5. Environmental Analysis

Transcription

1 5.4 This section of the DEIR evaluates the potential for implementation of the Puente Hills Intermodal Facility (PHIMF) project to impact geology and soils resources in the City of Industry and unincorporated County of Los Angeles. The analysis in this section is based in part on the following technical report: Limited Geotechnical Investigation Feasibility-Level Report, LACSD Intermodal Facility Project, KFM GeoScience, July 18, A complete copy of this study is included in Appendix E in Volume IIA of this DEIR. The analysis below is based on construction of the Preferred Access Option, which is referenced in the Limited Geotechnical Investigation as Alternative D Environmental Setting Regional Geologic Setting The proposed project is located within the San Gabriel River Basin, adjacent to the western flank of the Puente Hills. California is divided into geomorphic provinces, which are distinctive natural regions in which the geologic record, types of landforms, pattern of landscape features, and climate in all parts are similar. The project site is located within the Peninsular Ranges province. Regional faults within the Peninsular Ranges province are oriented in a southeast to northwest direction, including the Whittier fault, located approximately two miles southwest of the site. Uplift of the Puente Hills has exposed a thick sequence of tertiary marine sedimentary rocks, including the Pico Member of the Fernando Formation exposed in the lower western cut slope east of the project site. The predominately siltstone bedrock has been deformed by folding and faulting as the Puente Hills were uplifted. Alluvium deposited by the San Gabriel River and San Jose Creek overlies the bedrock beneath the majority of the PHIMF site. Geologic materials found within the existing Puente Hills Materials Recovery Facility (PHMRF) and proposed PHIMF project site include: Fill (af). Man-made fill was placed across much of the PHMRF site and beneath Workman Mill Road during construction of the storm drain within the San Jose Creek drainage. The fill encountered in an exploratory boring at the PHMRF consists of silty sand, clayey sand, sandy and gravelly silt, sandy and gravely clay, silt, and clay. The fill was also found to contain some scattered amount of rock fragments, concrete, asphaltic pavement, brick, plastic, and wood. In another soil boring, fill was found to consist of clay containing siltstone fragments and silty sand. Based on the available data, the fill thickness ranges up to 25 feet deep. Based on the limited geotechnical investigation, only limited, thin pockets of fill are anticipated to occur at the PHIMF site. Alluvium (Qal). Alluvium deposited by the San Gabriel River and San Jose Creek underlies the majority of the PHIMF site and railroad corridor alignment. The alluvium consists of loose to dense silty sand and sand, and medium stiff to stiff silt and clay. On the northwest side of Workman Mill Road, soil borings encountered 28 feet of alluvium consisting of silty sand, silt, and clay overlying siltstone bedrock. At the PHIMF site, soil borings encountered alluvium to the maximum explored depth of 60 feet below ground surface (bgs). The alluvium consists of approximately 25 to 30 feet of interlayered silty sand and sand overlying 5 to 15 feet of silt and clay, which is lying over 5 to 12 feet of silty sand. Puente Hills Intermodal Facility Draft EIR City of Industry Page 5.4-1

