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Michael Adam
Technology Integration and Information Branch
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Vapor Intrusion

Site Investigation Tools

There are many tools available to environmental practitioners for investigating a site for vapor intrusion. As with any site investigation, an important first step is to develop a conceptual site model (CSM). A CSM is a picture and narrative of the site contamination: how it got there, whether or not it is migrating or degrading, its distribution across the site, who might be exposed to it, and what risk-reduction strategies are most feasible. CSM development begins during the Phase I environmental site assessment with collection and evaluation of site history and reconnaissance information. The CSM is then augmented and refined, throughout subsequent site investigation activities with site-specific information on source areas, contaminant properties, stratigraphy, hydrogeology, exposure pathways, and potential receptors. Some older sites may not have a CSM for vapor intrusion, even where the remedial investigation and remedial design/remedial action or even construction complete stages have been accomplished. As a result, CSMs are being developed during the five-year review process at many Superfund sites to assess the potential for vapor intrusion where other contaminated media are being addressed.

For developing a CSM for vapor intrusion, EPA recommends a multiple lines of evidence approach, which may mean collecting a variety of samples (e.g., soil gas, groundwater, sub-slab, crawl space, indoor and outdoor air), assessing the building construction and ventilation systems, and identifying possible background and indoor sources of contaminants. Where field measurements are limited, mathematical models also may be used as a line of evidence in refining the CSM. The following sections summarize these lines of evidence and provide resources for further information.

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Sampling and Analysis

Trace Atmospheric Gas Analyzer (TAGA) Mobile Laboratory

Collecting samples for chemical analysis is the primary way in which a CSM is augmented and refined with site-specific data. Sampling not only helps evaluate the amount of contamination present beneath or inside a building, it can help environmental practitioners identify the source and extent contamination, possible receptors, and risk levels. The sampling tools and analytical techniques selected for an investigation will depend, in a large part, on the current CSM. The table below summarizes the advantages and disadvantages of the various options for sampling: groundwater, bulk soil, soil gas, sub-slab soil gas, and indoor air.

Inside the TAGA Mobile Laboratory

Groundwater Sampling

Vapor Intrusion Pathway: A Practical Guide
Interstate Technology & Regulatory Council, 172 pp, January 2007.

Step 8 of ITRC’s 13-step approach to evaluating vapor intrusion is choosing an investigative strategy. The guidance provides information on selecting various elements of a vapor intrusion investigative strategy, such as groundwater, soil, soil gas, sub-slab, indoor air, crawl space, and ambient air sampling. It also details supplemental tools such as emission flux chambers, tracers, differential pressure measurements, real-time and continuous analyzers, forensic data, meteorological data, and pneumatic testing.

Reference Handbook for Site-Specific Assessment of Subsurface Vapor Intrusion to Indoor Air
Electric Power Research Institute, 264 pp, March 28, 2005.

Provides guidance on the site-specific assessment of the significance of subsurface vapor intrusion into indoor air. Topics covered include theoretical considerations, sampling and analysis considerations, mathematical modeling, suggested methods for data collection, and suggested methods for data collection, including soil gas, sub-slab, groundwater, indoor air, outdoor air, and meteorological monitoring.

Groundwater Sampling and Monitoring Using Direct Push Technologies
U.S. Environmental Protection Agency, 78 pp, August 2005.

Explains groundwater sampling issues related to use of direct push technology, in particular those regarding the quality and usability of the groundwater data.

Recommendations for the Investigation of Vapor Intrusion (ESTCP Project ER-0423)
Thomas McHugh, 23 pp, April 2008.

Recommends approaches to collecting groundwater and soil gas samples to generate data suitable for pathway screening and a field investigation program to provide a cost-effective and timely evaluation of the presence or absence of vapor intrusion impacts.

Advancing a Soil Gas Probe

Soil Gas Sampling

Vapor Intrusion Pathway: A Practical Guide
Interstate Technology & Regulatory Council, 172 pp, January 2007.

Collecting and Interpreting Soil Gas Samples from the Vadose Zone: A Practical Strategy for Assessing the Subsurface Vapor-to-Indoor Air Migration Pathway at Petroleum Hydrocarbon Sites,
American Petroleum Institute, API publication 4741, 2005.

Provides in-depth information on issues associated with soil gas sampling and data interpretation
as applied to pathway assessment for sites contaminated with petroleum hydrocarbons.

