Localized Significance Threshold Analysis

Transcription

1 Localized Significance Threshold Analysis

2 ANDORA AVENUE SUBDIVISION Tentative Tract No Subsequent EIR Localized Significance Threshold Analysis Prepared for: City of Los Angeles, Department of City Planning 201 N Figueroa Street #4 Los Angeles, California Prepared by: Impact Sciences, Inc. 234 East Colorado Blvd., Suite 205 Pasadena, California November 2008

3 Localized Significance Threshold Analysis SUMMARY The proposed Project is located northwest of the existing Andora Avenue and Plummer Street in the City of Los Angeles, west of the community of Chatsworth in the San Fernando Valley. The project consists of the development of 45 single-family detached residential units on an approximately 15 acre site. The project is located in the South Coast Air Basin (SoCAB). The local air quality enforcement agency in the SoCAB is the South Coast Air Quality Management District (SCAQMD). For projects located in the SoCAB, the SCAQMD recommends the evaluation of localized air quality impacts to sensitive receptors in the immediate vicinity of the project site as a result of construction activities. This evaluation requires that anticipated ambient air concentrations, determined using a computer-based air quality dispersion model, be compared to localized significance thresholds for respirable particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), and carbon monoxide (CO). 1 The significance threshold for PM10 represents compliance with SCAQMD Rule 403 (Fugitive Dust). The threshold for PM2.5 is intended to constrain emissions so as to aid in progress toward attainment of the ambient air quality standards. The thresholds for NO2 and CO represent the allowable increase in concentrations above background levels in the vicinity of the project that would not cause or contribute to an exceedance of the relevant ambient air quality standards. Project construction would begin in 2009 and be complete in mid This study analyzed the impacts of the construction emissions (fugitive dust and motor vehicle and equipment exhaust) on ambient air quality concentrations in the vicinity of the construction site. The maximum impacts for PM10 and PM2.5 were associated with the grading phase of the project while the maximum impacts for NO2 and CO were associated with simultaneous building construction and asphalt paving. The Localized Significance Threshold (LST) analysis showed that the maximum PM10, PM2.5, NO2, and CO concentrations due to construction of the project would not exceed the thresholds of significance established by SCAQMD at nearby sensitive receptors exterior to the project area. 1 South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008). Impact Sciences, Inc. i The Andora Avenue Subdivision November 2008

4 Section TABLE OF CONTENTS Summary...i 1.0 General Project Description Regional Air Quality Thresholds of Significance Calculation of Emissions Grading Phase Building Construction Phase Asphalt Paving Subphase Architectural Coating Subphase Estimated Maximum Daily Emissions Localized Significance Threshold Analysis Modeling Approach Sources Receptors Meteorology and Monitoring Data Model Options Terrain Data Modeling Results Adjustment to NO2 Impacts Project-Specific Impacts Conclusions...12 Page Appendices A B Summary of ISCST3 Modeling Emissions and Results Selected ISCST3 Modeling Output Impact Sciences, Inc. ii The Andora Avenue Subdivision November 2008

5 LIST OF FIGURES Figure Page 1 Wind Rose for the Pomona Monitoring Station...9 LIST OF TABLES Table Page 1 California Ambient Air Quality Standards Designation South Coast Air Basin (Los Angeles County) Peak Background Concentrations for SRA 6 for the Period of 2005 to Localized Significance Thresholds Estimated Maximum Daily On-Site Construction Emissions NO2-to-NOX Ratio as a Function of Downwind Distance Modeling Results Maximum Impacts at Sensitive Receptors...12

