of the shroud 58 which is maintained under negative pressure although the embodiment of the apparatus shown in fig2 creates an annular flow passageway it will be appreciated that in its broadest aspects the passageway need not be annular in cross section for example an i beam can be used instead of a round kelly and the flow passageway created by rotation of the i beam would comprise the essentially rectangular cross section areas between the flanges and web of the i beam although the present invention is concerned primarily with methods and apparatus for obtaining data concerning soil contamination when contaminants are found treatment may be dictated this treatment may consist of any combination of steps including the injection of additional hot air or steam for stripping of volatile contaminants injection of treatment chemicals or biological treatment media etc pressures of up to 5000 psi are typically used with fluids at temperatures usually exceeding 50 u00b0 c to liberate volatile contaminants concern has been expressed that such high pressures may result in the recontamination of soil in the block or cylinder of soil above the cutter or in the contamination of previously cut adjacent cylinders fig8 shows a plan view of the pattern of treatment of a contaminated soil area using a pair of overlapping counter rotating cutter injectors 65 65 39 enclosed in a single rectangular shroud 58 the frame 10.