HomeMy WebLinkAboutCUP 2018-0014; FIRE STATION NO.2; GEOTECHNICAL EVALUATION; 2017-10-18
Geotechnical Evaluation
Fire Station No. 2
1906 Arenal Road
Carlsbad, California
domusstudio architecture
2150 West Washington Street, Suite 303 | San Diego, California 92110
October 18, 2017 | Project No. 108438001
Geotechnical | Environmental | Construction Inspection & Testing | Forensic Engineering & Expert Witness
Geophysics | Engineering Geology | Laboratory Testing | Industrial Hygiene | Occupational Safety | Air Quality | GIS
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 i
CONTENTS
1 INTRODUCTION 1
2 SCOPE OF SERVICES 1
3 SITE DESCRIPTION AND BACKGROUND 2
4 PROJECT DESCRIPTION 2
5 SUBSURFACE EVALUATION AND LABORATORY TESTING 3
6 INFILTRATION TESTING 3
7 GEOLOGIC AND SUBSURFACE CONDITIONS 4
7.1 Regional Geologic Setting 4
7.2 Site Geology 5
7.2.1 Fill 5
7.2.2 Old Alluvium 5
7.2.3 Santiago Formation 6
7.3 Groundwater 6
8 GEOLOGIC HAZARDS 6
8.1 Faulting and Seismicity 6
8.2 Surface Ground Rupture 7
8.3 Liquefaction and Seismically Induced Settlement 7
8.4 Strong Ground Motion 7
9 CONCLUSIONS 8
10 RECOMMENDATIONS 9
10.1 Earthwork 9
10.1.1 Site Preparation 9
10.1.2 Temporary Excavations 10
10.1.3 Excavation Characteristics 10
10.1.4 Remedial Grading – Building Pad 10
10.1.5 Remedial Grading – Retaining and Site Walls 11
10.1.6 Remedial Grading – Concrete Pedestrian Flatwork 12
10.1.7 Remedial Grading – Vehicular Pavements 13
10.1.8 Fill Material 13
10.1.9 Compacted Fill 14
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10.1.10 Pipe Bedding and Modulus of Soil Reaction 14
10.1.11 Utility Trench Backfill 15
10.1.12 Thrust Blocks 15
10.2 Seismic Design Considerations 15
10.3 Foundations 16
10.3.1 Shallow Footings 16
10.3.2 Lateral Resistance 17
10.3.3 Static Settlement 17
10.3.4 Interior Concrete Slabs-on-Grade 17
10.4 Site Retaining Walls 18
10.5 Light Pole and Canopy Foundations 18
10.6 Preliminary Pavement Design 19
10.6.1 Preliminary Flexible Pavements Design 19
10.6.2 Preliminary Concrete Pavement Design 20
10.6.3 Exterior Concrete Flatwork 20
10.7 Corrosivity 21
10.8 Concrete 21
10.9 Drainage 22
10.10 Infiltration Devices 22
10.11 Pre-Construction Conference 22
10.12 Plan Review and Construction Observation 22
11 LIMITATIONS 23
12 REFERENCES 25
TABLES
1 – Infiltration Test Results Summary 4
2 – Principal Active Faults 7
3 – 2016 California Building Code Seismic Design Criteria 16
4 – Recommended Preliminary Flexible Pavement Sections 20
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FIGURES
1 – Site Location
2 – Boring Locations
3 – Fault Locations
4 – Geology
5 – Cross Section A-A’
6 – Thrust Block Lateral Earth Pressure Diagram
7 – Lateral Earth Pressures for Yielding Retaining Walls
8 – Lateral Earth Pressures for Non-Yielding Retaining Walls
9 – Retaining Wall Drainage Detail
APPENDICES
A – Boring Logs
B – Laboratory Testing
C – Infiltration Testing and Worksheet I-8
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 1
1 INTRODUCTION
In accordance with your request, we have performed a geotechnical evaluation for the proposed
new Fire Station No. 2 to be constructed at 1906 Arenal Road in Carlsbad, California (Figure 1).
Our evaluation was performed in accordance with our proposal dated July 21, 2017. The
objectives of this study were to assess the prevailing soil conditions at the site, evaluate the
engineering properties of the soils encountered, and provide recommendations relative to the
geotechnical aspects of the proposed project. This report presents the results of our field
explorations and laboratory testing as well as our conclusions regarding the geotechnical conditions
at the site and our recommendations for the design and construction of this project.
2 SCOPE OF SERVICES
The scope of services for this study included the following:
Review of readily available published and in-house geotechnical literature, topographic
maps, geologic maps, fault maps, and stereoscopic aerial photographs.
Performance of a field reconnaissance to observe site conditions and to locate and mark
the exploratory borings.
Notification of Underground Service Alert (USA) to clear the boring locations for the
potential presence of underground utilities.
Performance of a subsurface evaluation consisting of drilling, logging, and sampling of four
exploratory borings. Bulk and in-place soil samples were obtained at selected intervals from
within the borings. The collected samples were transported to our in-house geotechnical
laboratory for analysis.
Performance of infiltration testing within one of the exploratory borings.
Performance of geotechnical laboratory testing on representative samples to evaluate soil
characteristics and design parameters.
Compilation and analysis of the data obtained from our background review, subsurface
evaluation, and laboratory testing.
Preparation of this report presenting our findings, conclusions, and recommendations
regarding the geotechnical design and construction aspects of the project.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 2
3 SITE DESCRIPTION AND BACKGROUND
Fire Station No. 2 is located on an irregularly-shaped parcel at 1906 Arenal Road, Carlsbad
California. The site is bounded by El Camino Real to the west, Arenal Road to the south, and
private residences to the northeast. The site coordinates are approximately 33.09470 N latitude
and -117.26740 W longitude.
Currently, the site consists of the existing Fire Station No. 2, concrete pavements, an asphalt-
concrete (AC) paved parking lot, several retaining and block walls, and landscaped areas. The
ground elevation at the site slopes gently from approximately 90 feet above mean sea
level (MSL) in the northern portion of the site to approximately 85 feet above MSL in the
southern portion of the site.
Based on reports prepared by MV Environmental, Inc. (1991a, 1991b, and 1991c), a
leaking, 500-gallon, gasoline-underground storage tank (UST) was removed from the site on
March 5, 1990. Due to observed staining beneath the tank, an unauthorized release case
was opened (H24732-001/T0166). According to the maps contained in the referenced
reports, the tank was located in the driveway to the east of the existing fire station building.
Subsequent work at the site included sampling and testing of contaminated soils. According
to the County of San Diego Department of Environmental Health (DEH) Closure Report
(1991a), soil impacted with contaminants of concern (COCs) was removed from the area of
the former tank and confirmation sampling indicated remaining soil was non-detect for
COCs. According to the referenced MV Environmental Inc. reports (1991a, 1991b, and
1991c), the former UST and over-excavation area was filled with non-contaminated fill soils.
The case was closed by the San Diego Department of Environmental Health on June 4,
1991 (County of San Diego DEH, 1991b). The extent of the soil removal area is anticipated
to be approximately 13 feet by 12 feet and extends to a depth of approximately 9 feet.
Compaction testing reports for the backfilled soil were not available.
4 PROJECT DESCRIPTION
Based on our review of conceptual plans prepared by WLC Architect (2016) and discussions
with the client, we understand that the existing fire station building will be demolished and
replaced with a new building. The new Fire Station No. 2 will include a two-story structure with
living spaces and dormitories situated over the apparatus bay. A parking lot and a wrap-around
driveway will be situated on the north and east sides of the building. Although structural plans
were not available for our review, we anticipate that the proposed building will be supported on
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 3
conventional shallow concrete foundations with an interior concrete slab-on-grade floor. Further
improvements are anticipated to include site retaining walls, site screen walls, emergency
generator pads, a trash enclosure, and underground utilities.
5 SUBSURFACE EVALUATION AND LABORATORY TESTING
Our subsurface exploration at the site was performed on August 30 and 31, 2017, and included
the drilling, logging, and sampling of four small-diameter borings (B-1 through B-3 and IT-1) to
depths of up to approximately 20 feet. Borings B-1 through B-3 were drilled using a
truck-mounted drill rig equipped with 8-inch diameter hollow-stem augers. Boring IT-1 was
manually excavated to a depth of approximately 5 feet and was used for infiltration testing. Bulk
and in-place soil samples were obtained from the borings at selected intervals. The samples
were then transported to our in-house geotechnical laboratory for testing. The approximate
locations of the exploratory borings and the infiltration test are shown on Figure 2. The logs of
the exploratory borings are presented in Appendix A.
Laboratory testing of representative soil samples included the performance of tests to evaluate
in-situ moisture content and dry density, gradation (sieve) analysis, shear strength, expansion
index, soil corrosivity, and R-value. The results of our in-situ moisture content and dry density
tests are presented on the boring logs in Appendix A. The results of the other laboratory tests
are presented in Appendix B.
6 INFILTRATION TESTING
On August 30 and 31, 2017, one exploratory boring (IT-1) was manually excavated to evaluate the
infiltration characteristics of the site. The boring was manually excavated to a depth of approximately
5 feet. Following excavation, infiltration testing was performed in the boring. The infiltration test was
performed in general accordance with the City of Carlsbad BMP Design Manual (2016).
Approximately 2 inches of gravel was placed on the bottom of the prepared boring. Then, a 2-inch-
diameter, perforated PVC pipe was installed in the boring and the annulus was then backfilled with
pea gravel. As part of the test procedure, a presoak was performed to represent adverse conditions
for infiltration. The presoak consisted of maintaining an approximately 1 foot column of water in the
boring for approximately 4 hours. The water level was then allowed to drop overnight. Infiltration
testing was performed on August 31, 2017 in the presoaked boring. The boring was filled with
approximately 1 foot of water and measurements of the water depth were generally recorded every
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 4
30 minutes until consistent measurements were obtained. The boring was re-filled as needed to
maintain the water level until the infiltration rate stabilized.
The infiltration rate from our testing in boring IT-1 was then calculated using the Porchet
method. The adjusted infiltration test result was approximately 0.28 inches per hour (in/hr). The
infiltration test measurements and calculations are included in Appendix C, and the result is
summarized in Table 1 below.
Table 1 – Infiltration Test Results Summary
Infiltration Test
(depth)
Soil Description at Test Depth
(Geologic Unit)
Infiltration Rate
(in/hr)
IT-1
(5.0 feet)
Sandy CLAY
(Fill) 0.28
Based on the City of Carlsbad BMP Design Manual (2016), infiltration rates of less than
0.5 inches per hour may be suitable for partial infiltration and infiltration rates of 0.5 inches per
hour or greater per hour may be considered suitable for full infiltration design. The infiltration
rates presented above are based on in-situ testing (i.e., factor of safety of 1.0). The design
engineer should evaluate and apply an appropriate factor of safety when designing the
improvements. The City of Carlsbad BMP Design Manual (2016) provides additional discussion
and considerations for applying an infiltration factor of safety.
