Document zz9m0Nwazyap9MqxKBg2XZM2R

HECYCLEO 05 AR226-2656 AR226-2656 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 the form R13 permits (815E, 1353B, 1953B, and 2365C) comply with the C-8 assessment o f toxicity (CAT) recommended airborne screening level of 1.0 ug/m3 at the property line fence. Compared to the modeling report submitted in October, 2003, this report incorporates several revisions to stack parameters that were the result o f stack testing, and the refinement o f UTM coordinates. 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. As a result, modeling needed to be redone in order to correctly represent this new fenceline in the modeling analysis. 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. Note that two emission points from previous modeling (242 and 232) have been removed from the model and emission point 231 has been relocated. Modeling Methodology Dispersion and deposition 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 o f 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. C:\c8\permits\2004 Permit Amendments New Fenceline.doc One year of on-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 wind speeds o f less than 1 m/s were treated consistent with the recommendations made in EPA' On-site Meteorological Program Guidance for Regulatory Modeling. An anemometer height of 10 meters was used for the modeling. Modeling Results An averaging time o f 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 0.299 |ig/m3. This concentration occurred at a receptor located on the new plant fenceline north of the plant. Electronic Files This report and the following electronic files were transmitted by email to Chris Arrington at WVDAQ on May XX, 2004: ISC Input file ISC Output file BPIP Input file BPIP Output file Meteorological Data file new_permit_2004_nfl.dat new_permit_2004_nfl.lst new_permit_2004_nfl.bpi new_permit_2004_nfl.bpo pkbiln96.asc C:\c8\permits\2004 Permit Amendments New Fenceline.doc 2 P erm it Vent ID T6IZCE T6IXE T6IYE T5HGE T5HIE C2DTE C1FSE C1FKE C3HP Table 1 Stack Parameters Stack Stack Stack Stack Stack Reg 29 Reg 29 Zone 17 Diameter Height Flow Velocity Temp Unit ID Vent UTM-E UTM-N ID TIV, E&F 699 442098 4346843 TIV 697 442128 4346829 TIF 694 442101 4346815 THG 658 441928 4346757 THI 652 441926 4346758 CDT 231 441941 4346758 CFS 274 441790 4346744 CFK 268 441774 4346753 CHP 276 441842 4346772 ft 4 2.25 1.67 1.5 0.88 1.00 0.65 0.27 1.5 ft ACFM ft/sec F 170 12,000 15.9 124 45 2,000 8.4 176 45 344 2.6 112 63 6,478 61.1 142 64 4,031 111.7 139 100 1,200 25.5 53 min 110 667 33.5 41 min 72.5 100 28.7 110 75 5,000 47.2 amb P erm it Annual C-8 E m ission s Ib/yr 3,258 3 3 94 71 2,753 1,327 300 0.16 P erm it Annual C-8 E m is sio n s Ib/hr 0.371918 0.000342 0.000342 0.010742 0.008059 0.314 0.15148 0.034247 0.000018 R022EEF6 (Research) R022EEF86 (Research) R022EEF87 (Research) R022EEF89 (Research) 442086 442069 442058 442063 4346624 4346627 4346634 4346635 2.5 2 2 2 47 8836 49 7540 49 1885 49 3770 80 12 80 0.3 80 3 80 0.6 0.00045 0.00045 0.00045 0.00045 C:\c8\permils\2004 Permit Amendments New Fenceline.doc 3 C:\c8\pennits\2004 Permit Amendments New Fenceline.doc 4 C:\c8\pennits\2004 Permit Amendments New Fenceline.doc Figure 2 Building 162/163 Detail 5 L jK ^roxC T '--i ~: ~k'tf 'T-L Duau i- A! ! j ^ t o l U 1'-(' : fl L W: cu ! 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