SU0004094 - Laserfiche WebLink

Home Browse Search

4.6 Air Quality TABLE 4.6-6 OPERATIONAL DPM EMISSIONS (Tons Per Year)` Production Annual Risk Level Residency Concentration (persons per Significant? (million tons) (years) (Ng/m') million) Health Index (Yes/No) 4 70 0.073 22 0.0145 Yes 20 0.066 20 0.0131 Yes 2.85 70 0.061 18 0.0122 Yes 20 0.050 15 0.0099 Yes 1.7 70 0.049 15 0.0099 Yes 20 0.033 10 0.0065 No r SOURCE: Environmental Science Associates,2005. The maximum annual average DPM concentration(based on a residency time of 20 and 70 years for a facility operation of between 26 and 60 years)at these receptors was determined to be 0.073, 0.061, and 0.049 gg/m3, for the production rates of 4,2.85,and 1.7 million tons,respectively. Using the DPM unit risk factor, as established by OEHHA, the maximum incremental ` carcinogenic risk is estimated to be 22, 18, and 15 persons in a million, for the production rates of 4,2.85,and 1.7 million tons, respectively. This increment is greater than the significance threshold of 10 in a million (see Significance Criteria in the beginning of Section 4.63) for each r production rate. Therefore, the maximum carcinogenic health risks from DPM associated with the project would be significant. The maximum annual average concentrations are less than the non- carcinogenic AEL of 5 [Ig/M3,thus leading to a hazard index of less than the significance r. threshold of 1. Therefore, the non-carcinogenic risk from DPM would be less than significant. Based on an analysis of the census data$ for the area within two miles of the project, typical residency is no more than 20 years. By adjusting exposure to a 20 year residency, the maximum annual average DPM concentrations over that period and at the same receptors were estimated to be 0.066,0.050,and 0.033 gg/m3, for the production rates of 4, 2.85,and 1.7 million tons, respectively. Using the DPM unit risk factor, as established by OEHHA, the maximum incremental carcinogenic risk from a 20 year exposure would be 20, 15,and 10 persons in a million, for the production rates of 4, 2.85, and 1.7 million tons,respectively. These increments are greater than the significance threshold of 10 in a million. Therefore,the maximum carcinogenic health risks from DPM associated with the project would be significant. The maximum annual average concentrations are less than the non-carcinogenic AEL of 5 gg/m3, thus leading to a hazard index of less than the significance threshold of 1. Therefore, the non- carcinogenic risk from DPM would be less than significant.Additional information regarding the ` dispersion modeling and the health risk assessment is given in Appendix D. Although the modeling included both DPM emissions from onsite operations and from haul trucks, the greatest contributions to the total maximum risks are from onsite operations. These onsite operations are ■, not subject to CARB and federal EPA regulations that cover only on-road equipment. r B <http://factfinder.census.gov/servlet/MapItDrawServlet?geo_id=15000US060770055001&tree_id=403 &context—�t&_lmg==en&_ts=13925 2421476> RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.6-27 ESA/203015 Draft Environmental Impact Report May 2006