Reference Handbook for Site-Specific Assessment of Subsurface Vapor Intrusion to Indoor Air
Electric Power Research Institute, 264 pp, March 28, 2005.

DOD Vapor Intrusion Handbook, The Tri-Service Environmental Risk Assessment Workgroup,
172 pp, January 2009

Guidance from the Department of Defense includes discussion of sampling soil, groundwater, soil gas, sub-slab, and indoor air for vapor intrusion sites as well as the influence of building design parameters.

Review of Best Practices, Knowledge and Data Gaps, and Research Opportunities, for the U.S. Department of Navy Vapor Intrusion Focus Areas
T. McAlary et al, 86 pp, May 2009.

Provides a review by a team of subject-matter experts of current best practices, opinions on the current state of knowledge and data gaps, and offers suggestions for research directions for the following three Navy-identified VI focus areas:

Sub-surface sampling for complete determination of VI pathway to minimize the need for intrusive sub-slab sampling;
Passive indoor air sampling methods to improve VI exposure estimates; and
Indoor air source separation to determine if indoor air contamination is from VI or indoor sources.

Petroleum Vapor Intrusion Literature List — Soil Gas Sampling
U.S. EPA, Office of Underground Storage Tanks website, 2011

U.S. Environmental Protection Agency, Office of Underground Storage Tanks (2011) has prepared this online resource with a vapor-intrusion literature list for sampling soil gas at petroleum sites.

Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab
U.S. Environmental Protection Agency, 326 pp, August 2009.

Field study conducted at Installation Restoration Program Site 14 on Naval Air Station Lemoore, California to assess the vertical and horizontal distribution of volatile organic compounds in the subsurface and to develop a database of paired macro-purge and micro-purge soil gas sample measurements. In addition, sampling was conducted to evaluate the performance of a variety of soil gas probe construction materials (tubing types) and to test passive diffusion samplers.

Recommendations for the Investigation of Vapor Intrusion (ESTCP Project ER-0423)
Thomas McHugh, 23 pp, April 2008.

Comparison of Geoprobe® PRT and AMS GVP Soil-Gas Sampling Systems with Dedicated Vapor Probes in Sandy Soils at the Raymark Superfund Site
EPA/600/R-06/111, U.S. Environmental Protection Agency, 79 pp, November 2006.

Documents study conducted near the Raymark Superfund Site in Stratford, Connecticut to compare results of soil-gas sampling using dedicated vapor probes, a truck-mounted direct-push technique - the Geoprobe Post-Run-Tubing (PRT) system, and a hand-held rotary hammer technique - the AMS Gas Vapor Probe kit.

Passive Soil Gas Survey

DOD Vapor Intrusion Handbook
The Tri-Service Environmental Risk Assessment Workgroup, 172 pp, January 2009.

Guidance from the Department of Defense includes discussion of sampling soil, groundwater, soil gas,
sub-slab, and indoor air for vapor intrusion sites as well as the influence of building design parameters.

Review of Best Practices, Knowledge and Data Gaps, and Research Opportunities for the U.S. Department of Navy Vapor Intrusion Focus Areas
T. McAlary et al, 86 pp, May 2009.

Sub-surface sampling for complete determination of VI pathway to minimize the need for intrusive sub-slab sampling;
Passive indoor air sampling methods to improve VI exposure estimates; and
Indoor air source separation to determine if indoor air contamination is from VI or indoor sources.

Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab
U.S. Environmental Protection Agency, 326 pp, August 2009.

Field study conducted at Installation Restoration Program Site 14 on Naval Air Station Lemoore, California to assess
the vertical and horizontal distribution of volatile organic compounds in the subsurface and to develop a database
of paired macro-purge and micro-purge soil gas sample measurements. In addition, sampling was conducted to
evaluate the performance of a variety of soil gas probe construction materials (tubing types) and to test passive
diffusion samplers.

Advancing a Sub-Slab Soil Gas Probe

Sub-Slab Sampling

Vapor Intrusion Pathway: A Practical Guide
Interstate Technology & Regulatory Council, 172 pp, January 2007.

Sub-Slab Sampling

Assessment of Vapor Intrusion in Homes Near the Raymark Superfund Site Using Basement and Sub-Slab Air Samples
EPA/600/R-05/147, Dominic C. DiGiulio, et al. 131 pp, 2006.

