HomeMy WebLinkAboutCT 2019-0003; CARLSBAD STATION; PRELIMINARY GEOTECHNICAL EVALUATION; 2021-03-16 ADVANCED GEOTECHNICAL SOLUTIONS, INC.
485 Corporate Drive, Suite B
Escondido, California 92029
Telephone: (619) 867-0487 Fax: (714) 409-3287
ORANGE AND L.A. COUNTIES INLAND EMPIRE SAN DIEGO AND IMPERIAL COUNTIES
(714) 786-5661 (619) 867-0487 (619) 850-3980
McKellar McGowan March 16, 2021
888 Prospect St. #330 P/W 1809-04
La Jolla CA 92037 Report No. 1809-04-B-7
Attention: Mr. Scott A. Myers
Subject: Preliminary Geotechnical Evaluation, Carlsbad Station, 2747-2801 Roosevelt Street,
2802 State Street, Carlsbad, California
References: See Appendix A
Gentlepersons:
Pursuant to your request, presented herein is Advanced Geotechnical Solutions, Inc.’s, (AGS) preliminary
geotechnical evaluation report for the proposed Carlsbad Station project in the city of Carlsbad, California.
The purpose of this geotechnical evaluation is to assess the site geologic and geotechnical conditions and
provide conclusions and recommendations for the construction of the proposed mixed-use development
and associated improvements.
Advanced Geotechnical Solutions, Inc., appreciates the opportunity to provide you with geotechnical
consulting services and professional opinions. If you have any questions, please contact the undersigned at
(619) 867-0487.
Respectfully Submitted,
Advanced Geotechnical Solutions, Inc.
_______________________________ _______________________________
ANDRES BERNAL, Sr. Geotechnical Engineer PAUL J. DERISI
RCE 62366, RGE 2715, Reg. Exp. 9-30-21 CEG 2536, Reg. Exp. 5-31-21
Distribution: (1) Addressee
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TABLE OF CONTENTS
1.0 INTRODUCTION .............................................................................................................. 1
1.1. Background and Purpose ................................................................................................ 1
1.2. Scope of Study ................................................................................................................ 1
1.3. Geotechnical Study Limitations ...................................................................................... 1
2.0 SITE LOCATION AND DESCRIPTION .......................................................................... 2
2.1. Site Location and Description ......................................................................................... 2
2.2. Proposed Development ................................................................................................... 2
3.0 FIELD AND LABORATORY INVESTIGATION ........................................................... 2
4.0 ENGINEERING GEOLOGY ............................................................................................. 3
4.1. Regional Geologic and Geomorphic Setting .................................................................. 3
4.2. Site Geology.................................................................................................................... 3
4.2.1. Topsoil .................................................................................................................... 3
4.2.2. Artificial Fill ........................................................................................................... 3
4.2.3. Quaternary Old Paralic Deposits, Units 6-7 (Map Symbol Qop6-7)........................ 3
4.2.4. Tertiary-aged Santiago Formation (Map Symbol Tsa) ........................................... 3
4.3. Groundwater ................................................................................................................... 4
4.4. Seismic Hazards .............................................................................................................. 4
4.4.1. Surface Fault Rupture ............................................................................................. 4
4.4.2. Liquefaction ............................................................................................................ 4
4.4.3. Dynamic Settlement ................................................................................................ 4
4.4.4. Lateral Spreading .................................................................................................... 5
4.4.5. Seismically Induced Landsliding ............................................................................ 5
4.4.6. Earthquake Induced Flooding ................................................................................. 5
4.5. Seismic Design Parameters ............................................................................................. 5
5.0 GEOTECHNICAL ENGINEERING.................................................................................. 6
5.1. Material Properties .......................................................................................................... 6
5.1.1. Excavation Characteristics ...................................................................................... 6
5.1.2. Compressibility ....................................................................................................... 6
5.1.3. Expansion Potential ................................................................................................ 6
5.2. Analytical Methods ......................................................................................................... 7
6.0 CONCLUSIONS AND RECOMMENDATIONS ............................................................. 7
6.1. Earthwork ........................................................................................................................ 7
6.1.1. Site Preparation ....................................................................................................... 7
6.1.2. Removals................................................................................................................. 7
6.1.3. Materials for Fill ..................................................................................................... 7
6.1.4. Import Soils ............................................................................................................. 8
6.1.5. Compacted Fill ........................................................................................................ 8
6.1.6. Mixing and Moisture Control ................................................................................. 8
6.1.7. Utility Trench Backfill ............................................................................................ 8
6.1.8. Flatwork Subgrade Preparation............................................................................... 8
6.2. Excavations and Shoring................................................................................................. 9
6.2.1. Monitoring of Settlement and Lateral Movement ................................................ 10
6.2.2. Construction Dewatering ...................................................................................... 10
6.2.3. Excavation Bottom Stability ................................................................................. 11
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6.3. Foundation Design Recommendations ......................................................................... 11
6.3.1. Shallow Foundations ............................................................................................. 11
6.3.2. Mat Foundation ..................................................................................................... 11
6.3.3. Foundation Excavations ........................................................................................ 12
6.3.4. Isolated Footings ................................................................................................... 12
6.4. Retaining Wall Design .................................................................................................. 12
6.4.1. Lateral Earth Pressures ......................................................................................... 12
6.4.2. Seismic Earth Pressure .......................................................................................... 13
6.4.3. Permanent Retaining Walls and Waterproofing ................................................... 13
6.5. Exterior Flatwork .......................................................................................................... 13
6.6. Site Drainage ................................................................................................................. 13
6.7. Corrosion....................................................................................................................... 14
6.8. Concrete Mix Design .................................................................................................... 14
6.9. Buried Metallic Materials ............................................................................................. 14
7.0 FUTURE STUDY NEEDS ............................................................................................... 15
7.1. Plan Review .................................................................................................................. 15
7.2. Observation during Construction .................................................................................. 15
8.0 CLOSURE ........................................................................................................................ 15
ATTACHMENTS:
Figure 1 - Site Location Map
Figure 2 - Exploration Location Map
Figure 3 - Regional Geologic Map
Appendix A - References
Appendix B - Subsurface Exploration
Appendix C - Laboratory Test Results
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PRELIMINARY GEOTECHNICAL EVALUATION
CARLSBAD STATION
2747-2801 ROOSEVELT STREET, 2802 STATE STREET
CITY OF CARLSBAD, CALIFORNIA
1.0 INTRODUCTION
1.1. Background and Purpose
Advanced Geotechnical Solutions, Inc., (AGS) has prepared this report that presents the results of
our geotechnical investigation onsite and provides preliminary recommendations for the design and
construction of the proposed mixed-use Carlsbad Station project in the city of Carlsbad, California.
1.2. Scope of Study
The scope of our study included the following tasks:
➢ Reviewing pertinent published and unpublished geologic and geotechnical literature, maps, and
aerial photographs readily available to this firm (Appendix A, References).
➢ Review of subsurface exploration performed by AGS (2019b) at the site. Boring logs are
presented in Appendix B.
➢ Preparing a map showing the locations of exploratory borings utilizing the civil engineering
plans prepared by BHA, Inc. as a base;
➢ Review of laboratory testing performed by AGS (2019b) on soil samples collected at the site.
Laboratory results are presented in Appendix C.
➢ Provide seismic site classification and design parameters in accordance with 2019 CBC;
➢ Discussion of seismic hazards including faulting, liquefaction, and mitigation, if needed;
➢ Discussion on groundwater conditions and the potential effects on the proposed construction;
➢ Recommendations for dewatering;
➢ Preparation of shoring design recommendations;
➢ Preliminary design recommendations for foundations, retaining walls, pavement, and flatwork
construction;
➢ Discussion of onsite soil corrosivity; and,
➢ Preparing this geotechnical evaluation report with associated exhibits summarizing our
findings. This report is suitable for preliminary design and regulatory review.
