Modeling & Analytics

Dispersion modeling

RSG’s customized dispersion models simulate how air pollutant emissions from mobile and stationary sources are dispersed in the atmosphere and how they concentrate near adjacent activity centers, reflecting topography, land use, buildings, roads, weather, etc. We excel at integrating these models into other analyses to help our clients design and operate projects complying with air quality standards.
RSG often integrates air dispersion models with traffic activity models and mobile emissions models for transportation applications. Our extensive experience with traffic modeling from the regional to microsimulation levels enables us to integrate the appropriate level of traffic activity data into mobile emissions models such as EPA’s MOVES model for conducting a regional- or project-level conformity analysis, or for supporting air quality analysis for NEPA.
For conformity analyses, emission rates from MOVES are input into air dispersion models, such as AERMOD or CALQ3HC. These modeling techniques inform the planning and design process on the likely local air quality impacts of proposed transportation changes, such as a new connector road or a change in intersection control.
For stationary sources such as heat, power, or manufacturing plant stacks, we often integrate dispersion modeling withair permit applications, air toxics evaluations, accidental release safety studies, odor analyses, and risk assessments. Dispersion models, such as AERMOD are integrated with these analyses to inform project planning and design and provide regulatory assurance. Model results are typically used to determine stack height/location, emission control technology, manufacturing process specifications,and fuel specifications.