Development of the SEAMIST(trademark) concept for site characterization and monitoring. Final report

摘要

SEAMIST(trademark) (Science and Engineering Associates Membrane Instrumentation and Sampling Technique) is a borehole liner and instrument emplacement technique with applications in contaminant monitoring and site characterization. The system incorporates an impermeable tubular membrane which is deployed in a borehole by inversion under pneumatic pressure. Once in place the membrane remains under internal pressure to support the borehole wall and seal the hole against air circulation. Instruments and sampling devices mounted on the surface of the membrane are pressed against the borehole wall to maintain intimate contact with the geologic media. The membrane is left pressurized with air for short term applications (less than a month, for example) or filled with sand for longer term semi-permanent installations. This effort developed the SEAMIST(trademark) system explicitly for vadose zone gas and pore fluid sampling in monitoring circumstances of particular interest to the DOE. The emplacement hardware, membrane materials, sampling components, and ancillary equipment were fabricated and field tested. Absorbent collector materials were shown in laboratory tests to wick water samples at metric potentials as high as 15 bars. Soil vapor sampling tubing and fittings were tested with the deployment system to assess their integrity during the emplacement process and achievable sampling rates. A technique for measuring effective gas permeability at multiple elevations in the borehole was analyzed and tested in the field.