HomeMy WebLinkAboutAttachment 8K - Paleontological Resources Technical Report
Paleontological Resources Technical Report
Nirvana Industrial Buildings and Self Storage Complex
City of Chula Vista
San Diego County, California
March 23, 2022 (revised February 6, 2023)
Prepared for:
VWP-OP Nirvana Owner, LLC
2390 E. Camelback Rd. Ste. 305
Phoenix, AZ 85016
Prepared by:
Department of PaleoServices
San Diego Natural History Museum
P.O. Box 121390
San Diego, California 92112-1390
Katie M. McComas, M.S., Paleontological Report Writer & GIS Specialist
Thomas A. Deméré, Ph.D., Principal Paleontologist
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report i
Executive Summary
This paleontological resources technical report was prepared for the Nirvana Industrial Buildings and
Self Storage Complex project (Project) located in the southern portion of the City of Chula Vista, San
Diego County, California. The purpose of this report is to identify and summarize paleontological
resources that occur in the vicinity of the Project site, identify Project elements (if any) that may
negatively impact paleontological resources, and if necessary provide recommendations to reduce any
potential negative impacts to less than significant levels. The report includes the results of a literature
review and an institutional paleontological records search conducted at the San Diego Natural History
Museum (SDNHM).
The approximately 13.3-acre Project site is located at 821 Main Street, and is bordered to the south by
Main Street, to the north and west by existing commercial development, and to the east by a small
parcel of the Otay Ranch Village 3 development that lies at the northwest corner of Main Street and
Heritage Road. The Project proposes to construct three industrial buildings and a self storage building.
Additional planned site improvements include the installation of subgrade utilities (sewer and water)
and stormwater management systems, surface parking and internal driveways, and landscaping. The
Project also includes off-site grading of 0.37 acres to the north of the site (for the Project driveway and
additional areas), 0.21 acres to the east of the site (to stabilize an existing slope), 0.22 acres of City right-
of-way along the Main Street frontage, and 0.18 acres west of the site (to eliminate low and high points
along the proposed retaining wall and promote positive drainage in a concrete brow ditch). The total
proposed graded area is 14.44 acres.
Published geologic mapping reports that the Project site is underlain by the middle Eocene-age
(approximately 43 million years old) Mission Valley Formation, remnant terraces of overlying middle to
late Pleistocene-age (approximately 774,000 to 11,700 years old) old alluvial flood plain deposits, and
Holocene-age (generally less than 11,700 years old) young colluvial deposits that have accumulated
along a central drainage that divides the site approximately in half. In contrast, the site-specific
geotechnical evaluation report assigns the sedimentary bedrock underlying the Project site to the late
Oligocene-age (approximately 29 million years old) Otay Formation, not the Mission Valley Formation. In
addition, the geotechnical evaluation reports that the Otay Formation is exposed in the lower portion of
the slope along the north side of Main Street, and is capped elsewhere within the site by Pleistocene-
age terrace deposits (or old alluvial flood plain deposits) measuring between 4 and 30 feet thick.
Holocene-age alluvium measuring at least 5 feet thick is also reported to be present in shallow, north-
south trending drainages that cross the western and central portions of the site. Superficial Holocene-
age topsoil and slope wash are reported to each measure between 1 and 4 feet thick, with slope wash
restricted to the steep, south-facing slopes within the site and topsoil locally present across the site.
Finally, a wedge of undocumented fill is located within the north-central portion of the site at the top of
the central drainage, and is estimated to measure 10 to 20 feet thick.
Fossil collection localities have been documented within a one-mile radius of the Project site by SDNHM
staff from several of these geologic units: two localities within the Mission Valley Formation, which
produced fossil molds of marine mollusks and remains of marine vertebrates, such as sharks and rays;
seven localities within the Otay Formation, which produced fossil remains of artiodactyls, rodents, an
unidentified carnivore, and a squamate reptile; and one locality within Pleistocene-age old alluvial flood
plain deposits, which produced weathered upper molars and a right scapula of an ancient horse. Fluvial
deposits of the Mission Valley Formation have produced a diverse assemblage of terrestrial mammals as
well as fossilized wood, while the marine deposits have yielded a diverse fossil assemblage consisting of
marine organisms. The Otay Formation preserves a remarkably rich assemblage of terrestrial plants and
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report ii
animals consisting mostly of extinct land mammals, but also includes tortoise, lizards, and birds.
Pleistocene-age old alluvial flood plain deposits have produced fossils at numerous locations in coastal
San Diego County, and have yielded impressive collections of terrestrial vertebrates including pond
turtle, passenger pigeon, hawk, mole, rabbit, gopher, squirrel, capybara, wolf, horse, camel, deer, bison,
mastodon, mammoth, and ground sloth. Fossil collection localities are generally undocumented within
Holocene-age alluvium, slope wash, and topsoil and undocumented fill. Accordingly, the Mission Valley
Formation and Otay Formation are assigned a high paleontological sensitivity, Pleistocene-age old
alluvial flood plain deposits are assigned a moderate paleontological sensitivity, Holocene-age alluvium,
slope wash, and topsoil are assigned a low paleontological sensitivity, and undocumented fill deposits
are assigned zero paleontological sensitivity.