Describes the results of an investigation conducted to assist EPA’s New England Regional Office in evaluating vapor intrusion at 15 homes and one commercial building near the Raymark Superfund Site in Stratford, Connecticut. Methods were developed to sample sub-slab air and use both basement and sub-slab air measurements to evaluate vapor intrusion on a building-by-building basis.

Reference Handbook for Site-Specific Assessment of Subsurface Vapor Intrusion to Indoor Air
264 pp, March 28, 2005.

Canisters v. Sorbent Tubes: Vapor Intrusion Test Method Comparison
Joseph Odencrantz, Harry O`Neill, and James Kirkland, in Proceedings of the Sixth International Battelle Conference: Remediation of Chlorinated and Recalcitrant Compounds, 7 pp, May 2008.

The results from each method revealed a linear relationship between molecular weight and the difference in concentration between the two methods. The TO-17 results were generally lower than the TO-15 results for PCE.

The Use of Tracer Gas in Soil Vapor Intrusion Studies
Peter Reynolds, in Proceedings of the Annual International Conference on Soils, Sediments, Water, and Energy, Vol. 12, Issue 1, Article 39, 7 pp, January 15, 2010.

Discusses the use of tracer gas to verify that sub-slab samples do not contain ambient air.

Evaluation of Spatial and Temporal Variability in VOC Concentrations at Vapor Intrusion Investigation Sites
Thomas McHugh, Tim Nickels, and Samuel Brock, in Proceedings of Air & Waste Management Association’s Vapor Intrusion: Learning from the Challenges, 14 pp, September 2007.

Discusses the representativeness of sub-slab samples given temporal and spatial concentration variability.

DOD Vapor Intrusion Handbook
The Tri-Service Environmental Risk Assessment Workgroup, 172 pp, January 2009.

Guidance from the Department of Defense includes discussion of sampling soil, groundwater, soil gas,
sub-slab, and indoor air for vapor intrusion sites as well as the influence of building design parameters.

Review of Best Practices, Knowledge and Data Gaps, and Research Opportunities for the U.S. Department of Navy Vapor Intrusion Focus Areas
T. McAlary et al, 86 pp, May 2009.

Provides a review by a team of subject-matter experts of current best practices, opinions on the current state of knowledge and
data gaps, and offers suggestions for research directions for the following three Navy-identified VI focus areas:

Sub-surface sampling for complete determination of VI pathway to minimize the need for intrusive sub-slab sampling;
Passive indoor air sampling methods to improve VI exposure estimates; and
Indoor air source separation to determine if indoor air contamination is from VI or indoor sources.

Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab
U.S. Environmental Protection Agency, 326 pp, August 2009.

Field study conducted at Installation Restoration Program Site 14 on Naval Air Station Lemoore, California to assess the
vertical and horizontal distribution of volatile organic compounds in the subsurface and to develop a database of paired
macro-purge and micro-purge soil gas sample measurements. In addition, sampling was conducted to evaluate the
performance of a variety of soil gas probe construction materials (tubing types) and to test passive diffusion samplers.

Temporal Variation of VOCs in Soils from Groundwater to the Surface/Subslab: APM 349
Elliot, J., G. Swanson, and B. Hartman.
EPA 600-R-10-118, 143 pp, October 2010

This report presents the activities, results, findings, and recommendations associated with monitoring the variations in active soil vapor sample results near and under a slab adjacent to Building 170 at Naval Air Station Lemoore from November 2008 through October 2009. The work described in this report follows up on EPA's 2009 report, Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab.

Sampling Indoor Air with Summa Cannister

Indoor Air Sampling

Vapor Intrusion Pathway: A Practical Guide
Interstate Technology & Regulatory Council, 172 pp, January 2007.

Step 8 of ITRC’s 13-step approach to evaluating vapor intrusion is choosing an investigative strategy. The guidance provides information on selecting various element s of a vapor intrusion investigative strategy, such as groundwater, soil, soil gas, sub-slab, indoor air, crawl space, and ambient air sampling. It also details supplemental tools such as emission flux chambers, tracers, differential pressure measurements, real-time and continuous analyzers, forensic data, meteorological data, and pneumatic testing.