6 Localized Significance Threshold Analysis 1.0 GENERAL 1.1 Project Description The proposed Project is located northwest of the existing Andora Avenue and Plummer Street in the City of Los Angeles, west of the community of Chatsworth in the San Fernando Valley. The project consists of the development of 45 single-family detached residential units on an approximately 15 acre site. Specific details regarding project construction are unavailable; however, it was assumed that project construction would begin in 2009 and be complete in mid Sources utilized in the localized significance threshold (LST) analysis include the South Coast Air Quality Management District s (SCAQMD) California Environmental Quality Act (CEQA) Air Quality Handbook and Final Localized Significance Threshold Methodology, air quality data from the California Air Resources Board (CARB), and the URBEMIS2007 Environmental Management Software. Air quality modeling conducted for the analysis was conducted using the Industrial Source Complex Short Term (ISCST3) model, which is an SCAQMD-approved Gaussian dispersion model. 1.2 Regional Air Quality The proposed Project is located within the South Coast Air Basin (SoCAB). An air basin is a land area with similar meteorological and geographic conditions throughout. To the extent possible, air basins include both the air pollutant source and immediate receptor areas. The determination of whether an air basin s air quality is healthful or unhealthful is evaluated by comparing contaminant levels in ambient air samples to national and state standards. Health-based air quality standards have been established by California and the federal government for the following seven criteria air pollutants: (1) ozone (O3), (2) carbon dioxide (CO), (3) nitrogen dioxide (NO2), (4) sulfur dioxide (SO2), (5) respirable particulate matter (PM10), (6) fine particulate matter (PM2.5), and (7) lead. These standards were established to protect sensitive receptors from adverse health impacts due to exposure to air pollution with a margin of safety. California standards are more stringent than the federal standards and in the case of PM10 and SO2, much more stringent. California has also established standards for sulfates, visibility reducing particles, hydrogen sulfide and vinyl chloride, none of which have corresponding federal standards. The US Environmental Protection Agency (US EPA) makes designations for 7 criteria pollutants based on the National Ambient Air Quality Standards (NAAQS). CARB makes designations for 10 criteria pollutants for air basins in California based on the California Ambient Air Quality Standards (CAAQS). CARB will designate an air basin or a portion of an air basin as nonattainment for a pollutant if monitoring data shows that a violation of the CAAQS for a particular pollutant occurred at least once during the previous three years. The status of the SoCAB with respect to attainment with the CAAQS, Impact Sciences, Inc. 1 The Andora Avenue Subdivision November 2008

7 Localized Significance Threshold Analysis which is more stringent than the NAAQS, is summarized below in Table 1, California Ambient Air Quality Standards Designation South Coast Air Basin (Los Angeles County). Table 1 California Ambient Air Quality Standards Designation South Coast Air Basin (Los Angeles County) Pollutant Averaging Time Designation/Classification Ozone (O3) 1 Hour, 8 Hour Nonattainment 1 Carbon Monoxide (CO) 1 Hour, 8 Hour Attainment Nitrogen Dioxide (NO2) 1 Hour Attainment Sulfur Dioxide (SO2) 1 Hour, 24 Hour Attainment Respirable Particulate Matter (PM10) 24 Hour, Annual Arithmetic Mean Nonattainment Fine Particulate Matter (PM2.5) Annual Arithmetic Mean Nonattainment Lead (Pb) 2 30 Day Average Attainment Sulfates (SO4) 24 Hour Attainment Hydrogen Sulfide (H2S) 1 Hour Unclassified Vinyl Chloride 2 24 Hour Unclassified Visibility-Reducing Particles 8 Hour (10 AM 6 PM) Unclassified Source: California Air Resources Board, Area Designations Maps/State and National, CARB has not issued area classifications based on the new state 8-hour standard. The previous classification for the 1-hour ozone standard was Extreme. 2 CARB has identified lead and vinyl chloride as toxic air contaminants with no threshold level of exposure for adverse health effects determined. CARB is required to periodically review ambient air quality standards and make recommendations based on the latest health-based studies to ensure sensitive populations are adequately protected with a margin of safety. In February 2007, CARB approved new standards for NO2, which took effect in March The revised 1-hour NO2 standard was lowered from 0.25 parts per million (ppm) to 0.18 ppm and a new annual arithmetic mean standard was set at ppm. However, CARB has not issued new area designations based on the new state 1-hour and annual arithmetic mean NO2 standard. Therefore, the designation of attainment for the SoCAB is based on the previous 0.25 ppm 1-hour standard. 1.3 Thresholds of Significance The SoCAB is under the jurisdiction of the SCAQMD. For projects located in the SoCAB, the SCAQMD recommends the evaluation of localized air quality impacts to sensitive receptors in the immediate vicinity of the project site as a result of construction activities. This evaluation requires that anticipated Impact Sciences, Inc. 2 The Andora Avenue Subdivision November 2008

