Conflicts about groundwater contamination can be resolved using groundwater modeling and optimization techniques. At Toms River, New Jersey, disagreements among stakeholders regarding the appropriate design of a groundwater remediation strategy were resolved by using optimal-design techniques to demonstrate the infeasibility of designs that required certain physical limitations. Through negotiations in a series of public meetings wherein the results of these analyses were presented, a hydraulic containment design was eventually adopted and implemented by all stakeholders. The question remained, however, as to whether an alternative strategy based on acceptable risk rather than total plume containment would be appropriate. A new approach that permits investigation of this alternative strategy indicates that a design using risk-based constraints could be considerably different from that currently implemented. The analysis also demonstrates the relative cost of considering containment by hydraulic gradient versus risk reduction through mass removal. In the former, environmental risk is minimized by assuring an inward gradient around the plume perimeter. In the latter, the goal is to control risk while removing contaminant mass.