7 GEOLOGIC AND SUBSURFACE CONDITIONS
7.1 Regional Geologic Setting
The project area is situated in the coastal foothill section of the Peninsular Ranges Geomorphic
Province. This geomorphic province encompasses an area that extends approximately 900
miles from the Transverse Ranges and the Los Angeles Basin south to the southern tip of Baja
California (Norris and Webb, 1990; Harden, 2004). The province varies in width from
approximately 30 to 100 miles. In general, the province consists of rugged mountains underlain
by Jurassic metavolcanic and metasedimentary rocks, and Cretaceous igneous rocks of the
southern California batholith. The portion of the province that includes the project area generally
consists of Tertiary- and Quaternary-age sedimentary rocks.
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The Peninsular Ranges Province is traversed by a group of sub-parallel faults and fault zones
trending approximately northwest. Several of these faults, shown on Figure 3, are considered
active faults. The Elsinore, San Jacinto, and San Andreas faults are active fault systems located
northeast of the project area and the Rose Canyon, Coronado Bank, San Diego Trough, and San
Clemente faults are active faults located southwest of the project area. The Rose Canyon Fault
Zone, the nearest active fault system, has been mapped approximately 5.7 miles southwest of the
project site. Major tectonic activity associated with these and other faults within this regional
tectonic framework consists primarily of right-lateral, strike-slip movement. Further discussion of
faulting relative to the site is provided in the Faulting and Seismicity section of this report.
7.2 Site Geology
The results of our geologic reconnaissance and subsurface evaluation indicate that the site is
generally underlain by artificial fill, old alluvium, and materials of the Santiago Formation
(Kennedy and Tan, 2007) as shown on Figure 4. Generalized descriptions of the materials
encountered during our subsurface exploration are presented below. More detailed descriptions
of the materials encountered in our exploratory borings are shown on the boring logs in
Appendix A. A geologic cross section for the site is presented on Figure 5.
7.2.1 Fill
Fill materials were encountered in each of our borings at the ground surface or underlying the
pavement sections and extending to depths of up to approximately 10 feet. Additionally, as
previously noted in the background section of this report, fills on the order of approximately
9 feet deep are also anticipated in the area of the UST removal. As encountered in our
borings, the fill materials generally consisted of various shades of brown, moist, medium
dense, silty and clayey sand, and stiff to firm, sandy clay. Scattered roots, gravel, shells and
shell fragments, and concrete fragments were encountered in the fill materials.
7.2.2 Old Alluvium
Quaternary-age old alluvial flood plain deposits were encountered in boring B-1 below the
fill materials to a depth of up to approximately 3½ feet. As encountered, these materials
generally consisted of brown, dry to moist, medium dense, silty fine sand.
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7.2.3 Santiago Formation
Materials of the Eocene-age Santiago Formation were encountered in borings B-1 through
B-3 below the fill and alluvium to the total depths explored. As encountered, these materials
generally consisted of various shades of brown to gray, moist, weakly to strongly
cemented, clayey and silty sandstone. Scattered manganese deposits, iron oxide staining,
and caliche were encountered in the formational materials.
7.3 Groundwater
Groundwater was not encountered in our exploratory borings at the site. Our review of
groundwater monitoring well data in the site vicinity indicates that groundwater is present at a
depth greater than 20 feet below ground surface. Fluctuations in the level of groundwater may
occur due to variations in ground surface topography, subsurface stratification, rainfall, irrigation
practices, groundwater pumping, and other factors which may not have been evident at the time
of our field evaluation.
8 GEOLOGIC HAZARDS
8.1 Faulting and Seismicity
The subject site is not located within a State of California Earthquake Fault Zone (formerly
known as Alquist-Priolo Special Studies Zone) (Hart and Bryant, 1997). However, the site is
located in a seismically active area, as is the majority of southern California, and the potential
for strong ground motion in the project areas is considered significant during the design life of
the proposed improvements. The approximate locations of major faults in the region and their
geographic relationship to the site are shown on Figure 3.
Table 2 lists selected principal known active faults that may affect the subject site and the
maximum moment magnitude (Mmax) as published by the United States Geological Survey
(USGS, 2017a). The approximate fault-to-site distances were calculated using the USGS fault
parameters web-based design tool (USGS, 2017b).
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Table 2 – Principal Active Faults
Fault
Approximate
Fault-to-Site Distance
miles (kilometers)
Maximum Moment
Magnitude
(Mmax)
Rose Canyon 5.7 (9.1) 6.9
Newport-Inglewood (Offshore) 10.3 (16.5) 7.0
Coronado Bank 21.2 (34.1) 7.4
Elsinore (Julian) 22.6 (36.3) 7.35
Elsinore (Temecula) 22.6 (36.3) 7.07
Elsinore (Glen Ivy) 36.6 (58.9) 6.89
Earthquake Valley 39.9 (64.2) 6.8
San Joaquin Hills 41.8 (67.2) 7.1
San Jacinto (Anza) 47.8 (76.9) 7.28
San Jacinto (Coyote Creek) 49.2 (79.1) 7.03
San Jacinto (San Jacinto Valley) 50.2 (80.7) 7.04
8.2 Surface Ground Rupture
Based on our review of the referenced literature and our site reconnaissance, no active faults
are known to cross the project site. The active Rose Canyon Fault Zone is located
approximately 5.7 miles southwest of the site. Therefore, the probability of damage from surface
ground rupture is considered to be low. However, lurching or cracking of the ground surface as a
result of nearby seismic events is possible.
8.3 Liquefaction and Seismically Induced Settlement
Liquefaction of cohesionless soils can be caused by strong vibratory motion due to earthquakes.
Research and historical data indicate that loose granular soils and non-plastic silts that are saturate
by a relatively shallow groundwater table are susceptible to liquefaction. Based on the relatively
dense nature of the underlying formational materials, it is our opinion that the potential for
liquefaction and seismically induced settlement to occur at the site is not a design consideration.
8.4 Strong Ground Motion
The 2016 California Building Code (CBC) specifies that the Risk-Targeted, Maximum
Considered Earthquake (MCER) ground motion response accelerations be used to evaluate
seismic loads for design of buildings and other structures. The MCER ground motion response
accelerations are based on the spectral response accelerations for 5 percent damping in the
direction of maximum horizontal response and incorporate a target risk for structural collapse
equivalent to 1 percent in 50 years with deterministic limits for near-source effects. The
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 8
horizontal peak ground acceleration (PGA) that corresponds to the MCER for the site was
calculated as 0.43g using the USGS (USGS, 2017b) seismic design tool (web-based).
The 2016 CBC specifies that the potential for liquefaction and soil strength loss be evaluated, where
applicable, for the Maximum Considered Earthquake Geometric Mean (MCEG) peak ground
acceleration with adjustment for site class effects in accordance with the American Society of Civil
Engineers (ASCE) 7-10 Standard. The MCEG peak ground acceleration is based on the geometric
mean peak ground acceleration with a 2 percent probability of exceedance in 50 years. The MCEG
peak ground acceleration with adjustment for site class effects (PGAM) was calculated as 0.42g
using the USGS (2017b) seismic design tool that yielded a mapped MCEG peak ground acceleration
of 0.42g for the site and a site coefficient (FPGA) of 1.0 for Site Class C.
9 CONCLUSIONS
Based on our geotechnical evaluation, it is our opinion that construction of the proposed new
Fire Station No. 2 at the subject site is feasible from a geotechnical standpoint, provided the
following recommendations are incorporated into the design and construction of the project.
The site is generally underlain by fill soils and old alluvium that were encountered to depths
up to approximately 10 feet. These materials were further underlain by materials of the
Santiago Formation.
The existing fill materials and the old alluvium are generally not considered suitable for
support of structures in their current condition. Recommendations for the remedial grading
of these materials are presented in the following sections.
Excavations during site grading should be generally feasible with earthmoving equipment in
good working order. Due to the variability of weathering in the Santiago Formation materials
and potential for hard zones, hard materials should be anticipated that may result in
oversize material and difficult excavation during construction of the recommended retaining
wall foundation. Special excavating equipment, such as rippers, pneumatic chippers or
jackhammers may be anticipated.
Existing fill materials are not anticipated to be utilized within the upper 3 feet of the building pad.
Based on the laboratory testing presented in Appendix B, the on-site materials possess a
low to medium potential for expansion. Accordingly, the following sections provide
recommendations for remedial grading operations that include the placement of very low
expansion materials within a portion of the building pad and low expansion materials
beneath concrete flatwork and behind retaining walls. The contractor should anticipate
partially exporting on-site materials and replacing them with import fill materials.
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Although groundwater was not encountered during our subsurface exploration, the depth to
groundwater varies due to seasonal precipitation, subsurface conditions, irrigation,
groundwater pumping, and other factors. Seepage and fluctuations in the groundwater
levels at the site should be anticipated.
The site is not located within a State of California Earthquake Fault Zone (formerly Alquist-
Priolo Special Studies Zone). Based on our review of published geologic maps and aerial
photographs, no known active or potentially active faults underlie the site. The potential for
surface fault rupture at the site is considered to be low.
Field infiltration testing indicated an infiltration rate 0.28 inches per hour based on a factor
of safety of 1.0. However, an appropriate factor of safety should be applied to the measured
infiltration rates during design.
10 RECOMMENDATIONS
Based on our understanding of the project, the following recommendations are provided for the
design and construction of the proposed fire station. The proposed site improvements should be
constructed in accordance with the requirements of the applicable governing agencies.
10.1 Earthwork
In general, earthwork should be performed in accordance with the recommendations presented
in this report. Ninyo & Moore should be contacted for questions regarding the recommendations
or guidelines presented herein.
10.1.1 Site Preparation
Site preparation should begin with the removal of flatwork, vegetation, utility lines, asphalt,
concrete, and other deleterious debris from areas to be graded. Obstructions that extend
below the finished grade (such as tree stumps) should be removed to such a depth that
organic material is generally not present and the resulting holes filled with compacted soil.
Clearing and grubbing should extend to the outside of the proposed excavation and fill
areas. The debris and unsuitable material generated during clearing and grubbing should
be removed from areas to be graded and disposed of at a legal dumpsite away from the
project area.
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10.1.2 Temporary Excavations
For temporary excavations, we recommend that the following Occupational Safety and
Health Administration (OSHA) soil classifications be used:
Fill Type C
Santiago Formation Type B
Upon making the excavations, the soil classifications and excavation performance should
be evaluated in the field by the geotechnical consultant in accordance with the OSHA
regulations. Temporary excavations should be constructed in accordance with OSHA
recommendations. For trench or other excavations, OSHA requirements regarding
personnel safety should be met using appropriate shoring (including trench boxes) or by
laying back the slopes to no steeper than 1.5:1 (horizontal to vertical) in fill and 1:1 in the
Santiago Formation materials. Temporary excavations that encounter seepage may be
shored or stabilized by placing sandbags or gravel along the base of the seepage zone.
Excavations encountering seepage should be evaluated on a case-by-case basis. On-site
safety of personnel is the responsibility of the contractor.
