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### July 20, 2012 Project No. 29-23586A

Mr. Gerardo Rios U.S. Environmental Protection Agency, Region 9 75 Hawthorne Street San Francisco, California 94105 Subject: Class II Area Visibility Analysis Sierra Pacific Industries Biomass-Fired Cogeneration Project Anderson, California

Dear Mr. Rios: This letter provides information regarding a Class II area visibility analysis developed in response to an e-mail sent by Cleveland Holladay of U.S. EPA Region 9 on July 6, 2012, requesting that SPI assess the potential for the biomass-fired cogeneration project proposed for installation at SPI”s Anderson facility to cause visual impairment in potentially sensitive Federal and State Class II areas, as required by 40 CFR Part 52.21(o). Potentially sensitive areas were identified using Google Earth, as well as U.S. Forest Service ( http://www.fs.fed.us ) and California Department of Parks and Recreation ( http://www.parks.ca.gov ) websites. This effort revealed two Federal areas, and two State areas within 50 kilometers (km) of the Anderson facility:

 Sacramento River National Wildlife Refuge (NWR)

 Whiskeytown National Recreation Area (NRA)

 Shasta State Historic Park (SHP)

 William B. Ide Adobe SHP The Sacramento River NWR is composed of 27 units along the Sacramento River between Red Bluff and Princeton, California, totaling 10,146 acres. The closest unit is approximately 38.8 km south-southeast of the facility, and most of the 6 northernmost units lie within 50 km of the facility. Whiskeytown NRA encompasses 42,497 acres, and is located between 18.3 and 37.1 km to the northwest of the facility. The Shasta SHP is located approximately 20 km northwest of the facility, covers approximately 19 acres in the town of Shasta, and consists of four restored or reconstructed buildings, some ruins, and a cemetery along State Route 299. William B. Ide Adobe SHP is located approximately 32 km south-southeast of the facility, covers approximately 4 acres, and consists of three historic structures, a visitor’s center, and a picnic area. The two Federal areas were included in the Class II area visibility analysis, but the two State areas were not. The historic parks are much smaller, and the exhibits are not subject to potential visual impacts from a stack plume in the same way that larger, wild areas are (e.g., Sacramento River NWR and Whiskeytown NRA).

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 2 The visibility impact analyses of the Sacramento River NWR and Whiskeytown NRA were conducted using the plume visibility impact screening model VISCREEN. The model was exercised in accordance with guidance provided in “Workbook for Plume Visual Impact Screening and Analysis (Revised)” (EPA–454/R–92–023; hereafter referred to as “the Workbook”). Level 1 screening analyses, which use worst-case meteorological conditions to provide a conservative estimate of plume visual impacts, were developed for both Class II areas of concern. Inputs required for Level 1 are: 1) maximum expected short-term emission rates, 2) the maximum and minimum distances to each area of concern, and 3) a background visual range for each area of concern. Particulate matter (PM) and oxides of nitrogen (NO X 

### ) emission rates of 9.36 pounds per hour (lb/hr) and 70.2 lb/hr, respectively, were used, and primary NO 2 

### , elemental carbon, and primary sulfate emission rates were assumed to be zero as suggested by the Workbook. The maximum and minimum distances mentioned above were used for the areas of concern (the maximum distance for the Sacramento River NWR was limited to 50 km, though the maximum distance to the most distant unit of the NWR is over 120 km from the facility). Background visual ranges of 110 km for the Sacramento NWR and 60 km for the Whiskeytown NRA were obtained from Figure 9 on page 26 of the Workbook. The results of the Level 1 screening analyses indicated that some of the screening criteria were exceeded, necessitating a Level 2 screening analysis. The default screening criteria suggested in the Workbook were used: a plume perceptibility (ΔE) of 2.0, and a green color contrast value (C p 

