HomeMy WebLinkAboutSDP 2024-0001; THE ROOSEVELT; UPDATE GEOTECHNICAL INVESTIGATION; 2025-07-17UPDATE
GEOTECHNICAL INVESTIGATION
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
PREPARED FOR
JULY 17, 2025
PROJECT NO. G3112-52-01
FABRIC
6960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone (858) 558-6900 ■ www.geoconinc.com
Project No. G3112-52-01
July 17, 2025
Fabric Investments
2727 Roosevelt Street, Suite B
Carlsbad, California 92008
Attention: Mr. Brandan Foote
Subject: UPDATE GEOTECHNICAL INVESTIGATION
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
Dear Mr. Foote:
In accordance with your request and authorization of our Proposal No. LG-23145 dated March 30, 2023,
we herein submit the results of our update geotechnical investigation for the subject project. We
performed our investigation to evaluate the underlying soil and geologic conditions and potential
geologic hazards, and to assist in the design of the proposed building and associated improvements.
The accompanying report presents the results of our study and conclusions and recommendations
pertaining to geotechnical aspects of the proposed project. The site is suitable for the proposed buildings
and improvements provided the recommendations of this report are incorporated into the design and
construction of the planned project.
Should you have questions regarding this report, or if we may be of further service, please contact the
undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Nikolas Garcia
Senior Staff Engineer
Michael C. Ertwine
CEG 2659
Matt Love
GE 3238
Joseph Vettel
GE 2401
NG:MCE:ML:JJV:arm
(e-mail) Addressee
GEOCON
INCORPORATED
G E OT E CHN I CAL ■E NV I RONMENTA L ■ MA T ER I A L S
TABLE OF CONTENTS
1.PURPOSE AND SCOPE ................................................................................................................. 1
2.SITE AND PROJECT DESCRIPTION ........................................................................................... 2
3.GEOLOGIC SETTING .................................................................................................................... 3
4.SOIL AND GEOLOGIC CONDITIONS ........................................................................................ 4
4.1 Undocumented Fill (Qudf) .................................................................................................... 5
4.2 Old Paralic Deposits (Qop) .................................................................................................... 5
4.3 Santiago Formation (Tsa) ...................................................................................................... 5
5.GROUNDWATER .......................................................................................................................... 5
6.GEOLOGIC HAZARDS ................................................................................................................. 6
6.1 Faulting and Seismicity ......................................................................................................... 6
6.2 Ground Rupture ..................................................................................................................... 7
6.3 Liquefaction ........................................................................................................................... 7
6.4 Storm Surge, Tsunamis, and Seiches ..................................................................................... 8
6.5 Hydrocompression ................................................................................................................. 8
7.CONCLUSIONS AND RECOMMENDATIONS ........................................................................... 9
7.1 General ................................................................................................................................... 9
7.2 Excavation and Soil Characteristics .................................................................................... 10
7.3 Grading ................................................................................................................................ 11
7.4 Subdrains ............................................................................................................................. 13
7.5 Temporary Excavations ....................................................................................................... 13
7.6 Seismic Design Criteria – 2022 California Building Code .................................................. 14
7.7 Shallow Foundations ........................................................................................................... 15
7.8 Concrete Slabs-On-Grade .................................................................................................... 17
7.9 Exterior Concrete Flatwork ................................................................................................. 19
7.10 Retaining Walls ................................................................................................................... 20
7.11 Lateral Loading .................................................................................................................... 23
7.12 Preliminary Pavement Recommendations ........................................................................... 24
7.13 Site Drainage and Moisture Protection ................................................................................ 28
7.14 Grading and Foundation Plan Review ................................................................................. 28
7.15 Testing and Observation Services During Construction ...................................................... 28
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS Figure 1, Geologic Map Figure 2, Geologic Cross Section
APPENDIX A FIELD INVESTIGATION
APPENDIX B LABORATORY TESTING
APPENDIX C RECOMMENDED GRADING SPECIFICATIONS
LIST OF REFERENCES
Geocon Project No. G3112-52-01 - 1 - July 17, 2025
UPDATE GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the results of our update geotechnical investigation for a new mixed-use building
located within the Carlsbad Village area in the City of Carlsbad, California (see Vicinity Map).
