Citation:

Impact/Purpose:

The objective of this project is to develop an analytical method which uses thermal desorption (200 - 300 degreesC) to extract and accurately measure VOCs in soil and sediment samples to satisfy the EPA and state regulatory program requirements. Thermal extraction will be examined because the technique is a simpler and more efficient extraction technique than the present EPA purge methods. VOCs shall be detected and quantified by a gas chromatograph/mass spectrometer (GC/MS). Thermal extraction is also presently used for extracting semivolatile compounds in soil samples by RCRA Method 8275A. Such use encourages investigation of this technique for the quantification of both VOCs and semivolatile compounds. It is anticipated that the semivolatile compounds shall be analyzed by a second GC/MS, making it a dual GC/MS method.

Description:

A majority of the contaminated sites within the United States contain volatile organic compounds (VOCs), either as industrial chlorinated solvents or petroleum products commonly referred to as BTEX (benzene, toluene, ethyl benzene, and xylene). The present EPA methods for low level VOC analyses (RCRA Methods 5035A and the CLP method), commonly referred to as volatile organic analyses (VOA) are very matrix dependent and therefore can be biased low. The VOCs diffuse into the micropores or are adsorbed onto the soil matrix. This negative method bias can result in false negative situations where significant contamination may go undetected. Also, water soluble compounds are a major problem with the present methods because their low purging efficiencies result in high detection levels. Risk assessment is a crucial component of the site remediation decision-making process. The present EPA low level methods are not capable of measuring many VOCs at the required levels for risk assessment, EPA Region 3 Risk Based Concentration (RBC) levels, EPA Region 9 Preliminary Remediation Goals (PRG) levels, or the state clean up levels. Recently at a University of Massachusetts Remediation Conference, a paper was presented on the magnitude of the problem and concluded that resolving this issue is critical for human health and ecological risk assessments. It is critical that the EPA develop a method to accurately measure trace VOCs for the CLP Superfund program, RCRA and Brownfields site redevelopments, and the various state programs in Region 1. Some of the sites within New England where risk assessments are problematic include: Woburn, MA Wells G & H, Otis Air Force Base, and Nyanza, MA. A VOC target list has been developed for this project with the compounds identified that have low RBC and PRG quantitation levels.

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