnerable uses in parts of the development site at higher risk of flooding, such as amenity/ecological features, car parks and some access roads (whilst ensuring access is available during flood events), and locating buildings above the flood level. Some built development may also be permissible within the floodplain, for example, some industrial and commercial premises, if they can be designed to withstand the impact of flooding.

Provision of safe access When considering any of the possible adaptation measures to adapt to flood risk, it is essential that consideration is given to safe access. For example, when zoning development, raising floor levels or building on raised land, it is important that safe access routes are built in to provide escape routes, for example, timber walkways.

Raising floor levels Raising the floor level of buildings to above flood defence level can reduce flood risk. Car parking and utility areas may be located at lower levels. Ideally this will be achieved by appropriate zoning or land raising. However, in some cases it may be feasible to design the development so that the ground floor is allowed to flood, provided that the use of the ground floor is such that flooding would be acceptable. It is essential that safe access to enable residents to exit properties in times of flood is also built into properties.

Land raising Raising land levels from existing ground levels to a level above the flood defence level, and constructing the development on this ground is a method frequently used to manage flood risk. A number of criteria must be met to ensure land raising is safe and does not preclude safe access during a flood and does not increase flood risk elsewhere. For further details refer to Development and flood risk: guidance for the construction industry, CIRIA C624, 2004.

Flood warning The majority of new developments should be designed so that flood warning is not a necessary part of the development design. However, the use of warning signs and marked evacuation routes are recommended in areas subject to flood risk.

Flood proofing

Further detail is provided below

Flood proofing is a technique whereby buildings are designed to withstand the effects of flooding. Flood proofing is unlikely to be suitable as the only mitigation measure for most new residential developments, but may be suitable in certain circumstances. Further guidance on the suitability and methods of flood proofing may be found in Development and flood risk: guidance for the construction industry, CIRIA C624, 2004.

Design of channel and When designing new development consideration should also be given to

hydraulic structures the implications on upstream water levels due to encroachment into the flood plain. If impacts are found to be unsuitable, modifications to existing flood channels to offset the impacts of development may be an option. Consideration should also be given to the correct design of bridge/culvert crossings. Further guidance on the issues and requirements surrounding the design of channel and hydraulic structures is provided in Development and flood risk: guidance for the construction industry, CIRIA C624, 2004.

Flood defences In principle, flood defences can be constructed to protect a development from the design flood. However, this option should be avoided where possible, in line with Government policy set out in PPG25.

Developer contributions to strategic flood risk management

In some situations it may be possible for the developer of a site to contribute towards a planned flood alleviation scheme that is part of the long-term plan for strategic flood risk management of an area, rather than provide site specific mitigation measures.

Compensatory flood storage

Compensatory flood storage works are required where the proposed development would otherwise reduce the available volume of flood storage. Further guidance on the issues and requirements surrounding this form of mitigation is provided in Development and flood risk: guidance for the construction industry, CIRIA C624, 2004.

Management of development runoff (SUDS type measures)

Further detail is provided below

Careful design of runoff from development sites is required, both to manage the flood risk posed on the site due to runoff and to avoid an increase in flood risk downstream of the site. Sustainable Drainage Systems (SUDS) techniques are preferred to traditional means (such as oversized pipes, tanks, etc.) as they attempt to reproduce natural systems. The primary function of SUDS is to manage runoff, but SUDS may also help to manage water quality, and can have dual benefits, for example, through providing landscape and ecological features. It should be noted that SUDS are not just soft-engineering techniques, but might include tanks, pipes and other ‘hard engineering’ accessories.

Pumping Where a development is to be protected by an existing or a new flood defence, pumping may be required to drain the low-lying area behind the defence, during periods when water levels within the receiving watercourse are higher than the maximum allowable water level within the development. Wherever possible, development designs that are reliant on pumping should be avoided as they have ongoing maintenance and running costs, and the development will be vulnerable should the pumping station fail.

Source: Information adapted from Development and flood risk: guidance for the construction industry. CIRIA C624, 2004. N.b. Appendix A3 of the CIRIA document provides further detail on the range of adaptation options available, and includes a number of checklists to determine the acceptability of these measures in a given development.

