IV. Environmental Impact Analysis D. Geology 1. Introduction This section evaluates potential geologic hazards and soil conditions associated with the proposed project, including fault rupture, ground shaking, ground failure (i.e., liquefaction), expansive soils, sedimentation, and erosion. The analysis is largely based on information and findings contained in the Preliminary Geotechnical Engineering Investigation (Geotechnical Report) prepared by Geotechnologies, Inc. on June 10, 2008, and provided in Appendix E of this Draft EIR. 2. Environmental Setting a. Existing Conditions (1) Regional Geology The project site is located within the Los Angeles Basin of the Peninsular Ranges geomorphic province. The basin is bounded on the east and southeast by the Santa Ana Mountains and San Joaquin Hills, and to the northwest by the Santa Monica Mountains. The Peninsular Ranges are characterized by northwest-trending blocks of mountain ridges and sediment-floored valleys. The dominant geologic structural features are northwest trending fault zones that either die out to the northwest or terminate at east-trending reverse faults that form the southern margin of the Transverse Ranges. (2) Site Geology (a) Topography The gentle topography of the site presents a westward increase in elevation of approximately 65 feet over a distance of nearly 3,000 feet. The highest elevation of the site is at the northwest corner, with the lowest point at the northwest corner at the intersection of S. Grande Vista Avenue and Lydia Drive. From this point, an open and unlined flood control channel extends through the center of the site in a general westerly direction. Page IV.D-1
(b) Subsurface Soils The project site is underlain by fill soils to a maximum depth of 18 feet. The fill soils consist primarily of moist, stiff to medium density, fine-grained silty to sandy clays and clayey to silty sands which are yellowish brown to brownish grey, mixed with some gravel. The native soils underlying the fill on-site consist predominantly of sands, silty sands, clayey sands, and sandy silts. The native soils are generally fine-grained with some gravel and cobbles, range from orange brown to yellowish brown to brownish grey in color, and are dense to very dense and hard. The geologic materials consist predominantly of alluvial sediments deposited by rivers and streams, typical of the Los Angeles County area. Soil borings performed on-site to a depth of 100 feet did not encounter groundwater. Groundwater is assumed to occur at 150 feet or more below ground surface (bgs), based on the historical high groundwater level documented by the California Division of Mines and Geology (CDMG). 1 However, this estimate may vary throughout the project area based on fluctuations in rainfall, temperature, and other localized factors. (3) Geologic Hazards (a) Fault Rupture Fault rupture is defined as the displacement that occurs along the surface of a fault during an earthquake. Based on criteria established by the California Geological Survey (CGS), faults can be classified as active, potentially active, or inactive. Active faults are those that have shown evidence of movement within the past 11,000 years (i.e., Holocene era). Potentially active faults are those that have shown evidence of movement between 11,000 and 1.6 million years ago (i.e., Pleistocene era). Inactive faults are those that have not exhibited displacement more recently than 1.6 million years before the present. Additionally, there are blind thrust faults, which are low angle reverse faults with no surface exposure. Due to their buried nature, the existence of blind thrust faults is usually not known until they produce an earthquake. The seismically active region of Southern California is crossed by numerous active and potentially active faults and is underlain by several blind thrust faults. As discussed further below, the Alquist-Priolo Earthquake Fault Zoning Act requires the State Geologist to establish earthquake fault zones around the surface traces of active faults and to issue appropriate maps to assist cities and counties in planning, zoning, and building regulation functions. These zones, which generally extend from 200 to 500 feet on each side of a 1 The California Division of Mines and Geology is now called the California Geological Survey. Page IV.D-2
known active fault, identify areas where potential surface rupture could prove hazardous and where special studies are required to characterize hazards to habitable structures. Based on the Geotechnical Report, no known active or potentially active faults underlie the project site. As such, the potential for surface ground rupture at the site is considered low. 2 Accordingly, the project site is not located within an Alquist-Priolo Fault Study Zone or within a Fault Rupture Study Area. 3 The closest faults identified near the project site include the Puente Hills Blind Thrust Fault, a thrust system made up of the Los Angeles, Santa Fe Springs, and Coyote Hills segments, which passes below the project vicinity but does not reach the ground surface, and the Upper Elysian Park Blind Thrust Fault, located approximately 2.7 miles from the site. 4 Buried or blind thrust faults are faults without a surface expression but are a significant source of seismic activity. They are typically broadly defined, based on the analysis of seismic wave recordings of