Microscale Carbon Monoxide Impact Assessment for the Atlantic Steel Development Project

Hagler Bailly Services, Inc., is under contract to the US Environmental Protection Agency toevaluate the environmental impacts of redeveloping the Atlantic Steel site in Midtown Atlanta.As part of the modeling of the development impacts, EPA required assistance in evaluatingwhether the proposed development would produce new CO hotspots in the surroundingneighborhood. To provide that support, the contractor assembled a microscale modeling teammade up of staff from the Georgia Institute of Technology who served as project subcontractors.Drs. Randall Guensler and Michael Rodgers led the research team and directed the research andmodeling tasks summarized in this document.The Atlantic Steel project is a major urban development located in downtown Atlanta. Freewayaccess to the area is proposed from I-75 between Howell Mill road and 14th Street. Because theproject will yield a significant increase in number of trips generated and attracted to the localarea, and vehicle miles of travel on arterial roads and freeways, it is necessary to undertake ananalysis of the local air quality impacts expected to result from the development. For federalagency approvals to be issued, the project must not create a violation of the ambient air qualitystandards for carbon monoxide. Figure 1 illustrates the proposed project location near theGeorgia Institute of Technology.The research team developed the modeling framework using a variety of off-the-shelf modelingtools. The MOBILE5a emission rate model and CALINE4 line source dispersion model servedas the analytical tools of choice for this project. A geographic information system (GIS) wasemployed to link standard regional travel demand model results with the line source analyses.PERL scripts and FORTRAN programming was employed to link corridor travel simulationmodel results with the line source analyses. Data input files were provided by Hagler BaillyServices, Inc., Moreland Altobelli, Inc., the Georgia Department of Transportation, AtlantaRegional Commission, and Georgia Institute of Technology. The GIS graphics for network andmodel documentation were developed and links and receptor sites were coded for input to theCALINE4 model. The team reviewed aggregate model outputs and developed appropriatevolumes and speeds for microscale analyses. The team also developed and documented allrequired meteorological parameters and emission rates for use in analyses.The research team developed new program code to feed the outputs of a variety of vehicleactivity and emission rate models into CALINE4 analyses. The new model code was non-invasive, in that the standard models were not modified. Instead, the team developed code thatwould allow standard models and output data files to be called and run for any desiredconditions. The new code allowed the modeling team to run analyses for hundreds of roadwaylinks and receptor sites, predicting worst-case pollutant concentrations throughout the projectregion. The model code predicts and displays the worst-case wind angle for each receptor in theregion. Standardized graphical output reports were prepared for receptors and links, and vectorsillustrate the wind direction for worst-case concentrations at receptors. The team also selectedadditional receptor sites for modeling based on their familiarity with the local region and theirprofessional judgment.