Further detail: Adaptation options to increase built structure resilience to flooding (flood proofing)

43. CIRIA document C624 Development and flood risk: guidance for the construction industry notes that flood proofing methods fall into two main categories: dry proofing methods which are designed to keep water out (e.g. design of floors and walls to prevent seepage), and wet proofing methods designed to improve the ability of the

property to withstand the effects of flooding once water has entered the building (e.g. use of flood-resistant fittings). A range of measures are summarised in Box A5.1. Increasingly, modern methods of construction (MMC) are being used in the construction of new development. Box A5.2 summarises some of the implications of this development for ensuring new development is resilient to flood risk.

Box A5.1: Adaptation options to increase built structure resilience to flooding Walls and floors • Water-proof membranes for brick work - A variety of water-resistant paints and coatings

(or tanking) are available that can help prevent floodwater soaking into the external face of the wall, thus allowing the wall to dry out more quickly. Specialist advice must always be obtained to ensure that the most appropriate system is chosen for the property. Coatings should be applied to 500mm above the maximum expected level of flooding. Any measures to improve water resistance must be compatible with the existing wall materials and must allow adequate water vapour transmission to avoid trapping moisture within the wall.

• Avoid cavity filling where possible and when filled leave a 50mm air gap. Use closed cell

insulation rather than mineral insulation within internal partition walls. Closed cell insulation is more likely to survive a flood without having to be replaced.

• Flood resistant wall covering - The ground floors and basements of buildings at risk of

flooding should utilise more water resistant coverings such as internal water-resistant render and lime based plaster finishes. Ceramic tiles with water-proof grouting, and hydraulic lime coatings.

• Solid concrete floors - Solid concrete floors are preferable to suspended floor construction as

they can provide an effective seal against water rising up through the floor, provided they are adequately designed. Solid concrete floors generally suffer less damage than suspended floors and are less expensive and faster to restore following exposure to floodwater.

• Treated Timber Floorboards - Use treated timber floorboards and joists rather than

chipboard as chipboard has to be replaced if there is any chance of contamination. Other treated floorboards are more resilient to flood. Treated timber is also more water resistant/repellent. The timber is less likely to absorb water, enabling the floor to dry out more quickly and be more resistant to rot or distortion.

• Radon and landfill gas barriers (also applicable to flood damage) - In many parts of the

country ground floors need to be sealed to prevent naturally occurring radon gas, or methane or carbon dioxide from landfill sites, from seeping into the building though the ground. For solid concrete floors the radon barrier also serves as the damp proof membrane beneath the concrete slab. For suspended timber floors polythene membranes are installed below ground level.

Fixtures and fittings • Raise circuitry levels above expected high water levels. Move electrics to at least one meter

above floor (or well above likely flood level) with cables dropping from first-floor level distribution down to power outlets at high level on wall. Install electrical circuits, wires and other associated infrastructure at a high level in walls so as to avoid flooding damage. Also move service meters to at least one metre above floor level (or well above likely flood level) and place them in plastic housings.

• Work surfaces - Kitchen work surfaces should be built so as to be able to withstand the weight

of white goods being stored on them during flooding episodes, so as to raise appliances above flood levels.

• Non-return valves - Flooding can create blockages in drains and sewers which can lead to the backflow of sewage into properties through low level drain gulleys, toilets, and washing machine outlets. Backflow through drains is particularly likely where floodwater is prevented from entering the property using temporary barriers and where the external flooding depth outside is above the internal level of the drain entry points. Such flooding can be effectively controlled by installing non-return valves, often called anti-flooding devices, within the private sewer of a property upstream of the public sewerage system. These devices are typically between 0.5 to 1 metre in length and are installed in-line within an inspection chamber to allow access for maintenance. They are designed for installation within gravity sewers or drains and normally use flap gates to prevent backflow.

• Trap doors – Fit trap doors in the roofs of houses to create an escape route. Temporary barriers • Air Brick barriers - A number of plastic covers are available that can be fixed over airbricks

and other vents in external walls. Such covers are usually clipped into a frame fixed around the airbrick or vent opening. It is very important to remove such barriers once floodwaters have subsided.

• Sandbags - As well as manufactured flood barrier products, sandbags can be effective in

reducing the ingress of floodwater into buildings and are still widely used. The Environment Agency has produced separate advice on how sandbags should be used, and on alternatives such as earth filled bags. Details can be found within the Agency’s leaflet ‘Damage Limitation’ and on their Floodline website. The leaflet also gives advice on how to make home-made flood boards.