It is anticipated that all undocumented fill, all Holocene-age alluvium, slope wash, and topsoil, and the
vast majority of the Pleistocene-age old alluvial flood plain deposits present within the Project site will
be removed during grading. In addition, the underlying geologic unit (Mission Valley Formation or Otay
Formation) will be impacted near the base of excavations and during remedial grading to remove the
bentonitic claystone horizons. Thus, implementation of a paleontological mitigation program centered
around paleontological monitoring is recommended, as outlined in the provided Mitigation Measures 1–
7. Implementation of the paleontological mitigation program will reduce any Project-related impacts to
paleontological resources to less than significant levels.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report iii
Contents
Executive Summary .............................................................................................................................. i
1.0 Introduction ................................................................................................................................... 1
1.1 Project Description ....................................................................................................................... 1
1.2 Scope of Work .............................................................................................................................. 1
1.3 Definition of Paleontological Resources ....................................................................................... 1
1.3.1 Definition of Scientifically Significant Fossils ........................................................................ 3
1.4 Regulatory Framework ................................................................................................................. 3
1.4.1 State ...................................................................................................................................... 3
1.4.2 Local: City of Chula Vista ....................................................................................................... 4
2.0 Methods ........................................................................................................................................ 4
2.1 Paleontological Literature Review and Records Search ............................................................... 4
2.2 Paleontological Resource Assessment Criteria ............................................................................. 4
2.2.1 High Sensitivity ...................................................................................................................... 4
2.2.2 Moderate Sensitivity ............................................................................................................. 5
2.2.3 Low Sensitivity ....................................................................................................................... 5
2.2.4 Marginal Sensitivity ............................................................................................................... 5
2.2.5 Zero Sensitivity ...................................................................................................................... 5
2.3 Paleontological Impact Analysis ................................................................................................... 5
3.0 Results ........................................................................................................................................... 5
3.1 Results of the Literature Review and Records Search .................................................................. 5
3.1.1 Project Geology ..................................................................................................................... 6
3.1.2 Project Paleontology ............................................................................................................. 8
3.2 Results of the Paleontological Resource Assessment .................................................................. 9
3.3 Results of the Paleontological Impact Analysis .......................................................................... 11
4.0 Recommendations & Conclusions ................................................................................................. 11
4.1 Mitigation Measures ................................................................................................................... 12
5.0 References ................................................................................................................................... 13
Appendix A ........................................................................................................................................ A1
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 1
1.0 Introduction
1.1 Project Description
This technical report provides an assessment of paleontological resources for the Nirvana Industrial
Buildings and Self Storage Complex project (Project) site located in the southern portion of the City of
Chula Vista, San Diego County, California (Figure 1; City of Chula Vista, 2019; Esri, 2021).
The approximately 13.3-acre Project site is located at 821 Main Street, and is bordered to the south by
Main Street, to the north and west by existing commercial development, and to the east by a small
parcel of the Otay Ranch Village 3 development that lies at the northwest corner of Main Street and
Heritage Road. The Project proposes to construct three industrial buildings and a self storage building.
Additional planned site improvements include the installation of subgrade utilities (sewer and water)
and stormwater management systems, surface parking and internal driveways, and landscaping. The
Project also includes off-site grading of 0.37 acres to the north of the site (for the Project driveway and
additional areas), 0.21 acres to the east of the site (to stabilize an existing slope), 0.22 acres of City right-
of-way along the Main Street frontage, and 0.18 acres west of the site (to eliminate low and high points
along the proposed retaining wall and promote positive drainage in a concrete brow ditch). The total
proposed graded area is 14.44 acres.
1.2 Scope of Work
This paleontological resources technical report is being completed due to a review of maps that indicate
the Project site is partially underlain by sedimentary deposits assigned a moderate to high
paleontological sensitivity (Deméré and Walsh, 1993; Stephenson et al., 2009). The report is intended to
summarize existing paleontological resource data at the Project site, discuss the significance of these
resources, determine whether construction of the Project will impact paleontological resources, and
develop measures to mitigate any potential impacts to paleontological resources.
The report includes the results of a literature review and a search of the paleontological collections
records at the San Diego Natural History Museum (SDNHM). This report was written by Katie M.
McComas and Thomas A. Deméré of the Department of PaleoServices, SDNHM.
1.3 Definition of Paleontological Resources
As defined here, paleontological resources (i.e., fossils) are the buried remains and/or traces of
prehistoric organisms (i.e., animals, plants, and microbes). Body fossils such as bones, teeth, shells,
leaves, and wood, as well as trace fossils such as tracks, trails, burrows, and footprints, are found in the
geologic units/formations within which they were originally buried. The primary factor determining
whether an object is a fossil or not is not how the organic remain or trace is preserved (e.g., “petrified”),
but rather the age of the organic remain or trace. Although typically it is assumed that fossils must be
older than ~11,700 years (i.e., the generally accepted end of the last glacial period of the Pleistocene
Epoch), organic remains older than recorded human history and/or older than middle Holocene (about
5,000 radiocarbon years) can also be considered to represent fossils (SVP, 2010).
Fossils are considered important scientific and educational resources because they serve as direct and
indirect evidence of prehistoric life and are used to understand the history of life on Earth, the nature of
past environments and climates, the membership and structure of ancient ecosystems, and the pattern
and process of organic evolution and extinction. In addition, fossils are considered to be non-renewable
resources because typically the organisms they represent no longer exist. Thus, once destroyed, a
particular fossil can never be replaced.
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Finally, paleontological resources can be thought of as including not only the actual fossil remains and
traces, but also the fossil collecting localities and the geologic units containing those localities. The
locality includes both the geographic and stratigraphic context of fossils—the place on the earth and
stratum (deposited during a particular time in earth’s history) from which the fossils were collected.
Localities themselves may persist for decades, in the case of a fossil-bearing outcrop that is protected
from natural or human impacts, or may be temporarily exposed and ultimately destroyed, as in the case
of fossil-bearing strata uncovered by erosion or construction. Localities are documented with a set of
coordinates and a measured stratigraphic section tied to elevation detailing the lithology of the fossil-
bearing stratum as well as overlying and underlying strata. This information provides essential context
for any future scientific study of the recovered fossils.
