Document QXdVQEmE50d44KLd534K88156

AR226-2654 44 AR226-2654 ISC Modeling Methodology and Results Introduction This report summarizes dispersion modeling that was completed for the DuPont Washington Works facility to demonstrate that the emission limits included in Permit Application 2365D for the PFA(Cl-P) operation complies with the C-8 assessment oftoxicity (CAT) recommended airborne screening level of 1.0 ug/m3 at the property line fence. In 2003, the fenceline along the Ohio River was modified for site security purposes. A Security Vulnerability Assessment was conducted for the Washington Works facility in 2002. The assessment concluded that the fenceline along the riverbank needed to be relocated as a countermeasure to any adversary gaining access to the site. The current modeling analysis includes this new fenceline. Emission Source Information Table 1 shows the stack parameters used in the model as well as the locations and emission rates for each emission point. The emission points impacted by these changes are C1FSE and C1FKE. C1FKE disappears, having been routed into C1FSE and upstream of the Deep Bed Scrubber (DBS) to reduce its emissions. Also, initial testing indicates the permitted overall efficiency of 95% can be raised to 96%, reducing the emissions from C1FSE. Modeling Methodology Dispersion modeling was performed using EPA's Industrial Source Complex 3 Model (ISC3), version 02035. All modeling was done in accordance with the procedures in EPA's Guideline on Air Quality Models (40 CFR Part 51, Appendix W). The EPA regulatory default options and rural dispersion coefficients were selected in the model. The APFO emission sources were evaluated for downwash effects from surrounding buildings. EPA's Building Profile and Input Program (BPIP) was used to provide wind direction specific building parameters. All buildings on the site were evaluated to determine if they could potentially impact the stack by causing building downwash effects. Plot plans showing the location of buildings included in the model are shown in Figures 1 and 2. (The buildings included in the model are identical to the list submitted under Consent Order GWR-2001-019). A 100-meter grid extending out 4,000 meters from the source was used. In addition, discrete receptors with 100-meter spacing were placed on the plant property line. Terrain elevations were imported from electronic files obtained from the U.S. Geological Survey using the "highest" method to assign an elevation to each receptor. One year ofon-site meteorological data (1996) was analyzed. Concurrent upper air data from Wilmington, OH was used to calculate twice-daily mixing depths. Missing data and measured C:\c8\permits\2004 PFA(Cl-P) Pennitdoc wind speeds of less than 1 m/s were treated consistent with the recommendations made in EPA's On-site Meteorological Program Guidance for Regulatory Modeling. An anemometer height of 10 meters was used for the modeling. Modeling Results An averaging time of one year was used to determine the annual average ground level concentrations over the entire receptor grid. A contour plot of these concentrations is shown in Figure 3. The maximum annual average ground-level concentration predicted by the model was 0.265 |lg/m3. This concentration occurred at a receptor located on the plant fenceline north of the plant. Electronic Files This report and the following electronic files were transmitted by email to Chris Sergent and Dave Roberts at WVDAQ on November 9, 2004: ISC Input file ISC Output file BPIP Input file BPIP Output file Meteorological Data file pfa(cl -p)_2004.dat pfa(cl -p)_2004.1st pfa(cl -p)_2004.bpi pfa(c 1-p)_2004.bpo pkbiln96.asc C:\c8\permits\2004 PFA(Cl-P) Permit.doc 2 Permit Vent ID T61ZCE T61XE T61YE T5HGE T5HIE C2DTE C1FSE T7IME R022EEF6 (Research) R022EEF86 (Research) R022EEF87 (Research) R022EEF89 (Research) Table 1 Stack Parameters Stack Stack Stack Stack Stack Modeling Vent ID 699 697 694 658 652 231 274 662 Zone 17 UTM-E 442098 442128 442101 441928 441926 441941 441790 442025 UTM-N 4346843 4346829 4346815 4346757 4346758 4346758 4346744 4346847 Diameter ft 4 2.25 1.67 1.5 0.88 1.00 0.69 1.33 Height ft 170 45 45 63 64 100 115 150 Flow ACFM 12,000 2,000 344 6,478 4,031 1,200 667 1788 Velocity ft/sec 15.9 8.4 2.6 61.1 111.7 25.5 29.4 21.4 Temp F 124 176 112 142 139 53 min 41 min 86 Permit Annual C-8 Emissions Ib/yr 3,258 3 3 94 71 2,753 1,327 0.0010 EEF6 442086 4346624 2.5 EEF86 442069 4346627 2 EEF87 442058 4346634 2 EEF89 442063 4346635 2 47 8836 49 7540 49 1885 49 3770 80 12 80 0.3 80 3 80 0.6 C:\c8\permits\2004 PFA(Cl-P) Permit.doc 4346900-^ 434680(H 4346700-^ 4346600-^ 4346SOO-H 441600 441700 441800 441900 442000 Figure I - Building Plot Plan 442100 C:\c8\permits\2004 PFA(Cl-P) Pennit.doc 4346850-- 4346800- 4346750- 4346700 441850 441900 441950 442000 442050 C:\c8\permits\2004 PFA(Cl-P) Permit.doc Figure 2 Building 162/163 Detail C:\c8\permils\2004 PFA(CI-P) Permit.doc ^^Ws-fcll Figure 3 Predicted Annual Average Concentrations (jig/in3)