An impact assessment methodology for urban surface runoff quality following best practice treatment

The paper develops an easy to apply desk-based semi-quantitative approach for the assessment of residual receiving water quality risks associated with urban surface runoff following its conveyance through best practice sustainable drainage systems (SUDS). The innovative procedure utilises an integrated geographical information system (GIS)-based pollution index approach based on surface area impermeability, runoff concentrations/loadings and individual SUDS treatment performance potential to evaluate the level of risk mitigation achievable by SUDS drainage infrastructure. The residual impact is assessed through comparison of the determined pollution index with regulatory receiving water quality standards and objectives. The methodology provides an original theoretically based procedure which complements the current acute risk assessment approaches being widely applied within pluvial flood risk management

Behaviour of selected emerging pollutants in stormwater best management practices (BMPs)

A range of emerging pollutants (EPs) are now being considered for regulatory designation as potentially hazardous or as priority substances. These EPs occur ubiquitously in urban receiving waters and have both point and non-point sources. The occurrence and likely sources of four selected EPs (diclofenac, perfluoro-octane sulphonic acid; PFOS, hexabromocyclododecane; HBCD and dichlorvos; DDVP) found in urban surface water discharges are discussed with reference to extreme events and CSO discharges. A unit operating process (UoP) methodology is utilised to evaluate primary BMP removal mechanisms and the susceptibility of the individual EPs to be removed by these processes based on their physico-chemical properties. Despite the prevailing low level concentrations encountered in urban runoff, the methodology provides a scientifically underpinned screening framework to identify the most appropriate BMP controls for the pollutant(s) under consideration. True source control approaches such as direct infiltration, green roofs, rain gardens and porous paving would appear to the moist effective management measures

Assessing the impact of Swales on receiving water quality

Swales are one type of sustainable drainage system (SuDS) which contribute to the management of water quality in receiving waterbodies. Using a semi-quantitative approach, an impact assessment procedure is applied to the residual water quality that is carried forward to surface waters and groundwaters following treatment within a swale. Both volumetric and pollutant distributions are considered as stormwater passes through the swale system. The pollutant pathways followed by TSS, nitrate, chloride, metals (Cd, Cu, Pb, Zn) and polyaromatic hydrocarbons (PAHs) are determined for a swale receiving highway runoff. For TSS, metals and PAHs between 20% and 29% of the total mean influent pollutant load is predicted to be directed to infiltration through the underlying soils compared to between 4% and 16% of chloride and nitrate. Although surface water impacts are deemed possible, the discharges of swales to groundwaters are assessed to represent a negligible impact for effectively maintained systems

An impact assessment for urban stormwater use

Stormwater has the potential to provide a non-potable water supply which requires less treatment than municipal wastewaters with the added benefit of reducing pollution and erosion issues in receiving water bodies. However, the adoption of stormwater collection and use as an accepted practice requires that the perceived risks, particularly those associated with public health, are addressed. This paper considers the human health concerns associated with stormwater quality when used for a range of non-potable applications using E. coli, a commonly found pollutant in urban stormwater which is also widely included in human health based water quality standards and guidelines. Based on a source-pathway-receptor model, scores are allocated, on a scale of 0 to 5, to benchmark increasing the likelihoods of exposure to stormwater during different occupational and non-occupational applications and magnitude of impacts which may result. The impacts are assessed by comparing median stormwater E. coli levels with the reported guideline levels relating to different stormwater uses. Combination of the exposure and impact scores provides an overall risk score for each stormwater application. Low or medium risks are shown to be associated with most stormwater uses except for domestic car washing and occupational irrigation of edible raw food crops where the predicted highest levels of risk posed by median E.coli levels in stormwater necessitate the introduction of remedial actions

Risk prioritisation of stormwater pollutant sources

This paper describes the development of a pollutant risk prioritisation methodology for the comparative assessment of stormwater pollutants discharged from differing land use types and activities. Guidelines are presented which evaluate available data with respect to ‘likelihood of occurrence’ and ‘severity of impact’. The use of the developed approach is demonstrated through its application to total suspended solids, biochemical oxygen demand, lead and cadmium. The proposed benchmarking scheme represents a transparent and auditable mechanism to support the synthesis of data from a variety of sources and is sufficiently flexible to incorporate the use of chemical, physical and/or ecological data sets. Practitioners involved in developing and implementing pollutant mitigation programmes are assisted in two key ways. Firstly through enabling the risks to receiving waters from diffuse pollution on a source-by-source and/or pollutant-by-pollutant basis at a catchment scale to be comparatively assessed and prioritised. Secondly, the methodology informs the selection of appropriate diffuse pollution control strategies

A risk assessment approach for prioritising stormwater control strategies.