1.3.1 Definition of Scientifically Significant Fossils
The California Environmental Quality Act (CEQA, Public Resources Code Section 21000 et seq.) dictates
that a paleontological resource is considered significant if it “has yielded, or may be likely to yield,
information important in prehistory or history” (Section 15064.5, [a][3][D]). The Society of Vertebrate
Paleontology (SVP) has further defined significant paleontological resources as consisting of “fossils and
fossiliferous deposits … consisting of identifiable vertebrate fossils, large or small, uncommon
invertebrate, plant, and trace fossils, and other data that provide taphonomic, taxonomic, phylogenetic,
paleoecologic, stratigraphic, and/or biochronologic information” (SVP, 2010).
1.4 Regulatory Framework
Paleontological resources are considered scientifically and educationally significant nonrenewable
resources; they are protected under a variety of laws, regulations, and ordinances. The Project site is
located within the City of Chula Vista in San Diego County, California. As such, state and local regulations
are applicable to the Project.
1.4.1 State
The California Environmental Quality Act (CEQA, Public Resources Code Section 21000 et seq.) protects
paleontological resources on both state and private lands in California. This act requires the
identification of environmental impacts of a proposed project, the determination of significance of the
impacts, and the identification of alternative and/or mitigation measures to reduce adverse
environmental impacts. The Guidelines for the Implementation of CEQA (Title 14, Chapter 3, California
Code of Regulations: 15000 et seq.) outlines these necessary procedures for complying with CEQA.
Paleontological resources are specifically included as a question in the CEQA Environmental Checklist
(Appendix G): “Will the proposed project directly or indirectly destroy a unique paleontological resource
or site or unique geologic feature.” Also applicable to paleontological resources is the checklist question:
“Does the project have the potential to… eliminate important examples of major periods of California
history or pre-history.” If significant paleontological resources may be impacted within a given project
site, CEQA provides that “a lead agency shall identify potentially feasible measures to mitigate
significant adverse changes in the significance of an historical resource. The lead agency shall ensure
that any adopted measures to mitigate or avoid significant adverse changes are fully enforceable
through permit conditions, agreements, or other measures” (Section 15064.5, [b][4]).
Other state requirements for paleontological resource management are included in the Public
Resources Code, Section 5097.5. These statutes prohibit the removal of any paleontological site or
feature on public lands without permission of the jurisdictional agency, defines the removal of
paleontological sites or features as a misdemeanor, and requires reasonable mitigation of adverse
impacts to paleontological resources from developments on public (state) lands.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 4
1.4.2 Local: City of Chula Vista
The City of Chula Vista General Plan (adopted 2005) addresses potential impacts to paleontological
resources within the Environmental Element of the General Plan (Chapter 9, Section 3.1.10) through two
policies, with the stated objective to: “Protect important paleontological resources and support and
encourage public education and awareness of such resources” (Objective E 10). The two policies
outlined in support of this objective are:
• Policy E 10.1—Continue to assess and mitigate the potential impacts of private development
and public facilities and infrastructure to paleontological resources in accordance with the
California Environmental Quality Act.
• Policy E 10.2—Support and encourage public education and awareness of local paleontological
resources, including the establishment of museums and educational opportunities accessible to
the public.
2.0 Methods
2.1 Paleontological Literature Review and Records Search
A review was conducted of relevant published geologic maps (e.g., Kennedy and Tan, 1977, 2008),
published geological and paleontological reports (e.g., Deméré, 1988; Walsh, 1996), the Project site-
specific geotechnical evaluation report (Geocon, Inc., 2021), and other relevant literature (e.g., field trip
guidebooks, theses and dissertations, and unpublished paleontological mitigation reports). This
approach was followed in recognition of the direct relationship between paleontological resources and
the geologic formations within which they are entombed. Knowing the geologic history of a particular
area and the fossil productivity of geologic formations that occur in that area, it is possible to predict
where fossils are likely or unlikely to be encountered.
A paleontological records search was also conducted at the SDNHM in order to determine if any
documented fossil collection localities occur within the Project site or immediately surrounding area.
The records search involved examination of the SDNHM paleontological database for any records of
known fossil collection localities within a 1-mile radius of the proposed Project site. The results of the
records search are discussed in the report.
2.2 Paleontological Resource Assessment Criteria
Impacts to paleontological resources are typically assigned a paleontological sensitivity rating based on
the resource potential of an impacted geologic unit. The County of San Diego has developed its own
guidelines for assigning paleontological sensitivity (Stephenson et al., 2009), which includes a five-tiered
scale of High Sensitivity, Moderate Sensitivity, Low Sensitivity, Marginal Sensitivity, or Zero Sensitivity
ratings. An expanded description of each paleontological sensitivity rating, as outlined by the County
(Stephenson et al., 2009) is provided below.
2.2.1 High Sensitivity
Geologic units with high sensitivity have produced, or are likely to produce, significant vertebrate,
invertebrate, or paleobotanical remains. High sensitivity geologic units may contain fossil materials that
are rare, well-preserved, critical for stratigraphic or paleoenvironmental interpretation, and/or provide
important information about the paleobiology and evolutionary history (phylogeny) of animal and plant
groups.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 5
2.2.2 Moderate Sensitivity
Moderate sensitivity is assigned to geologic units known to contain paleontological localities with fossil
material that is poorly preserved, common elsewhere, or stratigraphically unimportant.
2.2.3 Low Sensitivity
Low sensitivity is assigned to geologic units that, based on their relatively young age and/or high-energy
depositional history, are judged unlikely to produce important fossil remains. Typically, low sensitivity
units produce fossil remains in low abundance, or only produce common/widespread invertebrate
fossils whose taphonomy, phylogeny, and ecology is already well understood.