10.1.3 Excavation Characteristics
Based on our exploratory borings and review of geologic background materials, we
anticipate that excavation of the fill, old alluvium, and formational materials present on site
may generally be accomplished with heavy-duty grading equipment in good operating
condition. We anticipate that the formational materials will generally disaggregate and/or
break down with processing to be reused as fill. However, based on our experience, the
degrees of weathering, decomposition, and hardness of the formational materials may vary
widely with relatively abrupt changes on a site. Formational materials with lesser degrees of
weathering may involve special excavating equipment, such as rippers, pneumatic
chippers, or jackhammers. Excavations in lees weathered zones of the formational
materials may generate oversize fragments that are not generally suitable for fill material.
10.1.4 Remedial Grading – Building Pad
The existing fills and old alluvium are considered compressible and not suitable for structural
support in their present condition. Additionally, we anticipate that the new fire station building
may straddle a cut/fill transition. Accordingly, we recommend overexcavating the building pad to
the limits described below and backfilling the resulting excavation with compacted fill soils. For
the purposes of this report, the building pad is defined as the structural footprint (including
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foundations for attached stairwells, overhangs, canopies, and other building appurtenances)
plus a horizontal distance of 5 feet, where feasible.
We recommend that the existing near-surface materials (fill and old alluvium) within the
building pad be removed down to competent materials of the Santiago Formation, or to a
depth of 3 feet below the bottom of footings, whichever is deeper. This over excavation
should extend to the horizontal limits of the building pad as previously defined, where
feasible. The lateral extents of the overexcavation may be modified in the field based on
site constraints such as existing structures and property lines. The extent and depths of
removals and overexcavations should be evaluated by Ninyo & Moore’s representative in
the field based on the materials exposed.
The resulting removal surface should be scarified to a depth of approximately 8 inches,
moisture conditioned, and recompacted to a relative compaction of 90 percent as evaluated
by the ASTM International (ASTM) Test Method D 1557 prior to placing new compacted fill.
Once the resulting removal surface has been recompacted, the portion of the overexcavation
that is deeper than 3 feet below the finished building pad subgrade elevation should be
backfilled with on-site soils that possess a very low to medium potential (i.e., an expansion
index [EI] less than 90). The upper 3 feet of soils beneath the finished building pad subgrade
elevation should be backfilled with soils that possess a very low potential for expansion (i.e.,
an expansion index [EI] less than 20). These compacted fill soils should be placed at a
relative compaction of 90 percent as evaluated by ASTM D 1557.
Note, the on-site soils possess a low to medium potential for expansion. The materials that
possess an expansion index great than 20 are not suitable for reuse as compacted fill
within the upper 3 feet of finished building pad subgrade elevation. It is anticipated that the
upper 3 feet of compacted fill beneath the finished building pad subgrade elevation will
consist of imported materials.
10.1.5 Remedial Grading – Retaining and Site Walls
In the foundation areas for site retaining and screen walls, we recommend that the on-site soils
beneath the wall foundations be overexcavated to a depth of 1 foot below the bottom of the
foundations. The proposed overexcavations should extend outward horizontally 2 feet from the
exterior limits of the wall foundation, where feasible. The extent and depth of removals should
be evaluated by Ninyo & Moore’s representative in the field based on the material exposed.
The resulting surface should be scarified 6 inches, moisture conditioned, and recompacted to a
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relative compaction of 90 percent as evaluated by ASTM D 1557. The removals should then be
filled with on-site soils suitable for reuse as compacted fill.
Note, some on-site soils possess a medium potential for expansion. These materials that
possess a medium potential for expansion are not suitable for reuse as wall backfill. The
wall backfill materials may be derived from on-site soils or import soils.
10.1.6 Remedial Grading – Concrete Pedestrian Flatwork
In the proposed areas for concrete pedestrian flatwork, we recommend that the on-site
subgrade soils be scarified 8 inches, moisture conditioned, and recompacted to a relative
compaction of 90 percent as evaluated by ASTM D 1557. The proposed scarification and
recompaction should extend outward horizontally 2 feet from the exterior limits of the
hardscaping, where feasible. The extent and depth of removals should be evaluated by
Ninyo & Moore’s representative in the field based on the material exposed.
In the event the subgrade soils exposed beneath the concrete pedestrian flatwork that possess
a medium to high potential for expansion (i.e. an expansion index of 50 or more), we
recommend that those expansive soils be overexcavated and removed. We recommend that
the subgrade soils be overexcavated to a depth of 1 foot below the planned subgrade elevation
for the proposed concrete pedestrian flatwork areas. The proposed overexcavations should
extend outward horizontally 2 feet from the exterior limits of the flatwork, where feasible. The
extent and depth of removals should be evaluated by Ninyo & Moore’s representative in the
field based on the material exposed. The resulting surface should be scarified 6 inches,
moisture conditioned, and recompacted to a relative compaction of 90 percent as evaluated by
ASTM D 1557. The removals should then be filled with soils that possess a low to very low
potential for expansion (i.e. an expansion index less than 50). These compacted fill soils should
be placed at a relative compaction of 90 percent as evaluated by ASTM D 1557.
Note, some on-site soils possess a medium potential for expansion. These materials that
possess a medium potential for expansion are not suitable for reuse as compacted fill within 1
foot below the subgrade elevation of concrete pedestrian flatwork areas. The subgrade soils
beneath concrete pedestrian flatwork areas may be derived from on-site soils or import soils.
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10.1.7 Remedial Grading – Vehicular Pavements
In the proposed vehicular pavement areas, we recommend that the on-site soils be
overexcavated to a depth of 1 foot below the planned subgrade elevation for the pavement.
The proposed overexcavations should extend outward horizontally 2 feet from the exterior
limits of the pavement, where feasible. The extent and depth of removals should be evaluated
by Ninyo & Moore’s representative in the field based on the material exposed. The resulting
surface should be scarified 6 inches, moisture conditioned, and recompacted to a relative
compaction of 90 percent as evaluated by ASTM D 1557. The removals should then be filled
with on-site soils suitable for reuse as compacted fill. The upper 12 inches of the subgrade
materials should be compacted to a relative compaction of 95 percent relative density as
evaluated by the current version of ASTM D 1557.
10.1.8 Fill Material
Onsite soils with a low expansion potential and an organic content of less than 3 percent by
volume (or 1 percent by weight) are considered suitable for reuse as fill. Fill material should
not contain rocks or lumps over approximately 3 inches in diameter, and not more than
approximately 30 percent larger than ¾ inch. Oversize materials (3 inches or more in
largest diameter), if encountered, may be broken into acceptably-sized pieces, or they
should be separated from material to be used for compacted fill and removed from the site.
Imported fill materials, if needed, should generally be granular soils with very low to low
expansion potential (i.e., an expansion index of 50 or less as evaluated by ASTM D 4829).
Imported fill material should also be tested for corrosive potential and exhibit an electrical
resistivity value 1,000 ohm-centimeters (ohm-cm) or more, a chloride content of less than 500
parts per million (ppm), a sulfate content of less than 1,000 ppm, and a pH more than 5.5. The
contractor should be responsible for the uniformity of import material brought to the site. We
recommend that materials proposed for use as import fill be evaluated from a contractor’s
stockpile rather than in-place materials. Utility trench backfill material, outside the zone defined
in the following sections, should not contain rocks or lumps over approximately 3 inches in
general. In general, soils classified as silts or clays should not be used for backfill in the pipe
zone. Larger soil chunks, if generated during excavation, may be broken into acceptably sized
pieces or disposed of offsite.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 14
10.1.9 Compacted Fill
Prior to placement of compacted fill, the contractor should request an evaluation of the
exposed ground surface by Ninyo & Moore. Unless otherwise recommended, the exposed
ground surface should then be scarified to a depth of approximately 8 inches and watered
or dried, as needed, to achieve moisture contents generally above the optimum moisture
content. The scarified materials should then be compacted to a relative compaction of
90 percent as evaluated in accordance with ASTM D 1557. The evaluation of compaction
by the geotechnical consultant should not be considered to preclude any requirements for
observation or approval by governing agencies. It is the contractor's responsibility to notify
this office and the appropriate governing agency when project areas are ready for
observation, and to provide reasonable time for that review.
Fill materials should be moisture conditioned to generally at or just above the laboratory
optimum moisture content prior to placement and should be generally consistent within the
soil mass. The optimum moisture content will vary with material type and other factors.
Prior to placement of additional compacted fill material following a delay in the grading
operations, the exposed surface of previously compacted fill should be prepared to receive
fill. Preparation may include scarification, moisture conditioning, and recompaction.
Compacted fill should be placed in horizontal lifts of approximately 8 inches in loose
thickness. Prior to compaction, each lift should be watered or dried as needed to achieve a
moisture content generally above the laboratory optimum, mixed, and then compacted by
mechanical methods, to a relative compaction of 90 percent as evaluated by ASTM D 1557.
Successive lifts should be treated in a like manner until the desired finished grades are
achieved. The upper 12 inches of the subgrade and aggregate base materials underneath
pavement should be compacted to a relative compaction of 95 percent relative density as
evaluated by the current version of ASTM D 1557.
10.1.10 Pipe Bedding and Modulus of Soil Reaction
We recommend that new pipelines, where constructed in open excavations, be supported
on 6 or more inches of granular bedding material. Granular pipe bedding should be
provided to distribute vertical loads around the pipe. Pipe bedding should have a Sand
Equivalent (SE) of 30 or greater and be placed around the sides and the crown of the pipe.
In keeping with the Standard Specifications for Public Works Construction (Public Works
Standards, 2015) and local utility guidelines, the pipe bedding material should extend 1 foot
or more above the crown of the pipe. The bedding material should be moisture-conditioned
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 15
to at or just above the laboratory optimum and compacted to 90 percent relative
compaction as evaluated by ASTM D 1557. Bedding material and its placement/compaction
should be in accordance with the recommendations of this report, the project specifications,
and applicable requirements of the appropriate governing agency.
The modulus of soil reaction is used to characterize the stiffness of soil backfill placed at
the sides of buried flexible pipes for the purpose of evaluating deflection caused by the
weight of the backfill over the pipe (Hartley and Duncan, 1987). A soil reaction modulus of
1,200 pounds per square inch (psi) may be used for an excavation depth of up to about
5 feet when backfilled with granular soil compacted to a relative compaction of 90 percent
as evaluated by the ASTM D 1557. A soil reaction modulus of 1,800 psi may be used for
trenches deeper than 5 feet.
10.1.11 Utility Trench Backfill
Utility trench zone backfill material should be generally free of trash, debris, roots,
vegetation, or deleterious materials. Trench zone backfill should generally be free of rocks
or hard lumps of material in excess of 3 inches in diameter. Rocks or hard lumps larger than
about 3 inches in diameter should be broken into smaller pieces or should be removed from
the site. Oversize materials should be separated from material to be used as trench backfill.
Moisture conditioning (including drying and/or mixing) of existing on-site materials is
anticipated if reused as trench backfill.
