A permeable barrier for decontaminating groundwater having two distinct components for increasing contaminant removal. Preferably, the barrier material is a mixture or distinct layers of bone-char phosphate material and iron oxide pellets. The barrier material can be incorporated as part of a shallow trenching decontamination system, or incorporated in a non-pumping well, or array of non-pumping wells, as part of a deep underground decontamination system. The system can be used for removing, among other things, a radionuclide, such as uranium, from water.