8 Localized Significance Threshold Analysis ambient air concentrations, determined using a computer-based air quality dispersion model, be compared to localized significance thresholds for PM10, PM2.5, NO2, and CO. 2 The significance thresholds for NO 2 and CO represent the allowable increase in concentrations above background levels in the vicinity of the project that would not cause or contribute to an exceedance of the relevant ambient air quality standards. The threshold for PM10 represents compliance with Rule 403 (Fugitive Dust), while the threshold for PM2.5 is intended to constrain emissions so as to aid in progress toward attainment of the ambient air quality standards. 3 To monitor the concentrations of the pollutants, the SCAQMD has divided the SoCAB into Source Receptor Areas (SRAs) in which air quality monitoring stations are operated. The project site is located in the West San Fernando Valley SRA (SRA 6). The peak background concentrations measured in SRA 6 for NO2 and CO are listed in Table 2, Peak Background Concentrations for SRA 6 for the Period of 2005 to The LSTs for NO2 and CO are based on these values. Pollutant Table 2 Peak Background Concentrations for SRA 6 for the Period of 2005 to 2007 Averaging Period Unit Peak Concentration Nitrogen Dioxide (NO2) 1 hour ppm Carbon Monoxide (CO) 1 hour ppm Carbon Monoxide (CO) 8 hours ppm Source: South Coast Air Quality Management District, Historical Data by Year, Note: ppm = parts per million As a conservative approach, the significance thresholds for NO2 and CO are based on the difference between the ambient air quality standard and the maximum concentration that occurred during the three previous years for which data is available (2005 to 2007) as shown in Table 2. These values represent the allowable increase in NO2 and CO ambient concentrations above current levels that could occur in SRA 6 without causing or contributing to exceedances of the CAAQS. The threshold for PM10 is a 24-hour average concentration of 10.4 micrograms per cubic meter (µg/m 3 ) based on compliance with Rule 403. The threshold for PM2.5, also set at 10.4 µg/m 3, is intended to constrain emissions so as to not cause or contribute to an exceedance of the ambient air quality standards. The thresholds are listed in Table 3, Localized Significance Thresholds. On-site construction emissions that result in an exceedance of these 2 South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008). 3 Ibid. Impact Sciences, Inc. 3 The Andora Avenue Subdivision November 2008

9 Localized Significance Threshold Analysis thresholds have the potential to generate significant adverse local impacts on ambient air quality. For reference, the most stringent ambient air quality standards (CAAQS or NAAQS) are listed in Table 3. Table 3 Localized Significance Thresholds Pollutant Averaging CAAQS/NAAQS 1 Peak Conc. LST Criteria 2 Period µg/m 3 ppm in ppm µg/m 3 ppm Respirable Particulate Matter (PM10) 24 hours 50 n/a n/a 10.4 n/a Fine Particulate Matter (PM2.5) 24 hours 35 n/a n/a 10.4 n/a Nitrogen Dioxide (NO2) 1 hour Carbon Monoxide (CO) 1 hour 23, , Carbon Monoxide (CO) 8 hours 10, , Sources: South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008). Notes: ppm = parts per million; µg/m 3 = micrograms per cubic meter; n/a = not applicable 1 California has not adopted a 24-hour CAAQS for PM2.5; the 24-hour PM2.5 value shown is the NAAQS. All other standards are the California standards. 2 LSTs for NO2 and CO are based on the difference between CAAQS and the Peak Concentration. 2.0 CALCULATION OF EMISSIONS The localized impacts of a project are evaluated based on the maximum daily emissions that could be generated during construction. Therefore, to determine the maximum daily emissions of NO2, CO, PM10, and PM2.5, unmitigated construction emissions during grading and other earthwork activities were estimated based on the URBEMIS2007 (Version 9.2.4) Environmental Management Software. Model input parameters were based on default URBEMIS2007 values recommended by the SCAQMD and reasonably conservative assumptions. The key assumptions used to estimate the construction emissions for the project are as follows: 2.1 Grading Phase Specific details regarding project construction are unavailable; however, it was assumed that project construction would begin in The grading phase was assumed to last for approximately 2 months. The SCAQMD has developed a default construction equipment mix based on surveys of construction sites throughout the SoCAB. The equipment mix represents the number and types of equipment that would be in operation simultaneously on any given day that would generally result in the highest emissions. The number and types of on-site construction equipment used in this analysis was based on Impact Sciences, Inc. 4 The Andora Avenue Subdivision November 2008

