Document 9JJ6qEeZYgey4qn2Bz1o38Zmp

RECYCLED W CO AR226-2649 AR226-2649 ISC Modeling Methodology and Results Emission Source Information The ISC3 model was used to calculate ambient ground-level air concentrations and deposition rates for year 2000 actual C8 emissions from the Washington Works site. Table 1 shows the stack parameters used in the model for each emission point. Table 2 shows the emission rates used. The stack parameters and emission rates used are those that were submitted pursuant to Consent Order GWR-2001-019. In addition, two additional emission points have been added to the model beyond what was submitted pursuant to the Consent Order. Since the C8 emissions are partitioned between the vapor and particle phases, deposition runs were completed by modeling each phase separately. (Modeling runs to determine ground-level concentrations were based on the total emissions.) Deposition modeling requires particle size distribution information and scavenging coefficients for each phase o f emissions (vapor and particle). The size distribution information used in the modeling for the particle phase was obtained from testing at the Washington Works site. The scavenging coefficients used for the particle phase were obtained from Figure 1-11 o f the EPA ISC3 User's Guide. The vapor phase scavenging coefficients used were based on calculations by DuPont which were submitted under the Consent Order. This data shows the calculated vapor scavenging coefficient based on rain intensity. Since only one value o f the scavenging coefficient can be entered into the ISC3 model, the largest scavenging coefficient was chosen to ensure that the mode1predictions were conservative. Table 3 shows the gas and particle data used in the model and, additionally, shows the basis for the vapor scavenging coefficient used in the model. Modeling Methodology Dispersion and deposition modeling was' performed using the Industrial Source Complex 3 Model (ISC3), version 00101, provided by Lakes Environmental. 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 used in the model. The C8 emission sources were evaluated for downwash effects from surrounding buildings. The Lakes Environmental BPIP View model 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. A plot plan showing the location o f buildings included in the model is shown in Figure 1. (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. 6/ 7/02 An additional receptor grid was used to determine deposition to the watershed for the Little Hocking Water Association well field. A USGS topographical map was used to identify the general area of the watershed (Figure 2), and a receptor grid with 100 meter spacing was placed within this watershed (Figure 3). One year of on-site meteorological data (1996) was analyzed. The data was processed by Trinity consultants, using Wilmington, Ohio for the upper air data. The precipitation data used is from the Parkersburg, West Virginia airport. Missing data and measured wind speeds of less than 1 rn/s were treated consistent with the recommendations made in EPA's On-site Meteorological Program Guidance for Regulatory Modeling. An anemometer height o f 10 meters was used for the modeling. Modeling Results An averaging time o f one year was used to determine the annual average vapor concentrations and annual deposition