### ) of 0.05. Level 2 screening analyses are similar to Level 1 analyses except situation-specific information can be used for particle size distributions, as well as meteorology and plume transport and dispersion patterns. Particle size distribution data specific to the cogeneration unit or the areas of concern were not available, so the Level 1 default were used. The five years of meteorological data from Redding Airport (KRDD) developed for use with AERMOD to predict ambient concentrations in Class II areas for the March 2010 permit application were used to develop joint frequency distributions organized by Pasquill-Gifford stability class, wind speed in meters per second (m/s), wind direction, and time of day. Per the guidance provided by the Workbook, the frequency distributions were stratified using four time-of-day “bins”: 0001 to 0600, 0601 to 1200, 1201 to 1800, and 1801 to 2400. Wind speed bins are defined by the maximum represented wind speed (e.g., the “3 m/s” wind speed bin contains wind speeds from 2.01 to 3 m/s). Wind direction bins were based on the sixteen cardinal directions (e.g., the north-northwest, or NNW, bin contains winds from angles between 326.25° and 348.75°). The Workbook suggests that, if available, visual range data from locations near the source area and area of concern can be used for the Level 2 analysis in place of the default values used in the Level 1 analyses. Table 10 of the “Federal Land Managers’ Air Quality Related Values Work Group (FLAG) Phase 1 Report – Revised (2010)” includes calculated monthly average natural range visual ranges for all Class I areas. For the Whiskeytown NRA, the median visual range for the Yolla-Bolly-Middle Eel Wilderness Area (258 km) was used, and, for the Sacramento River NWR, the median visual range for Lassen Volcanic National

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 3 Park (267 km) was used. In both cases (and particularly in the case of the Sacramento River NWR), the Class I area is located at higher elevations, and has greater visual range than the Class II area of concern. The use of Class I area visual ranges adds considerable conservatism to the analyses. Worst-case dispersion conditions were calculated and ranked for each area of concern according to guidance in the Workbook. Dispersion conditions were represented by the product of σ y 

### (the horizontal Pasquill-Gifford diffusion coefficient, calculated per Appendix E of the Workbook), σ z 

### (the vertical Pasquill-Gifford diffusion coefficient, calculated per Appendix E of the Workbook), and u (the wind speed). Dispersion conditions were calculated for the following combinations of stability class and wind speed, as suggested by the Workbook:

 Stability Class F & Wind Speeds of 1, 2, and 3 meters per second (m/s)

 Stability Class E & Wind Speeds of 1, 2, 3, 4, and 5 m/s

 Stability Class D & Wind Speeds of 1, 2, 3, 4, 5, 6, 7, and 8 m/s For each dispersion condition defined for a given stability class and wind speed, a frequency of occurrence was obtained from the joint frequency distribution for the worst-case wind direction (i.e., the wind-direction sector most likely to transport a plume from the facility tothe area of concern – winds from the southeast for Whiskeytown NRA, and from the northnorthwest for Sacramento River NWR), for each of the four time-of-day bins. The dispersion condition values (i.e., the product σ y 

### σ z 

### u) were then ranked, with the smallest value being the worst-case condition. Cumulative frequencies were calculated starting with the worst-case condition for each time-of-day bin, and the worst-case condition with a cumulative frequency of one percent or greater was evaluated using VISCREEN. Table 1 attached to this letter provides the dispersion conditions and frequencies for Whiskeytown NRA, and Table 2 provides analogous information for Sacramento River NWR. Tables 3 and 4 provide cumulative frequencies for Whiskeytown NRA and Sacramento River NWR, respectively; ineach case, the minimum cumulative frequency that exceeded one percent for each time-ofday bin is indicated by a bold border. Based on the results shown in Table 2, the Level 2 Whiskeytown NRA analysis used stability class D, and a wind speed of 5 m/s; the Level 2 Sacramento River NWR analysis used stability class F and a wind speed of 3 m/s as indicated by the results in Table 4. The results of these analyses are presented in Table 5 for Whiskeytown NRA and in Table 6 for Sacramento River NWR. The default Level 1 screening criteria (i.e., ΔE < 2.0 C p 

### < 0.05) were used to assess potential impacts. VISCREEN, which was developed to assess impacts in Class I areas, provides the maximum predicted visual impacts for two backgrounds (sky and terrain) and two scattering angles (i.e., the angle between the sun’s position and the line of sight) for an observer located inside the area of concern, and the same two background and two scattering angles for an observer located outside the area of concern. Visual impacts outside the area of concern involve plumes that do not interact with, but could potentially be observed from inside the area of concern. Tables 5 and 6 present results for observers located inside as well as outside the

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 4 areas of concern, but, because these analyses are concerned with impacts inside the areas of concern, only the results for an observer located inside the areas of concern are considered when assessing the potential for the project to contribute to visibility impairment. As shown by the VISCREEN Level 2 results for an observer inside the two areas of concern in Tables 5 and 6, the proposed project is predicted to not have the potential to contribute to visibility impairment at sensitive Class II areas within 50 km. We believe that the information provided in this letter addresses the information requested by Region 9, and should be considered to amend the submitted PSD permit application. Please let me know if Region 9 requires any additional information to finalize the draft permit. If you or your staff has any additional questions or need additional information, please do not hesitate to contact me at 425.412.1804. Sincerely yours, ENVIRON INTERNATIONAL, INC.

