Ensuring that most new developments have sustainable urban drainage systems could cost £160M in capital and maintenance costs, and require 150 new local authority staff.

The Department for Environment, Food and Rural Affairs last week launched a draft surface water drainage strategy for consultation, which sets out measures to reduce the £270M annual cost of intra-urban flooding (Surveyor, 14 February).

There would be a net benefit of resolving the legal uncertainty over which organisations are responsible for the adoption of SUDS of up to £1.2bn, according to DEFRA. But its assessment also reveals that reducing the risk of surface water flooding by including measures such as porous paving, soakaways, swales, and ponds would require £160M in additional investment up to 2050, with maintenance a large proportion of this.

The calculation was based on CIRIA’s estimate that maintaining SUDS costs more than 100 times per hectare than traditional piped drainage systems, although DEFRA said a more robust cost was needed.

Tony Poole, principal drainage engineer at Bradford City Council, told Surveyor last week that it was ‘hard to see’ how the ideas in the strategy would be implemented, unless additional resources were provided (Surveyor, 14 February).

DEFRA proposes that the cost of councils or sewerage firms undertaking the work should be passed on to residents – if possible, to those benefiting from reduced flood risk. But the issue of designing geographically-variable charging would ‘need to be resolved,’ said DEFRA.

It previously acknowledged that the idea of requiring residents in the flood plain to pay a special levy was ‘almost universally condemned’. The department pledged that, were any additional costs incurred by local authorities – also to include £15M to produce new surface water management plans – ‘we will ensure that these are fully funded’.

Surveyor’s Flooding – strategies for assessing urban risk event takes place in London on 15 April. www.surveyorevents.com