3.7 GEOLOGY, SOILS, AND SEISMICITY

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1 Geology, Soils, and Seismicity 3.7 GEOLOGY, SOILS, AND SEISMICITY This section describes the existing geology, soils, and paleontological and mineral resources at and in the vicinity of the plan area and analyzes the potential physical environmental effects of the 2018 LRDP related to these topics. For information on soil quality related to agricultural use, refer to Section 3.2, Agriculture and Forestry Resources. For information related to flooding, drainage, and groundwater quality at the plan area, refer to Section 3.10, Hydrology and Water Quality, of this EIR. Public comments on the NOP included concerns regarding erosion. These impacts are described and addressed within this section Regulatory Setting FEDERAL National Earthquake Hazards Reduction Act The National Earthquake Hazards Reduction Act was passed to reduce the risks to life and property resulting from earthquakes. The act established the National Earthquake Hazards Reduction Program (NEHRP). The mission of NEHRP includes improved understanding, characterization, and prediction of hazards and vulnerabilities; improved building codes and land use practices; risk reduction through post-earthquake investigations and education; development and improvement of design and construction techniques; improved mitigation capacity; and accelerated application of research results. NEHRP designates the Federal Emergency Management Agency as the lead agency of the program and assigns several planning, coordinating, and reporting responsibilities. Other NEHRP agencies include the National Institute of Standards and Technology, National Science Foundation, and the U.S. Geological Survey (USGS). STATE Alquist-Priolo Earthquake Fault Zoning Act The Alquist-Priolo Earthquake Fault Zoning Act of 1972 (Alquist-Priolo Act) (Public Resources Code [PRC] Section ) intends to reduce the risk to life and property from surface fault rupture during earthquakes by regulating construction in active fault corridors and prohibiting the location of most types of structures intended for human occupancy across the traces of active faults. The law addresses only the hazard of surface fault rupture and is not directed toward other earthquake hazards. Seismic Hazards Mapping Act The intention of the Seismic Hazards Mapping Act of 1990 (PRC Section ) is to reduce damage resulting from earthquakes. While the Alquist-Priolo Act addresses surface fault rupture, the Seismic Hazards Mapping Act addresses other earthquake-related hazards, including ground shaking, liquefaction, and seismically induced landslides. The act s provisions are similar in concept to those of the Alquist-Priolo Act: The State is charged with identifying and mapping areas at risk of strong ground shaking, liquefaction, landslides, and other corollary hazards, and cities and counties are required to regulate development within mapped Seismic Hazard Zones. Under the Seismic Hazards Mapping Act, permit review is the primary mechanism for local regulation of development Long Range Development Plan EIR 3.7-1

2 Geology, Soils, and Seismicity Specifically, cities and counties are prohibited from issuing development permits for projects in Seismic Hazard Zones until appropriate site- specific geologic or geotechnical investigations have been carried out and measures to reduce potential damage have been incorporated into the development plans. California Building Standards Code The State of California provides minimum standards for building design through the California Building Standards Code (CBC) (California Code of Regulations, Title 24). Where no other building codes apply, Chapter 29 regulates excavation, foundations, and retaining walls. The state earthquake protection law (California Health and Safety Code Section et seq.) requires that structures be designed to resist stresses produced by lateral forces caused by wind and earthquakes. The CBC has been modified from the International Building Code for California conditions with more detailed and/or more stringent regulations. The CBC identifies seismic factors that must be considered in structural design. Specific minimum seismic safety and structural design requirements are set forth in Chapter 16 of the CBC. Chapter 18 of the CBC regulates the excavation of foundations and retaining walls, while Chapter 18A regulates construction on unstable soils, such as expansive soils and areas subject to liquefaction. Appendix J of the CBC regulates grading activities, including drainage and erosion control. The CBC also contains a provision that provides for a preliminary soil report to be prepared to identify the presence of critically expansive soils or other soil problems which, if not corrected, would lead to structural defects (CBC Chapter ). Surface Mining and Reclamation Act of 1975 The Surface Mining and Reclamation Act of 1975 (PRC Sections ) provides for the classification of non-fuel mineral resources in the state to show where economically significant mineral resources occur or are likely to occur. Classification is carried out under the Mineral Land Classification Project under the direction of the State Geologist. Once lands have been classified, they may be designated by the State Mining and Geology Board as mineral-bearing areas of statewide or regional significance if they are in areas where urban expansion or other irreversible land uses may occur that could restrict or preclude future mineral extraction. Designation is intended to prevent future land use conflicts, and occurs only after consultation with lead agencies and other stakeholders. The California Department of Conservation, Division of Mines and Geology has developed guidelines for the classification and designation of mineral lands. These guidelines contain information on what are known as Mineral Resource Zones (MRZs), which together comprise a system of classifying lands based on their economic importance (California Department of Conservation 1988). The MRZ system consists of four categories into which lands may be classified based on the degree of available knowledge about the resource, and the level of economic significance of the resource. These zones are described as follows. MRZ-1: Areas where adequate information indicates that no significant mineral deposits are present, or where it is judged that little likelihood exists for their presence. MRZ-2: Areas where adequate information indicates that significant mineral deposits are present, or where it is judged that a high likelihood exists for their presence. MRZ-3: Areas containing mineral deposits for which the significance cannot be determined from available data. MRZ-4: Areas where available information is inadequate for assignment of any other MRZ category Long Range Development Plan EIR

