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“Floods and SUDS”

Sustainable Drainage Systems (SUDS): planning and insurance issues

Photographs to be inserted in final version:

SUDS detention basin next to a large supermarket. (Note the shopping trolleys and blocked drain.)

SUDS detention basins constructed in 2003 for a new road junction. Note how they have filled up after a shower of rain. These basins drain away into a narrow watercourse which runs close to housing. No changes were made to the watercourse to cope with additional flows from the road junction.

SUDS detention basin in the headwaters of a culverted watercourse. When first constructed, soil from the newly excavated basin blocked the culvert leading to backup and overflow of the detention basin resulting in localised flooding.

photos ©copyright 2005. David Crichton

Flooding in the centre of Dundee in 2004 due to backup from combined sewers. Photo, Dr Andrew Black, University of Dundee

By David Crichton

Fellow of the Chartered Insurance Institute

Chartered Insurance Practitioner

Visiting Professor, MiddlesexUniversity Flood Hazard Research Centre

Visiting Professor, Benfield Hazard Research Centre, UniversityCollegeLondon

Honorary Research Fellow, University of Dundee

Preface

Under Scottish Planning Policy (SPP7), every local authority must establish or participate in Flood Liaison and Advice Groups (FLAGs) which include an insurance representative.

The author has been funded by the insurance industry since 1996 to attend regular meetings of FLAGs (formerly called “flood appraisal groups”) all over Scotland to advise them on insurance issues. He is a member of all 19 such groups involving 28 local authorities, covering 98% of the Scottish population. He has attended more such meetings than anyone else, and has been able to help to spread information and best practice. This guidance note is intendedto answer some of the most frequently asked questions on SUDS and drainage issues that have arisen during Flood Liaison and Advice Group meetings over the last ten years.

Recent publications by David Crichton include:

Crichton, D., (2005) “Flood risk and insurance in England and Wales: are there lessons to be learnt from Scotland?” Technical Paper Number 1, Benfield Hazard Research Centre, UniversityCollegeLondon. Available for free downloading from

Crichton, D., 2005. “Flood Risks and Insurance Fact File” Chartered Insurance Institute, fourth edition, London, June 2005. Available for downloading (for CII members and subscribers only) from

Crichton, D., 2005.“Insurance and Climate Change”. Proceedings of a Conference on

Climate Change, Extreme Events, and Coastal Cities: HoustonLondon. Houston, Texas, 9th February 2005.

The paper is available from:

Meyer, A., and Crichton, D. January 2005. “Contraction and Convergence”. Post Magazine Weather supplement, 29th January 2005. London.

Crichton, D. January 2005. “The role of private insurance companies in managing flood risks in the UK and Europe.” In Urban Flood Management, eds. A. Szöllösi-Nagy (UNESCO) and C. Zevenbergen. ISBN 04 1535 998 8, 2004, 160 pp. A.A. Balkema Publishers, Leiden, Netherlands. Available from or .

Roaf, S. Crichton, D., and Nicol, F. , 2005. “Adapting Buildings and Cities for Climate Change” 361pp. Architectural Press and Elsevier Press, London. ISBN 0 75065 9114

Contents

Introduction

Frequently Asked Questions

Q1. When should one ask for SUDS? Should SUDS be considered for very small developments, for example, gap sites?

Q2. Why would a site not be suitable for SUDS?

Q3. How should detention basins be used?

Q4. Can SUDS be used outside urban areas?

Q5. Can SUDS be used on brownfield sites?

Q6. What powers do SEPA or EA have regarding SUDS?

Q7. What if the development does not have enough land for SUDS?

Q8. Should SUDS apply to a flood management scheme as well?

Q9. Who is responsible for maintenance of a SUDS scheme?

Q10. One aspect of SUDS is that swales and detention basins may be needed to hold the water until it can drain through a controlled outlet with infiltration or dry out naturally. Elected council members have expressed reservations about such features and also about retention ponds on the grounds of the possible risk of children falling in and drowning. Is there a serious safety issue?

