PALEONTOLOGICAL IDENTIFICATION REPORT SABRE SPRINGS/PEÑASQUITOS TRANSIT CENTER PROJECT

Transcription

1 PALEONTOLOGICAL IDENTIFICATION REPORT SABRE SPRINGS/PEÑASQUITOS TRANSIT CENTER PROJECT Prepared for: California Department of Transportation District Taylor Street San Diego, California Prepared by: Department of PaleoServices San Diego Natural History Museum P.O. Box San Diego, California Thomas A. Deméré, Ph.D., Director Sarah A. Siren, M.S., Paleontological Field Manager 12 May 2010 For individuals with sensory disabilities, this document is available in alternate formats. Please call or write to call or write to Department of Transportation, Attn: David Nagy, Environmental Branch B Chief, MS 242, 4050 Taylor Street, San Diego, CA 92110; (619) or call the California Relay Service TTY number 1 (800)

2 TABLE OF CONTENTS INTRODUCTION... 1 PROJECT ALTERNATIVES... 2 PROJECT NEED AND OBJECTIVE... 2 SDNHM SCOPE OF WORK... 2 METHODOLOGY... 5 EXISTING CONDITIONS... 5 Physical Geologic Setting... 5 Santiago Peak Volcanics... 6 Description... 6 Paleontology... 6 Distribution... 6 Unnamed Alluvium and Slopewash Deposits... 8 Description... 8 Paleontology... 8 Distribution... 8 PALEONTOLOGICAL RESOURCE ASSESSMENT... 8 Sensitivity... 8 Maximum Sensitivity... 9 Major Sensitivity... 9 Minor Sensitivity... 9 Zero Sensitivity IMPACT ANALYSIS Introduction High significance Moderate significance Low significance Zero significance Site-Specific Impacts Recommended Course of Action REFERENCES CITED APPENDIX: Personnel Qualifications i

3 INTRODUCTION The California Department of Transportation (Caltrans), in cooperation with the Federal Highway Administration (FHWA), and the San Diego Association of Governments (SANDAG), proposes modifications to improve the existing Sabre Springs/Peñasquitos Transit Station. Proposed improvements include construction of a parking structure and park-and-ride facility. The project site is located at Sabre Springs Parkway, within the Sabre Springs Community Plan Area of the City of San Diego, San Diego County, California (Figure 1). The project site is bounded to the north by State Route (SR)-56 / Ted Williams Parkway, to the east by Sabre Springs Parkway, and to the south by Evening Creek Drive North. Project Description The proposed project consists of the construction of a four-level parking structure and associated improvements within the existing Sabre Springs/Peñasquitos Transit Center. The Sabre Springs/Peñasquitos Transit Center is presently characterized by an approximately 4-acre paved park-and-ride facility that accommodates 150 surface parking spaces; transit amenities including bus shelters, benches, and bike storage; and temporary buildings associated with the Interstate (I)-15 Corridor Express Lanes (Managed Lanes) Project. The four-level parking structure would be located in the southern portion of the transit center, adjacent to Carmel Mountain Express Drive and Sabre Springs Parkway, and would accommodate approximately 641 parking spaces. Approximately 86 parking spaces would be located immediately north of the parking structure in a reconfigured surface parking lot. A new Bus Rapid Transit (BRT) loop with eight bus bays and transit-related furnishings such as bus shelters and benches would be located in the northern portion of the site adjacent to Ted Williams Parkway. Circulation within the transit center would be revised to accommodate the new parking structure. An unnamed paved driveway that currently bisects the transit center would be removed. A second paved driveway that runs adjacent to Chicarita Creek along the western perimeter of the project site would be widened to meet City of San Diego roadway design standards. Landscaping would be installed throughout the newly configured transit center. Security lighting would be installed within the parking structure and replaced where appropriate to provide adequate lighting during early morning and night-time hours. The transit center would continue to operate between the hours of 5am and 9pm. Project construction is expected to commence in summer 2011 and would continue for approximately 12 months. Staging of construction equipment and materials storage for the proposed parking structure would be located within the transit center and/or at an existing nearby staging location just south of Ted Williams Parkway, west of I-15. Construction would be phased to allow the transit center to remain in service during construction of the project. 1