Eric Albright Senior Manager

Enclosures cc: Omer Shalev, USEPA Region 9 Cleveland Holladay, USEPA Region 9 Ross Bell, Shasta County Air Pollution Control District Shane Young, Sierra Pacific Industries Dave Brown, Sierra Pacific Industries

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 5

**Table 1 Dispersion Condition Frequencies for Whiskeytown NRA** 

**Stability**

**Class Wind**  **Speed (m/s)**  **σ y**  **σ z**  **u (m**  **3 /s)**  **Transport Time**  **(hr) Frequency** 

**0001-0600 0601-1200 1201-1800 1801-2400**  F 1 27,270 10.2 0.000 0.000 0.000 0.000 F 2 54,541 3.4 0.002 0.000 0.001 0.002 E 1 73,370 10.2 0.000 0.000 0.000 0.000 F 3 81,811 2.6 0.003 0.000 0.000 0.003 E 2 146,740 2.0 0.000 0.000 0.000 0.000 D 1 177,519 10.2 0.000 0.000 0.000 0.000 E 3 220,110 2.6 0.001 0.000 0.000 0.001 E 4 293,480 1.5 0.002 0.000 0.000 0.002 D 2 355,039 1.7 0.000 0.000 0.000 0.000 E 5 366,850 1.5 0.001 0.000 0.000 0.001 D 3 532,558 1.3 0.000 0.000 0.000 0.000 D 4 710,078 1.5 0.000 0.000 0.000 0.000 D 5 887,597 1.1 0.000 0.000 0.000 0.001 D 6 1,065,117 0.9 0.000 0.000 0.000 0.001 D 7 1,242,636 0.8 0.000 0.000 0.000 0.000 D 8 1,420,155 0.7 0.000 0.000 0.000 0.000

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 6

**Table 2 Dispersion Condition Frequencies for Sacramento River NWR** 

**Stability**

**Class Wind**  **Speed (m/s)**  **σ y**  **σ z**  **u (m**  **3 /s)**  **Transport Time**  **(hr) Frequency** 

**0001-0600 0601-1200 1201-1800 1801-2400**  F 1 66,449 21.6 0.000 0.000 0.000 0.000 F 2 132,897 7.2 0.006 0.002 0.001 0.002 E 1 189,490 21.6 0.000 0.000 0.000 0.000 F 3 199,346 5.4 0.010 0.002 0.001 0.003 E 2 378,981 4.3 0.000 0.000 0.000 0.000 D 1 517,083 21.6 0.000 0.000 0.000 0.000 E 3 568,471 5.4 0.001 0.001 0.000 0.001 E 4 757,961 3.1 0.007 0.001 0.001 0.004 E 5 947,451 2.4 0.002 0.001 0.000 0.002 D 2 1,034,166 3.1 0.000 0.000 0.000 0.000 D 3 1,551,249 4.3 0.000 0.002 0.001 0.000 D 4 2,068,332 3.1 0.000 0.002 0.001 0.000 D 5 2,585,415 2.4 0.001 0.002 0.002 0.002 D 6 3,102,498 2.0 0.001 0.002 0.003 0.003 D 7 3,619,581 1.7 0.000 0.001 0.002 0.001 D 8 4,136,664 1.4 0.000 0.000 0.001 0.000

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 7

**Table 3 Cumulative Dispersion Condition Frequencies for Whiskeytown NRA** 

**Stability**

**Class Wind**  **Speed (m/s)**  **σ y**  **σ z**  **u (m**  **3 /s)**  **Transport Time**  **(hr) Cumulative Frequency** 

**0001-0600 0601-1200 1201-1800 1801-2400** F 1 27,270 10.2 0.000 0.000 0.000 0.000 F 2 54,541 3.4 0.002 0.000 0.001 0.002 E 1 73,370 10.2 0.002 0.000 0.001 0.002 F 3 81,811 2.6 0.006 0.000 0.001 0.005 E 2 146,740 2.0 0.006 0.001 0.001 0.005 D 1 177,519 10.2 0.006 0.001 0.001 0.005 E 3 220,110 2.6 0.006 0.001 0.001 0.006 E 4 293,480 1.5 0.009 0.001 0.001 0.008 D 2 355,039 1.7 0.009 0.001 0.001 0.008 E 5 366,850 1.5 0.009 0.001 0.001 0.009 D 3 532,558 1.3 0.009 0.001 0.001 0.009 D 4 710,078 1.5 0.010 0.001 0.001 0.009 D 5 887,597 1.1 0.010 0.001 0.002 0.011 D 6 1,065,117 0.9 0.010 0.001 0.002 0.012 D 7 1,242,636 0.8 0.010 0.001 0.002 0.012 D 8 1,420,155 0.7 0.010 0.001 0.002 0.012