10 Localized Significance Threshold Analysis SCAQMD default equipment mix. In addition, on-site fugitive dust generation is based on the SCAQMD default value. The following bullet-list provides the key factors used in this analysis. Assumed grading schedule: January 2009 through February 2009; Construction equipment: 1 Graders, 1 Rubber Tired Dozer, 1 Tractor/Loader/Backhoe, and 1 Water Truck; Maximum daily acreage disturbed: 3.75 acres (25 percent of the total project size); and On-site fugitive dust: 20 pounds per acre disturbed per day (default value). In addition to the above, the URBEMIS2007 analysis also includes dust control measures required by SCAQMD Rule 403. Compliance with Rule 403 is mandatory for all construction projects. In the URBEMIS2007 model, the emission calculations take into account compliance with Rule 403 by incorporating the watering of exposed surfaces and unpaved roads three times daily, which is estimated to reduce fugitive dust emissions (both PM10 and PM2.5) by a maximum of 61 percent per guidance from the SCAQMD. The emission calculations also take into account the use of soil stabilization measures during equipment loading and unloading, which is estimated to reduce fugitive dust emissions (both PM10 and PM2.5) by a maximum of 69 percent per guidance from the SCAQMD. Rule 403 contains other best available control measures to minimize fugitive dust emissions; however, they are not accounted for in the URBEMIS2007 model. 2.2 Building Construction Phase Building construction was assumed to follow grading and end in mid The number and types of onsite construction equipment used in this analysis was based on SCAQMD default equipment mix. The following bullet-list provides the key factors used in this analysis. Assumed building construction schedule: March 2009 through June 2010; and Grading equipment: 1 Crane, 2 Forklifts, 1 Generator Set, 1 Tractor/Loader/Backhoe, and 3 Welders. 2.3 Asphalt Paving Subphase Asphalt paving was assumed to occur during the initial month of building construction. The number and types of on-site construction equipment used in this analysis was based on SCAQMD default equipment mix. The amount of paving was also based on a default value. The following bullet-list provides the key factors used in this analysis. Assumed paving schedule: March 2009; Paving equipment: 4 Cement and Mortar Mixers, 1 Paver, 2 Paving Equipment, 1 Roller, and 1 Tractor/Loader/Backhoe; Area to be paved: 3.75 acres (25 percent of the total project size); Impact Sciences, Inc. 5 The Andora Avenue Subdivision November 2008

