24Apr 2014

Evaluation and Accreditation – what differentiates a good SuDS scheme from a poor one?

Anthony McCloy, McCloy Consulting


Other than considering a scheme against available guidance, or the application of personal judgement, which in most cases is extremely subjective; how would you go about assessing whether a SuDS scheme was an exemplar or something that should be used as an example of how not to do it?


It is evident that determining the ‘quality’ of a scheme against the national standards alone will not provide a sufficiently rigid set of evaluation guidelines; as they consider the volume of water primarily, with a conscious nod of the head towards water quality. Consequently, this may not stop piped systems with large deep ponds or basins (akin to craters) located prior to the point of discharge being considered acceptable.


On the flipside most sites are unique and each have their own set of design parameters and constraints within which to deliver the final scheme, therefore the criteria for evaluation has to be flexible enough to take extenuating or special circumstances into account.
There is also a wide raft of variables by which a scheme could be assessed upon, from how it meets the requirements for climate change adaptation to how the look of the SuDS system marries in with local heritage typologies, all of which go well beyond the remit of the Standards and will more likely be considered by the planner.


Personally, I have never been a big fan of the ‘point scoring’ take on accreditation, as I have found that many designers default to a paint by numbers design process, or more cynically  try to identify loopholes in the process, rather than considering the scheme holistically.


Therefore, a balanced evaluation has to incorporate a mix of tick boxes (meeting quantity and quality minimum requirements for example), in addition to appraisal of the aesthetics of the scheme. The more subjective aspects could include a consideration of how much had been made of the opportunities provided by the site, in terms of how the drainage has influenced the site layout and how the drainage has maximised the use of the landscaped and trafficked areas around the site.


Similar considerations have been taken for appraisal of Green Infrastructure and Ecosystem Services, however, we need to determine and be very careful whether every aspect of the design should be monetised.


Many designs do not end up being used as envisaged. A prime example of this is the extended detention basin in Lamb Drove which is situated beside the raised play space. From talking to local residents the children prefer the more natural basin as a play area and the more sterile raised play area gets neglected. Perhaps children would make for a good SuDS assessor?


Figures 1 & 2: Detention basin and raised play area at Lamb Drove


It would seem that SuDS evaluation or accreditation will not be a straight forward process and there are likely to be many differences of opinion along the way. With than in mind I will leave you with a quote which I think sums up the situation with a degree of elegance;


“Just because we cannot see clearly the end of the road, that is no reason for not setting out on the essential journey.” Robert F. Kennedy – The New York Times (July 2, 1964)


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