Bioremediation geocomposite articles, and their method of manufacture, for treating (digesting) contaminats in soil or water. The bioremediating geocomposite mat includes a woven or non-woven geotexile, having a thickness of about 6 mm to about 200 mm. In the preferred embodiment, outer layers of the geocomposite article have a porosity sufficient to receive a powdered or granular contaminant-reactive material, contaminat-sorptive material, or a contaminant-neutralizing material in at least outer portions of the thickness across its entire major surface(s) for better contact of the bacteria with contaminants held by the powdered or granular material. In the most preferred embodiment, liquid-permeable cover sheets are adhered to the upper and lower major surfaces of the bacterial-containing geotextile article to prevent a powdered or granular material from escaping from the geotextile during transportation and installation.