4 PROJECT ALTERNATIVES For the project, two alternatives are being studied: No Build Under the No Build Alternative no improvements will be made to the existing transit center. Transit Station Alternative - Originating at the present I-15 intersection with SR-56 / Ted Williams Parkway, this alternative includes construction of a parking structure and park-and-ride facility at the project site. The Transit Station Alternative proposes to add a parking structure immediately west of the Sabre Springs Parkway offramp from SR-56 / Ted Williams Parkway, north of Evening Creek Drive. Surface parking, including a north and south lot, for a park-and-ride facility is also proposed, in addition to a bus loop adjacent to the intersection between Sabre Springs Parkway and the Ted Williams Parkway ramp (Figure 2). PROJECT NEED AND OBJECTIVE There is a need for additional vehicle parking spaces at the Sabre Springs/ Peñasquitos Transit Center to meet future demand associated with a high-frequency express bus system - Bus Rapid Transit - along the I-15 corridor. The proposed project seeks to satisfy the need for additional parking at the transit center and support the overall vision of the I-15 Managed Lanes Project. SDNHM SCOPE OF WORK For the project, the San Diego Natural History Museum (SDNHM) is tasked by Caltrans to complete a paleontological assessment of the project and provide a Paleontological Identification Report (PIR). The PIR is to provide an assessment of the paleontological resource potential within the project site. Specifically, the PIR is intended to summarize the proposed project and the assumed project footprint, identify the data sources consulted, identify the specific geologic formations and fossils that may be encountered, assess potential impacts to paleontologically sensitive geologic formations, and provide a recommended course of action related to paleontological resources. This report was prepared by Thomas A. Deméré, Ph.D. and Sarah A. Siren, M.S., of the Department of PaleoServices at SDNHM, San Diego, California (Appendix). Additional discussion of report methodology is provided below. 2

5 Figure 1. Map of western San Diego County, California with the approximate location of the Sabre Springs/Peñasquitos Transit Center project area. 3

6 Figure 2. Preliminary construction drawing for proposed improvements to the Sabre Springs/Peñasquitos Transit Center project in the City of San Diego, California (courtesy of David Evans and Associates, Inc., 2010). 4

7 As defined here, paleontological resources (i.e., fossils) are the remains and/or traces of prehistoric plant and animal life exclusive of humans. Fossil remains such as bones, teeth, shells, leaves, and wood are found in the geologic deposits (formations) within which they were originally buried. For the purposes of this report, paleontological resources can be thought of as including not only the actual fossil remains but also the collecting localities and the geologic formations containing those localities. METHODOLOGY A review was conducted of relevant published and unpublished geologic reports (Kennedy and Peterson, 1975; Kleinfelder West, Inc., 2009), and paleontological site records housed at the Department of Paleontology at SDNHM and the online database of the department of Invertebrate Paleontology, Natural History Museum of Los Angeles County (LACM). This approach was followed in recognition of the direct relationship between paleontological resources and the geologic deposits/formations within which they occur. Knowing the geology of a particular area and the past fossil productivity of those deposits/formations it is possible to make reasonable predictions about where fossils will, or will not, be encountered. EXISTING CONDITIONS Physical Geologic Setting The Sabre Springs/Peñasquitos Transit Station project site lies within the western foothills of the Peninsular Ranges of Mesozoic age (~125 to 90 million years old [Ma]), which are overlain to the west by younger sedimentary deposits of Cenozoic age (~45 Ma to 11,000 years old; Walawender, 2000). The area is characterized by Mesozoic igneous and metamorphic bedrock with sedimentary deposits blanketing the lower lying topography (Kennedy and Peterson, 1975). According to published geologic maps and unpublished geotechnical reports (Kennedy and Peterson, 1975; Kleinfelder West, Inc., 2009), the surficial geologic deposits at the project site consist of Holocene alluvium and slope wash deposits (Qal+Qsw; <5,000 years old). However, adjacent to the project site are rocks mapped as the Santiago Peak Volcanics of late Jurassic to early Cretaceous age (~140 to 120 Ma, Figure 3). These older metavolcanic rocks were found to underlie the project site at depths of one to five feet below existing ground surface. Other geologic rock units exposed nearby include Cretaceous (~120 Ma) granitic bedrock and Eocene (~45 to 42 Ma) sedimentary rock units (Mission Valley Formation, Stadium Conglomerate, and Friars Formation; Figure 3). According to the preliminary geotechnical foundation report for the transit station (Kleinfelder West, Inc., 2009), artificial fill materials underlie the entire project site and vary in thickness from one to 15 feet. In places the artificial fill materials overlie 5