10.1.12 Thrust Blocks
Thrust restraint for buried pipelines may be achieved by transferring the thrust force to the
soil outside the pipe through a thrust block. Thrust blocks may be designed using the
magnitude and distribution of passive lateral earth pressures presented on Figure 6. Thrust
blocks should be backfilled with granular backfill material and compacted following the
recommendations presented in this report.
10.2 Seismic Design Considerations
Design of the proposed improvements should be performed in accordance with the
requirements of governing jurisdictions and applicable building codes. Table 3 presents the
seismic design parameters for the site in accordance with the CBC (2016) guidelines and
adjusted MCER spectral response acceleration parameters (USGS, 2017b).
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 16
Table 3 – 2016 California Building Code Seismic Design Criteria
Seismic Design Factors Value
Site Class C
Site Coefficient, Fa 1.0
Site Coefficient, Fv 1.387
Mapped Spectral Acceleration at 0.2-second Period, Ss 1.070g
Mapped Spectral Acceleration at 1.0-second Period, S1 0.413g
Spectral Acceleration at 0.2-second Period Adjusted for Site Class, SMS 1.070g
Spectral Acceleration at 1.0-second Period Adjusted for Site Class, SM1 0.573g
Design Spectral Response Acceleration at 0.2-second Period, SDS 0.713g
Design Spectral Response Acceleration at 1.0-second Period, SD1 0.382g
10.3 Foundations
We anticipate that the new building will consist of a concrete slab-on-grade that is supported on
conventional shallow foundations. Foundations should be designed in accordance with
structural considerations and the following recommendations. In addition, requirements of the
appropriate governing jurisdictions and applicable building codes should be considered in the
design of the structures.
10.3.1 Shallow Footings
Shallow continuous or spread footings founded engineered fill (compacted in accordance
with the recommendations presented in this report) may be designed using an allowable
bearing capacity of 2,500 pounds per square foot (psf). The allowable bearing capacity
was calculated using a factor of safety of 3. The allowable bearing capacity may be
increased by one-third when considering loads of short duration such as wind or seismic
forces. Continuous and spread footings should be founded 18 inches below the lowest
adjacent grade. Continuous footings should have a width of 15 inches and isolated
spread footings should have a width of 24 inches. Footings should be reinforced in
accordance with the recommendations of the project structural engineer.
To provide consistent bearing conditions for the foundations, we recommend that no utilities,
piping, or duct banks be constructed within 1 foot of the zone of influence of the bottom of each
foundation. The zone of influence is defined by a 1:1 (horizontal to vertical) downward
projection that extends outward from the bottom outside edge of the foundation.
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10.3.2 Lateral Resistance
For resistance of footings to lateral loads bearing on engineered fill, we recommend an
allowable passive pressure of 300 psf per foot of depth be used with a value of up to
3,000 psf. This value assumes that the ground is horizontal for a distance of 10 feet, or
three multiplied by the height generating the passive pressure, whichever is more. We
recommend that the upper 1 foot of soil not protected by pavement or a concrete slab be
neglected when calculating passive resistance.
For frictional resistance to lateral loads, we recommend a coefficient of friction of 0.35 be
used between soil and concrete. These values may be increased by one-third when
considering loads of short duration such as wind or seismic forces.
10.3.3 Static Settlement
We estimate that the proposed structures, designed and constructed as recommended
herein, will undergo total settlement on the order of 1 inch. Differential settlement on the
order of ½ inch over a horizontal span of 20 feet should be expected.
10.3.4 Interior Concrete Slabs-on-Grade
We recommend that conventional, interior concrete slab-on-grade floors, underlain by
compacted fill materials of generally very low expansion potential, be 5 inches in
thickness and be reinforced with No. 3 reinforcing bars spaced 18 inches on center
each way. The reinforcing bars should be placed near the middle of the slab. As a
means to help reduce shrinkage cracks, we recommend that the slabs be provided with
crack control joints at intervals of approximately 12 feet each way, or as recommended
by the project structural engineer. The slab reinforcement and expansion joint spacing
should be designed by the project structural engineer.
If moisture sensitive floor coverings are to be used, we recommend that slabs be underlain
by a vapor retarder and capillary break system consisting of a 10-mil polyethylene (or
equivalent) membrane placed over 4 inches of medium to coarse, clean sand or pea gravel.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 18
10.4 Site Retaining Walls
Site retaining walls that are not connected to the building may be supported on continuous
footings bearing on compacted fill. The continuous footing should have a width of 18 inches or
more and the bottom of the foundation should be embedded a depth of 24 inches or more. An
allowable bearing capacity of 2,500 psf may be used for the design of site retaining wall
foundations. The allowable bearing capacity may be increased by one-third when considering
loads of short duration, such as wind or seismic forces.
For the design of a site yielding retaining wall that is not restrained against movement by rigid
corners or structural connections, lateral pressures are presented on Figure 7. Site restrained
walls (non-yielding) may be designed for lateral pressures presented on Figure 8. These
pressures assume select backfill materials that possess a very low to low potential for
expansion (i.e. an expansion index less than 50) are used and free draining conditions.
Measures should be taken to reduce the potential for build-up of moisture behind the retaining
walls. A drain should be provided behind the retaining wall as shown on Figure 9. The drain
should be connected to an appropriate outlet.
Note, some on-site soils possess a medium potential for expansion. These materials that
possess a medium potential for expansion are not suitable for reuse as wall backfill. The wall
backfill materials may be derived from on-site soils or import soils.
10.5 Light Pole and Canopy Foundations
Due to the presence of soils with a medium potential for expansion at the site, we recommend that
light pole and canopy structures be supported on cast-in-drilled-hole (CIDH) piles. Light pole structures
typically impose relatively light axial loads on foundations. Although we anticipate that pile dimensions
will be generally controlled by the lateral load demand, we recommend that such drilled foundations
have a diameter of 18 inches or more. Furthermore, to mitigate for the active soil expansion zone, we
recommend that the CIDH piles extend to a depth of 7 feet or more. The pile dimensions
(i.e., diameter and embedment) should be evaluated by the project structural engineer.
The drilled pile construction should be observed by Ninyo & Moore during construction to
evaluate if the piles have been extended to the design depths. It is the contractor's responsibility
to (a) take appropriate measures for maintaining the integrity of the drilled holes, (b) see that the
holes are cleaned and straight, and (c) see that sloughed loose soil is removed from the bottom
of the hole prior to the placement of concrete. Drilled piles should be checked for alignment and
plumbness during installation. The amount of acceptable misalignment of a pile is approximately
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 19
3 inches from the plan location. It is usually acceptable for a pile to be out of plumb by 1 percent
of the depth of the pile. The center-to-center spacing of piles should be no less than three times
the nominal diameter of the pile. If the CIDH piles extend into groundwater or seepage, the
contractor should consider appropriate measures during construction to reduce the potential for
caving of the drilled holes, including the use of steel casing and/or drilling mud. In addition, we
recommend concrete be placed by tremie method, to see that the aggregate and cement do not
segregate during concrete placement, on the same day the CIDH piles are drilled.
For resistance of light pole footings to lateral loads, we recommend an allowable passive
pressure of 300 psf of depth be used with a value of up to 3,000 psf. This value assumes that
the light poles are designed to tolerate ½ inch of deflection at the surface and that the ground is
horizontal for a distance of 10 feet, or three times the height generating the passive pressure,
whichever is greater. We recommend that the upper 1 foot of soil not protected by pavement or
a concrete slab be neglected when calculating passive resistance.
For frictional resistance to lateral loads, we recommend a coefficient of friction of 0.35 be used
between soil and concrete. The passive resistance values may be increased by one-third when
considering loads of short duration such as wind or seismic forces.
10.6 Preliminary Pavement Design
Based on the laboratory test results, we have used an R-value of 5 for the preliminary basis for
design of pavements at the project site. Actual pavement recommendations should be based on
R-value tests performed on bulk samples of the soils that are exposed at the finished subgrade
elevations across the site at the completion of the earthwork operations.
10.6.1 Preliminary Flexible Pavements Design
Our laboratory testing indicated the site soils have an R-value less than 5. Accordingly, we have
used a design R-value of 5 and Traffic Indices (TI) of 5 through 7 for the basis of preliminary
design of flexible pavements for the project. The recommended preliminary flexible pavement
sections for on-site areas presented in Table 4 are designed in accordance with the City of
Carlsbad Engineering Standards (2016). For the preliminary design of flexible pavements we
have used Traffic Indices (TI) of 5, 6, and 7. The preliminary flexible pavement sections are
presented in the following Table 4.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 20
Table 1 – Recommended Preliminary Flexible Pavement Sections
Traffic Index Design
R-Value
Asphalt Concrete
(in)
Class 2
Aggregate Base
(in)
5 5 4 7
6 5 4 12
7 5 4 16
We recommend that the upper 12 inches of the subgrade be compacted to 95 percent of its
Proctor density as evaluated by ASTM D 1557. The aggregate base materials should be
compacted to 95 percent of its Proctor density as evaluated by ASTM D 1557. Additionally,
the AC materials should be compacted to 95 percent of the materials Hveem density. The
above pavement section should provide an approximate pavement life of 20 years. If traffic
loads are different from those assumed, the pavement design should be re-evaluated.
10.6.2 Preliminary Concrete Pavement Design
We suggest that consideration be given to using Portland cement concrete pavements for
the driveway access and storage areas for the fire truck, where dumpsters will be stored,
and where refuse trucks will stop and load. Experience indicates that fire and refuse truck
traffic can significantly shorten the useful life of AC sections. We recommend that in these
areas, 10 inches of 600 psi flexural strength Portland cement concrete reinforced with No. 4
bars, 18-inches on center, be placed over 6 inches or more of aggregate base materials
compacted to a relative compaction of 95 percent.
10.6.3 Exterior Concrete Flatwork
Exterior concrete flatwork should be 4 inches in thickness, be reinforced with No. 3
reinforcing bars placed at 24 inches on-center both ways, and be underlain by subgrade
soils that possess a very low to low potential for expansion (i.e. an expansion index less
than 50). A vapor retarder is not needed for exterior flatwork. To reduce the potential
manifestation of distress to exterior concrete flatwork due to movement of the underlying
soil, we recommend that such flatwork be installed with crack control joints at appropriate
spacing as designed by the structural engineer. Before placement of concrete, the
subgrade soils should be scarified to a depth of 8 inches, moisture conditioned to generally
above the laboratory optimum moisture content, and compacted to a relative compaction of
90 percent as evaluated by ASTM D 1557. Positive drainage should be established and
maintained adjacent to flatwork.
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10.7 Corrosivity
Laboratory testing was performed on a representative sample of the near-surface soil to
evaluate soil pH, electrical resistivity, water-soluble chloride content, and water-soluble sulfate
content. The soil pH and electrical resistivity tests were performed in general accordance with
California Test Method (CT) 643. The chloride content test was performed in general
accordance with CT 422. Sulfate testing was performed in general accordance with CT 417.
