Development of a Screening Model for the Migration of Contaminated Soil Vapor Into the Indoor Air Environment PDF Download
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Author: Matthew Daniel Jordan
Publisher:
ISBN:
Category :
Languages : en
Pages : 164
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Book Description
The migration of contaminants from the subsurface into the indoor air environment, in a process described as soil vapor intrusion, is gaining attention as a potential pathway for exposure to contaminated soil and water. Indoor, outdoor and soil air samples were collected from forty homes in North Texas to investigate the attenuation of trichloroethylene (TCE) from contaminated groundwater into residential buildings. The mean and standard deviation of the soil and indoor air attenuation factors (ratio of indoor air concentration to soil vapor concentration) were 0.14 and 0.17, respectively. Five of the 40 values were greater than 0.1 which is the suggested upper-bound by the U.S. EPA (2002). Statistical tools were used to draw correlative relationships between contaminant groundwater, soil air and indoor air concentrations. The VolaSoil model described by Waitz et al. (1996), was modified for use as a screening tool for future investigations of indoor TCE concentration. Using measured soil vapor data, the model under predicted indoor air TCE concentrations likely due to heterogeneities in the unsaturated subsurface. Inputting groundwater TCE concentrations, the model was able to capture the contaminant migration processes and produce results consistent with measured indoor TCE concentrations. Therefore, the model described in this paper maybe appropriate to be use as a screening tool in future investigations in the contamination area.
Author: Matthew Daniel Jordan
Publisher:
ISBN:
Category :
Languages : en
Pages : 164
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Book Description
The migration of contaminants from the subsurface into the indoor air environment, in a process described as soil vapor intrusion, is gaining attention as a potential pathway for exposure to contaminated soil and water. Indoor, outdoor and soil air samples were collected from forty homes in North Texas to investigate the attenuation of trichloroethylene (TCE) from contaminated groundwater into residential buildings. The mean and standard deviation of the soil and indoor air attenuation factors (ratio of indoor air concentration to soil vapor concentration) were 0.14 and 0.17, respectively. Five of the 40 values were greater than 0.1 which is the suggested upper-bound by the U.S. EPA (2002). Statistical tools were used to draw correlative relationships between contaminant groundwater, soil air and indoor air concentrations. The VolaSoil model described by Waitz et al. (1996), was modified for use as a screening tool for future investigations of indoor TCE concentration. Using measured soil vapor data, the model under predicted indoor air TCE concentrations likely due to heterogeneities in the unsaturated subsurface. Inputting groundwater TCE concentrations, the model was able to capture the contaminant migration processes and produce results consistent with measured indoor TCE concentrations. Therefore, the model described in this paper maybe appropriate to be use as a screening tool in future investigations in the contamination area.
Author:
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 117
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Book Description
Vapor intrusion models were developed to predict indoor air concentrations from subsurface sources and then calculate an associated risk using toxicological data and exposure scenarios for the building occupants. Prior to the issuance of final guidance documents in 2015, the United States Environmental Protection Agency (USEPA) guidance on vapor intrusion was in draft form since November 2002. This delay between the draft version and the final guidelines resulted in the utilization of varying methodologies for assessing vapor intrusion by the regulated community and as well as the regulators at both state and local levels. The purpose of this study was to evaluate the accuracy of screening-level vapor intrusion models, using soil vapor samples collected from three sites with known or suspected contamination, and to compare the predicted indoor air results with measured indoor air results. The models evaluated were the County of San Diego Department of Environmental Health Vapor Risk 2000 Model, the Department of Toxic Substances Control (DTSC) version of the Johnson and Ettinger Model (J&E Model), and the USEPA, Office of Solid Waste and Emergency Response (OSWER), Vapor Intrusion Screening Level Calculator (VISLC). The results of this study found that the Vapor Risk 2000 Model more accurately predicts indoor air concentrations, followed by the J&E Model and VISLC. While the Vapor Risk 2000 Model more closely predicts the indoor air concentration, it does have a tendency to underpredict. Due to the underpredictions, there is more potential for false negatives (i.e., screening out sites that do have a potential for vapor intrusion. Similar to previous studies, this study found the Vapor Risk 2000 and J&E Models both over and under predict the indoor air concentrations. This may not necessarily be a reflection on the model’s prediction ability, but rather the complexity of vapor intrusion and the confounders of indoor air. Combined with additional lines of evidence (e.g., indoor air sampling), these screening-level vapor intrusion models can assist decision makers in screening in or out sites that are susceptible to vapor intrusion.
