SUDS, floods and Tewkesbury

Tewkesbury during last year's flooding

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Sustainable drainage systems (SUDS) need to be the focus for a shift in flood risk management thinking on, engineers were told last week.

Speaking at the SUDS 'n' Floods conference in Tewkesbury Gloucester, a year a after the devestating floods, Arup associate David Schofield illustrated the need for joined up thinking on the SUDS issue with findings from a visit to a flagship scheme in Portland Oregon on the US west coast as part of a 2006 mission by British Water's sustainable drainage focus group for the DTI.

Schofield also provided the best working definition of what SUDS is: "Sustainable drainage is drainage that meets the needs of the present without compromising the ability of future generations to meet their own needs."

CIRIA associate Paul Schaffer emphasised the need for local government to take leadership in flood risk management, following the government's flood risk proposals, announced last month.

Schaffer called for a more a holistic approach to the issues flood risk management. The workings of the regulatory regime that deal with surface water quality such as the Water Framework Directive and PPS25 need to be taken on board by local government, clients, consultants and contractors alike, he said.

CIRIA has established Landform (Local authority network on drainage and flood risk management) as a forum for shared experiences, good practice and information on policy.

Severn Trent sewerage asset manager Phil Gelder outlined the strategy employed by his company during last year's flood events in Gloucestershire and put forward a three strand strategy for future events:

First, the mitigation of risk by defending assets to a higher standard, second, reduction of risk by reinforcing the network and duplication of pipelines (resilience), and finally by managing unforeseen emergencies by rigorous contingency planning.

Sustainable drainage advisor to Dwr Cymru Welsh Water (DCWW) Jeremy Jones summed up the issues: "It's about reducing flooding, mitigating climate change, reducing pollution and contamination, saving energy.....while supporting conservation and recreation."

DCWW's flow reduction strategy takes a long-term view of the problem of surface water drainage and sees the the problem being addressed over a period of perhaps thirty years as opposed to the relatively short time frames envisaged by an AMP timeframe.

The pilot integrated urban drainage (IUD) schemes commenced in DCWW are similar to the 15 in England launched by DEFRA. These schemes said Jones, are part of the wider solution incorporating ideas such as "sexy traffic calming" which creates chicanes made from planters which absorb 80% of water runoff.

In the afternoon, Hydro International director Alex Stephenson warned – as had many other speakers from the podium and the floor, that SUDS was not a panacea to all storm-water problems.