1.3. Geotechnical Study Limitations
The conclusions and recommendations in this report are professional opinions based on the data
developed during our subsurface investigation and information provided in the referenced
geotechnical reports prepared by others. The conclusions presented herein are based upon the
current design as reflected on the included project development plans. Changes to the plan would
necessitate further review.
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The materials immediately adjacent to or beneath those observed may have different characteristics
than those observed. No representations are made as to the quality or extent of materials not
observed. Any evaluation regarding the presence or absence of hazardous materials is beyond the
scope of this firm's services.
2.0 SITE LOCATION AND DESCRIPTION
2.1. Site Location and Description
The “L” shaped 1.7-acre site (see Figure 1, Site Location Map) is bounded by Roosevelt Street to
the northeast; commercial and residential buildings to the north, south and west and extends
southwesterly to State Street. Currently, the site supports several one- to two-story commercial
buildings constructed in the 1950’s to 1980’s (?) along with several driveways and at-grade parking.
According to our review of site topographic plans, elevations range from a high of 46 feet above
mean sea level (msl) at the eastern corner to a low of 40 ft. msl at the northwest corner.
2.2. Proposed Development
Based on our review of civil engineering plans prepared by BHA, Inc. dated May 15, 2020, and
architectural plans by Robert Hidey Architects dated April 28, 2020, it is our understanding that
the development will include a concrete “podium” subterranean parking level extending to El. 30.7
msl with two four-story buildings above. The at-grade level will include retail/restaurant space
along the street areas with the interior space and upper three stories for residential units. At this
time, structural plans are not available for our review. However, according to our conversation with
the project structural engineer, it is anticipated that the subterranean parking garage will be
supported by a mat slab foundation system and the four-story buildings will have structural steel
and wood frame construction.
3.0 FIELD AND LABORATORY INVESTIGATION
On March 18, 2019, AGS performed a subsurface investigation at the site which consisted of advancing
three 8-inch diameter hollow stem auger borings labeled B-1 through B-3 using a truck-mounted drill rig to
approximate depths ranging between 31 feet and 35 feet below existing ground surface (bgs).
On May 23, 2019, three percolation test boreholes labeled P-1 through P-3 were manually excavated at the
project site to approximate depths of 3 to 5 feet bgs. Percolation testing was performed to evaluate the
feasibility of storm water infiltration at the site and provide preliminary infiltration rates for BMP design
(AGS, 2019a). The borings were logged and sampled by a representative of AGS. Logs of the borings are
presented in Appendix B. The approximate locations of the borings are shown on Figure 2, Exploration
Location Map.
Undisturbed and bulk samples from the borings were transported to AGS’ laboratory and tested for in-situ
density and moisture content, direct shear strength, consolidation, expansion index, and
resistivity/corrosion potential. Laboratory test results are presented in Appendix C and on the boring logs.
FIGURE
1
DATE:
2/21
SITE LOCATION MAP
PROJECT NO.:
1809-04
NOTE: ALL DIMENSIONS, DIRECTIONS AND LOCATIONS ARE APPROXIMATE.SOURCE: USGS, SAN LUIS REY QUADRANGLE, 2018.
CARLSBAD STATION
STATE STREET AND ROOSEVELT STREET
CARLSBAD, CALIFORNIA
N
BuenaVista Lagoon
SITE
SCALE 1”= 1,000’
DATE:3/21PROJECT NO.:1809-04NOTE: ALL DIMENSIONS, DIRECTIONS AND LOCATIONS ARE APPROXIMATE.FIGURE :2CARLSBAD STATIONSTATE STREET AND ROOSEVELT STREET CARLSBAD, CALIFORNIAEXPLORATION LOCATION MAPSOURCE: bHA, Inc. 2019, GARAGE DESIGN PLAN SHEET.LEGENDAPPROXIMATE BORING LOCATION TD = TERMINATION DEPTH IN FEET P-1TD=3' B-3TD=31'APPROXIMATE INFILTRATION TEST LOCATION TD = TERMINATION DEPTH IN FEET P-3TD=5'ROOSEVELT STREETP-2TD=4'P-3TD=5'B-1TD=35' B-2TD=31' B-3TD=31' SCALE 1”= 40’
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4.0 ENGINEERING GEOLOGY
Our discussion of the geologic conditions at the site is based on our field exploration and review of available
geologic literature. Our findings regarding regional and local geology, including faulting and seismicity,
landslides, and groundwater conditions at the subject site are provided in the following sections.
4.1. Regional Geologic and Geomorphic Setting
The subject site is situated within the Peninsular Ranges Geomorphic Province. The Peninsular
Ranges geomorphic province occupies the southwestern portion of California and extends
southward to the southern tip of Baja California. In general, the province consists of steeply sloped,
northwest trending mountain ranges composed of metamorphosed Late Jurassic to Early
Cretaceous-age extrusive volcanic rock and Cretaceous-age plutonic rock of the Peninsular Ranges
Batholith. The westernmost portion of the province is predominantly underlain by younger marine
and non-marine sedimentary rocks. The dominant structural feature is northwest-southeast trending
crustal blocks bounded by active faults of the San Andreas transform system.
4.2. Site Geology
The regional geologic map (Figure 3) indicates that the geologic units onsite consist of Quaternary-
age Old Paralic Deposits underlain by Tertiary-age Santiago Formation (Kennedy, M.P., and Tan,
S.S., 2005). The following is a brief description of the geologic units encountered.
4.2.1. Topsoil
A shallow layer of topsoil is present in the landscape areas throughout the site. These soils
consist of dark brown to dark reddish brown, slightly moist to moist, silty sand to sand in
a loose condition with gravel and abundant roots extending to 4 to 6 inches depth.
4.2.2. Artificial Fill
Artificial fill was encountered under topsoil. The artificial fill consists of grayish brown to
dark brown, slightly moist to moist, silty sand to sand in a loose to medium dense condition.
Artificial fill thickness ranges from approximately 1.0 to 3.0 feet with potential localized
deeper areas. Documentation regarding fill placement was not available for our review.
4.2.3. Quaternary Old Paralic Deposits, Units 6-7 (Map Symbol Qop6-7)
Quaternary-age Old Paralic Deposits were encountered at the surface and underlying
artificial fill onsite. These soils generally consist of reddish to grey brown and olive, moist
to saturated, medium dense to very dense, silty to clayey, fine- to medium-grained sand.
The Old Paralic Deposits extend to variable depths ranging between 20 and 25 feet bgs.
This unit is massive with portions prone to caving and is considered suitable for support of
fills and anticipated structural loads.
4.2.4. Tertiary-aged Santiago Formation (Map Symbol Tsa)
Santiago Formation materials underlie the site at depth and generally consist of light brown
to light gray, moist to wet, very dense, silty sand with trace clay.
FIGURE
3
DATE
2/21
PROJECT NO.
1809-04
REGIONAL GEOLOGIC MAP
NOTE: ALL DIMENSIONS, DIRECTIONS AND LOCATIONS ARE APPROXIMATE.
CARLSBAD STATION
STATE STREET AND ROOSEVELT STREET
CARLSBAD, CALIFORNIA
LEGEND
ARTIFICIAL FILL
MARINE BEACH DEPOSITS
OLD PARALIC DEPOSITS, UNITS 2-4
OLD PARALIC DEPOSITS, UNITS 6-7
SANTIAGO FORMATION
TONALITE UNDIVIDED
N
Tsa
SOURCE: GEOLOGIC MAP OF THE OCEANSIDE 30’ X 60’ QUADRANGLE, 2005.
