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Petroleum Release Assessment and Impacts of Weather Extremes
Citation:
Weaver, Jim. Petroleum Release Assessment and Impacts of Weather Extremes. Oklahoma Governor’s Water Conference and Research Symposium, Norman, OK, October 11 - 12, 2016.
Impact/Purpose:
Contaminated ground water and vapor intrusion are two major exposure pathways of concern at petroleum release sites. EPA has recently developed a model for petroleum vapor intrusion, called PVIScreen, which incorporates variability and uncertainty in input parameters. This approach is necessary because vapor intrusion model parameters are either not commonly measured (e.g., residential air exchange rate, sub-slab soil moisture content, foundation crack characteristics) or not measureable on a site-specific basis (biodegradation rates). Consequently the model is driven by Monte Carlo analysis and the results given as probability of indoor air concentrations exceeding health screening levels. The model has been applied to leaking underground storage tank sites in Oklahoma. As conditions change at these sites, either wetter or dryer the prospects for vapor impacts may change. The primary weather-related factors influencing vapor intrusion are the soil moisture content and depth to water. An Assessment of these using PVIScreen and the Oklahoma cases will be presented. Shifting patterns of ground water flow occurring due to changing demand for ground water may also impact exposure to petroleum contaminants. Several examples, based on conditions at Oklahoma sites will be described.
Description:
Contaminated ground water and vapor intrusion are two major exposure pathways of concern at petroleum release sites. EPA has recently developed a model for petroleum vapor intrusion, called PVIScreen, which incorporates variability and uncertainty in input parameters. This approach is necessary because vapor intrusion model parameters are either not commonly measured (e.g., residential air exchange rate, sub-slab soil moisture content, foundation crack characteristics) or not measureable on a site-specific basis (biodegradation rates). Consequently the model is driven by Monte Carlo analysis and the results given as probability of indoor air concentrations exceeding health screening levels. The model has been applied to leaking underground storage tank sites in Oklahoma. As conditions change at these sites, either wetter or dryer the prospects for vapor impacts may change. The primary weather-related factors influencing vapor intrusion are the soil moisture content and depth to water. An Assessment of these using PVIScreen and the Oklahoma cases will be presented. Shifting patterns of ground water flow occurring due to changing demand for ground water may also impact exposure to petroleum contaminants. Several examples, based on conditions at Oklahoma sites will be described.