2.2.4 Marginal Sensitivity
Marginal sensitivity is assigned to geologic units that are composed either of volcaniclastic (derived from
volcanic sources) or metasedimentary rocks, but that nevertheless have a limited probability for
producing fossils from certain formations at localized outcrops.
2.2.5 Zero Sensitivity
Geologic units with no sensitivity are either entirely igneous in origin and therefore do not contain fossil
remains, or are moderately to highly metamorphosed and thus any contained fossil remains have been
destroyed. Undocumented fill materials also have no sensitivity, because the stratigraphic and geologic
context of any contained organic remains (i.e., fossils) has been lost.
2.3 Paleontological Impact Analysis
Direct impacts to paleontological resources occur when earthwork activities (e.g., grading, augering,
trenching), cut into the geologic units within which fossils are buried, and physically destroy the fossil
remains. As such, only earthwork activities that will disturb potentially fossil-bearing geologic units (i.e.,
those rated with a high or moderate paleontological sensitivity) have the potential to significantly
impact paleontological resources. Under California Environmental Quality Act and County of San Diego
guidelines, paleontological mitigation typically is recommended to reduce any negative impacts to
paleontological resources to less than significant levels.
The purpose of the impact analysis is to determine whether proposed Project-related earthwork may
disturb potentially fossil-bearing geologic units, and where and to what depths this earthwork will occur.
The paleontological impact analysis involved analysis of available Project documents (e.g., project plans),
and comparison with geological and paleontological data gathered during the literature review and
records search.
3.0 Results
3.1 Results of the Literature Review and Records Search
The Project site is located along the coastal plain of San Diego County, within the Peninsular Ranges
Geomorphic Province of California. Along the coastal plain, basement rocks of the early Cretaceous-age
Santiago Peak Volcanics and the Cretaceous-age Peninsular Ranges Batholith are nonconformably
overlain by a “layer cake” sequence of sedimentary strata of late Cretaceous, Eocene, Oligocene,
Miocene, Pliocene, and/or Pleistocene age (Givens and Kennedy, 1979; Hanna, 1926; Kennedy, 1975;
Kennedy and Moore, 1971; Kennedy and Peterson, 1975; Peterson and Kennedy, 1974; Walsh and
Deméré, 1991). Kennedy and Moore (1971) divided the Eocene portion of this sequence into the early
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 6
middle Eocene La Jolla Group and late middle Eocene Poway Group (which includes the Mission Valley
Formation), which together include nine formations.
The Eocene strata accumulated in a large depositional basin, the Cenozoic San Diego Embayment. A
large river system occupied the eastern portion of the embayment, while in the west, the alluvial and
fluvial paleoenvironments of this river system mixed with nearshore marine paleoenvironments in a
river-dominated delta (Kennedy and Moore, 1971). Farther west, the submarine portions of the delta
transitioned into continental shelf and slope paleoenvironments (May, 1985; May and Warme, 1991).
Thus, the Eocene strata record a series of intertonguing marine and terrestrial paleoenvironments
deposited over a relatively short lateral distance (west to east) during a period of approximately 10
million years (50 to 40 million years ago) (Walsh et al., 1996). Strata of the Mission Valley Formation
accumulated in a portion of the Eocene river floodplain, as well as on the adjacent Eocene continental
shelf (Kennedy and Moore, 1971; Walsh, 1996).
Following a period of erosion or nondeposition that lasted approximately 11 million years, deposition
resumed within the broad flood plain of a large, slow-moving river system that occupied the
southwestern coastal plain of San Diego. Conglomeratic channel lag deposits, sandy braided stream
deposits, and fine-grained lake and pond sediments of the Otay Formation provide a record of this
ancient paleoenvironment (Walsh and Deméré, 1991).
Approximately 28 million years later, during the Pleistocene, the prehistoric Otay River and its
tributaries carved out the Otay River Valley in response to changes in global sea level (Deméré and
Walsh, 1993). During periods of low sea level, the river incised through the Oligocene Otay Formation
and the underlying Eocene rocks. As sea level rose, alluvium was deposited and filled the valley. Several
cycles of fluctuating sea level led to the conditions observed today at the Project site, with Pleistocene-
aged old alluvial flood plain or terrace deposits buttressed against the older strata.
3.1.1 Project Geology
Based on published geologic mapping by Kennedy and Tan (2008), the Project site is reported to be
underlain by strata of the middle Eocene-age (approximately 43 million years old) Mission Valley
Formation, as well as middle to late Pleistocene-age (approximately 774,000 to 11,700 years old) old
alluvial flood plain deposits (Cohen et al., 2021) (Figure 2). In addition, Holocene-age (generally less than
11,700 years old) young colluvial deposits have accumulated along a central drainage that divides the
Project site approximately in half. These existing conditions were confirmed by SDNHM field
paleontologists during a 2015 paleontological field survey that was conducted prior to proposed
widening of Main Street (PaleoServices, 2015). The survey focused on the area along the north side of
Main Street, and documented a terrestrial red mudstone facies of the Mission Valley Formation that
consisted of pale red to grayish orange, well indurated, massive mudstones with minor claystone.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 7
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 8
In contrast, the site-specific geotechnical evaluation report assigns the sedimentary bedrock underlying
the Project site to the late Oligocene-age (approximately 29 million years old) Otay Formation, not the
Mission Valley Formation (Geocon, Inc., 2021). The geotechnical report describes these deposits as
“dense, silty, fine- to coarse-grained sandstone, clayey and sandy siltstone, and silty claystone with
continuous and discontinuous interbeds of highly expansive bentonitic claystone.” The geotechnical
evaluation reports that the Otay Formation is exposed in the lower portion of the slope along the north
side of Main Street, and is capped elsewhere within the site by Pleistocene-age terrace deposits (or
alluvial flood plain deposits) measuring between 4 and 30 feet thick that consist of “dense to very dense,
reddish brown, silty to clayey sand with gravel and cobbles.” Holocene-age alluvium measuring at least 5
feet thick is also reported to be present in shallow, north-south trending drainages that cross the
western and central portions of the site, and generally consists of loose to medium dense silty to clayey
sand with gravel and cobbles. Superficial Holocene-age topsoil and slope wash are reported to each
measure between 1 and 4 feet thick, with slope wash restricted to the steep, south-facing slopes within
the site and topsoil locally present across the site. Finally, a wedge of undocumented fill is reported to
occur within the north-central portion of the site at the top of the central drainage, and is estimated to
measure 10 to 20 feet thick (Geocon, Inc., 2021).