SITE
Qa
Qls
Kt
Qvop12
SCALE 1”= 2,000’
Qop2-4
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4.3. Groundwater
Groundwater was encountered in borings B-1 through B-3 at variable depths ranging between 9
feet and 13½ feet which correspond approximately to El. 32 ft. msl. According to our review of
previous geotechnical studies in the site vicinity (AGS, 2019c), we estimate that the historical high
groundwater level at the project site is at El. 35 ft. msl. Localized perched groundwater may develop
at a later date, most likely at or near fill/bedrock contacts, due to fluctuations in precipitation,
irrigation practices, or factors not evident at the time of our field explorations.
4.4. Seismic Hazards
The site is located in the tectonically active Southern California area, and will therefore likely
experience shaking effects from earthquakes. The type and severity of seismic hazards affecting
the site are to a large degree dependent upon the distance to the causative fault, the intensity of the
seismic event, the direction of propagation of the seismic wave and the underlying soil
characteristics. Seismic hazards may be primary, such as surface rupture and/or ground shaking, or
secondary, such as liquefaction, seismically induced slope failure or dynamic settlement. The
following is a site-specific discussion of ground motion parameters, earthquake-induced landslide
hazards, settlement, and liquefaction.
4.4.1. Surface Fault Rupture
The project site is not located within an Alquist-Priolo Earthquake Fault Zone. 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 area is considered significant during
the design life of the proposed structure. The nearest known active fault corresponds to the
offshore Rose Canyon fault system located approximately 4.4 miles west of the site. This
system has the potential to be the dominant source of strong ground motion. The potential
for fault surface rupture on the subject site is low. However, lurching or cracking of the
ground surface as a result of nearby seismic events is possible.
4.4.2. Liquefaction
Liquefaction is the phenomenon in which loosely deposited granular soils with silt and clay
contents of less than approximately 35 percent and non-plastic silts located below the water
table undergo rapid loss of shear strength when subjected to strong earthquake-induced
ground shaking. Ground shaking of sufficient duration results in the loss of grain-to-grain
contact due to a rapid rise in pore water pressure and causes the soil to behave as a fluid
for a short period of time. Based on the proposed excavation of loose artificial fill and
dense old paralic deposits for construction of the underground parking level, the
liquefaction potential of the site will be mitigated to a negligible level.
4.4.3. Dynamic Settlement
Seismic settlement can occur when loose to medium-dense granular materials densify
during seismic shaking and liquefaction. Seismically-induced settlement may occur in dry,
unsaturated, as well as saturated soils. Based on the proposed basement excavation and
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dense materials encountered below the basement level, the potential for dynamic settlement
at the site is negligible.
4.4.4. Lateral Spreading
Liquefaction-induced lateral spreading is defined as the finite, lateral displacement of
gently sloping ground as a result of pore pressure build-up or liquefaction in a shallow
underlying deposit during an earthquake. Due to the presence of dense underlying
formational materials, the potential for lateral spreading is considered to be very low.
4.4.5. Seismically Induced Landsliding
Landslides are deep-seated ground failures in which a crown-shaped section of a slope
separates and slides downhill. The project site is relatively level and does not have any
slopes greater than five feet in height. Review of aerial photos and topographic maps, as
well as field observations during geologic mapping and subsurface exploration activities,
indicates no evidence of deep-seated landsliding in the vicinity of the project.
4.4.6. Earthquake Induced Flooding
Earthquake induced flooding can be caused by tsunamis, dam failures, or seiches.
According to our review of the Tsunami Inundation Map for the Oceanside Quadrangle
(CGS, 2009), the site is not located within the tsunami inundation area. A seiche is a free
or standing-wave oscillation on the surface of water in an enclosed or semi-enclosed basin
initiated by an earthquake. Based on the absence of enclosed basins near the site, the risk
of seismically induced flooding due to seiche or dam failure is very low.
4.5. Seismic Design Parameters
After implementation of the recommendations provided in this report, the site may be classified as
Seismic Site Class D consisting of a stiff soil profile with average SPT N blowcount between 15
and 50 blows per foot. Table 4.5 presents seismic design parameters in accordance with 2019 CBC
and mapped spectral acceleration parameters (United States Geological Survey, 2020). Site
coordinates of Latitude 33.1616°N and Longitude 117.3503°W were utilized.
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TABLE 4.5
2019 CBC SEISMIC DESIGN PARAMETERS
Seismic Site Class D
Mapped Spectral Acceleration Parameter at Period of 0.2-Second, Ss 1.082g
Mapped Spectral Acceleration Parameter at Period 1-Second, S1 0.391g
Site Coefficient, Fa 1.067
Site Coefficient, Fv N/A3
Adjusted MCER1 Spectral Response Acceleration Parameter at Short Period, SMS 1.155g
1-Second Period Adjusted MCER1 Spectral Response Acceleration Parameter, SM1 N/A3
Short Period Design Spectral Response Acceleration Parameter, SDS 0.770g
1-Second Period Design Spectral Response Acceleration Parameter, SD1 N/A3
Peak Ground Acceleration, PGAM2 0.536g
Seismic Design Category N/A3
Notes: 1 Risk-Targeted Maximum Considered Earthquake
2 Peak Ground Acceleration adjusted for site effects
3 Requires Site Specific Ground Motion Hazard Analysis per ASCE 7-16 Section 11.4.8
As indicated in Note 3 above, ASCE 7-16 Section 11.4.8 requires a site specific ground motion
hazard analysis unless, per Exception 2, the value of the seismic response coefficient, CS, is
determined by Equation (12.8-2) for values of T 1.5TS and taken as equal to 1.5 times the values
computed with either Equation (12.8-3) for TL ≥ T > 1.5TS or Equation (12.8-4) for T > TL.
5.0 GEOTECHNICAL ENGINEERING
Presented herein is a general discussion of the geotechnical properties of the various soil types and the
analytic methods used in this report.
5.1. Material Properties
5.1.1. Excavation Characteristics
Our evaluation of the excavation characteristics of the onsite materials is based on the
results of the exploratory borings and our experience with similar materials. It is anticipated
that excavations within topsoil, artificial fill and Old Paralic Deposits can be accomplished
with heavy-duty earthmoving equipment in good working condition. Although not
anticipated, excavations into Santiago Formation materials may encounter cemented zones
which would require heavy ripping.
5.1.2. Compressibility
Onsite materials that are significantly compressible include topsoil and artificial fill. Based
on the proposed excavation depth, these materials will be completely removed during
basement excavation.
5.1.3. Expansion Potential
Expansive soils are characterized by their ability to undergo significant volume changes
(shrink or swell) due to variations in moisture content. Based on our laboratory testing, it
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is anticipated that the expansion potential of the onsite materials will be “Very Low”.
Although not anticipated, mitigation measures for expansive soils are provided in the
recommendations section of this report.
5.2. Analytical Methods
Ultimate bearing capacity and shoring design values were obtained using the graphs and formulas
presented in NAVFAC DM-7.1. Allowable bearing was determined by applying a factor of safety
of at least three to the ultimate bearing capacity.
Static lateral earth pressures were calculated using Rankine methods for active and passive cases.
If it is desired to use Coulomb forces, a separate analysis specific to the application can be
conducted.
6.0 CONCLUSIONS AND RECOMMENDATIONS
Construction of the proposed development is considered feasible from a geotechnical standpoint provided
the conclusions and recommendations presented herein are incorporated into the design and construction
of the project.