2 Landslide Debris (Qls). Based on previous investigations conducted for the PHMRF site, and the as-built mapping of the lower western cut slope, a portion of the PHMRF is underlain by landslide debris. The landslide debris has been described as blocky intact and disturbed weathered Pico Member bedrock that is closely to moderately fractured with widely variable bedding. The base of the landslide mass is characterized by a disturbed breccia zone 1 and thin, highly sheared clay seams. The landfill debris would impact only the construction of an approximately 250-foot section of a retaining wall proposed at the base of the lower western cut, where the existing internal access road at the PHMRF would be modified. Pico Member, Fernando Formation Bedrock (Tfp). Pico Member bedrock was encountered in the bottom of the investigation borings at the existing PHMRF site and near Workman Mill Road. The Pico Member bedrock was observed to consist primarily of massive siltstone and clayey siltstone that was typically gray to olive gray. The Pico Member contains infrequent lenses and thin beds of fine-grained sandstone, thin-sheared clay seams, and locally cemented layers. Bedding planes in the Pico Member generally dip 20 to 55 degrees toward the north, producing potentially adverse bedding conditions when the beds dip more shallowly than the adjacent descending slope. The presence of adverse bedding was most likely a controlling factor in the formation of the landslide described above. The Zee Medical Facility (Parcel A) is underlain by 15 to 20 feet of silty sand, which overlies about 15 feet of silt and silty sand. Groundwater is interpreted to be about 25 feet deep under the southeast end of the Zee Medical Facility and about 36 feet deep under the northwest end of the building that occupies this property. Based on review of the Quaternary Geologic Map of the El Monte Quadrangle contained in the California Geologic Survey (CGS) Seismic Hazard Evaluation of this quadrangle (CGS 1999), most of the rail corridor south of State Route 60 (SR-60) is underlain by younger alluvial basin deposits composed of sand, silt, and clay similar to the stratigraphy encountered at the PHIMF and PHMRF. Locally, an abandoned active stream wash 2 may be present where the rail corridor crosses Peck Road, resulting in the potential to uncover locally unconsolidated and looser/softer deposits. North of SR-60, the rail corridor may be underlain by older alluvial basin sediments that are expected to be dense to very dense. Geologic Hazards Slope Failure (Landslides) Landslides are movements of relatively large landmasses, either as nearly intact bedrock blocks, or as jumbled mixes of bedrock blocks, fragments, debris, and soils. Landslide materials are commonly porous and very weathered in the upper portions and along the margins of the slide. They may also have open fractures and joints. Slope failures can occur during or after periods of intense rainfall or in response to strong seismic shaking. Areas of high topographic relief, such as steep canyon walls, are most likely to be impacted by rockfalls, rockslides, and soil slips, and to a lesser degree, landslides. As shown in the Seismic Hazard Zones, El Monte Quadrangle map the project site is not located within an area with earthquakeinduced landslides (CGS 1999). 1 Breccia, or castic rock, is a sedimentary rock comprised of angular fragments from a previous rock structure, cemented in a matrix that may be of similar or different material 2 An abandoned active stream wash relates to streams that have not been abandoned in geologic time by directional changes of the flow, but rather abandoned due to recent development. Page The Planning Center December 2007

3 Compressible Soils Compressible soils are typically geologically young (Holocene age) unconsolidated sediments of low density that may compress under the weight of proposed fill embankments and structures. Geologic units that are generally susceptible to this hazard include young alluvium, the upper weathered part of older alluvium, colluvium/slope wash that collects near the base of natural slopes, slope failure debris and, in some cases, very weathered bedrock. The settlement potential and the rate of settlement in these sediments can vary greatly, depending on the soil characteristics (texture and grain size), natural moisture, density, and thickness of the compressible layer(s), the weight of the proposed load, the rate at which the load is applied, and drainage. Typically, overexcavation is required when grading sites with compressible soils. Overall, the on-site soils pose a moderate settlement potential and are not expected to impact construction options. Settlement at the administration and maintenance buildings at the PHIMF is expected to be less than 1 inch and less than 1.5 inches for the rubber-tired cranes foundation. The railroad bridges will be placed on piles and experience minimal settlement. Expansive Soils Fine-grained soils, such as silts and clays, may contain variable amounts of expansive clay minerals. These minerals can undergo significant volumetric changes as a result of changes in moisture content. The upward pressures induced by the swelling of expansive soils can have significant harmful effects upon structures and other surface improvements. Erosion Erosion, runoff, and sedimentation are influenced by several factors, including climate, topography, soil and rock types, and vegetation. Natural erosion processes are often accelerated through human activities. The project site is not located in an area with substantial variation in topography. Currently the majority of the site and surrounding areas have been developed and covered with impervious surfaces. Consequently, erosion is not a potential geologic hazard for the project site during post-construction conditions. Grading increases the potential for erosion and sedimentation by removing protective vegetation, altering natural drainage patterns, compacting the soil, and constructing cut-and-fill slopes that may be more susceptible to erosion than the natural condition. Developments also reduce the surface area available for infiltration, leading to increased flooding and sedimentation downstream of the project. Construction sites greater than one acre are required to prepare and implement a Storm Water Pollution Prevention Plan (SWPPP) to control for, among other pollutants, erosion and sedimentation generated during construction activities (see Section 5.6, Hydrology and Water Quality). Seismic Hazards The southern California region is known to be seismically active. The project site is located within Seismic Zone 4. Earthquakes occurring within approximately 60 kilometers of the site are generally capable of generating ground shaking of engineering significance to the proposed construction, as evidenced by the 1987 Whittier and 1994 Northridge earthquakes. Surface (Fault) Rupture Primary fault rupture refers to fissuring and offset of the ground surface along a rupturing fault during an earthquake. Primary ground rupture due to fault movement typically results in a relatively small percentage of the total damage in an earthquake, yet being too close to a rupturing fault can result in extensive damage. Secondary fault rupture refers to ground surface displacements along faults other than the main traces of Puente Hills Intermodal Facility Draft EIR City of Industry Page 5.4-3