Soil Vapor and Air Sampling Bags

Vapor Intrusion Sampling Options: Performance Data for Canisters, Badges, and Sorbent Tubes for VOCs
Linda S. Coyne, George Havalias, and Maria C. Echarte, in Proceedings of the Air & Waste Management Association’s Vapor Intrusion 2009 Conference, 9 pp, San Diego, California, January 27-30, 2009

Discusses results of two field studies comparing Summa canisters, passive sampling badges, and sorbent tubes. The study found good correlation between the canisters and the other two methods and concluded that sorbent-based sampling devices can be used effectively in vapor intrusion studies as a reliable alternative to canister sampling.

Reference Handbook for Site-Specific Assessment of Subsurface Vapor Intrusion to Indoor Air
264 pp, March 28, 2005.

DOD Vapor Intrusion Handbook
The Tri-Service Environmental Risk Assessment Workgroup, 172 pp, January 2009.

Recommendations for the Investigation of Vapor Intrusion (ESTCP Project ER-0423)
Thomas McHugh, 23 pp, April 2008.

Recommends approaches to collecting groundwater and soil gas samples to generate data suitable for pathway
screening and a field investigation program to provide a cost-effective and timely evaluation of the presence or
absence of vapor intrusion impacts.

Guidance for Environmental Background Analysis, Volume IV: Vapor Intrusion Pathway
Naval Facilities Engineering Command (NAVFAC), UG-2091-ENV, 153 pp, April 2011.

This guidance document provides instructions for evaluating background conditions in vapor intrusion investigations. The background analysis techniques presented in this document are based on exploratory, forensic, and statistical methods. The guidance recognizes the unique features of vapor intrusion investigations and treats the recommended methods as "multiple lines of evidence" that should be considered when determining whether volatile chemicals measured in indoor air should be attributed to subsurface releases, indoor air background, or possibly both.

Analytical Methods

Compendium Method TO-15: Determination of Volatile Organic Compounds (VOCs) In Air Collected In Specially-Prepared Canisters and Analyzed By Gas Chromatography/Mass Spectrometry (GC/MS), Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air Second Edition
EPA/625/R-96/010b, U.S. Environmental Protection Agency, January 1999.

Documents sampling and analytical procedures for the measurement of subsets of the 97 volatile organic compounds
that are included in the 189 hazardous air pollutants listed in Title III of the Clean Air Act Amendments of 1990.

Use of Field Analytics to Solve Vapor Intrusion Issues
Dave Mickunas, presentation at the Fall 2005 Meeting of EPA’s Technical Support Project. San Antonio, TX. October 2005.26

Predictive Modeling

Predictive computer models are useful tools for examining the potential for vapor intrusion to occur at a property, particularly when limited field measurements can be collected. However, the results must be used with caution as their uncertainty increases with the uncertainty of the data input. In the absence of adequate field measurements, models require that data input be based on assumptions made about the conceptual site model (e.g., concentrations of contaminants, complexity of the site geology/hydrogeology, and characteristics of the building). Models can yield a wide range of results depending on these assumptions.

A commonly used, screening-level model for assessing vapor intrusion is the Johnson and Ettinger or “J&E” model. This model simulates one-dimensional diffusion of soil gas through unsaturated soil and both diffusion and advection through the building foundation. The J&E model is based on a number of simplifying assumptions regarding contaminant distribution and occurrence, subsurface characteristics, vapor transport, and building construction. The J&E model should be used only when site conditions match the model assumptions using reasonable, site-specific, or regulator-approved input.

Vapor Intrusion Screening Level (VISL) Calculator (MS Excel)
U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI), 2012

The U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI) developed a spreadsheet tool that: (1) lists chemicals considered to be volatile and sufficiently toxic through the inhalation pathway; and (2) provides VISLs for groundwater, soil gas and indoor air, which are generally recommended, media-specific, risk-based screening-level concentrations. The primary purpose of the VISL calculator is to assist Superfund site managers and risk assessors in determining, based on an initial comparison of site data against the VISLs: whether chemicals found in groundwater or soil gas can pose a significant risk through vapor intrusion; and, if so, whether a site-specific vapor intrusion investigation is warranted. Other Agency cleanup programs may also find it helpful to consider the VISLs for their own specific needs. VISL Users Guide

Heuristic Model for Predicting the Intrusion Rate of Contaminant Vapors into Buildings
P.C. Johnson and R. A. Ettinger, in Environmental Science & Technology, 25(8), 7 pages, August 1991.