6.1. Earthwork
Earthwork should be accomplished under the observation and testing of the project soils engineer
and engineering geologist or their authorized representative in accordance with our
recommendations, project specifications, and requirements of the applicable governing agencies.
6.1.1. Site Preparation
Site preparation should begin with the removal of vegetation, utility lines, asphalt,
concrete, and other deleterious debris from areas to be graded. Clearing and grubbing
should extend outside of the proposed excavation and fill areas. 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. Abandoned utilities
should be removed and/or backfilled with slurry in accordance with local regulations.
6.1.2. Removals
Topsoil and artificial fill are not considered suitable for structural support in their present
condition and will be removed during basement excavations to approximate depths ranging
between 10 and 17 feet anticipated onsite.
The majority of the excavated soils may be reused for engineered fills provided they are
clean of debris and organic content. The extent and depth of removals should be evaluated
by the soil engineer or engineering geologist in the field based on the materials exposed.
6.1.3. Materials for Fill
Onsite soils with an organic content of less than approximately 3 percent by volume (or 1
percent by weight) are suitable for use as fill. In general, fill materials should not contain
rocks or lumps over approximately 3 inches in diameter, and not more than approximately
40 percent larger than ¾-inch. Utility trench backfill material should not contain rocks or
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lumps over approximately 3 to 4 inches in general. Soils classified as silts or clays should
not be used for backfill in the pipe zone. Larger chunks, if generated during excavation,
may be broken into acceptably sized pieces or disposed of offsite.
6.1.4. Import Soils
Import soils, if required, should consist of clean, structural quality, compactable materials
and should be free of trash, debris or other objectionable materials. At least three working
days should be allowed in order for the geotechnical consultant to sample, test and approve
the potential import material.
6.1.5. Compacted Fill
Prior to placement of compacted fill, the contractor should request an evaluation of the ex-
posed ground surface by AGS. Unless otherwise recommended, the exposed ground sur-
face 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 at least 90 percent of the maximum dry
density as determined by ASTM D1557. Fill should be placed in thin (6 to 8-inch) lifts,
moisture conditioned to optimum moisture or slightly above, and compacted to a minimum
of 90 percent relative compaction until the desired grade is achieved.
6.1.6. Mixing and Moisture Control
In order to prevent layering of different soil types and/or different moisture contents,
mixing and moisture control of materials will be necessary. The preparation of the earth
materials through mixing and moisture control should be accomplished prior to and as part
of the compaction of each fill lift.
6.1.7. Utility Trench Backfill
Utility trench backfill should be compacted to at least 90 percent relative compaction.
Onsite soils will not be suitable for use as bedding material but will be suitable for use in
backfill. No surcharge loads should be imposed above excavations. This includes spoil
piles, lumber, concrete trucks or other construction materials and equipment.
Drainage above excavations should be directed away from the banks. Care should be taken
to avoid saturation of the soils. Compaction should be accomplished by mechanical means.
Jetting of native soils will not be acceptable.
6.1.8. Flatwork Subgrade Preparation
The upper one foot of subgrade soil below exterior slabs, sidewalks, driveways, patios, etc.
should be compacted to minimum 90 percent relative compaction. The subgrade below
exterior slabs, sidewalks, driveways, patios, etc. should be moisture conditioned to
optimum moisture content prior to concrete placement.
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6.2. Excavations and Shoring
Excavations and utility trenches should be laid back in accordance with applicable Cal-OSHA
standards. Based on our observations, onsite soils may be classified as Cal-OSHA soil type “C”.
Any temporary excavation greater than 5 feet in height should be laid back with a 1.5:1
(horizontal:vertical) gradient.
For vertical excavations less than approximately 15 feet in height, cantilevered shoring may be
used. A triangular distribution of lateral earth pressure based on an equivalent fluid pressure of 38
pcf is recommended for design of cantilevered shoring. It is assumed that the backfill soils are
drained and that a level surface exists behind the cantilevered shoring. Significant lateral
displacement and vertical settlement may occur behind cantilever shoring.
If tied-back or braced shoring is used, a trapezoidal distribution of lateral earth pressure is
recommended for shoring design. The recommended pressure distribution, for the case where the
grade is level behind the shoring, is illustrated in the following diagram with the maximum pressure
equal to 25H in psf, where H is the height of the shored wall in feet.
O.2H
0.2H
0.6H H = Height of Shored Wall (feet)
25H (psf)
For design of tie-backs, a friction angle of 35 degrees, a cohesion of 200 psf and an average
frictional resistance of 1,000 psf can be used for the portion of anchor embedded in old paralic
deposits. Only the frictional resistance developed beyond the active wedge will be effective in
resisting lateral loads. It can be assumed that the active wedge adjacent to the shoring wall is defined
by a plane drawn at 35 degrees from vertical through the bottom of the excavation. Anchor
capacities should be proof-tested during construction. Where satisfactory tests are not achieved, the
anchor diameter and/or length should be increased until satisfactory test results are obtained.
Continuous lagging will be required throughout. The soldier piles and tie-back anchors should be
designed for the full-anticipated lateral pressure; however, the pressure on the lagging will be less
due to arching in the soils. For design of lagging, the earth pressure can be limited to a maximum
value of 400 psf. All lumber left in the ground should be treated in accordance with Section 204-2
of the “Standard Specifications for Public Works Construction”.
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Any surcharge (live loads, including traffic, or dead loads) located within a 1:1 plane drawn upward
and outward from the base of the shored excavation, including adjacent structures, should be added
to the lateral earth pressures. The lateral contribution of a uniform surcharge load located
immediately behind the temporary shoring can be estimated as approximately 35% of the
magnitude of the vertical surcharge pressure for the “active” and “at-rest” conditions, respectively.
As a minimum, a 300 psf vertical uniform surcharge is recommended to account for the neighboring
structures and/or traffic loads. Additional lateral load contributions for surcharges located behind
the shored wall may be provided once the load configuration and layout are known.
6.2.1. Monitoring of Settlement and Lateral Movement
We anticipate that settlement of the ground surface may occur behind the shoring wall
during and after excavations. The amount of settlement depends heavily on the type of
shoring system, the contractor’s workmanship, and soil conditions. structures and
improvements in the vicinity of the planned shoring installation should be reviewed with
regard to foundation support and tolerance to settlement. To reduce the potential for
distress to adjacent structures, we recommend that the shoring system be designed to limit
ground settlement behind the shoring system to 1/2 inch or less. The shoring system should
be design by an experienced shoring engineer. The shoring parameters presented in this
report should be considered as guidelines.
We recommend an array of ground survey points be installed to monitor settlement. The
survey points should be installed on the shoring system and incrementally away from the
excavation. The contractor should be responsible for maintaining the total settlement
beneath adjacent buildings to less than 1/2 inch. If settlements reach ¼ inch, we recommend
that a review of the contractor’s methods be performed, and appropriate changes be made,
if needed.
Consideration should be given to placing survey monitoring points on nearby structures to
monitor the performance of the structures. In this way, a record of the performance of the
structure will be maintained and available. This information, in conjunction with pre-
construction surveys, is helpful in reducing potential claims and expediting and limiting
settlement of legitimate claims.
6.2.2. Construction Dewatering
Excavations should not be made within 2 feet of the groundwater level. Based on the
proposed excavation depth, construction dewatering will be necessary to excavate footings
for the basement level. The dewatering system should be designed by an experienced
engineer allowing for the groundwater level to be monitored during construction.
