Dispersion Modeling – Using as a Planning and Diagnostic Tool

摘要

The U.S. Environmental Protection Agency – Environmental Response Team (U.S.EPAERT) was established in October 1978 to provide technical assistance to On-Scene Coordinators (OSCs), Regional Response Teams (RRTs), and U.S.EPA Offices, for oil spills, hazardous waste activities and accidental chemical release situations. Many of the responses have involved air dispersion modeling to determine potential exposures to hazardous air pollutants (HAPs). Supporting the ERT is the Response Engineering and Analytical Contract (REAC), which provides technical support and expertise, including air dispersion modeling. This paper presents three actual case studies in which air dispersion modeling has been used as a diagnostic tool to identify areas that may have been impacted from an air release that occurred at a previous time. The paper also identifies where dispersion modeling has been used to identify sources of HAP emissions based upon air sampling and monitoring and local meteorology. In addition the paper also discusses using dispersion modeling in conjunction with a variety of sampling and monitoring techniques, including a Trace Atmospheric Gas Analyzer (TAGA) system and an Open Path Fourier Transform Infrared (FTIR) system, to estimate emission rates from various types of sources of HAP emissions. This paper describes the dispersion modeling methodologies used and their capability for providing useful information in the development of strategies for HAP sampling. This includes identifying particular HAP emission sources, determining the most probable impact areas from HAP sources and estimating emission rates from various types of sources.