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Mitigated <br />51.6 <br />27.4 <br />1 31.6 <br />0.1 <br />4.7 <br />2.0 <br />SCAQMD Thresholds <br />75 <br />100 <br />550 <br />150 <br />150 <br />55 <br />Peak daily construction activity emissions are estimated be below SCAQMD CEQA thresholds <br />without the need for added mitigation. The only model -based mitigation measured applied for <br />this project was watering exposed dirt surfaces at least three times per day as required per <br />SCAQMD Rule 403 (Fugitive Dust), to minimize the generation of fugitive dust. <br />LOCALIZED SIGNIFICANCE THRESHOLDS <br />The SCAQMD has developed analysis parameters to evaluate ambient air quality on a local level <br />in addition to the more regional emissions -based thresholds of significance. These analysis <br />elements are called Localized Significance Thresholds (LSTs). LSTs were developed in <br />response to Governing Board's Environmental Justice Enhancement Initiative 1 -4 and the LST <br />methodology was provisionally adopted in October 2003 and formally approved by SCAQMD's <br />Mobile Source Committee in February 2005. <br />Use of an LST analysis for a project is optional. For the proposed project, the primary source of <br />possible LST impact would be during construction. LSTs are applicable for a sensitive receptor <br />where it is possible that an individual could remain for 24 hours such as a residence, hospital or <br />convalescent facility. <br />LST screening tables are available for 25, 50, 100, 200 and 500 meter source- receptor distances. <br />For this project the nearest sensitive use would be the residences southeast of the project site at <br />approximately 1200 feet from the closest site perimeter along Moir Court, and therefore, as a <br />conservative approach, the receptor distance of 200 meters was selected for analysis. <br />LSTs are only applicable to the following criteria pollutants: oxides of nitrogen (NOx), carbon <br />monoxide (CO), and particulate matter (PM -10 and PM -2.5). LSTs represent the maximum <br />emissions from a project that are not expected to cause or contribute to an exceedance of the <br />most stringent applicable federal or state ambient air quality standard, and are developed based <br />on the ambient concentrations of that pollutant for each source receptor area and distance to the <br />nearest sensitive receptor. <br />The SCAQMD has issued guidance on applying CaIEEMod to LSTs. LST pollutant screening <br />level concentration data is currently published for 1, 2 and 5 acre sites for varying distances. <br />Since CalEEMod calculates construction emissions based on the number of equipment hours and <br />the maximum daily soil disturbance activity possible for each piece of equipment, the following <br />tables should be used to determine the maximum daily disturbed- acreage for comparison to <br />LSTs. <br />Maximum Daily Disturbed Acreage <br />ni mnemt Type <br />Acres/8-hr-day <br />ractor <br />r <br />0.5 <br />raders <br />0,5 <br />rem e r S% np -6 <br />