For the purposes of this report, it is not of paleontological importance to definitively know whether the
older sedimentary rocks exposed on the Project site represent the Mission Valley Formation or the Otay
Formation, because both geologic units are assigned a high paleontological sensitivity (see Section 3.3),
and thus impacts to either geologic unit would require paleontological mitigation. Given this level of
uncertainty but equivalent paleontological sensitivity, the following section provides general overviews
of the geology and paleontology of both geologic units.
3.1.2 Project Paleontology
The SDNHM has documented a total of 10 fossil collection localities from the geologic units underlying
the Project site within a one-mile radius of the proposed Project site (Appendix A). Two localities are
from the Mission Valley Formation, seven localities are from the Otay Formation, and one locality is
from Pleistocene-age old alluvial flood plain deposits. These localities are discussed in greater detail
below.
Fluvial deposits of the Mission Valley Formation have yielded a diverse assemblage of terrestrial
mammals, including opossums, insectivores, bats, rodents, primates, artiodactyls, and perissodactyls
(Golz and Lillegraven, 1977; Walsh, 1996), as well as fossilized wood (SDNHM unpublished
paleontological collections data), while the marine deposits have yielded a diverse fossil assemblage
consisting of marine microfossils (e.g., foraminifers), invertebrates (e.g., clams, snails, crustaceans, sand
dollars, sea urchins), and vertebrates (e.g., sharks, rays, bony fishes) (Deméré and Walsh, 1993). There
are two SDNHM localities from the Mission Valley Formation that lie between 0.5 and 0.75 miles to the
west and southwest of the Project site, both documented during previous paleontological monitoring of
construction earthwork. SDSNH Locality 4752, located within the Dennery Ranch residential
development along the north side of Otay Mesa, produced numerous burrows, along with internal and
external molds of bivalves and gastropods. SDSNH Locality 5648, located along the south side of Main
Street between Auto Park Avenue and Maxwell Road, produced numerous isolated teeth of sharks
(Striatolamna, Heterodontus, and Squatina) and rays (rhinobatids and myliobatids), and internal and
external molds of marine mollusks, primarily continental shelf-inhabiting bivalves (Glycymeris,
Acanthocardia, Spisula, and Callista).
The Otay Formation preserves a remarkably rich assemblage of terrestrial plants and animals consisting
mostly of extinct land mammals, but also includes tortoise, lizards, and birds. The land mammals include
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 9
exotic species of hedgehog, rhinoceros, and camel, as well as gopher, squirrel, mouse, and several
carnivores, including a small fox-like canid, a medium-sized short-faced dog, and a false-saber-toothed
nimravid (Deméré, 1986, 1988; Hoffman and Prothero, 2004; Prothero and Lubar, 2016). The most
common fossils are remains of oreodonts, an extinct group of wholly North American hoofed mammals
(ungulates) distantly related to camels and pigs. Plant fossils known from the Otay Formation include
leaf impressions of aquatic species like cattails and reeds. There are seven SDNHM localities from the
Otay Formation in the vicinity of the Project site, all documented during previous paleontological
monitoring of construction earthwork. Two localities (SDSNH Localities 4264 and 5411) were recovered
from the middle “gritstone member” of the Otay Formation during construction of residential
developments along the north side of Otay Mesa between 0.75 and 1.0 miles southwest of the Project
site, and produced numerous skulls, skeletons, and isolated cranial, mandibular, dental, and postcranial
remains of the oreodont Sespia. The remaining five localities lie between 0.75 and 1.0 miles northeast of
the Project site, and were documented within the upper “sandstone-mudstone member” of the Otay
Formation during excavations for the Otay Landfill (SDSNH Localities 4857, 6050, and 6051) and mass
grading for the Otay Ranch Village 2 South residential development (SDSNH Localities 7594 and 7599).
These localities produced teeth, jaws, and postcranial bones of artiodactyls (including camel, the
oreodonts Mesoreodon and Sespia, and the mouse deer Hypertragulus), teeth and jaws of rodents
(Leidymys and Heliscomys), a partial humerus of an unidentified carnivore, and a vertebra of a squamate
reptile.
Pleistocene-age old alluvial flood plain deposits have produced fossils at numerous locations in coastal
San Diego County, and have yielded impressive collections of terrestrial vertebrates including pond
turtle, passenger pigeon, hawk, mole, rabbit, gopher, squirrel, capybara, wolf, horse, camel, deer, bison,
mastodon, mammoth, and ground sloth (Chandler, 1982; Deméré et al., 2013; Guthrie, 2012; Jefferson,
1991; Majors, 1993; SDNHM unpublished paleontological collections data). The SDNHM has one locality
from Pleistocene-age old alluvial flood plain deposits in the vicinity of the Project site, located
approximately 0.75 to the southeast in the Otay River Valley along the east side of Heritage Road.
