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Home My WebLink About103635-01; El Camino Real-Recon; El Camino Real Widening; 2008-01-04I I I I I I I I I I I I I I I I I I Geotechnical and Environmental Sciences Consultants LIMITED GEOTECHNICAL EVALUATION EL CAMINO REAL WIDENING PROJECT CARLSBAD, CALIFORNIA D 2 1 1998 ENGINEERING DEPARTMENT PREPARED FOR: RECON 4241 Jutland Drive, Suite 201 San Diego, California 92117 PREPARED BY: Ninyo & Moore Geotechnical and Environmental Sciences Consultants 10225 Barnes Canyon Road, Suite A-112 San Diego, California 92121 June 4, 1998 Project No. 103635-01 10225 Barnes Canyon Road • Suite A-M 2 • San Diego, California 92 1 21 • Phone (619) 457-0400 • Fax (6I9J 558-1236 Oakland [510)893-2551 Irvine (714)472-5444 Los Angeles (213)488-511 Ontario (909) 947-1588 Las Vegas (702) 433-0330 June 4, 1998 Project No. 103635-01 Mr. Tom Held RECON 4241 Jutland Drive, Suite 201 San Diego, California 92117 Subject: Limited Geotechnical Evaluation El Camino Real Widening Project Carlsbad, California Dear Mr. Held: Transmitted herein are the results of Ninyo & Moore's limited geotechnical evaluation for the El Camino Real Widening project. This study was conducted in accordance with your request and included review and analysis of available geologic and geotechnical background data, and a geo- logic reconnaissance of the project site area. We understand that the results of this study will be utilized in the preparation of environmental impact documents. We appreciate the opportunity to be of service. Should you have any questions or comments re- garding this report, please contact the undersigned at your convenience. Respectfully submitted, NINYO & MOORE Gregory T. Farrand; Principal Geologist RDH/RI/GTF/MRR/ccl Distribution: (4) Addressee Michael R. Rahilly, RCE, GE Chief Geotechnical Engineer RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 TABLE OF CONTENTS Page 1. INTRODUCTION 1 2. SCOPE OF SERVICES 1 3. SITE DESCRIPTION 1 4. PROJECT DESCRIPTION 2 5. GEOLOGY 3 5.1. Regional Geologic Setting 3 5.2. Site Geology 4 5.2.1. Artificial Fill 4 5.2.2. Alluvium 4 5.2.3. Santiago Formation 4 5.3. Groundwater 5 5.4. Faulting and Seismicity 5 5.4.1. Strong Ground Motion and Ground Surface Rupture 6 5.4.2. Liquefaction and Seismically Induced Settlement 6 5.4.3. Tsunamis 7 5.5. Agricultural Soils 7 5.6. Mineral Resources 7 6. CONCLUSIONS 8 6.1. Geologic and Geotechnical Constraints and Possible Mitigation Measures 8 7. LIMITATIONS 9 8. SELECTED REFERENCES 10 Illustrations Figure 1 - Site Location Map Figure 2 - Topographic Map Figure 3 - Fault Location Map Table Table 1-Seismic Parameters for Maximum Credible Earthquakes 12 3635-0 leir-doc RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 1. INTRODUCTION In accordance with your request, Ninyo & Moore has performed a geologic reconnaissance and limited geotechnical evaluation of the project site. The purpose of this study was to evaluate geologic and geotechnical conditions using available geologic and geotechnical data and to pro- vide a geotechnical reconnaissance report, which we understand will be utilized in the preparation of environmental impact documents. This report presents our preliminary findings and conclusions pertaining to the proposed El Camino Real widening project. Subsurface exploration and labora- tory testing of materials were hot included in the scope of this limited evaluation. 2. SCOPE OF SERVICES Ninyo & Moore's scope of services has included review of background materials, and geologic reconnaissance of the site area. Specifically, we have performed the following tasks: • Review of pertinent, available geotechnical literature including topographic maps, geologic maps, stereoscopic aerial photographs, and geotechnical and geologic reports. Documents pertaining to the site vicinity, as well as documents reviewed for our site evaluation are listed in the Selected References section of this report. • Geologic reconnaissance and mapping of the project study area, which included written and photographic documentation of the observed site conditions. These materials are on file at the offices of Ninyo & Moore and are available for review upon request. • Compilation and analysis of the data obtained. • Preparation of this report to present our preliminary findings and conclusions, particularly, re- garding potential geotechnical constraints and possible mitigative measures. 