Abstract: The treatment system involves the use of hydrofracturing in drilled boreholes over the treatment area. The hydrofracturing fluid contains treatment material, of the kind that causes chemical breakdown of the contaminant. The breakdown leads to a contaminant concentration of zero in the hydrofracks, and therefore the contaminant diffuses towards the hydrofracks, where it is in turn broken down. Calculations and measurements indicate whether natural cracks in the ground are far enough apart to make hydrofracturing worthwhile. A formula indicates, from an assessment of diffusion coefficients, etc, whether the contaminant will be rendered safe within a given time period.