hundreds of small and large earthquakes in the Southern California area. Due to the buried nature of these thrust faults, their existence is usually not known until they produce an earthquake. These blind thrusts are characterized by propagation folding manifested at the earth s surface by anticlinal fold belts with topographic relief, such as the Elysian Park, Repetto, and Puente Hills blind thrusts. The Puente Hills Blind Thrust is located just east of downtown Los Angeles. It has been postulated that this feature has caused at least four large earthquakes in the last 11,000 years. Just north of downtown Los Angeles, the Elysian Park anticline underlies Elysian Park and the Repetto Hills. The Elysian Park Blind Thrust has been postulated to produce a large earthquake every 500 to 1,300 years. The closest active fault identified for the project site is the Hollywood-Raymond Fault located approximately 6 miles north of the project site. 5 The Raymond Fault is the eastern segment of the Malibu Santa Monica Hollywood Fault. Other active faults in the vicinity include the Newport-Inglewood Fault located approximately 8 miles to the southwest of the project site and the Verdugo Eagle Rock Fault located approximately 8 miles north of the project site. 6 2 3 4 5 6 Geotechnologies, Inc., Primary Geotechnical Engineering Investigation, File No. 19101, June 2008. General Plan Safety Element, Exhibit A, adopted by the City Council, November 13, 1996. Geotechnologies, Inc., Primary Geotechnical Engineering Investigation, File No. 19101, June 2008; and Journal of Structural Geology, Application of three fault growth criteria to the Puente Hills thrust system, Los Angeles, CA, USA, 2005, www.geo.umass.edu/faculty/cooke/la/olson&cooke.pdf. California Geological Survey, Department of Conservation, Division of Mines and Geology Special Publication 42, Seismic Hazards Zone Map Los Angeles Quadrangle, released March 25, 1999. California Geological Survey, 2002 California Fault Parameters Transverse Ranges and Los Angeles Basin, www.conservation.ca.gov/cgs/rghm/psha/fault_parameters/htm/pages/ca_flt_parameters_tr_la1.aspx, site accessed November 13, 2008. Page IV.D-3
Additionally, the General Plan Safety Element designates fault rupture study areas extending along each side of active and potentially active faults to establish areas of hazard potential due to fault rupture. The project site is not located within a City-designated fault rupture study area. 7 (b) Ground Shaking As stated above, the project site is not located within a State-designated Alquist- Priolo earthquake fault zone or a City-designated fault rupture study area. However, it is located in the seismically active region of Southern California. Therefore, the project site may be subject to strong seismic ground shaking, either as a result of seismic events along the aforementioned faults in the area or more distant faults in the region. (c) Dynamic Dry Settlement Ground motion can create dynamic dry settlement, which is the seismically induced settlement or compaction of dry or moist, cohesionless soils. This type of settlement has the potential to cause the most damage when the settlement rates differ from one end of a structure to the other. Given that the underlying soils on the project site are generally uniform, excessive differential settlements are not anticipated. (d) Seiches and Flooding Seiches are oscillations of enclosed bodies of water caused by earthquake-induced ground shaking. Per the County of Los Angeles Flood and Inundation Map, the project site is not located within an area susceptible to flooding due to a seiche or breached reservoir. (e) Liquefaction Liquefaction is a form of earthquake-induced ground failure that occurs primarily in relatively shallow, loose, granular, water-saturated soils. Liquefaction can occur when these types of soils lose their inherent shear strength due to excess water pressure that builds up during repeated movement from seismic activity. A shallow groundwater table, the presence of loose to medium dense sand and silty sand, and a long duration and high acceleration of seismic shaking are factors that contribute to the potential for liquefaction. Liquefaction usually results in horizontal and vertical movements from lateral spreading of liquefied materials and post-earthquake settlement of liquefied materials. 7 General Plan Safety Element, Exhibit A, adopted by the City Council, November 26, 1996. Page IV.D-4
As discussed further below, the Seismic Hazards Mapping Act requires the State Geologist to delineate seismic hazard zones in areas where the potential for strong ground shaking, liquefaction, landslides, and other ground failures due to seismic events are likely to occur. Cities and counties must regulate certain development projects within these zones until the geologic and soil conditions of the associated project site are investigated and appropriate mitigation measures, if any, are incorporated into development plans. Based on the seismic hazard zone map for the Los Angeles Quadrangle, the project site is not located within a State-designated liquefaction zone of required investigation. 8 The General Plan Safety Element also designates areas susceptible to liquefaction. The project site is not located within an area designated by the California Geological Survey or by the for potential liquefaction. 