Vicinity Map
The purpose of the update geotechnical investigation is to evaluate the surface and subsurface soil
conditions and general site geology, and to identify geotechnical constraints that may affect development
of the property including faulting, liquefaction and seismic shaking based on the 2022 CBC seismic
design criteria. In addition, we provided recommendations for remedial grading, shallow foundations,
concrete slab-on-grade, concrete flatwork, pavement and retaining walls.
The scope of this update investigation included reviewing readily available published and unpublished
geologic literature (see List of References), performing engineering analyses and preparing this report.
We drilled 2 exploratory borings to a maximum depth of about 20 feet, performed percolation/
infiltration testing, sampled soil and performed laboratory testing. Appendix A presents the exploratory
boring logs and details of the field investigation. The details of the laboratory tests and a summary of
the test results are shown in Appendix B and on the boring logs in Appendix A.
Geocon Project No. G3112-52-01 - 2 - July 17, 2025
2. SITE AND PROJECT DESCRIPTION
The property currently is developed with a 2-story commercial building with accommodating utilities,
landscaping and surface parking consisting of concrete pavement. A landscape area is located west of
the building that is accessed from a gate on the south from the parking lot. The site is located within the
Carlsbad Village neighborhood and accessed by Roosevelt Street. The property is west of Roosevelt
Street, north of a mobile home site, west of a car wash, and south of a parking lot. Existing grades are
relatively flat with elevations of approximately 40 to 42 feet Mean Sea Level (MSL) across the site. The
Existing Site Plan shows the current site conditions.
Existing Site Plan
We understand the project will consist of demolishing the existing building and constructing a 3-story
multi-use office and residential building supported on a shallow foundation system with a concrete slab
on grade. Access to the property would be from Roosevelt Street on the southeastern portion of the
property. The southern half of the first floor of the building would consist of tuck-under parking. The
Conceptual Plan shows the planned building and improvements.
Geocon Project No. G3112-52-01 - 3 - July 17, 2025
Conceptual Plan
The locations, site descriptions, and proposed development are based on our site reconnaissance, review
of published geologic literature, field investigations, and discussions with project personnel. If
development plans differ from those described herein, Geocon Incorporated should be contacted for
review of the plans and possible revisions to this report.
3. GEOLOGIC SETTING
Regionally, the site is in the Peninsular Ranges geomorphic province. The province is bounded by the
Transverse Ranges to the north, the San Jacinto Fault Zone on the east, the Pacific Ocean coastline on
the west, and the Baja California on the south. The province is characterized by elongated northwest-
trending mountain ridges separated by straight-sided sediment-filled valleys. The northwest trend is
further reflected in the direction of the dominant geologic structural features of the province that are
northwest to west-northwest trending folds and faults, such as the nearby Rose Canyon fault zone.
Locally, the site is within the coastal plain of San Diego County. The coastal plain is underlain by a thick
sequence of relatively undisturbed and non-conformable sedimentary bedrock units that thicken to the west
and range in age from Upper Cretaceous-age through the Pleistocene-age which have been deposited on
Cretaceous- to Jurassic-age igneous and volcanic bedrock. Geomorphically, the coastal plain is
characterized by a series of 21, stair-stepped marine terraces (younger to the west) that have been dissected
by west flowing rivers. The coastal plain is a relatively stable block that is dissected by relatively few faults
consisting of the potentially active La Nacion Fault Zone and the active Rose Canyon Fault Zone.
Geocon Project No. G3112-52-01 - 4 - July 17, 2025
The site is located in the western margins of the coastal plain. Marine sedimentary units make up the
geologic sequence at the site and consist of Pleistocene-age Old Paralic Deposits, (formerly described
as Terrace Deposits), and the Eocene-age Santiago Formation. Very Old Paralic Deposits Units 6-7, and
Units 1 &2 (formerly described as Terrace Deposits) are mapped to the east of the site, respectively. The
Paralic Deposits (Terrace Deposits) are shallow marine deposits consisting of sand and silty sands
interfingered with silt and clay. The Santiago Formation generally consists of marine and nonmarine
which consist of silty sandstones and sandy claystone with zones of cemented gravel and cemented beds.
A Regional Geologic Map is presented below.