• Water proof building skirt - As well as flood barriers for doors, windows and airbricks, more

advanced systems are available for enclosing the bottom 600mm to 900mm of buildings with flexible plastic skirting to prevent the ingress of floodwater. The plastic skirting can be housed in underground ducts and then lifted up to protect the walls in advance of a flood. Such methods are likely to be expensive to install but could be beneficial in certain circumstances, such as for detached properties that are regularly flooded.

• Barriers for external doors - Barriers for external doors usually take the form of plastic or

aluminium flood boards that can be quickly installed across a doorway in advance of floodwaters arriving. The flood boards normally slide into a frame attached around the doorframe to provide a watertight seal. After the floodwater has receded the boards can then be removed, cleaned and stored for re-use.

• Barriers for windows and patio doors - Barriers for windows and patio doors are similar to

those for external doors. Flood boards, or beams for wider openings, are normally dropped into a frame attached around the opening. Such systems can also be used for shop windows and garage doors.

Flood proofing gardens • A range of measures can be built into garden design to minimise potential for flood damage. For

example, ensuring adequate drainage, raising beds, planting plants that like wet conditions, paving with a rough finish to ensure it is not slippery and installing any electrics at least a metre off the ground.

Box A5.2: Modern methods of construction and flood resilience

The Government’s Sustainable Communities Plan identifies Modern Methods of Construction (MMC), as one means to boost housing supply. Such methods include off site manufacture, use of timber and light gauge steel frame and prefabrication, which can be more time and cost-efficient than

traditional construction techniques. However, as noted by the Association of British Insurers, many of these construction techniques are largely untested, and there is currently little information about their long-term resilience to flooding and other perils (e.g., driving rain, water ingress, fire, wind). The Council of Mortgage lenders is similarly concerned and is working with BRE over a proposed new certification standard for MMC properties that should address many concerns this organisation has.

Further detail: Adaptation options to manage development runoff 44. CIRIA’s publication Sustainable Drainage Systems: Hydraulic, structural and water quality

advice notes that sustainable drainage systems (SUDS) are increasingly being used to mitigate the flows and pollution from runoff. The philosophy of SUDS is to replicate as closely as possible the natural drainage from a site before development and to treat runoff to remove pollutants, so reducing the impact on receiving watercourses. This requires a reduction in the rate and volume of runoff from developments, combined with treatment to remove pollutants as close to the source as possible. They can also provide other environmental benefits such as wildlife habitat, improved aesthetics or community resources. The CIRIA advice notes a range of benefits from using SUDS as opposed to conventional drainage systems:

• Lowering peak flows to watercourses or sewers, thereby reducing the risk of flooding downstream.

• Reducing volumes and frequency of water flowing directly from developed sites to watercourses or sewers, to replicate natural land drainage and reduce flood risk.

• Improving water quality over conventional surface water sewers by removing pollutants from sources such as cleaning activities (vehicles, windows), wear from tyres, oil leaks from vehicles or atmospheric fallout from combustion (in rural areas this can include runoff from fields where fertilisers and biocides are used).

• Improving amenity through the provision of features such as wildlife habitat.

• Reducing the number of times that combined sewer overflows operate and discharge polluted water to watercourses.

• Replicating natural drainage patterns so that changes to base flows are minmised.

• Finally, by increasing base flow to watercourses (through slow release of water).

45. Consideration should be given to SUDS techniques at an early stage of the development design process, as this can influence site masterplanning. A summary of SUDS techniques is provided in Box A5.4. There is a wealth of information available on SUDS, which is signposted in Appendix 7.

46. A number of issues should be borne in mind when considering the application of SUDS techniques in any development. Some key considerations are summarised in Box A5.3.

Box A5.3: Issues to consider when incorporating SUDS into a development

• The role of early discussion with stakeholders.

• Ground and groundwater considerations.

• Drainage impact assessment.