11 Localized Significance Threshold Analysis 2.4 Architectural Coating Subphase Architectural coating was assumed to begin 6 months after building construction and last until the end of construction, in mid The emissions associated with architectural coating are based on SCAQMD rules that govern coating applications and default surface area calculations for single-family structures. URBEMIS2007 does not require any user inputs, except for the schedule, to determine the emissions associated with this phase. 2.5 Estimated Maximum Daily Emissions Based on the analysis, the results indicate that estimated maximum daily on-site emissions of PM10 and PM2.5 are expected to occur in 2009 during the grading phase. The estimated maximum daily on-site emissions of NOX and CO are expected to occur in 2009 during the first month of building construction when asphalt paving is assumed to occur. Only emissions from on-site equipment and activity are applicable to the LST analysis, as per the SCAQMD Final Localized Significance Threshold Methodology. The estimated maximum daily on-site emissions for PM10, PM2.5, NOX, and CO are presented in Table 4, Estimated Maximum Daily On-Site Construction Emissions. Table 4 Estimated Maximum Daily On-Site Construction Emissions Maximum Daily Emissions (pounds per day) Pollutant Fugitive Dust Onsite Mobile Sources Respirable Particulate Matter (PM10) Fine Particulate Matter (PM2.5) Nitrogen Dioxide (NO2) Carbon Monoxide (CO) Source: Construction emissions were estimated based on URBEMIS2007 (Version 9.2.4). Emissions reflect the worst-case scenario (i.e., highest daily emissions associated with the project). The worst-case daily emissions may occur in different project construction phases. 3.0 LOCALIZED SIGNIFICANCE THRESHOLD ANALYSIS 3.1 Modeling Approach Per the recommendation of the SCAQMD, ambient PM10, PM2.5, NO2, and CO concentrations due to the construction of the project were analyzed using methods described in its Final Localized Significance Threshold Methodology. The SCAQMD-approved dispersion model, Industrial Source Complex Short Impact Sciences, Inc. 6 The Andora Avenue Subdivision November 2008

12 Localized Significance Threshold Analysis Term (ISCST3), 4 was used to model the air quality impacts of PM10, PM2.5, NOX, and CO emissions. ISCST3 can estimate the air quality impacts of single or multiple point, area, or volume sources using historical meteorological conditions. Volume sources were used to represent the emissions from trucks and heavy-duty construction equipment. Area sources were used to model fugitive dust emissions of PM10 and PM2.5. For the purpose of the dispersion modeling, the maximum daily emissions that could occur due to construction activities from any construction phase were selected for the LST analysis, as listed in Table 4. The average workday was assumed to be 8 hours long. Therefore, the maximum daily emissions from Table 4 were divided by 8 to obtain maximum emission rates in units of pounds per hour Sources Volume sources were used to represent emissions from construction equipment. Volume sources were placed in areas where construction activity is anticipated to occur. The volume sources covered approximately 3.75-acres representing the maximum daily disturbed area on any given day. An area source was co-located with the volume sources to model fugitive dust emissions of PM10 and PM2.5. Two groups of sources were modeled to determine the maximum impacts at nearby sensitive receptors. One source group was located in the eastern portion of the project site near to existing receptors along Andora Avenue and Trigger Street the east. A second source group was located at the southeastern portion of the project site to model impacts at the existing receptors along Plummer Street to the east and southeast. Emissions from heavy-duty vehicles and construction equipment, modeled as volume sources, were given a 5-meter release height, 4.65-meter initial horizontal dimension, and 1.4-meter initial vertical direction. Fugitive dust emissions from grading activities, modeled as area sources, were given a groundlevel release height and a 1-meter initial vertical dimension. There parameters are standard values for use in volume and area sources Receptors Discrete Cartesian receptors were used to determine air quality impacts in the vicinity of the project site. Near-field receptors were placed at 25-meter intervals outside the boundary of the project site to a minimum distance of 250 meters from the project site. Mid-field receptors were spaced 50 meters apart out to 500 meters. Extended-field receptors were spaced 100 meters apart out to 1.0 kilometers and Lakes Environmental ISC-AERMOD VIEW Software (Version 5.9.0) Impact Sciences, Inc. 7 The Andora Avenue Subdivision November 2008

