GEOTECHNICAL EVALUATION REPORT COLLEGE BOULEVARD WIDENING PROJECT STUDY REPORT OCEANSIDE, CALIFORNIA

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1 GEOTECHNICAL EVALUATION REPORT COLLEGE BOULEVARD WIDENING PROJECT STUDY REPORT OCEANSIDE, CALIFORNIA PREPARED FOR: RBF Consulting 5050 Avenida Encinas, Suite 260 Carlsbad, California PREPARED BY: Ninyo & Moore Geotechnical and Environmental Sciences Consultants 5710 Ruffin Road San Diego, California October 20, 2008 (Revised October 30, 2008) Project No

2 October 20, 2008 (Revised October 30, 2008) Project No Ms. Dawn Wilson RBF Consulting 5050 Avenida Encinas, Suite 260 Carlsbad, California Subject: Geotechnical Evaluation Report College Boulevard Widening PSR Oceanside, California Dear Ms. Wilson: In accordance with your request and authorization, we have performed a geotechnical evaluation for the College Boulevard Widening Project Study Report in Oceanside, California. This report summarizes our findings and presents our conclusions and recommendations regarding the geotechnical aspects of the project study. Our study was conducted in accordance with the scope of services presented in our proposal for this project. We appreciate the opportunity to be of service. Sincerely, NINYO & MOORE Emily F. Lindstrum, P.G Project Geologist Jonathan Goodmacher, C.E.G Manager/Principal Geologist EFL/JG/kh Distribution: (1) Addressee (Electronic)

3 TABLE OF CONTENTS Page 1. INTRODUCTION SCOPE OF SERVICES PROJECT DESCRIPTION ENVIRONMENTAL SETTING Topography Geology Regional Geologic Setting Site Geology Groundwater Faulting and Seismicity Strong Ground Motion Ground Rupture Liquefaction and Seismically Induced Settlement Tsunamis Seismic Design Parameters Landsliding Expansive Soils Corrosive Soils REFERENCES...11 Tables Table 1 Principal Active Faults...6 Table 2 Historical Earthquakes that Affected the Site...6 Table 3 Seismic Design Factors...9 Figures Figure 1 Site Location Map Figure 2 Project Study Area Figure 3 Geologic Map Figure 4 Fault Location Map i

4 1. INTRODUCTION In accordance with your request, Ninyo & Moore has performed a Geotechnical Evaluation for the College Boulevard Widening Project. This report presents our preliminary findings and conclusions pertaining to the proposed project. The purpose of this study was to evaluate geologic and geotechnical conditions through reconnaissance observations and available pertinent data to provide a Geotechnical Evaluation report. We understand that our report will be used as part of Project Study Report (PSR). Subsurface exploration and laboratory testing of materials were not included in the scope of this preliminary evaluation. 2. SCOPE OF SERVICES Ninyo & Moore s scope of services included the following tasks: Review of pertinent available geologic and geotechnical reports and literature including the following: Topographic maps, Geologic maps, Fault hazard maps prepared by the State of California, Stereoscopic aerial photographs, and Readily available geologic reports. Performance of a geologic reconnaissance of the project study area to document readily apparent geotechnical, geologic, and soils conditions. Compilation and analysis of the data obtained. Preparation of this report presenting our findings and conclusions related to geologic and geotechnical conditions at the site, and potential geologic and geotechnical constraints for the development of the proposed project. 3. PROJECT DESCRIPTION According to the March 10, 2008, Request for Proposals for Project Study Report (PSR) to Widen College Boulevard between Waring Road and Old Grove Road, prepared by the City of Oceanside, College Boulevard is located within the easterly portion of the City of Oceanside. Figure 1 is a map 1

