In situ Soil Probe for Rapid Delineation of Dense Non Aqueous Phase Liquids

DESCRIPTION (provided by applicant): During this Phase I SBIR project, Dakota Technologies, Inc. (Dakota) will demonstrate that a simple solid state halogen specific detector can be miniaturized, hardened, and incorporated into a percussion deliverable probe capable of delineating dense non-aqueous phased liquids (DNAPL) in the subsurface in real time. The proposed system will be based on a halogen specific detector capable of detecting the halogenated volatile organic compounds (hVOCs) from which DNAPL is composed. The signals generated by the detector will be captured by a miniaturized charge integrator, developed by Dakota, which will also fit entirely within the confines of the direct push probe. The selected detector and electronics will be mated with a Membrane Interface Probe (MIP) developed by Geoprobe(r) Systems. By placing the detector directly behind the MIP, issues that continue to limit the performance of the standard embodiment of the MIP such as time lag for analytes to reach the detector and overloading problems will be eliminated. This unique combination will make continuous measurements of DNAPL and associated dissolved phase in both the vadose and saturated zones possible for the first time. Proof of concept will be established through laboratory studies designed to demonstrate the detector's specificity to hVOCs, monotonic behavior over a wide concentration range, immunity to changing subsurface conditions, and detector longevity under field conditions. After selecting the best detector and proving its performance in the lab, a fully functional prototype probe will be constructed and operated in a limited field trial. The field trial will demonstrate the system's ability to log DNAPL via percussion driven direct push platforms, providing an unprecedented understanding of DNAPL distribution in the subsurface. Detailed knowledge of DNAPL distribution is the main key to designing effective remediation strategies. The proposed system will provide environmental consultants, engineers, and regulators with the DNAPL distribution information they so desperately need to accomplish their difficult, but not impossible, task of remediating DNAPL sites. The ultimate beneficiaries of the research will be the citizens who rely on a supply of clean, healthy drinking water. For decades, chlorinated solvents have been used for many applications, including dry cleaning and metal degreasing. These solvents are carcinogenic and being denser than water, can travel down into the subsurface, ultimately reaching the groundwater aquifers used for much of the public's water supply. The proposed research will lead to a real time probe that can more accurately map the source term (NAPL) of these solvents in the subsurface, which will allow for faster and more effective cleanup, thereby minimizing the exposure of the public to these compounds.