Opportunistic retrofitting

When changes are made to the urban environment there is an opportunity to do a wide range of things differently. This may be when repairing, refurbishing or replacing part of an existing area or surface, or even reconstructing the grass and paved areas on a single plot.

There may be no immediate need to address surface water flooding or pollution, but simply an opportunity to modify a small part of the drainage system to manage water better. Green Roof Retrofit

Here it is particularly important for responsible bodies, eg highway authorities, to understand and recognise opportunities that relate to their programme of works. In a time of economic constraint, getting more for less is an obligation that needs to be recognised by all the major players in urban development.

Where the introduction of SuDS helps another responsible body to meet their objectives, it may be that the cost of a scheme can be shared. This approach will most likely achieve other objectives, for example when retrofitting GI (eg by planting extra trees and greening streets) the opportunity to modify drainage systems to connect to the green areas, to keep them watered and also to absorb some of the runoff should not be overlooked.

Such an approach can also improve the biodiversity of an area and support the aims of biodiversity action plans.

Through a wide range and number of small measures, opportunistic retrofitting can significantly reduce the overall runoff from a much wider area. This has been recognised in several cities in North America, including Toronto, Portland, Seattle and New York.