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 8

**Table 4 Cumulative Dispersion Condition Frequencies for Sacramento River NWR** 

**Stability**

**Class Wind**  **Speed (m/s)**  **σ y**  **σ z**  **u (m**  **3 /s)**  **Transport Time**  **(hr) Cumulative Frequency** 

**0001-0600 0601-1200 1201-1800 1801-2400**  F 1 66,449 21.6 1 0.000 0.000 0.000 0.000 F 2 132,897 7.2 0.006 0.002 0.001 0.002 E 1 189,490 21.6 1 0.006 0.002 0.001 0.002 F 3 199,346 5.4 0.016 0.004 0.001 0.005 E 2 378,981 4.3 0.016 0.005 0.001 0.005 D 1 517,083 21.6 1 0.016 0.005 0.001 0.005 E 3 568,471 5.4 0.018 0.006 0.002 0.006 E 4 757,961 3.1 0.024 0.007 0.002 0.009 E 5 947,451 2.4 0.026 0.007 0.002 0.012 D 2 1,034,166 3.1 0.026 0.008 0.002 0.012 D 3 1,551,249 4.3 0.026 0.009 0.003 0.012 D 4 2,068,332 3.1 0.026 0.011 0.004 0.012 D 5 2,585,415 2.4 0.027 0.013 0.006 0.014 D 6 3,102,498 2.0 0.028 0.014 0.009 0.016 D 7 3,619,581 1.7 0.029 0.015 0.011 0.018 D 8 4,136,664 1.4 0.029 0.015 0.011 0.018 1 Transport times greater than 12 hours are not included in the cumulative frequency totals.

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 9

**Table 5 Whiskeytown NRA Level 2 VISCREEN Results** 

**Observer Location**  **Background Theta**  **1 (degrees)**  **Distance 2**  **(km) Perceptibility**  **3 (ΔE)**  **Contrast 3**  **(Cp)** Inside Sky 10 37.1 0.408 0.005 Inside Sky 140 37.1 0.24 -0.003 Inside Terrain 10 37.1 0.911 0.007 Inside Terrain 140 37.1 0.187 0.001 Outside Sky 10 1.0 3.278* 0.041 Outside Sky 140 1.0 1.993 -0.027 Outside Terrain 10 1.0 6.999* 0.058* Outside Terrain 140 1.0 1.493 0.009 1 The angle between direct solar radiation and the observer’s line of sight. If the observer were looking directly towards the sun, the angle would be zero degrees; if the observer were looking away from the sun, the angle would be 180 degrees. 2 Plume parcel downwind distance from source. 3 An asterisk (*) indicates absolute values that exceed the default screening criteria. The default screening criteria are: a plume perceptibility (ΔE) of 2.0, and a green color contrast value (Cp) of 0.05. Negative contrast values indicate a plume that appears darker than the background.

### Mr. Gerardo Rios SPI-Anderson Biomass-Fired Cogeneration Project July 20, 2012 Page 10

**Table 6 Sacramento River NWR Level 2 VISCREEN Results** 

**Observer Location**  **Background Theta**  **1 (degrees)**  **Distance 2**  **(km) Perceptibility**  **2 (ΔE)**  **Contrast 2**  **(Cp)** Inside Sky 10 50.0 0.724 0.01 Inside Sky 140 50.0 0.47 -0.006 Inside Terrain 10 38.9 1.209 0.008 Inside Terrain 140 38.9 0.104 0.001 Outside Sky 10 1.0 6.832* 0.121* Outside Sky 140 1.0 1.465 -0.043 Outside Terrain 10 1.0 9.892* 0.104* Outside Terrain 140 1.0 1.385 0.024 1 The angle between direct solar radiation and the observer’s line of sight. If the observer were looking directly towards the sun, the angle would be zero degrees; if the observer were looking away from the sun, the angle would be 180 degrees. 2 Plume parcel downwind distance from source. 3 An asterisk (*) indicates absolute values that exceed the default screening criteria. The default screening criteria are: a plume perceptibility (ΔE) of 2.0, and a green color contrast value (Cp) of 0.05. Negative contrast values indicate a plume that appears darker than the background.