3. SITE DESCRIPTION The site consists of an approximately 1,200-foot long section of El Camino Real (approximately station 441+00 to 453+00), approximately 2!/2 miles northwest of Palomar Airport Road in the city of Carlsbad (see Figure 1). El Camino Real is currently a four-lane roadway, with a paved section that is approximately 100-feet wide. In the project area, the roadway is located on a fill embankment that ranges from seven to ten feet in height above the surrounding floodplain of 3635-01eir.doc RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 Agua Hedionda Creek. From Station 441+70 to Station 442+83, El Camino Real crosses Agua Hedionda Creek via a concrete bridge. The bridge is 113-feet long and 108 feet wide and is sup- ported at two bents within the creek channel and two abutments. According to a report dated January 15, 1997, prepared by Agra Earth and Environmental, Inc., the foundation of the bridge consists of 14 Class XI piles at each abutment and bent. The AGRA report indicates that the piles may be either precast, prestressed concrete piles or step-taper steel shells (Raymond Step-Taper Piles) filled with concrete. The exposed portions of the piles at the bents are 16-inch diameter concrete columns. Elevations across the site range from approximately 45.8 feet above mean sea level (MSL) near the center of the bridge to roughly 29 feet within the Agua Hedionda Creek channel, west of the bridge. A topographic map is provided as Figure 2. Vegetation consists of moderate to dense na- tive growth along the sides of the creek channel and within the floodplain west of the road. Agricultural land exists on the north side of El Camino Real, northwest of the bridge. A trailer park development exists on the north side of El Camino Real, northeast of the bridge. 4. PROJECT DESCRIPTION We understand that the proposed development will consist of the widening of El Camino Real from approximately Station 441+00 to approximately Station 453+00 (roughly 1,200 feet). The widening includes the addition of one lane on each side, widening the existing bridge over Agua Hedionda Creek by two feet on each side for sidewalks, and the addition of a right-turn lane from southbound El Camino Real to (future) westbound Cannon Road. Based on review of the project plans, additions to the existing bridge foundations are not planned. The proposed Cannon Road will cross El Camino Real approximately 75 feet north of the existing bridge. Cannon Road will cross Agua Hedionda Creek via a proposed bridge to be located approximately 150 feet south- west of the existing El Camino Real bridge. 363S-01eir.DOC RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 5. GEOLOGY The following sections present our findings relative to regional geology, site geology, groundwa- ter, faulting and seismicity, agricultural soils, and mineral resources. 5.1. Regional Geologic Setting The project study area is situated in the western portion of the Peninsular Ranges geomorphic province of southern California. This geomorphic province encompasses an area that extends 125 miles, from the Transverse Ranges and the Los Angeles Basin, south to the Mexican border, and beyond another 775 miles to the tip of Baja California (Norris and Webb, 1990). The geomorphic province varies in width from 30 to 100 miles, most of which is character- ized by northwest trending mountain ranges separated by subparallel fault zones. In general, the Peninsular Ranges are underlain by Jurassic-age metavolcanic and metasedimentary rocks and by Cretaceous-age igneous rocks of the southern California batholith. The westernmost portion of the province in San Diego County, in which the site is located, generally consists of Upper Cretaceous-, Tertiary-, and Quaternary-age sedimentary rocks. The Peninsular Ranges are traversed by several major active faults (Figure 3, Fault Location Map). The Whittier-Elsinore, San Jacinto, and the San Andreas faults are major active fault systems located northeast of the site and the Agua Blanca-Coronado Bank and San Clemente faults are active faults located to the west-southwest. The Rose Canyon fault zone is also a major fault system, located offshore of Carlsbad, portions of which have recently been recog- nized as active by the State of California. Major tectonic activity associated with these and other faults within this regional tectonic framework is right-lateral strike-slip movement. These faults, as well as other faults in the region, have the potential for generating strong ground motions at the project site. Further discussion of faulting relative to the site is pro- vided in the Faulting and Seismicity section of this report. 