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APPLICATION OF EXAMS AS THE SURFACE WATER MODULE IN THE HWIR MULTIMEDIA RISK ASSESSMENT SYSTEM
Citation:
Ambrose Jr., R B. AND L A. Burns. APPLICATION OF EXAMS AS THE SURFACE WATER MODULE IN THE HWIR MULTIMEDIA RISK ASSESSMENT SYSTEM. Presented at 20th Annual Society of Environmental Toxicology and Chemistry Meeting, Philadelphia, PA, November 14-18, 1999.
Description:
Multimedia, multipathway risk assessment software has been developed for implementing the Hazardous Waste Identification Rule (HWIR). This regulation is intended to determine whether a waste should be considered hazardous, and confined to Subtitle D facilities, or safely released to Subtitle C disposal. To make this determination for a chemical, a set of multimedia simulations were conducted for 42 chemicals on a representative sample of 201 sites around the country. The Exposure Analysis Modeling System (Exams) was chosen for the surface water module in FRAMES-HWIR. Exams combines chemical loadings, transport, and transformation into a set of differential equations using the law of conservation of mass as an accounting principle. Exams represents water body networks using a series of water column and sediment compartments and a series of physical, chemical, and biological process equations. Exams is linked to FRAMES-HWIR by the ExamsIO module. For each realization in a Monte-Carlo simulation, ExamsIO reads databases describing the site layout, the chemical properties, and the flows and loadings generated by the source, air, land surface, and groundwater modules. This information is used to build an Exams network and an Exams batch input file. ExamsIO then executes Exams and processes its results files for use by other modules in FRAMES-HWIR. Software verification is an important aspect of a development project such as HWIR. Exams and ExamsIO were subjected to several tests, including comparisons with simplified analytical solutions to verify computational setup and accuracy. These efforts have resulted in an accurate, robust surface water module that successfully simulates a wide range of chemicals in a diverse range of water body networks.