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4. ENVIRONMENTAL ANALYSIS °a 4.7 GEOLOGY,SOILS,AND SEISNUCITY `. Liquefaction has been responsible for ground failures during almost all of California's large earthquakes. In the Central Valley of California,ground shaking has liquefied saturated sand and gravel deposits up to 50 feet below ground surface. When deep deposits of liquefiable soils fail, �► localized surface settlement can occur over time. Liquefaction is not considered an adverse geologic affect at the proposed project site because groundwater is over 100 feet deep and alluvial deposits underlying the site are unsaturated and consist of well distributed grain sizes varying from sand to gravel. Because the geologic conditions at the proposed project site are not conducive to liquefaction or the associated secondary ground failures, liquefaction is not discussed further in this chapter. Earthquake-Induced Settlement Settlement of the ground surface can be accelerated and accentuated by earthquakes. During an earthquake, settlement can occur as a result of the relatively rapid compaction and settling of subsurface materials(particularly loose,non-compacted, and variable sandy sediments)due to the rearrangement of soil particles during prolonged ground shaking. Settlement can occur both uniformly and differentially(i.e., where adjoining areas settle at different rates). Typically,areas underlain by artificial fills,unconsolidated alluvial sediments, and slope wash, and areas with improperly engineered construction fills are susceptible to this type of settlement.During an earthquake, some settlement of onsite soil materials may occur but because this is an active ` quarry and because engineered earthen structures (i.e.,berms,permanent slopes)would be compacted,hazards related to adverse affects of settlement are not anticipated and earthquake- induced settlement is not discussed further in this chapter. REGULATORYBACKGROUND Mine Safety and Health Administration Mine Safety and Health Administration (MSHA),a division of the U.S. Department of Labor, administers the provisions of the Federal Mine Safety and Health Act of 1977. MSHA develops and enforces mandatory safety and health regulations pursuant to the Code of Federal Regulations (CFR)30 that apply to all surface and underground mines located in the U.S.through inspections, rigorous training,and providing educational programs for employers and employees in the mining industry. The ultimate purpose is to eliminate fatal accidents,reduce the frequency and severity of nonfatal accidents,minitnize health hazards, and promote improved safety and health conditions in mines of the U.S. Project operations would be regulated by MSHA,and periodic inspections would be performed under MSHA regulations to ensure maximum worker safety during project operation. The proposed RMC Pacific Vernalis Quarry would be subject to periodic safety inspections by MSHA. SMARA and San Joaquin County SMARA, enacted by the California Legislature,addresses the need for continuous supplies of resources,acts to minimize adverse effects of mineral resource extraction operations,and encourages conservation and production of minerals while giving consideration to values relating T RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.7-11 ESA 1203015 Adminiwadw Draft ERR Manch 2004