COMPLIANCE INFO_FINAL INITIAL STUDY/MITIGATED NEGATIVE DECLARATION 5/25

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Memorandum March 25, 2025 Page 2 21202-23 North County Landfill_AQ_0307 add one more hour to the Noth County Landfill’s daily operations between 6:00 am and 7:00 am to allow the acceptance of commercial waste during this time period. The project would not change the North County Landfill’s capacity and would not involve new construction. At current operational levels, the projected closure year of the landfill is 2046. With the implementation of the project, the projected closure date would move up three years to 2043. In 2006, the North County Landfill installed a landfill gas (LFG) collection system, including a flare, vertical wells, and connecting piping. Additional LFG collectors, primarily horizontal collection trenches, will continue to be installed in the refuse and connected to the LFG collection system as the landfill is constructed. Collected LFG is combusted in a temperature- controlled flare in accordance with the existing San Joaquin Valley Air Pollution Control District (Valley Air District) Title V permit (N-119-1-13). A new 1,200 standard cubic feet per minute low nitrogen oxides (NOx) flare was installed in October 2024 and is currently used as the primary flare. The previous flare will be used as back-up. ENVIRONMENTAL SETTING Regional Climate, Meteorology, and Topography The project site is located within the San Joaquin Valley Air Basin (SJVAB). The SJVAB encompasses eight counties, including Fresno, Kern (western and central), Kings, Madera, Merced, San Joaquin, Stanislaus, and Tulare. Air basins have characteristics that limit the ability of natural processes to either dilute or transport air pollutants. The major determinants of air pollution transport and dilution are climatic and topographic factors such as wind, atmospheric stability, terrain that influences air movement, and sunshine. Wind and terrain can combine to transport pollutants away from upwind areas, while solar energy can chemically transform pollutants in the air to create secondary photochemical pollutants such as ozone. The San Joaquin Valley (Valley) is bordered by the Sierra Nevada Mountains in the east, the Coast Ranges in the west, and the Tehachapi mountains in the south. The surrounding mountains created a bowl-shaped topography, limiting movement of pollutants out of the Valley. The Valley has a mediterranean climate characterized by wet winters with sparse rainfall, and hot and dry summers. In addition, persistent temperature inversions occur in the Valley, preventing vertical dilution of pollutants and increase the concentrations of pollutants at or near the ground. Summertime high temperatures in the Valley often exceed 100 degrees Fahrenheit, while wintertime high-pressure events drop the temperature into the 30s degrees Fahrenheit. During summer, prevailing winds primarily originate from the northwest, directing the airflow toward the southwestern end of the Valley. Additionally, a notable secondary wind pattern comes from the southeast, attributable to nighttime drainage winds, prefrontal conditions, and summer monsoons. During winter, stagnant conditions characterized by very weak winds often occur between storms. The high-pressure and light winds allow cold moist air to accumulate on the San Joaquin Valley floor, contributing to the formation of Tule fog. The