Q11. Should SUDS be to a 1 in 50, 1 in 100, or 1 in 200 design standard?

Q12. If SEPA approve a SUDS scheme, does that mean they consider the scheme will have a neutral impact on run off?

Q13. Can SUDS lead to pollution?

Q14. What is the position regarding culverts?

Q15. How do Building Regulations and Building Control fit in with SUDS?

Q16. If the water authority/company take on responsibility for a SUDS scheme, will they provide the engineering expertise?

Q17. It takes a long time for the water authority/company to approve a SUDS scheme. If the designer is a qualified engineer, is it not possible for the engineer to certify it as meeting the requirements?

Q18. Can rainwater be recycled?

Q19. What issues arise with phased developments?

Q20. In places like Singapore, Los Angeles, and Madeira, they have large storm drainage channels to take surface water away. Could this not be tried in the UK?

Q21. One developer has been told by SEPA that they don’t need SUDS because only roofwater is involved so there are no water quality issues.

Q22. Who can enforce remedies for a breach of a SUDS design?

Q23. Some householders are complaining that their gardens are always waterlogged and they want them to be drained.

Q24. What about roads issues?

Q 25. If someone’s property is damaged by flood or drainage surcharge, can they sue the local authority or the water company?

Q26 What are insurers’ concerns about SUDS?

Q 27Some insurers are now refusing to cover houses within 50 metres of a river or pond. Will this be a problem?

Q 28What are the implications of Marcic v Thames Water for insurers?

Q 29Will SUDS make it harder to obtain a mortgage?

Q 30 The public has perceptions of how a pond should look based on experience of ponds in parks and the grounds of stately homes. Will the public demand aggressive management of ponds (dredging, weed removal etc) rather than leaving them to stabilise naturally?

Q31 Can soakaways be positioned near to the boundary of the curtilage?

Q32 How much will Scottish Water charge for maintenance?

Q33 What are CSOs?

Q34 What is source control?

Q35 Is groundwater a problem?

Q36 Is planning permission needed to build a pond?

Q37 Are there any guidelines for planting SUDS areas?

The following questions (38 – 44) arising in FLAGS relate specifically to Scottish Water issues and the answers have been supplied directly by Scottish Water

Q 38 Will Scottish Water try to discourage SUDS schemes that have a high maintenance cost in the future?

Q 39 Scottish Water is less concerned about habitat than SEPA. Will they seek hard engineering solutions rather than soft solutions? For example they will now accept hydro cells in some areas. Are we going to end up with plastic boxes everywhere?

Q 40 When “SUDS for Scotland” is agreed, will SW take on the responsibilities for monitoring surface water quality currently held by SEPA? Will SW have responsibilities for preventing diffuse pollution under the WFD/WEWS?

Q 41 There seems to be conflict already within SEPA between those responsible for WFD, and those concerned about flood protection, despite the fact that WEWS emphasises the over riding importance of liaison between all the agencies concerned to ensure sustainable flood management. (It must be emphasised that in Scotland, WFD has not been transposed without modification as it has in other countries). What is SW policy on this? WFD or sustainable flood management?

Q 42 Will SW take into account the issue of insurability in their new construction standards and vesting conditions? Have they consulted the insurance industry about insurers’ concerns? Will this also apply to design standards? For example a common problem is waterlogged gardens because of inadequate drainage. Also as new developments mature, residents are likely to build conservatories, extensions, paved patios and driveways etc, which will increase run off. This is often not allowed for in the original design.

Q 43 What allowance is made for climate change by Scottish Water?

Q 44 Will SW say that the capital and maintenance costs of SUDS are too high to be justified for a particular site? Can Councils argue when they need affordable housing for low-income families? As SW has no legal obligation to accept surface water drainage into their systems, presumably this would prevent the development from proceeding?

