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This guide provides a standardized protocol for the use of on-site gas chromatography/mass spectrometry (GC/MS) analysis to evaluate the potential for vapor intrusion in a building, including the ability to distinguish between vapor intrusion and indoor or other sources of volatile organic chemicals (VOCs). This vapor intrusion investigation approach provides an alternative to the conventional investigation method of indoor air and sub-slab testing using Summa canisters and off-site laboratory analysis. The protocol was developed and validated as part of Environmental Security Technology Certification Program (ESTCP) Project No. ER-201119 (GSI, 2013)., Prepared in collaboration with Hill AFB and with SSC Pacific.

Compound-specific stable isotope analysis (CSIA) can be used as a building-specific vapor intrusion investigation tool to augment data from other investigation methods. The primary utility is to provide an independent line of evidence to distinguish between vapor intrusion and indoor sources of VOCs. This CSIA protocol is not a standalone investigation approach. It involves collection of subsurface source (i.e., groundwater) and indoor air samples. Concentrations of target VOCs from these media must be known or estimated to develop CSIA sampling parameters (e.g., sample collection time). This document i) describes the applicability of CSIA for vapor intrusion investigations (Section 2.0), ii) provides a step-by-step procedure for sample collection (Section 3.0), and iii) includes guidelines for data interpretation (Section 4.0)., Prepared in collaboration with the University of Oklahoma, Norman

Indoor sources of VOCs are ubiquitous, resulting in detectable concentrations in indoor air, often at levels exceeding regulatory screening criteria. At corrective actions sites with potential vapor intrusion concerns, the presence of indoor VOC sources significantly complicates the exposure pathway evaluation. Because of these indoor sources, the detection of a site-related VOC in a potentially affected building does not necessarily indicate a vapor intrusion impact. However, because conventional investigation methods often do not clearly identify the source of VOCs, additional rounds of sampling are commonly required. The overall goal of this demonstration was to validate use of compound-specific stable isotope analysis (CSIA) to distinguish between vapor intrusion and indoor sources of VOCs. As part of this project, a step-by-step protocol has been developed which can be used to provide an independent line of evidence to determine whether or not buildings are impacted by vapor intrusion. Many elements, such as carbon, occur as different isotope species, differing in their number of neutrons present in the nucleus. For example, 12C, with 6 neutrons, is the most abundant form of carbon. 13C, with 7 neutrons, makes up a small fraction (1%) of the carbon in the environment. Isotopic ratios (13C/12C) of a specific compound (e.g., TCE) can vary as a result of differences in their source material or compound synthesis or due to transformation in the environment (USEPA, 2008). Differences in the isotopic ratio measured in organic contaminants present in environmental samples can be used to i) distinguish between different sources of the contaminants and ii) understand biodegradation and other transformation processes occurring in the environment. While CSIA has been applied to groundwater investigations, its applicability to vapor intrusion assessments has only recently been explored (e.g., McHugh et al., 2011)., Prepared in collaboration with the University of Oklahoma, Norman.

Distinguishing between vapor intrusion (VI) and indoor sources of volatile organic compounds (VOCs) is a significant challenge in site assessments, greatly increasing the cost and complexity of investigations. Rapid on-site analysis of indoor air samples using a portable GC/MS allows the users to understand the distribution of VOCs in real-time, supporting identification of the source while in still the field. The overall objective of the demonstration was to develop and validate a step-wise investigation procedure using commercially-available off the shelf (COTS) on-site GC/MS analysis with real-time decision making as a tool to distinguish between vapor intrusion and indoor sources of VOCs. Use of on-site GC/MS analysis to distinguish between vapor intrusion and indoor sources of VOCs requires a field-portable analytical instrument with sufficient sensitivity to measure VOC concentrations in indoor air within the concentration range of regulatory concern (i.e., as low as 1 g/m3). A high degree of precision is also required because the protocol relies on measuring concentration gradients inside a building to identify sources of VOCs. For the demonstration, we utilized a HAPSITE portable GC/MS instrument. Although specific procedures in the investigation protocol were developed using the HAPSITE, any on-site instrument with sufficient sensitivity and precision may be used in the protocol. The field investigation program included application of the on-site GC/MS analysis protocol at four Department of Defense (DoD) sites. To evaluate the validity of this investigation approach, we also conducted conventional vapor intrusion and compound-specific stable isotope analysis (CSIA; ESTCP Project ER-201025) investigations concurrently at the study sites. Results from the three investigation methods were compared to evaluate the relative effectiveness of the different investigation approaches. This report presents the results from a total of seven demonstration buildings., Prpeared in collaboration with Hill Air Force Base, UT, and GSI Environmental Inc., Houston, TX.