Considerations for construction dewatering should include anticipated drawdown, volume
of pumping, potential for settlement, and groundwater discharge. Disposal of groundwater
should be performed in accordance with guidelines of the Regional Water Quality Control
Board.
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ADVANCED GEOTECHNICAL SOLUTIONS, INC.
6.2.3. Excavation Bottom Stability
If a suitable dewatering system is in place, we anticipate that the bottom of the excavation
will be stable and should provide appropriate support to the proposed building. Care should
be taken not to disturb the excavation bottom during construction activities. The use of
heavy or vibratory equipment at the bottom of the excavation is not recommended since it
may disturb the subgrade. Excavations near the water table may be stabilized by placing
gravel or rock up to 8-inch maximum size along the base of the seepage zone. Any loose,
soft or deleterious material should be removed prior to placement of gravel or rock. The
construction of a mud slab may also provide a stable working platform during construction.
Recommendations for stabilizing excavation bottoms should be based on evaluation in the
field by the geotechnical consultant at the time of construction.
6.3. Foundation Design Recommendations
Detailed foundation plans are not currently available; however, it is our understanding that the
underground parking level will be supported by a conventional shallow foundation system or a mat
foundation placed on competent formational materials.
6.3.1. Shallow Foundations
For design of shallow foundations supported on competent formation, the values presented
in Table 6.3.1 should be used.
TABLE 6.3.1
SHALLOW FOUNDATION DESIGN PARAMETERS
Minimum Footing
Dimensions1 24 inches in width and 24 inches in depth.
Allowable Bearing
Capacity
3,000 pounds per square foot (psf). May be increased by 500 psf
for each additional foot of foundation width and depth,
respectively, up to a maximum of 4,000 psf.
Allowable bearing values may be increased by one-third for
transient live loads from wind or seismic forces.
Estimated Static
Settlement
Total settlement: 1.0 inch
Differential settlement: 0.5 inch over 40 feet.
Static settlement of the foundation system is expected to occur
on initial application of loading.
Friction Coefficient 0.40 (Soil/Concrete)
Lateral Bearing2 400 psf/foot of depth to a maximum of 4,000 psf (Level Condition)
Notes: 1. Depth of footing embedment should be measured below lowest adjacent finish grade.
2. For resisting lateral forces on footings, lateral bearing and sliding coefficient may be
combined with a maximum sliding resistance limited to ½ of dead load.
6.3.2. Mat Foundation
Mat foundations should be designed by the structural engineer in conformance with the
2019 California Building Code. The allowable bearing pressure is an average value applied
to the total area of the mat foundation and was used to evaluate the overall static settlement
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ADVANCED GEOTECHNICAL SOLUTIONS, INC.
of the foundation. In our model, the mat foundation was assumed to be rigid with respect
to the soil. The recommended geotechnical design parameters are presented in Table 6.3.2.
TABLE 6.3.2
RIGID MAT FOUNDATION DESIGN PARAMETERS
Average Allowable
Bearing Capacity
2,000 psf
Allowable bearing values may be increased by one-third for
transient live loads from wind or seismic forces.
Estimated Static
Settlement
Total settlement: 0.5 inch
Differential settlement (tilt): 0.25 inch over 40 feet.
Static settlement of the foundation system is expected to
occur on initial application of loading.
Mat foundations typically experience some deflection due to loads placed on the mat and
the reaction of the soils underlying the mat. For the approximate flexible design of slab-
on-grade mat foundation systems a modulus of subgrade reaction (Kv1) of 200 pci is
recommended. The modulus of subgrade reaction is based on a unit square foot area and
should be adjusted for the planned mat size. The coefficient of subgrade reaction Kb for a
mat of a specific width, may be evaluated using the following equation:
Kb = Kv1[(b+1)/2b]2
where b is the width of the foundation.
6.3.3. Foundation Excavations
Foundation excavations should be observed by the geotechnical consultant. Footings
should be excavated into competent formation materials. The excavations should be free
of loose and sloughed materials, be neatly trimmed, and moisture conditioned at the time
of concrete placement. Footing excavations should not be allowed to dry back and should
be kept moist until concrete is poured.
6.3.4. Isolated Footings
Isolated footings outside the structure footprint should be tied with grade beams to the
structure in two orthogonal directions.
6.4. Retaining Wall Design
6.4.1. Lateral Earth Pressures
Restrained walls (non-yielding) may be designed for an at-rest pressure represented by an
equivalent fluid weight of 64 pcf. Due to the anticipated “bathtub” condition, the basement
wall design should consider the hydrostatic pressure generated by groundwater at El. 35
feet msl. Retaining walls should also be designed for any surcharge loading located within
a 1:1 plane drawn upward and outward from the base of the wall, including adjacent
structures as described in Section 6.2.
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6.4.2. Seismic Earth Pressure
In addition to the above static pressures, unrestrained retaining walls with more than 6 feet
of backfill height should be designed to resist seismic loading as required by 2016 CBC.
The seismic load can be modeled as a thrust load applied at a point 0.6H above the base of
the wall, where H is equal to the height of the wall. The seismic load (in pounds per lineal
foot of wall) may be calculated as follows:
Pe = ⅜ *γ*H2 *kh
where: Pe = Seismic thrust load
H = Height of the wall (feet)
γ = soil unit weight = 125 pounds per cubic foot (pcf)
kh = seismic pseudostatic coefficient = 0.5 * PGAM (PGAM=0.536g)
6.4.3. Permanent Retaining Walls and Waterproofing
Permanent retaining walls will be required for the subterranean basement level. It is
anticipated that the retaining walls for the basement level will be formed against the
temporary shoring. After permanent bracing such as floor slabs have been installed, the
tieback anchors used for the shoring (if any) should be detensioned and documented by the
geotechnical engineer. The basement slab and walls should be waterproofed with a
HDPE/Bentonite sheet membrane dual waterproofing system such as Tremco Paraseal®
or similar material that can be used in post-installation submerged conditions, and under
the slab where hydrostatic water head exists. Slab penetrations below the groundwater
should be avoided where possible. If necessary, slab penetrations should be designed and
detailed for groundwater conditions. A waterproofing specialist should be consulted to
provide detailed recommendations.
6.5. Exterior Flatwork
Concrete flatwork should be designed utilizing 4-inch minimum thickness. Consideration should
be given to construct a thickened edge (scoop footing) at the perimeter of slabs and walkways
adjacent to landscape areas to minimize moisture variation below these improvements. The
thickened edge (scoop footing) should extend approximately 8 inches below concrete slabs and
should be a minimum of 6 inches wide.
Weakened plane joints should be installed on walkways at intervals of approximately 6 to 8 feet.
Exterior slabs should be designed to withstand shrinkage of the concrete. Consideration should be
given to reinforcing any exterior flatwork.
6.6. Site Drainage
Roof, pad, and slope drainage should be diverted away from slopes and structures to suitable
discharge areas by non-erodible devices (e.g., gutters, downspouts, concrete swales, etc.). Positive
drainage adjacent to structures should be established and maintained. Positive drainage may be
accomplished by providing drainage away from the structure at a gradient of 2 percent or steeper
for a distance of 5 feet outside the building perimeter, and further maintained by a graded swale
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ADVANCED GEOTECHNICAL SOLUTIONS, INC.
leading to an appropriate outlet, in accordance with the recommendations of the project civil
engineer and/or landscape architect.
Surface drainage on the site should be provided so that water is not permitted to pond. A gradient
of 2 percent or steeper should be maintained over the pad area and drainage patterns should be
established to divert and remove water from the site to appropriate outlets. Drainage patterns
established at the time of grading should be maintained for the life of the project.