• Interaction with foul water sewers – where there are no separate foul and surface water sewers on a development, Section 106 of the Water Industry Act 1991 effectively permits the discharge of surface water form SUDS to foul and combined sewers. This is unacceptable, as unplanned surface water drainage connections may exacerbate the risk of flooding where sewers had been designed to accept only foul flows (or where combined sewers are running at capacity). Surface water drainage systems should be dealt with sustainably through SUDS techniques or connected correctly to surface water sewers to avoid the risk of sewage-related flooding.

• SUDS design and performance considerations.

• Long-term adoption and maintenance requirements (discussed further in Section 7 of the Toolkit).

• Types of measures appropriate for different types of development – a key perceptual issue is that SUDS aren’t applicable due to a lack of space. However, it is possible to ‘make space work’ for example through building SUDS into driveways of buildings or through use of green roofs in urban areas. Some measures, such as swales, can range from large landscape features, to much smaller features of only a few feet in width. Appendix 5B includes further information on types of measures which might be suitable for different development types.

• Legal issues relating to:

• Water quality – it is essential that all drainage systems, including SUDS, comply with environmental legislation.

• Highway authorities’ right to discharge – highway authorities have a responsibility to ensure that discharges are not causing pollution and it is for them to determine how pollution control is carried out.

• Waste management – sedimentation is likely to occur in SUDS. There will be a requirement to remove deposited sediment periodically to ensure that the system continues to operate efficiently and to control the risk of pollution. Where sediment waste arising from SUDS maintenance is removed off-site, it must be treated as controlled waste and are subject to control under the Waste Management Licensing Regime. The Special Waste Regulations (1996) may also be relevant.

This is a summary of some of the issues to consider. For further information refer to the references listed in Appendix 7 and in particular:

• Interim Code of Practice for Sustainable Drainage Systems by the National SUDS Working Group (July 2004) (see Box 7.1 in the Toolkit). This provides an overview of the SUDS approach, the role of the planning systems, legal issues to take into account when planning for SUDS, adoption and maintenance and design considerations, and model agreements.

• Sustainable Drainage Systems: Hydraulic, structural and water quality advice. CIRIA 2004 (CIRIA document C609).

Box A5.4: SUDS measures7

• Pervious pavements - Infiltrateable surfaces which allow infiltration of rainwater into the underlying construction or soil. The surface material itself can be porous (made up of a matrix of interlinked pores that allow ingress of water), or water can enter the sub-base through joints and spaces between impermeable blocks. Runoff is stored and conveyed through the sub-base construction. Permeable surfaces remove the need for conventional drainage such as gullies and manholes. In areas where ground conditions are not conducive to water percolation, ‘egg carton’ type material can be used to line an excavation zone to improve water storage capacity.

• Green roofs - Planted roof areas where the vegetated area provides a degree of retention and treatment of water and promotes evapotranspiration. Then extent to which they can help minimise runoff is debatable, but green roofs also have other benefits including insulating against heat gains and providing useable outdoor space.

• Bioretention – Shallow depressed landscaped areas that are underdrained and rely on enhanced

vegetation and filtration to remove pollution and reduce runoff volumes.

• Filtration techniques – Constructed tank or lagoon whose base contains a filter material through which water percolates, to promote pollution removal.

• Grassed filter strips – Wide, relatively gently sloping areas of grass or other dense vegentation that treat runoff from adjacent areas.

• Swales - shallow linear channels that are designed to convey runoff and remove pollutants. They have significant pollutant-removal potential and can be designed to allow infiltration under appropriate conditions. They are particularly suitable for diffuse collection of surface water runoff from small residential or commercial developments, paved areas and roads. Swales can also be used for runoff attenuation, treatment (by settlement or filtration thought the vegetation) and disposal (by allowing infiltration through the base of the swale).

• Infiltration devices – Takes runoff, temporarily stores it and allows it to percolate into the

ground. Infiltration devices include soakaways and infiltration trenches. Infiltration can also be used to release water from below other SUDS techniques such as pervious pavements.

• Filter Drains - A filter drain comprises a perforated or porous pipe in a trench surrounded with a suitable filter material, granular material or lightweight aggregate fill. The fill may be exposed at ground surface or covered with turf, topsoil or other suitable capping. Filter drains collect runoff from the edge of paved areas, then store and convey it.

