Document v1pLzjka2Xp60D6bXM5aGxjvE

AR226-2650 RECYCLED O AR226-2650 ISC Modeling Methodology and Results Introduction This report summarizes dispersion modeling that was completed in support of interim updates to R13 permits 1953B and 2365C at the DuPont Washington Works site. 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 one emission point (276) has been added. This emission point had been erroneously omitted from the previous modeling. 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 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 o f 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's On-site Meteorological Program Guidance for Regulatory Modeling. An anemometer height of 10 meters was used for the modeling. C:\c8\permits\2003 Permit Modeling Results.doc r 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 0.848 ig/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 Arrington at WVDAQ on April 30, 2004: ISC Input file ISC Output file BPIP Input file BPIP Output file Meteorological Data file permit_2003 .dat permit_2003.1st permit_2003.bpi permit_2Q03 .bpo pkbiln96.asc 2 r P erm it V e n t ID T6IZC E T 6 IX E T 6 IY E T5HGE T5H IE C2DTE C2DW E C2EHE C1FSE C1FKE C3HP Table 1 Stack Parameters Reg 29 Reg 29 Zone 17 U n it ID TIV, E&F TIV T IF THG THI CDT CDW CEH CFS CFK CHP V e n t ID 699 697 694 658 652 231 232 242 274 268 276 UTM -E 442098 442128 442101 441928 441926 441953 441952 441945 441790 441774 441842 UTM -N 4346843 4346829 4346815 4346757 4346758 4346766 4346776 4346746 4346744 4346753 4346772 S ta c k D iam eter ft 4 2 .2 5 1.67 1.5 0 .8 8 0 .6 7 0 .6 7 . 0.5 0 .6 5 0.27 1.5 S ta c k H eight ft 170 45 45 63 64 92 99 114.5 110 7 2 .5 75 S ta c k S ta c k S ta c k F low V elocity T em p ACFM 1 2 ,0 0 0 2 ,0 0 0 344 6 ,4 7 8 4,031 510 710 1,048 400 100 5 ,0 0 0 ft/s e c 15.9 8.4 2.6 61.1 111.7 2 4 .4 33.9 89.0 20.4 28.7 47.2 F 124 176 112 142 139 148 128 117 149 110 amb 2003 P erm it Annual C -8 E m issions Ib/yr 3 ,2 5 8 3 3 94 71 1,562 1,562 2 ,2 3 2 2 ,5 7 5 300 0 .1 6 2003 P erm it Annual C -8 E m issions Ib /h r 0 .3 7 1 9 0 .0 0 0 3 0 .0 0 0 3 0 .0 1 0 7 0.0081 0 .1 7 8 3 0 .1 7 8 3 0 .2 5 4 8 0 .2 9 3 9 0 .0 3 4 2 0 .0 0 0 0 1 8 R022EEF6 R022EEF86 R022EEF87 R022EEF89 R e se a rch R esearch R esearch R esearch 442086 442069 442058 442063 4346624 4346627 4346634 4346635 2.5 2 2 2 47 8836 49 7540 49 1885 49 3770 E st. A c tu a l Ib/yr 80 12 80 0.3 80 3 80 0.6 0 .0 0 0 4 5 0 .0 0 0 4 5 0 .0 0 0 4 5 0 .0 0 0 4 5 Sv 3 4 5 y f e . s" 1: "M '; # f . m , ^ !:|: * / ............ *I * -... S YfK&M ! 1^, i 7 Q- I Figure 3 Pr^rtictprf A n n u al A v p raap rn n p p n trn tin n s illo /m ^ 6