Miscellaneous questions for debate

Appendix 1 Extract from the CIRIA Maintenance Framework Agreement for Scotland

Appendix 2: Extract from the residential property section of the ‘insurance template’

Appendix 3: Greywater

Appendix 4: Design of Drains and Sewers

Appendix 5: Marcic v Thames Water Utilities

Appendix 6: Model letter to developer

(Courtesy of Aberdeenshire Council)

Appendix 7: Results of a survey of insurers.

References.

DISLAIMER

It should be noted that the following is written mainly from an insurance perspective, in the light of the expiry of the flood insurance guarantee, which will make it increasingly more difficult and expensive to obtain household insurance in flood hazard areas. It is mainly intended to assist insurance company underwriters and local authority planners, concerned about drainage and flooding issues.

It is not professional advice and should not be relied on as such. Nor does it necessarily represent the views of the Benfield Hazard Research Centre, Middlesex University Flood Hazard Research Centre or the University of Dundee.

The author would be grateful for comments and suggestions.

Acknowledgements

The author is very grateful to the Scottish Environment Protection Agency (SEPA), Scottish Water (SW), the Scottish Executive, and the Environment Agency (EA) for their helpful comments and suggestions regarding the content of this note. This should not be taken to imply that the note necessarily reflects their official policy, (in some cases it specifically does not) and if in doubt, reference should be made to the relevant agency.

The author also wishes to thank Dr Chris Jefferies of AbertayUniversityand Kate Zabatis of United Utilities for their valuable commentsand contributions.

Finally the author is grateful to all the insurance companies and Flood Liaison and Advice Groups around Scotland who have raised all the questions dealt with in the paper, and hopes that the answers will be of assistance to the planning community not just in Scotland but in the rest of Britain.

Short Glossary

CARControlled Activities Regulations

COPA 74Control of Pollution Act 1974

CSOCombined Sewer Overflow (see Q33)

DIADrainage Impact Assessments

EAEnvironment Agency

GreywaterSee appendix 3 and Q33.

SEPAScottish Environment Protection Agency

OfwatOffice of Water Services

PPG 25Planning Policy Guidance 25 (English planning guidelines)

SPP7Scottish Planning Policy number 7 (flood) – replaces NPPG 7

SUDSSustainable Drainage System(s)

WEWSWater Environment and Water Services (Scotland) Act 2003

WFDWater Framework Directive

(There have been a number of variations in the description of SUDS. Originally it stood for “Sustainable Urban Drainage Systems”, but it is now viewed as not being restricted to urban and is called simply “Sustainable Drainage Systems”. The acronym is therefore sometimes shown as “SuDS” but is generally still shown as “SUDS”).

Background

“SUDS” refers to “Sustainable Drainage Systems”, and the use of SUDS is growing in response to the rapid pace of building development and the desire to avoid overloading existing drainage systems, many of which are over 100 years old. Surface water can be disposed of in two ways:

  • to groundwater using soakaways or ponds, or
  • to existing watercourses, standing water (lakes/lochs) or the sea

Almost every new housing development in Britain will in future be likely to have some form of SUDS (Northern Ireland is currently drawing up guidelines). Some years ago, with the permission of the Association of British Insurers, the author represented insurance interests on the steering groups which produced the SUDS manuals used by property developers and local authorities[1]. While he supports SUDS in principle, after having subsequently advised more than 30 local authorities on the subject, he is concerned about some of the problems arising in practice. Research by the author into insurance company attitudes to SUDS shows that as at June 2005, hardly any of the major insurers had heard of SUDS or understand how they work.

It seems clear that the insurance industry is not being consulted about SUDS and is largely unaware of how SUDS will affect future risks. It is hoped that this paper will help to raise awareness of the issues.

Application

Although the questions shown in this paper come mainly from Scottish Planners, the notes are intended to be for the benefit of planning and development control staff throughout Britain, to help them to deal with drainage and climate change issues effectively. It is also intended to be of assistance to insurance underwriters, to help them to understand more about the latest developments in drainage systems.