• Infiltration Basins - Infiltration basins are depressions which store surface water runoff and

allow it to gradually infiltrate through the soil of the basin floor. An emergency overflow can be provided for extreme rainfall events, when the storage capacity of the basin in exceeded. Differs from swales as swales are linear features whilst infiltration basins may take any shape.

• Extended Detention Basins - Vegetated depressions formed below the surrounding ground

level. They are dry except during and immediately following storm events. Detention basins only provide flood storage to attenuate flows. Extending the detention times improves water quality by permitting the settlement of coarse silts.

7 This list of SUDS measures is based on those measures covered in Sustainable Drainage Systems: Hydraulic, structural and water quality advice. CIRIA 2004 (CIRIA document C609)

• Wet Ponds - Permanently wet ponds with rooted and aquatic vegetation – mainly around the edge. The retention time of several days provide better settlement conditions than offered by extended detention ponds and provides a degree of biological treatment. Baffles may be used within the design of retention ponds in the form of islands, promontories and submerged shoals. Such baffles provide visual interest and variation in habitat.

• Stormwater Wetlands - Reed beds and wetlands will hold water when it rains, providing storage for water run off. They may be designed to run dry at some times of the year. Wetlands may comprise relatively shallow ponds and marshland areas that are covered almost entirely in aquatic vegetation. Wetland vegetation is well suited for the biological treatment and removal or dissolved contaminants and nutrients, and the use of wetlands for water and wastewater treatment is well documented.

• On-/off-line storage – Storage of runoff in underground tanks or other structures such as

oversized pipes. • Minimising Directly Connected Areas - Hard paving and roofed areas can be drained onto

unpaved areas. Driveways and footpaths can be drained onto surrounding lawns. • Pipes and accessories – A series of conduits and their accessories normally laid underground

that convey surface water to a suitable location for treatment and/or disposal. (Although sustainable, these techniques should be considered where other SUDS techniques are not practicable).

Illustrations of SUDS measures Permeable paving

SUDS permeable paving at Sanders World garden centre, Somerset

SUDS permeable paving cross-section

SUDS roadside filter drain Infiltration trench

SUDS infiltration trench cross sectional diagram

Swale Infiltration basin

Housing estate roadside swale, Dundee

Cross section diagram of a SUDS infiltration basin

SUDS pond

SUDS Pond, housing development, Bicester

SUDS pond cross section diagram Source: www.environment-agency.gov.uk

APPENDIX 5B

APPLICABILITY OF MEASURES TO RESPOND TO FLOOD RISK FOR DIFFERENT DEVELOPMENT TYPES

47. Appendix 5A identifies a range of measures to address flood risk. Many of these will be applicable to a range of development types.

Table A5.1: Applicability of measures to respond to flood risk for different development types

Measure Applicability to different development types*

Development zoning Applicable to mixed use developments and developments containing a range of land uses (greenspace, car parks, access roads). Industrial and commercial premises, in some cases, may be located within flood risk zones. These may be acceptable if they can be designed to withstand the impact of flooding.

Provision of safe access Consider for all development types (i.e. commercial and residential).

Raising floor levels May be applicable for commercial and residential developments.

Land raising May be applicable for commercial and residential developments.

Flood warning May be applicable for commercial and residential developments.

Flood proofing Flood proofing may be appropriate for:

• Industrial developments where temporary disruption is acceptable

• Developments which are designed with ground floors that can flood

• Developments where the use of an existing building is to be changed

• Developments which include basements that are at risk of flooding

• Developments which are located on the edge of the flood risk zone, such that flooding depths are likely to be very low and access may be maintained during a flood event

• Developments which will not flood during the design flood event, but which may be flooded by an extreme flood event.

Design of channel and hydraulic structures

May be applicable for commercial and residential developments.

Flood defences May be applicable for commercial and residential developments.

Developer contributions to strategic flood risk management

May be applicable for developers of commercial and residential developments.

Compensatory flood storage

May be applicable for commercial and residential developments.

Management of development runoff (SUDS type measures)

See further detail below.

Pumping May be applicable for commercial and residential developments.