Presents the Johnson & Ettinger Model for contaminant partitioning and subsurface vapor transport into buildings.

Screening Level Implementation of the Johnson and Ettinger Vapor Intrusion Model: Reverse Calculation of Target Media Concentrations

Online calculator implements the Johnson and Ettinger (J&E) simplified model to evaluate the vapor intrusion pathway into buildings. This J&E model replicates the implementation that the U.S. EPA Office of Solid Waste and Emergency Response used in developing its draft vapor intrusion guidance, but includes a number of enhancements that are facilitated by web implementation: temperature dependence of Henry's Law Constants, automatic sensitivity analysis of certain parameters, and others.

User’s Guide for Evaluating Subsurface Vapor Intrusion into Buildings
U.S. Environmental Protection Agency, 133 pp, February 22, 2004.

Provides documentation and instructions for using the Johnson and Ettinger model for estimating subsurface vapor intrusion into buildings. Includes accompanying spreadsheets.

Simulation of the Vapor Intrusion Process for Non-Homogeneous Soils Using a Three-Dimensional Numerical Model
Ozkur Bozkurt, Kelly Pennell, and Eric Suuberg, in Groundwater Monitoring and Remediation, 29(1), 12 pp, January 1, 2009.

Presents model simulation results of vapor intrusion into structures built atop sites contaminated with volatile or semi-volatile chemicals of concern

Effect of Vapor Source-Building Separation and Building Construction on Soil Vapor Intrusion as Studied with a Three-Dimensional Numerical Model
Lilian D.V. Abreu and Paul C. Johnson, in Environmental Science &Technology. Volume 39, 11 pp, 2005.

Describes a three-dimensional numerical model of the soil vapor-to-indoor air pathway developed and used as a tool to anticipate not-yet-measured relationships between the vapor attenuation coefficient, α(indoor air concentration/source vapor concentration), and vapor source−building lateral separation, vapor source depth, and building construction characteristics (depth of building foundation) for nondegrading chemicals. The numerical model allows for diffusive and advective transport, multi-component systems and reactions, spatially distributed foundation cracks, and transient indoor and ambient pressure fluctuations.

Simulating the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into Buildings: Influence of Degradation Rate, Source Concentration, and Depth
Lilian D.V. Abreu and Paul C. Johnson, Environ. Sci. Technol., 40 (7), 11 pp, 2006.

Article in Environmental Science & Technology looks at steady-state vapor intrusion scenarios involving aerobically biodegradable chemicals are studied using a three-dimensional multi-component numerical model. (View abstract.)

Conceptual Model Scenarios for the Vapor Intrusion Pathway
Lilian Abreu, presented at the U.S. Environmental Protection Agency Vapor Intrusion Workshop, AEHS Conference, March 2010.

Slide presentation describes Abreu and Johnson three-dimensional vapor intrusion model, vapor fate and transport mechanisms, and the effect of site conditions on vapor intrusion.

Effect of Vapor Source-Building Separation and Building Construction on Soil Vapor Intrusion as Studied with a Three-Dimensional Numerical Model
L.D. Abreau and P.C. Johnson, in Environmental Science and Technology 39(12), 11 pp, June 15, 2005.

Describes a three-dimensional numerical model of the soil vapor-to-indoor air pathway used as a tool to anticipate not-yet-measured relationships between the vapor attenuation coefficient, alpha (indoor air concentration/source vapor concentration), and vapor source-building lateral separation, vapor source depth, and building construction characteristics (depth of building foundation) for non-degrading chemicals.

The Influence of Transient Processes on Vapor Intrusion Processes
Y. Yao, K.G. Pennell, E.M. Suuberg, presented at Proceedings of the Air & Waste Management Association’s Vapor Intrusion 2010 Conference, 9 pp, September 29-30, 2010.

A three-dimensional vapor intrusion model was used to investigate the time required to reach steady-state vapor intrusion rates. The effect of pressure fluctuations on vapor intrusion rates was also investigated. These results were obtained for a homogenous soil conceptual site model with groundwater located at 25 feet below ground surface. The results provide insight about managing and characterizing vapor intrusion risks.

Vadose Zone Profiling to Better Understand Vadose Zone Processes Related to Vapor Intrusion
Daniel Carr, Laurent Levy, and Allan Horneman, 15 pp, 2010.

Examines vadose zone processes and high resolution characterization as a means of refining site-specific conceptual models for vapor intrusion investigations.