4 active regional faults. Movement along these faults generally occurs in response to movement on a nearby regional fault. Secondary ground deformation includes fracturing, shattering, warping, tilting, uplift, and/or subsidence. Deformation and secondary faulting can also occur without primary ground rupture, as in the case of ground deformation above a blind (buried) thrust fault. Earthquake Fault Zones (known as Special Studies Zones prior to 1994) have been established in accordance with the Alquist-Priolo Special Studies Zones Act of The Act directs the State Geologist to delineate the regulatory zones that encompass surface traces of active faults that have a potential for future surface fault rupture. The purpose of the Alquist-Priolo Act is to regulate development near active faults in order to mitigate the hazard of surface fault rupture. The site is not located within an Alquist-Priolo Earthquake Fault Zone for fault surface rupture hazard. The surface traces of any active or potentially active faults are not known to pass directly through or project toward the site. Therefore, the potential for surface fault rupture at the site during the design life of the proposed development is considered low. Strong Seismic Ground Shaking The closest mapped active fault to the site is the Whittier fault, located approximately two miles to the southwest. During the past decade, researchers have speculated that low-angle thrust faults, capable of producing moderate to large earthquakes, may be present beneath the Los Angeles basin. The Puente Hills Blind Thrust and the Elysian Park Thrust are both located in close proximity to the PHIMF site. Table provides a list of the faults and fault systems within a 60-kilometer radius that are considered to contribute to the seismic exposure of the site. The estimated geoseismic characteristics of each fault are summarized in the table based on available published geologic and seismologic data. Due to the location of the project site within a region known to be seismically active, the project is required to adhere to design criteria as presented in the most recent California Building Code (CBC), including criteria for structures within Seismic Zone 4 and structures within five kilometers of a known active fault. Compliance with these seismic design criteria is a standard condition of all project approvals and would minimize seismic hazards to the extent feasible. In addition to these design considerations, the California Department of Transportation (Caltrans) has additional design parameters based on the maximum credible earthquake event from the Whittier-Elsinore fault and Elysian Park thrust. Based on the soil profile for the project site, Caltrans s ATC-32 report, Improved Seismic Design Criteria for Bridges, would apply. For improvements within the UPRR right-of-way, Federal Railroad Administration (FRA) and American Railway Engineering and Maintenance-of-Way Association (AREMA) seismic standards would also apply. Page The Planning Center December 2007