6.7. Corrosion
Laboratory testing was performed on a representative sample of the onsite earth materials to
evaluate pH and electrical resistivity, as well as chloride and sulfate contents. The pH and electrical
resistivity tests were performed in accordance with California Test (CT) 643 and the sulfate and
chloride content tests were performed in accordance with CT 417 and CT 422, respectively. These
laboratory test results are presented in Appendix C.
The results of corrosivity testing indicated an electrical resistivity value of 1,000 ohm-cm, soil pH
value of 7.5, chloride content of 141 parts per million (ppm) and sulfate content of 0.015 percent
(i.e., 148 ppm). Based on Caltrans (2018) corrosion criteria, onsite soils would not be classified as
corrosive, which is defined as soils with more than 500 ppm chlorides, more than 0.2 percent
sulfates, or a pH less than 5.5. We recommend that the corrosivity of site soils be further evaluated
by a corrosion engineer.
6.8. Concrete Mix Design
Concrete in contact with soil or water that contains high concentrations of soluble sulfates can be
subject to chemical deterioration. Laboratory testing indicated a sulfate content of 0.015 percent
for the tested sample, which corresponds to sulfate exposure Class S0 (sulfate content below 0.1%)
per ACI 318 (2014). Although the sulfate content test results were not significantly high, due to the
variability in the onsite soils and the potential future use of reclaimed water at the site, we
recommend that Type II/V cement be used for concrete structures in contact with soil.
6.9. Buried Metallic Materials
The onsite soils are expected to be corrosive to buried metallic materials. AGS recommends
minimally that the current standard of care be employed for protection of metallic construction
materials in contact with onsite soils or that consultation with an engineer specializing in corrosion
to determine specifications for protection of construction materials.
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7.0 FUTURE STUDY NEEDS
7.1. Plan Review
Once shoring and foundation plans become available, they should be reviewed by AGS to verify
that the design recommendations presented are consistent with the proposed construction.
7.2. Observation during Construction
Geologic exposures afforded during grading operations provide the best opportunity to evaluate the
anticipated site geologic structure. Continuous geologic and geotechnical observations, testing, and
mapping should be provided throughout site development.
Additional near-surface samples should be collected by the geotechnical consultant during grading
and subjected to laboratory testing. Final design recommendations should be provided in a grading
report based on the observation and test results collected during grading.
8.0 CLOSURE
The findings and recommendations in this report are based on the specific excavations, observations, and
tests results as noted herein. The findings are based on the review of the field and laboratory data combined
with an interpolation and extrapolation of conditions between and beyond the exploratory excavations. The
results reflect an interpretation of the direct evidence obtained. Services performed by AGS have been
conducted in a manner consistent with that level of care and skill ordinarily exercised by members of the
profession currently practicing in the same locality under similar conditions. No other representation, either
expressed or implied, and no warranty or guarantee is included or intended.
The recommendations presented in this report are based on the assumption that an appropriate level of field
review will be provided by geotechnical engineers and engineering geologists who are familiar with the
design and site geologic conditions. That field review shall be sufficient to confirm that geotechnical and
geologic conditions exposed during grading are consistent with the geologic representations and
corresponding recommendations presented in this report. If the project description varies from what is
described in this report, AGS must be consulted regarding the applicability of, and the necessity for, any
revisions to the recommendations presented herein. AGS should review structural plans to verify whether
the recommendations presented herein are incorporated into the design. AGS accepts no liability for any
use of its recommendations if the project description or final design varies and AGS is not consulted
regarding the changes.
The data, opinions, and recommendations of this report are applicable to the specific design of this project
as discussed in this report. They have no applicability to any other project or to any other location, and any
and all subsequent users accept any and all liability resulting from any use or reuse of the data, opinions,
and recommendations without the prior written consent of AGS.
AGS has no responsibility for construction means, methods, techniques, sequences, or procedures, or for
safety precautions or programs in connection with the construction, for the acts or omissions of the
CONTRACTOR, or any other person performing any of the construction, or for failure of any of them to
carry out the construction in accordance with the final design drawings and specifications.
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
APPENDIX A
REFERENCES
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ADVANCED GEOTECHNICAL SOLUTIONS, INC.
APPENDIX A
REFERENCES
Advanced Geotechnical Solutions, 2019a, Preliminary Infiltration Feasibility Study for Carlsbad Station,
Roosevelt Street and State Street, Carlsbad, California, dated June 4, 2019, Report No. 1809-04-B-
5R.
---, 2019b, Preliminary Geotechnical Feasibility Investigation, Carlsbad Station, Carlsbad, California, dated
April 25, 2019, Report No. 1809-04-B-4R.
---,.2019c, Geotechnical Due Diligence Evaluation, Antique Block (Carlsbad Village 80 LLC), Carlsbad,
California, dated February 25, 2019, Report No. 1809-04-B-2.
California Building Standards Commission, 2019, 2019 California Building Code, Title 24, Part 2, Volumes
1 and 2.
California Department of Conservation, 2010, 2010 Fault Activity Map of California.
California Division of Mines and Geology (CDMG), 2008, Guidelines for Evaluating and Mitigating
Seismic Hazards in California, Special Publication 117A.
California Geological Survey, 2009, Tsunami Inundation Map for Emergency Planning, Oceanside
Quadrangle/San Luis Rey Quadrangle, dated June 1, 2009.
California Water Boards, Geotracker web site, 2021, Depth to Groundwater,
http://geotracker.waterboards.ca.gov/gama/gamamap/public/default.asp
FEMA, 2019, Flood Insurance Rate Map, San Diego County, Map Numbers 06073C0761H, Revised
December 20, 2019, Scale: 1”=500’.
Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas: California Geological Survey,
California Geologic Data Map No. 6, Scale 1:750,000.
Kennedy, M.P., and Tan, S.S., 2005, Geologic Map of the Oceanside 30’ x 60’ Quadrangle, California
Regional Geologic Map Series, Scale 1:100,000. California Building Standards Commission
(2019). California Building Code.
United States Geologic Survey (USGS), 2021, Unified Hazard Tool,
https://earthquake.usgs.gov/hazards/interactive/
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
APPENDIX B
SUBSURFACE EXPLORATION
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ADVANCED GEOTECHNICAL SOLUTIONS, INC.
APPENDIX B
SUBSURFACE EXPLORATION
Field Procedure for the Collection of Disturbed Samples
Disturbed soil samples were obtained in the field using the following methods.
Bulk Samples
Bulk samples of representative earth materials were obtained from the exploratory boring. The
samples were bagged and transported to the laboratory for testing.
The Standard Penetration Test (SPT) Sampler
Disturbed drive samples of earth materials were obtained by means of a Standard Penetration Test
sampler. The sampler is composed of a split barrel with an external diameter of 2 inches and an
unlined internal diameter of 1-3/8 inches. The sampler was driven into the ground 12 to 18 inches
with a 140-pound hammer free-falling from a height of 30 inches in general accordance with
ASTM D 1586. The blow counts were recorded for every 6 inches of penetration; the blow counts
reported on the logs are those for the last 12 inches of penetration. Soil samples were observed
and removed from the sampler, bagged, sealed 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 3.0 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 140-pound hammer, in general accordance with ASTM D 3550. 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.
.
OLD PARALIC DEPOSITS (Qop)
Silty SAND, fine-grained, reddish brown, moist, mediumdense.
@ 4 ft. grades to yellowish brown.
@ 5 ft. grades to yellowish gray, mottled red, very dense,iron oxide.
@ 10 ft. same, trace clay.
@ 15 ft. grades to yellowish gray, saturated. Groundwater.
