Power Plants and Neighboring Communities Mapping Tool Summary
The Power Plants and Neighboring Communities Mapping Tool has four views to identify communities that may be affected by power plant emissions.
- Uniform Buffers View,
- Plant-Specific Buffers View,
- Long-Range Downwind Areas View, and
- Upwind Plants view.
All views present socioeconomic data for the communities that are potentially affected by power plant emissions. The different views are explained below.
Uniform Buffers View
Presents socioeconomic characteristics for the areas within three miles of fossil fuel power plants.
Plant-Specific Buffers View
Presents socioeconomic characteristics for the areas that include communities more likely to be exposed to higher levels of emissions from fossil fuel power plants.
EPA used AERMOD dispersion modeling to determine two facility-specific screening distances to identify potentially-impacted census block groups within close proximity to a source (less than 50 km): a “maximum concentration radius” and an “intermediate concentration radius.”
The Power Plants and Neighboring Communities Mapping Tool displays information within a plant-specific buffer defined as the maximum concentration radius. A unique radius was determined for each power plant by averaging the distances to the ten highest modeled concentrations around a source. Defining a radius based on the ten highest concentrationsincludes the location of the absolute maximum concentration in the modeling domain as well as also additional areas of elevated concentration located at a variety of distances. Although important in proximity screening, this area it is not inclusive of all communities that may be impacted by a source.
Long-Range Downwind Areas View
Summarizes socioeconomic characteristics for many communities located downwind from fossil fuel power plants.
This methodology identifies census block groups located farther downwind that may also be impacted by a specific power plant. This long-range downwind approach is based on HYSPLIT trajectory modeling, which provides potential paths for pollutants as they are transported through the atmosphere. Associating these trajectories with intersected census block groups enables the identification of census block groups that are potentially impacted by pollutants from each power plant.
Note that the area displayed on the map is an approximation of areas potentially downwind of each power plant. For simplicity, and to account for limitations in the modeling methodology, the boundaries of the downwind areas were smoothed and simplified, and all interior areas included.
This screening-level approach identifies many of the census block groups that may be impacted by air pollution from each power plant for the period analyzed. This approach does not consider the magnitude of that impact, the atmospheric residence time, chemical dispersion, or atmospheric deposition of the pollutant.
Upwind Plants View
Identifies fossil fuel power plants that are located upwind of a selected location.