5 showing the general location of the project. College Boulevard is currently a north-south, four-lane major arterial. After widening it will be a six-lane arterial. Per the Request for Proposals the project has been separated into three sections as follows: Section 1- Extends from Waring Road approximately 800 feet north to Roselle Street. Section 2- Extends north from Roselle Street 800 feet north to Thunder Drive. Section 3- Extends from Thunder Drive north to Old Grove Road. The project area is currently developed for a mix of residential and retail/commercial uses. In addition other development in the area includes railroad tracks associated with the North County Transit District (NCTD) right-of-way crossing (in Section 3). Loma Alta Creek crosses under College Boulevard immediately to the north the NCTD tracks in Section 3. An unnamed creek crosses in Section 2. Figure 2 is an aerial photograph depicting the features outlined and the approximate locations of the boundaries of each of the project sections discussed. 4. ENVIRONMENTAL SETTING The following sections include discussions of the topographic, geologic, and hydrogeologic conditions at the site. Included are analyses of faulting and seismicity; liquefaction and seismic settlement; landslides; and expansive and corrosive soils. Our evaluation is based on reviews of published and unpublished reports, aerial photographs, in-house data, reconnaissance observations, and the assessment of potential geologic hazards and geotechnical constraints Topography Based on a review of the United States Geological Survey (USGS) San Luis Rey Topographic Quadrangle Map (USGS, 1975), ground elevations across the project vary in elevation from approximately 220 feet to 420 feet above mean seal level (MSL). A discussion of the topography of each section is presented below. Section 1 - Topographically, College Boulevard ascends throughout this section of the project from Waring Road to the north. Elevations in this section vary from approximately 220 feet at the south end of the project (Waring Road) to approximately 370 feet near Roselle Road. 2

6 Section 2 - Topographically, College Boulevard generally ascends throughout this section of the project from Roselle Road to the north. Elevations in this section vary from approximately 370 feet at Roselle Road to approximately 390 feet near Thunder Road. Section 3 - Topographically, College Boulevard descends from Thunder Road to its crossing of Loma Alta Creek. From Loma Alta Creek it ascends again to its northern end at Old Grove Road. Elevations in this section vary from approximately 220 feet near Loma Alta Creek to approximately 420 feet near Old Grove Road Geology The following sections present our findings relative to regional geology, site geology, groundwater, and faulting and seismicity. Figure 3 is a map showing the geology of the site as mapped by Kennedy and Tan (2005) Regional Geologic Setting The project area is situated in the coastal foothill section of the Peninsular Ranges Geomorphic Province. This geomorphic province encompasses an area that extends approximately 900 miles from the Transverse Ranges and the Los Angeles Basin south to the southern tip of Baja California (Norris and Webb, 1990; Harden, 1998). The province varies in width from approximately 30 to 100 miles. In general, the province consists of rugged mountains underlain by Jurassic metavolcanic and metasedimentary rocks, and Cretaceous igneous rocks of the southern California batholith. The Peninsular Ranges Province is traversed by a group of sub-parallel faults and fault zones trending roughly northwest. Several of these faults, which are shown on Figure 4, are considered active faults. The Elsinore, San Jacinto, and San Andreas faults are active fault systems located northeast of the project area and the Rose Canyon-Newport- Inglewood, Agua Blanca-Coronado Bank, and San Clemente faults are active faults located west of the project area. Major tectonic activity associated with these and other faults within this regional tectonic framework consists primarily of right-lateral, strikeslip movement. Further discussion of faulting relative to the site is provided in the Faulting and Seismicity section of this report. 3

7 Site Geology From our geologic reconnaissance of the project area, in conjunction with review of available geologic mapping and reports the site is underlain by surficial topsoil and colluvium, fills (both documented and undocumented), Quaternary Alluvial Floodplain Deposits, Quaternary Landslides, and materials of the Tertiary-aged Santiago Formation (Figure 3). Generalized descriptions of the geologic units described are presented below Fills Based on our experience in similar urbanized settings the presence of documented and undocumented fills should be expected. Fills soils are typically placed in these areas to create a level pad for construction of improvements Alluvial flood plain deposits Per Kennedy and Tan (2005) the alluvial flood plain deposits are comprised of active and recently active alluvial deposits along canyon floors. These deposits are expected to consist generally of unconsolidated, sandy, silty or clayey materials Landslide deposits Landslide deposits are mapped in Section 3 of the project study area (Tan and Giffen, 1995; Kennedy and Tan, 2005). Specifically, these deposits are mapped on the south side of the Loma Alta Creek drainage basin. Per Kennedy and Tan (2005), these Quaternary deposits are highly fragmented to largely coherent and range from unconsolidated to moderately well consolidated. Many Pleistocene-age landslides were reactivated in part or entirely during late Holocene Santiago Formation Per Kennedy and Tan (2005) the Santiago Formation is Eocene in age. Depending on location there are three distinct members of this unit. These are a basal member that consists of buff and brownish-gray, massive, coarse-grained, poorly sorted arkosic sand- 4