The pH of the tested sample was measured at approximately 7.4, the electrical resistivity was
measured at approximately 650 ohm-centimeters, the chloride content was measured at
approximately 190 ppm, and the sulfate content was measured at approximately 0.026 percent
(i.e., 260 ppm). Based on the laboratory test results as compared to the guidelines presented in
American Concrete Institute (ACI) 318 and Caltrans (2015) corrosion criteria, along with our
experience, the project site can be classified as a corrosive site. A corrosive soil site is defined
as a site having earth materials with that possess more than 500 ppm chlorides, more than
0.1 percent sulfates (i.e., 1,000 ppm), a pH of 5.5 or less, and/or an electrical resistivity less
than 1,000 ohm-cm.
10.8 Concrete
Concrete in contact with soil or water that contains high concentrations of soluble sulfates can
be subject to chemical and/or physical deterioration. Based on the CBC criteria (2016) and ACI
318), the potential for sulfate attack is considered negligible for water-soluble sulfate contents in
soil less than 0.1 percent by weight (1,000 ppm). The sample tested during this evaluation
indicated water-soluble sulfate contents of approximately 0.026 percent by weight (i.e., about
260 ppm). Accordingly, the on-site soils are considered to have a negligible potential for sulfate
attack. However, due to the potential variability in soil conditions across the site, we recommend
that Type II, V, or II/V cement be used in concrete in contact with soil.
In order to reduce the potential for shrinkage cracks in the concrete during curing, we
recommend that the concrete be placed with a slump of 4 inches based on ASTM C 143. The
slump should be checked periodically at the site prior to concrete placement. We also
recommend that crack control joints be provided in concrete sidewalks in accordance with the
recommendations of the project structural engineer to reduce the potential for distress due to
minor soil movement and concrete shrinkage. The project structural engineer should be
consulted for additional concrete specifications.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 22
10.9 Drainage
Proper surface drainage is imperative for satisfactory site performance. Positive drainage
should be provided and maintained to direct surface water away from the new sidewalk and
retaining wall improvements. Positive drainage is defined as a slope of 2 percent or more over a
distance of 5 feet away from the foundations and tops of slopes. Runoff should then be directed
by the use of swales or pipes into a collective drainage system. Surface waters should not be
allowed to pond adjacent to footings or pavements.
10.10 Infiltration Devices
Although specifics have not been provided to our office, we anticipate that the project may include
the construction of pervious pavements, bio-retention swales, and/or other infiltration devices. It is
anticipated that lateral movement of water may affect surrounding improvements. Therefore, we
recommend that the site design include the use of pavement edge drains and cutoff curbs along
the sides of infiltration devices to reduce the potential for lateral migration of water. We also
recommend that infiltration devices be set back approximately 20 feet from buildings and the top
of slopes. Gravel backfill should generally be fully wrapped with a non-woven filter fabric (such as
Mirafi 140N), to reduce the potential for fines to migrate to the voids in the gravel.
10.11 Pre-Construction Conference
We recommend that a pre-construction meeting be held prior to commencement of grading. The
owner or his representative, the agency representatives, the architect, the civil engineer,
Ninyo & Moore, and the contractor should attend to discuss the plans, the project, and the
proposed construction schedule.
10.12 Plan Review and Construction Observation
The conclusions and recommendations provided in this report are based on our understanding of
the proposed project and on our evaluation of the data collected based on subsurface conditions
disclosed by widely spaced exploratory borings. If conditions are found to vary from those
described in this report, Ninyo & Moore should be notified, and additional recommendations will
be provided upon request. It is imperative that the interpolated subsurface conditions be checked
by a qualified person during construction. Observation of foundation excavations and observation
and testing of compacted fill and backfill should be performed by a qualified person during
construction. In addition, the project plans and specifications should be reviewed to check for
conformance with the recommendations of this report prior to construction. It should be noted that,
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 23
upon review of these documents, some recommendations presented in this report might be
revised or modified.
During construction we recommend that the duties of the geotechnical consultant include, but
not be limited to:
Observing excavation bottoms and the placement and compaction of fill, including retaining
wall backfill.
Evaluating imported materials prior to their use as fill, if used.
Performing field tests to evaluate fill compaction.
Observing foundation excavations for bearing materials and cleaning prior to placement of
reinforcing steel or concrete.
Ninyo & Moore should perform the needed observation and testing services during construction
operations. In the event that it is decided not to utilize the services of Ninyo & Moore during
construction, we request that the selected consultant provide the client and Ninyo & Moore with a
letter indicating that they fully understand Ninyo & Moore’s recommendations, and that they are in
full agreement with the design parameters and recommendations contained in this report.
Construction of proposed improvements should be performed by qualified subcontractors utilizing
appropriate techniques and construction materials.
11 LIMITATIONS
The field evaluation, laboratory testing, and geotechnical analyses presented in this geotechnical
report have been conducted in general accordance with current practice and the standard of care
exercised by geotechnical consultants performing similar tasks in the project area. No warranty,
expressed or implied, is made regarding the conclusions, recommendations, and opinions presented
in this report. There is no evaluation detailed enough to reveal every subsurface condition. Variations
may exist and conditions not observed or described in this report may be encountered during
construction. Uncertainties relative to subsurface conditions can be reduced through additional
subsurface exploration. Additional subsurface evaluation will be performed upon request.
This document is intended to be used only in its entirety. No portion of the document, by itself, is
designed to completely represent any aspect of the project described herein. Ninyo & Moore
should be contacted if the reader requires additional information or has questions regarding the
content, interpretations presented, or completeness of this document.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 24
This report is intended for design purposes only. It does not provide sufficient data to prepare an
accurate bid by contractors. It is suggested that the bidders and their geotechnical consultant perform
an independent evaluation of the subsurface conditions in the project areas. The independent
evaluations may include, but not be limited to, review of other geotechnical reports prepared for the
adjacent areas, site reconnaissance, and additional exploration and laboratory testing.
Our conclusions, recommendations, and opinions are based on an analysis of the observed site
conditions. If geotechnical conditions different from those described in this report are encountered,
our office should be notified, and additional recommendations, if warranted, will be provided upon
request. It should be understood that the conditions of a site could change with time as a result of
natural processes or the activities of man at the subject site or nearby sites. In addition, changes
to the applicable laws, regulations, codes, and standards of practice may occur due to
government action or the broadening of knowledge. The findings of this report may, therefore, be
invalidated over time, in part or in whole, by changes over which Ninyo & Moore has no control.
This report is intended exclusively for use by the client. Any use or reuse of the findings,
conclusions, and/or recommendations of this report by parties other than the client is undertaken
at said parties’ sole risk.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 25
12 REFERENCES
American Concrete Institute (ACI), 2014, ACI 318 Building Code Requirements for Structural
Concrete and Commentary.
American Society of Civil Engineers (ASCE), 2010, Minimum Design Loads for Buildings and
Other Structures, ASCE 7-10.
Anderson, J.G., Rockwell, T.K., and Agnew, D.C., 1989, Past and Possible Future Earthquakes
of Significance to the San Diego Region: Earthquake Engineering Research Institute
(EERI), Earthquake Spectra, Volume 5, No. 2.
Building News, 2015, “Greenbook”, Standard Specification for Public Works Construction: BNI
Publications.
California Building Standards Commission, 2016, California Building Code (CBC): California
Code of Regulations, Title 24, Part 2, Volumes 1 and 2.
California Department of Conservation, Division of Mines and Geology, 1998, Maps of Known
Active Fault Near-Source Zones in California and Adjacent Portions of Nevada:
International Conference of Building Officials, dated February.
California Department of Transportation (Caltrans), 2015, Corrosion Guidelines (Version 2.1),
Division of Engineering and Testing Services, Corrosion Technology Branch: dated January.
California Department of Transportation (Caltrans), 2016, Highway Design Manual (HDM), 6th
Edition: updated December 16.
California Geological Survey, 1998, Maps of Known Active Fault Near-Source Zones in
California and Adjacent Portions of Nevada.
California Geological Survey, 1999, Seismic Shaking Hazard Maps of California: Map Sheet 48.
California Geological Survey, 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in
California, CGS Special Publication 117A.
California Geological Survey, 2010, Interactive Fault Activity Map of California,
http://maps.conservation.ca.gov/cgs/fam/.
City of Carlsbad, 2016, Engineering Standards, Volume 1: General Design Standards and
Volume 5: Carlsbad BMP Design Manual for Post Construction Treatment BMPs.
County of San Diego Department of Environmental Health, 1991a, Unauthorized Release
#T1666/H24732-001, 1906 Arenal Road, Carlsbad, CA 92009: dated January 22.
County of San Diego Department of Environmental Health, 1991b, Unauthorized Release
#T1666/H24732-001, 1906 Arenal Road, Carlsbad, CA 92009: dated May 13.
Geotracker, 2017, http://geotracker.swrcb.ca.gov/.
Google, Inc., 2017, www.googleearth.com.
Harden, D.R., 2004, California Geology – 2nd ed.: Prentice Hall, Inc.
Hart, E.W., and Bryant, W.A., 1997, Fault-Rupture Hazard Zones in California, Alquist-Priolo
Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps: California
Department of Conservation, Division of Mines and Geology, Special Publication 42, with
Supplements 1 and 2 added in 1999.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017 26
Hartley, J.D., and Duncan, J.M., 1987, E’ and Its Variation with Depth: American Society of Civil
Engineers (ASCE), Journal of Transportation Engineering, Vol. 113, No. 5: dated September.
Historic Aerials, 2017, https://www.historicaerials.com/viewer.
Jennings, C.W. and Bryant, W.A., 2010, Fault Activity Map of California and Adjacent Areas:
California Division of Mines and Geology, California Geologic Data Map Series, Map
No. 6, Scale 1:750,000.
Kennedy, M.P., Tan, S.S., Bovard, K.R., Alvarez, R.M., Watson, M.J., and Gutierrez, C.I., 2007,
Geologic Map of the Oceanside 30’ x 60’ Quadrangle, California.
MV Environmental, 1991a, Sample Collection and Analysis, Former Underground Tank Site at
Fire Station #2, Arenal Road and El Camino Real, Carlsbad, California: dated April 11.
MV Environmental, 1991b, Additional Stockpile Sample Results at Fire Station #2, Arenal Road
and El Camino Real, Carlsbad, California: dated July 30.
MV Environmental, 1991c, Uniform Hazardous Waste Manifest, City of Carlsbad Fire Station #2:
dated September 11.
Ninyo & Moore, 2017, Scope and Fee for Geotechnical Evaluation, Fire Station No. 2, 1906
Arenal Road, Carlsbad, California, Proposal No. P02-00922, dated July 21.
Norris, R.M. and Webb, R.W., 1990, Geology of California: John Wiley & Sons.
SANGIS, 2009, Draft – Liquefaction County of San Diego Hazard Mitigation Planning Map.
Tan and Giffen, 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan
Area, San Diego County, California, Encinitas Quadrangle, Plate D, California Geologic
Survey Landslide Hazard Identification Map No. 35, Open-File Report 95-04.