3 Geology, Soils, and Seismicity Assembly Bill 885 AB 885 amended California Water Code section 13290, which required the State Water Resources Control Board (SWRCB) to develop statewide standards for permitting and operation of Onsite Wastewater Treatment Systems, septic systems. The SWRCB adopted the Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Systems which became effective on May 13, This policy established a statewide risk-based tiered approach for the regulation and management of Onsite Wastewater Treatment Systems. UNIVERSITY OF CALIFORNIA University of California Seismic Safety Policy The University of California Seismic Safety Policy was crafted to provide an acceptable level of earthquake safety for students, employees, and the public who occupy university facilities and leased facilities, to the extent feasible by present earthquake engineering practice. Feasibility is determined by balancing the practicality and the cost of protective measures, depending on the forecasted severity and probability of injury resulting from seismic activity. Environmental Health and Safety The Environmental Health and Safety (EHS) provides programs and leadership on campus safety topics including natural and man-made disaster preparedness, fire prevention, personal and workplace safety, and risk management for campus research and other activities. LOCAL As noted in Section 3.0.2, University of California Autonomy,, a constitutionally created State entity, is not subject to municipal regulations of surrounding local governments for uses on property owned or controlled by that are in furtherance of the university s education purposes. However, may consider, for coordination purposes, aspects of local plans and policies for the communities surrounding the campus when it is appropriate and feasible, but it is not bound by those plans and policies in its planning efforts. Yolo County Code Yolo County Code Section requires a Sewage Disposal Permit for the construction, reconstruction, repair, or abandonment of a septic system. The Yolo County Department of Health (YCDH) issues permits for installation of septic systems in Yolo County and provides guidelines, which those installing the systems must follow. Solano County Code Chapter 6.4, Sewage Standards, of the Solano County Code includes regulations governing on-site sewage disposal systems and permitting. The Environmental Health Services, a division of the Solano County Department of Resource Management, issues permits for installation of septic systems in Solano County and provides guidelines, which those installing the systems must follow Long Range Development Plan EIR 3.7-3

4 Geology, Soils, and Seismicity Environmental Setting REGIONAL GEOLOGY The is located within the Great Valley geomorphic province, which is a river outwash plain roughly 50 miles wide and 400 miles long, bordered by the Coast Range in the west and the Sierra Nevada range in the east. The Great Valley encompasses the Sacramento and San Joaquin valleys and their respective rivers, which join and enter the San Francisco Bay. In Jurassic and Cretaceous times, the Great Valley was a deep water inland arm of the Pacific Ocean. Over time, the valley was filled in first by fine textured marine sediments, followed by river and flood (alluvial) deposits. Because the bedrock of the Great Valley is tilted, sloping downward from east to west, the deepest areas of marine and alluvial deposits are found along the eastern edge of the Coast Range. The plan area is located at the southwestern end of the Sacramento Valley, approximately 30 miles north of the confluence of the San Joaquin and Sacramento rivers. SOILS The plan area is underlain by Quaternary (present time to 1.6 million years ago) alluvial deposits. The Natural Resources Conservation Service (NRCS) Soil Survey of the plan area (NRCS 2015) indicates that there are 10 different soil mapping units (four major and nine minor) occurring within the plan area. Refer to Exhibit for soil map unit boundaries. The descriptions below represent general characteristics of these soil series; specific characteristics of soil units located within the plan area are identified where appropriate. While there are a wide array of soil parameters and characteristics, only those that are pertinent to assessing project impacts are described below, including source material, geographic setting, drainage characteristics, permeability, and the risk of erosion and soil expansion. Major campus soil components (>10 percent dominant component by area): Yolo Series (Y): Yolo series soils are formed in fine, loamy alluvium derived from sedimentary sources, and can be found on nearly level to moderately sloping alluvial fans. These soils are widespread throughout the plan area, composed of predominantly well-drained loam, with varying amounts of silt and/or clay. These soils are generally well-drained, exhibit moderate permeability, slow-to-medium surface water runoff, low soil erosion hazard, and moderate shrinkswell potential. Tillage pans have developed over broad areas of this soil type that tend to restrict permeability. Reiff Series (Re): Reiff series soils are formed in weathered material from mixed sources. They are found on nearly level to moderately sloping floodplains or alluvial plains, at elevations of 30 to 500 feet above sea level (asl). These soils are well drained and exhibit moderately rapid permeability, very slow to slow runoff, and minimal hazard of erosion. Within the plan area, shrink-swell potential is low. Reiff soils are found on approximately 26 percent of campus lands, on the west, central, and south campuses. Sycamore Series (S): Sycamore series soils formed from mixed sedimentary alluvium under poorly drained conditions, and can be found on nearly level flood plains at low elevations (10 to 100 asl). Within the plan area, these soils are well drained and comprised of silt loam and silty clay loam. Soil characteristics include: moderately slow permeability and slow surface water runoff, and low erosion hazard. There is low to moderate shrink-swell potential for these soils within the plan area. Sycamore soils are found on the west and central campuses. Myers Series (M): Myers series soils formed in sedimentary alluvium, and are found on flat alluvial fans at elevations ranging between 25 and 2,000 feet asl. They are well to moderately well drained, and exhibit slow permeability, slow runoff, minimal erosion hazard, and high shrinkswell potential Long Range Development Plan EIR