rates over the entire receptor grid. A contour plot o f the annual average vapor concentrations is shown in Figure 4. Contour plots of the total deposition rates for the particle and vapor phases are shown in Figures 5 and 6. The maximum off-site values predicted by the model were: Maximum Annual Average Ground-Level Concentration = 2.675 ig/m3 Particle Phase: Maximum Dry Deposition Rate = 0.1347 g/m2/yr Maximum Wet Deposition Rate = 0.0456 g/m2/yr Maximum Total Deposition Rate = 0.1803 g/m2/yr Vapor Phase: Maximum Wet Deposition Rate = 0.0085 g/m2/yr The maximum ground-level concentration and all o f the maximum deposition rates were . predicted to occur at the same receptor (442135.47E, 4346899N), which is located on the plant fenceline north of the plant. The maximum annual ground-level concentration predicted to occur in areas where people may reside in the community is approximately 0.8 }lg/m3. Additionally, a smaller receptor grid was used to determine the annual deposition rate to the Little Hocking well watershed. The model was run to calculate vapor and particle phase deposition rates for each receptor, which rates were then imported into a spreadsheet. An average deposition rate was calculated for all of the receptors and multiplied by the receptor grid area (2.57 km2) to get a total deposition per year over the entire watershed. The deposition amounts calculated were: Particle Phase: . Vapor Phase: Total Dry Deposition = 6,732 g/yr (14.8 lb/yr) Total Wet Deposition = 12,608 g/yr (27.8 lb/yr) Total Deposition = 19,340 g/yr (42.6 lb/yr) Total Wet Deposition = 1,644 g/yr (3.6 lb/yr) 2 6/ 7/02 Table 1 Stack Parameters Pcrmil Number Permit Vent ID Reg 29 Zone 17 Vent ID UTM-K l ITM-N Stuck Height (ft) Slack Stack Stack Stack Diameter rlow Velocity 1emperaturc (ft) (II1. min) (ft's) (F) 1823A 815D 815D 1353A Pre-Existing 614A 614A 781 1953 2365A 2365A 2365A Semiworks Application Semiworks Application Semiworks Application Semiworks Application T7IME T6IFCE T6IZCE 164-5E 164-2E 163-E-26 163-E-l 1 163-E-33 242 C1FSE C1FKE Cl CAE R022EEF6 R022EEF86 R022EEF87 R022EEF89 662 644 699 652 658 231 232 216 242 274 268 205 442025 442084 442091 441920 441923 441952 441953 441960 441954 441787 441774 442310 442086 442069 442058 442063 4346847 4346835 4346836 4346767 4346756 4346776 4346766 4346788 4346741 4346744 4346753 4346800 4346624 4346627 4346634 4346635 150 59 63 70 68 93 81 60 114.5 110 72.5 6.66 47 49 49 49 1.33 1.5 18-1 ft 1.96 1.63 0.67 0.67 1.3 0.5 0.69 0.27 0.5 2.5 2.0 2.0 2.0 3,349 18,000 18000a 9,800 2,800 500 600 2,750 1,250 1,000 100 1,000 8836 7540 1885 3770 40.2 169.8 21.2b 54.1 22.4 23.6 28.4 34.5 106.1 44.6 29.1 84.9 30.0 40.0 10.0 20.0 172 111 111 200 300 130 130 158 200 255 110 70 80 80 80 80 aVent ID T61ZCE consists of 18 one-foot diameter vents. The flow rate given is the total for all 18 vents. bThe velocity listed is the velocity calculated for one individual vent. 3 Table 2 Emission Information Permit Vent 1D Rcg 29 \'ent II) Particle Mass fraction T7IME T6IFCE T6IZCE 164-5E 164-2E 163-E-26 163-E-l1 163-E-33 242 C1FSE C1FKE C1CAE R022EEF6 R022EEF86 R022EEF87 R022EEF89 662 644 699 652 658 231 232 216 242 274 268 205 0 0.54 0.9 0.9 0.9 0.11 0.09 0 0.9 0.03 1 1 1 1 1 1 ,Vapor Mass Fraction 1 0.46 0.1 0.1 ' 0.1 0.89 0.91 1 0.1 0.97 0 0 0 0 0 0 Year 2000 Actual ('8 