Author:
Publisher:
ISBN:
Category : Soil pollution
Languages : en
Pages : 182
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Book Description
Author: Jessica Marie Friscia
Publisher:
ISBN:
Category :
Languages : en
Pages : 127
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Book Description
Vapor intrusion is the migration of volatile organic compounds (VOCs) from a subsurface source into the indoor air of an overlying building. Vapor intrusion models, including the Johnson and Ettinger (J&E) model, can be used to predict the concentration of VOCs in the indoor air of a building based on a measured subsurface soil gas concentration or contaminant source concentrations, either in non-aqueous phase liquid (NAPL), groundwater, or soil. An analysis of two of the EPA-implemented J&E spreadsheet models, one that considers subsurface soil gas data and one that considers groundwater data, was conducted. The governing equations, assumptions, and limitations of these spreadsheet models were investigated. A value of information (Vol) worksheet was developed that can assist practitioners in deciding what additional data to collect as part of a remedial investigation. The Vol worksheet calculates how varying values of model input parameters affect the model-predicted indoor air carcinogenic risk. The worksheet then compares the user-defined target risk to the range of potential risk values for different combinations of varying parameters. The results of this analysis allow the user to determine which groups of parameters have the most impact on the model results. This information can assist the practitioner in deciding whether or not to collect additional data to reduce the uncertainty in the input parameters. The EPA J&E soil gas and groundwater spreadsheet models, as well as the Vol worksheet developed for each model, were applied to case study data for a trichloroethylene-impacted site in Rhode Island. The results of the J&E model and Vol worksheet analyses for this case study predicted incremental carcinogenic risk values for trichloroethylene (TCE) below the risk value calculated based on measured indoor air data. This comparison suggests the potential for other sources of TCE within the building. Groups of parameters were identified for each model that impacted the model-predicted carcinogenic risk. The development of a cost-benefit analysis, which would be used to quantify the value of obtaining additional data for these critical parameters, is recommended for future research.
Author: Yijun Yao
Publisher: Springer
ISBN: 9789811927027
Category : Science
Languages : en
Pages : 0
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Book Description
This book introduces key concepts in modeling and risk assessments of vapor intrusion, a process by which the subsurface volatile contaminants migrate into the building of concern. Soil vapor intrusion is the major exposure pathway for building occupants to chemicals from the subsurface, and its risk assessments determine the criteria of volatile contaminants in soil/groundwater in brownfield redevelopment. The chapters feature the recent advances in vapor intrusion studies and practices, including analytical and numerical modeling of vapor intrusion, statistical findings of United States Environmental Protection Agency’s Vapor Intrusion Database and Petroleum Vapor Intrusion Databases, the challenges of preferential pathways, and the application of building pressure cycling methods, and field practices of vapor intrusion risk assessments at developed contaminated sites and in brownfield redevelopment. This volume also summarizes the advantages and limits of current applications in vapor intrusion risk assessment, laying the groundwork for future research of better understanding in risk characterization of soil vapor intrusion using models. Written by experts in this field, Vapor Intrusion Simulations and Risk Assessments will serve as an invaluable reference for researchers, regulators, and practitioners, who are interested in perceiving the basic knowledge and current advances in risk assessments of soil vapor intrusion.
Author:
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages : 40
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Book Description
Author: United States. Congress. House. Committee on Appropriations. Subcommittee on Interior, Environment, and Related Agencies
Publisher:
ISBN:
Category : United States
Languages : en
Pages : 1198
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Book Description
Author:
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 70
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Book Description
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 782
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Book Description
Author: Jeff Polubinski
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
For decades, scientists have propounded on the risks of vapor intrusion, the process by which contaminants present in soil and groundwater migrate, via volatilization, into buildings and affect indoor air quality. After years of deliberation, the United States Environmental Protection Agency (USEPA) has now added a vapor intrusion component to the Hazard Ranking System (HRS). The USEPA uses the HRS to evaluate whether a site warrants inclusion on the agency's National Priorities List (NPL) for Superfund sites. While the inclusion of vapor intrusion on the HRS is a positive, albeit overdue, development in Superfund law, how USEPA structures and implements the vapor intrusion component into the existing HRS will determine whether this new enhancement will actually prove to be protective of human health. First, this note will examine the concept of vapor intrusion. Included in this discussion will be a description of the contaminants at play, how vapors enter buildings, where vapor intrusion sites are located, what the human health risks are and, lastly what is done to mitigate the risks that vapor intrusion presents. The note will then discuss the importance that vapor intrusion plays in the Brownfields, Superfund and the LEED-certified building discussion and why vapor intrusion is often identified as an environmental justice issue. Next, the note will discuss many of the difficulties facing vapor intrusion regulation and the roadblocks that may have inhibited the promulgation of federal regulation earlier. I will then describe the different ways states have regulated vapor intrusion by assessing two enforcement mechanisms used by states in regulating sites where vapor intrusion may be an issue. First, I will evaluate how states initially assess vapor intrusion versus how states assess other more regulated exposure pathways (such as ingestion of contaminated drinking water). If there is some sort of ranking or prioritization of sites, what weight, if any, is given to sites where vapor intrusion is an issue? Secondly, I will look at what steps states take, or require potentially responsible parties or responsible parties to take, when vapor intrusion has been identified. Lastly, based on components of state regulation, I will propose a regulatory framework for addressing vapor intrusion.