5 Geology, Soils, and Seismicity Exhibit 3.7-1: Soils in the Plan Area 2018 Long Range Development Plan EIR 3.7-5

6 Geology, Soils, and Seismicity Minor campus soil components (<10 percent dominant component by area): Brentwood Series: Brentwood series soils are formed in valley fill eroded from sedimentary sources, and are found on nearly level to gently sloping alluvial fans at elevations of 40 to 400 feet asl. They are well to moderately well drained, exhibit moderately slow permeability, very slow to medium runoff, minimal erosion hazard, and high shrink-swell potential. Capay Series: Capay soils are formed in fine alluvium derived from sandstone, shale, or other mixed rock sources. They are found on alluvial fans, alluvial flats, and on interfan basins at elevations below 1,200 feet asl. They exhibit slow to very slow permeability, and a high range of runoff potential from very low to high, minimal hazard of erosion, and high shrink-swell potential. Corning Series: Corning series soils are located on nearly level to gently rolling high terraces and terrace remnants, and terrace sideslopes at elevations of 75 to 1,300 feet asl. They formed in gravelly alluvium derived from mixed rock sources and exhibit slow to very slow permeability, moderate erosion hazard, and high shrink-swell potential. Hillgate Series: Hillgate series soils are located on nearly level to moderately sloping old terraces at elevations ranging from 15 to 2,000 feet asl. The soils are formed in alluvium from mixed rock sources. These soils are moderately well drained and have a wide range in surface water runoff conditions and slow to very slow permeability, and a slight to moderate erosion hazard. Myers Series: Myers series soils formed in sedimentary alluvium, and are found on flat alluvial fans at elevations ranging between 25 and 2,000 feet. They are well to moderately well drained, and exhibit slow permeability, slow runoff, minimal erosion hazard, and high shrink-swell potential. Slow percolation places severe limitations affecting septic tank absorption fields. These soils are found on Russell Ranch. Rincon Series: Rincon series soils are found on older alluvial fans and stream and marine terraces, at elevations ranging between 20 and 2,000 feet asl. These soils are well drained, exhibit slow permeability, very slow runoff, minimal erosion hazard, and moderate to high shrinkswell potential. These soils are found locally on the west campus, and on Russell Ranch. Zamora Series: Zamora series soils are found on nearly level to strongly sloping alluvial fans and terraces (generally 0-9 percent slopes), at elevations between 30 and 1,300 feet asl. They exhibit moderately slow permeability, slow to medium runoff, and minimal erosion hazard. Within the plan area, Zamora series soils represent moderate shrink-swell hazard. Loamy Alluvial Land: Loamy alluvial land is a landcover type that consists of highly variable loam soils that are not practical to classify into separate units. Generally, these soils are nearly level, formed in mixed, stratified alluvium deposited adjacent to streams, and are found at elevations of 25 to 400 feet asl. Their texture is characterized by sand, sandy loam, loam, and silt loam, and they are underlain by sand and gravel deposits. They are well drained, exhibit rapid permeability and little to no erosion hazard. Only local pods of these soils are present in the plan area, exhibiting a range of shrink-swell potential, from low to high. Riverwash: Riverwash is excessively drained, sandy, gravelly, or stony stream deposits. It exhibits very rapid permeability, very slow runoff when not flooded, and is subject to scouring and deposition. Riverwash is found in and alongside the Putah Creek channel. PALEONTOLOGICAL SETTING Significant nonrenewable vertebrate and invertebrate fossils and unique geologic units have been documented throughout California. The fossil yielding potential of a particular area is highly dependent on the geologic age and origin of the underlying rocks (refer to geologic timescale in Table 3.7-1). Paleontological potential refers to the likelihood that a rock unit will yield a unique or significant paleontological resource. All sedimentary rocks, some volcanic rocks, and some low-grade metamorphic rocks have potential to yield significant paleontological resources. Depending on Long Range Development Plan EIR