*n.b. further advice on key considerations when determining the appropriateness of different measures is provided in CIRIA C624 Development and flood risk – guidance for the construction industry

Applicability of SUDS to respond to flood risk for different development types

48. CIRIA C609 Sustainable Drainage Systems: Hydraulic, structural and water quality advice provides technical knowledge on the appropriate approach to the design and construction of SUDS. It provides considerable advice on identifying appropriate SUDS measures for different developments, based on a wide range of criteria, including a range of decision making tools and checklists to help the process. The text presented here provides an overview of some of the issues which determine which techniques may be suitable for different developments, but it is strongly advised that planners, developers and other stakeholders involved in development design consult the technical advice provided in the CIRIA document. Several key issues in terms of development types are discussed in the boxes below.

Box A5.4 SUDS in urban developments

There is no reason why SUDS cannot be incorporated into urban developments where space Is restricted. To achieve this, the SUDS design should be integrated into the site layout at the feasibility stage. Allocating space for SUDS has been successfully achieved in Scotland, owing to the production of innovative solutions for cramped sites. In these situations it is helpful to use SUDS features such as proprietary modular treatment systems and green roofs, or to implement rainwater harvesting. It should be remembered that public open space can be used for storing runoff in extreme storm events.

Source: Section 1.2 CIRIA C609 Sustainable Drainage Systems: Hydraulic, structural and water quality

Box A5.5 SUDS on brownfield sites

The main consideration for SUDS on brownfield sites is whether ground contamination is present(not that not all brownfield sites are contaminated). Implementing a SUDS scheme should not be difficult if care is taken in the design to avoid mobilizing pollution into the surface water or groundwater. Indeed, the use of shallow SUDS should limit the need for the deeper and oversized excavations and lining commonly associated with conventional drainage on contaminated sites. The use of piped systems can also provide sub-surface off-site pollution pathways, via the trench backfill, that may be removed by the use of SUDS. CIRIA document C609 provides further advice on site investigation, and factors to address in terms of SUDS on brownfiled sites.


Box A5.6 Retrofitting SUDS

SUDS techniques can be retrofitted to existing sites to reduce the risk of flooding in receiving waters or to reduce pollutant loadings in runoff. It is often easier to retrofit an individual technique, rather than provide a ‘management train’ (a hierarchy of techniques, first seeking to prevent runoff and pollution, down to management of runoff at the ‘regional’ level from several

sites, typically in a detention pond or wetland). Conventional SUDS design usually follows pre-determined design criteria, but for retrofit the design process works in reverse. Starting with a set of existing site constraints, the designer should determine the best sotrmwater control or treatment obtainable, even though this may not fully comply with current design standards. The opportunity to retrofit is likely to be limited to situations where sites are being refurbished or where the existing drainage system has failed and requires replacement.


49. The CIRIA document includes a selection matrix for SUDS techniques setting out suitability and ratings in terms of the following criteria:

• Treatment suitability (pollutant removal).

• Hydrological (water quantity control, groundwater recharge, flow rate control).

• Land use (dense urban developments car parks, roads, housing, stormwater hotspots).

• Suggested drainage sub-catchment area.

• Site slope.

• Space required.

• Soil considerations.

• Roof slope.

• Economics and maintenance (life-span, initial cost, maintenance burden).

• Community and environment (safety, pond premium8, aesthetics, wildlife habitat, community acceptance).

50. The document also provides more detailed guidance on design issues and suitable applications of each SUDS technique in Section 9. Table A5.2 below presents an extract of ‘site based’ criteria from the selection matrix for SUDS techniques in CIRIA document C609.

Table A5.2: Summary of ‘site based’ criteria for selecting SUDS techniques

Technique Dense urban developments

Car parks Roads Housing Space required

Pervious pavements

Yes Yes Yes Yes No additional space beyond car parking requirements

Green roofs Yes No No Yes No additional space

Bioretention Possibly Yes Yes Yes Minimal to large, depending on

8 Evidence from the USA has shown there is a price premium on waterfront properties where SUDS ponds are incorporated into new developments.

Technique Dense urban developments

Car parks Roads Housing Space required existing landscaping

Filtration technique

Yes Yes Yes Yes Minimal to moderate

Grassed filter strips

No Yes Yes Possibly Moderate to high

Swales Difficult Yes Yes Yes, if located outside gardens

Moderate

Infiltration devices

Possiblya Yes Yes Yes Minimal

Filter drains Possibly Yes Yes Yes Minimal Infiltration basin

No Yes Yes Yes Substantial

Extended detention basin


Wet ponds No Yes Yes Yes Substantial Stormwater wetlands


On-/off-line storage

Yes Yes Yes Yes Minimal (can be put below most site areas, including buildings)

a if it can be located more than 5 m from buildings Source: Extract from Tables A1a, b & c from Appendix A1 Decision-making for SUDS techniques from CIRIA C609 Sustainable drainage systems: Hydraulic, structural and water quality advice.