9,10 (f) Landsliding Seismic activity can also create the potential for landslides. However, the probability of seismically induced landslides on the site is low due to the gentle sloping nature of the site. (g) Expansive Soils Expansive soils are typically associated with fine-grained clayey soils that have the potential to shrink and swell with repeated cycles of wetting and drying. Changes in soil moisture content can result from rainfall, landscape irrigation, utility leakage, roof drainage, perched groundwater, drought, or other factors and may cause unacceptable settlement or heave of structures, concrete slabs on grade, or pavements supported over these materials. Depending on the extent and location below finished subgrade, expansive soils could have a detrimental effect on proposed construction. Based on the Geotechnical Report conducted for the project site, the earth materials identified on-site are in the very low to moderate expansion range. As also indicated in the Geotechnical Report, such soils do not necessitate development considerations beyond the City s relevant building and seismic standards. 8 9 Edward F. Hill, Preliminary Geotechnical Engineering Investigation for Proposed Residential Development Southeast Corner 8th Street and Soto Street, Los Angeles, CA ; Geotechnologies, Inc., June 10, 2008. California Geological Survey, Department of Conservation, Division of Mines and Geology Special Publication 42, Seismic Hazards Zone Map Los Angeles Quadrangle, released March 25, 1999. 10 Planning Department, Safety Element of the General Plan, Exhibit B, Areas Susceptible to Liquefaction, October 1993. Page IV.D-5
(h) Sedimentation and Erosion As defined by Los Angeles Municipal Code (LAMC) Section 91.7003, erosion is the wearing away of the ground surface as a result of the movement of wind, water or ice. Sedimentation occurs when solid materials, such as dust and dirt, are deposited after being in a state of suspension in air or water. Sedimentation and erosion are factors which contribute to soil instability and subsequent geologic hazards on-site as well as to neighboring properties. Both can occur as result of grading and excavation activities, soil stockpiling, and surface water flows and drainage, both during construction and operation of a project. Please refer to Section IV.F, Hydrology and Water Quality, of this Draft EIR for additional discussion regarding erosion and sedimentation. b. Regulatory Framework (1) State of California (a) Alquist-Priolo Earthquake Fault Zoning Act The Alquist-Priolo Earthquake Fault Zoning Act (Public Resources Code [PRC] Section 2621) was enacted by the State of California in 1972 to address the hazard of surface faulting to structures for human occupancy. 11 The Alquist-Priolo Earthquake Fault Zoning Act was a direct result of the 1971 San Fernando Earthquake, which was associated with extensive surface fault ruptures that damaged homes, commercial buildings, and other structures. The primary purpose of the Alquist-Priolo Earthquake Fault Zoning Act is to prevent the construction of buildings intended for human occupancy on the surface traces of active faults. It is also intended to provide citizens with increased safety and to minimize the loss of life during and immediately following earthquakes by facilitating seismic retrofitting to strengthen buildings against ground shaking. The Alquist-Priolo Earthquake Fault Zoning Act requires the State Geologist to establish regulatory zones, known as earthquake fault zones, around the surface traces of active faults and to issue appropriate maps to assist cities and counties in planning, zoning, and building regulation functions. Maps are distributed to all affected cities and counties for the controlling of new or renewed construction and are required to sufficiently define potential surface rupture or fault creep. The State Geologist is charged with continually reviewing new geologic and seismic data, revising existing zones, and delineating additional earthquake fault zones when warranted by new information. Local agencies must enforce the Alquist-Priolo Earthquake Fault Zoning Act in the development permit process, where applicable, and 11 The Act was originally entitled the Alquist-Priolo Geologic Hazards Zone Act. Page IV.D-6
may be more restrictive than State law requires. According to the Alquist-Priolo Earthquake Fault Zoning Act, before a project can be permitted, cities and counties shall require a geologic investigation prepared by a licensed geologist to demonstrate that buildings will not be constructed across active faults. If an active fault is found, a structure for human occupancy cannot be placed over the trace of the fault and must be set back. Although setback distances may vary, a minimum 50-foot setback is required. The Alquist- Priolo Earthquake Fault Zoning Act and its regulations are presented in California Department of Conservation, California Geological Survey, Special Publications (SP) 42, entitled Fault-Rupture Hazard Zones in California. (b) Seismic Hazards Mapping Act In order to address the effects of strong ground shaking, liquefaction, landslides, and other ground failures due to seismic events, the State of California passed the Seismic Hazards Mapping Act of 1990 (PRC Section 2690-2699). Under the Seismic Hazards Mapping Act, the State Geologist is required to delineate seismic hazard zones. Cities and