13 Localized Significance Threshold Analysis meters apart out to 2.0 kilometers in order to cover other potential sensitive receptors. Flagpole receptors were given a height of 2 meters, as recommended in the Final Localized Significance Threshold Methodology Meteorology and Monitoring Data Reseda was identified as the nearest meteorological monitoring station for the project. Monitoring data were obtained from SCAQMD website. 6 For the vicinity of the site, the Reseda 1981 meteorological data file was selected. In this data set, the surface wind speeds and directions were collected at the SCAQMD Reseda Monitoring Station (Station ID 51107), while the upper air sounding data used to estimate hourly mixing heights were gathered from the Ontario International Airport (Station 99999). The surface wind directions are presented graphically in a polar diagram generated by the Wind Rose software. This diagram is shown in Figure 1, Wind Rose for the Pomona Monitoring Station Model Options The SCAQMD has published guidelines for dispersion modeling in the SoCAB. The following SCAQMD model options were used in this analysis and are consistent with SCAQMD modeling policy: Urban land use with simple, intermediate and complex terrain; No gradual plume rise; No stack-tip downwash (the LST analysis does not incorporate point sources); Buoyancy-induced dispersion; Default vertical wind profile exponents; Default vertical potential temperature gradients; Dry deposition and dry plume depletion for PM10 only; No missing data processing; No calms processing; and Averaging periods: 1-hour (CO and oxides of nitrogen [NOX]), 8-hour (CO), 24-hour (PM10 and PM2.5). 5 South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008) South Coast Air Quality Management District, Meteorological Data for Dispersion Modeling, Impact Sciences, Inc. 8 The Andora Avenue Subdivision November 2008

14 WIND ROSE PLOT: RESEDA MONITORING STATION DISPLAY: Wind Speed Direction (blowing from) NORTH 15% 12% 9% 6% 3% WEST EAST WIND SPEED (Knots) >= SOUTH Calms: 12.84% COMMENTS: DATA PERIOD: 1981 Jan 1 - Dec 31 00:00-23:00 COMPANY NAME: Impact Sciences, Inc. CALM WINDS: 12.84% TOTAL COUNT: 8760 hrs. AVG. WIND SPEED: 3.04 Knots DATE: 1/6/2009 PROJECT NO.: SOURCE: WRPLOT View - Lakes Environmental Software, Impact Sciences, Inc. - January 2009 FIGURE 1 Wind Rose for the Pomona Monitoring Station /09

15 Localized Significance Threshold Analysis Terrain Data Terrain heights for all receptors were derived from digital terrain elevations developed by the US Geological Survey by using its Digital Elevation Model (DEM). The DEM data provides terrain elevations with 1-meter vertical resolution and 10-meter horizontal resolution based on a Universal Transverse Mercator (UTM) coordinate system. The UTM coordinates are referenced to either the World Geodetic System of 1984 (WGS 84) or the North American Datum of 1983 (NAD 83). For each receptor location, the terrain elevation was set to the elevation for the closest DEM grid point. 3.2 Modeling Results Adjustment to NO2 Impacts The Final Localized Significance Threshold Methodology discusses an adjustment of the NO2 impacts due to the fact that most of NOX in the combustion exhaust will occur in the form of nitric oxide (NO), rather than as NO2. Nitric oxide is converted in the atmosphere through chemical reactions to NO2. The LST methodology discusses this adjustment as follows: NOX emissions are simulated in the air quality dispersion model and the NO2 conversion rate is treated by a NO2-to-NOX ratio, which is a function of downwind distance. Initially, it is assumed that only 5 percent of the emitted NOX is NO2. At 5,000 meters downwind, 100 percent conversion of NO-to-NO2 is assumed. 7 Table 5, NO2-toNOX Ratio as a Function of Downwind Distance, from the Final Localized Significance Threshold Methodology, demonstrates how the NO2-to-NOX ratio varies with distance from the source. To determine the NO2-to-NOX ratios for this analysis, the maximum impacted residential and school receptors were determined. The distance from the center of the source area to the particular receptor was determined and each corresponding NO2-to-NOX ratio from Table 5 was applied to the modeled concentrations. Ratios at distances between the values in Table 5 were interpolated. 7 South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2003) 2-8. The NO2 conversion rates are adapted by the SCAQMD from Arellano, J.V., A.M. Talmon, and P.J.H. Builtjes, A Chemically Reactive Plume Model for the NO-NO2-O3 System, Atmospheric Environment 24A, Impact Sciences, Inc. 10 The Andora Avenue Subdivision November 2008