3635-0 leir.doc RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 5.2. Site Geology Based on our literature review, including published geologic maps and available geotechnical reports, the project site is underlain generally by artificial fill, alluvium, and formational mate- rials of the Santiago Formation. A brief description of these units, as described in the cited literature, or as observed on the site, is presented below. 5.2.1. Artificial Fill Previous construction along and adjacent to El Camino Real has resulted in the place- ment of artificial fill. Based on review of previous geotechnical reports and topographic maps, these fill soils are expected to be up to roughly 10 feet deep along the existing roadway. These soils consist generally of clayey sands and silty sands. In addition to these soils, riprap composed of boulder-sized rocks locally line the abutments of the ex- isting bridge. 5.2.2. Alluvium Recent alluvial deposits underlie the fill soils. The alluvium was within the floodplain of Agua Hedionda Creek. Based on the previous geotechnical reports, the alluvium is de- scribed as soft to stiff silty clay and loose to medium dense silty sand. The alluvium is expected to be greater than 100 feet deep in the project vicinity. 5.2.3. Santiago Formation Materials of the Eocene-age Santiago Formation underlie the alluvium in the project area. The Santiago Formation is described as very dense, silty sandstone and interbedded hard claystone. Based on our review of published geologic maps and stereoscopic aerial photographs, as well as our site reconnaissance, no landslides or faults were observed at the project site. Active faulting, however, has been mapped in the site region and could potentially impact 3635-01 eirdoc RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 the proposed redevelopment. A more detailed discussion of faulting and seismicity is presented in the Faulting and Seismicity section of this report. 5.3. Groundwater Based on our site reconnaissance and review of previous geotechnical reports, the depth to groundwater is expected to occur at a depth of approximately 10 to 15 feet below the exist- ing road grade. The depth to groundwater may be at or near the ground surface within Agua Hedionda Creek. At the time of our site visit, on May 5, 1998, there was a moderate flow of water within Agua Hedionda Creek. The depth to groundwater at the site may fluctuate with seasonal variations and perched conditions may be locally present. 5.4. Faulting and Seismicity The project site is considered to be in a seismically active area, as is most of southern Cali- fornia. Based on our review of the referenced reports, geologic maps, and stereoscopic aerial photographs, as well as on our geologic field mapping, the project site is not underlain by known active fault splays (i.e., faults that exhibit evidence of ground displacement during the last 11,000 years). The Rose Canyon fault zone has been mapped approximately 4 miles to the west. The Rose Canyon fault zone is the onshore portion of a more extensive fault zone that includes the Offshore Zone of Deformation and the Newport-Inglewood fault to the north, and several possible extensions southward, both onshore and offshore (Treiman, 1993). The Rose Canyon fault zone is made of predominantly right-lateral strike-slip faults that extend south-southeast through the San Diego metropolitan area. Various fault strands display strike-slip, normal, oblique, or reverse components of displacement (Treiman, 1993). The fault zone extends offshore at La Jolla and continues north-northwest subparallel to the coastline. Portions of the Rose Canyon fault zone in the Rose