8 stone and conglomerate (sandstone generally predominating). In some areas the basal member is overlain by gray and brownish-gray (salt and pepper) central member that consists of soft, medium-grained, moderately well-sorted arkosic sandstone. An upper member consists of gray, coarse-grained arkosic sandstone and grit. Throughout the formation, both vertically and laterally, there exists greenish-brown, massive claystone interbeds, tongues and lenses of often fossiliferous, lagoonal claystone and siltstone. Most areas of the project are covered with vegetation or construction and exposures of the geologic materials are sparse. However, we were able to evaluate structural attitudes at the locations in Section 2. At those locations out-of-slope conditions were not observed Groundwater Based on the reviewed State Water Resources Control Board (SWRCB) GeoTracker website, groundwater is present in the project area (the intersection of College Boulevard of Oceanside Boulevard) at depths of less than 5 feet below ground surface (GeoTracker, 2008). The general direction of groundwater flow is expected to be to the west toward the Pacific Ocean. However, at some project locations the groundwater flow direction should generally be expected to be toward the nearest creek. Groundwater levels and flow directions are anticipated to vary at different locations on the site. Groundwater levels can fluctuate due to seasonal variations, groundwater withdrawal or injection, and other factors. The depth of groundwater should be further evaluated through site-specific subsurface evaluation during the design phase of the project Faulting and Seismicity As discussed earlier, like most of southern California, the project area is considered to be seismically active. Based on our review of the referenced geologic maps and stereoscopic aerial photographs, as well as on our geologic field mapping, the subject site is not underlain by known active or potentially active faults (i.e., faults that exhibit evidence of ground displace- 5

9 ment in the last 11,000 years and 2,000,000 years, respectively). The nearest known active fault is the offshore segment of the Rose Canyon-Newport-Inglewood Fault, located approximately 8 miles west of the site (Figure 4). Table 1 lists selected principal known active faults that may affect the subject site, the maximum moment magnitude (M max ) and the fault types as published for the California Geological Survey (CGS) by Cao et al. (2003). The approximate fault to site distance was calculated by the computer program FRISKSP (Blake, 2001). Fault Table 1 Principal Active Faults Approximate Distance miles (kilometers) 1,2 Moment Magnitude (M W ) 2 Rose Canyon-Newport-Inglewood (Offshore) 8 (13) 7.2/B Elsinore (Temecula Segment) 21 (34) 7.1/A Elsinore (Julian Segment) 21 (34) 7.1/A Coronado Bank 24 (39) 7.6/B Elsinore (Glen Ivy Segment) 32 (51) 7.1/A San Jacinto (Coyote Creek Segment) 50 (82) 6.8/A Notes: Blake (2001) 2 Cao, et al. (2003) In general, hazards associated with seismic activity include strong ground motion, ground surface rupture, liquefaction, seismically induced settlement, and tsunamis. These hazards are discussed in the following sections Strong Ground Motion Based on our review of background information, data pertaining to the historical seismicity of the San Diego area are summarized in Table 2 below. This table presents historic earthquakes within a radius of approximately 62 miles (100 kilometers) of the site with a magnitude of 6.0 or greater. Table 2 Historical Earthquakes that Affected the Site Date Magnitude Approximate Epicentral Distance (M) miles (kilometers) November 22, (39) February 9, (89) February 24, (61) 6

10 Table 2 Historical Earthquakes that Affected the Site Date Magnitude Approximate Epicentral Distance (M) miles (kilometers) May 28, (82) March 25, (93) October 21, (90) March 19, (89) April 9, (87) November 24, (94) A site-specific probabilistic seismic hazard analysis was performed to evaluate anticipated peak ground accelerations (PGAs) for the site using the computer program FRISKSP developed by Blake (2001). A probabilistic analysis incorporates uncertainties in time, recurrence intervals, size, and location (along faults) of hypothetical earthquakes. This method thus accounts for likelihood (rather than certainty) of occurrence and provides levels of ground acceleration that might be more reasonably hypothesized for a finite exposure period. FRISKSP calculates the probability of experiencing various ground accelerations at a site over a period of time and the probability of exceeding expected ground accelerations within the lifetime of the proposed structure from the significant earthquakes within a specific radius of search. For the present case, a search radius of 62 miles (i.e., 100 kilometers) was selected. The earthquake magnitudes used in this program are based on the current CGS fault model. The 2007 California Building Code (CBC) recommends that the design of structures be based on the horizontal PGA having a 2 percent probability of exceedance in 50 years which is defined as the Maximum Considered Earthquake (MCE). The statistical return period for PGA MCE is approximately 2,475 years. This indicates that an earthquake capable of causing shaking in the area (to approximately 1/3 the value of gravity) will occur once every 2,475 years. In evaluating the seismic hazards associated with the subject site, we have used an attenuation relation proposed by Boore, et al. (1997) for Soil Type D with an average shear wave velocity of about 800 feet per second (i.e., 250 meters per second). The PGA MCE for the site was calculated as 0.32g (approximately 1/3 the value of gravity). This estimate of ground motion does 7

