Environmental- and health-risk-induced remediation design for benzene-contaminated groundwater under parameter uncertainty: a case study in Western Canada.

This study proposes an environmental- and health-risk-induced remediation design approach for benzene-contaminated groundwater. It involves exposure frequency and intake rates that are important but difficult to be exactly quantified as breakthrough point. Flexible health-risk control is considered in the simulation and optimization work. The proposed approach is then applied to a petroleum-contaminated site in western Canada. Different situations about remediation durations, public concerns, and satisfactory degrees are addressed by the approach. The relationship between environmental standards and health-risk limits is analyzed, in association with their effect on remediation costs. Insights of three uncertain factors (i.e. exposure frequency, intake rate and health-risk threshold) for the remediation system are also explored, on a basis of understanding their impacts on health risk as well as their importance order. The case study results show that (1) nature attenuation plays a more important role in long-term remediation scheme than the pump-and-treat system; (2) carcinogenic risks have greater impact on total pumping rates than environmental standards for long-term remediation; (3) intake rates are the second important factor affecting the remediation system's performance, followed by exposure frequency; (4) the 10-year remediation scheme is the most robust choice when environmental and health-risk concerns are not well quantified.