7 Geology, Soils, and Seismicity location, the paleontological potential of subsurface materials generally increases with depth beneath the surface, as well as with proximity to known fossiliferous deposits. Table Divisions of Geologic Time Era Period Time in Millions of Years Ago (approximately) Epoch Quaternary < 0.01 Holocene 2.6 Pleistocene 5.3 Pliocene Cenozoic 23 Miocene Tertiary 34 Oligocene 56 Eocene 65 Paleocene Cretaceous Mesozoic Jurassic Triassic Permian Carboniferous Paleozoic Devonian Silurian Ordovician Cambrian Precambrian 2,500 - Source: USGS 2010 Pleistocene or older (older than 11,000 years) continental sedimentary deposits are considered as having a high paleontological potential while Holocene-age deposits (less than 10,000 years old) are generally considered to have a low paleontological potential because they are geologically immature and are unlikely to have fossilized the remains of organisms. Metamorphic and igneous rocks have a low paleontological potential, either because they formed beneath the surface of the earth (such as granite), or because they have been altered under high heat and pressures, chaotically mixed or severely fractured. Generally, the processes that form igneous and metamorphic rocks are too destructive to preserve identifiable fossil remains. The plan area is located at the southwestern end of the Sacramento Valley within the Great Valley Geomorphic Province. The Great Valley Province is a long, narrow northwest-trending alluvial valley that lies between the Sierra Nevada Range to the east and the Coast Ranges to the west. The Sacramento Valley is located in the northern portion of the Great Valley and is bounded by the Klamath Mountains to the north and the Stockton Arch to the south. This region formed as a forearc basin during the subduction of the Pacific plate underneath the North American plate. Valley sediments range from Jurassic to Holocene in age and record a history of alternating marine and terrestrial depositional environments. The Sacramento Valley has been filled over time with up to a 6-mile thick sequence of interbedded clay, silt, sand, and gravel deposits. The sediments range in age from more than 144 million years old (Jurassic Period) to less than 10,000 years (Holocene). The most recent sediments consist of coarse-grained (sand and gravel) deposits along river courses and fine grained (clay and silt) deposits located in low lying areas or flood basins and are referred to as alluvial deposits. These 2018 Long Range Development Plan EIR 3.7-7

8 Geology, Soils, and Seismicity deposits are loose and not well consolidated soils. The plan area is underlain by is underlain by quaternary alluvium from the Holocene period. SEISMICITY The state of California contains many significant, active faults, and is highly susceptible to earthquakes, and therefore is predisposed to earthquake hazards. California has addressed these hazards to public safety and property through identification and regulations. Zones of required investigation for possible earthquake faulting, landslides, and liquefaction are delineated and distributed to cities, counties, and state construction agencies to help identify where higher building standards may be necessary for safe development. Seismic hazards resulting from earthquakes include ground rupture along a fault line (also called surface rupture) ground shaking, liquefaction, subsidence, and mass wasting. Each of these potential hazards is discussed below. Faults Most earthquakes originate along fault lines. A fault is a fracture in the Earth s crust along which rocks on one side are displaced relative to those on the other side due to shear and compressive crustal stresses. Most faults are the result of repeated displacement that may have taken place suddenly and/or by slow creep (Bryant and Hart 2007: p. 3). The state of California has a classification system that designates faults as either active, potentially active, or inactive depending on how recently displacement has occurred along them. Faults that show evidence of movement within the last 11,000 years (the Holocene geologic period) are considered active, and faults that have moved between 11,000 and 1.6 million years ago (comprising the later Pleistocene geologic period) are considered potentially active. Faults that have not demonstrated movement within the last 1.6 million years are classified as inactive. The known active faults (faults that have produced surface displacement within the past 11,000 years) closest to the campus are the Dunnigan Hills Fault (approximately 16.5 miles north of campus), the Cordelia Fault Zone (approximately 27 miles southwest), and the Green Valley Fault (approximately 28 miles southwest). The Cordelia Fault Zone and the Green Valley Fault represent the easternmost reach of the San Andreas Fault Zone, the central line of which is located approximately 67 miles to the southwest. The campus is not located within an Alquist-Priolo Fault Zone as defined in the Alquist-Priolo Earthquake Fault Zoning Act, which is designed to prohibit the construction of structures for human occupancy across active faults. The campus is also not located within an area mapped pursuant to the Seismic Hazards Mapping Act. Table lists some of the active and potentially active faults in relatively close proximity to the plan area. Table Active and Potentially-active Nearby Faults Fault or Fault Zone Distance from Plan Area Status Dunnigan Hills Fault 16.5 miles north Active Vaca Fault Zone 18.5 miles southwest Potentially Active Putah Creek Fault 21 miles west Potentially Active Cordelia Fault Zone 27 miles southwest Active Green Valley Fault 28 miles southwest Active Bear Mountains Fault Zone 45 miles east Potentially Active Bennett Valley Fault Zone 49 miles west-southwest Potentially Active San Andreas Fault Zone 69 miles west-southwest Active Source: Bryant Long Range Development Plan EIR

