How It Works?

This system utilizes a specially designed probe that will withstand the rigors of percussion probing while taking continuous measurements of soil conductivity and contaminate screening as it is being driven into the ground. The sensing probe is linked to a control box where the signal is received from a stringpot by a lap top computer. The stringpot, which is mounted on the probe, senses movement of the probe, and measures the precise depth of the probe. The signal from the probe is matched with this precise depth measurements, logged on the screen, and recorded in a Windows-based software used to provide a real-time display of conductivity versus depth and probing speed versus depth. The data is also stored in spreadsheet compatible format for later graphing and analysis. The consultant is able to read real time data showing changes in soil conductivity/resistivity. These changes can be used to identify lithology, contaminant plumes, salt water intrusion, or any other subsurface condition that displays a change in conductivity/resistivity.

The Membrane Interface Probe (MIP) is a screening tool with semi-quantitative capabilities acting as an interface between the contaminates in the subsurface and gas phase detectors at the surface. The membrane is semi-permeable and is comprised of a thin film polymer impregnated into a stainless steel screen for support. The membrane is approximately 6.35mm in diameter and may be easily replaced. The membrane is placed in a heated block attached to the probe. This block is heated to approximately 100-120 degrees C and is raised at the leading edge to protect the membrane. Heating the block helps accelerate diffusion of the contaminate through the membrane.

Diffusion occurs because of a concentration gradient between the contaminated soil and the clean carrier gas behind the membrane. A constant gas flow of 35-45 mL/min sweeps behind the membrane and carries the contaminants to the gas phase detectors at the surface. Travel time from the membrane interface to the detector(s) is approximately 30-45sec (depending on the length of trunkline and flow rate).

Presentations

Membrane Interface Probe

Battelle Poster Presentation

Learn About Conductivity