There are a number of differences between Scotland and the rest of Britain,

Geographic and climatic differences:

  1. Scotland has 40% of the land area of Britain but only 9% of the population. However most of the population is concentrated in urban areas where densities are comparable to England at around 30 dwellings per hectare.
  2. During the industrial revolution, many towns in Scotlandgrew up around rivers which were used to provide power for engineering and to treat textiles such as linen and jute.
  3. There is a higher risk of snowmelt floods in some areas of Scotland, although this is reducing due to climate change.
  4. Coastal flood risk tends to be lower because shoreline geology is more “rocky” and suffers less from erosion. Thus while there are now shoreline management plans (SMPs) for the whole coast of England and Wales to consider issues such as defence versus managed realignment, in Scotland, it is only necessary to have SMPs in certain areas where the shoreline is “soft”.
  5. In Scotland, sea level rise will have less of an effect because ground levels in the North and West are rising at around the same rate due to tectonic rebound.
  6. Climate change will have a significantly greater effect in England and Wales than in Scotland in terms of rainfall, droughts and rising temperature.

Legislative and economicdifferences:

  1. Privatised Water Companies operate in England and Wales, whereas there is a single Water Authority (Scottish Water) in Scotland. (In March 2006, Westminster announced its intention to privatise Scottish Water, selling it for £2 billion. However the Scottish Parliament responded quickly to state that Scottish Water was owned by them and not Westminster and they had no intention of privatising it.)
  2. Since 1995 planning policy has been much tougher in Scotland than in England, and the current planning policy (SPP 7) effectively prevents any building where the flood hazard exceeds the 200 year return period for housing, or 1,000 years for vulnerable developments such as hospitals etc, in line with the Insurance Template. By contrast, in England there is a planning “guideline” (PPG 25), to be replaced soon by a “policy statement” (PPS 25), both of which allow building in the floodplain if there is nowhere else suitable (the sequential approach). Thus in England, large scale housing development is planned for the Thames Gateway area, and PPS 25 says ““It is estimated in the Thames Gateway where more than 90% of the land for development lies in designated flood risk areas, a sequential approach that allocates housing to the lowest risk areas could reduce potential flood risk losses by up to 52%.” (Section 6 [35] )
  3. The Scottish Framework agreement for SUDS (outlined in Q9 and Appendix 1) has no equivalent in England and Wales, where there are as yet no standard agreements on construction, adoption or maintenance of SUDS[2]. There is however an interim Code of Practice on SUDS in England and Wales[3] which goes some way to provide agreement methodologies. Background paper 8 for the Making Space for Water consultation exercise[4], suggests that uncertainty over ownership and responsibility issues constitute a disincentive to their greater use.
  4. Under the Water Environment and Water Services (Scotland) Act[5], which implements the Water Framework Directive in Scotland, Scottish Water will be obliged to adopt a limited set of above and below ground SUDS in certain circumstances. This is likely to start some time in 2006.
  5. Certain aspects of SUDS such as soakaways will require regular maintenance by the property owner. In Scotland the Building (Scotland) Act[6] contains a section on “continuing requirements” which allow the local authority to specify maintenance requirements in the building warrant (this has not yet been introduced by the Scottish Building Standards Agency). There is no similar power in England and Wales. Meantime in Scotland some local authorities provide house buyers with an “entry pack” which sets out the continuing maintenance needs.
  6. Following the Strategic Environmental Assessment EU Directive and the subsequent Environmental Assessment (Scotland) Act 2005, it is now law in Scotlandthat the person commissioning a plan or programme which is likely to have environmental impacts must produce an Environmental Assessment. In Scotland this has been extended to include a “Strategic Flood Risk Assessment”. There is no similar requirement in England and Wales (although it was proposed in December 2005 in PPS 25). In Scotland, insurers can sue a local authority if they fail in their obligation to undertake a Strategic Flood Risk Assessment.
  7. Scottish Water will not sanction any new developments where surface water drains into watercourses unless the relevant local authority accepts responsibility for the additional discharge, and presumably any flooding and legal liability which might result.