5 Table Faults and Fault Systems within 60 Kilometers of the Proposed PHIMF Maximum Fault Name Distance to PHIMF (km) Slip (mm/yr) Earthquake Magnitude (M w ) Type of Fault Whittier-Elsinore Strike Slip Puente Hills Thrust System Santa Fe Springs Segment Reverse Puente Hills Thrust System Coyote Hills Segment Reverse Puente Hills Thrust System Las Cienegas Segment Reverse Elysian Park Thrust Reverse Raymond Left Lateral Reverse Oblique San Jose Left Lateral Reverse Oblique Sierra Madre Reverse Clamshell Sawpit Reverse Verdugo Reverse Compton Thrust Reverse Hollywood Left Lateral Reverse Oblique Newport Inglewood (LA Basin) Strike Slip Chino Central Ave Right Lateral Reverse Oblique Cucamonga Reverse Santa Monica Left Lateral Reverse Oblique Palos Verdes Hills Strike Slip San Gabriel Stike Slip Elsinore Glen Ivy Strike Slip San Andreas - Mojave Strike Slip San Jacinto San Bernardino Strike Slip Source: KFM GeoScience Liquefaction and Related Ground Failure The entire project area is located within the Zone of Required Investigation for Liquefaction, as shown on the State of California Seismic Hazard Zones map, El Monte Quadrangle, issued in March Maps of seismic hazard zones are issued by CGS in accordance with the Seismic Hazards Mapping Act, ratified on April 1, Liquefaction of saturated soils can be caused by ground shaking during earthquakes. Research and historical data indicate that loose, relatively clean granular soils are susceptible to liquefaction and dynamic settlement, whereas the stability of the majority of clayey silts, silty clays, and clays is not adversely affected by ground shaking. Liquefaction typically occurs within the upper 50 feet of the surface, when saturated, loose, fine- to medium-grained soils (sand and silt) are present. Earthquake shaking suddenly increases pressure on the water that fills the pores between soil grains, causing the soil to lose strength and behave as a liquid. This process can be observed at the beach by standing on the wet sand near the surf zone. Standing still, the sand will support your weight. However, when you tap the sand with your feet, water comes to the surface, the sand liquefies, and your feet sink. When soils liquefy, the structures built on them can sink, tilt, and suffer significant structural damage. Liquefaction-related effects include loss of bearing strength, ground oscillations, lateral spreading, and flow Puente Hills Intermodal Facility Draft EIR City of Industry Page 5.4-5

6 failures or slumping. The excess water pressure is relieved by the ejection of material upward through fissures and cracks. A water-soil slurry bubbles onto the ground surface, resulting in features called sand boils, sand blows, or sand volcanoes. There are three general conditions that need to be met for liquefaction to occur: Strong ground shaking of relatively long duration Poorly consolidated granular sediments Water-saturated sediments within about 50 feet of the surface Strong ground shaking of relatively long duration can be expected to occur in the project vicinity as a result of an earthquake on any of several active faults in the region. The limited geotechnical study evaluated the liquefaction potential and seismically-induced dry settlement of the project site based on site-specific conditions. For depth to groundwater, analysis of liquefaction potential was conducted for both recent groundwater levels and historically high groundwater levels. Liquefaction potential of the proposed PHIMF project site and the existing PHMRF are shown in Table Table Liquefaction Potential Depth to Groundwater (feet bgs) Maximum Liquefaction Settlement (inches) Seismically Induced Dry Settlement (inches) Location Historical Groundwater Elevations (as presented by CGS) Boring to 0.5 PHIMF Near PHMRF southwest entrance Recent Groundwater Elevations PHIMF Near PHMRF southwest entrance Source: KFM GeoScience Boring Boring 3 5 Not Liquefiable 0 Boring Boring to 0.9 Boring 6 10 Not Liquefiable 0.2 to 0.9 Boring 1 43 Not Liquefiable 0.4 to 1.3 Boring 2 45 Not Liquefiable 0.2 to 0.6 Boring 3 43 Not Liquefiable 0.1 to 0.2 Boring 4 35 Not Liquefiable 0.2 to 0.3 Boring to 1.8 Boring 6 21 Not Liquefiable 0.4 to 2.3 Based on the results of the analysis, only a limited potential for localized liquefaction exists under recent groundwater conditions, but a relatively significant potential for liquefaction exists throughout the project site under historically high groundwater conditions. The soil boring taken at the PHMRF that exhibited the potential for liquefaction under recent groundwater conditions (Boring 5) is indicative of localized zones of liquefaction-susceptible materials throughout the local vicinity. The potential for seismically induced dry settlement of materials above recent groundwater levels ranges from 0.1 to 1.3 inches at the PHIMF site and from 0.4 to 2.3 inches at the PHMRF site. Page The Planning Center December 2007

