In-situ permeability measurements with direct push techniques: Phase II topical report

This effort designed, fabricated, and field tested the engineering prototype of the Cone Permeameter{trademark} system. The integrated system includes the instrumented penetrometer probe, air and water pumps, flowrate controls, flow sensors, and a laptop-controlled data system. All of the equipment is portable and can be transported as luggage on airlines. The data system acquired and displays the process measurements (pressures, flows, and downhole temperature) in real time and calculates the resulting permeability. The measurement probe is a 2 inch diameter CPT rod section, incorporating a screened injection zone near the lower end of the rod and multiple sensitive absolute pressure sensors embedded in the probe at varying distances from the injection zone. Laboratory tests in a large test cell demonstrated the system's ability to measure nominally 1 Darcy permeability soil (30 to 40 Darcy material had been successfully measured in the Phase 1 effort). These tests also provided a shakedown of the system and identified minor instrument problems, which were resolved. Supplemental numerical modeling was conducted to evaluate the effects of layered permeability (heterogeneity) and anisotropy on the measurement system's performance. The general results of the analysis were that the Cone Permeameter could measure accurately, in heterogeneous media, the volume represented by the sample port radii if the outer pressure ports were used. Anisotropic permeability, while readily analyzed numerically, is more complicated to resolve with the simple analytical approach of the 1-D model, and will need further work to quantify. This phase culminated in field demonstrations at the DOE Savannah River Site. Saturated hydraulic conductivity measurements were completed at the D-Area Coal Pile Runoff Basin, and air permeability measurements were conducted at the M Area Integrated Demonstration Site and the 321 M area. The saturated hydraulic conductivity measurements were the most successful and compared well to relevant existing data. Air permeability measurements were more problematic, primarily due to clay covering pressure measuring ports and preventing pressure communication with the sensors. Very little discreet air permeability data existed for the sites.