Document Kz7n9np0MXLzVM8GzX10D8K8N

MScoodpeeliannad Cost of Air Dispersion Cathie Barton DuPont 03/10/03 AR226- Overview of the Scope Can hire contractor or use inhouse modeling resources GaDthaetraing Modeling InotefrRpreestualttison Ycoriutircianlphuetreis 03/10/03 Data Gathering Meteorological Data * Terrain elevation maps Stack Parameters - Location (coordinates) Minofdoegrlemeytrsaotttuyihopinsicfaolrly - Height - Temperature - Stack gas vertical velocity - Diameter - Emission rates for each compound Plot Plan - Exact locations of all sources - Property line - Building locations and heights EID 719401 03/10/03 Standard Model and Methodology EPA's preferred model: Industrial Source Complex Short Term 3 (ISCST3) Model Procedures detailed in EPA's Guideline on Air Quality Models (40 CFR 51 Appendix W) http://www.epa.gov/scram001/guidance/gui de/appw_01.pdf M H 03/ 10/03 Modeling Output Model will calculate hourly concentrations in ug/m3 across a study area (5 km x 5 km for example) Model will average those concentrations over a designated time period (24 hour, monthly, yearly) Concentration contours showed extent of different ug/m3 Also shows numerical values (top 10 in the study area and locations) 03/ 10/03 Technicolor Example of Output WcGnO EID 719404 r_ Interpretation of Results Compare maximum averaged concentration to appropriate "threshold" value - Maximum annual average would be compared to a chronic toxicity value - Maximum hourly average would be compared to an acute toxicity value P O Oo wcn 03/10/03 to EX D 719405 Cost and Timing Expect about 50 man-hours (_10 hours) Costs - Outside modeler charges approximately $150/hr - Meteorological data could be up to $1,000' - Estimate around $8,500 for an average job. o o owcn 03/10/03 o EID 719406