counties must regulate certain development projects within these zones until the geologic and soil conditions of the associated project site are investigated and appropriate mitigation measures, if any, are incorporated into development plans. The State Mining and Geology Board provides additional regulations and policies to assist municipalities in preparing the Safety Element of their General Plan and encourage land use management policies and regulations to reduce and mitigate those hazards to protect public health and safety. Under PRC Section 2697, cities and counties shall require, prior to the approval of a project located in a seismic hazard zone, a geotechnical report defining and delineating any seismic hazard. Each city or county shall submit one copy of each geotechnical report, including mitigation measures, to the State Geologist within 30 days of its approval. State publications supporting the requirements of the Seismic Hazards Mapping Act include the CGS SP 117, Guidelines for Evaluating and Mitigating Seismic Hazards in California, and CGS SP 118, Recommended Criteria for Delineating Seismic Hazard Zones in California. The objectives of SP 117 are to assist in the evaluation and mitigation of earthquake-related hazards for projects within designated zones of required investigations and to promote uniform and effective Statewide implementation of the evaluation and mitigation elements of the Seismic Hazards Mapping Act. SP 118 implements the requirements of the Seismic Hazards Mapping Act in the production of Probabilistic Seismic Hazard Maps for the State. (c) California Building Code The California Building Code (CBC), found in Title 24 of the California Code of Regulations (CCR), is a compilation of building standards, including seismic safety Page IV.D-7
standards for new buildings. CBC standards are based on building standards that have been adopted by state agencies without change from a national model code; building standards based on a national model code that have been changed to address particular California conditions; and building standards authorized by the California legislature but not covered by the national model code. Given the State s susceptibility to seismic events, the seismic standards within the CBC are among the strictest in the world. The CBC applies to all occupancies in California, except where stricter standards have been adopted by local agencies. The State recently adopted the 2010 CBC, which became effective on January 1, 2011. Specific CBC building and seismic safety regulations have been incorporated by reference in the Los Angeles Municipal Code with local amendments. (2) (a) Los Angeles General Plan Safety Element The City s General Plan Safety Element, adopted in 1996, addresses public safety risks due to natural disasters including seismic events and geologic conditions, and sets forth guidance for emergency response during such disasters. The objective of the Safety Element is to better protect occupants and equipment during various types and degrees of seismic events. The Safety Element also provides maps of designated areas within the City that are considered susceptible to earthquake-induced hazards such as fault rupture and liquefaction. In addition, specific guidelines are included for the evaluation of liquefaction, tsunamis, seiches, non-structural elements, fault rupture zones, and engineering investigation reports. As discussed above, the project site is not located within a fault rupture study area or an area of potential liquefaction, as designated in the Safety Element. (b) Los Angeles Emergency Operations Organization The City s Emergency Operations Organization (EOO) helps to administer certain policies and provisions of the Safety Element. The EOO is a City department comprised of all City agencies. The Administrative Code, EOO Master Plan and associated EOO plans establish the chain of command, protocols and programs for integrating all of the City s emergency operations into one unified operation. Each City agency in turn has operational protocols, as well as plans and programs, to implement EOO protocols and programs. A particular emergency or mitigation triggers a particular set of protocols that are addressed by implementing plans and programs. The City s emergency operations program encompasses all of these protocols, plans and programs. Page IV.D-8
(c) Los Angeles Municipal Code Earthwork activities, including grading, are governed by the Los Angeles Building Code, which is contained in LAMC Chapter IX, Article 1. Specifically, Section 91.7006.7 contains requirements regarding the import and export of soil materials; Section 91.7010 includes regulations pertaining to excavations; Section 91.7011 includes requirements for fill materials; Section 91.7013 addresses erosion control and drainage devices; Section 91.7014 includes general construction requirements as well as requirements regarding flood and mudflow protection; and Section 91.7016 contains regulations for areas that are subject to slides and unstable soils. Additionally, the Los Angeles Building Code includes specific requirements addressing seismic design, grading, foundation design, cut and fill slope design, soil expansion, geologic investigations and reports before and during construction, retaining walls, soil and rock testing, shoring of adjacent properties, potential primary and