Models And Modeling
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The resources below provide information about conceptual site model development, for sites where PVI may be a concern.
- Abreu, Lilian, and Paul Johnson. 2005. Effect of Vapor Source-Building Separation and Building Construction on Soil Vapor Intrusion as Studied with a Three-Dimensional Numerical Model. Environmental Science and Technology 39:4550-4561.
A three-dimensional numerical model of the soil vapor-to-indoor air pathway is developed and used as a tool to estimate relationships between the vapor attenuation coefficient, the ratio of indoor air concentration to source vapor concentration, and vapor source-building lateral separation, vapor source depth, and building construction characteristics (depth of building foundation) for nondegrading chemicals.
- Abreu, Lilian, and Paul Johnson. 2006. Simulating the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into Buildings - Influence of Degradation Rate, Source Concentration, and Depth. Environmental Science and Technology 40:2304-2315.
Uses a three-dimensional multicomponent numerical model to study steady-state vapor intrusion scenarios involving aerobically biodegradable chemicals.
- Abreu, Lilian, Robert Ettinger, and Todd McAlary. 2009. Simulated Soil Vapor Intrusion Attenuation Factors Including Biodegradation for Petroleum Hydrocarbons (PDF). Ground Water Monitoring and Remediation 29:105-117. (13 pp, 567K)
Describes results from three-dimensional numerical model simulations of vapor intrusion for petroleum hydrocarbons to assess the influence of aerobic biodegradation on the attenuation factor for a variety of source concentrations and depths for residential buildings with basements and slab-on-grade construction.
- Bozkurt, Ozgur, Kelly Pennell, and Eric Suuberg. 2009. Simulation of the Vapor Intrusion Process for Nonhomogeneous Soils Using a Three-Dimensional Numerical Model (PDF). Ground Water Monitoring and Remediation 29:92-104. (13 pp, 1.0MB)
Presents model simulation results of vapor intrusion into structures built atop sites contaminated with volatile or semivolatile chemicals of concern. A three-dimensional finite element model was used to investigate the importance of factors that could influence vapor intrusion when the site is characterized by nonhomogeneous soils.
- DeVaull, George. 2007. Indoor Vapor Intrusion with Oxygen-Limited Biodegradation for a Subsurface Gasoline Source. Environmental Science and Technology 41:3241-3248.
Presents a mathematical model that simulates PVI and includes aerobic biodegradation.
- Hers, Ian, Reidar Zapf-Gilje, Dyfed Evans, and Loretta Li. 2002. Comparison, Validation, and Use of Models for Predicting Indoor Air Quality from Soil and Groundwater Contamination. Soil and Sediment Contamination 11:491-527.
Evaluates different soil vapor transport to indoor air screening models through a review of model characteristics and sensitivity, and through comparisons to measured conditions at field sites.
- Hers, Ian, Reidar Zapf-Gilje, Paul Johnson, and Loretta Li. 2003. Evaluation of the Johnson and Ettinger Model for Prediction of Indoor Air Quality. Ground Water Monitoring and Remediation 23:119-133.
A comprehensive evaluation of the Johnson and Ettinger (J&E) model through sensitivity analysis, comparisons of model-predicted to measured vapor intrusion for 11 petroleum hydrocarbon and chlorinated solvent sites, and a review of radon and flux chamber studies. The paper highlights the importance in using appropriate input parameters for the J&E model and discusses the regulatory implications associated with use of the J&E model to derive screening criteria.
- Johnson, Paul, and Robert Ettinger. 1991. Heuristic Model for Predicting the Intrusion Rate of Contaminant Vapors into Buildings. Environmental Science and Technology 25:1445-1452.
Presents a heuristic model of screening-levels calculations for predicting vapor intrusion rates and includes sample calculations for a range of parameter values to illustrate use of the model and the relative contributions of individual transport mechanisms.
- Johnson, Paul. 2005. Identification of Application-Specific Critical Inputs for the 1991 Johnson and Ettinger Vapor Intrusion Algorithm. Ground Water Monitoring and Remediation 25:63-78.
Outlines the relationships between model inputs and outputs so that users can identify critical inputs when applying the Johnson and Ettinger model.
- Olson, David and Richard Corsi. 2001. Characterizing Exposure to Chemicals from Soil Vapor Intrusion Using a Two-Compartment Model. Atmospheric Environment 35:4201-4209.
