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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 large. 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 Phase CO NOx PM10 PM2.5 <br />No Demolition 0.0 0.0 0.0 0.0 <br />No Site Preparation 0.0 0.0 0.0 0.0 <br />Grading 16.9 37.1 2.2 1.8 <br />Building 12.5 31.0 1.7 1.5 <br />Localized Significance Threshold 753.0 83.0 12.0 4 <br />Exceed Significance? NO NO NO NO <br />02/02/11 <br />10 <br />75B-118