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LLNL Emergency Management Plan (EPlan) Rev 27 January 2022 17 1.4.2.2 Topography and Geology Site 200, which is roughly one square mile, is located in the southeastern part of the Livermore valley within the eastern boundary of the City of Livermore. The valley is situated in a section of the California coast range that lies between San Francisco Bay on the west and the northern San Joaquin valley to the east. The Livermore valley is primarily of low relief, although it does contain scattered groups of hills that rise from 300 to 600 meters above the valley floor. Site 300 is located in the southeastern Altamont Hills of the Diablo range. The topography of Site 300 consists of a series of steep hills and canyons generally oriented northwest to southeast. The site is underlain by gently dipping sedimentary bedrock dissected by steep ravines. The bedrock consists of interbedded conglomerates, sandstones, siltstones, and claystones. The bedrock within Site 300 has been slightly deformed into several gentle, low-amplitude folds. The locations and characteristics of these folds, in combination with the regional fault and fracture patterns, locally influence groundwater flow within the site. Although LLNL’s Site 200 and Site 300 are somewhat removed from the largest and most active earthquake faults in California, both sites are located close to lesser active and potentially active faults. The most important of these are the Calaveras and Greenville faults. The Carnegie-Corral Hollow Fault system passes through Site 300 and 3 km east of Site 200. Additional information regarding earthquake potential is discussed in Section 1.4.2.5 below. 1.4.2.3 Population Distribution Following are population density data for areas in and around LLNL Sites 200 and 300, gathered from the U.S. Census Bureau and based on 2010 survey information: • Alameda County, CA, 1.5 million; 2,000 people per square mile • San Joaquin County, CA, 685,000; 493 people per square mile • Livermore, CA, population 81,000; 3,200 people per square mile • Tracy, CA, population 83,000; 3,745 people per square mile 1.4.2.4 Meteorology The climate at both sites is characterized by mild, rainy winters and warm-to-hot, dry summers, with strong seasonal wind and rainfall patterns. Wind patterns (see Figure 1.2) at both sites tend to be dominated by the thermal draw of the warm San Joaquin Valley that results in wind blowing from the cool ocean toward the warm valley during the warm season, increasing in intensity as the valley heats up. During the winter, the wind blows from the northeast more frequently as cold, dense air spills out of the San Joaquin Valley. The meteorological conditions at Site 300 are also strongly influenced by higher elevation and more pronounced topological relief. Approximately 55% of the rain at both sites falls in January, February, and March and approximately 80% falls in the five months from November through March, with very little rain falling during the warmer months.