SDSNH Locality 6699 was discovered during monitoring of remediation grading activities at the former
Otay Skeet and Trap Shooting Range, and produced weathered upper molars and a right scapula of an
ancient horse (Equus sp.).
Fossil collection localities are generally undocumented within Holocene-age alluvium, slope wash, and
topsoil and undocumented fill. In the case of Holocene-age deposits, this is due to their relatively young
geologic age and the recognition that organic remains preserved in such deposits are conspecific with
organisms living in the area today. Artificial fill has been previously disturbed and may have been
imported to its current location. Any fossils these deposits may contain have lost their original
stratigraphic and geographic context, and are thus not considered to be scientifically significant.
3.2 Results of the Paleontological Resource Assessment
Following San Diego County’s paleontological sensitivity guidelines, as outlined in Section 2.2, the
sedimentary deposits underlying the Project site are assigned paleontological sensitivity ratings ranging
from zero to high (Table 1, Figure 3). The Mission Valley Formation is assigned a high paleontological
sensitivity based on the recovery of diverse and scientifically significant fossil assemblages of terrestrial
vertebrates and marine organisms from these strata. Likewise, the Otay Formation is assigned a high
paleontological sensitivity based on the recovery of scientifically significant fossil assemblages of
terrestrial mammals from this geologic unit. Pleistocene-age old alluvial flood plain deposits are
assigned a moderate paleontological sensitivity based on the scattered occurrence of scientifically
significant vertebrate fossils in similar deposits in western San Diego County. Holocene-age alluvium,
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 10
slope wash, and topsoil are assigned a low paleontological sensitivity, and undocumented fill deposits
are assigned zero paleontological sensitivity.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 11
Table 1. Summary of geologic units underlying the Project site and paleontological monitoring recommendations.
Geologic Unit Age Paleontological Sensitivity Monitoring
Recommended?
Undocumented fill Recent Zero sensitivity No
Young alluvium, slope wash, topsoil Holocene Low sensitivity No
Old alluvial flood plain deposits middle to late
Pleistocene Moderate sensitivity Yes
Otay Formation late Oligocene High sensitivity Yes
Mission Valley Formation middle Eocene High sensitivity Yes
3.3 Results of the Paleontological Impact Analysis
Based on a review of the available Project design review grading plans (dated 22 September 2021) and
geotechnical design recommendations (Geocon, Inc., 2021), it appears that proposed earthwork will
primarily involve grading to create a level building pad, located between approximately 183 and 186 feet
above sea level (asl). The building pad is proposed to be constructed as a transition pad, with cuts
primarily required in the northern portion of the site, and fill required in the southern portion of the
site. The estimated maximum cut depth as outlined on the Project design review grading plans is 35
vertical feet, with planned fill depths of up to 52 vertical feet. The geotechnical report also recommends
remedial grading to remove the bentonitic claystone horizons present within the Otay Formation (or
Mission Valley Formation) at or near the proposed finished pad grade. Current plans suggest that this
remedial grading may extend excavation depths an additional 10 or more feet below the finished grade.
Trenching for subgrade utilities and storm drains is also anticipated to require deeper excavations.
It is anticipated that all undocumented fill, all Holocene-age alluvium, slope wash, and topsoil, and the
vast majority of the Pleistocene-age old alluvial flood plain deposits present within the Project site will
be removed during grading. In addition, the underlying older geologic unit (Otay Formation or Mission
Valley Formation) will be impacted near the base of excavations and during remedial grading to remove
the bentonitic claystone horizons and during trenching for deep utilities.
4.0 Recommendations & Conclusions
The Project site is underlain by geologic units ranging from zero sensitivity (undocumented fill deposits)
to low sensitivity (Holocene-age young alluvium, slope wash, and topsoil) to moderate sensitivity
(Pleistocene-age old alluvial flood plain deposits) to high sensitivity (the Otay Formation or Mission
Valley Formation). Only excavation activities within Pleistocene-age old alluvial flood plain deposits, the
Otay Formation, and/or Mission Valley Formation have the potential to result in impacts to
paleontological resources. It is anticipated that Pleistocene-age old alluvial flood plain deposits will be
impacted during grading across the majority of the Project site and off-site areas (see Figure 3), while
the underlying older geologic unit (Otay Formation or Mission Valley Formation) will be impacted near
the base of excavations, during remedial grading to remove the bentonitic claystone horizons, and
during trenching for deep utilities. Therefore, these excavation activities have the potential to result in
impacts to paleontological resources.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 12
Implementation of a paleontological mitigation program, in the form of paleontological monitoring, is
recommended for earthwork at the Project site that may directly impact previously undisturbed
deposits of the Mission Valley Formation, Otay Formation, and/or Pleistocene-age old alluvial flood plain
deposits. Implementation of the following mitigation measures will reduce any Project-related impacts
to paleontological resources to a level that is less than significant. The mitigation measures outlined
below are based on established industry best practices (Murphey et al., 2019).
4.1 Mitigation Measures
1. Pre-construction (personnel and repository): Prior to the commencement of construction, a
qualified Project Paleontologist shall be retained to oversee the mitigation program (a Project
Paleontologist is a person with a Ph.D. or M.S. Degree in paleontology or related field, and who
has a working knowledge of San Diego County paleontology and documented experience in
professional paleontological procedures and techniques). In addition, a regional fossil repository
shall be designated to receive any discovered fossils. Because the Project is located in San Diego
County, the recommended repository is the San Diego Natural History Museum.
2. Pre-construction (meeting): The Project Paleontologist should attend the pre-construction
meeting to consult with the grading and excavation contractors concerning excavation
schedules, paleontological field techniques, and safety issues.