7 Proposed Project Table presents construction aspects of the Preferred Access Option that require detailed geotechnical evaluation. PHMRF West Side of PHMRF Building & Storm Drain Reconfiguration Workman Mill Road Zee Medical (Parcel A) UPRR PHIMF Source: KFM GeoScience Table Key Geotechnical Components No Improvements 1) Open trench with walls retaining 0 to 18 feet. 2) Bridge over trench to access PHMRF and alley. 3) Storm drain reconfiguration (350 x 50 feet excavation 30 feet deep) 1) Embankment 0 to 4 feet high to raise grade and bridge over access corridor. 2) Open trench with side walls retaining 14 feet below existing grade. Open trench with walls retaining 14 feet to 18 feet high. Railroad bridge over trench 18 feet to 19 feet deep. Open trench with walls 0 to 18 feet Thresholds of Significance According to Appendix G of the CEQA Guidelines, a project would normally have a significant effect on the environment if the project would: G-1 Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: i) 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). ii) Strong seismic ground shaking. iii) Seismic-related ground failure, including liquefaction. iv) Landslides. G-2 Result in substantial soil erosion or the loss of topsoil. G-3 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 landslide, lateral spreading, subsidence, liquefaction or collapse. G-4 Be located on expansive soil, as defined in Table 18-1B of the Uniform Building Code (1994), creating substantial risks to life or property. G-5 Have soils incapable of adequately supporting the use of septic tanks or alternative waste water disposal systems where sewers are not available for the disposal of waste water. Puente Hills Intermodal Facility Draft EIR City of Industry Page 5.4-7

8 The Initial Study, included Appendix A in Volume IIA, substantiates that impacts associated with the following thresholds would be less than significant: Threshold G-1 (except for seismic-related ground failure, including liquefaction) Threshold G-2 Threshold G-5. These impacts will not be addressed in the following analysis Environmental Impacts The following impact analysis addresses thresholds of significance for which the Initial Study disclosed potentially significant impacts. The applicable thresholds are identified in brackets after the impact statement. IMPACT 5.4-1: THE PHIMF, PREFERRED ACCESS OPTION, AND UPRR RAIL CORRIDOR ARE LOCATED IN AN AREA SUSCEPTIBLE TO LIQUEFACTION AND SEISMICALLY INDUCED DRY SETTLEMENT AND WOULD REQUIRE SITE-SPECIFIC FIELD INVESTIGATION PRIOR TO GRADING ACTIVITIES. [THRESHOLDS G-1 (iii) AND G-3] Impact Analysis: As shown in the El Monte quadrangle of the State of California Seismic Hazard Zones map, released March 25, 1999, the majority of the PHIMF and the Union Pacific Railroad (UPRR) alignment are located within a zone subject to potential liquefaction hazards and seismically induced dry-settlement hazards. Analysis of the liquefaction potential and seismically induced dry-settlement hazards of the project site was conducted by KFM GeoScience and is shown in Table Based on the results of the analysis, only a limited potential for localized liquefaction exists under recent groundwater conditions. The majority of soil materials encountered in borings are deemed to possess limited potential for liquefaction. However, a soil boring drilled near the southwest entrance of the PHMRF encountered soils potentially susceptible to liquefaction, indicating that localized areas and zones of liquefaction-susceptible material could be present throughout the site. If historical high groundwater conditions were to occur, the potential for liquefaction at the project site would be significant. Based on current groundwater conditions, KFM GeoScience estimated that the potential for seismically induced dry settlement ranges from 0.1 to 2.3 inches. No field investigation was performed along the UPRR alignment, but based on a review of available documents it is likely that similar conditions to those observed at the PHMRF/PHIMF exist along the alignment. Additional investigation of the soil conditions at the PHIMF, along the Preferred Access Option, and along the UPRR right-of-way would be required to evaluate localized areas and zones of liquefaction susceptibility and seismically induced dry settlement. The effects of liquefaction may occur below the proposed bridge foundations, in the trench bottom, and outside the trench, and could result in increased loads on retaining structures and reduction in capacity of tieback bonds. IMPACT 5.4-2: CONSTRUCTION OF THE PREFERRED ACCESS OPTION WOULD REQUIRE RECONFIGURATION OF THE INDUSTRY PRIVATE DRAIN NO. 161, LINE A, IN CLOSE PROXIMITY TO THE GROUNDWATER TABLE. [THRESHOLD G-3] Impact Analysis: The highest groundwater elevation encountered along the Preferred Access Option alignment during various geotechnical investigations between 1974 and 2005 was approximately 223 feet above mean sea level (amsl). Based on review of the available geotechnical data and the well records from Page The Planning Center December 2007