secondary seismic effects, and groundwater. The Los Angeles Building Code incorporates by reference the 2010 CBC, with City amendments for additional requirements. The City Department of Building and Safety is responsible for implementing the provisions of the Los Angeles Building Code. 3. Environmental Impacts a. Methodology This analysis of impacts associated with geology and soils is based primarily on the Geotechnical Report prepared by Geotechnologies, Inc. in June 2008. The Geotechnical Report included field exploration (i.e., exploratory soil borings) and laboratory testing to determine the characteristics of the subsurface conditions at the project site. These subsurface conditions were then analyzed to evaluate the potential for construction and operation of the proposed project to result in significant impacts relative to geology and soils. Recommendations regarding the design and construction of the proposed project are based on these results. b. Thresholds of Significance (1) Geologic Hazards According to the CEQA Thresholds Guide (2006), a project would normally have a significant geologic hazard impact if it would: Cause or accelerate geologic hazards, which would result in substantial damage to structures or infrastructure, or expose people to substantial risk of injury. Page IV.D-9
(2) Sedimentation and Erosion According to the CEQA Thresholds Guide (2006), a project would normally have significant sedimentation or erosion impacts if it would: Constitute a geologic hazard to other properties by causing or accelerating instability from erosion; or Accelerate natural processes of wind and water erosion and sedimentation, resulting in sediment runoff or deposition which would not be contained or controlled on-site. (3) Landform Alteration According to the CEQA Thresholds Guide (2006), a project would normally have a significant impact on landform alteration if: One or more distinct and prominent geologic or topographic features would be destroyed, permanently covered, or materially and adversely modified as a result of the project. Such features may include, but are not limited to, hilltops, ridges, hillslopes, canyons, ravines, rock outcrops, water bodies, streambeds, and wetlands. c. Project Design Features Construction of the project would be implemented in accordance with all State and City regulations addressing geologic hazards and the protection of public safety. These regulations identify appropriate design standards and construction methodologies to protect the public. In particular, activities associated with the grading and export of soil would occur in accordance with City requirements, as specified in the LAMC and through the grading plan review and approval process. d. Analysis of Project Impacts (1) Geologic Hazards (a) Fault Rupture As discussed above, based on research of available literature and the results of site reconnaissance, no known active or potentially active faults underlie the project site. The closest faults identified near the project site include the Puente Hills Blind Thrust Fault, Page IV.D-10
which passes below the project vicinity but does not reach the ground surface, and the Upper Elysian Park Blind Thrust Fault, located approximately 2.7 miles from the site. However, the seismic risk of these buried structures in terms of recurrence and maximum potential magnitude is not well established. While the potential for surface rupture on these surface-verging splays at magnitudes higher than 6.0 cannot be precluded, the risk for surface rupture potential of these buried thrust faults is inferred to be low. 12 In addition, the project site is not located within a State-designated earthquake fault zone or City-designated fault rupture study area. Thus, the potential for surface ground rupture at the project site is considered low. Development of the proposed project would not result in substantial damage to structures or infrastructure, or expose people to substantial risk of injury involving rupture of a known earthquake fault. Impacts regarding fault rupture would therefore be less than significant. (b) Ground Shaking The project site is located within the seismically active region of Southern California. The level of ground shaking that would be experienced at the project site from active, potentially active faults or blind thrust faults in the region would be a function of several factors including earthquake magnitude, type of faulting, rupture propagation path, distance from the epicenter, earthquake depth, duration of shaking, site topography, and site geology. According to the Geotechnical Report, moderate to strong ground motion (acceleration) could be caused by an earthquake on any of the local or regional faults. Exposure of the site to seismic events was analyzed using: (1) the deterministic method; and (2) the probabilistic method. The deterministic method calculates the estimated maximum earthquake magnitude for a fault based on formulas which correlate the fault trace to the theoretical maximum magnitude earthquake. Using the deterministic methodology, the largest maximum magnitude event to impact the project site may be a 7.1 magnitude earthquake as a result of the Puente Hills Blind Thrust Fault, which would be expected to cause ground shaking motion on-site with a maximum acceleration of 1.0131 g (i.e., 1.0131 times the acceleration of gravity). As detailed in the Geotechnical Report, numerous faults in the region are capable of earthquakes with a maximum magnitude of 6.4 and higher. The probabilistic method considers the probability of exceedance of various levels of ground motion (acceleration) and is calculated by consideration of risk contributions from all possible earthquake scenarios on all faults within a prescribed search radius. Structural designs typically take into account earthquakes with a 10 percent and 50 12 Leighton, 1990. Page IV.D-11