@ 20 ft. grades to light reddish gray.
14-26-48(74)
4-10-33(43)
16-23-29
(52)
6-50/5"
BU
MC
MC
MC
MC
130
116
120
6.3
13.4
11.2
61
83
77
SM
CONS
CORR
NOTES
GROUND ELEVATION 42 ft
LOGGED BY AB
DRILLING METHOD Hollow Stem Auger
HOLE SIZE 8
DRILLING CONTRACTOR Baja Exploration GROUND WATER LEVELS:
CHECKED BY PJD
DATE STARTED 3/18/19 COMPLETED 3/18/19
AT TIME OF DRILLING 15.00 ft / Elev 27.00 ft
AT END OF DRILLING 11.00 ft / Elev 31.00 ft
AFTER DRILLING ---
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)0
5
10
15
20
25 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
(Continued Next Page)PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 1 OF 2
BORING NUMBER B-1
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:49 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 BORING LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
SANTIAGO FORMATION (Tsa)
Silty SAND, fine-grained, light gray to light grayish brown,moist, very dense.
@ 30 ft. same, trace clay.
@ 35 ft. same.
Total Depth = 35.3 ft.Groundwater encountered during drilling at 15 feet;groundwater measured at completion of drilling at 11 feet.
No caving.Backfilled in accordance with SDCDEH requirements.
50/4"
50
50/4"
MC
MC
MC
118
123
122
8.6
10.6
7.8
SM
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)25
30
35 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 2 OF 2
BORING NUMBER B-1
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:49 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 BORING LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
ASPHALTIC CONCRETE 2 inches AC on native.
OLD PARALIC DEPOSITS (Qop)Silty SAND, fine-grained, reddish brown, moist, mediumdense.
@ 5 ft. grades to yellowish gray, mottled red and black, verydense, iron oxide.
@ 8 ft. grades to light reddish gray, damp.
@ 10 ft. grades to yellowish gray, moist, medium dense.
@ 15 ft. grades to light grayish brown, saturated.Groundwater.
SANTIAGO FORMATION (Tsa)
Silty SAND, fine- to medium-grained, light grayish brown,wet, very dense, trace clay.
25-30-41(71)
7-13-15(28)
14-29-50
(79)
36-50/3"
BU
MC
SPT
MC
SPT
112 13.9 77
SM
SM
DS
NOTES
GROUND ELEVATION 45 ft
LOGGED BY AB
DRILLING METHOD Hollow Stem Auger
HOLE SIZE 8
DRILLING CONTRACTOR Baja Exploration GROUND WATER LEVELS:
CHECKED BY PJD
DATE STARTED 3/18/19 COMPLETED 3/18/19
AT TIME OF DRILLING 15.00 ft / Elev 30.00 ft
AT END OF DRILLING 13.50 ft / Elev 31.50 ft
AFTER DRILLING ---
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)0
5
10
15
20
25 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
(Continued Next Page)PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 1 OF 2
BORING NUMBER B-2
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:49 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 BORING LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
SANTIAGO FORMATION (Tsa)
Silty SAND, fine- to medium-grained, light grayish brown,wet, very dense, trace clay. (continued)@ 25 ft. grades to fine-grained.
@ 30 ft. same.
Total Depth = 30.8 ft.
Groundwater encountered during drilling at 15 feet;gorudnwater measured at completion of drilling at 13.5 feet.No caving.
Backfilled in accordance with SDCDEH requirements.
44-50/2"
25-50/4"
SPT
SPT
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)25
30 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 2 OF 2
BORING NUMBER B-2
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:49 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 BORING LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
OLD PARALIC DEPOSITS (Qop)
Silty SAND, fine-grained, reddish brown, moist, mediumdense.
@ 2 ft. grades to grayish brown.
Clayey SAND, fine-grained, light yellowish gray, mottledyellow, very dense.
Silty SAND, fine-grained, light grayish brown, yellow, verydense.
@ 15 ft. grades to light gray, fine- to medium-grained, verydense, saturated, trace coarse sand. Groundwater.
SANTIAGO FORMATION (Tsa)
Silty SAND, fine-grained, tan to light yellowish gray, wet,very dense, trace clay.
15-29-49(78)
12-38-50/3"
6-9-20
(29)
16-50/5"
SPT
MC
SPT
MC
SM
SC
SM
SM EI
NOTES
GROUND ELEVATION 41 ft
LOGGED BY AB
DRILLING METHOD Hollow Stem Auger
HOLE SIZE 8
DRILLING CONTRACTOR Baja Exploration GROUND WATER LEVELS:
CHECKED BY PJD
DATE STARTED 3/18/19 COMPLETED 3/18/19
AT TIME OF DRILLING 15.00 ft / Elev 26.00 ft
AT END OF DRILLING 9.00 ft / Elev 32.00 ft
AFTER DRILLING ---
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)0
5
10
15
20
25 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
(Continued Next Page)PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 1 OF 2
BORING NUMBER B-3
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:49 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 BORING LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
SANTIAGO FORMATION (Tsa)
Silty SAND, fine-grained, tan to light yellowish gray, wet,very dense, trace clay. (continued)@ 25 ft. same, micaceous.
@ 30 ft. same.
Total Depth = 30.8 ft.
Groundwater encountered during drilling at 15 feet;groundwater measured at completion of drilling at 9 feet.No caving.
Backfilled in accordance with SDCDEH requirements.
23-43-50/3"
32-50/4"
SPT
MC
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)25
30 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 2 OF 2
BORING NUMBER B-3
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:49 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 BORING LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
TOPSOIL
Silty SAND, fine- to medium-grained, dark reddish brown,slightly moist, loose.
ARTIFICIAL FILLWell graded SAND with silt, fine- to medium-grained,yellowish to reddish brown, moist, medium dense.
Total Depth = 3.1 ft.No groundwater.
No caving.Backfilled in accordance with SDCDEH requirements.
SM
SW
NOTES
GROUND ELEVATION 44 ft
LOGGED BY SS
DRILLING METHOD Hand Dug
HOLE SIZE 6.5
DRILLING CONTRACTOR GROUND WATER LEVELS:
CHECKED BY PJD
DATE STARTED 5/23/19 COMPLETED 5/23/19
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)0.0
2.5 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 1 OF 1
BORING NUMBER P-1
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:51 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 INFILTRATION LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
TOPSOIL
Silty SAND, fine-grained, dark brown, slightly moist, loose;abundant roots.
ARTIFICIAL FILL
Silty SAND, fine-grained, brown with grey brown to olivefragments, slightly moist to moist, loose to medium dense.
OLD PARALIC DEPOSITS, UNITS 6-7 (Qop6-7)
Silty to clayey SAND, fine-grained, grey brown to olive, ironoxide staining, moist, dense; with black manganese (?)nodules.
Total Depth = 4.1 ft.No groundwater.
No caving.Backfilled in accordance with SDCDEH requirements.
SM
SM
SC-SM
NOTES
GROUND ELEVATION 43 ft
LOGGED BY SS
DRILLING METHOD Hand Dug
HOLE SIZE 6.5
DRILLING CONTRACTOR GROUND WATER LEVELS:
CHECKED BY PJD
DATE STARTED 5/23/19 COMPLETED 5/23/19
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)0.0
2.5 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 1 OF 1
BORING NUMBER P-2
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:51 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 INFILTRATION LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
TOPSOIL
Silty SAND with gravel, fine- to medium-grained, darkbrown, moist, loose; gravel is angular to 1-inch size.
ARTIFICIAL FILL
Silty SAND, fine- to medium-grained, dark brown, moist,loose.