9 Geology, Soils, and Seismicity The 1994 Fault Map of California shows the East Valley fault approximately beneath the Russell Ranch portion of the campus (Jennings 1994). The fault is subsurface and its location is inferred, as it has not created any surface rupture. It is believed that the last movement along this fault occurred over 1.6 million years ago, and the fault is generally considered inactive (Harwood and Helley 1987). Because the East Valley Fault does not exhibit a surface expression, the date of the last movement along the fault is a general estimate. This fault is located deep beneath the ground surface, and although there is a remote possibility that it could be the source of earthquakes and associated ground shaking, it would not cause ground surface rupture. Seismic History Numerous earthquakes have been felt on campus (major earthquakes occurred in 1892, 1906, and 1989). The greatest historical seismic event felt in the plan area occurred in 1892, with the epicenter located along an unnamed fault in the vicinity of the English Hills between Winters and Vacaville. Available newspaper reports from the Davis vicinity reported that damage included fallen chimneys and cracked walls (Cowen et al. 1992). PRIMARY SEISMIC HAZARDS Ground Shaking The magnitude of ground shaking due to an earthquake is typically presented as a percentage of the acceleration due to gravity ( g ). The peak ground acceleration (PGA), expressed as g, represents the maximum ground acceleration (or motion) measured during an earthquake at a given location, and is expressed as the probability of exceedance. It accounts for composition of ground materials, among other factors. This variability in factors can account for a large difference in PGA over short distances and can produce very different predictions for ground motion in locations that are close together, even with earthquakes of the same or similar magnitude. This makes the PGA a good tool for engineers and planners, because it is a prediction of the expected ground motion in an area and can be used to anticipate the seismic risk in an area, and the level of engineering required to protect structures and people. According to the California Geological Survey s Probabilistic Seismic Hazard Assessment for the State of California, the peak ground acceleration with a 2 percent probability of being exceeded in 50 years, for the central, west, and south campus areas is estimated to be approximately g, and closer to 0.6g on the western portion of campus at Russell Ranch. This level of seismic motion has the potential to produce moderate to heavy damage, by dislodging objects from shelves and damaging or destroying buildings and other structures (DOC 2008). By way of comparison, most parts of the San Francisco Bay Area have a peak ground acceleration of 0.8g or greater. Likely effects of ground shaking during a probable maximum intensity earthquake for the area could include structural damage to stucco, masonry walls, and chimneys, which could expose people to risks associated with falling objects and potential building collapse. The extent of these effects would be determined by the specific nature of underlying soil and rock materials, the structural characteristics and materials of affected buildings, the location of the epicenter and magnitude of the earthquake, and the duration of the ground motion. The intensity of seismic shaking, or strength of ground motion, during an earthquake is dependent on the distance and direction from the epicenter of the earthquake, the magnitude of the earthquake, and the geologic conditions of the surrounding area. Ground shaking could potentially result in the damage or collapse of buildings and other structures. The plan area is in an area mapped as likely to experience high-intensity shaking during an earthquake, with a Modified Mercalli Intensity (MMI) of 7 (ABAG 2015). In contrast to the PGA, the MMI scale estimates the intensity of 2018 Long Range Development Plan EIR 3.7-9

10 Geology, Soils, and Seismicity shaking from an earthquake at a specific location by considering its perceived effects on people, objects, and buildings. At MMI 7, perceived shaking would be severe. SECONDARY SEISMIC HAZARDS Liquefaction and Lateral Spreading Liquefaction is a phenomenon in which loose, saturated, granular soil deposits lose a significant portion of their shear strength because of excess pore water pressure buildup. Cyclic loading, such as an earthquake, typically causes the increase in pore water pressure and subsequent liquefaction. These soils are liquefied during seismic shaking and re-solidify when shaking stops. The potential for liquefaction is highest in areas with high groundwater and loose, fine, sandy soils at depths of less than 50 feet. Liquefaction may also lead to lateral spreading. Lateral spreading (expansion) is the horizontal movement or spreading of soil toward an open face, such as a streambank, the open side of fill embankments, or the sides of levees. It often occurs in response to liquefaction of soils in an adjacent area. The potential for failure from lateral spreading is highest in areas where there is a high groundwater table, where there are relatively soft and recent alluvial deposits, and where creek banks are relatively high. There are no streams within the plan area; however, because it is anticipated that there is a moderate potential for liquefaction of soil at the site, the potential for lateral spreading to occur should also be considered moderate. Soils deposited in the region typically consist of loose alluvial deposits that could be susceptible to liquefaction and settlement. Liquefaction is a quicksand-type ground failure caused by ground shaking that is most likely to occur in low-lying areas of poorly consolidated, water-saturated sediments or similar deposits of artificial fill. Because of the generally low groundwater levels on the campus, liquefaction is unlikely. Settlement is the compaction of soil and alluvium caused by static loads (such as foundations for structures) or by ground shaking effects such as liquefaction. Due to the presence of compressible clay soils on campus, settlement has been identified as a building constraint in some areas on campus. However, building design (including shallow foundations and pier foundations) and replacement of soils under foundations with engineered fill can reduce the extent of settlement (Kleinfelder 1998; Wallace Kuhl Associates 1999 and 2002). Localized soil assessments will continue to be prepared for campus construction projects under the 2018 LRDP to identify any site-specific potential for secondary seismic effects like liquefaction and settlement. OTHER GEOLOGIC HAZARDS Expansive Soils Expansive soils (also known as shrink-swell soils) are soils that contain expansive clay minerals that can absorb significant amounts of water into their crystalline structure. The presence of these clay minerals makes the soil prone to large changes in volume in response to changes in water content. The quantity and type of expansive clay minerals affects the potential for the soil to expand or contract. When an expansive soil becomes wet, water is absorbed and it increases in volume, and as the soil dries it contracts and decreases in volume. This (often repeated) change in volume can produce enough force and stress on buildings and other structures to damage foundations and walls. One measure of the shrink-swell potential of soils is linear extensibility. Linear extensibility refers to the change in length of an unconfined clod as moisture content is decreased from a moist to a dry state. The volume change is reported as percent change for the whole soil. The amount and type of clay minerals in the soil influence volume change. The shrink-swell potential is low if the soil has a Long Range Development Plan EIR