An important element in considering alternative drainage strategies and options (and their subsequent implementation and management) is an assessment of associated risks and uncertainties. As a contribution to meeting this typically ‘wicked’ challenge, this paper presents a structured and systematic approach to evaluating data and information from a range of sources within a single framework which can be developed and applied using site or catchment specific information. This approach is described in detail and involves the development of ‘risk scores’ which enable identified risks to be prioritised, or ranked. The completion of this process provides a platform for the consideration of risks which may apply over a range of time-frames, providing an opportunity for risks identified to be addressed within current and/or longer-term urban planning policy and regulatory developments. The application of the approach in relation to an assessment of risks to stormwater planning associated with the Eastside Development, Birmingham, UK, is briefly discussed

An impact assessment for urban stormwater use

The adoption of stormwater collection and use for a range of non-potable applications requires that the perceived risks, particularly those associated with public health, are addressed. Pollutant impacts have been assessed using E. coli and a scoring system on a scale of 0 to 5 to identify the magnitude of impacts and also the likelihood of exposure to stormwater during different applications. Combining these identifies that low or medium risks are generally predicted except for domestic car washing and occupational irrigation of edible raw food crops where the predicted high risk would necessitate the introduction of remedial action

Development and application of an innovative approach to predicting pollutant concentrations in highway runoff

Recognising the challenges and limitations of current methodologies to predict highway runoff concentrations, this paper presents a novel approach based on the derivation of pollutant emission factors for twelve different types of vehicle. Published emission factor data and properties of differing vehicles types are combined with annual average daily traffic volume (AADT), highway characteristics and rainfall data to determine the pollutant distributions associated with differing highway and traffic types. In this paper, the method is applied to 126 sections of highway in the Greater London Borough of Enfield (United Kingdom; UK) and results are comparable with values reported in the literature. The approach is used to identify the level of AADT predicted to result in an exceedance of environmental quality standards (EQS), with results suggesting that runoff from highways experiencing AADT values as low as 5000 may require treatment prior to discharge to receiving waters. Future scenario analyses indicate that the impact of progressively replacing petrol and diesel vehicles with electric vehicles will have negligible impact on concentrations of zinc (Zn), copper (Cu), cadmium (Cd) and total suspended solids discharging from highway environments. The approach enables identification and ranking of urban highways in terms of their pollution runoff potential and provides an important support to users in prioritising locations for the installation of sustainable drainage options in order to protect receiving water environments. [Abstract copyright: Copyright © 2021. Published by Elsevier B.V.

Researching creatively with pupils in Assessment for Learning (AfL) classrooms on experiences of participation and consultation

This paper reports on an ESRC TLRP project, Consulting Pupils on the Assessment of their Learning (CPAL). The CPAL project provides an additional theoretical perspective to the ‘educational benefits’ perspective of engaging pupil voice in learning and teaching (Rudduck et al., 2003) through its exploration of pupil rights specifically in relation to assessment issues presently on the policy agenda in the Northern Ireland context – notably Assessment for Learning (AfL). An emergent framework for assessing pupil rights, based on Article 12 of the United Nations Convention on the Rights of the Child (Lundy, 2007), is being used to explore the ways in which AfL classroom practice creates the conditions for increased pupil participation and consultation. Pupil views on their AfL classroom experiences and participation are explored by means of a variety of pupil-centred, creative research methods that engage and stimulate pupils to observe, communicate and analyse their learning and assessment experiences and give meaning to them. This presentation highlights preliminary data based on a sample of 11-14 years pupils' experiences of participation and consultation in classrooms adopting AfL pedagogical principles, and identifies characteristics that support or inhibit pupil participation in their learning and the expression of their views about such matters

Towards a paradigm SWITCH: Integrating urban water management in Belo Horizonte, Brazil.

A prime objective of an integrated, holistic approach is to deliver more effective provision of water resource services carrying minimum risks and improved sustainability. This is the core mission of the 6th EU Framework project, “Sustainable Water Management to Improve Tomorrow’s Cities’ Health” (SWITCH). The focus of the innovative management approach will be centred in demonstration cities such as Belo Horizonte in Brazil, through the formation of strategic Learning Alliances (LAs) comprising organisations having a shared interest in and vision of future urban water management. The paper explores both the LA formation and the challenges to be faced in the negotiating process which will be concerned with expected issues and “pay-offs”, as well as opportunities and difficulties especially related to feasibility as opposed to sustainability