System for treating contaminated groundwater

Procedure for treating contaminated groundwater in-situ in its native aquifer, wherein:

• the procedure includes the step of determining the nature of, the extent of, and the velocity of, a plume of dissolved contaminant within a body of groundwater travelling through an aquifer;
• the procedure includes the step of selecting and providing a body of active material;
• the procedure includes the step of forming, in the material of the aquifer, a receptacle or cavity which is suitable for receiving the body of active material, and of placing the said body in the receptacle;
• the procedure includes the step of so locating the said receptacle that the active material therein lies in the path of the plume;
• the arrangement of the receptacle being such that the plume enters the receptacle through an upstream side thereof, and emerges from the receptacle through a downstream side thereof, the arrangement being such that natural gradients of the aquifer in which the receptacle is located cause the plume of contaminated groundwater to pass from the aquifer into the receptacle, pass through the receptacle from side to side thereof, and emerge into the aquifer from the downstream side thereof;
• the body of active material in the receptacle is of such porosity and permeability that resistance to the passage of groundwater through the receptacle and through the body of material in the receptacle is substantially no greater than the resistance of the native aquifer to the passage of groundwater through the aquifer;
• the body of active material is active in the sense that the presence of the material in substance causes the dissolved contaminant to be removed from the groundwater;
• the chemical or biochemical nature of the active material in relation to the chemical or biochemical nature of the contaminant is such that at least prolonged operative contact of the groundwater with the active material is effective to cause a change in the oxidation-reduction state by chemical or biochemical reaction of at least a substantial proportion of the dissolved contaminant into a substance which is substantially solid and insoluble in the groundwater, and which is retained in the active material.