Designs on the future

FIRST THERE was Boscastle, then there was Hull, Sheffield, Gloucester and Tewksbury, and these have now been superseded in our minds by Cockermouth, Workington and other parts of Cumbria. Events such as these can be very localised as with Boscastle, or more widespread as with Gloucester and Tewksbury.

Often only certain areas grab the headlines because of the severity and possibly “interesting” pictorial opportunities or specific local issues for the Press. However they are often part of much more widespread events with a significant impact on the many people caught up in them to varying degrees and they do seem to be occurring with a greater frequency and severity.

The floods of 2007 were extensive and part of a widespread series of events covering many parts of the UK. The subsequent reports into the incidents have received much publicity. They highlighted a range of issues and, although some were logistical, they have included a long list of proposed changes to the design and maintenance aspects of flood protection schemes and the management of surface water.

Government considered the reports and responded positively to many of the recommendations and subsequently consulted on the draft Floods and Water Bill. The recently published Floods and Water Management Bill is a reduced version of the draft Bill because of the shortened time available in the parliamentary year.

Flood plains

Some commentators have asserted that the flooding incidents were predictable, a consequence of relying on outdated planning systems and protection methodologies and not investing the necessary resources because of more publicly attractive calls on limited financial resource.

There has also been the problem of continued expansion of existing urban and industrial developments as well as new developments in the flood plains of our rivers and other low lying areas with predictable risks of flooding – especially if maintenance was compromised. There are also the consequences of current attitudes to developments, to transport and land use and to the aesthetic appearance and convenience of developments that have affected surface water movement from source to sea.

Some will ask, why can’t we apparently cope with monsoon-like events when other countries do on a regular basis and this is where an understanding of the concepts of risk and return period become so necessary. Where such events recur regularly either flooding is accepted as a way of life or the developments have been designed to accommodate the large amounts of surface water, including simple things like deep curbs to streets and direct unimpeded runoff into water courses. There is often though less emphasis on investment in systems and processes to protect the environment from the consequences of excessive runoff whether it be by erosion or contamination from suspended solids or chemical pollutants in the surface water.

The reports into UK flooding incidents made many extensive recommendations into how we should respond to the consequences of intense rainfall events with improved design and construction of surfaced water management systems and their management and maintenance.

National strategy

The recently published Floods and Water Management Bill is the Government’s response to implement measures to mitigate the most significant of these recommendations. It is to be hoped that the envisaged timescale that is available to the current Parliament is maintained so that the provisions do reach the statute books.

The Bill assigns responsibility for a national strategy to the Environment Agency and for strategies and management responsibilities at the local level to relevant local authorities. These responsibilities require that drainage plans for all new developments need to be approved and approval will be required before any construction can start.

It provides funding to local authorities go along with these added responsibilities, which crucially includes a responsibility for maintenance of sustainable drainage systems (SUDS).

The approval process will require that drainage systems take account of the National Standards for the design, construction, operation and maintenance of SUDS that are to be drafted by the spring of 2010. There is also to be an end to the automatic right to connect surface drains to sewers to encourage alternative approaches to controlling surface water at source rather than to direct it away as quickly as possible as has been the habit in the past.

These aspects of the Bill should promote a coordinated use of the wide range or toolbox of technologies, proprietary and natural, either alone or in combination, as is most suitable for the nature and siting of the development.

The National Standards are being developed under the auspices of CIRIA by a group that includes representatives from all groups covering the wide range of expertise relevant to successful application of SUDS. By coincidence the information from the British Water SUDS Group on proprietary systems is also nearing its completion.

The revised Technical Guidance to proprietary sustainable drainage systems and components – SUDS will be published at a conference next month.

The conference, Surface Water – The Sustainability Challenge, will be held on February 9 at the Arup Campus in Solihull – full details are available via the British Water website.

A keynote address from Defra will review the status of the Floods and Water Management Bill, subsequent papers will cover different aspects of SUDS designs and applications to be followed by an overview of the revised British Water Technical Guidance for SUDS.

The concluding paper by Prof Ashley (Sheffield University and UNESCO IHE) will address the all important issue of retrofitting systems and also include a personal viewpoint on particularly pertinent aspects from the day’s proceedings.

Weather events

The intense rainfall events of recent years have highlighted the problems of surface water management and stimulated much activity by everyone who could have an interest in mitigating of the consequences of potentially more frequent weather events.

Government is providing the regulatory and management background to facilitate the application of the wide range of solutions that are available. It will be very important that the National Standards are comprehensive and include the full toolbox of proprietary and natural technologies. This will promote the application of the most appropriate and sustainable designs that with subsequent management and maintenance will ensure that they provide the necessary protection and operate to their full potential well into the future.

Dr Ian Pallett is technical consultant at British Water. T: 020 7957 4554