PROSuDs: Providing Real-world Opportunities for Sustainable Drainage Systems

Lead Research Organisation: University of Portsmouth
Department Name: School of Civl Engineering and Surveying

Abstract

Developments, such as housing estates, generally mean that more rain "runs off" the surface compared to green fields. This increased "urban runoff" often causes more river or surface water flooding downstream and also contains pollutants washed off from surfaces, such as metals and oil from cars. Sustainable Drainage Systems (SuDS) are a drainage concept that aims to mimic the pre-development hydrology by constructing systems to pass rain water back into the ground or store it, and then release it slowly back into rivers. Often this involves creating grass channels and wetlands, which can create attractive urban areas, habitat for animals and plants and also trap and remove pollutants. SuDS are one of the components of the Green Infrastructure ideal.

Research has shown that SuDS can deliver these "ecosystem services" and design guidance has been developed. However the SuDS often have a higher land take than traditional piped drainage, a concern to housing developers. They also have very different, often poorly understood, maintenance requirements. There is also uncertainty about their longevity and how to manage any long term accumulation of pollutants. Water Companies "adopt" piped drainage, but in England the long term adoption and payment for SuDS is uncertain. Planning guidance and legislation requiring SuDS to be included in schemes and adopted by local authorities has also been watered down as part of the Government's lighter touch planning policy. This means that achieving the additional benefits of lower pollution in rivers, improved urban environment and increased biodiversity are dependent on SuDS being able to be economically attractive to developers. However there are no standard guidelines for this economic evaluation and different schemes use different methods and boundaries for calculations. Therefore valuation of SuDS needs be standardised so that schemes can be compared, the appropriate amount of land allocated for high quality designs and to give confidence to property professionals in project appraisal.

This project will work with stakeholders, including developers, regulators and SuDS designers to arrive at best practice guidance for calculating the capital costs of SuDS, quantifying the economic values to developments (e.g. house prices, willingness to pay for upkeep by residents) and to explore what other contributions can be sought for off-site benefits. Key partners will be the Royal Institution of Chartered Surveyors (RICS) who provide professional guidance to quantity surveyors and valuation surveyors. We will work with RICS to create a professional Guidance Note and test this against case study projects. In addition to this valuation toolkit, training materials will be developed and delivered to surveying professionals.

The overall aim is to increase the uptake of high quality SuDS designs through synthesising and translating the environmental, social and engineering benefits in a way that allows their inclusion in decision-making processes. The University of Portsmouth team is made up of engineers who have studied the technical aspects of SuDS for over 20 years and valuation surveyors who have experience of valuing social and environmental services. This multidisciplinary team are therefore well placed to deliver this innovative project.

Planned Impact

The main outcome of the project will be to increase the uptake of high quality SuDS designs as part of Green Infrastructure strategies that will deliver multiple benefits to the UK - through improved flood protection; higher quality surface water; improved urban landscape; improved urban habitat and biodiversity; health improvements due to increased access to public open space; and more resilient urban infrastructure. Moreover, high quality SuDS can directly affect the habitus of residents and also have benefits for those living off site, particularly those living hydrologically downstream.

These broad and cross cutting benefits are to be delivered by facilitation of the economic case for including SuDS in developments by engaging with a range of stakeholders to develop standardised valuation guidance, endorsed by RICS, the professional body that accredits valuation surveying professionals. A lack of standardised valuation guidance, especially relating to ecosystem services and property values, has been identified as a limitation to the full exploitation of the research and case based evidence concerning the benefits of SuDS. Standardisation will enable professions such as Quantity Surveyors to engage with SuDS in a confident and efficient manner, facilitating the mainstream acceptance of Green Infrastructure as assets to be valued and also to enable the relationship between property values and SuDS amenity to be assessed in a standard framework.

The benefits to developers are that the economic case can be estimated with confidence using standard methods. This will mean that masterplans can be presented to planners and regulators with reference points to accepted practice and, it is hoped, that the broad value of SuDS will be apparent and demonstrated. Public planning authorities and regulators are potentially major beneficiaries, as a standardised economic case that can consider social and environmental externalities, will mean that officers will have a standard framework for assessing projects, improving efficiency in times of reduced capacity and allowing the quality of design to be considered more fully in planning decisions. This compares to current situations where unscrupulous rogue developers are able to select the economic analysis that best fits their goals and present extended legal arguments.

Although proposing an intervention based on economic standardisation, the project team believe that this is a leverage point for realising the potential of SuDS research to deliver multiple environmental benefits.

Publications

10 25 50
 
Description We have developed the understanding of residents perceptions of living with Sustainable Drainage Systems to help inform how developers might promote their use. We have quantified the financial saving possible in planning by including high quality SuDS designs, undertaken a hedonic pricing analysis of how living near green Sustainable Drainage affcets house price and after reviewing costs of Sustainable Drainage developed a costing tool to be used by developers.
Exploitation Route We are in discussions with the Royal Institute of Chartered Surveyors as to if any of this forms the basis for a professional guidance document. We are also disseminating through CPD events.
Sectors Construction,Environment

 
Title Survey of Residents, Local Authorities and Practicioners 
Description 3000 surveys of residents distributed and 380 returned concerning their relationship with SuDS. 28 (9 returns) local planning authorities interviewed about SuDs in planning and 3 practitioners (ongoing) 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? No  
Impact ongoing 
 
Description Article in RICS Land Journal 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact An article was written and published to raise awareness of the project among chartered surveyors, who are the target audience of the research outcomes.
Year(s) Of Engagement Activity 2016
URL http://www.isurv.com/site/scripts/documents_info.aspx?documentID=9828
 
Description CPD Course 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact RICS CPD Course for Property Professionals
Year(s) Of Engagement Activity 2017
 
Description Presentation at conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact ProSuDS outcomes were presented the Royal Institution of Chartered Surveyors Planning and Development Conference by CoI David Hutchinson. This is primarily a forum for planners and developers.
Year(s) Of Engagement Activity 2018
 
Description Presentation at conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact ProSuDS findings were presented at the Constructed Wetland Association annual conference by the PI. This organisation includes practitioners and academics. The conference was hosted at Portsmouth and one of the case study sites was used as the site visit as part of the conference guided by a member of the project steering group.
Year(s) Of Engagement Activity 2018
URL https://www.constructedwetland.co.uk/
 
Description Presentation at national conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact SuDS Net is a platform for academics and practitioners in the field of Sustainable Drainage. The PI of ProSuDS was asked to present a keynote address on the project but unfortunately was unable to attend. CoI, Cletus Moobela, presented on the overall project findings which was well received.
Year(s) Of Engagement Activity 2018
URL https://www.abertay.ac.uk/business/services/sudsnet/
 
Description RICS ACCREDITED CPD COURSE 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact CPD course delivered to about 20 property professionals from the South East region. This covered a range of technical and economic issues related to ProSuDS. Excellent feedback was received, reporting a raised awareness of the factors affecting SuDS uptake..
Year(s) Of Engagement Activity 2017
URL http://www.port.ac.uk/learning-at-work/short-courses-for-land-property-and-construction-professional...
 
Description Steering Committee 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Steering Group Meeting
Year(s) Of Engagement Activity 2017
 
Description Steering Group Meeting 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact A steering group meeting was held on 2/2/17 at RICS HQ with senior SuDS practitioners from local authorities, water companies, developers and designers.
Year(s) Of Engagement Activity 2017