11 Geology, Soils, and Seismicity linear extensibility of less than 3 percent, moderate if 3 to 6 percent, high if 6 to 9 percent, and very high if more than 9 percent. The NRCS has prescribed linear extensibility ratings to most soil series in California. As shown in Exhibit soils in the plan area exhibit a range in linear extensibility from low to high (NRCS 2015). Erosion Erosion is the process by which soil and rock at the earth s surface is gradually broken down and transported to a different location. Erosive processes include rainfall, surface runoff, glacial activity, wind abrasion, chemical dissolution, and gravity in the form of mass wasting. Under normal conditions, these erosive processes control the rate at which erosion occurs, together with physical characteristics of the material being eroded. Anthropogenic activities can accelerate that rate, causing excessive erosion and a wide variety of detrimental effects on the environment including sedimentation of waterways, eutrophication of water bodies, slope instability, ground instability, loss of agricultural productivity through the removal of topsoil, or even desertification. The primary erosive forces present within the plan area are water and wind erosion. Erosion has a detrimental effect on soil productivity because erosion begins with the upper horizons of a soil profile, which contain organic matter and microbial communities vital to supporting plant growth. Factors that influence the erosion potential of a soil include: vegetative cover; soil properties such as soil texture, structure, rock fragments and depth; steepness and slope length; and climatic factors such as the amount and intensity of precipitation. The NRCS soil surveys provide an erosion hazard rating. This rating is based on slope and soil erosion factor (K). The predicted soil loss is caused by sheet or rill erosion (which happens when shallow flows of water causing sheet erosion are concentrated into rills and increase both in speed and scouring capacity) areas where 50 to 75 percent of the surface has been exposed by disturbance. The hazard is described as slight, moderate, severe, or very severe. A rating of slight indicates that erosion is unlikely under ordinary conditions; moderate indicates that some erosion is likely and that erosion-control measures may be needed; severe indicates that erosion is very likely and that erosion-control measures, including revegetation of bare areas, are advised; and very severe indicates that significant erosion is expected, loss of soil productivity and off-site damage are likely, and erosioncontrol measures are costly and generally impractical (NRCS 2015). The erosion potential for soils within the plan area is presented in Exhibit Subsidence Land subsidence is the gradual settling or sinking of an area with very little horizontal motion. It occurs because of changes taking place underground. Land surface subsidence can be induced by both natural and human phenomena. Natural phenomena include subsidence resulting from shifting of tectonic plates and dissolution of limestone resulting in sinkholes. Subsidence related to human activity includes pumping water, oil, or gas from underground reservoirs; collapse of underground mines; drainage of wetlands; and soil compaction. Subsidence can be problematic because it threatens the stability of roads, bridges, canals, and other infrastructure. Land subsidence in California is a problem that has been acknowledged and is tied to groundwater pumping. The state has exhibited escalating occurrence and severity of land subsidence since monitoring programs began in California decades ago (California Department of Water Resources 2017). Monitoring of subsidence in Yolo County has been occurring since 1999 on a regional level (Yolo County Flood Control and Water Conservation District 2006). Subsidence is not uniform throughout the plan area. Subsidence on campus has been linked to groundwater pumping and has occurred gradually over the years as water has been drawn from the shallow and intermediate aquifers for agricultural and utility uses (City of Davis 2001). A monitoring network has been established to document continuing subsidence and to manage groundwater pumping to avoid overdraft and subsidence Long Range Development Plan EIR

12 Geology, Soils, and Seismicity Exhibit 3.7-2: Linear Extensibility (Shrink-Swell Potential) of Soils in the Plan Area Long Range Development Plan EIR

13 Geology, Soils, and Seismicity Exhibit 3.7-3: Erosion Hazard of Soils in the Plan Area 2018 Long Range Development Plan EIR

