Empirical Assessment of Ground Water–to‐Indoor Air Attenuation Factors for the CDOT‐MTL Denver Site

Johnson, Paul C.; Ettinger, Robert; Kurtz, J.; Bryan, R.J.; Kester, Janet E.

doi:10.1111/j.1745-6592.2008.01224.x

Cited by 12 publications

(12 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 4 shows the comparison between the bounding attenuation factor estimate presented above using equations (2) through (5) and measurements from the CDOT-MTL Denver Site (Kurz 2000; Foster et al 2004; Johnson et al 2002, 2009), where an intensive study was performed involving collections of groundwater, soil gas, and indoor air samples. Characterization of the dissolved ground water plume was based on a large number of data points and considered reasonably reliable.…”

Section: Validation Of the New Screening Levels With Field Datamentioning

confidence: 99%

See 1 more Smart Citation

Examining the Use of USEPA's Generic Attenuation Factor in Determining Groundwater Screening Levels for Vapor Intrusion

Yao

Verginelli

Suuberg

et al. 2018

Groundwater Monitoring Rem

View full text Add to dashboard Cite

A value of 0.001 is recommended by the United States Environmental Protection Agency (USEPA) for its groundwater-to-indoor air Generic Attenuation Factor (GAFG), used in assessing potential vapor intrusion (VI) impacts to indoor air, given measured groundwater concentrations of volatile chemicals of concern (e.g., chlorinated solvents). The GAFG can, in turn, be used for developing groundwater screening levels for VI given target indoor air quality screening levels. In this study, we examine the validity and applicability of the GAFG both for predicting indoor air impacts and for determining groundwater screening levels. This is done using both analysis of published data and screening model calculations. Among the 774 total paired groundwater-indoor air measurements in the USEPA’s VI database (which were used by that agency to generate the GAFG) we found that there are 427 pairs for which a single groundwater measurement or interpolated value was applied to multiple buildings. In one case, up to 73 buildings were associated with a single interpolated groundwater value and in another case up to 15 buildings were associated with a single groundwater measurement (i.e, that the indoor air contaminant concentrations in all of the associated buildings were influenced by the concentration determined at a single point). In more than 70% of the cases (390 of 536 paired measurements in which horizontal building-monitoring well distance was recorded) the monitoring wells were located more than 30 meters (and some up to over 200 meters) from the associated buildings. In a few cases, the measurements in the database even improbably implied that soil gas contaminant concentrations increased, rather than decreased, in an upward direction from a contaminant source to a foundation slab. Such observations indicate problematic source characterization within the dataset used to generate the GAFG, and some indicate the possibility of a significant influence of a preferential contaminant pathway. While the inherent value of the USEPA database itself is not being questioned here, the above facts raise the very real possibility that the recommended groundwater attenuation factors are being influenced by variables or conditions that have not thus far been fully accounted for. In addition, the predicted groundwater attenuation factors often fall far beyond the upper limits of predictions from mathematical models of VI, ranging from screening models to detailed computational fluid dynamic models. All these models are based on the same fundamental conceptual site model, involving a vadose zone vapor transport pathway starting at an underlying uniform groundwater source and leading to the foundation of a building of concern. According to the analysis presented here, we believe that for scenarios for which such a “traditional” VI pathway is appropriate, 10−4 is a more appropriately conservative generic groundwater to indoor air attenuation factor than is the EPA-recommended 10−3. This is based both on the statistical analysis of USEPA’s VI da...

show abstract

Section: Validation Of the New Screening Levels With Field Datamentioning

confidence: 99%

“…Comparison of groundwater attenuation factors between screening values and measurements from the CDOT-MTL Denver Site (Johnson et al 2009). …”

Section: Figurementioning

confidence: 99%

Examining the Use of USEPA's Generic Attenuation Factor in Determining Groundwater Screening Levels for Vapor Intrusion

Yao

Verginelli

Suuberg

et al. 2018

Groundwater Monitoring Rem

View full text Add to dashboard Cite

show abstract

“…Natural attenuation includes microbial degradation, physical processes (such as dispersion, dilution, and sorption), and chemical reactions or the stabilization of contaminants. Unlike CHCs, biodegradation of PHC vapors in subsurface soil has been described in numerous field studies (Ostendorf and Kampbell, 1991; Hers et al, 2000; Davis et al, 2002, 2009a; Morrill et al, 2005; Johnson et al, 2009), laboratory investigations (Jin et al, 1994; Pasteris et al, 2002; Ghazali et al, 2004; Höhener et al, 2006), and modeling studies (Karapanagioti et al, 2003; Abreu and Johnson, 2006; DeVaull, 2007; Abreu et al, 2009). There is also a large volume of literature describing NA phenomena (Azadpour‐Keeley et al, 2001; Karapanagioti et al, 2003; Mulligan and Yong, 2004; Schirmer and Butler, 2004; Clement et al, 2005; Smith and Lerner, 2007).…”

