CONTAMINATION AND MANAGEMENT OF THE BIRMINGHAM (UK) URBAN AQUIFER RESOURCE

Effective urban water-quality management requires integrated understanding of urban land, groundwater, baseflow and surface-water quality relationships. The City of Birmingham is the UK’s second largest city after London and has been a major industrial centre for the past two centuries, perhaps most famous for its metal manufacturing. It is located upon the Triassic sandstone, the UK’s second-most important aquifer unit. Chemical quality data from across the listed media above have been collected for the Birmingham aquifer – River Tame conurbation to assess chemical transport from contaminated land to groundwater to baseflow to surface water. Soils’ metals concentrations were elevated, however, low leachability and attenuation caused concentrations in groundwaters and baseflow discharging to surface water to be generally low with only sporadic elevated concentrations attributed to localised point sources. In relation to VOCs (volatile organic compounds), hydrocarbons were similarly absent or at low level that was attributed to their ready natural attenuation effective in this relatively low flow, high storage sandstone formation. Chlorinated VOCs, however, were widely encountered in groundwater, discharging as baseflow to surface water and marginally impacting surface-water quality. This is attributed to their DNAPL (dense nonaqueous-phase liquid) properties and relative recalcitrance, although there was some evidence of biodegradation and abiotic reactions for some chlorinated VOCs. Generic conclusions are drawn on urban water-quality management from this work and discussed within the context of: massive declines in groundwater abstraction from urban aquifers due to the UK decline of manufacturing industry; rebounding groundwater levels common in UK cities; rapid land-planning led re-development of contaminated “brownfield” sites; massive and un-fundable costs for full site remediations; and, the need to develop schemes that effectively utilize the urban, often sporadically contaminated, groundwater resource.