Document nkak3QkYZg0oL9ny753JkEgo8

AR226-2649 39 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 of 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 of 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 of the scavenging coefficient can be entered into the ISC3 model, the largest scavenging coefficient was chosen to ensure that the mode1 predictions 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 of 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 ofon-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 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 vapor concentrations and annual deposition rates over the entire receptor grid. A contour plot of 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 jig/m3 Particle Phase: Maximum Dry Deposition Rate = 0.1347 g/nr/yr Maximum Wet Deposition Rate = 0.0456 g/n^/yr Maximum Total Deposition Rate =0.1803 g/nr/yr Vapor Phase: Maximum Wet Deposition Rate = 0.0085 g/iT^/yr The maximum ground-level concentration and all of 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 Ib/yr) Total Wet Deposition = 12,608 g/yr (27.8 Ib/yr) Total Deposition = 19,340 g/yr (42.6 Ib/yr) Total Wet Deposition = 1,644 g/yr (3.6 Ib/yr) Table 1 Stack Parameters 1823A 815D 815D T7IME 662 T6IFCE 644 T6IZCE 699 1353A 164-5E 652 Pre-Existing 164-2E 658 614A 163-E-26 231 614A 163-E-ll 232 781 163-E-33 216 1953 242 242 2365A C1FSE 274 2365A C1FKE 268 2365A C1CAE 205 Semiworks Application R022EEF6 Semiworks Application R022EEF86 Semiworks Application R022EEF87 Semiworks Application R022EEF89 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 180003 9,800 2,800 500 600 2,750 1,250 1,000 100 1,000 8836 7540 1885 3770 '''Vent ID T61ZCE consists of 18 one-foot diameter vents. The flow rate given is the total for all 18 vents. The velocity listed is the velocity calculated for one individual vent. 40.2 169.8 21.213 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 Table 2 Emission Information T7IME 662 T6IFCE 644 T6IZCE 699 164-5E 652 164-2E 658 163-E-26 231 163-E-ll 232 163-E-33 216 242 242 C1FSE 274 C1FKE 268 C1CAE 205 R022EEF6 R022EEF86 R022EEF87 R022EEF89 0 0.54 0.9 0.9 0.9 0.11 0.09 0 0.9 0.03 1 1 1 1 1 1 1 0.46 0.1 0.1 0.1 0.89 0.91 1 0.1 0.97 0 0 0 0 0 0 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 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 Scavengm; i Liquid Precipitation (s-'/mm-h'1) Coefficients Frozen Precipitation (s-'/mm-h-1) 1.2x10-4 5x10-5 4xl0"5 4xl0-5 1.67xl0-5 1.33x10"' 1.3xl0-4 2.8x10-4 4.33x10-' 9.33x10-' Vapor Phase: Liquid Scavenging Coefficient (s-'/mm-h-1) = Frozen Scavenging Coefficient (s-'/mm-h-1) = 6.4x10-6 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 ofs-'/n-im-h-', 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 IxlO-2 --X----X---- = 6.4xl0-6 = 6.4xl0-6 ---------- hr 3600.9 1mm s mm mm hr 434690CH 434680CH 4346700 4346600 4346500-^ 441600 441700 441800 441900 442000 Figure I - Building Plot Plan 442100 =@ Co |Fel J All | Tao Nail, ERI [1X El -of=12\ h AY e oS 434850Ch 43480004347500434700043465004346000- 441000 4-4-4-4-4-4-4-4- + + + + + + + 4-4-4-4-4-4-4- + + + + + + + + 4-4-4-4-4-4-4-4- + + + + + + + + 4- + + + + 4- + + + + + + + + ++++++++ + + + + + + + +++++++ ++++++++ ++++++++ + + + + + + + +++++++ + + + + + + + + +++++++ + + + + + + + + +++++++ + + + + + + + + + + + + + ++ + + + + + + + + +++++++ +++++++ +++++++ +++++++ +++++++ ++++++++++++ +++++++++++4 +++4-++4-4-++4-+ 4- + 4- + + + 4- 4-4-4-4-4-4-44-4-4-4-4-4-4- ^^- .^^^ ^ - i~^~ t ^ ^ ^^r' , i-t-i -i- -i-lr-^ i 441500 i-------------------- 442000 442500 -j-4^^- 443000 443500 444000 Figure 3 Little Hocking Well Watershed Receptors Modeled 44450 4349000 C8 2000 Actual Emissions Annual Average Air Concentrations (ug/m3) 434800CH 4347000-d 4346000-^ 4345000 439000 440000 441000 442000 443000 444000 44 Figure 4 Maximum Ground-Level Concentrations PROJECT NAME C8 2000 Actual Emissions - Partlculate Phas Total Deposition (g/m2/yr) MODELING OPTIONS ; CONC, DEPOS, DDE RURAL, ELEV, DFAU DRYDPL, WETDPL RECEPTORS: 3529 OUTPUT TYPE: DEPOS MAX: 0.18029 UNIT g/m DATE; 6/6/2002 ISC-AERMOD View by Lakes Environmenlal Software PROJECtfPLOT NO.: C:\ISCVIEW3\WASHINGTONWORKS\ACTOOPR.IS\ Figure 5 - Particle Phase Total Deposition Rates PROJECT NAME : C8 2000 Actual Emissions - Vapor Phase Wet Deposition (g/m2/yr) MODELING OPTIONS CONC, WDEP, R DFAULT, WETD RECEPTORS ; 3529 OUTPUT TYPE; WDEP MAX: 0.00845 DATE: 6/5/2002 1SC-AERMOD View by Lakes Environmental Software PROJECT/PLOT NO. CMSCVIEW31WASHINGTON WORKSWCTOO Figure 6 - Vapor Phase Wet Deposition Rates