11 not include near-source factors that may be applicable to the design of structures on site. The nature and depth of soil materials should be further evaluated through site-specific subsurface and laboratory evaluation during the design phase of the project Ground Rupture There are no known active faults crossing the subject site, and the potential for ground rupture due to faulting is considered low. Surface ground cracking related to shaking from distant events is not considered a significant hazard, although it is a possibility Liquefaction and Seismically Induced Settlement Liquefaction of cohesionless soils can be caused by strong vibratory motion due to earthquakes. Research and historical data indicate that loose granular soils and non-plastic silts that are saturated by a relatively shallow groundwater table are susceptible to liquefaction. Portions of the project area (in the lower parts of the drainages of Loma Alta and the unnamed creek) are dominantly underlain by alluvial deposits with a relatively shallow groundwater table. Based on this information, the potential for liquefaction and seismically induced settlement at the site is considered moderate to high in the drainage basin bottoms and low in areas underlain by the Santiago Formation. The potential for liquefaction should be further evaluated through site-specific subsurface and laboratory evaluation during the design phase of the project Tsunamis Tsunamis are long wavelength seismic sea waves (long compared to the ocean depth) generated by sudden movements of the ocean bottom during submarine earthquakes, landslides, or volcanic activity. Based on the inland location of the site, the potential for a tsunami to affect the site is not a design consideration Seismic Design Parameters Design of the proposed improvements should comply with design for structures located in Seismic Zone 4 and should be designed in accordance with the requirements of governing 8

12 jurisdictions and applicable building codes. Table 3 presents the seismic design parameters for the site in accordance with CBC International Building Code (IBC) guidelines (2007) guidelines and mapped spectral acceleration parameters (USGS, 2007). The nature and depth of soil materials should be further evaluated through site-specific subsurface and laboratory evaluation during the design phase of the project. Table 3 Seismic Design Factors Factors Values Site Class D Site Coefficient, F a Site Coefficient, F v Mapped Short Period Spectral Acceleration, S S 1.122g Mapped One-Second Period Spectral Acceleration, S g Short Period Spectral Acceleration Adjusted For Site Class, S MS 1.179g One-Second Period Spectral Acceleration Adjusted For Site Class, S M g Design Short Period Spectral Acceleration, S DS 0.786g Design One-Second Period Spectral Acceleration, S D g 4.5. Landsliding Based on our review of published geologic maps (Tan and Giffen, 1995) and as shown on Figure3, landslides are mapped at the project site (in Area 3) and in the project vicinity. Based on the variable topography of the project site the potential for landslides at the site is low to moderate. The presence and extent of landslides should be further evaluated by subsurface and laboratory evaluation once project designs are confirmed Expansive Soils Expansive soils are soils that undergo volumetric change with change in water content. The soil will swell with increase in moisture content and will shrink with decrease in moisture content. Soils with high shrink-swell potential generally contain high percentages of certain clay minerals and can cause extensive damage to structures and improvements. As noted, geologic deposits at the site are anticipated to consist of fill, alluvial and landslide deposits, and units of the Santiago Formation. According to the reviewed geologic maps, silty to 9

13 clayey soil materials are present in the alluvial, landslide, and Santiago Formation materials. Silty to clayey soils may range from moderately to highly expansive as defined by American Society for Testing and Materials (ASTM) D The presence and extent of expansive soils should be further evaluated by subsurface and laboratory evaluation. Potential mitigation measures for expansive soils may include removal or deep burial during grading, moisture conditioning, or specially designed foundations and slabs Corrosive Soils As noted, geologic deposits at the site are anticipated to consist of fill, alluvial and landslide deposits, and units of the Santiago Formation. Based on our experience in the project are these soils may be expected to be corrosive. The presence and extent of potentially corrosive soils should be further evaluated by subsurface and laboratory evaluation. Potential mitigation measures for corrosive soils may include engineering controls. 10

