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MacArthur Project Modification — Santa Ana - Air Quality Assessment <br />KPC Environmental, Inc. <br />4.3.2 Sensitive Receptors & SCAQMD LST's <br />When considering land uses and population densities in their jurisdiction, local public <br />agencies should be aware of land use compatibility issues, particularly in reference to <br />sensitive receptors. A sensitive receptor is a person in the population who is particularly <br />susceptible to health effects due to exposure to an air contaminant than is the population <br />at lame. Sensitive receptors and associated facilities that house them in proximity to local <br />CO sources, toxic air contaminants or odors are of particular concern. <br />Sensitive receptors include the very young, elderly, and persons suffering from illness are <br />normally associated with locations such as schools, day -car facilities, convalescent care <br />facilities, medical facilities, and residential areas. Sensitive receptors located in the vicinity <br />of the proposed project site include the residential areas surrounding the project site. <br />Evaluations according to SCAQMD recommendations need to be conducted to ensure that <br />sensitive receptors will not be exposed to localized concentrations of the criteria pollutant <br />carbon monoxide (CO). High levels of CO are associated with traffic congestion in <br />particular slow- moving and idling vehicles. Depending on the existing background <br />concentrations of CO, roadways have the potential to be CO hot spots. Therefore projects <br />with sensitive receptors or projects that could negatively impact levels of service (LOS) <br />should utilize the Emfac 2007 v. 2.3 and CALINE 4 programs to evaluate the effects of <br />vehicle emissions to determine if the project will cause the state 1 -hour or 8 -hour CO <br />standards to be exceeded, creating a "CO hotspot." <br />As part of the review for potential impacts on Sensitive Receptors the SCAQMD has been <br />requesting that all projects less than 5 -acres in size complete the Localized Significance <br />Threshold (LST) Analysis. <br />The LST's were run for the project as shown in Table 4 -6 and indicate that no LST's are <br />estimated to be exceeded during the construction of the project. The LST's were conducted <br />for Mass Grading/Excavation and Construction with defaults or modified to compare with <br />URBEMIS emissions as appropriate. The receptor distance was selected at 50 meters on a <br />1 -acre site. <br />Table 4 -5 LST Results <br />Construction 1'b _ <br />'Co <br />NOx <br />1'M10 <br />PM2.5 <br />No Demolition <br />0.0 <br />0.0 <br />0.0 <br />0.0 <br />No Site Preparation <br />0.0 <br />0.0 <br />0.0 <br />0.0 <br />Grading <br />16.9 <br />37.1 <br />2.2 <br />1.8 <br />Building <br />12.5 <br />31.0 <br />1.7 <br />1.5 <br />Localized Significance Threshold <br />753.0 <br />83.0 <br />12.0 <br />4 <br />Exceed Si nificancc? <br />NO <br />NO <br />NO <br />NO <br />02/02/11 10 <br />