United States Environmental Protection Agency (EPA) Region 1, 2010, Storm water Best
Management Practices (BMP) Performance Analysis: revised March.
United States Federal Emergency Management Agency (FEMA), 2012, Flood Insurance Rate
Map (FIRM), Map Number 06073C1035G, Panel 1035 of 2375: effective date May 16.
United States Geological Survey, 2015, Encinitas, California Quadrangle Map, 7.5-Minute
Series: Scale 1:24,000.
United States Geological Survey, 2017a, 2008 National Seismic Hazard Maps – Fault Parameters;
http://geohazards.usgs.gov/efusion/hazardfaults_search/hf_search_main.efm.
United States Geological Survey, 2017b, U.S. Seismic Design Maps, Version 3.1.0;
http://earthquake.usgs.gov/hazards/designmaps/usdesign.php.
USDA, Aerial Photograph, Date 1953, Flight AXN-8M, Number 73, Scale 1:20,000: dated April 11.
WLC Architect, 2016, Proposed Site - Option 1 and 2, Carlsbad Fire Station No. 2, Carlsbad,
CA: dated April 29.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
Appendix A
Photographic Documentation
FIGURES
B a t a qu i t osLagoon
5
8
15
805
MAP INDEX
San DiegoCounty
SITE
1_108438001_SL.mxd 10/5/2017 JDLNOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. | SOURCE: ESRI WORLD TOPO, 2017 0 1,500 3,000
FEET
SITE LOCATIONFIGURE 1
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 | 10/17
80
85
ARENAL ROADEL CAMINO REALE
S
T
R
E
L
L
A
D
E
MA
R R
O
A
D
B-1
TD=20.0
IT-1
TD=5.0
B-2
TD=19.8
B-3
TD=20.0
FIRE STATIONNO. 2
2_108438001_BL.mxd 10/12/2017 JDLNOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE.SOURCES: GOOGLE EARTH, 2017 COUNTY OF SAN DIEGO TOPOGRAPHIC SURVEY, 1976.
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 | 10/17
0 50 100
FEET
GEOTECHNICAL MAP
FIGURE 2
BORING
TD=TOTAL DEPTH IN FEET
LEGENDB-3
TD=20.0
INFILTRATION TESTTD=TOTAL DEPTH IN FEETIT-1
TD=5.0
GEOLOGIC CROSS SECTIONAA'
A
A'
APPROXIMATE LOCATIONOF FORMER UST
Qaf
Qoa
FILL
Qaf
TsQaf
Qoa OLD ALLUVIAL FLOODPLAIN
DEPOSITSTsSANTIAGO FORMATION
M E X I C OUSAPacific O c e a n
NEVADA
CALIFORNIA
SAN
JACINTO
ELSINORE
I
M
P
E
RIA
L
WHITTIER
NE
W
PO
RT-INGLEWOOD
C
O
R
O
N
A
D
O
B
A
N
K
S
A
N
D
IE
G
O
T
R
O
U
G
H
SAN
CLEMENTE
S
A
N
T
A
CRUZ-SANTACATALINARIDGE
P
A
L
OS
VERDES
OFFSHORE ZONE
OF DEFORMATION
G ARLOCKCLEARWATERS
A
N
GABRIEL
SIERRAMADRE
BANNING
MISSION CREEK
BLAC
K
W
ATERHARPER
LOCKHART
LEN
W
O
O
D
CAMPROCK
CALIC
O LUDLOW
PIS
GAHBULLION
M
O
U
N
TAIN
JOH
NSO
N
VALLEY
EMERSON
P IN T O M O UN TAINMANIX
MIRAGEVALLEY
NORTHHELENDALE
FRONTAL
CHINO
S A N J O S ECUCAMON G A
MALIBU COAST S A N T A MONICA
SANCAYETANO
SANTASUSANASANTAROSA
N O R T H R ID G E
CHA
RN
O
CK
S A W P ITCAN Y O N
SUPERSTITION
HILLS
R
O
S
E
C
A
NYONPINEMOUNTAIN
W HITEW O LFSAN ANDREAS FAULT ZONEPLEITOWHEELER
POSOCREEK
BLUE CUT
SALTON CR EEK
SAN ANDREAS FAULT ZONECOYOTECREEK
CLARK
GLEN
IVY
EARTHQUAKE
VALLEY ELMORERANCHLAGUNA
SALADA
B
RAWL
EY
S
E
I
S
MI
CZ
ONESan Bernardino County
Kern County
Riverside County
San Diego County
Imperial County
Los Angeles County
Inyo CountyTulare County
Ventura County
Orange County
CAL IFORNIA
HOLOCENE ACTIVE
CALIFORNIA FAULT ACTIVITY
HISTORICALLY ACTIVE
LATE QUATERNARY (POTENTIALLY ACTIVE)STATE/COUNTY BOUNDARY
QUATERNARY (POTENTIALLY ACTIVE)
SOURCE: U.S. GEOLOGICAL SURVEY AND CALIFORNIA GEOLOGICAL SURVEY, 2006,
QUATERNARY FAULT AND FOLD DATABASE FOR THE UNITED STATES.
SITE
3_108438001_FL.mxd 10/5/2017 JDLNOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE.
FAULT LOCATIONS
FIGURE 3
0 30 60
MILES
LEGEND
108438001 | 10/17
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
SITE
4_108438001_G.mxd 10/5/2017 AOBNOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. |SOURCE: GEOLOGY - KENNEDY, M.P., AND TAN, S.S., 2007, GEOLOGIC MAP OF THE OCEANSIDE 30' X 60' QUADRANGLE, CALIFORNIA
GEOLOGY
FIGURE 4
0 2,000 4,000
FEET
108438001 | 10/17
Mzu
Td
LEGEND
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
GEOLOGIC CROSS SECTION A-A'
NOTE: DIMENSIONS, DIRECTIONS AND LOCATIONS ARE APPROXIMATE.0
FEET
FIGURE 5
20 400
5 108438001 CS A-A'.DWGLEGEND
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 I 10/17
80
60
A A'ELEVATION (FEET, MSL)ELEVATION (FEET, MSL)100
80
60
100
40 40
TD=20.0'
B-1
APPROXIMATE FOOTPRINT OFNEW FIRE STATION
B-2
TD=25.0'
BORING
TD=TOTAL DEPTH IN FEET
Qoa OLD ALLUVIAL FLOODPLAIN DEPOSITS
Qaf
N
TD=19.8'
B-2
(PROJECTED 20'
SOUTHWEST)
TD=20.0'
B-3
Qoa
Ts
Qaf FILL
Ts SANTIAGO FORMATION
GEOLOGIC CONTACT,
QUERIED WHERE UNCERTAIN?
??
?
FORMER
UST(PROJECTED20'SOUTHWEST)
NOTES:
GROUNDWATER BELOW BLOCK
GROUNDWATER ABOVE BLOCK2.
1.
P = 170p (D -d )2 2 lb/ft
THRUST
BLOCK
d (VARIES)
P
Pp
p
D (VARIES)
3.ASSUMES BACKFILL IS GRANULAR MATERIAL
4.ASSUMES THRUST BLOCK IS ADJACENT TO COMPETENT MATERIAL
1
Pp2
pP = 2.9 ( D - d )[ 124.8h + 58 ( D+d )]
GROUNDWATER TABLE6.
D, d AND h ARE IN FEET5.
h
lb/ft
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
THRUST BLOCK LATERAL EARTH PRESSURE DIAGRAM
108438001 I 10/17
FIGURE 66 108438001 D-TB.DWG
H+
APPP
D
PASSIVE
PRESSURE
ACTIVE
PRESSURE
DYNAMIC
PRESSURE
RESULTANT
H/3
RESULTANT
D/3
NOTES:
ASSUMES NO HYDROSTATIC PRESSURE BUILD-UP
BEHIND THE RETAINING WALL
1.
2.
BEHIND THE RETAINING WALL
WALL DRAINAGE DETAIL SHOULD BE INSTALLED
DRAINS AS RECOMMENDED IN THE RETAINING3.
BASED ON A PEAK GROUND ACCELERATION OF 0.42g
DYNAMIC LATERAL EARTH PRESSURE IS4.
RECOMMENDED GEOTECHNICAL DESIGN PARAMETERS
Equivalent Fluid Pressure (lb/ft /ft)
Lateral
Earth
Pressure
Level Backfill
with Granular Soils
2 (1)
(2)with Granular Soils
2H:1V Sloping Backfill
(2)
AP
PP
300 D 150 D
EP
42 H 69 H
Level Ground 2H:1V Descending Ground
18 H
H AND D ARE IN FEET7.
SETBACK SHOULD BE IN ACCORDANCE WITH8.
THE CBC
RETAINING
WALL
SURCHARGE PRESSURES CAUSED BY VEHICLES6.
OR NEARBY STRUCTURES ARE NOT INCLUDED
EP
RESULTANT
H/3
P IS CALCULATED IN ACCORDANCE WITH THE5.
RECOMMENDATIONS OF MONONOBE AND MATSUO
(1929), AND ATIK AND SITAR (2010).
E
LATERAL EARTH PRESSURES FOR YIELDING RETAINING WALLS
FIGURE 77 108438001 D-YRW.DWGFIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 I 10/17
GRANULAR BACKFILL MATERIALS SHOULD BE
USED FOR RETAINING WALL BACKFILL
H+
oPPP
D
PASSIVE
PRESSURE
AT-REST
PRESSURE
DYNAMIC
PRESSURE
H/3
RESULTANT
D/3
RECOMMENDED GEOTECHNICAL DESIGN PARAMETERS
Equivalent Fluid Pressure (lb/ft /ft)
Lateral
Earth
Pressure
Level Backfill
with Granular Soils
2 (1)
(2)with Granular Soils
2H:1V Sloping Backfill(2)
OP
PP
300 D 150 D
EP
62 H 90 H
Level Ground 2H:1V Descending Ground
18 H
SLAB RESULTANT
RETAINING
WALL
EP
H/3
RESULTANT
NOTES:
ASSUMES NO HYDROSTATIC PRESSURE BUILD-UP
BEHIND THE RETAINING WALL
1.
2.
BEHIND THE RETAINING WALL
WALL DRAINAGE DETAIL SHOULD BE INSTALLED
DRAINS AS RECOMMENDED IN THE RETAINING3.
BASED ON A PEAK GROUND ACCELERATION OF 0.42g
DYNAMIC LATERAL EARTH PRESSURE IS4.
H AND D ARE IN FEET7.
SURCHARGE PRESSURES CAUSED BY VEHICLES6.
OR NEARBY STRUCTURES ARE NOT INCLUDED
P IS CALCULATED IN ACCORDANCE WITH THE5.
RECOMMENDATIONS OF MONONOBE AND MATSUO
(1929), AND ATIK AND SITAR (2010).