14 5. REFERENCES Blake, T.F., 2001a, FRISKSP (ver 4.00) A Computer Program for the Probabilistic Estimation of Peak Acceleration and Uniform Hazard Spectra Using 3-D Faults as Earthquake Sources. Boore, D.M., Joyner, W.B., and Fumal, T.E., 1997, Equations for Estimating Horizontal Response Spectra and Peak Acceleration from Western North American Earthquakes: A Summary of Recent Work, Seismological Research Letters, Vol. 68, No. 1, pp California Department of Conservation, Division of Mines and Geology, 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in California, CDMG Special Publication 117. California Geological Survey (CGS), 1998, Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada: International Conference of Building Officials. California Geological Survey (CGS), 2003, Probabilistic Seismic Hazard Assessment Maps (PSHA), World Wide Web, California Geological Survey, 2006, Seismic Shaking Hazards in California, last edited on October 30. California Department of Transportation (Caltrans), 2006, Corrosion Guidelines, Version 1.0, Division of Engineering Services, Materials Engineering and Testing Services, Corrosion Technology Branch: dated September. California Department of Water Resources (DWR), 2008, Water Data Library Website, accessed in September. California State Water Resources Control Board, 2008, GeoTracker Website, accessed in September. Cao, T., Bryant, W. A., Rowshandel, B., Branum, D., and Willis, C. J., 2003, The Revised 2002 California Probabilistic Seismic Hazards Maps: California Geological Survey: dated June. City of Oceanside, 2008, Request for Proposals for Project Study Report (PSR) to Widen College Boulevard between Waring Road and Old Grove Road, dated March 10. Google, Inc., 2006, Hart, E.W., and Bryant, W.A., 1997, Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps: California Department of Conservation, Division of Mines and Geology, Special Publication 42, with Supplements 1 and 2 added in Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, California Geologic Data Map Series, Map No. 6, Scale 1:750,

15 Kennedy, M.P., and Tan, S.S., 2005, Geologic Map of the Oceanside 30 x 60 Quadrangle, Oceanside, California, Scale 1:100,000. Ninyo & Moore, In-house proprietary information. Norris, R.M., and Webb, R.W., 1990, Geology of California: John Wiley & Sons, pp Peterson, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., 1996, Probabilistic Seismic Hazard Assessment for the State of California: California Department of Conservation Division of Mines and Geology Open File Report 96-08, and United States Department of the Interior United States Geological Survey Open File Report Tan, S.S. and Giffen, D.G., 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San Diego County, California, Landslide Hazards Identification Map No. 35: DMG OFR United States Geological Survey (USGS), 2000, Earthquake History 1769 Present, California, Nevada, and Baja California, World Wide Web, United States Geological Survey, 1975, San Luis Rey Quadrangle, California, San Diego County, 7.5-Minute Series (Topographic): Scale 1:24,000. Wesnousky, S.G., 1986, Earthquakes, Faults, and Seismic Hazards in California: Journal of Geophysical Research, Vol. 91, No. B12. Youd, T.L., and Idriss, I.M. (Editors), 1997, Proceedings of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils, Salt Lake City, Utah, January 5 through 6, 1996, NCEER Technical Report NCEER , Buffalo, New York. 12

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17 OLD GROV E ROAD APPROXIMATE SECTION 3 BOUNDARY OCEANSIDE BOULEVARD SDNR OLIVE DRIVE SITE THUNDER DRIVE MARVIN STREET APPROXIMATE SECTION 2 BOUNDARY ROSELLE AVENUE APPROXIMATE SECTION 1 BOUNDARY WARING ROAD W. VISTA WAY SOURCE: TERRASERVERAERIAL IMAGE, VERTICAL MAPPING RESOURCES, INC. 78 ± N 1, ,800 NOTE: ALL DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE APPROXIMATE SCALE IN FEET PROJECT STUDY AREA FIGURE PROJECT NO. DATE /08 COLLEGE BOULEVARD WIDENING PROJECT OCEANSIDE, CALIFORNIA 2

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