Reference Handbook for Site-Specific Assessment of Subsurface Vapor Intrusion to Indoor Air
264 pp, March 28, 2005.

Review of Best Practices, Knowledge and Data Gaps, and Research Opportunities for the U.S. Department of Navy Vapor Intrusion Focus Areas
T. McAlary et al, 86 pp, May 2009.

Sub-surface sampling for complete determination of VI pathway to minimize the need for intrusive sub-slab sampling;
Passive indoor air sampling methods to improve VI exposure estimates; and
Indoor air source separation to determine if indoor air contamination is from VI or indoor sources.

Petroleum Vapor Intrusion Literature List — Characterization
U.S. EPA, Office of Underground Storage Tanks website, 2011

U.S. Environmental Protection Agency, Office of Underground Storage Tanks (2011) has prepared this online resource with a vapor-intrusion literature list for characterizing VI at petroleum sites. This section contains many citations related to predictive modeling.

A Comparison of the Johnson-Ettinger Vapor Intrusion Screening Model Predictions with Full Three-Dimensional Model Results
Y. Yao, et al., in Environmental Science & Technology, February 23, 2011.

Predictions from a three-dimensional model of vapor intrusion, based upon finite element calculations of homogeneous soil scenarios, are directly compared with the results of the J−E model. These results suggest that there are conditions under which the J−E model predictions might be quite reasonable but that there are also others in which the predictions are low as well as high.

Uncertainty and the Johnson-Ettinger Model for Vapor Intrusion Calculations
EPA/600/R-05/110, James Weaver and Fred Tillman, U.S. EPA National Exposure Research Laboratory, 43 pp, September 2005.

Software with automated uncertainty analysis was applied to the Johnson-Ettinger model that accounted for synergistic effects among variable model parameters. The analysis showed that a simple “one-at-a time” parameter uncertainty analysis provides a rough guide for the uncertainty generated by individual parameters and allowed their ranking, but underestimated the uncertainty in the model results when all or groups of parameters were assumed
to be uncertain.

Review of Recent Research on Vapor Intrusion
EPA/600/R-05/106, Fred D. Tillman and James Weaver, U.S. EPA National Exposure Research Laboratory, 47 pp, September 2005.

Reviews research in the area of vapor intrusion of organic compounds into residential buildings including; challenges in evaluating the subsurface-to-indoor air pathway, fate and transport mechanisms affecting vapors, Federal regulations and proposed guidance, site studies published in scientific literature, and published approaches to modeling.

Simulating the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into Buildings: Evaluation of Low Strength Sources Associated with Dissolved Gasoline Plumes
Lilian D.V. Abreu, Robert Ettinger, and Todd Mcalary,
American Petroleum Institute Publication 4775, 64 pp, January 2009.

Building Design

HVAC Influence on Vapor Intrusion in Commercial and Industrial Buildings
David Shea, Claire Lund, and Bradley Green, in Proceedings of the Air & Waste Management Association’s Vapor Intrusion 2010 Conference, 12 pp, 2010.

This paper presents an overview of common HVAC components and how they influence indoor air quality. Several case studies are presented describing the role of HVAC operations in vapor intrusion assessment and mitigation. Favorable and unfavorable effects of HVAC operations on vapor intrusion also are given.

DOD Vapor Intrusion Handbook
The Tri-Service Environmental Risk Assessment Workgroup, 172 pp, January 2009.

Review of Best Practices, Knowledge and Data Gaps, and Research Opportunities for the U.S. Department of Navy Vapor Intrusion Focus Areas
T. McAlary et al, 86 pp, May 2009.

Surface sampling for complete determination of VI pathway to minimize the need for intrusive sub-slab sampling;
Passive indoor air sampling methods to improve VI exposure estimates; and
Indoor air source separation to determine if indoor air contamination is from VI or indoor sources.

Vapor Intrusion in Urban Settings: Effect of Foundation Features and Source Location
Yijun Yao, Kelly G. Pennell, Eric Suuberg, in Procedia Environmental Sciences, Vol. 4, pp 245–250, 2011.

A 3-D computational fluid dynamics model is used to investigate how the presence of impervious surfaces affects vapor intrusion rates. To complement modeling efforts, the investigators are in the initial stages of conducting a field study in a neighborhood where vapor intrusion is occurring.