percent probability of exceedance, which were calculated to generate mean accelerations of motion of 0.43 g and 0.23 g, respectively, at the project site. According to the Geotechnical Report, the project site is identified as Site Classification D, which corresponds to a Stiff Soil Profile for seismic design in accordance with the 2010 CBC. As such, as with any new project development in the State of California, building design and construction would conform to the current seismic design provisions of the CBC. The 2010 CBC incorporates the latest seismic design standards for structural loads and materials, as well as provisions from the National Earthquake Hazards Reduction Program (NEHRP) to mitigate losses from an earthquake and provide for the latest in earthquake safety. Additionally, construction of the proposed project would be required to adhere to the seismic safety requirements contained in the LAMC. Based on the results of the Geotechnical Report, development of the proposed project is considered feasible from a geotechnical perspective provided that the applicable regulations and recommendations provided are implemented. Preliminary design recommendations are set forth in the Geotechnical Report with regard to seismic design and other geotechnical issues. Compliance with the CBC, LAMC, and Mitigation Measure D-1 below would ensure that adequate structural protection would be provided in the event of an earthquake, thus reducing impacts from strong seismic ground shaking to a less than significant level. (c) Liquefaction The project site is not classified by the CGS as a liquefaction area, nor is it designated by the for potential liquefaction. This determination was based on groundwater depth records, soil type, and distance to a fault capable of producing a substantial earthquake. As indicated in the Geotechnical Report, the vast majority of liquefaction hazards are associated with sandy soils and silty soils of low plasticity. An analysis of the density of the site soils and the depth of the groundwater indicate that the liquefaction potential of the site is remote. As such, impacts regarding liquefaction on-site would be less than significant. (d) Other Geologic Hazards The project site and surrounding area are relatively flat with no pronounced highs or lows. Furthermore, the project site has previously been graded and developed and is located in an urbanized area. No distinct or prominent geologic or topographic features are located on the project site such as hilltops, ridges, slopes, canyons, ravines, rock outcrops, water bodies, streambeds, or wetlands. Therefore, no impact from landslides or other forms of natural slope instability or landform alteration would occur on the project site. Page IV.D-12
According to the Safety Element of the General Plan, the project area is not mapped as a potential inundation area. As such, no potential hazards regarding inundation are expected and no impacts would occur. (2) Subsurface Soils (a) Expansive Soils Based on the Geotechnical Report, expansion tests performed in accordance with the Expansion Index testing procedures indicate the on-site earth materials are in the low to moderate expansion range. Per the Geotechnical Report, due to this low to moderate potential for expansion, no design recommendations regarding expansive soils beyond the minimum required by the City s Department of Building and Safety are necessary. With adherence to the City s minimum standards, potential impacts regarding expansive soils would be less than significant. (b) Sedimentation and Erosion During project construction, approximately 1,084,400 cubic yards would be excavated for project development. Of this, approximately 123,200 cubic yards would be used for fill on-site, and approximately 961,300 cubic yards would be exported off-site. Erosion and sedimentation from exposed soils could potentially occur during construction. However, project construction activities would comply with erosion control requirements, including grading and dust control measures imposed by the City pursuant to grading permit regulations. Specifically, project construction would comply with LAMC Chapter IX, which requires necessary permits, plans, plan checks, and inspections to reduce the effects of sedimentation and erosion. In addition, the project would be required to have an erosion control plan approved by the Department of Building and Safety, as well as a Storm Water Pollution Prevention Plan (SWPPP) pursuant to the National Pollutant Discharge Elimination System (NPDES) permit requirements. As part of the SWPPP, Best Management Practices (BMPs) would be implemented during construction to reduce soil erosion and pollutant levels to the maximum extent possible. Therefore, construction-related impacts associated with erosion and sedimentation would be less than significant. After construction, the proposed project may result in a limited degree of soil erosion effects from vegetated areas. However, in accordance with NPDES requirements, the project would be required to have a Standard Urban Stormwater Mitigation Plan (SUSMP) in place during the operational life of the project, which would include BMPs designed to reduce on-site erosion from landscaped areas on the project site. As such, operational impacts associated with erosion and sedimentation would be less than significant. Page IV.D-13
