Skip common site navigation and headers
United States Environmental Protection Agency
Exposure Research
Begin Hierarchical Links EPA Home > Research & Development > Exposure Research > Publications/Presentations > End Hierarchical Links

 

To Purge or Not to Purge? VOC Concentration Changes During Line Volume Purging

spacer
spacer
Abstract:Soil vapor surveys are commonly used as a screening technique to delineate volatile organic compound (VOC) contaminant plumes and provide information for soil sampling plans. Traditionally, three purge volumes of vapor are removed before a sample is collected. One facet of this study was to evaluate the VOC concentrations lost during purging and explore the potential implications of those losses. The vapor data was compared to collocated soil data to determine if any correlation existed between the VOC concentrations.

Two different methods for soil vapor collection were compared: 1) active/micro-volume; and 2) active/macro-volume. The active/micro-volume vapor sample had total line purge volume of 1.25 mL and the active/macro-volume vapor sample had a total line purge volume of 15 mL. Six line purge volumes were collected for each vapor sampling technique, with the fourth purge volume representing the traditional sample used for site screening data. Each sample was collected by gas tight syringe and transferred to a thermal de sorption tube for sorption, transport, and analysis. Following the removal of the soil vapor samples, collocated soil samples were taken.

For both active vapor sampling techniques, the VOC concentrations in the first three purge volumes exceeded the VOC concentrations in the last three purge volumes. This implies that the general rule of removal of three purge volumes prior to taking a sample for analysis could lead to underestimating the level of VOC contamination present. At one of the sampling locations, the data show a general increase in concentration of VOCs as line volume purges were collected. The data did not show a correlation between the concentration of VOCs determined by either vapor sampling technique when compared to that of the collocated soil sample.
spacer
Citation:Zimmerman, J. H., and B. A. Schumacher. To Purge or Not to Purge? VOC Concentration Changes During Line Volume Purging. Presented at National Environmental Monitoring Conference, Washington, DC, July 19-22, 2004.
spacer
spacer
Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
spacer
Division: Environmental Sciences Division
spacer
Branch: Characterization & Monitoring Branch
spacer
Product Type: Abstrct/Oral
spacer
Presented: 07/19/2004
spacer
Related Entries:
spacer
Bullet Item Soil and Sediment Sampling Methods
spacer Relationship Reason:   A Project of the Product
spacer
spacer
spacer

 

ORD Home | Search EPA | Search NERL | Search EIMS | Contacts | Help

 
Begin Site Footer

EPA Home | Privacy and Security Notice | Contact Us

Last Updated on Monday, October 22, 2007
URL: http://cfpub.epa.gov