Pneumatic Conductivity Testing

Pneumatic testing to measure soil vapor permeability of soil or floor slab can be used to help refine the conceptual site model for vapor intrusion at a site or optimize the design of mitigation systems.

Pneumatic Testing, Mathematical Modeling and Flux Monitoring to Assess and Optimize the Performance and Establish Termination Criteria for Sub-Slab Depressurization Systems (PowerPoint presentation)
Todd McAlary, David Bertrand, Paul Nicholson, Sharon Wadley, Danielle Rowlands, Gordon Thrupp and Robert Ettinger, Geosyntec Consultants, Inc., Presented at the U.S. EPA workshop, “Addressing Regulatory Challenges in Vapor Intrusion: A State-of-the-Science Update Focusing on Chlorinated VOCs,” held at the Association for Environmental Health and Sciences 21st Annual Meeting and West Coast Conference on Soils, Sediments, and Water - Workshop: Addressing Regulatory Challenges in Vapor Intrusion, San Diego, California March 15, 2011

Presentation slides include explanation of how to calculate the pneumatic conductivity of a building’s floor slab.

Vapor Intrusion Pathway: A Practical Guide, Interstate Technology & Regulatory Council
172 pp, January 2007.

Includes discussion of the utility of and how to conduct pneumatic tests for the investigation of vapor intrusion.

Standard Test Method for Measurement of Pneumatic Permeability of Partially Saturated Porous Materials by Flowing Air, The American Society for Testing and Materials
Vol. 04.09, ASTM D 6539-00, 2006.

This test method covers laboratory determination of the coefficient of permeability for the flow of air (pneumatic permeability) through partially saturated porous materials.

Meteorological Monitoring

Vapor Intrusion Pathway: A Practical Guide
Interstate Technology & Regulatory Council, 172 pp, January 2007.

Reference Handbook for Site-Specific Assessment of Subsurface Vapor Intrusion to Indoor Air
264 pp, March 28, 2005.

Forensic Approaches

A Guide for Assessing Biodegradation and Source Identification of Organic Ground Water Contaminants Using Compound Specific Isotopes Analysis (CSIA)
EPA 600/R-08/148, U.S. Environmental Protection Agency, 82 pp, December 2008.

Intended for managers of hazardous waste sites who must design sampling plans that will include CSIA and specify data quality objectives for CSIA analyses, for analytical chemists who must carry out the analyses, and for staff of regulatory agencies who must review and approve the sampling plans and data quality objectives, and who must review the data provided from the analyses.

Use of Compound Specific Stable Isotope Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs: Laboratory Validation Report
McHugh, T., T. Kuder, M. Klisch, and R.P. Philp.
ESTCP Project ER-201025, 59 pp, 2012

The objective of this study was an empirical validation of selected adsorbents for preconcentration of TCE, PCE, and benzene in air samples containing low concentrations of these VOCs. For validation of adsorbent tube performance, the investigators selected adsorbent-analyte pairings likely to offer good quantitative recovery of the target VOCs. Results demonstrate fractionation-free performance for Carboxen 1016, which allows precise isotope ratio analysis into vapor intrusion site assessment protocols and other applications where VOCs of interest are present at low microgram-per-cubic-meter concentrations.

Use of Compound Specific Stable Isotope Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs: Laboratory Validation Report
McHugh, T.E., L.M. Beckley, D.M. Bailey, K. Gorder, E.M. Dettenmaier, I. Rivera-Duarte, S. Brock, and I. MacGregor.
Environmental Science & Technology 46(9):4792-4799(2012)

Comparison of VOC concentrations in indoor air measured during the negative and positive pressure test conditions was sufficient to determine whether VI was the primary source of VOCs in indoor air at 5 buildings. Results indicate that sampling under controlled building pressure can help minimize ambiguity caused by both indoor sources of VOCs and temporal variability in VI investigations. Longer abstract

Use of CSIA to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs
Thomas McHugh et al. Proceedings of the Air & Waste Management Association’s Vapor Intrusion 2009 Conference,
8 pp, San Diego, California, January 27-30, 2009.

Discusses a study at Hill Air Force Base to determine if compound-specific isotope analysis can be used to differentiate between TCE found in groundwater and soil gas from indoor TCE sources.

Vapor Intrusion Pathway: A Practical Guide
Interstate Technology & Regulatory Council, 172 pp, January 2007.