OLD PARALIC DEPOSITS, UNITS 6-7 (Qop6-7)Silty to clayey SAND, fine- to medium-grained, grey brownto olive, iron oxide staining, moist, dense.
Total Depth = 4.9 ft.
No groundwater.No caving.
Backfilled in accordance with SDCDEH requirements.
SM
SM
SC-SM
NOTES
GROUND ELEVATION 41 ft
LOGGED BY SS
DRILLING METHOD Hand Dug
HOLE SIZE 6.5
DRILLING CONTRACTOR GROUND WATER LEVELS:
CHECKED BY PJD
DATE STARTED 5/23/19 COMPLETED 5/23/19
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
MATERIAL DESCRIPTION
BLOWCOUNTS(N VALUE)GRAPHICLOGDEPTH(ft)0.0
2.5 SAMPLE TYPENUMBERLIQUIDLIMITPLASTICLIMITPLASTICITYINDEXATTERBERGLIMITS
PLASTICITYINDEXDRY UNIT WT.(pcf)MOISTURECONTENT (%)SATURATION (%)FINES CONTENT(%)USCSOTHER TESTSPAGE 1 OF 1
BORING NUMBER P-3
AGS BORING LOG V2 - GINT STD US LAB.GDT - 3/17/21 08:51 - Z:\PROJECT FILES\1809-04 CARLSBAD STATION MCKELLER MCGOWAN\LAB AND BORINGS\1809-04 INFILTRATION LOGS.GPJCLIENT McKellar McGowan, LLC
PROJECT NUMBER 1809-04
PROJECT NAME Carlsbad Station
PROJECT LOCATION Carlsbad, CA
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
APPENDIX C
LABORATORY TEST RESULTS
March 16, 2021 Page C-1
P/W 1809-04 Report No. 1809-04-B-7
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
APPENDIX C
LABORATORY TEST RESULTS
Classification
Soils were visually and texturally classified in accordance with the Unified Soil Classification System
(USCS) in general accordance with ASTM D2488. Soil classifications are indicated on the boring logs
in Appendix B.
Moisture and Density
The moisture content and density of samples obtained from the exploratory excavations was evaluated
in accordance with ASTM D 2216. The test results are presented on the boring logs in Appendix B.
Expansion Index
The expansion index of selected materials was evaluated in general accordance with ASTM D4829.
Specimens were molded under a specified compactive energy at approximately 50 percent saturation (±1
percent). The prepared 1-inch thick by 4-inch diameter specimens were loaded with a surcharge of 144
pounds per square foot and were inundated with tap water. Readings of volumetric swell were made for
a period of 24 hours. The results of these tests are presented on Figure C-1.
Consolidation Tests
A consolidation test was performed on a selected sample in general accordance with the latest version of
ASTM D 2435. The sample was inundated during testing to represent adverse field conditions. The
percent consolidation for each load cycle was recorded as a ratio of the amount of vertical compression
to the original height of the sample. The test results are presented on Figure C-2.
Direct Shear
Direct shear tests were performed on undisturbed samples in general accordance with ASTM D3080
to evaluate the shear strength characteristics of selected materials. The samples were inundated during
shearing to represent adverse field conditions. The results are shown on Figure C-3.
Soil Corrosivity
A soil pH, and resistivity test were performed on a representative sample in general accordance with
California Test (CT)643. The chloride content of a selected sample was evaluated in general accordance
with CT422. The sulfate content of a selected sample was evaluated in general accordance with CT417.
The test results are presented on Figure C-4.
EXPANSION INDEX - ASTM D4829 AGS FORM E-6
Project Name: Antique Block Excavation/Tract: B-3
Location: Carlsbad Depth/Lot: 20-21 ft
P/W: 1809-04 Description: SM
Date: 4/8/19 Tested by: FV
Checked by: AB
Expansion Index - ASTM D4829
Initial Dry Density (pcf): 116.2
Initial Moisture Content (%): 8.3
Initial Saturation (%): 49.8
Final Dry Density (pcf): 115.2
Final Moisture Content (%): 16.5
Final Saturation (%):96.5
Expansion Index: 9
Expansion Potential: Very Low
ASTM D4829 - Table 5.3
Expansion Index
0 - 20
21 - 50
51 - 90
91 - 130
>130 Very High
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
Expansion Potential
Very Low
Low
Medium
High
EI_B-3_20-21 ft_1809-04_04-08-19_FV FIGURE C-1
CONSOLIDATION - ASTM D2435 AGS Form E-3
Project Name: Antique Block Excavation: B-1
Depth: 15-16.5 ftLocation: Carlsbad
Project No: 1809-04 Description: SM
Date: 3/26/2019 By: FV
After Test
Water Content, w 18.9% 18.2%
Void Ratio, e 0.57 0.56
Saturation, S 89% 88%
Dry Density (pcf) 107.2 108.1
Wet Density (pcf) 127.5 127.8
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
Test Conditions Before Test
-7
-6
-5
-4
-3
-2
-1
0
1
0.1 1 10 100
Consolidation (%)Normal Pressure (ksf)
Consolidation-Pressure Curve
FIGURE C-2
Project Name: Antique Block Excavation: B-2
Location: Carlsbad Depth: 15-16.5 ft
Project No.: 1809-04 Tested by: FV
Date:Reviewed by: AB
Samples Tested 123 Soil Type: SM
Intial Moisture (%) 13.9 13.9 13.9 Test: Undisturbed
Initial Dry Density (pcf) 113.4 113.2 113.7 Method: Drained
Normal Stress (psf) 1000 2000 4000 Consolidation: Yes
Peak Shear Stress (psf) 1008 1884 3756 Saturation: Yes
Ult. Shear Stress (psf) 768 1428 3264 Shear Rate (in/min):0.01
Strength Parameters Peak Ultimate
Friction Angle, phi (deg)42 38
Cohesion (psf)125 0
ADVANCED GEOTECHNICAL SOLUTIONS, INC.
DIRECT SHEAR - ASTM D3080
3/27/2019
‐0.02
‐0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.00 0.10 0.20 0.30Vertical Deformation (in)Displacement (in)
Vertical Deformation v. Displacement
4000
2000
10000
500
1000
1500
2000
2500
3000
3500
4000
0.00 0.10 0.20 0.30Shear Stress (psf)Displacement (in)
Shear Stress v. Displacement
4000
2000
1000
0
500
1000
1500
2000
2500
3000
3500
4000
0 500 1000 1500 2000 2500 3000 3500 4000 4500Shear Stress (psf)Normal Stress (psf)
Peak
Peak
Ultimate
Ultimate
FIGURE C-3
ANAHEIM TEST LAB, INC
196 Technology Drive, Unit D
Irvine, CA 92618 Phone (949)336-6544
DATE: 04/08/2019 Advanced Geotechnical Solutions, Inc. 485 Corporate Ave., Suite B P.O. NO.: Chain of Custody Escondido, CA 92029 LAB NO.: C-2779
SPECIFICATION: CTM-417/422/643
MATERIAL: Soil
Project No.: 1809-04
Project: Antique Block Date sampled: 03/08/2019
Sample Location: On Site
ANALYTICAL REPORT
CORROSION SERIES
SUMMARY OF DATA
pH SOLUBLE SULFATES SOLUBLE CHLORIDES MIN. RESISTIVITY
per CT. 417 per CT. 422 per CT. 643
ppm ppm ohm-cm
B-1 @ 20’-21’7.5 148 141 1,000
RESPECTFULLY SUBMITTED
________________________________
WES BRIDGER LAB MANAGER
FIGURE C-4