[en] Groundwater flow velocity is a critical parameter in evaluating the field performance of in-situ permeable reactive barriers. Laboratory column tests indicate that bromide is a suitable studies involving granular iron. Conservative tracer tests conservative tracer for use in field tracer studies have been conducted to determine groundwater velocity and flow patterns through pilot-scale funnel-and-gate trials involving the EnviroMetal Process. Other methods of measuring in-situ velocities have also been evaluated. Once accurate groundwater flow velocities are known and concentrations of VOCs are measured, field degradation rates can be calculated. Both parameters are necessary for the design and costing of full-scale treatment systems