3. During construction (monitoring): A paleontological monitor (working under the direction of
the Project Paleontologist) should be on-site on a full-time basis during earthwork impacting
previously undisturbed deposits of high paleontological sensitivity (e.g., Mission Valley
Formation and/or Otay Formation) and moderate paleontological sensitivity (e.g., Pleistocene-
age old alluvial flood plain deposits) to inspect exposures for unearthed fossils. It is anticipated
that these geologic units will be impacted during site grading and other miscellaneous
excavations occurring at or below finished grade (e.g., storm drain excavations, trenching for
subgrade utilities and foundations, grading of driveways). Monitoring may be reduced or
terminated at the discretion of the Project Paleontologist based on the results of initial
monitoring.
4. During construction (fossil recovery): If fossils are discovered, the Project Paleontologist (or
paleontological monitor) should recover them. In most cases, fossil recovery can be completed
in a short period of time. However, some fossil specimens (e.g., a bone bed or a complete large
mammal skeleton) may require an extended recovery period. In these instances, the Project
Paleontologist (or paleontological monitor) has the authority to temporarily direct, divert, or
halt grading to allow recovery of fossil remains in a timely manner.
5. Post-construction (treatment): Fossil remains collected during monitoring and recovery should
be cleaned, repaired, sorted, and cataloged as part of the mitigation program.
6. Post-construction (curation): Prepared fossils, along with copies of all pertinent field notes,
photos, and maps, should be deposited (as a donation) in the designated fossil repository.
Donation of the fossils shall be accompanied by financial support for initial specimen processing
and storage.
7. Post-construction (final report): A final summary paleontological mitigation report should be
completed that outlines the results of the mitigation program. This report should include
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 13
discussions of the methods used, stratigraphic section(s) exposed, fossils collected, inventory
lists of catalogued fossils, and significance of recovered fossils.
5.0 References
Chandler, R.M. 1982. A second record of Pleistocene passenger pigeons from California. Condor 84: 242.
City of Chula Vista. 2019. “City Limit” [feature service]. Last updated April 19, 2019.
https://gisweb.chulavistaca.gov/arcgis/rest/services/opendata/administrative/MapServer/0
(January 5, 2022).
Cohen, K.M., S.C. Finney, P.L. Gibbard, J.-X. Fan. 2021. The ICS International Chronostratigraphic Chart.
Episodes 36: 199–204.
Deméré, T.A. 1986. EastLake: A new chapter in the geologic history of San Diego County. Environment
Southwest 515: 9-13.
Deméré, T.A. 1988. Early Arikareean (late Oligocene) vertebrate fossils and biostratigraphic correlations
of the Otay Formation at EastLake, San Diego County, California. In, M.V. Filewicz and R.L.
Squires (eds.), Paleogene Stratigraphy, West Coast of North America. Society of Economic
Paleontologists and Mineralogists, Pacific Section 58: 35-43.
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, 68 p.
Deméré, T.A., K.A. Randall, B.O. Riney, and S.A. Siren. 2013. Discovery of remains of an extinct giant
bison (Bison latifrons) in upper Pleistocene (Rancholabrean) fluvial strata in the San Luis Rey
River Valley, San Diego County, California, USA. In, B.J. Olson (ed.) San Luis Rey on Display:
geoscience in northern San Diego County. San Diego Association of Geologists 2013 Field Trip
Guidebook. Sunbelt Publications, San Diego. pp. 123–144.
Esri. 2021. “World Topographic Map” [basemap]. Updated August 2, 2021.
https://www.arcgis.com/home/item.html?id=30e5fe3149c34df1ba922e6f5bbf808f. (January 5,
2022).
Geocon, Inc. 2021. Preliminary Geotechnical Investigation, Nirvana Industrial Buildings and Self Storage
Complex, 821 Main Street, Chula Vista, California. Prepared for OnPoint Development. Dated 14
September 2021.
Givens, C.R., and M.P. Kennedy. 1979. Eocene molluscan stages and their correlation, San Diego area,
California. In, P.L. Abbott (ed.), Eocene Depositional Systems, San Diego. Geological Society of
America, fieldtrip guidebook, pp. 81-95.
Golz, D.J., and J.A. Lillegraven. 1977. Summary of known occurrences of terrestrial vertebrates from
Eocene strata of southern California. University of Wyoming, Contributions to Geology 15: 43–
64.
Guthrie, D.A. 2012. Avian material from Rancho del Oro, a Pleistocene locality in San Diego County,
California. Bulletin of the Southern California Academy of Sciences, 109(1).
Hanna, M.A. 1926. Geology of the La Jolla quadrangle, California. University of California Publications in
Geological Sciences 16: 187-246.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 14
Hoffman, J.M., and D.R. Prothero. 2004. Revision of the late Oligocene dwarfed leptauchenine oreodont
Sespia (Mammalia: Artiodactyla). In, S.G. Lucas, K.E. Ziegler, and P.E. Kondrashov (eds.),
Paleogene mammals. New Mexico Museum of Natural History and Science, Bulletin 26: 155-164.
Jefferson, G.T. 1991. A catalog of late Quaternary vertebrates from California. Natural History Museum
of Los Angeles County, Technical Reports 7: 1–129.
Kennedy, M.P. 1975. Geology of the San Diego metropolitan area, California. Section A - Western San
Diego metropolitan area. California Division of Mines and Geology, Bulletin 200: 9-39.
Kennedy, M.P., and G.W. Moore. 1971. Stratigraphic relations of upper Cretaceous and Eocene
formations, San Diego coastal area, California. American Association of Petroleum Geologists,
Bulletin 55: 709-722.
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:
42-56.