Regional Geologic Map
4. SOIL AND GEOLOGIC CONDITIONS
We encountered one surficial soil (consisting of undocumented fill) and two geologic formations
(consisting of Old Paralic Deposits and the Santiago Formation) during our field investigation. The
occurrence, distribution and description of each unit encountered are shown on the Geologic Map,
Figure 1, and the boring logs in Appendix A. The Geologic Cross-Section, Figure 2, shows the
approximate subsurface relationship between the geologic units. We prepared the geologic cross-section
using interpolation between exploratory excavations and observations; therefore, actual geotechnical
conditions may vary from those illustrated and should be considered approximate. The surficial soils
and geologic units are described herein in order of increasing age.
Legend
QopG-7 .. 0ld Paralic Deposits (Unit 1-2)
Qop,-2 .. 0ld Paralic Deposits (Unit 6-7)
Geocon Project No. G3112-52-01 - 5 - July 17, 2025
4.1 Undocumented Fill (Qudf)
We encountered fill to depths ranging from about 2 to 3 feet from existing grade in the exploratory
borings. The fill is likely associated with the previous grading operations performed during the original
development of the property. The fill is generally composed of loose to medium dense, silty sand and
sandy clay. The undocumented fill is not considered suitable for additional fill or structural loads.
Remedial grading of the undocumented fill will be required as discussed herein.
4.2 Old Paralic Deposits (Qop)
Pleistocene-age Old Paralic Deposits (Units 6-7) exist below the undocumented fill across the site to
depths from approximately 15 to 17 feet below existing grades. These deposits generally consist of
medium dense to dense, light to dark reddish brown and yellowish brown, silty to clayey, fine to coarse
sand. Based on laboratory test results from this and nearby sites, the Old Paralic Deposits possess a
“very low” to “low” expansion potential (expansion index of 50 or less) and a “S0” sulfate class. The
Old Paralic Deposits are considered acceptable to support the planned fill and foundation loads for the
development.
4.3 Santiago Formation (Tsa)
We encountered Tertiary-age, middle Eocene-age, Santiago Formation underlying the Old Paralic
Deposits at depths ranging from 15 to 17 feet below existing grades. The Santiago Formation
encountered generally consists of very dense, silty to clayey sandstone and very stiff to hard, sandy
claystone. We do not expect Santiago Formation will be encountered during construction unless
subterranean levels or deep underground utilities exceeding approximately 15 feet in depth are proposed.
The Santiago Formation is considered suitable to support additional loads from fill and the planned
development.
5. GROUNDWATER
We encountered perched groundwater during the field investigation at depths of 11 and 15 feet (30 and
27 feet MSL) in Borings B-1 and B-2, respectively in the Old Paralic Deposits. Static groundwater levels
are likely close to sea level (about 40 feet below existing grades) due to the proximity of the Pacific
Ocean.Perched groundwater should be expected if subterranean levels are proposed and in excavations
for deeper utilities. It is not uncommon for groundwater or seepage conditions to develop where none
previously existed. Groundwater and seepage is dependent on seasonal precipitation, irrigation, land
use, among other factors, and varies as a result. Proper surface drainage will be important to future
performance of the project. Table 5 presents the boring locations and depths/ elevations of the
groundwater encountered on the subject site.
Geocon Project No. G3112-52-01 - 6 - July 17, 2025
TABLE 5 RECORDED PERCHED GROUNDWATER ELEVATION
Boring No. Date Recorded Approximate Depth of Perched Groundwater Below Existing Grade (feet)
B-1 4/20/2023 11
B-2 4/20/2023 15
6. GEOLOGIC HAZARDS
6.1 Faulting and Seismicity
A review of the referenced geologic materials and our knowledge of the general area indicate that the
site is not underlain by active, potentially active, or inactive faults. An active fault is defined by the
California Geological Survey (CGS) as a fault showing evidence for activity within the last
11,700 years. The site is not located within a State of California Earthquake Fault Zone.
The USGS has developed a program to evaluate the approximate location of faulting in the area of properties.
The following figure shows the location of the existing faulting in the San Diego County and Southern
California region. The fault traces are shown as solid, dashed and dotted that represent well-constrained,
moderately constrained and inferred, respectively. The fault line colors represent fault with ages less than 150
years (red), 15,000 years (orange), 130,000 years (green), 750,000 years (blue) and 1.6 million years (black).
