The use of constructed wetlands for the treatment of urban runoff

In 1995, the Environment Agency for England and Wales developed urban runoff treatment wetlands at two selected locations in Outer London. The systems have been monitored for a wide range of parameters including heavy metals, suspended solids and BOD over a period of two years. Seven storm events were also monitored. The ability of micro-organisms, isolated from the rhizosphere of wetland plants collected at both systems, to tolerate and accumulate heavy metals has also been investigated. This study has demonstrated that constructed wetland treatment systems are capable of reducing the pollutant loadings associated with urban runoff, and that such systems can be successfully established within urban areas. During dry weather, pollutant concentrations and loadings were typically low and associated removal efficiencies highly variable. However, during storm events, pollutant loadings increased and removal efficiencies improved, with mean removal efficiencies of 71% for Pb and 81% for Cr at the Dagenham wetland. An exception to this was for suspended solids which showed an overall increase of 99% during storm events. Several design and operational issues have been identified and addressed during the course of the monitoring programme, and recommendations for the improved design and operation of urban runoff treatment wetland systems have been made. A range of micro-organisms, isolated from both wetland systems, were able to tolerate elevated Zn and Pb concentrations. Two strains (Beauveria bassiana and Rhodotorula mucilaginosa) were selected for further work. Both strains could accumulate Zn and Pb, with B. bassiana showing a high capacity to bind Pb (maximum concentration of 136mgPb/g cells dry weight). Comparison of the growth of B. bassiana at 4°C and 30°C suggested that processes of microbial metal accumulation may occur throughout the year in treatment wetlands. The presence of Pb inside hyphae of B. bassiana, associated with hyphae walls and in the surrounding medium was confirmed. This study has found that micro-organisms isolated from urban runoff treatment wetlands can tolerate and accumulate Zn and Pb, and the application of these results to wetland treatment processes is discussed

A mixed methods approach to urban ecosystem services: experienced environmental quality and its role in ecosystem assessment within an inner-city estate

This paper contributes to the notion of ecosystem services (ES) and dis-services (EDS) through an exploration of how they are experienced in an inner-city neighbourhood. We contrast the findings of a science-led assessment with qualitative interview and visual data from the residents of the Woodberry Down Estate (London, UK). We use the ontology of co-production and co-construction to understand how material and interpretative factors condition the translation of identified service-providing units (SPUs) into directly experienced ES and EDS. Findings demonstrate that aspects contributing to the perceived liveability of a neighbourhood also condition the experienced ES and EDS. In our case study, the history of the estate translates into subjective feelings of safety which influence whether individuals access parts of the regenerated estate. While the regeneration project provides a broad range of new and improved SPUs with significant ES potential, the access and recreational functions these offer are especially appreciated for the increased opportunities for social interaction and visitors they provide. However, new SPUs such as landscape vistas and formal gardens that attract people are also assigned further significance as markers of new divisions among social housing residents. We suggest that in order to realise the much-prophesised health and wellbeing benefits of urban ES in an equitable manner, a science-led approach to designing and assessing potential ES should be accompanied by a context-sensitive assessment of community needs and liveability aspects

Implementing sustainable drainage systems for urban surface water management within the regulatory framework in England and Wales

The UK 2007 floods resulted in damages estimated to exceed over £4 billion. This triggered a national review of strategic flood risk management (Pitt, 2008) with its recommendations informing and implemented by the Flood and Water Management, Act (FWMA, 2010). Estimating that up to two-thirds of properties flooded in the 2007 event as a direct result of overloaded sewer systems, the FWMA set out an ambitious overhaul of flood risk management approaches including identifying bodies responsible for the management of local flood risk (local municipalities) and the development of over-arching Lead Local Flood Authorities (LLFAs) at a regional level. LLFAs duties include developing local flood risk management strategies and, aligned with this, many LLFAs and local municipalities produced sustainable drainage system (SUDS) guidance notes. In parallel, changes to the national planning policy framework (NPPF) in England give priority to the use of SUDS in new major developments, as does the related Town and Country Planning Order (2015). However, whilst all three pieces of legislation refer to the preferential use of SUDs, these requirements remain “economically proportionate” and thus the inclusion of SUDS within development controls remain desirable - but not mandatory - obligations. Within this dynamic policy context, reignited most recently by the December 2015 floods, this paper examines some of the challenges to the implementation of SUDS in England and Wales posed by the new regulatory frameworks. In particular, it examines how emerging organisational procedures and processes are likely to impact on future SUDS implementation, and highlights the need for further cross-sectoral working to ensure opportunities for cross-sectoral benefits– such as that accrued by reducing stormwater flows within combined sewer systems for water companies, property developers and environmental protection – are not lost

Exploring the Lived Experience of Decision-Making among Family Caregivers of Black Older Adults with Advanced Chronic Illnesses

This phenomenological study explored the lived experience of family caregivers\u27 making health care decisions with or for community-dwelling older Blacks with advanced chronic illnesses. Max van Manen’s interpretative phenomenological approach was used to understand the meaning of decision-making among participants. Semi-structured interviews were conducted with eleven family caregivers. Thematic analysis and interpretation of interviews revealed three essential themes: living out commitments with intention; making meaningful decisions situated in context; and reflecting on the past, anticipating the future. These essential themes culminated in an integrated interpretative statement: “Living out commitments with intentions of making or helping to make meaningful decisions that value the person, reflect past experiences, and anticipate the future.

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

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