9 the general project area, it is expected that groundwater level fluctuations within the foreseeable future will not substantially change the anticipated design conditions. The Preferred Access Option design indicates that the base of the trench would be at an elevation of 223 feet amsl at its deepest point. Therefore, the Preferred Access Option would not encroach into the groundwater table and dewatering or groundwater control would not be necessary. Construction of the Preferred Access Option would require reconfiguration of the existing San Jose Creek box culvert by widening the culvert to allow the top to be lowered while retaining the same flow capacity. The lowering of the box culvert profile is necessary to provide sufficient clearance for the access corridor to cross over the culvert and under Workman Mill Road. The elevation of the existing culvert flow line is approximately 223 feet amsl and the bottom of the culvert box is approximately 220 feet amsl. Therefore, reconfiguration of the box culvert would require excavation to an approximate elevation of 220 feet amsl, i.e., very close to or slightly into the groundwater. Consequently, a handling of localized seeps and nuisance water will likely be necessary. Additionally, the excavation would terminate in finer-grained alluvial deposits that would be susceptible to loosening and disturbance and may present difficulty for controlled excavation conditions. Consequently, additional measures would be necessary during construction to limit disturbance to the foundation soils at the excavation base. IMPACT 5.4-3: EXPANSIVE SOILS ARE NOT ANTICIPATED TO POSE A SIGNIFICANT RISK TO LIFE OR PROPERTY FOR THE PROPOSED PROJECT IMPROVEMENTS. [THRESHOLD G-4] Impact Analysis: Based on the proximity of the PHIMF and the rail improvements to the San Gabriel River and available Quaternary Geologic Mapping of the El Monte Quadrangle, soils within the project area are expected to consist of younger alluvial basin deposits composed of sand and silt with variable amounts of gravel and lean clay. The amount of clay contained in localized layers is expected to be relatively minor compared to the sand and silt fractions. Therefore, expansive soils conditions are not anticipated to pose a significant risk to life or property for the proposed improvements. Nevertheless, determination of expansion indices and chemical testing of the on-site materials would be required at the conclusion of rough grading to confirm that the soils are suitable for construction under the requirements of the Uniform Building Code Cumulative Impacts While potential geologic impacts associated with the project would be confined to the immediate project vicinity, construction of other planned or proposed projects in the vicinity of the site would cumulatively expose more people and structures to geotechnical constraints, such as earthquakes, expansive soils, landslides, and liquefaction. Adherence to Mitigation Measures contained in site-specific geotechnical reports, building codes, and grading ordinances would reduce geotechnical impacts to a level of less than significant at these individual project sites and, thus, no significant cumulative impact would occur Existing Regulations and Standard Conditions Alquist-Priolo Earthquake Fault Zoning Act. If a project site is located in an Earthquake Fault Zone (formerly known as Special Studies Zones), the City of Industry and the County of Los Angeles must withhold development permits for the site until geologic investigations demonstrate that the site is not threatened by surface displacement from future faulting, as required by the Alquist-Priolo Earthquake Fault Zoning Act, adopted by the state in The purpose of this Act is to regulate development near active faults so as to mitigate the hazard of surface fault rupture. Pursuant to this Act, structures for human occupancy are not allowed within 50 feet of the trace of an active fault. Puente Hills Intermodal Facility Draft EIR City of Industry Page 5.4-9