Please refer to Section IV.F, Hydrology and Water Quality, of this Draft EIR, for additional analysis regarding potential erosion and sedimentation effects during project construction and operation, as well as further details regarding the project s SWPPP and SUSMP. (3) Consistency with Applicable Regulations (a) Alquist-Priolo Earthquake Fault Zoning Act As previously discussed, the project site is not located within a State-designated Alquist-Priolo earthquake fault zone. Therefore, the proposed project would not be subject to special design requirements (i.e., setbacks) or additional studies as required by the Alquist-Priolo Earthquake Fault Zoning Act. (b) Seismic Hazards Mapping Act In accordance with the Seismic Hazards Mapping Act, the liquefaction potential of the project site was investigated through the preparation of a Geotechnical Report. As indicated therein, the potential for liquefaction on-site is remote. Additionally, the project would comply with the safety guidelines set forth in CGS SP 117, as well as State and local building and safety codes, and preliminary design recommendations set forth in the Geotechnical Report, thus reducing seismic hazards to a less than significant level. Therefore, the project would be in compliance with the Seismic Hazards Mapping Act. (c) Los Angeles General Plan Safety Element The project site is not located within a City-designated liquefiable area. Nonetheless, the project would comply with the safety guidelines set forth in CGS SP 117, as well as State and local building and safety codes, and preliminary design recommendations set forth in the Geotechnical Report. As such, the project would be in compliance with the Los Angeles General Plan Safety Element. (d) Los Angeles Municipal Code and California Building Code The proposed project would be designed and constructed in accordance with all applicable LAMC requirements, which incorporate applicable provisions of the California Building Code, including those set forth regarding building safety and seismic risks. As such, the project would be in compliance with LAMC requirements as well as the CBC. Page IV.D-14
4. Cumulative Impacts Impacts associated with geologic and soil issues are typically confined to a project site or a very localized area and do not affect off-site areas. While growth is expected in the project area, none of the related projects identified in Section III, Environmental Setting, is located adjacent to or sufficiently close to the project site so as to present a potential for overlapping geologic effects with the proposed project. Cumulative development associated with the related projects and other ambient growth in the greater area would, however, increase the overall potential for exposure to geologic hazards by potentially increasing the number of people exposed to seismic events, or due to potentially hazardous geologic conditions that may exist at related project sites. Nevertheless, all future development, including the related projects, would be subject to established guidelines and regulations pertaining to geologic hazards. As such, adherence to applicable building regulations and standard engineering practices would ensure that cumulative impacts would be less than significant. 5. Project Design Features and Mitigation Measures a. Project Design Features Project Design Feature D-1: Construction of the project shall be implemented in accordance with all State and City regulations addressing geologic hazards and the protection of public safety. These regulations identify appropriate design standards and construction methodologies to protect the public. In particular, activities associated with the grading and export of soil shall occur in accordance with City requirements, as specified in the LAMC and through the grading plan review and approval process. b. Mitigation Measures Mitigation Measure D-1: Prior to issuance of a grading permit, a qualified geotechnical engineer shall be retained by the Applicant. The geotechnical engineer shall be present on the project site during excavation, grading, and general site preparation activities in order to monitor implementation of the recommendations specified in the Primary Geotechnical Investigation dated June 2008 prepared by Geotechnologies, Inc., as well as applicable regulations and other recommendations which may be made in subsequent geotechnical investigations prepared for the project. When appropriate, the Page IV.D-15
geotechnical engineer shall provide structure-specific geologic and geotechnical recommendations which shall be documented in a report to be appended to the project s geotechnical report(s). 6. Level of Significance After Mitigation With implementation of the project design features and Mitigation Measure D-1 above, potential impacts of the project associated with geology and soils would be reduced to less than significant levels. Page IV.D-16