Finissions flhjr) Year 2000 2000 Actual Actual Particle Phase C8 Emissions Emission Rate llI ilM wmHUmm 2000 Actual Vapor Phase Emission Rate (g/s) 0 13,977 0 33 79 3,541 4,680 0 3,510 5,414 107 0 12 0.3 3 0.6 0 0.2010 0 0.0005 0.0011 0.0509 0.0673 0 0.0505 0.0779 0.0015 0 1.73E-04 4.32E-06 4.32E-05 8.63E-06 0 0.1086 0 4.27E-04 0.00102 0.00560 0.00606 0 0.0454 0.00234 0.0015 0 1.73E-04 4.32E-06 4.32E-05 8.63E-06 0 0.0925 0 4.75E-05 1.14E-04 0.0453 0.0613 0 0.00505 0.0755 0 0 0 0 0 0 6/ 7/02 Table 3 Gas & Particle Data Particle Phase: Particle Diameter (microns) 0.2 0.4 0.75 2.0 4.0 Mass Fraction 0.538 0.267 0.035 0.127 0.033 Particle Density (g/cm3) 2.2 2.2 2.2 2.2 2.2 Scavengini Coefficients Liquid Frozen Precipitation Precipitation (s'Vmm-h"1) (s'Vmm-h'1) 1.2x104 4x10^ 5x10"S 1.67x1 O'5 4x1 O^ 1.33x10^ 1.3x10"4 4.33xl0"5 2.8x1 O'4 9.33xl0'5 Vapor Phase: Liquid Scavenging Coefficient (s'Vmm-h'1) = 6.4x1 O'6 Frozen Scavenging Coefficient (s'Vmm-h'1) = 6.4xl0'6 Calculations of Vapor Scavenging Coefficient: - vapor scavenging coefficients are presented in the consent order submittal as a list of values for different rainfall intensities - the vapor scavenging coefficient that is entered into the ISC model is in units of s'Vmm-h"1, therefore the scavenging coefficients shown in the consent order must be adjusted to the proper units and then divided by the rainfall intensity * - to ensure that model predictions would be conservative, the scavenging coefficient based on a 1 mm/hr rain intensity was used, as this gives the largest value for input into the model 2.31 lxl (T2-- x --^ - x -- = 6.4x10"6---- = 6.4x1O'6-- -- T hr 3600s 1mm s mm mm hr 5 6/ 7/02 Figure 1 - Building Plot Plan 7 Figure 2 8 6/ 7/02 4348500--i 4348000 43475004347000 6/ 7/02 ++++++++++++++++++++++ ++ ++ + ++ + + + + + ++ ++ + ++ ++ + + + 4- + + + + + + + + + + + + + + + + + + + + + 4- + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + .+ + + + + + + + + 4- 4- + + + + + + + + + + + + + + + + + 4- + + 4- 4- + + + + + + + + + + + + + + + + + + + + + + + + + + 4- 4+ 4- + + + + + + + + + + + + + + + + + + + + + + + + + + 4- + + Hr + + + + + + + + + 4- + + + + + + 4+ + + + + + + + + + + + + + + + + + 4- + 4- 4+ + + 4- + + + + + + + + + + + + + + 4- 4- 4- 4- 4346500- 4346000-----441000 441500 442000 442500 443000 ~ -- i-------------- 443500 444000 Figure 3 Little Hocking Well Watershed Receptors Modeled 444500 445000 9 C8 2000 Actual Emissions Annual Average Air Concentrations (ug/m3) 6/ 7/02 10 PROJECT NAME : C8 2000 Actual Emissions - Particulate Phase Total Deposition (g/m2/yr) 6/ 7/02 MODELING OPTIONS : CONC, DEPOS, DDEP, WDEP, RURAL, ELEV, DFAULT, DRYDPL, WETDPL RECEPTORS : 3529 OUTPUT TYPE : DEPOS CO q o MAX : 0.18029 UNITS : g/m**2 ISC-AERMOD View by Lakes Environmental Software DATE : 6/6/2002 0 PROJECf/PLOT NO. : 1 km C:\ISCVIEW3\WASHINGTON WORKS\ACTOOPR.!S\ANOOGALL.PLT Figure 5 - Particle Phase Total Deposition Rates n PROJECT NAME : C8 2000 Actual Emissions - Vapor Phase Wet Deposition (g/m2/yr) 6/ 7/02 MODELING OPTIONS : CONC, WDEP, RURAL, ELEV, DFAULT, WETDPL RECEPTORS : 3529 OUTPUT TYPE : WDEP MAX: 0.00845 UNITS : g/m **2 ISC-AERMOD View by Lakes Environmental Software DATE : 6/5/2002 j 0.5 km PRJECT/PLOT NO. : C:\ISCVIEW3\WASHINGTON W ORKS\ACT00VR.IS\AN00GALL.PLT . Figure 6 - Vapor Phase Wet Deposition Rates 1?