14 Geology, Soils, and Mineral Resources Environmental Impacts and Mitigation Measures SIGNIFICANCE CRITERIA Based on Appendix G of the State CEQA Guidelines, the project would result in a potentially significant impact on geology, soils, and mineral resources if it would: expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: 1. rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault. Refer to Division of Mines and Geology Special Publication 42, 2. strong seismic ground shaking, 3. seismic--related ground failure, including liquefaction, or 4. landslides; result in substantial soil erosion or the loss of topsoil; be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landslides, lateral spreading, subsidence, liquefaction or collapse; be located on expansive soil, as defined in Table 18 1 B of the Uniform Building Code (1994), creating substantial risks to life or property; have soils incapable of adequately supporting the use of septic tanks or alternative wastewater disposal systems where sewers are not available for the purposes of the disposal of wastewater; directly or indirectly destroy a unique paleontological resource or site or unique geologic feature; result in the loss of availability of a known mineral resource that would be of value to the region and the residents of the state; or result in the loss of availability of a locally-important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan. ANALYSIS METHODOLOGY To evaluate project impacts, resource conditions that could pose a risk to the 2018 LRDP were identified through review of documents pertaining to these topics within the plan area. Sources consulted include USGS and CGS technical maps and guides; the NRCS Soil Survey (SSURGO 2017); previous environmental impact reports; background reports prepared for nearby plans and projects; and published geologic literature. The information obtained from these sources was reviewed and summarized to establish the existing conditions (described above) and identify potential environmental hazards. In determining level of significance, the analysis assumes that the project alternatives would comply with relevant laws, regulations, and guidelines. Potential effects associated with implementation of the 2018 LRDP are characterized as permanent. Temporary effects from construction of specific components of the 2018 LRDP would be evaluated on a project-level basis Long Range Development Plan EIR

15 Geology, Soils, and Mineral Resources ISSUES NOT EVALUATED FURTHER Surface Fault Rupture The Campus and surrounding area are not located within an Alquist-Priolo Earthquake Fault Zone. The nearest faults identified pursuant to the Alquist-Priolo Act are the Green Valley and Cordelia Faults, which are a part of the San Andreas Fault System, approximately 27 miles southwest of the plan area. Additionally, the nearest identified active fault zone is the Dunnigan Hills Fault zone located 16.5 miles north of the plan area. The campus would not be subject to surface fault rupture; and this issue is not evaluated further in this EIR. Landslides The potential for landslides within the plan area is low because of the lack of significant slopes and acting gravitational forces. The campus would not be subject to landslides; and this issue is not discussed further in this EIR. Paleontological Resources The entirety of the project site is underlain by quaternary alluvium from the Holocene period that is generally less than 10,000 years old. This alluvium consists of sand, silt, and gravel deposited in fan, valley fill, terrace, or basin environments. These alluvial deposits contain vertebrate and invertebrate remains of extant, modern taxa, which are generally not considered paleontologically significant. The plan area has been subject to significant recent and historical disturbance of the land, and therefore is unlikely to yield heretofore unknown or undiscovered paleontological resources during development under the 2018 LRDP. Moreover, the campus is situated within the Sacramento/Central Valley, which does not have any notable bedrock outcroppings. The soils of the area are deep, unconsolidated, alluvial units with a low likelihood of producing fossils. Therefore, no impacts related to paleontological resources would occur; and this topic is not further evaluated in this EIR. Mineral Resources Although in the past, small amounts of gold and silver were mined from Putah Creek, currently, the chief mineral resources mined in Yolo County are aggregate rock and natural gas (Yolo County 2009), and the primary mineral resource mined in Solano County is also aggregate rock (Solano County 2008). The plan area is located in MRZ-1, which is an area where there is sufficient information to determine that no significant mineral deposits (specifically aggregate rock) are present. Additionally, the site is not indicated as a locally important mineral resource site. As a result, impacts related to mineral resources would not occur, and this issue is not discussed further in this EIR. IMPACTS AND MITIGATION MEASURES Impact 3.7-1: Risk of exposure of people or buildings to seismic ground shaking. is within the vicinity of areas where large earthquakes may originate, but is not directly in an Alquist-Priolo Earthquake Fault Zone, or a Seismic Hazard Zone mapped pursuant to the Seismic Hazards Mapping Act. In the event of an earthquake strong enough to produce shaking on campus, project components could be subjected to ground shaking. Proposed project structures would be designed and constructed in accordance with the current seismic safety and structural design requirements set forth in the CBC. Therefore, there would be no substantial risk of loss, injury, death, or property damage from strong seismic shaking associated with new development under the 2018 LRDP. For these reasons, the 2018 LRDP would have a less-than-significant impact related to exposure of people or structures to seismic hazards Long Range Development Plan EIR