APPENDIX 6

FURTHER SOURCES OF INFORMATION

Climate change in the South East • Arkell, B., Darch, G., Wilson, E. and Piper, J. 2004. South East Climate Threats and

Opportunities Research Study (SECTORS). Technical Report for the South East England Development Agency, Guildford.

• Wade, S., Hossell, J., Hough, M. and Fenn, C. (Eds.) 1999. The Impacts of Climate Change in the South East: Technical Report, WS Atkins, Epsom, 94pp.

• Hulme, M., Jenkins, G.J., Lu, X., Turnpenny, J.R., Mitchell, T.D., Jones, R.G., Lowe, J., Murphy, J.M., Hassell, D., Boorman, P., McDonald, R. and Hill, S. 2002. Climate Change Scenarios for the UK: the UKCIP02 Scientific Report, Tyndall Centre for Climate Change Research, School of Environmental Sciences, University of East Anglia, Norwich, UK. 120pp.

Identifying appropriate adaptation responses • The Planning Response to Climate Change. Advice on Better Practice. ODPM 2004

• Hulme, M., Jenkins, G.J., Lu, X., Turnpenny, J.R., Mitchell, T.D., Jones, R.G., Lowe, J., Murphy, J.M., Hassell, D., Boorman, P., McDonald, R. and Hill, S. 2002. Climate Change Scenarios for the UK: the UKCIP02 Scientific Report, Tyndall Centre for Climate Change Research, School of Environmental Sciences, University of East Anglia, Norwich, UK. 120pp.

• UKCIP Risk and uncertainty in decision making

• CIRIA 624 Development and flood risk guidance for the construction industry

The role of the planning system • Planning Policy Statement 1: Delivering Sustainable Development. ODPM, 2005.

• Planning Policy Statement 11: Regional Spatial Strategies. ODPM, 2004.

• Planning Policy Statement 12: Local Development Frameworks. ODPM, 2004.

• Planning Policy Guidance 25: Development and Flood Risk. ODPM, 2001 (under review).

• Planning Policy Guidance 3: Housing. ODPM, 2000.

• Planning Policy Guidance 20: Coastal Planning. ODPM, 2000.

• Annex 2 of PPG14 Development on Unstable Land (relevant, but does not specifically refer to climate change and subsidence)

• The planning response to climate change: Advice on better practice. ODPM 2004.

• Strategic Environmental Assessment and Climate Change: Guidance for Practitioners. CCW, EA, EN, UKCIP, Levett-Therivel, GAG Consultants, Environmental Change Institute. May 2004.

Writing policies for LDFs • Policies for Spatial Plans: consultation draft. Planning Officers’ Society August 2004

• The planning response to climate change: Advice on better practice. ODPM 2004

• A joint Agency (Environment Agency, English Nature, Countryside Agency and English Heritage) policy document entitled Environmental Quality in Spatial Planning forthcoming. This will provide broad guidance to RPBs and LPAs on developing policies for RSSs/LDFs to ensure they cover the full range of environmental issues)

Climate-sensitive development checklists/wider sustainable development checklists • The planning response to climate change: Advice on better practice. ODPM 2004

(specific section on a climate-sensitive development checklist)

• A Consultation Document: Adapting to Climate Change: A Checklist for Development: Guidance on Designing Developments in a Changing Climate January 2005. Prepared by GOL/GLA/UKCIP/CIRIA(?)/SE Climate Change Partnership/East of England SD Roundtable

• Climate Neutral Practice Note, Woking Borough Council

• Sustainability Checklist for Developments in the South East, South East England Development Agency, 2004

• BREEAM Offices 2004 Design & Procurement Assessment Prediction Checklist, Building Research Establishment, 2004

• ECOHOMES 2003 Rating Prediction Checklist, Building Research Establishment, 2003

General information on adaptation options • UKCIP Briefing Note: Climate Change Impacts on Buildings

• A review of recent and current initiatives on climate change and its impact on the built environment: Impact, Effectiveness and Recommendations. CRISP Consultancy Commission, R. Lowe 2002

• Potential UK adaptation strategies for climate change, ERM 2002

• A Consultation Document: Adapting to Climate Change: a Checklist for Development. January 2005.