16 Localized Significance Threshold Analysis Table 5 NO2-to-NOX Ratio as a Function of Downwind Distance Downwind Distance (meters) NO2-to-NOX Ratio , , , , , Source: South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008) Table 2-4, p Project-Specific Impacts The results of the dispersion modeling are present in Table 6, Modeling Results Maximum Impacts at Sensitive Receptors. Table 6 shows the maximum PM10, PM2.5, NO2, and CO concentrations at sensitive receptors due to emissions associated with the project. When the results of the modeling analysis are compared to the thresholds, the maximum PM10, PM2.5, NO2, and CO concentrations are not expected to exceed the thresholds of significance at any sensitive receptor. It should be noted that the NO2 concentrations reflect the use of the SCAQMD guidance on NOX-to-NO2 conversion, as outlined in the previous section. Impact Sciences, Inc. 11 The Andora Avenue Subdivision November 2008

17 Localized Significance Threshold Analysis Table 6 Modeling Results Maximum Impacts at Sensitive Receptors Pollutant Averaging Model Results LST Criteria 1 Period µg/m 3 ppm µg/m 3 ppm Exceeds Threshold? Respireable Particulate Matter (PM10) 24 hours 6.00 n/a 10.4 n/a NO Fine Particulate Matter (PM2.5) 24 hours 1.70 n/a 10.4 n/a NO Nitrogen Dioxide (NO2) 1 hour NO Carbon Monoxide (CO) 1 hour , NO Carbon Monoxide (CO) 8 hours , NO Source: Impact Sciences, Inc., (2008). Note: ppm = parts per million; n/a = not applicable 1 South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008). The maximum impacts were observed at the residential areas north and east of the project site. 4.0 CONCLUSIONS The results of the modeling analysis indicate that the maximum PM10, PM2.5, NO2, and CO concentrations are not expected to exceed the thresholds of significance at any sensitive receptor. The project is still required to implement fugitive dust control mitigation measures, as recommended by SCAQMD Rule 403 (Fugitive Dust). The full effect of these mitigation measures is not taken into account in the dispersion modeling, which would tend to reduce the PM10 and PM2.5 concentrations listed in Table 6. Impact Sciences, Inc. 12 The Andora Avenue Subdivision November 2008

18 APPENDIX A Summary of ISCST3 Modeling Emissions and Results

19 Andora Avenue Subdivision Project ISCST3 - Model Emission Rate Inputs Table LST-1 LST Emission Rates Project Model Averaging Number of Number of Modeled Emission Rate* Component Source Period Volume Sources Area Sources CO NOx PM10 PM10 (DPM) PM10 (Dust) PM2.5 PM2.5 (DPM) PM2.5 (Dust) Group (Hours) (Exhaust) (Dust) lbs/day g/s lbs/day g/s lbs/day lbs/day g/s lbs/day g/s lbs/day lbs/day g/s lbs/day g/s NE 3.75 Acre Area** VOL E E E #DIV/0! E #DIV/0! Area #DIV/0! 0.00 #DIV/0! #DIV/0! E #DIV/0! E-02 SE 3.75 Acre Area** VOL E E E #DIV/0! E #DIV/0! Area #DIV/0! 0.00 #DIV/0! #DIV/0! E #DIV/0! E-02 Notes: * Maximum CO and NO X emissions are associated with building construction and paving. Maximum PM 10 and PM 2.5 emissions are associated with grading and excavation. ** For modeling purposes, two source groups were analyzed. One was located at the northern end of the project site and a second was located at the southern end of the project site to determine impacts at the downwind receptors. Table LST-2 PM 10 Dry Depletion Parameters Microns Fraction Density Source: South Coast Air Quality Management District, Final Localized Significance Threshold Methodology, (2008).