8 Quaternary alluvium, while elsewhere the fill materials directly overlie metavolcanic rocks of the Santiago Peak Volcanics. Santiago Peak Volcanics Description Immediately surrounding the project site, metavolcanic rocks mapped by Kennedy and Peterson (1975) as the Santiago Peak Volcanics (Jsp) are the dominant exposed bedrock unit. The Santiago Peak Volcanics are mainly composed of volcanic breccias, with lesser amounts of volcanic tuffs and flows. In some areas, slightly-to-moderately metamorphosed marine mudstones and sandstones appear to be interbedded with the volcanic rocks (Fife et al., 1967). Radiometric dates on the volcanic flow-rocks of the Santiago Peak Volcanics have yielded earliest Cretaceous ages, approximately 130 to 120 Ma (Herzig and Kimbrough, 1991). The Santiago Peak Volcanics were altered during emplacement of the vast volumes of magma generated by early Cretaceous subduction of a large lithospheric plate (Walwender, 2000). These magmas subsequently cooled to form the plutonic ( granitic ) rocks of the Peninsular Ranges Batholith. Paleontology In general, the molten origin of the Santiago Peak Volcanics precludes the possible discovery of fossil remains. However, some of the volcanic breccias contain petrified wood, as in Mira Mesa and near Rancho Santa Fe (D'Vincent, 1967). In addition, certain exposures of the metasedimentary portion of this formation have produced important remains of siliceous microfossils (e.g., radiolarians: Jones and Miller 1982) and marine macroinvertebrates including belemnites and clams (Jones and Miller, 1982). There are currently no records of any paleontological collecting sites in these rocks as exposed in the vicinity of the project site. Because the Santiago Peak Volcanics within the project site have been characterized as weathered metavolcanic rock (Kleinfelder West, Inc., 2009), they are here considered to not contain any paleontological resources. Distribution East and west of the proposed project site are rocks mapped as the Santiago Peak Volcanics (Kennedy and Peterson, 1975; Figure 3). In addition, preliminary geotechnical results indicate that this rock unit is present at depth within the project site (Kleinfelder West, Inc., 2009). 6

9 Project Location Figure 3. Geological map of the area around the Sabre Springs/Peñasquitos Transit Center project site (black polygon). Geology based on mapping by Kennedy and Peterson (1975). Holocene alluvium and slope wash deposits (yellow, Qal+Qsw) are mapped within the project boundaries. Adjacent to the project site are metavolcanic rocks mapped as the Jurassic Santiago Peak Volcanics (green, Jsp). Other nearby geological rock units include Cretaceous granitic bedrock (pink stippled, Kg) and Eocene sedimentary rock units (Tmv, Mission Valley Formation [purple]; Tst, Stadium Conglomerate [orange]; and Tf, Friars Formation [blue-green]). 7

10 Unnamed Alluvium and Slopewash Deposits Description Surface deposits within the project site are mapped as Holocene-age (Qal+Qsw; < 5,000 years ago) alluvium and slopewash (Kennedy and Peterson, 1975). These deposits are locally derived from ephemeral stream drainages, such as those associated with the creek west and adjacent to the project site. However, the preliminary geotechnical foundation report for the project site states that alluvial deposits were encountered in only one borehole and at a depth of 16 feet below ground surface (Kleinfelder West, Inc., 2009). Paleontology The Holocene age of these deposits indicates they are too young to contain true fossil remains or traces. Consequently, they do not represent significant paleontological resources. Distribution Unnamed Holocene alluvium and slopewash deposits are mapped beneath the entire footprint of the proposed project site, where they directly overlie older metavolcanic bedrock mapped as the Santiago Peak Volcanics (Figure 3). More detailed geotechnical information reveals that these deposits are in fact adjacent to the site, and will likely not be encountered during construction (Kleinfelder West, Inc., 2009). PALEONTOLOGICAL RESOURCE ASSESSMENT According to paleontological site records housed at SDNHM and LACM, no previously recorded fossil collecting localities occur within the immediate vicinity of the project site. Although previously recorded SDNHM fossil collecting localities do occur less than a mile west (Rancho Penasquitos) and a mile northeast (Carmel Mountain Ranch), these localities were discovered in Eocene-age deposits that do not occur within or nearby the project site (Kennedy and Peterson, 1975). Thus, paleontological resources are not anticipated to occur within the project site. Sensitivity Paleontology is a multidisciplinary science that combines elements of geology, biology, chemistry, and physics in an effort to understand the history of life on earth. Paleontological resources, or fossils, are the remains, imprints or traces of once-living organisms preserved in sedimentary rocks. Fossils include mineralized, partially mineralized, or unmineralized bones and teeth, soft tissues, shells, wood, leaf impressions, footprints, burrows, and microscopic remains. The fossil record is the only direct evidence that life on earth has existed for more than 3.6 billion years. Fossils are considered non-renewable resources because the organisms they represent no longer exist. Thus, once destroyed, a fossil can never be replaced. Fossils are important scientific and educational resources because they are used to: 8