Guidance for Environmental Background Analysis, Volume IV: Vapor Intrusion Pathway
Naval Facilities Engineering Command (NAVFAC), UG-2091-ENV, 153 pp, April 2011.

Site Investigation Case Studies

Characterizing TCE Exposure Distribution for Occupants of Houses with Basements
Wanyu Chan, Gregory Brorby, and Brian Murphy, 13 pp, September 2010.

Applied the two-compartment modeling approach to a group of 13 single-family houses situated above a trichloroethene (TCE) groundwater plume to estimate the exposure distribution for occupants residing in houses with a basement. Exposure predictions were compared to the conservative assumption that the measured TCE concentrations in the basement are representative throughout the whole house. This analysis characterizes two important parameters used to evaluate exposure to elevated TCE concentrations in the basement.

Detailed Field Investigation of Vapor Intrusion Processes (ESTCP Project ER-0423)
GSI Environmental, 338 pp, September 2008.

Demonstration study by Department of Defense to identify a cost effective and accurate protocol for investigation of vapor intrusion into buildings overlying contaminated groundwater.

Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab
U.S. Environmental Protection Agency, 326 pp, August 2009.

An Evaluation of Vapor Intrusion into Buildings Through a Study of Field Data
Nancy Fitzpatrick and John J. Fitzgerald, presented at the11th Annual Conference on Contaminated Soils University of Massachusetts at Amherst, 17 pp, October 1996.

Systematic examination of cases on file with the Massachusetts Department of Environmental Protection undertaken to identify a universe of VOC contaminated sites in close proximity to buildings. Locations were grouped according to site variables, such as contaminants of concern and concentrations in various media; soil type; depth to groundwater; distance to building; and building construction.

Evaluation of Vapor Intrusion from a Subsurface Diesel Plume Using Multiple Lines of Evidence
John Connor, Farrukh Ahmad, and Thomas E. McHugh, 15 pp.

A series of investigations were conducted near a railway facility in Mandan, North Dakota, where organic vapors had been detected in both the subsurface and in indoor air. The results of this investigation demonstrate how multiple lines of evidence, including statistical cluster analysis, can be employed to distinguish between background indoor air quality and organic vapors associated with actual subsurface vapor intrusion.

Results and Lessons Learned Interim Report: Altus AFB Site
Groundwater Services, Inc. for the Department of Defense ESTCP, 110 pp, July 7, 2005.

Demonstration study to identify and validate site investigation scope that provides the most accurate and reliable evaluation of vapor intrusion at corrective action sites by:

Collecting a high density of data related to vapor intrusion;
Analyzing this data to obtain a thorough understanding of vapor intrusion processes; and
Evaluating subsets of the data that reflect various options for conducting a limited scope vapor intrusion investigation to determine which subset provides the most accurate indication of the actual vapor intrusion at the site.

JV Task 86 – Identifying the Source of Benzene in Indoor Air Using Different Compound Classes
from TO-15 Data
Steven B, Hawthorne, 45 pp, April 2007.

DOE document evaluates volatile organic compound data collected using EPA method TO-15 at four different sites to determine whether the source of indoor air benzene was outdoor air or vapor intrusion. The findings indicated the indoor air contamination was probably from outdoor air and not the contaminated soils.

Recommends for the Investigation of Vapor Intrusion (ESTCP Project ER-0423)
Thomas McHugh, 23 pp, April 2008.

Generate data suitable for pathway screening and a field investigation program to provide a cost-effective and timely evaluation of the presence or absence of vapor intrusion impacts.

Innovations in Site Characterization: Streamlining Cleanup at Vapor Intrusion and Product Removal Sites Using the Triad Approach: Hartford Plume Site, Hartford, Illinois
EPA 542-R-10-006, U.S. Environmental Protection Agency, 143 pp, September 2010.

Vapor intrusion from widespread hydrocarbon plumes at the site resulted in numerous fires and forced residents to move from their homes. The EPA Region 5 Emergency Response Team's OSCs worked with area oil companies to address the public concerns at the site quickly. The project team used Triad approach best management practices to expedite investigation, mitigation, and cleanup processes. The extent of contamination was defined in roughly two years, and an existing mitigation system was augmented and optimized. Further augmentation of the mitigation and remedial/corrective action systems is ongoing. Refinement of the mitigation and remedial design at the site is ongoing as of September 2010.

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