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updated through 1999). The nearest known fault to the site,the Tracy-Stockton Fault Zone,passes through the City of Stockton, 6.5 miles northwest of the site. This fault zone is the closest known to the landfill and does not show evidence of Holocene displacement. The nearest active fault is the Great Valley 7 fault located approximately 19.8 miles(31.9km) southwest of the site. iThe seismic exposure of Forward Landfill was evaluated by GeoLogic Associates (2007). Since the Forward, Inc. Landfill is a Class II facility, the landfill design is based on the anticipated peak horizontal ground acceleration (PHGA) from a Probabilistic Seismic Hazard Assessment (PSHA) approach or the Maximum Credible Earthquake (MCE). Therefore, GLA proposed the MCE magnitude of 6.7 on the Great Valley 7 fault as a design-level earthquake. Using this magnitude, GLA used a variety of attenuation relationships from Blake (2004a) to evaluate the PHGA at the site. The attenuation relationship by Campbell and Bozorgnia (1994, revised 1997) for alluvial sites assuming a reverse fault event was concluded to be the most appropriate for the site conditions. Using this attenuation relationship, a PHGA of 0.13g was calculated for the MCE event of 6.7 on the Great Valley 7 fault at a distance of 19.8 miles (31.9 km). However, the family of attenuation curves for reverse faulting (Ord6nez, 2006; SHAKE 2000) indicates an upper bound horizontal ground acceleration of 0.15g. 3.6 Air Quality Forward Landfill lies within the San Joaquin Valley Air Basin (SJVAB), a relatively topographically broad, flat area (250 miles long and 35 miles wide) bordered on the east by the Sierra Nevada Mountains; on the west by the Coast Ranges; and to the south by the Tehachapi Mountains. Airflow in the SJVAB is primarily influenced by marine air that enters through the Carquinez Straits where the San Joaquin-Sacramento Delta empties into the San Francisco Bay. The region's topographic features restrict air movement through and out of the basin. As a result, the SJVAB is highly susceptible to pollutant accumulation over time. Frequent transport of air pollutants into the SJVAB from upwind sources also negatively contributes to air quality. Wind speed and direction play an important role in dispersion and transport of air pollutants. During summer periods, winds usually originate from the north end of the San Joaquin Valley and flow in a south-southeasterly direction through the valley, through the Tehachapi pass and into the neighboring Southeast Desert Air Basin. During winter months, winds occasionally originate from the south end of the valley and flow in a north-northwesterly direction. Also, during winter months, the valley experiences light, variable winds, less than 10 miles per hour ' (mph). Low wind speeds, combined with low inversion layers in the winter, create a climate conducive to high concentrations of certain air pollutants. The SJVAB has an inland Mediterranean climate that is characterized by warm, dry summers and cool winters. Summer high temperatures often exceed 100 degrees Fahrenheit (°F), averaging from the low 90s in the northern part of the valley to the high 90s in the south. The daily summer temperature variation can be as high as 30°F. Winters are for the most part mild and humid. Average high temperatures during the winter are in the 50s, while the average daily C:ubcommts md Settingsyasicasees\Desktoffonvard LFGI'E-Pmject Description.doc CORNERSTONE 3-5 o.o n,ace LEWIS ENGINEERING