E
LATERAL EARTH PRESSURES FOR RESTRAINED RETAINING WALLS
FIGURE 88 108438001 D-RRW.DWGGRANULAR BACKFILL MATERIALS SHOULD BE
USED FOR RETAINING WALL BACKFILL
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 I 10/17
SOIL BACKFILL COMPACTED TO 90%
RELATIVE COMPACTION *
OUTLET
4-INCH-DIAMETER PERFORATED
SCHEDULE 40 PVC PIPE OR EQUIVALENT
INSTALLED WITH PERFORATIONS DOWN;
1% GRADIENT OR MORE TO A SUITABLE
3/4-INCH OPEN-GRADED GRAVEL WRAPPED
IN AN APPROVED GEOFABRIC.
3 INCHES
WALL FOOTING
FINISHED GRADE
RETAINING WALL
12 INCHES
12 INCHES
VARIESGEOFABRIC
*BASED ON ASTM D1557
RETAINING WALL DRAINAGE DETAIL
FIGURE 99 108438001 D-RW.DWGFIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 I 10/17
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
APPENDIX A
Boring Logs
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
APPENDIX A
BORING LOGS
Field Procedure for the Collection of Disturbed Samples
Disturbed soil samples were obtained in the field using the following method.
Bulk Samples
Bulk samples of representative earth materials were obtained from the exploratory borings.
The samples were bagged and transported to the laboratory for testing.
Field Procedure for the Collection of Relatively Undisturbed Samples
Relatively undisturbed soil samples were obtained in the field using the following method.
The Modified Split-Barrel Drive Sampler
The sampler, with an external diameter of 3 inches, was lined with 1-inch-long, thin brass rings
with inside diameters of approximately 2.4 inches. The sample barrel was driven into the
ground with the weight of a hammer in general accordance with ASTM D 3550-01. The driving
weight was permitted to fall freely. The approximate length of the fall, the weight of the hammer,
and the number of blows per foot of driving are presented on the boring logs as an index to the
relative resistance of the materials sampled. The samples were removed from the sample
barrel in the brass rings, sealed, and transported to the laboratory for testing.
Soil Classification Chart Per ASTM D 2488
Primary Divisions Secondary Divisions
Group Symbol Group Name
COARSE-
GRAINED
SOILS
more than
50% retained
on No. 200
sieve
GRAVEL more than 50% of coarse fraction
retained on No. 4 sieve
CLEAN GRAVEL
less than 5% fines
GW well-graded GRAVEL
GP poorly graded GRAVEL
GRAVEL with DUAL CLASSIFICATIONS 5% to 12% fines
GW-GM well-graded GRAVEL with silt
GP-GM poorly graded GRAVEL with silt
GW-GC well-graded GRAVEL with clay
GP-GC poorly graded GRAVEL with
GRAVEL with FINES more than
12% fines
GM silty GRAVEL
GC clayey GRAVEL
GC-GM silty, clayey GRAVEL
SAND 50% or more of coarse fraction passes No. 4 sieve
CLEAN SAND less than 5% fines
SW well-graded SAND
SP poorly graded SAND
SAND with DUAL CLASSIFICATIONS 5% to 12% fines
SW-SM well-graded SAND with silt
SP-SM poorly graded SAND with silt
SW-SC well-graded SAND with clay
SP-SC poorly graded SAND with clay
SAND with FINES more than 12% fines
SM silty SAND
SC clayey SAND
SC-SM silty, clayey SAND
FINE-
GRAINED
SOILS
50% or
more passes
No. 200 sieve
SILT and CLAY
liquid limit less than 50%
INORGANIC
CL lean CLAY
ML SILT
CL-ML silty CLAY
ORGANIC OL (PI > 4)organic CLAY
OL (PI < 4)organic SILT
SILT and CLAY liquid limit 50% or more
INORGANIC CH fat CLAY
MH elastic SILT
ORGANIC
OH (plots on or above “A”-line)organic CLAY
OH (plots below “A”-line)organic SILT
Highly Organic Soils PT Peat
USCS METHOD OF SOIL CLASSIFICATION
Apparent Density - Coarse-Grained Soil
Apparent Density
Spooling Cable or Cathead Automatic Trip Hammer
SPT (blows/foot)
Modified Split Barrel (blows/foot)
SPT (blows/foot)
Modified Split Barrel (blows/foot)
Very Loose < 4 < 8 < 3 < 5
Loose 5 - 10 9 - 21 4 - 7 6 - 14
Medium
Dense 11 - 30 22 - 63 8 - 20 15 - 42
Dense 31 - 50 64 - 105 21 - 33 43 - 70
Very Dense > 50 > 105 > 33 > 70
Consistency - Fine-Grained Soil
Consis-tency
Spooling Cable or Cathead Automatic Trip Hammer
SPT (blows/foot)
Modified Split Barrel (blows/foot)
SPT (blows/foot)
Modified Split Barrel (blows/foot)
Very Soft < 2 < 3 < 1 < 2
Soft 2 - 4 3 - 5 1 - 3 2 - 3
Firm 5 - 8 6 - 10 4 - 5 4 - 6
Stiff 9 - 15 11 - 20 6 - 10 7 - 13
Very Stiff 16 - 30 21 - 39 11 - 20 14 - 26
Hard > 30 > 39 > 20 > 26
LIQUID LIMIT (LL), %PLASTICITY INDEX (PI), %0 10
107
4
20
30
40
50
60
70
0 20 30 40 50 60 70 80 90 100
MH or OH
ML or OLCL - ML
Plasticity Chart
Grain Size
Description Sieve Size Grain Size Approximate Size
Boulders > 12”> 12”Larger than basketball-sized
Cobbles 3 - 12”3 - 12”Fist-sized to basketball-sized
Gravel
Coarse 3/4 - 3”3/4 - 3”Thumb-sized to fist-sized
Fine #4 - 3/4”0.19 - 0.75”Pea-sized to thumb-sized
Sand
Coarse #10 - #4 0.079 - 0.19”Rock-salt-sized to
pea-sized
Medium #40 - #10 0.017 - 0.079”Sugar-sized to rock-salt-sized
Fine #200 - #40 0.0029 - 0.017”Flour-sized to sugar-sized
Fines Passing #200 < 0.0029”Flour-sized and smaller
CH or OH
CL or OL
0
5
10
15
20
XX/XX
SM
CL
Bulk sample.
Modified split-barrel drive sampler.
No recovery with modified split-barrel drive sampler.
Sample retained by others.
Standard Penetration Test (SPT).
No recovery with a SPT.
Shelby tube sample. Distance pushed in inches/length of sample recovered in inches.
No recovery with Shelby tube sampler.
Continuous Push Sample.
Seepage.
Groundwater encountered during drilling.
Groundwater measured after drilling.
MAJOR MATERIAL TYPE (SOIL):
Solid line denotes unit change.
Dashed line denotes material change.
Attitudes: Strike/Dipb: Bedding
c: Contactj: Joint
f: FractureF: Fault
cs: Clay Seams: Shear
bss: Basal Slide Surfacesf: Shear Fracture
sz: Shear Zonesbs: Shear Bedding Surface
The total depth line is a solid line that is drawn at the bottom of the boring.
BORING LOG
Explanation of Boring Log Symbols
PROJECT NO.DATE FIGUREDEPTH (feet)BulkSAMPLESDrivenBLOWS/FOOTMOISTURE (%)DRY DENSITY (PCF)SYMBOLCLASSIFICATIONU.S.C.S.BORING LOG EXPLANATION SHEET
Updated Nov. 2011
BORING LOG
20
0
10
20
30
40
CL FILL:Brown to reddish brown, moist, stiff, sandy CLAY; scattered roots and chunks of
concrete.
Total Depth = 5 feet.
Groundwater not encountered during drilling.
Boring converted to infiltration test shortly after drilling on 8/30/17.
Backfilled on 8/31/17.
Note: Groundwater, though not encountered at the time of drilling, may rise to a
higher level due to seasonal variations in precipitation and several other factors
as discussed in the report.
The ground elevation shown above is an estimation only. It is based on our
interpretations of published maps and other documents reviewed for the purposes
of this evaluation. It is not sufficiently accurate for preparing construction bids and
design documents.
FIGURE A- 1
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 |10/17DEPTH (feet)BulkSAMPLESDrivenBLOWS/FOOTMOISTURE (%)DRY DENSITY (PCF)SYMBOLCLASSIFICATIONU.S.C.S.DESCRIPTION/INTERPRETATION
DATE DRILLED 8/30/17 BORING NO.IT-1
GROUND ELEVATION 86' (MSL)SHEET 1 OF
METHOD OF DRILLING Manual
DRIVE WEIGHT N/A DROP N/A
SAMPLED BY GSW LOGGED BY GSW REVIEWED BY CAT
1
0
10
20
30
40
50/2"
50/4"
84
53
6.8
11.4
119.0
118.4
SM
SM
FILL:Brown, moist, medium dense, silty fine to medium SAND; scattered roots up to
approximately 3 inches in diameter.
OLD ALLUVIUM:Brown, dry to moist, medium dense, silty fine SAND.
SANTIAGO FORMATION:Reddish brown and gray mottled, moist, moderately cemented, clayey fine-
grained SANDSTONE; weathered.
Brown, moist, moderately cemented, silty fine-grained SANDSTONE.
Trace clay; scattered black manganese deposits.
Light brown, moist, moderately cemented, clayey fine- to medium-grained
SANDSTONE; micaceous; some iron-oxide staining.
Yellowish brown, moist, moderately cemented, silty fine-grained SANDSTONE.
Light grayish brown; weakly cemented.
Total Depth = 20 feet.
Groundwater not encountered during drilling.
Backfilled shortly after drilling on 8/30/17.
Note: Groundwater, though not encountered at the time of drilling, may rise to a
higher level due to seasonal variations in precipitation and several other factors
as discussed in the report.
The ground elevation shown above is an estimation only. It is based on our
interpretations of published maps and other documents reviewed for the purposes
of this evaluation. It is not sufficiently accurate for preparing construction bids and
design documents.
FIGURE A- 2
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 |10/17DEPTH (feet)BulkSAMPLESDrivenBLOWS/FOOTMOISTURE (%)DRY DENSITY (PCF)SYMBOLCLASSIFICATIONU.S.C.S.DESCRIPTION/INTERPRETATION
DATE DRILLED 8/30/17 BORING NO.B-1
GROUND ELEVATION 88' (MSL)SHEET 1 OF
METHOD OF DRILLING 8" Diameter Hollow Stem Auger (CME-75) (Baja)
DRIVE WEIGHT 140 lbs. (Auto-Trip)DROP 30"
SAMPLED BY CAT LOGGED BY CAT REVIEWED BY CAT
1
0
10
20
30
40
56
79
94/10"
91/9"
9.5
13.6
135.1
114.9
SM
SC
ASPHALT CONCRETE:Approximately 4 inches thick underlain by approximately 8 inches of base.
FILL:Brown, moist, medium dense, silty fine to coarse SAND; trace clay; scattered
gravel up to 2 inches in diameter.Light brown and dark brown (mottled), moist, medium dense, clayey fine to
medium SAND; scattered shells and shell fragments.