11 Study the evolutionary relationships between extinct organisms, as well as their relationships to modern groups. Elucidate the taphonomic, behavioral, temporal, and diagenetic pathways responsible for fossil preservation, including the biases inherent in the fossil record. Reconstruct prehistoric environments, climate change, and paleoecological relationships. Provide a measure of relative geologic dating which forms the basis for biochronology and biostratigraphy, and which is an independent and corroborating line of evidence for isotopic dating. Study the geographic distribution of organisms and tectonic movements of land masses and ocean basins through time. Study patterns and processes of evolution, extinction and speciation. Identify past and potential future human-caused effects to global environments and climates. The following levels of paleontological resource sensitivity are rated for individual formations and recognize the important relationship between fossils and the geologic formations within which they are entombed. Maximum Sensitivity Maximum (or high) sensitivity is assigned to geologic rock units (formations) known to contain paleontological localities with rare, well-preserved, critical fossil materials for stratigraphic or paleoenvironmental interpretation, and fossils providing important information about the paleobiology and evolutionary history (phylogeny) of animal and plant groups. Generally speaking, highly sensitive formations produce vertebrate fossil remains or are considered to have the potential to produce such remains. Major Sensitivity Major (or moderate) sensitivity is assigned to geologic formations known to contain paleontological localities with poorly preserved, common elsewhere, or stratigraphically unimportant fossil material. The moderate sensitivity category is also applied to geologic formations that are judged to have a strong, but unproven potential for producing important fossil remains. Minor Sensitivity Minor (or low) sensitivity is assigned to geologic formations that, based on their relatively youthful age and/or high-energy depositional history, are judged unlikely to produce important fossil remains. Typically, minor sensitivity formations produce poorlypreserved invertebrate fossil remains in low abundance. Due to the young age and coarse- 9

12 coarse-grained nature of younger alluvium, these surficial sedimentary deposits are generally considered to have little potential to yield scientifically significant fossils. However, on occasion deeper excavations into sedimentary deposits mapped as younger alluvium penetrate into alluvial deposits of Pleistocene age and do yield fossils. For this reason, sedimentary deposits mapped as younger alluvium are generally assigned a low paleontological resource sensitivity (Deméré and Walsh, 1993). Zero Sensitivity Zero (or no) sensitivity is assigned to geologic formations that are entirely igneous in origin, and therefore have no potential for producing fossil remains. Moreover, any disturbed sediments at the surface or imported artificial fill would have this designation. Artificial fill materials and metavolcanic rocks confirmed by subsurface investigation by the geotechnical consultant within the project site have been assigned a zero paleontological resource sensitivity (Kleinfelder West, Inc., 2009). IMPACT ANALYSIS Introduction Direct impacts to paleontological resources occur when earthwork activities, such as mass grading and/or trenching operations, cut into the geological deposits (formations) within which fossils are buried. These direct impacts are in the form of physical destruction of fossil remains. Since fossils are the remains of prehistoric animal and plant life and they are considered to be nonrenewable, such impacts can be significant and, under the California Environmental Quality Act (CEQA) guidelines, require mitigation. Impacts to paleontological resources are rated in this report from high to zero depending upon the resource sensitivity of impacted formations. The specific criteria applied for each impact category are summarized below. High significance Impacts to geologic rock units/formations assigned maximum paleontological resource sensitivity - None in the project site. Moderate significance Impacts to geologic rock units/formations assigned major and/or unproven/undetermined paleontological resource sensitivity - None in the project site. Low significance Impacts to geologic rock units/formations assigned minor paleontological resource sensitivity None in the project. 10

13 Zero significance Impacts to geologic rock units/formations assigned zero paleontological resource sensitivity formations Santiago Peak Volcanics, artificial fill, or previously disturbed sediments at the surface of the project site (Kleinfelder West, Inc., 2009; Figure 3). Site-Specific Impacts Potential impacts to scientifically significant paleontological resources typically occur in the form of destruction of buried fossil remains during earthmoving activities associated with construction. No Build Alternative Because the No-Build Alternative will not involve any construction related excavations there will be no direct impacts to paleontological resources. Transit Station Alternative Construction related excavations for the proposed Transit Station Alternative will be minor and have no potential to directly impact paleontological resources. Although the young sedimentary deposits mapped by Kennedy and Peterson (1975) would generally have a low potential to yield fossil resources, the geotechnical consultant instead observed artificial fill materials overlying highly weathered metavolcanic bedrock during site investigations. These site conditions indicate that this alternative has no potential to impact paleontological resources. Recommended Course of Action Based on the fact that geologic rock units within the project site have no potential to yield paleontological resources, no further action is recommended at this time. 11

