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Draft Supplemental Environmental Impact Report Page IV.D-23 Forward Inc. Landfill 2018 Revised Project Together with hydrocarbons,the second group is probably responsible for the background smell associated with a landfill. The sensory perception of odorants has four major dimensions: detectability,intensity, character, and hedonic tone. Odor detectability consists of a detection threshold and a recognition threshold.The detection threshold is the lowest concentration of an odorant that will elicit a sensory response in 50 percent of the population. There is an awareness of the presence of an added substance,but not necessarily an odor sensation. The detection thresholds are determined using human subjects and sophisticated dilution equipment. Detection thresholds are published for more than 900 chemicals. The recognition threshold is the minimum concentration that is recognized as having a characteristic odor quality by a segment of the population. Odor intensity refers to the perceived strength of the odor ' sensation, and odorant character is what the substance smells like (e.g.,fishy, rancid,hay, sewer,turpentine, ammonia,etc.). Garbage has been demonstrated to possess an odor with an unpleasant tone. Because offensive odors rarely cause any physical harm and no requirements for their control are included in state or federal air quality regulations,the SJVAPCD does not currently impose any rules or regulations that place quantifiable limitations on emissions of odorous substances, other than its Nuisance Rule 4102. Any actions related to odors are based on citizen complaints to local governments and the District. The SJVAPCD identifies a sanitary landfill as a type of facility that is a potential odor source. Because there are one or more sensitive receptors within the screening trigger distance of one mile from the landfill property,potential odor impacts from the Project must be considered.The District has established the following significance threshold for odor problems: • More than one confirmed complaint per year averaged over a three-year period, or • Three unconfirmed complaints per year averaged over a three-year period. Table IV.D-4: Project Net Criteria Pollutant Emissions (tons per year) Scenario NOx CO PM" PM,, Sox VOC Stationary Source Emissions(Requiring Offsets) Project(Flare)-Current Actual 29.0 115.9 19.7 19.7 12.5 6.6 ' Project(LFG Engines)-Current Actual 20.1 240.9 6.7 6.7 38.2 24.7 Project(Flare)-Current Permitted 4.9 1.7 4.1 4.1 3.1 1.6 Project(LFG Engines)-Current Permitted -4.0 126.7 -8.9 -8.9 28.9 19.7 Mobile Source Emissions Project-Current Actual(on-site equipment) 6.3 2.3 0.1 0.1 <0.1 0.9 Current Actual(off-site trucks) 36.0 4.7 0.9 0.9 0.1 1.2