Abstract: A groundwater treatment system for collecting a non-aqueous-phase liquid (NAPL) in a flow path of contaminated water in a body of water, the contaminated water moving toward a permeable reactive barrier (PRB) including a treatment agent for treating the contaminated groundwater. The groundwater treatment system including a collection layer positioned up-gradient of the PRB and permeable to the NAPL and the contaminated water. The collection layer including a NAPL collecting element to inhibit the NAPL from flowing to the PRB.

Abstract: Devices and methods for preventing migration of buoyant contaminants from subaqueous contaminated sediment while providing for venting of gas that migrates from the contaminated sediment are described.

Abstract: A method for reducing leaching and bioaccessibility of a heavy metal from particulate matter includes the steps of treating the particulate matter with phosphate, chloride and iron additives; wetting the additive-containing particulate matter with water; and incubating the particulate matter at a temperature above ambient temperature for a time sufficient to achieve the goals of the invention.

Abstract: A method for treating a recalcitrant organic contaminant in contaminated soil or waste includes the steps of (1) maintaining indigenous bacteria or microbes in the contaminated soil or waste at a population level below which the indigenous bacteria or microbes are able to interfere with the enzyme while the enzyme acts against the contaminant and (2) exposing the contaminated soil or waste to an enzyme for a time sufficient to decrease the amount of the recalcitrant organic contaminant in the soil or waste. If the soil or waste also includes one or more readily degradable organic chemical, the method can include the additional step of reducing the content of the readily degradable organic chemical in the soil or waste.