Relationship Between OVA Readings and Air Toxic Emissions from Soil Vapor Extraction Remediation Systems

Abstract

Soil Vapor Extraction (SVE) is considered an acceptable method for the remediation of petroleum impacted soils by the State of Florida. Typically, SVE involves applying a vacuum to the vadose zone by a mechanical system to collect volatile organic compounds (VOCs) present in the soil pore space. The collected VOCs include air toxics that are Hazardous Air Pollutants (HAPs). In order to comply with the federal air quality regulations, Florida has instituted a number of policies and procedures concerning HAP emissions from SVE systems. One of the policies includes the collection of off -gas samples for laboratory analysis of HAPs and other compounds. From the laboratory results and estimated air flow rates, an estimate of HAP emissions can be calculated. Unfortunately, as with most laboratory tests, analytical costs are high. They can cost between $125 and $150 per sample. As a result, off -gas sample collection for laboratory analysis occurs sparingly, usually only a few times over the durati on of a site’s remedial system operational life. Almost all of the SVE sites in Florida include routine (weekly, monthly, etc.) visits as part of the site’s operation & maintenance plan. During these visits, maintenance personnel frequently use an organic vapor analyzer (OVA) meter to screen the system’s off-gas for organic compounds. A study was made on the possibility of using these OVA readings as a supplement to the laboratory analyses with respect to HAP emissions. However, using information from ten (10) separate petroleum cleanup sites located in Broward County, Florida, statistical data analysis shows no significant correlation between OVA readings and contaminant concentrations (maximum R 2 value of 0.26). Thus, the use of OVA data for either comp liance testing or performance testing of SVE systems is not recommended.