Canyon, Mission Bay, and downtown areas of San Diego have recently been recognized by the State of California as active (CDMG, 1991). M35-01w.doc Ninya RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 Table 1 summarizes the significant faults that may affect the project site, distances to major active faults within 62 miles (100 kilometers) of the subject site, and anticipated horizontal ground accelerations at the site that may be generated as a result of Maximum Credible Earthquakes along these faults. The approximate locations of nearby major faults relative to the site are shown on Figure 3. In general, hazards associated with seismic activity include strong ground motion, ground surface rupture, liquefaction, seismically induced settlement, and tsunamis. These potential hazards are discussed in the following sections. 5.4.1. Strong Ground Motion and Ground Surface Rupture Based on the Maximum Credible earthquake (MCE) magnitudes for faults listed in Ta- ble 1, and on the distances between the study area and these faults, it is our opinion that the most significant MCE with respect to the site would be an earthquake of magnitude 7.0 on the Rose Canyon fault zone. Attenuation curves published by Mualchin and Jones (1992) and seismic research performed by Ploessel and Slosson (1974) indicate that the predicted peak horizontal bedrock acceleration from a magnitude 7.0 earthquake on the Rose Canyon fault zone would be approximately 0.45g (45 percent of gravity), with a repeatable high ground acceleration of approximately 0.29g. Based on our review of the referenced literature, no active faults have been mapped across the project site. Based on the absence of mapped active faults on or in proximity to the site, the potential for ground surface rupture at the subject site is considered low. Lurching or cracking of the ground surface as a result of nearby seismic events is possi- ble. 5.4.2. 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- 3635-01eir.doc RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 plastic silts that are saturated by a relatively shallow groundwater table are most suscep- tible to liquefaction. Our evaluation has indicated that the project site is underlain by soft to stiff clay and loose to medium dense sandy alluvium with a near-surface groundwater table. Based on the presence of these conditions and the possible seismic accelerations, the potential for liquefaction and seismically induced settlement in the project area, is considered moder- ate. 5.4.3. Tsunamis Tsunamis are long 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 location of the site, approximately 21A miles east of the coastline, the potential for damage due to tsunami is considered very low. 5.5. Agricultural Soils From an agricultural perspective, prior to grading, the site was underlain by Salinas clay loam and river wash (USDA, 1973). The earlier development of the site has resulted in grading that has removed or buried the original soil profile. Accordingly, the proposed project will not result in the additional loss of agricultural soils. 5.6. Mineral Resources Our evaluation has indicated that no significant economic mineral resources have been dis- covered within the limits of the project study area. Therefore the potential for loss of mineral deposits due to further development of the study area is considered low. 363S-Qleir.DOC RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 6. CONCLUSIONS Based on the results of our geologic reconnaissance and limited geotechnical evaluation, it is our opinion that construction of the project is feasible from a geotechnical perspective. Based on our review of geotechnical reports by others, published geologic maps and aerial photographs, and our site reconnaissance, no active faults or landslides have been mapped or were observed within the study area. However, the Rose Canyon fault zone is located approximately 4 miles to the west of the site. We recommend that a comprehensive geotechnical evaluation, including development-specific subsurface exploration and laboratory testing be conducted prior to design and construction. The purpose of the subsurface evaluation would be to further evaluate the subsurface conditions in the area of the proposed structures and to provide information pertaining to the engineering charac- teristics of earth materials at the project site. From these data, recommendations for grading/earthwork, surface and subsurface drainage, foundations, pavement structural sections, and other pertinent geotechnical design considerations may be formulated. 