  8. Scotland has Flood Liaison and Advice Groups (FLAGs) where drainage and flooding issues can be regularly discussed and best practice disseminated. These FLAGS cover 98% of the population in Scotland and are attended by all relevant stakeholders. There is no equivalent in England and Wales, although ODPM has recommended that local councils consider following the Scottish example[7].
  9. Scotland is subject to the Flood Prevention and Land Drainage (Scotland) Act 1997, which imposes certain statutory duties for assessing and reporting flood hazards and the maintenance and cleaning of watercourses and gullies. There is no corresponding legislation in England.
  10. Scotland is also subject to the Roads (Scotland) Act 1984. Councils can issue an Order[8] to the landowner or occupier requiring measures to be taken to prevent surface run off from flooding an adjoining road. There is no corresponding legislation in England.
  11. The EA regards SUDS as having a number of applications, including “flood management”, whereas SEPA regards it primarily as a means of controlling diffuse pollution.
  12. Building on floodplains has virtually ceased in Scotland, but continues on a major scalein England, where 56% of local authorities ignore EA advice[9] about flood risks. In 2004, there were nearly 700 new houses built in flood hazard areas in England against the advice of the EA[10].
  13. A major increase in the programme of flood defence work in Scotland, combined with tight planning controls is likely to result in a reducing number of unprotected flood plain developments. In England and Wales, spending on flood defence work is inadequate according to the government’s own reports, and the number of flood plain developments is still growing. In Scotland no application for grant aid for flood defences has ever been turned down due to budgetary constraints, the budget has simply been increased. To encourage flood defence projects, grant aid has been increased to 80% and there is a national target of defending all existing properties against the 100 year flood by 2008, taking climate change into account.
  14. England, Wales and Northern Ireland have transposed the EU Water Framework Directive (WFD) as it stands, whilst Scotland has transposed it in a more holistic way, giving sustainable management of flood risks priority. The legislation has to enable Scottish Local Authorities to fulfil their statutory duties for watercourse maintenance under the 1997 Flood Prevention Act, as failure to do so would lead to legal liability should floods occur. Sustainable flood management is essential as climate change impacts result in increases in rainfall. Often the most sustainable solution is to increase the storage capacity of rivers and lakes upstream, rather than building flood walls through towns and cities as is proposed for Carlisle.
  15. In Scotland, flood management is under the control of the local authority, this means that only the local authority has the power to initiate flood defence schemes, not SEPA. The local authority is therefore democratically accountable if they fail to defend properties adequately: they cannot “pass the buck” to SEPA in the way that English local authorities do with the EA. This is a strong incentive for elected members to refuse to allow building in flood hazard areas, especially as, unlike England, there are no targets for numbers of new houses in each council area.
  16. In Scotland, the sewer undertaker is only obliged to accept sewage if there is sufficient capacity in its system, whereas in England and Wales, the householder has a right to be connected to public sewers under section 106 of the Water Industry Act 1991, even if the sewer has insufficient capacity. This means that in England and Wales sewers are much more likely to be overloaded leading to overflows and sewage flooding, while in Scotland new building is effectively prevented in areas where the sewage network has reached full capacity, until there is investment in new sewage infrastructure. Developers are reluctant to pay for additional sewage capacity beyond their immediate needs because this surplus cannot be “banked” for future developments, but it also means that if another developer comes along they can obtain the benefit of this surplus capacity.
  17. The Scottish Executive has powers to insist on resilient reinstatement after a flood or storm. There are no such powers in England.
  18. For dams and reservoirs subject to the Reservoirs Act, the enforcing authority in England and Wales is the Environment Agency while in Scotland it is the local authority. In other words the enforcement authority is directly democratically accountable in Scotland, but only indirectly in England and Wales (although the Scottish Executive is considering making changes to this).
  19. The Scottish Executive has devoted substantial funding to encourage insurance schemes to provide household contents insurance on a pay with rent basis for low income tenants of local authority and housing association homes. Most Scottish local authorities now administer such schemes. There has been no such funding in England and Wales. In Scotland, 43% of families in social housing are uninsured. In England the figure is 61%.

Introduction