An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

Abstract

a b s t r a c tThe practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems. This was accomplished by coupling the system dynamics-based decision support system CARO-PLUS to the aquatic ecosystem model AQUATOX using an analytical volatilization model for the stream. The model was applied to a case study where a trichloroethylene (TCE)-contaminated groundwater plume is discharging to a stream. The TCE source will not be depleted for many decades; however, measured and predicted TCE concentrations in surface water were found to be below human health risk management targets. Volatilization rapidly attenuates TCE concentrations in surface water. Thus, only a 30-m stream reach fails to meet surface water quality criteria. An ecological risk assessment found that the TCE contamination did not impact the stream ecosystem. Uncertainty assessment revealed hydraulic conductivity to be the most important site-specific parameter. These results indicate that contaminant plumes with g L −1 concentrations of TCE entering surface water systems may not pose a significant risk.

Heterogeneous hyporheic zone dechlorination of a TCE groundwater plume discharging to an urban river reach

“…Plumes may also be lengthy due to their modest natural attenuation in many aquifer environments (McGuire et al, 2004). As such, dissolvedphase CHC plumes may hold significant potential to discharge to surface waters where they may pose risks to ecosystems and human receptors (Conant et al, 2004;McGuire et al, 2004;McKnight et al, 2010;Moran et al, 2007;Weatherill et al, 2014). Our focus is upon the final opportunity for natural attenuation of discharging CHC groundwater contaminants at the groundwater -surface water interface (GSI) and hyporheic zone therein.…”

Dilution and volatilization of groundwater contaminant discharges in streams

“…Due to the implementation of the European Water Framework Directive (WFD) and the increasing exploitation of stream water and groundwater, an increasing effort is made to understand the linkage between these two systems and assesses the effect of groundwater contaminants on surface water ecosystems and chemical quality (Hancock 2002;McKnight et al 2010;Schmidt et al 2010;McKnight et al 2012). Proper tools for quantification of pollutant transport from groundwater seepage into streams and the inherent transport and dilution are essential for risk assessment and management of groundwater -surface water systems affected by contaminated sites.…”

“…Field experimental studies have attempted to identify the surface water -groundwater interaction zones, quantify the inflow (Westbrook et al 2005;Milosevic et al 2012), and study the processes in the sediment bed during groundwater seepage (e.g., Conant et al 2004;Bianchin et al 2006;Chapman et al 2007;Ellis and Rivett 2007;McKnight et al 2010;Milosevic et al 2012). In field studies the contaminant discharged from a groundwater plume was rarely detected in the stream due to rapid dilution by clean stream water and there is little published work on the resultant concentration distribution along the stream.…”

“…In field studies the contaminant discharged from a groundwater plume was rarely detected in the stream due to rapid dilution by clean stream water and there is little published work on the resultant concentration distribution along the stream. In this study the developed models are compared to the field data provided by McKnight et al (2010) and Nielsen et al (2014) from two Danish streams.…”

Territorial-Technical and Socio-Economic Aspects of Successful Brownfield Regeneration: A Case Study of the Liberec Region (Czech Republic)

“…the future uses of brownfields), implying that these tools will only be utilized once the most significant decisions, that is, the future functions of the areas, have been made. Currently, this condition must already be fulfilled when using holistic assessment methods (Carlon et al, 2007;Schädler et al, 2011;Wedding & Crawford-Brown, 2007), but also methods that only assess one particular aspect of the regeneration -for example the effect on population health (McKnight et al, 2010), or regeneration costs (Bayer, Finkel & Teutsch, 2005).…”