10 Seismic Hazard Mapping Act. The Seismic Hazard Mapping Act was adopted by the state in 1990 for the purpose of protecting public safety from the effects of strong ground shaking, liquefaction, landslides, or other ground failure caused by earthquakes. California Building Code (CBC) and Uniform Building Code (UBC). Development in the state is required to adhere to the building standards of the most recent CBC, which is included in Title 24 of the California Administrative Code, which incorporates the UBC. These codes provide minimum standards to protect property and the public welfare by regulating the design and construction of excavations, foundations, building frames, retaining walls, and other building elements to mitigate the effects of seismic shaking and adverse soil conditions. The procedures and limitations for the design of structures are based on site characteristics, occupancy type, configuration, structural system height, and seismic zoning for Seismic Zone 4. Seismic ratings are derived from UBC specifications, which divided the U.S. into four geographical zones, of which Zone 4 comprising most of central and coastal California was rated the most prone to earthquake activity. AREMA Standards. Design, construction and maintenance of railway infrastructure are required to adhere to the AREMA Standards, which include the Manual for Railway Engineering (Fixed Properties) and Trackwork Plans. These standards include guidelines for design, construction, and maintenance of ballast, ties, timber, concrete and steel structures, railway crossings, yards and terminals, track layout, and waterproofing Project Design Features No specific project design features are related to geology and soils Level of Significance Before Mitigation Upon implementation of regulatory requirements and standard conditions of approval, Impact would be less than significant. Without mitigation, the following impacts would be potentially significant: Impact The PHIMF, Preferred Access Option, and the UPRR rail corridor are located in an area susceptible to liquefaction and seismically induced dry settlement and would require site-specific field investigation prior to grading activities. Impact Construction of the Preferred Access option would require reconfiguration of the Industry Private Drain No. 161, Line A, in close proximity to the groundwater table Mitigation Measures Impact Site-specific geotechnical analysis shall be required for all proposed improvements to provide recommendations for fill material and compaction to ensure slope stability and reduce liquefaction and settlement potential. All formal grading plans and structural recommendations shall be reviewed and approved by appropriate agencies/stakeholders (e.g., the City of Industry Engineer, Los Angeles County Department of Public Works, and/or Union Pacific Railroad). Page The Planning Center December 2007

11 4-2 All grading and earthwork shall be performed under the oversight and supervision of a registered Geotechnical Engineer. Impact During subgrade preparation of the Industry Private Drain No. 161, Line A, reconfiguration associated with construction of the Preferred Access Option, the drainage system installed at the bottom of the excavation shall control nuisance water and localized seepage into the excavation. Open dewatering trenches or drains and sump pump systems shall be used for adequate drainage, as necessary. 4-4 During subgrade preparation of the Industry Private Drain No. 161, Line A, reconfiguration associated with construction of the Preferred Access Option, provisions shall be made for the overexcavation and replacement of disturbed or loosened material resulting from construction activity. Any loose and/or disturbed soil below the bearing area of the storm drain invert shall be removed and replaced with compacted fine concrete aggregate (concrete sand), aggregate base, or concrete. Concrete can be used as an alternative to compacted concrete aggregate. Such concrete shall satisfy the minimum requirements given for seal courses in Section 90 of Caltrans Standard Specifications. 4-5 During subgrade preparation of the Industry Private Drain No. 161, Line A, reconfiguration associated with construction of the Preferred Access Option, a working platform shall be established at the excavation bottom to protect against subgrade disturbance and to provide a platform for traffic and construction. The platform may be a granular base reinforced with geotextile. The granular working platform shall be constructed in accordance with recommended geotechnical design standards, such as those provided in the KFM GeoScience report of Level of Significance After Mitigation The Mitigation Measures above would reduce potential impacts associated with proposed improvements to the Puente Hills Intermodal Facility, Puente Hills Material Recovery Facility, the UPRR corridor, and the Preferred Access Option to a level that is less than significant. Therefore, no significant unavoidable adverse impacts related to geology and soils systems remain. Puente Hills Intermodal Facility Draft EIR City of Industry Page

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