Solar Development and Dust in San Luis Valley Study Area July 2016 TABLE OF CONTENTS NOTATION .............................................................................................................................. ix EXECUTIVE SUMMARY ...................................................................................................... ES-1 ES.1 Purpose of the Study ................................................................................................. ES-1 ES.2 Background on Climate and Air Quality ................................................................... ES-3 ES.2.1 General Information ..................................................................................... ES-3 ES.2.2 Climate ......................................................................................................... ES-4 ES.2.3 Particulate Matter ......................................................................................... ES-4 ES.2.4 PM Sources .................................................................................................. ES-4 ES.2.5 Air Quality Measures ................................................................................... ES-5 ES.2.6 Existing Air Quality in the San Luis Valley-Taos Plateau .......................... ES-6 ES.3 Study Methods and Data ........................................................................................... ES-8 ES.3.1 Construction Activity Assumptions and Model ........................................... ES-9 ES.3.2 Wind-Blown Dust Modeling for Operations................................................ ES-10 ES.4 Results for the San Luis Valley-Taos Plateau ........................................................... ES-12 ES.4.1 Construction Impacts Analysis .................................................................... ES-12 ES.4.2 Operations Impact Analysis ......................................................................... ES-19 ES.4.2.1 Scenarios Analyzed ...................................................................... ES-19 ES.4.2.2 Results for Operations Impacts .................................................... ES-20 ES.4.2.3 Effectiveness of Dust Suppressants to Control Dust ................... ES-25 ES.5 Potential Health Impacts ........................................................................................... ES-25 ES.6 Summary and Conclusions ........................................................................................ ES-27 1 INTRODUCTION ............................................................................................................... 1 1.1 Purpose of the Study ................................................................................................. 1 1.2 Organization of the Report ........................................................................................ 3 2 BACKGROUND ON CLIMATE AND AIR QUALITY .................................................... 5 2.1 General Information .................................................................................................. 5 2.2 Climate ...................................................................................................................... 5 2.2.1 Wind ............................................................................................................... 6 2.2.1.1 Saguache ........................................................................................ 6 2.2.1.2 Alamosa .......................................................................................... 8 2.2.1.3 Taos ................................................................................................ 8 2.2.2 Temperature ................................................................................................... 8 2.2.3 Precipitation ................................................................................................... 10 2.2.4 Severe Weather Events ................................................................................... 10 2.3 Particulate Matter ...................................................................................................... 12 2.4 Particulate Matter Sources ........................................................................................ 13 2.5 Air Quality Measures ................................................................................................ 14 2.5.1 National Ambient Air Quality Standards ....................................................... 14 iii Solar Development and Dust in San Luis Valley Study Area July 2016 TABLE OF CONTENTS (Cont.) 2.5.2 Prevention of Significant Deterioration ......................................................... 16 2.6 Existing Air Quality in the San Luis Valley-Taos Plateau ........................................ 16 2.6.1 Data from SLAMS Sites ................................................................................ 19 2.6.2 Data from IMPROVE Sites ............................................................................ 22 2.6.3 Summary ........................................................................................................ 24 3 STUDY METHODS AND DATA ...................................................................................... 27 3.1 Construction Activity Assumptions and Model ........................................................ 27 3.1.1 Antonito Southeast SEZ ................................................................................. 29 3.1.2 De Tilla Gulch SEZ ........................................................................................ 30 3.1.3 Los Mogotes East SEZ ................................................................................... 31 3.2 Wind-Blown Dust Modeling for Operations ............................................................. 31 3.2.1 Assumptions and Model Used........................................................................ 32 3.2.1.1 Modeling Domain .......................................................................... 32 3.2.1.2 Air Quality Model – WRF-Chem .................................................. 33 3.2.1.3 Generation of Erosion Factor Fields .............................................. 34 3.2.1.4 Prediction of PM10 and PM2.5 Values ............................................. 45 3.2.2 Modeling Calibration ..................................................................................... 45 4 RESULTS FOR THE SAN LUIS VALLEY-TAOS PLATEAU ........................................ 55 4.1 Construction Impacts Analysis .................................................................................. 55 4.1.1 Modeling Results ............................................................................................ 55 4.1.1.1 Antonito Southeast SEZ ................................................................. 55 4.1.1.2 De Tilla Gulch SEZ ........................................................................ 58 4.1.1.3 Los Mogotes East SEZ ................................................................... 60 4.1.2 Cumulative Impacts ........................................................................................ 61 4.2 Operations Impact Analysis ...................................................................................... 63 4.2.1 Scenarios Analyzed ........................................................................................ 63 4.2.2 Modeling Results For Development Scenarios .............................................. 64 4.2.3 Cumulative Impacts ........................................................................................ 72 4.2.4 Effectiveness of Dust Suppressants to Control Dust ...................................... 73 5 POTENTIAL HEALTH IMPACTS .................................................................................... 75 5.1 Health Impacts Associated with Particulate Matter .................................................. 75 5.1.1 Types of Effects ............................................................................................. 75 5.1.2 Comparison of PM Levels in the Study Area with Health-Based Standards ........................................................................................................ 76 5.2 Health Impacts Associated with Arsenic-Contaminated Particulate Matter ............. 80 iv Solar Development and Dust in San Luis Valley Study Area July 2016 TABLE OF CONTENTS (Cont.) 6 SUMMARY AND CONCLUSIONS .................................................................................. 85 6.1 Construction .............................................................................................................. 85 6.2 Operation ................................................................................................................... 85 6.3 Concluding Remarks ................................................................................................. 86 7 REFERENCES ..................................................................................................................... 89 LIST OF FIGURES ES.1-1 Locations of the San Luis Valley-Taos Plateau Study Area, Solar Energy Zones, and Nearby Federal Class I Areas .................................................................. ES-2 ES.2-1 Number of Days by Year and by Month with Monitored 24-Hour PM10 Concentrations Exceeding NAAQS of 150 µg/m3 at All Monitoring Sites Within the Study Area ................................................................................................ ES-8 ES.3-1 Distributions