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GUIDELINES FOR INSTALLATION AND SAMPLING OF SUB-SLAB VAPOR PROBES TO SUPPORT ASSESSMENT OF VAPOR INTRUSION
Citation:
DIGIULIO, D. C. GUIDELINES FOR INSTALLATION AND SAMPLING OF SUB-SLAB VAPOR PROBES TO SUPPORT ASSESSMENT OF VAPOR INTRUSION. Presented at Groundwater Resources Association of California, San Jose, CA, May 25, 2005.
Impact/Purpose:
To inform the public.
Description:
The purpose of this paper is to provide guidelines for sub-slab sampling using dedicated vapor probes. Use of dedicated vapor probes allows for multiple sample events before and after corrective action and for vacuum testing to enhance the design and monitoring of a corrective measure (e.g., sub-slab depressurization). Guidelines presented here will be incorporated into USEPA's guidance on vapor intrusion and into a number of state (e.g., Colorado) guidance documents as well. The focus of this paper is on the mechanical aspects of sub-slab vapor probe installation and subsequent sampling for VOCs using Summa canisters and EPA Method TO-15 analysis and Tedlar bags using on-site gas chromatography analysis. Guidelines for sub-slab sampling of radon gas and analysis using scintillation cells are also discussed since radon has the potential to act as a ubiquitous conservative tracer to aid assessment of vapor intrusion. The methodology of probe installation and use of recommended materials to construct probes is outlined in detail. Relevant sample collection issues such as assessment of: minimum equilibration time after probe installation prior to sampling, minimum purge volume requirement prior to sampling, sample volume, leak testing during sampling, and restrictions on sample flow rate are thoroughly discussed from both a theoretical and practical perspective.