The ultimate stakeholder of any drainage system is the public. Effective drainage of wastewater and adequate protection against flooding are prerequisites for all properties.
In the UK responsibility for drainage is divided between a number of organisations and has recently been clarified with the Flood and Water Management Act (Defra, 2010) in England and Wales and the Flood Risk Management (Scotland) Act (Scottish Government, 2009). Sewerage undertakers are responsible for the public sewerage system that serves most urban areas and some rural areas.
Local authorities may be unitary or, for example, district or borough councils as part of a two-tier system. Within England and Wales it’s proposed through the Flood and Water Management Act (Schedule 3) that upper tier local authorities (county and unitary authorities) will review all SuDS schemes and adopt those serving more than two properties. For ordinary water courses in England and Wales this lies with the local drainage board or local authority. The responsibility for the maintenance of minor watercourses in rural and urban areas falls to riparian owners and the local drainage authority. For statutory main rivers the function lies with the Environment Agency. Similar mechanisms exist in Scotland and Northern Ireland. Highway drainage is normally the responsibility of the local highway authority. Under a non-statutory agreement, highway drains may discharge into public sewers and vice versa. Within England and Wales and Scotland the environmental regulators, the Environment Agency (EA) and Scottish Environmental Protection Agency (SEPA) respectively have a strategic role in managing flood risk. However, the responsibility for drainage is fragmented which makes management more complex.
Property owners are responsible for drainage within the curtilage of their property. They are also responsible for insuring their property against flooding.
Local flood risk management and managing surface water flooding requires the co-operation of the relevant stakeholders, these being the sewerage undertakers, highway authorities, local authorities, environmental regulators, property owners and insurers. For new developments the role of the developer and the planning authority will also be important. Further information can be found in CLG’s National Planning Policy Framework and its associated technical guidance.
Who should get involved
The development of more sustainable approaches to manage exceedance flooding will only be fully realised through good stakeholder interaction. At the start of any project, relevant stakeholders should identify who is responsible for the flooding (which maybe a number of parties) and establish who also has an interest in its resolution. The problem should be clearly defined and communicated to all parties with partnerships and effective engagement playing a fundamental role in managing future flood risks.
Designing for exceedance is not just for drainage engineers. It involves designing and managing the urban environment, whether as part of a new development or as part of a retrofit scheme. It needs many disciplines and people (including communities, highway engineers, spatial planners, architects, landscape architects and urban designers) to work together to help manage exceedance in the best way, balancing and mitigating the different risks that arise.
In any new development, it is important that planners and planning committees making decisions to ensure that the developers have designed for exceedance. So, if flooding occurs, it needs to be managed safely to reduce the risk of water entering homes or businesses.
If practitioners design for exceedance, it is very unlikely that new development will suffer flooding from an urban drainage system other than for the most extreme rainfall or cause additional flooding (note that even a careful approach to managing rainfall cannot prevent some flooding occurring from extreme events). Architects and urban designers need to advise developers about the importance of designing for exceedance, with it forming a key and early part of the planning process.
Importance of engagement and collaboration
Engagement and collaboration is essential not only externally with the public, communities and key stakeholders, but internally within the design team, and project partners. People’s perceptions and traditional ways of working can be a barrier to designing for exceedance.
Engagement within and between local authority departments helps to overcome barriers (such as using highways to convey exceedance flow at the request of flood engineers) and was clearly identified in this project’s online survey as the primary need when designing for exceedance. A good example is ensuring councillor and departmental (director) support for using the highways as a secondary function of conveying surface flows by providing leadership to those making day to day decisions. This can break down perceived or real barriers and help to evaluate risks appropriately with different disciplines working together. It often takes time to build up trusting relationships and is increasingly important across all service functions, not only for exceedance.
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