Abstract: A portable decontamination system including a carriage for carrying an operator and a decontamination unit is moved to the site of a truck mounted environmental well drilling rig. The carriage is displaced along the length of the substantially upright rig via a lift, whereupon the operator remotely operates the decontamination unit for washing the rig. Contaminated wash water resulting from washing the rig is caught in a pan for subsequent disposal, or decontamination and re-use, as the case may be.