16 Geology, Soils, and Mineral Resources As noted above, the plan area is not located in a regulated Alquist-Priolo Earthquake Fault Zone or a Seismic Hazard Zone; however, there are tectonically active areas to the north and west of the project, including the Dunnigan Hills Fault, the Cordelia Fault Zone, and the Green Valley Fault (the latter two are components of the San Andreas Fault System). These fault zones are within a distance that could subject the plan area to a moderate level of seismic ground shaking, which could result in damage to structures and injury or death to people if they are within structures that fail. The peak ground acceleration (2 percent in 50 years) for the central, west, and south campus areas is estimated to be approximately g, and closer to 0.6g on the western portion of campus at Russell Ranch. This level of seismic activity has the potential to dislodge objects from shelves and to damage or destroy buildings and other structures. While development under the 2018 LRDP would not risk exacerbating seismic hazards on campus, it would expose more people to risks associated with damage from earthquakes. The campus minimizes these seismically-induced risks through several measures. Damage or destruction to buildings and other structures is minimized through review of draft building plans for compliance with the CBC, which, as noted above, includes specific structural seismic safety provisions. The campus also adheres to the University of California Seismic Safety Policy, which requires anchorage for seismic resistance of nonstructural building elements such as furnishings, fixtures, material storage facilities, and utilities that could create a hazard if dislodged during an earthquake. EHS provides guidance for preparing department-level Illness and Injury Prevention Plans that emphasize methods for minimizing seismic hazards in laboratories, for example, by properly securing chemical containers and gas cylinders. Each department has a Safety Coordinator who develops and maintains a departmental emergency response plan. The departmental emergency response plans must be submitted to the Emergency Preparedness Policy Group for annual review to assure consistency with the campus Emergency Operations Plan, which includes seismic safety and building evacuation procedures. The emergency procedures incorporated into the departmental emergency response plans further reduce the hazards from seismic shaking by preparing faculty, staff, and students for emergencies. Taken together, these procedures would ensure that hazards associated with seismic ground shaking would be less than significant. Mitigation Measures No mitigation measures are necessary. Impact 3.7-2: Potential for liquefaction caused by an earthquake. The campus is located in a seismically active area with soils that could be susceptible to liquefaction and structural settlement in the event of an earthquake. The campus eliminates these hazards through compliance with the CBC, which includes geotechnical investigations of sites prior to development; and implementation of structural design features to eliminate the risk of liquefaction. This results in a less-than-significant impact with respect to exposure. Liquefaction is a hazard associated with seismic activity, wherein seismic waves cause pressure in loose sand grains and cause sediments to behave like a liquid. It is not caused or exacerbated by the presence of development; however, development in areas susceptible to liquefaction can expose people to the risk of building settlement or structural failure. Soils on campus exhibit characteristics which could make them susceptible to liquefaction; however, depth to groundwater on campus is relatively deep (30 to 80 feet below ground surface), which provides a mitigating effect because most soils are not continuously saturated. Therefore, many campus soils that are characterized as susceptible in literature may be discovered to be not so during geotechnical investigations. Geotechnical investigations that address the potential for liquefaction, lateral spreading, and other types of ground failure are required for every development project on campus, in compliance with Long Range Development Plan EIR

17 Geology, Soils, and Mineral Resources the CBC. The geotechnical work informs the type of building foundations and pre-construction stabilization that is required for buildings. With continued implementation of this procedure and compliance with the CBC and the University of California Seismic Safety Policy, this impact would be less than significant. Mitigation Measures No mitigation measures are necessary. Impact 3.7-3: Potential for construction activities to disturb soils and result in erosion or loss of topsoil. Construction of individual projects would involve clearing and grading at projects sites and trenching in areas where utility infrastructure would be laid. Campus projects would have to comply with relevant National Pollutant Discharge Elimination System (NPDES) permits, including the General Permit for Storm Water Discharges Associated with Construction Activity (General Construction Permit) and the General Permit for Storm Water Discharges from Small Municipal Separate Storm Sewer Systems (Phase II Small MS4 Permit), which require soil erosion control measures. In addition, individual projects would be designed such that there would be minimal disturbance to existing vegetation, especially redevelopment projects where existing landscaping can be preserved or enhanced. The result would be a less-than-significant impact on soil erosion. Construction of individual projects implemented under the 2018 LRDP would involve clearing and grading in areas where new or replacement structures would be built and would involve trenching for placement of utility connections. Topsoil or vegetation would need to be cleared and would be temporarily stockpiled for reuse on sites or for landscaping and non-structural area cover. Most of the soil located within the campus boundary has low susceptibility to erosion (Exhibit 3.7-3) under steady state conditions. While these soils are in some cases easily detachable by rain and runoff, slope characteristics on campus do not create a high proclivity for soil erosion. However, soil disturbance changes this dynamic, increasing the rate at which soil is eroded, affecting soil productivity and/or stability. Consequently, activities associated with construction from the 2018 LRDP projects have the potential to exacerbate the erosive force of surface runoff. The elevated risk of erosion associated with construction activity has long been acknowledged by regulators. Consequently, there are robust programs aimed at mitigating these effects encoded in laws and regulations, at various levels of government. The two primary safeguarding regulations are the state CBC and federal NPDES program (for a detailed description of the NPDES program and requirements, including the provisions of these permits, see Section 3.10, Hydrology and Water Quality ). While the CBC is aimed chiefly at building standards, and the NPDES program at protecting receiving waters from pollution, these two programs are applicable to development under the 2018 LRDP, and together ensure strong protection against erosion, as described below. The CBC contains standards for soil compaction, sediment control during construction, and revegetation following construction, as well as other standards. would revegetate disturbed areas and would implement best management practices (BMPs) according to guidance in the California Stormwater Quality Association Stormwater Best Management Practice Handbooks for Construction. Individual projects would be implemented to minimize removal of trees, vegetation, or other cover which could otherwise contribute to increased rates of erosion. Alternatively, or in combination with preservation of existing vegetation, projects would be implemented with site design measures or low impact development design features, which in many cases involve revegetation to be specially designed to enhance runoff infiltration and prevent erosion. Site design measures and low 2018 Long Range Development Plan EIR