20 Andora Avenue Subdivision Project ISCST3 - Model Results Table LST-3 Maximum Modeled Impacts at Sensitive Receptors and NO 2 Conversion Project Model Receptor Modeled Impacts at Sensitive Receptors (All Source Groups) Component Source Type CO NO X PM 10 PM 2.5 Group 1-Hr 8-Hr 1-Hr 24-Hr 24-Hr µg/m 3 µg/m 3 µg/m 3 µg/m 3 µg/m 3 Northeast VOL01-36, Area1 Residential Southeast VOL37-72, Area2 Residential Project Model Receptor Maximum Modeled Impacts at Sensitive Receptors Component Source Type CO NO X PM 10 PM 2.5 Group 1-Hr 8-Hr 1-Hr 24-Hr 24-Hr µg/m 3 ppm µg/m 3 ppm µg/m 3 µg/m 3 µg/m 3 Southeast VOL37-72, Area2 Residential Project Model Receptor Conversion to NO 2 Component Source Type NO X NO 2 -NO X NO 2 -NO X NO 2 Group 1-Hr Distance Ratio 1-Hr µg/m 3 meters µg/m 3 ppm Northeast VOL01-36, Area1 Residential Southeast VOL37-72, Area2 Residential Source: Lakes Environmental, ISC-AERMOD View, Version 5.9.0

21 APPENDIX B Selected ISCST3 Modeling Output (Complete Modeling Files Available Upon Request)

22 CO 1-Hour * ISCST3 (02035): C:\ISC-AERMOD\947.02\LST\CO.ISC * MODELING OPTIONS USED: * CONC URBAN ELEV FLGPOL NOCALM * PLOT FILE OF HIGH 1ST HIGH 1-HR VALUES FOR SOURCE GROUP: SRCGP2 * FOR A TOTAL OF 3056 RECEPTORS. * FORMAT: (3(1X,F13.5),1X,F8.2,3X,A5,2X,A8,2X,A4,6X,A8) * X Y AVERAGE CONC ZELEV AVE GRP HIVAL NET ID * HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA

23 CO 8-Hour * ISCST3 (02035): C:\ISC-AERMOD\947.02\LST\CO.ISC * MODELING OPTIONS USED: * CONC URBAN ELEV FLGPOL NOCALM * PLOT FILE OF HIGH 1ST HIGH 8-HR VALUES FOR SOURCE GROUP: SRCGP2 * FOR A TOTAL OF 3056 RECEPTORS. * FORMAT: (3(1X,F13.5),1X,F8.2,3X,A5,2X,A8,2X,A4,6X,A8) * X Y AVERAGE CONC ZELEV AVE GRP HIVAL NET ID * HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA

24 NOx 1-Hour * ISCST3 (02035): C:\ISC-AERMOD\947.02\LST\NOX.ISC * MODELING OPTIONS USED: * CONC URBAN ELEV FLGPOL NOCALM * PLOT FILE OF HIGH 1ST HIGH 1-HR VALUES FOR SOURCE GROUP: SRCGP2 * FOR A TOTAL OF 3056 RECEPTORS. * FORMAT: (3(1X,F13.5),1X,F8.2,3X,A5,2X,A8,2X,A4,6X,A8) * X Y AVERAGE CONC ZELEV AVE GRP HIVAL NET ID * HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA

25 PM10 24-Hour * ISCST3 (02035): C:\ISC-AERMOD\947.02\LST\PM10.ISC * MODELING OPTIONS USED: * CONC DDEP URBAN ELEV FLGPOL TOXICS NOCALM ARDPLT * PLOT FILE OF HIGH 1ST HIGH 24-HR VALUES FOR SOURCE GROUP: SRCGP2 * FOR A TOTAL OF 3056 RECEPTORS. * FORMAT: (4(1X,F13.5),1X,F8.2,3X,A5,2X,A8,2X,A4,6X,A8) * X Y AVERAGE CONC DRY DEPO ZELEV AVE GRP HIVAL NET ID * HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA

26 PM Hour * ISCST3 (02035): C:\ISC-AERMOD\947.02\LST\PM25.ISC * MODELING OPTIONS USED: * CONC URBAN ELEV FLGPOL NOCALM * PLOT FILE OF HIGH 1ST HIGH 24-HR VALUES FOR SOURCE GROUP: SRCGP2 * FOR A TOTAL OF 3056 RECEPTORS. * FORMAT: (3(1X,F13.5),1X,F8.2,3X,A5,2X,A8,2X,A4,6X,A8) * X Y AVERAGE CONC ZELEV AVE GRP HIVAL NET ID * HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA HR SRCGP2 1ST NA