SU0004094 - Laserfiche WebLink

Home Browse Search

4.Environmental Analysis — Existing Air Quality Conditions — A regional air quality monitoring network provides information on ambient concentrations of criteria air pollutants. Monitored ambient air pollutant concentrations reflect the number and strength of emissions sources and the influence of topographical and meteorological factors. — Table 4.6-3 presents a five-year summary of air pollutant data collected at the two representative monitoring stations nearest the project area;one in Modesto on 14'Street and one in Tracy,as well as the applicable State and Federal ambient air quality standards. The Modesto station, approximately 20 miles from the project, measures concentrations of all criteria air pollutants. The Tracy station, approximately 15 miles from the project, measures ozone concentrations only. — Pollutant concentrations measured at these stations should he representative of background air pollutant concentrations for the project area. Major sources of ROG emissions(a precursor to ozone formation) in the San Joaquin Valley are mobile sources, solvents,and oil and gas production. On-road motor vehicles and fuel combustion account for roughly 34 and 70 percent of the San Joaquin Valley's total ROG and — NOx emissions, respectively (CARB, 2003). Table 4.6-3 indicates that background PMto and ozone concentrations have exceeded state — standards in each year between 1997 and 2002. Major sources of PMIo in the region include motor vehicles,power generation, industrial processes, wood burning,construction and farming activities(CARB, 2003). Fugitive windblown dust also represents a significant source of airborne — dust. Exceedance of the CO standards is most likely to occur in winter months, when relatively low — inversion levels trap pollutants near the ground and concentrate the CO. Background CO concentrations in the vicinity of the Project site do not approach the state standards even during stagnant wintertime conditions. However, localized CO concentrations at congested intersections and freeway segments might be expected to be higher than the monitoring data,thereby creating local hot spots. The primary source of CO in the San Joaquin Valley is on-road motor vehicles, which account for approximately 68 percent of total CO emissions(CARB, 2003). Other sources include fireplaces, mobile sources(farm vehicles,trains, and ships)and waste burning(CARB, 2003). — Sensitive Receptors Land uses such as schools, hospitals, and convalescent homes are considered to be sensitive to — poor air quality conditions because infants,children, the elderly,and people with health afflictions(especially respiratory ailments) are more susceptible to respiratory infections and RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.6-14 ESA 1203015 Draft Environmental Impact Report May 2006