Kennedy, M.P., and S.S. Tan. 1977. Geology of National City, Imperial Beach, and Otay Mesa
quadrangles, southern San Diego metropolitan area, California. California Division of Mines and
Geology, Map Sheet 29, 1:24,000 scale.
Kennedy, M.P., and S.S. Tan. 2008. Geologic map of the San Diego 30' x 60' quadrangle, California.
California Geological Survey, Regional Geologic Map Series 1:100,000 scale, map no. 3.
Majors, C.P. 1993. Preliminary report on a late Pleistocene vertebrate assemblage from Bonita, San
Diego County, California. In, R.G. Dundas and D.J. Long (eds.), New Additions to the Pleistocene
Vertebrate Record of California. PaleoBios 15: 63–77.
May, J.A. 1985. Submarine-canyon system of the Eocene San Diego embayment. In, P.L. Abbott (ed.), On
the Manner of Deposition of the Eocene Strata in Northern San Diego County. San Diego
Association of Geologists Guidebook: 1–18.
May, J.A., and J.E. Warme.1991. Marine sedimentology of the early to middle Eocene La Jolla Group. In,
P.L. Abbott and J.A. May (eds.), Eocene Geologic History San Diego Region. Pacific Section SEPM
68: 73–88.
Murphey, P.C., G.E. Knauss, L. H. Fisk, T.A. Deméré, and R.E. Reynolds. 2019. Best practices in mitigation
paleontology. San Diego Society of Natural History, Proceedings 47: 1-43.
PaleoServices, San Diego Natural History Museum. 2015. Paleontological Identification Report,
Paleontological Evaluation Report, Paleontological Mitigation Plan, Proposed Project Federal
ID#BRLS 5203(039), City of Chula Vista, San Diego County, California. Prepared for BRG
Consulting, dated 18 December 2015.
Peterson, G.L., and M.P. Kennedy. 1974. Lithostratigraphic variations in the Poway Group near San
Diego, California. San Diego Society of Natural History, Transactions 17: 251-258.
Prothero, D.R., and C.A. Lubar. 2016. Fossil camels from the late Oligocene EastLake Local Fauna, Otay
Formation, San Diego County, California. In, R.M. Sullivan and S.G. Lucas (eds.), Fossil Record 5.
New Mexico Museum of Natural History and Science, Bulletin 74: 213-221.
San Diego Natural History Museum (SDNHM), unpublished paleontological collections data and field
notes.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report 15
Society of Vertebrate Paleontology (SVP). 2010. Standard Procedures for the Assessment and Mitigation
of Adverse Impacts to Paleontological Resources. Society of Vertebrate Paleontology, p. 1-11.
Stephenson, B., and seven others. 2009. County of San Diego Guidelines for Determining Significance of
Paleontological Resources. Land Use and Environment Group, Department of Planning and Land
Use, Department of Public Works, 46 p.
Walsh, S.L. 1996. Middle Eocene mammal faunas of San Diego County, California. In, D.R. Prothero and
R.J. Emry (eds.). The Terrestrial Eocene-Oligocene Transition in North America. Cambridge
University Press: 75–119.
Walsh, S.L., and T.A. Deméré. 1991. Age and stratigraphy of the Sweetwater and Otay Formations, San
Diego County, California. In, P.L. Abbott and J.A. May (eds.), Eocene Geologic History San Diego
Region. Society of Economic Paleontologists and Mineralogists, Pacific Section 68: 131-148.
Walsh, S.L., D.R. Prothero, and D.J. Lundquist. 1996. Stratigraphy and paleomagnetism of the middle
Eocene Friars Formation and Poway Group, southwestern San Diego County, California. In, D.R.
Prothero and R.J. Emry (eds.), The Terrestrial Eocene-Oligocene Transition in North America.
Cambridge University Press: 120–154.
Nirvana Industrial Buildings and Self Storage Complex—Paleontological Resources Technical Report A1
Appendix A
List of SDNHM fossil collection localities in the vicinity of the Project site.
Appendix A: Locality List
San Diego Natural History Museum
Department of Paleontology
Locality Number Locality Name Location Elevation (feet)Geologic Unit Era Period Epoch
6699 Flat Rock City of Chula Vista, San Diego County, California 171 Bay Point Formation, unnamed nonmarine deposit Cenozoic Quaternary late Pleistocene
4752 Dennery Ranch Road Cut San Diego County, California 120 Mission Valley Formation Cenozoic Paleogene middle Eocene
5648 Sunroad Auto Park City of Chula Vista, San Diego County, California 90 Mission Valley Formation Cenozoic Paleogene middle Eocene
4264 Dennery Ranch City of San Diego, San Diego County, California 275 Otay Formation, gritstone member Cenozoic Paleogene late Oligocene
5411 Hidden Trails City of San Diego, San Diego County, California 280 Otay Formation, gritstone member Cenozoic Paleogene late Oligocene
6051 Otay Landfill Canyon 3, Phase 3C San Diego County, California 398 Otay Formation, sandstone-mudstone member Cenozoic Paleogene late Oligocene
6050 Otay Landfill Canyon 3, Phase 3C San Diego County, California 350 Otay Formation, sandstone-mudstone member Cenozoic Paleogene late Oligocene
4857 Otay Landfill Canyon 3 Phase 3A, Microsite San Diego County, California 412 Otay Formation, sandstone-mudstone member Cenozoic Paleogene Oligocene
7594 Otay Ranch Village 2 South City of Chula Vista, San Diego County, California 406 Otay Formation, sandstone-mudstone member Cenozoic Paleogene late Oligocene
7599 Otay Ranch Village 2 South City of Chula Vista, San Diego County, California 470 Otay Formation, sandstone-mudstone member Cenozoic Paleogene late Oligocene
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