• South East Climate Threats and Opportunities Research Study, SECTORS, Technical Report for the South East England Development Agency, Arkell, B., Darch, G., Wilson, E. and Piper, J. 2004.

• Potential implications of climate change in the built environment, Hilary M Graves and Mark C Phillipson, FBE 2000

• Climate Neutral Development, a good practice guide. Woking Borough Council

• Kent Design, a guide to sustainable development. Kent Association of Local Authorities, 2000

• Living with Climate Change in the East of England. Land Use Consultants in association with CAG Consultants and SQW Limited, 2003.

• Climate change and UK housebuilding: perceptions, impacts and adaptive capacity, SPRU & Tyndall Centre for Climate Change Research

• Meeting the Challenge of Climate change, Summary of the SECTORS Project. SEEDA 2004

• EcoHomes – The environmental rating for homes: The Guidance. BRE 2003

• SEEDA Sustainable Development Checklist

Water management adaptation options: responding to pressures on water resources • Water Conservation Products, A Preliminary Review. Watersave Network. Elemental

Solutions (2002)

• Model agreements for sustainable water management systems: Model agreement for rainwater and greywater use systems. CIRIA C626 (2004)

• SUDS Hydraulic, structural and water quality advice (CIRIA C609) (this document also addresses rainwater harvesting) (2004)

• Conserving water in buildings. Environment Agency (this series of leaflets provides references to more technical documents on specific water efficiency measures)

• Envirowise: www.envirowise.gov.uk

• The Market Transformation programme www.mtprog.com

• Environment Agency Fact Cards and Suppliers List: Tel: 01903 832275 www.environment-agency.gov.uk/savewater

• Enhanced Capital Allowance www.eca-water.gov.uk

• The Hyde Hall Garden, Chelmsford www.rhs.org.uk/gardens/hydehall

• Climate neutral development a good practice guide http://www.woking.gov.uk/council/planning/publications/climateneutral2/summary.pdf

• Supplementary Planning Guidance on Sustainable Buildings. Westminster City Council working in partnership with Entec UK Ltd. March 2003 http://www.westminster.gov.uk/environment/planning/sitesandprojectspolicies/spg.cfm

• Water Efficiency in New Development, September 2004. East of England Sustainable Development Round Table and Environment Agency. http://www.sustainability-east.com/Reports/WaterEfficiencyInDevelopment.pdf

• Mid Kent Water and Kent County Council will be publishing design guidance on sustainable water use in spring 2005.

Water management adaptation options: responding to flood risk • National Standing Advice to Local planning Authorities for Planning Applications –

Development and Flood Risk England

• Development and Flood Risk – guidance for the construction industry. CIRIA 2004.

• Preparing for Floods. DTLR 2002

• Flood resilient Homes. Association of British Insurers 2004

• Flood Products: Using flood protection products: a guide for homeowners. CIRIA and Environment Agency

• Damage Limitation: How to make your home flood resistant. CIRIA and Environment Agency

• After A Flood: How to restore your home. CIRIA and Environment Agency

• Flooding in gardens: How to cope with excess water in the garden. Environment Agency & Gardening Which? August 2004

Technical guidance on SUDS • SUDS Design manual for England & Wales (CIRIA C522)

• SUDS Best practice manual (CIRIA C523)

• SUDS Hydraulic, structural and water quality advice (CIRIA C609)

• The Environment Agency website

http://www.environment-agency.gov.uk/business/444304/502508/ 464710/464767/?lang=_e

SUDS adoption • Interim Code of Practice for Sustainable Drainage systems. National SUDS Working

Group July 2004

• Framework for Sustainable Drainage Systems in England & Wales. National SUDS Working Group May 2003

• Model agreements for sustainable water management systems: Model agreements for SUDS (CIRIA C625)

• Making space for water: Developing a new Government strategy for flood and coastal erosion risk management in England: A consultation exercise. July 2004.