Practitioners involved in the design and delivery of sustainable drainage systems (SUDS) in Scotland believe they have achieved success aided by powerful legislative drivers.  However, many believe reluctance to adopt and maintain SUDS features is hindering further progress, a new survey suggests.

SUDS in Scotland – Experience and Opportunity was conducted for the Engineering Nature’s Way knowledge-sharing website by sustainable drainage specialist Hydro International in association with CIWEM and British Water.  It set out to gauge how successful professionals believe Scotland has been in delivering SUDS and what further barriers there might be to progress.  It also aimed to identify lessons learned as England and Wales prepare to implement new national standards for SUDS expected in 2014.

The 151 practitioners who participated in the survey represented a broad range of professional disciplines involved in the specification, design, delivery and approval of SUDS in Scotland, providing a snapshot view of current progress.  Amongst those represented were consulting engineers, developers, environment agency and water company professionals.

The overwhelming majority (96.8%) believe Scotland has successfully implemented SUDS since the implementation of the Water Environment and Water Services (Scotland) Act (WEWS) in 2003.  However, very few (2.4%) believed it has been completely successful.  84.7% agreed legislative drivers have helped Scotland to make more effective progress with SUDS than England and Wales.

Many respondents expressed frustration that authorities had been very slow to adopt SUDS systems, regarding this as a significant barrier to progress.   Most believed regulation and guidance to be insufficiently clear for both maintenance (59.8%) and adoption (67.1%) and most (77.8%) felt there was inadequate funding for the adoption and maintenance of SUDS in Scotland.

Only about half (52%) of respondents were satisfied that current regulation and guidance gives practitioners freedom to specify from a full toolbox of both “natural” and manufactured /proprietary SUDS features.

Most believe that proprietary SUDS features either require the same maintenance or are easier to maintain than natural SUDS features with less than a third (30.8%) believing they are more difficult to maintain.

Surface Water Quality
Scottish legislation has focused strongly on stormwater quality and the majority agreed that the requirements for design and implementation of surface water treatment are clearly defined by regulation and guidance in terms of an ‘effective treatment train’ (77.2%) and what constitutes a ‘level of treatment’ (67.8%).

However, the majority (65%) of those with relevant experience believed that the policy of the Scottish Environment Protection Agency (SEPA) to classify proprietary systems as a level of treatment only in “exceptional circumstances” was a barrier to the design of effective SUDS solutions.

Respondents agreed that further developments of the SUDS for Roads Whole Life Cost and Whole Life Carbon Toolkit from SCOTS would be welcome, together with the development of other industry tools to assist with the design and costing of both proprietary and natural SUDS.

Alex Stephenson, Director of Hydro International’s UK Stormwater Division and Chair of British Water Sustainable Water Management (SuWM) Focus Group said:  “Whilst Scotland has led the way in implementing SUDS, there are some important lessons to be learned.  In particular, there are considerable frustrations in the number of SUDS features being adopted and maintained effectively in Scotland and this had implications on both sides of the border.

“In particular, the need for robust costing and predictability in the maintenance requirements of SUDS needs to be addressed.  This, in turn, can provide confidence for the adopting bodies.  I believe Scotland also needs to think again about the restrictions placed on specifying manufactured SUDS features, which was reflected in considerable frustration amongst respondents.”