Faults in Southern California
Geocon Project No. G3112-52-01 - 7 - July 17, 2025
The San Diego County and Southern California region is seismically active. The following figure
presents the occurrence of earthquakes with a magnitude greater than 2.5 from the period of 1900
through 2015 according to the Bay Area Earthquake Alliance website.
Earthquakes in Southern California
Considerations important in seismic design include the frequency and duration of motion and the soil
conditions underlying the site. Seismic design of structures should be evaluated in accordance with the
California Building Code (CBC) guidelines currently adopted by the local agency.
6.2 Ground Rupture
Ground surface rupture occurs when movement along a fault is sufficient to cause a gap or rupture where
the upper edge of the fault zone intersects the ground surface. The potential for ground rupture is
considered to be very low due to the absence of active faults at the subject site.
6.3 Liquefaction
Liquefaction typically occurs when a site is in a zone with seismic activity, onsite soils are cohesionless
or silt/clay with low plasticity, groundwater is encountered within 50 feet of the surface and soil relative
densities are less than about 70 percent. If the four previous criteria are met, a seismic event could result
in a rapid pore water pressure increase from the earthquake-generated ground accelerations. Due to the
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Geocon Project No. G3112-52-01 - 8 - July 17, 2025
very dense nature of the underlying Old Paralic Deposits and Santiago Formation, liquefaction potential
for the site is considered very low.
6.4 Storm Surge, Tsunamis, and Seiches
Storm surges are large ocean waves that sweep across coastal areas when storms make landfall. Storm
surges can cause inundation, severe erosion and backwater flooding along the water front. The site is
located over 2,000 feet from the Pacific Ocean and 1,000 feet from Buena Vista Lagoon and is at an
elevation of about 42 feet or greater above Mean Sea Level (MSL). Therefore, the potential of storm
surges affecting the site is considered low.
A tsunami is a series of long period waves generated in the ocean by a sudden displacement of large
volumes of water. Causes of tsunamis include underwater earthquakes, volcanic eruptions, or offshore
slope failures. The subject site is not located within the Tsunami Inundation Map for Emergency
Planning therefore, the potential for the site to be affected by a tsunami is negligible due to the distance
from the Pacific Ocean, Buena Vista Lagoon and the site elevation.
A seiche is a run-up of water within a lake or embayment triggered by fault- or landslide-induced ground
displacement. The site is not located in the vicinity of or downstream from such bodies of water.
Therefore, the risk of seiches affecting the site is negligible.
6.5 Hydrocompression
Hydrocompression is the tendency of unsaturated soil structure to compression upon wetting resulting
in the overall settlement of the effected soil and overlying foundations or improvements supported
thereon. Potentially compressible surficial soil underlying the proposed structures and existing fill is
typically removed and recompacted during remedial site grading. However, if compressible soil is left
in-place, a potential for settlement due to hydrocompression of the soil exists. The potential for
hydrocompression can be mitigated by remedial grading and the use of stiffer foundation systems. Based
on the laboratory test results, the potential for hydrocompression ranges from about 0.9 percent to
1.8 percent with an average of 1.4 percent under high loading conditions in the Old Paralic Deposits
located at a depth of 2 to 17 feet (approximate elevations of 40 to 23 feet MSL). If the Old Paralic
Deposits are not removed to the Santiago Formation and are heavily loaded and become wetted, we
expect the potential amount of settlement due to hydrocompression could be up to 2.5 inches. Therefore,
it will be important to not allow infiltration on the property due to the hydrocompression potential.
Geocon Project No. G3112-52-01 - 9 - July 17, 2025
7. CONCLUSIONS AND RECOMMENDATIONS
7.1 General
7.1.1 We did not encounter soil or geologic conditions during our exploration that would preclude
the proposed development, provided the recommendations presented herein are followed and
implemented during design and construction. We should update this report when development
plans have been prepared (i.e. grading plans). We can provide supplemental recommendations
if we observe variable or undesirable conditions during construction, or if the proposed
construction will differ from that anticipated herein. Table 7.1 provides a summary of our
conclusions and recommendations for the proposed project.
