P17

IN SITU FIELD PERFORMANCE MONITORING OF AIR INJECTION GROUND WATER REMEDIATION TECHNOLOGIES

The saturated zone bundles provide information on ground water temperature and displacement and concentration of dissolved oxygen for use in defining the volume of influence of air injection systems. The vadose zone bundles provide information on soil gas oxygen concentration. Both bundles also provide access to discrete sampling locations for the collection of grab samples during system evaluation.

Field data were gathered at a site with a subsurface characterized by heterogenous sand, silt, and clay. Thirty-four of the sensor bundles were located around the point of injection to provide a comparison of the development of air flow pathways among nine short duration field IAS trials. The sample collection and instrumentation bundle system have been used to monitor injection phases of 30 minutes followed by 7-day recovery phases.

The data collection system has indicated that air channels develop from the injection point to the monitoring points in as short as one minute but do not develop in the same order for each trial. Temporary mounding of the ground water, characterized by changes in hydrostatic head, is measurable in each case.

Key words: air sparging, monitoring, dissolved oxygen