The overall objective of this research project has been to identify key sources of variability that influence volatile organic chemical \201VOC\202 concentration measurements in water samples collected from groundwater monitoring wells using current sampling and analysis techniques. By understanding the sources of variability in groundwater monitoring results improved sampling and analysis methods can be developed to reduce and control for sampling variability. Methods: The project has been implemented through completion of three project tasks 1. Evaluation of Existing Datasets \201Task 1\202: The initial project task utilized large existing groundwater monitoring datasets to identify key sources of variability in groundwater monitoring results. The data mining study involved i\202 identification of large databases of groundwater monitoring results, ii\202 selection of datasets from these databases that were suitable for statistical analysis, and iii\202 exploratory analysis and statistical analysis of the datasets to identify factors associated with monitoring variability. For this task, we identified three large groundwater monitoring databases: i\202 the Hill Air Force Base \201AFB\202 database, ii\202 the Marine Corps Logistics Base \201MCLB\202 Albany database, and iii\202 a database of monitoring results from 48 underground storage tank sites compiled by GSI. Because the Hill AFB database included the most comprehensive documentation, many of the analyses could only be conducted using the Hill AFB database. 2. Evaluation of Short-Term Variability \201Task 2\202: For this task, we characterized sources of short-term variability in groundwater monitoring results through a field program that involved collecting and analyzing a large number of groundwater samples from a set of monitoring wells over a short period of time., Pub. in GSI Environmental , p1-54, Dec 2012.

Project ER-0707 has validated two improved methods for evaluation of vapor intrusion at corrective action sites: i) a Tier 2 screening procedure for evaluation of vapor intrusion from VOCs in groundwater at sites with fine-grained soils at the top of the water table and ii) a streamlined Tier 3 investigation program using building pressure control for application at sites that require building-specific investigations., The original document contains color images.

Indoor sources of volatile organic chemicals (VOCs) are ubiquitous, resulting in detectable concentrations in indoor air, often at concentrations above regulatory screening levels. At VOC contaminated sites with potential vapor intrusion concerns, the presence of indoor VOC sources significantly complicates the exposure pathway investigation. Because of these indoor sources, the detection of a site-related VOC in a potentially affected building at a concentration above the regulatory screening level does not necessarily indicate a vapor intrusion impact. Instead, additional analysis is required to determine the sources of the detected VOCs. We have developed several approaches to distinguish between vapor intrusion and indoor sources of VOCs including: (i) use of a field-portable gas chromatograph/mass spectrometer (GS/MS) to evaluate the distribution of VOCs within a building and to identify specific indoor sources of VOCs, (ii) collection of indoor air and sub-slab soil gas samples under controlled negative building pressure conditions designed to maximize vapor intrusion and controlled positive building pressure conditions designed to inhibit vapor intrusion, and (iii) use of compound-specific stable isotope analysis to determine the original source of VOCs detected in indoor air samples. Each of these methods has been has been applied to one or more buildings potentially impacted by vapor intrusion and has proved useful to distinguish between vapor intrusion and indoor sources of VOCs., Prepared in collaboration with University of Oklahoma, Hill AFB, Navy SPAWAR, and BP America. Presented at the Annual Partners in Environmental Technology Technical Symposium & Workshop (15th), Washington, DC, 30 Nov - 2 Dec 2010. Sponsored by SERDP and ESTCP. U.S. Government or Federal Rights License