6.1. Geologic and Geotechnical Constraints and Possible Mitigation Measures In our opinion, the following geotechnical factors should be considered in the planning and implementation of the project: • The road widening may impose additional loads on the existing fill and alluvial soils that may induce unacceptable settlement. The potential for excessive settlement of fill and/or alluvial soils may be addressed by subsurface evaluation and laboratory testing. To miti- gate settlement, the existing soils may be reworked and compacted during grading prior to construction of the proposed improvements. • The presence of loose, granular soils and the shallow depth of groundwater within the existing Agua Hedionda Creek increases the potential of liquefaction and dynamic set- tlement occurring in the event of strong ground shaking at the site. Mitigation measures for liquefiable soils include ground modification (such as removal and recompaction of loose soils) or the use of deep foundations. It was not clear in the AGRA report if lique- faction of the Agua Hedionda Creek soils was addressed or if the existing piles were designed to mitigate the effects of liquefaction. Additional evaluation should be consid- ered. 3635-Oleir.DOC tyinyo RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 Based on the data presented in Table 1, the potential for strong ground motions to occur at the site is significant. In addition, western San Diego County, including the site area, has been upgraded to Seismic Zone 4 in the 1994 edition of the Uniform Building Code (ICBO, 1994). Accordingly, the potential for relatively strong seismic accelerations will need to be considered in the design of proposed improvements. 7. LIMITATIONS The field evaluation and geotechnical analysis presented in this report have been conducted in ac- cordance with current engineering practice and the standard of care exercised by reputable geotechnical consultants performing similar tasks in this area. No other warranty, implied or ex- pressed, is made regarding the conclusions, recommendations, and professional opinions expressed in this report. Variations may exist and conditions not observed or described in this re- port may be encountered. Our preliminary conclusions and recommendations are based on an analysis of the observed conditions and the referenced background information. The purpose of this study was to evaluate geologic and geotechnical conditions within the project site and to provide a geotechnical reconnaissance report to assist in the preparation of environ- mental impact documents for the project. A comprehensive geotechnical evaluation, including subsurface exploration and laboratory testing, should be performed prior to design and construc- tion of structural improvements. 3635-01eir.doc RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 8. SELECTED REFERENCES Agra Earth and Environmental, Inc., 1997, El Camino Real Bridge, dated January 15. American Geotechnical, 1983, Preliminary Geotechnical Investigation, 400Acre Kelly Property, Carlsbad, California, dated July 29. Anderson, J.G., M. ERRI, Rockwell, T.K., and Agnew, D.C., 1989, Past and Possible Future Earthquakes of Significance to the San Diego Region: Earthquake Spectra, Volume 5, No. 2. California Division of Mines and Geology (CDMG), 1991, State of California, Special Studies Zones, Point Loma Quadrangle: effective November 1, 1991, scale 1:24,000. City of Carlsbad, 1988, Orthophoto Map, Sheet 64 of 225, Scale 1" = 100', dated October. County of San Diego, 1974, Topographic Survey, Sheet 358-1677, Scale 1" = 200', dated De- cember 11. International Conference of Building Officials (ICBO), 1994, Uniform Building Code, Structural Engineering Design Provisions: Volume 2. Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, California Geologic Data Map No. 6, scale 1:750,000. Mualchin, L., and Jones, A.L., 1992, Peak Acceleration from Maximum Credible Earthquakes in California (Rock and Stiff-Soil Sites): California Division of Mines and Geology, DMG Open-File Report 92-1. Mualchin, L., 1996, A Technical Report to Accompany the Caltrans California Seismic Hazard Map, 1996, (Based on Maximum Credible Earthquakes), California Department of Trans- portation, Engineering Service Center, Office of Earthquake Engineering. Norris, R.M., and Webb, R.W., 1990, Geology of California: John Wiley & Sons, Inc. Owen Geotechnical, 1985, Supplemental Geotechnical Investigation and Grading Plan Review, Phase I Grading, Kelly Ranch, Carlsbad, California, dated July 19. Ploessel, M.R., and Slosson, J.E., 1974, Repeatable High Ground Accelerations from Earth- quakes; Important Design Criteria: California Geology, September 1974. Rockwell, T.K., Lindvall, S.C. Haraden, C.C., Hirabayashi, C.K., and Baker, E., 1991, Minimum Holocene Slip Rate for the Rose Canyon Fault in San Diego, California in Abbott, P.L. and Elliott, W.J,, eds. Environment Perils, San Diego Region: San Diego Association of Geologists. Tan, S.S. and Kennedy, M.P., 1996, Geologic Maps of the Northwestern Part of San Diego County, California,, California Division of Mines and Geology, Open-File Report 96-02. 3635-0 leii.doc 10 RECON June 4, 1998 El Camino Real Widening Project Project No. 103635-01 Treiman, J.A., 1984, The Rose Canyon Fault Zone: California Division of Mines and Geology. Treiman, J.A., 1993, Rose Canyon Fault Zone, Southern California: California Division of Mines and Geology. United States Geological Survey (USGS), 1968 (Photorevised 1975), San Luis Rey Quadrangle, 7.5 Minute Series Topographic Map, San Diego County, California; scale 1:24,000. United States Department of Agriculture (USDA), 1973, Soil Survey, San Diego Area, California. Weber, F.H., 1963, Geology and Mineral Resources of San Diego County, California: California Division of Mines and Geology, County Report No. 3. Weber, F.H., 1982, Recent Slope Failures, Ancient landslides, and Related Geology of the North- Central Coastal Area, San Diego County, California, California Division of Mines and Ge- ology, Open-File Report 82-12 LA, dated July 1. Wesnousky, S.G., 1986, Earthquakes, Faults, and Seismic Hazards in California: Journal of Geo- physical Research, Vol. 91, No. B12. Woodward-Clyde Consultants, 1996, Geotechnical Investigation, Cannon Road-Reach 2, Carlsbad, California, dated August 26. Woodward-Clyde Consultants, 1997, Geotechnical Evaluation, Agua Hedionda Bridge Embank- ment, Cannon Road West, Carlsbad, California, dated July 16. AERIAL PHOTOGRAPHS Source Date Flight Numbers Scale USDA 4-11-53 AXN-8M 69 and 70 1:20,000 363S-01eir.doc 11 RECON El Camino Real Widening Project June 4, 1998 Project No. 103635-01 Table 1-Seismic Parameters for Maximum Credible Earthquakes Fault Agua Blanca-Coronado Bank Newport-Inglewood Offshore Zone of Deformation Rose Canyon San Clemente San Diego Trough San Jacinto Whittier-Elsinore Palos Verde Notes: Fault-to-Site Distance (miles) 22 30 7 4 56 31 45 21 53 Maximum Probable Earthquake Magnitudes1 7.7 7.0 7.0 7.0 7.3 7.7 7.5 7.5 7.0 Estimated Acceleration (g) Peak Horizontal Bedrock2 0.23 0.09 0.34 0.45 0.05 0.14 0.08 0.20 0.04 Repeatable High Ground3 0.23 0.09 0.22 0.29 0.05 0.14 0.08 0.20 0.04 'After Anderson etal., 1989, and Mualchin, 1996 2Mualchin and Jones, 1992 3Ploessel and Slosson, 1974 3635-01rir.doc 12 ^^iiss-Tjiw,/^^ v.«"S"j! ay^*-' t3t, / CARLSBAD< / ii REFERENCE: 1997 Thomas Guide for San Diego County, Street Guide and Directory 0 2400 4800 Approximate Scale in Feet NORTH r SITE LOCATION MAP ^ EL CAMINO REAL ROAD WIDENING STATION 441+00 453+00 c CARLSBAD, CALIFORNIA j r PROJECT NO. ^ 103635-01 DATE A r FIGURE ^\ 6/98 JV. 1 J V 3 /£rV/sSVrJ V -;'r7 c *K X / 'i- /.-v^ * .-f I Tft:^^^* : '•- •/ L^ | v V"' .<>'' SN. ./^ravel 2000 2000 4000 Approximate Scale in Feet REFERENCE: U.S.G.S.. SAN LUIS REY QUADRANGLE, 7.5 MINUTE SERIES (TOPOGRAPHIC) MAR DATED 1955. REVISED 1971. N A — TOPOGRAPHIC MAP EL CAMINO REAL ROAD WIDENING STATION 441+00 TO 453+00 CARLSBAD, CALIFORNIA f PROJECTNO. ^ 103635-01 DATE 6/98 K FIGURE " 2 . Xj.^4 I \ \CT /»CTJ- FAULT LOCATION MAP EL CAMINO REAL ROAD WIDENING STATION 441+00 TO 453+00 CARLSBAD, CALIFORNIA f PROJECT NO. \^ 103635-01 DATE A 6/98 ) FK3URE 3