TABLE 7.1
SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS
Attribute Conclusion/Recommendations
Existing Geologic Hazards Strong Seismic Shaking
Hydrocompression
Existing Geologic Units
Undocumented Fill (Requiring Remedial Grading)
Old Paralic Deposits (Suitable for Support)
Santiago Formation (Suitable for Support)
Groundwater Perched Groundwater
11 and 15 Feet Below Existing Grades
Excavations Surficial Soil – Moderate to Difficult
Expansion Index 50 or Less
Water-Soluble Sulfate Content “S0”
Drainage Maintain Drainage As Discussed Herein
7.1.2 Except for possible moderate to strong seismic shaking, we did not observe or know of
significant geologic hazards to exist on the site that would adversely affect the proposed
project.
7.1.3 The undocumented fill is potentially compressible and unsuitable in their present condition
for the support of compacted fill or settlement-sensitive improvements. Remedial grading of
these materials should be performed as discussed herein. The Old Paralic Deposits and
Santiago Formation are considered suitable for the support of proposed fill and structural
loads.
7.1.4 We encountered perched groundwater within the Old Paralic Deposits at a depth of
approximately 11 to 15 feet below the existing ground surface (approximate elevation of 30
Geocon Project No. G3112-52-01 - 10 - July 17, 2025
to 27 feet above MSL). Perched groundwater will likely have a significant influence on
construction of deep utilities and subterranean structures (if proposed).
7.1.5 Excavation of the undocumented fill, Old Paralic Deposits, and Santiago Formation should
generally be possible with moderate to heavy effort using conventional, heavy-duty
equipment during grading and trenching operations. We expect very heavy effort with
possible refusal in localized areas for excavations into strongly cemented portions of the
Santiago Formation; however, we do not expect excavations will extend into the Santiago
Formation.
7.1.6 Proper drainage should be maintained in order to preserve the engineering properties of the
fill in both the building pads and slope areas. Recommendations for site drainage are provided
herein.
7.1.7 We performed a storm water management investigation under a separate report to help
evaluate the potential for infiltration on the property. The project civil engineer should use
that report to help design the storm water management devices. We expect a “No infiltration”
condition exists due to the potential of hydrocollapse.
7.1.8 Based on our review of the project plans, we opine the planned development can be
constructed in accordance with our recommendations provided herein. We do not expect the
planned development will destabilize or result in settlement of adjacent properties if properly
constructed.
7.1.9 Surface settlement monuments and canyon subdrains will not be required on this project.
7.2 Excavation and Soil Characteristics
7.2.1 Excavation of the in-situ soil should be possible with moderate to heavy effort using
conventional heavy-duty equipment. Excavation of the formational materials will require very
heavy effort and may generate oversized material using conventional heavy-duty equipment
during the grading operations. Oversized rock (rocks greater than 12 inches in dimension)
may be generated with the Old Paralic Deposits materials that can be incorporated into
landscape use or deep compacted fill areas, if available. The grading and improvement
contractors should review this report and evaluate the proper equipment to use for the planned
excavations.
7.2.2 The soil encountered in the field investigation is “non-expansive” (expansion index [EI] of
20 or less) as defined by 2022 California Building Code (CBC) Section 1803.5.3. Based on
Geocon Project No. G3112-52-01 - 11 - July 17, 2025
experience in the area, we expect most of the soil encountered will possess a “very low” to
“low” expansion potential (EI of 50 or less) in accordance with ASTM D 4829. Table 7.2
presents soil classifications based on the expansion index.
TABLE 7.2
EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (EI) ASTM D 4829 Expansion
Classification
2022 CBC Expansion
Classification
0 – 20 Very Low Non-Expansive
21 – 50 Low
Expansive 51 – 90 Medium
91 – 130 High
Greater Than 130 Very High
7.2.3 We performed laboratory tests on samples of the site materials to evaluate the percentage of
water-soluble sulfate content. Appendix B presents results of the laboratory water-soluble
sulfate content tests. The test results indicate the on-site materials at the locations tested
possess “S0” sulfate exposure to concrete structures as defined by 2022 CBC Section 1904
and ACI 318-19 Chapter 19.
7.2.4 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, further
evaluation by a corrosion engineer may be performed if improvements susceptible to
corrosion are planned.