Discusses the use of a two-compartment model (one for the basement and one for the remainder of the house) to characterize subsurface transport on the indoor environment. A field study was completed to quantify parameters associated with the two-compartment model, such as soil gas intrusion rates and basement to ground floor air exchange rates. Results indicate that exposures are highly dependent on gas intrusion rates, basement ventilation rate, and fraction of time spent in the basement.
- Park, H. 1999. A Method For Assessing Soil Vapor Intrusion From Petroleum Release Sites: Multi-Phase/Multi-Fraction Partitioning (PDF). Global Nest 1:195-204. (10 pp, 268K)
A model and spreadsheet-based numeric approximation for computing risk-based soil cleanup levels for the indoor air exposure pathway at petroleum-contaminated sites.
- Parker, Jack. 2003. Modeling Volatile Chemical Transport, Biodecay, and Emission to Indoor Air (PDF). Ground Water Monitoring and Remediation 23:107-120. (14 pp, 1.3MB)
Presents a model for estimating vapor concentrations in buildings because of volatilization from soil contaminated by non-aqueous phase liquid (NAPL) or dissolved contaminants in groundwater. The model considers source depletion, diffusive-dispersive transport of the contaminants and of oxygen and oxygen-limited contaminant biodecay.
- Pennell , Kelly, Ozgur Bozkurt, and Eric Suuberg. April 2009. Development and Application of a Three-Dimensional Finite Element Vapor Intrusion Model Source. Journal of the Air and Waste Management Association 59:447-460.
A three-dimensional finite element model of soil vapor intrusion, including the overall modeling process and the stepwise approach.
- Provoost, Jeroen, Annelies Bosman, Lucas Reijnders, Jan Bronders, Kaatje Touchant, and Frank Swartjes. 2009. Vapour Intrusion from the Vadose Zone - Seven Algorithms Compared. Journal of Soils and Sediments 10:473-483.
Evaluates seven screening-level algorithms, predicting vapor intrusion into buildings as a result of vadose zone contamination, regarding the accuracy of their predictions and their usefulness for screening purpose. The algorithms with the highest accuracy for predicting the indoor air concentration were the Johnson-Ettinger model and Vlier–Humaan algorithms.
- Sanders, Paul and Nazmi Talimcioglu. 1997. Soil-to-Indoor Air Exposure Models for Volatile Organic Compounds: The Effect of Soil Moisture. Environmental Toxicology and Chemistry 16:2597-2604.
Discusses two finite-source models used to study the effect of soil moisture on indoor air concentrations and inhaled doses. Indoor air concentrations and inhaled doses for the model contaminant varied by up to seven orders of magnitude, depending on the soil moisture conditions and whether or not contaminant degradation was considered.
- Tillman, Fred and James Weaver. 2007. Parameter Sets for Upper and Lower Bounds on Soil-to-Indoor-Air Contaminant Attenuation Predicted by the Johnson and Ettinger Vapor Intrusion Model. Atmospheric Environment 41:5797-5806.
Used EPA-recommended ranges of parameter values for nine soil-type/source depth combinations to identify input parameter sets that correspond to best and worst case results of the Johnson and Ettinger model. The results established the existence of generic best and worst case parameter sets for maximum and minimum exposure for all soil types and depths investigated.
- Tillman, Fred and James Weaver. July 2006. Uncertainty from Synergistic Effects of Multiple Parameters in the Johnson and Ettinger (1991) Vapor Intrusion Model. Atmospheric Environment 40:4098-4112.
Presents results of multiple-parameter uncertainty analyses using the Johnson and Ettinger model to evaluate risk to humans from vapor intrusion.
- Yao, Yijun, Rui Shen, Kelly Pennell, and Eric Suuberg. March 2011. Comparison of the Johnson-Ettinger Vapor Intrusion Screening Model Predictions with Full Three-Dimensional Model Results. Environmental Science and Technology 45:2227-2235.
Compares predictions from a three-dimensional model of vapor intrusion, based upon finite element calculations of homogeneous soil scenarios, with the results of the Johnson-Ettinger model. Results suggest that there are conditions under which the model predictions might be reasonable but that there are also others in which the predictions are low as well as high.