SANTIAGO FORMATION:Brown, moist, moderately cemented, silty fine-grained SANDSTONE.
Brown and grayish brown (mottled); moderately to strongly cemented; trace clay.
Light brown and grayish brown (mottled), moist, strongly cemented, clayey fine-
grained SANDSTONE.
Light brown; weakly to moderately cemented; fine- to medium-grained.
Total Depth = 19.8 feet.
Groundwater not encountered during drilling.
Backfilled and patched with black dyed concrete shortly after drilling on 8/30/17.
Note: Groundwater, though not encountered at the time of drilling, may rise to a
higher level due to seasonal variations in precipitation and several other factors
as discussed in the report.
The ground elevation shown above is an estimation only. It is based on our
interpretations of published maps and other documents reviewed for the purposes
of this evaluation. It is not sufficiently accurate for preparing construction bids and
design documents.
FIGURE A- 3
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 |10/17DEPTH (feet)BulkSAMPLESDrivenBLOWS/FOOTMOISTURE (%)DRY DENSITY (PCF)SYMBOLCLASSIFICATIONU.S.C.S.DESCRIPTION/INTERPRETATION
DATE DRILLED 8/30/17 BORING NO.B-2
GROUND ELEVATION 89' (MSL)SHEET 1 OF
METHOD OF DRILLING 8" Diameter Hollow Stem Auger (CME-75) (Baja)
DRIVE WEIGHT 140 lbs. (Auto-Trip)DROP 30"
SAMPLED BY CAT LOGGED BY CAT REVIEWED BY CAT
1
0
10
20
30
40
24
50/6"
89/11"
68
15.7
17.3
111.0
110.8
SC
CL
PORTLAND CEMENT CONCRETE:Approximately 9-1/4 to 10 inches thick; rebar at approximately 6-1/4 to 6-1/2
inches thick below top of concrete; underlain by approximately 6 to 8 inches thick
of sandy base material.
FILL:Brown, moist, medium dense, clayey fine to medium SAND; scattered gravel up
to approximately 2 inches in diameter.Few sandy zones; scattered seashell fragments.Dark brown and light brown (mottled).
Dark brown, moist, stiff to firm, fine to medium sandy CLAY.
SANTIAGO FORMATION:Grayish brown and light brown (mottled), moist, moderately to strongly cemented,
silty fine-grained SANDSTONE; scattered pockets of clayey sandstone.
Yellowish brown; moderately cemented; massive.
Brown, moist, moderately cemented, clayey fine- to medium-grained
SANDSTONE; scattered caliche.Total Depth = 20 feet.
Groundwater not encountered during drilling.
Backfilled and patched with concrete shortly after drilling on 8/30/17.
Note: Groundwater, though not encountered at the time of drilling, may rise to a
higher level due to seasonal variations in precipitation and several other factors
as discussed in the report.
The ground elevation shown above is an estimation only. It is based on our
interpretations of published maps and other documents reviewed for the purposes
of this evaluation. It is not sufficiently accurate for preparing construction bids and
design documents.
FIGURE A- 4
FIRE STATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
108438001 |10/17DEPTH (feet)BulkSAMPLESDrivenBLOWS/FOOTMOISTURE (%)DRY DENSITY (PCF)SYMBOLCLASSIFICATIONU.S.C.S.DESCRIPTION/INTERPRETATION
DATE DRILLED 8/30/17 BORING NO.B-3
GROUND ELEVATION 87' (MSL)SHEET 1 OF
METHOD OF DRILLING 8" Diameter Hollow Stem Auger (CME-75) (Baja)
DRIVE WEIGHT 140 lbs. (Auto-Trip)DROP 30"
SAMPLED BY CAT LOGGED BY CAT REVIEWED BY CAT
1
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
APPENDIX B
Laboratory Testing
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
APPENDIX B
LABORATORY TESTING
Classification
Soils were visually and texturally classified in accordance with the Unified Soil Classification
System (USCS) in general accordance with ASTM D 2488-00. Soil classifications are indicated
on the logs of the exploratory borings in Appendix A.
In-Place Moisture and Density Tests
The moisture content and dry density of relatively undisturbed samples obtained from the
exploratory borings were evaluated in general accordance with ASTM D 2937-04. The test
results are presented on the logs of the exploratory borings in Appendix A.
Gradation Analysis
A gradation analysis test was performed on a selected representative soil sample in general
accordance with ASTM D 422. The grain-size distribution curve is shown on Figure B-1. These
test results were utilized in evaluating the soil classifications in accordance with the USCS.
Direct Shear Tests
A direct shear test was performed on a relatively undisturbed sample in general accordance with
ASTM D 3080 to evaluate the shear strength characteristics of the selected material. The
sample was inundated during shearing to represent adverse field conditions. The results are
shown on Figure B-2.
Expansion Index Tests
The expansion indices of selected materials were evaluated in general accordance with ASTM
D 4829. The specimens were molded under a specified compactive energy at approximately
50 percent saturation. The prepared 1-inch thick by 4-inch diameter specimens were loaded
with a surcharge of 144 psf and were inundated with tap water. Readings of volumetric swell
were made for a period of 24 hours. The results of the tests are presented on Figure B-3.
R-Value
The resistance value, or R-value, for site soils was evaluated in general accordance with CT
301. The sample was prepared and evaluated for exudation pressure and expansion pressure.
The equilibrium R-value is reported as the lesser or more conservative of the two calculated
results. The test results are shown on Figure B-4.
Soil Corrosivity Tests
Soil pH and electrical resistivity tests were performed on a representative sample in general
accordance with CT 643. The sulfate and chloride contents of the selected sample were
evaluated in general accordance with CT 417 and 422, respectively. The test results are shown
on Figure B-5.
PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 2844/CT 301
LESS THAN 5Clayey Sand (SC)1.5-4.0B-3
SAMPLE LOCATION SAMPLE DEPTH
(ft)SOIL TYPE R-VALUE
R-VALUE TEST RESULTS
FIRESTATION NO. 2
1906 ARENAL ROAD, CARLSBAD, CALIFORNIA
1084348001 | 10/17
FIGURE B-5
108438001_RVTABLE1.xlsx
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
APPENDIX C
Infiltration Testing
Test Date:Infiltration Test No.: IT-1
Test Hole Diameter, D (inches): 6.0 Excavation Depth (feet): 5.0
Test performed and recorded by: GSW Pipe Length (feet): 5.0
(min/in) (in/hr)
7:40 4.00 8:05 4.13 25 0.13 16 0.94 0.44
8:05 4.00 8:30 4.11 25 0.11 19 0.95 0.37
8:30 4.00 9:00 4.11 30 0.11 23 0.95 0.31
9:00 4.00 9:30 4.11 30 0.11 23 0.95 0.31
9:30 4.00 10:00 4.10 30 0.10 25 0.95 0.28
10:00 4.00 10:30 4.10 30 0.10 25 0.95 0.28
10:30 4.00 11:00 4.10 30 0.10 25 0.95 0.28
11:00 4.00 11:30 4.10 30 0.10 25 0.95 0.28
11:30 4.00 12:00 4.10 30 0.10 25 0.95 0.28
12:00 4.00 12:30 4.10 30 0.10 25 0.95 0.28
12:30 4.00 1:00 4.10 30 0.10 25 0.95 0.28
1:00 4.00 1:30 4.10 30 0.10 25 0.95 0.28
Notes:
t1 = initial time when filling or refilling is completed
d1 = initial depth to water in hole at t1
t2 = final time when incremental water level reading is taken
d2 = final depth to water in hole at t2
∆t = change in time between initial and final water level readings
∆H = change in depth to water or change in height of water column (i.e., d2 - d1)It = tested infiltration rate, inches/hour
H0 = Initial height of water column ∆H = change in head over the time interval, inches
in/hr = inches per hour ∆t = time interval, minutes
r = effective radius of test hole
Havg = average head over the time interval, inches
Percolation Rate to Infiltration Rate Conversion1
1 Based on the "Porchet Method" as presented in:
Riverside County Flood Control, 2011, Design Handbook for Low Impact
Development Best Management Practices: dated September.
Infiltration Rate∆H
(feet)
Percolation
Rate Havg
(feet)
8/31/2017
t1
d1
(feet)t2
d2
(feet)
∆t
(min)
ܫ௧ ൌ ∆ܪ ൈ 60 ൈ ݎ
∆ݐ ݎ2ܪ௩
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 Appendix C | October 13, 2017 1 of 1
Appendix I: Forms and Checklists
I-3 February 2016
Categorization of Infiltration Feasibility
Condition
Form I-8
Part 1 - Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any undesirable
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
1
Is the estimated reliable infiltration rate below proposed
facility locations greater than 0.5 inches per hour? The response
to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2 and Appendix
D.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
2
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of geotechnical hazards (slope stability,
groundwater mounding, utilities, or other factors) that cannot
be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.2.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Appendix I: Forms and Checklists
I-4 February 2016
Form I-8 Page 2 of 4
Criteri
a Screening Question Yes No
3
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of groundwater contamination (shallow
water table, storm water pollutants or other factors) that cannot
be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.3.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
4
Can infiltration greater than 0.5 inches per hour be allowed
without causing potential water balance issues such as change
of seasonality of ephemeral streams or increased discharge of
contaminated groundwater to surface waters? The response to
this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.3.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Part 1
Result
*
If all answers to rows 1 - 4 are “Yes” a full infiltration design is potentially feasible.
The feasibility screening category is Full Infiltration
If any answer from row 1-4 is “No”, infiltration may be possible to some extent but
would not generally be feasible or desirable to achieve a “full infiltration” design.
Proceed to Part 2
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings.
Appendix I: Forms and Checklists
I-5 February 2016
Form I-8 Page 3 of 4
Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
5
Do soil and geologic conditions allow for infiltration in any
appreciable rate or volume? The response to this Screening
Question shall be based on a comprehensive evaluation of the
factors presented in Appendix C.2 and Appendix D.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
6
Can Infiltration in any appreciable quantity be allowed
without increasing risk of geotechnical hazards (slope
stability, groundwater mounding, utilities, or other factors)
that cannot be mitigated to an acceptable level? The response
to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Appendix I: Forms and Checklists
I-6 February 2016
Form I-8 Page 4 of 4
Criteria Screening Question Yes No
7
Can Infiltration in any appreciable quantity be allowed
without posing significant risk for groundwater related
concerns (shallow water table, storm water pollutants or other
factors)? The response to this Screening Question shall be based
on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
8
Can infiltration be allowed without violating downstream
water rights? The response to this Screening Question shall be
based on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis:
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Part 2
Result*
If all answers from row 5-8 are yes then partial infiltration design is potentially feasible.
The feasibility screening category is Partial Infiltration.
If any answer from row 5-8 is no, then infiltration of any volume is considered to be
infeasible within the drainage area. The feasibility screening category is No Infiltration.
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings.
Ninyo & Moore | Fire Station No. 2, 1906 Arenal Road, Carlsbad, California | 108438001 | October 18, 2017
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