7.3 Grading
7.3.1 Grading should be performed in accordance with the recommendations provided in this report,
the Recommended Grading Specifications contained in Appendix C and the local grading
ordinance. Geocon Incorporated should observe the grading operations on a full-time basis
and provide testing during the fill placement.
7.3.2 Prior to commencing grading, a preconstruction conference should be held at the site with the
agency inspector, developer, grading and underground contractors, civil engineer, and
geotechnical engineer in attendance. Special soil handling and/or the grading plans can be
discussed at that time.
7.3.3 Site preparation should begin with the removal of deleterious material, debris, and vegetation.
The depth of vegetation removal should be such that material exposed in cut areas or soil to
be used as fill is relatively free of organic matter. Material generated during stripping and/or
Geocon Project No. G3112-52-01 - 12 - July 17, 2025
site demolition should be exported from the site. Asphalt and concrete should not be mixed
with the fill soil unless approved by the Geotechnical Engineer.
7.3.4 Abandoned foundations and buried utilities (if encountered) should be removed and the
resultant depressions and/or trenches should be backfilled with properly compacted material
as part of the remedial grading.
7.3.5 The undocumented fill should be excavated and properly compacted fill should be placed
within the proposed development area. The removals should extend at least 10 feet outside of
the planned building envelope, where possible. The removals can be terminated when
competent formational materials are encountered.
7.3.6 In areas of proposed improvements outside of the building areas, the upper 1 to 2 feet of
existing soil should be processed, moisture conditioned as necessary and recompacted. Deeper
excavations may be required in areas where loose or saturated materials are encountered. The
excavations should extend at least 2 feet laterally outside of the improvement area, where
possible. Table 7.3.1 provides a summary of the remedial grading recommendations.
TABLE 7.3.1
SUMMARY OF REMEDIAL GRADING RECOMMENDATIONS
Area Remedial Grading Excavation Requirements
Shallow Foundations Embedded in Old Paralic
Deposits
Excavate Undocumented Fill to Expose Old
Paralic Deposits
Site Development Process Upper 1 to 2 Feet of Existing Materials
Lateral Grading Limits 10 Feet Outside of Buildings
2 Feet Outside of Improvement Areas
Exposed Bottoms of Excavations Scarify Upper 12 Inches
7.3.7 Some areas of overly wet and saturated soil could be encountered due to the existing landscape
and pavement areas. The saturated soil would require additional effort prior to placement of
compacted fill or additional improvements. Stabilization of the soil would include scarifying
and air-drying, removing and replacement with drier soil, use of stabilization fabric (e.g.
Tensar NX750 or other approved fabric), or chemical treating (i.e. cement or lime treatment).
7.3.8 The site should then be brought to final subgrade elevations with fill compacted in layers. In
general, the existing soil is suitable for use from a geotechnical engineering standpoint, as fill,
if relatively free from vegetation, debris and other deleterious material. Layers of fill should
Geocon Project No. G3112-52-01 - 13 - July 17, 2025
be about 6 to 8 inches in loose thickness and no thicker than will allow for adequate bonding
and compaction. Fill, including backfill and scarified ground surfaces, should be compacted
to a dry density of at least 90 percent of the laboratory maximum dry density near to slightly
above optimum moisture content in accordance with ASTM D 1557. Fill materials placed
below optimum moisture content may require additional moisture conditioning prior to
placing additional fill. The upper 12 inches of subgrade soil underlying pavement should be
compacted to a dry density of at least 95 percent of the laboratory maximum dry density near
to slightly above optimum moisture content shortly before paving operations.
7.3.9 Import fill (if necessary) should consist of the characteristics presented in Table 7.3.2. Geocon
Incorporated should be notified of the import soil source and should perform laboratory
testing of import soil prior to its arrival at the site to determine its suitability as fill material.