Section: Natural Attenuation and Model Parametersmentioning

confidence: 99%

Vapor Intrusion Models for Petroleum and Chlorinated Volatile Organic Compounds: Opportunities for Future Improvements

Bekele

Naidu

Bowman³

et al. 2013

Vadose Zone Journal

View full text Add to dashboard Cite

The natural attenuation (NA) of volatile organic compounds (VOCs) is becoming recognized as a means of remediating contaminated sites and is generating widespread research interest. Recently, researchers incorporated NA into a vapor intrusion model (VIM) to more precisely predict the potential risk to humans and to more effectively screen contaminated sites. The NA of VOCs is a complex phenomenon that includes a range of biogeochemical reactions and physical processes. In this review, the various processes are discussed, including factors contributing to natural attenuation of VOCs in the unsaturated subsurface and their implications for site screening and risk assessment by a VIM. Vapor intrusion is the subject of active research focusing on a complex transport medium (subsurface soils) for which reliable and accurate mathematical models are required. The application of mathematical algorithms to simulate these complex processes often requires simplification and certain assumptions. Consequently, the simplifications and assumptions influence the model's predictive output. An overview of the theoretical basis and model algorithms of recently published models that account for the NA of volatile petroleum hydrocarbons in subsurface soils is provided. We also highlight the need to include the NA of chlorinated hydrocarbons in the VIM.

show abstract

“…Both the Redfield Rifle Scope Site (Redfield) and the Colorado Department of Transportation Material Testing Laboratory Site (CDOT MTL) are well-known vapor intrusion sites in Denver, Colorado (Folkes et al 2009;Johnson et al 2009). At both sites, historic waste management practices at industrial facilities resulted in the off-site contamination of shallow groundwater with a variety of chlorinated volatile organic compounds (VOCs).…”

Section: Introductionmentioning

confidence: 99%

Evidence for Increasing Indoor Sources of 1,2‐Dichloroethane Since 2004 at Two Colorado Residential Vapor Intrusion Sites

Kurtz¹,

Wolfe²,

Woodland³

et al. 2010

Groundwater Monitoring Rem

Self Cite

View full text Add to dashboard Cite

Groundwater contamination associated with two former industrial facilities in Denver, Colorado, has led to concerns about vapor intrusion into residences adjacent to the facilities. 1,1,1‐Trichloroethane (1,1,1‐TCA), 1,1‐dichloroethene (1,1‐DCE), and trichloroethene (TCE) are the main contaminants of concern in groundwater, with trace levels of 1,2‐dichloroethane (1,2‐DCA) present at one of the sites. Indoor air monitoring programs have been ongoing at these two sites since 1998 and recent results have suggested that background, indoor source, 1,2‐DCA has been increasing in the frequency of detection, and median and maximum concentration over the past several years. A lines of evidence evaluation was undertaken for both sites in order to document the predominance of indoor sources of 1,2‐DCA. Evidence utilized included spatial evaluation of 1,2‐DCA in indoor air; comparison of 1,2‐DCA concentrations in mitigated and unmitigated homes; a phone survey to evaluate the potential for smoking to contribute to indoor air 1,2‐DCA levels; evaluation of mitigation system effluent data; and an evaluation of volatile organic compound (VOC) ratios in groundwater and indoor air. The results of this evaluation indicated that smoking had no demonstrable influence on measured indoor air concentrations. In addition, it appears that consumer products have had a markedly increased influence on indoor air concentrations since 2005. Data from one of the industrial facilities at one of the sites also indicated that polyvinyl chloride (PVC) and vinyl composite floor adhesive used in a building remodel in 2005 apparently generated elevated levels of indoor 1,2‐DCA and vinyl chloride, which have been sustained up to the present time.

show abstract

Empirical Assessment of Ground Water–to‐Indoor Air Attenuation Factors for the CDOT‐MTL Denver Site

Cited by 12 publications

References 11 publications

Examining the Use of USEPA's Generic Attenuation Factor in Determining Groundwater Screening Levels for Vapor Intrusion

Examining the Use of USEPA's Generic Attenuation Factor in Determining Groundwater Screening Levels for Vapor Intrusion

Vapor Intrusion Models for Petroleum and Chlorinated Volatile Organic Compounds: Opportunities for Future Improvements

Evidence for Increasing Indoor Sources of 1,2‐Dichloroethane Since 2004 at Two Colorado Residential Vapor Intrusion Sites

Contact Info

Product

Resources

About