14 REFERENCES CITED Deméré, T.A., and S.L. Walsh, 1993, Paleontological Resources, County of San Diego: Prepared for the Department of Public Works, County of San Diego, p D Vincent, S., 1967, Primitive Sequoia not previously identified. California Garden, August-September 1967: Fife, D.L., J.A. Minch, and P.J. Crampton, 1967, Late Jurassic Age of the Santiago Peak Volcanics, California: Geol. Soc. America Bull., v.78, p Herzig, C.T., and D.J. Kimbrough, 1991, Early Cretaceous zircon ages prove a nonaccretionary origin for the Santiago Peak Volcanics, northern Santa Ana Mountains, California. Geological Society of America, Cordilleran Section, Abstracts with Programs 23:35. Jones, D.A., and R.H. Miller, 1982, Jurassic fossils from the Santiago Peak Volcanics, San Diego County, California. In, P.L. Abbott (ed.). Geologic Studies in San Diego. Field Trip Guidebook, San Diego Association of Geologists, San Diego Kennedy, M.P., and G.L. Peterson, 1975, Geology of the San Diego metropolitan area, California. Section B - Eastern San Diego metropolitan area. California Division of Mines and Geology, Bulletin 200: Kleinfelder West, Inc., 2009, Preliminary Foundation Report, Proposed Parking Garage, Sabre Springs/Peñasquitos Transit Station, Sabre Springs Parkway, San Diego County, California, prepared for David Evans and Associates, Inc. Walawender, M.J., 2000, The Peninsular Ranges: A Geological Guide to San Diego s Back Country. Kendall/Hunt Publishing Company, Dubuque, Iowa. 12

15 APPENDIX: PERSONNEL QUALIFICATIONS

16 Thomas A. Deméré, Director, PaleoServices Education: Ph.D. Biology (University of California, Los Angeles), M.S. Geology (University of Southern California), B.S. Geology (San Diego State University). Project Responsibilities: Project management. Title: Director of PaleoServices; Curator, Department of Paleontology Certification: Qualified Paleontologist, City of San Diego Dr. Deméré has worked as a professional paleontologist since 1974, first as a micropaleontologist in the petroleum industry and then as a paleontologist with the San Diego Natural History Museum involved with collecting, curating, and interpreting fossils. Since 1994, Tom has served as Curator of Paleontology and Director of PaleoServices at the Museum. Dr. Deméré is the author of numerous scientific and popular articles dealing with the paleontological history of southern California and the evolutionary history of marine mammals. Since 1981 he has also worked as an environmental consultant to various planning firms, municipalities, and land development companies. In this last capacity, Dr. Deméré s work has ranged from initial resource assessments, through impact evaluation, to actual impact mitigation. Although the majority of this work has been with residential and commercial developments within San Diego County, it has also involved a number of water, sewer, and natural gas pipeline and utility transmission line projects in southern California. Sarah A. Siren Paleontological Field Manager, PaleoServices Education: M.S. Paleontology (South Dakota School of Mines and Technology), B.S. Geology (The George Washington University), B.A. French Language & Literature (The George Washington University) Project Responsibilities: Recovery of stratigraphic and taphonomic data, collection of geographic and topographic information, final report preparation Title: Paleontological Field Manager Certification: Qualified Paleontologist, City of San Diego; Orange County Certified Paleontologist; Geologist-in-Training, California, No. 167; 40-hour HAZWOPER Training ssiren@sdnhm.org Ms. Siren received a Bachelor of Science Degree in Geology (1999) from The George Washington University and was awarded a Master's Degree in Paleontology (2002) from the South Dakota School of Mines and Technology. She is an associate geology professor at Saddleback Community College in Mission Viejo, California and a curatorial assistant with the Natural History Museum of Los Angeles County. Sarah has conducted studies at both the Smithsonian Institution and Badlands National Park, and has supervised as lead research scientist for various field activities, curation projects, and laboratory preparations. Her diverse experience includes monitoring, identifying, mapping, and preparing fossils. She has served as Project Manager and Paleontologist for numerous projects in southern California involving multiple agencies, public and private sector clients, a variety of resources, and multidisciplinary staff supervision. Sarah is a Geologist-in-Training (no.167) with the State of California, an Orange County Certified Paleontologist, and a Qualified Paleontologist with the City of San Diego.