TABLE 7.3.2
SUMMARY OF IMPORT FILL RECOMMENDATIONS
Soil Characteristic Values
Expansion Potential “Very Low” to “Low” (Expansion Index of 50 or less)
Particle Size Maximum Dimension Less Than 3 Inches
Generally Free of Debris
7.4 Subdrains
7.4.1 Except for retaining wall drains, we do not expect the installation of other subdrains.
7.5 Temporary Excavations
7.5.1 The recommendations included herein are provided for stable excavations. It is the
responsibility of the contractor and their competent person to ensure all excavations,
temporary slopes and trenches are properly constructed and maintained in accordance with
applicable OSHA guidelines in order to maintain safety and the stability of the excavations
and adjacent improvements. These excavations should not be allowed to become saturated or
to dry out. Surcharge loads should not be permitted to a distance equal to the height of the
excavation from the top of the excavation. The top of the excavation should be a minimum of
15 feet from the edge of existing improvements. Excavations steeper than those recommended
should be shored in accordance with applicable OSHA codes and regulations.
7.5.2 The stability of the excavations is dependent on the design and construction of the shoring
system and site conditions. Therefore, Geocon Incorporated cannot be responsible for site
safety and the stability of the proposed excavations.
Geocon Project No. G3112-52-01 - 14 - July 17, 2025
7.6 Seismic Design Criteria – 2022 California Building Code
7.6.1 Table 7.6.1 summarizes site-specific design criteria obtained from the 2022 California
Building Code (CBC; Based on the 2021 International Building Code [IBC] and ASCE 7-16),
Chapter 16 Structural Design, Section 1613 Earthquake Loads. We used the computer
program U.S. Seismic Design Maps, provided by the Structural Engineers Association (SEA)
to calculate the seismic design parameters. The short spectral response uses a period of 0.2
second. We evaluated the Site Class based on the discussion in Section 1613.2.2 of the 2022
CBC and Table 20.3-1 of ASCE 7-16. The values presented herein are for the risk-targeted
maximum considered earthquake (MCER).
TABLE 7.6.1
2022 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2022 CBC Reference
Site Class C Section 1613.2.2
MCER Ground Motion Spectral Response Acceleration – Class B (short), SS 1.079g Figure 1613.2.1(1)
MCER Ground Motion Spectral Response Acceleration – Class B (1 sec), S1 0.390g Figure 1613.2.1(3)
Site Coefficient, FA 1.200 Table 1613.2.3(1)
Site Coefficient, FV 1.500* Table 1613.2.3(2)
Site Class Modified MCER Spectral Response Acceleration (short), SMS 1.295g Section 1613.2.3 (Eqn 16-20)
Site Class Modified MCER Spectral Response Acceleration – (1 sec), SM1 0.586g* Section 1613.2.3 (Eqn 16-21)
5% Damped Design Spectral Response Acceleration (short), SDS 0.863g Section 1613.2.4 (Eqn 16-22)
5% Damped Design Spectral Response Acceleration (1 sec), SD1 0.390g* Section 1613.2.4 (Eqn 16-23)
7.6.2 Table 7.6.2 presents the mapped maximum considered geometric mean (MCEG) seismic
design parameters for projects located in Seismic Design Categories of D through F in
accordance with ASCE 7-16.
TABLE 7.6.2
ASCE 7-16 PEAK GROUND ACCELERATION
Parameter Value ASCE 7-16 Reference
Mapped MCEG Peak Ground Acceleration, PGA 0.476g Figure 22-9
Site Coefficient, FPGA 1.200 Table 11.8-1
Site Class Modified MCEG Peak Ground
Acceleration, PGAM 0.571g Section 11.8.3 (Eqn 11.8-1)
Geocon Project No. G3112-52-01 - 15 - July 17, 2025
7.6.3 Conformance to the criteria in Tables 7.6.1 and 7.6.2 for seismic design does not constitute
any kind of guarantee or assurance that significant structural damage or ground failure will
not occur in the event of a large earthquake. The primary goal of seismic design is to protect
life, not to avoid all damage, since such design may be economically prohibitive.
7.6.4 The project structural engineer and architect should evaluate the appropriate Risk Category
and Seismic Design Category for the planned structures. The values presented herein assume
a Risk Category of II and resulting in a Seismic Design Category D. Table 7.3.3 presents a
summary of the risk categories in accordance with ASCE 7-16.
TABLE 7.6.3
ASCE 7-16 RISK CATEGORIES
Risk Category Building Use Examples
I Low risk to Human Life at Failure Barn, Storage Shelter
II
Nominal Risk to Human Life at
Failure (Buildings Not Designated
as I, III or IV)
Residential, Commercial and Industrial
Buildings
III Substantial Risk to Human Life at
Failure
Theaters, Lecture Halls, Dining Halls,
Schools, Prisons, Small Healthcare
Facilities, Infrastructure Plants, Storage
for Explosives/Toxins
IV Essential Facilities
Hazardous Material Facilities,
Hospitals, Fire and Rescue, Emergency
Shelters, Police Stations, Power
Stations, Aviation Control Facilities,
National Defense, Water Storage
7.7 Shallow Foundations
7.7.1 The proposed structure can be supported on a shallow foundation system founded in the Old
Paralic Deposits. The foundations should extend through the compacted fill materials and be
embedded at least 6 inches into the formational materials. Foundations for the structure should
consist of continuous strip footings and/or isolated spread footings. Table 7.7 provides a
summary of the foundation design recommendations.
Geocon Project No. G3112-52-01 - 16 - July 17, 2025
TABLE 7.7
SUMMARY OF FOUNDATION RECOMMENDATIONS
Parameter Value
Minimum Continuous Foundation Width, WC 12 Inches
Minimum Isolated Foundation Width, WI 24 Inches (At Least 6 Inches Into Old Paralic Deposits)
Minimum Foundation Depth, D 24 Inches Below Lowest Adjacent Grade
Minimum Steel Reinforcing 4 No. 5 Bars, 2 Top and 2 Bottom
Allowable Bearing Capacity 4,000 psf
Bearing Capacity Increase 500 psf per Foot of Depth
300 psf per Foot of Width
Maximum Allowable Bearing Capacity 5,500 psf
Estimated Total Settlement 1 Inch
Estimated Differential Settlement ½ Inch in 40 Feet
Footing Size Used for Settlement 6-Foot Square
Design Expansion Index 50 or Less
7.7.2 The bearing capacity values presented herein are for dead plus live loads and may be increased
by one-third when considering transient loads due to wind or seismic forces.
7.7.3 The foundations should be embedded in accordance with the recommendations herein and the
Wall/Column Footing Dimension Detail. The embedment depths should be measured from
the lowest adjacent pad grade for both interior and exterior footings. Footings should be
deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from
the face of the slope (unless designed with a post-tensioned foundation system as discussed
herein).
Wall/Column Footing Dimension Detail
(!)0 z . -J: I-l-o a. ow 11. 0
SAND AND VAPOR
RETARDER IN
ACCORDANCE WITH ACI
FOOTING
WIDTH, We
PAD GRADE
Cl J: ~ I-I-a. Ow 00 11.
Geocon Project No. G3112-52-01 - 17 - July 17, 2025
7.7.4 Overexcavation of the footings and replacement with slurry can be performed in areas where
formational materials are not encountered at the bottom of the footing. Minimum two-sack
cement slurry can be placed in the excavations for the conventional foundations to the bottom
of proposed footing elevation.
7.7.5 We should observe the foundation excavations prior to the placement of reinforcing steel and
concrete to check that the exposed soil conditions are similar to those expected and that they
have been extended to the appropriate bearing strata. Foundation modifications may be
required if unexpected soil conditions are encountered.
7.7.6 Geocon Incorporated should be consulted to provide additional design parameters as required
by the structural engineer.
7.8 Concrete Slabs-On-Grade
7.8.1 Concrete slabs-on-grade for the structures should be constructed in accordance with
Table 7.8.
TABLE 7.8
MINIMUM CONCRETE SLAB-ON-GRADE RECOMMENDATIONS
Parameter Value
Minimum Concrete Slab Thickness 5 Inches
Minimum Steel Reinforcing No. 3 Bars 18 Inches on Center, Both Directions
Typical Slab Underlayment 3 to 4 Inches of Sand/Gravel/Base
Design Expansion Index 50 or Less
7.8.2 Slabs that may receive moisture-sensitive floor coverings or may be used to store moisture-
sensitive materials should be underlain by a vapor retarder. The vapor retarder design should
be consistent with the guidelines presented in the American Concrete Institute’s (ACI) Guide
for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). In
addition, the membrane should be installed in accordance with manufacturer’s
recommendations and ASTM requirements and installed in a manner that prevents puncture.
The vapor retarder used should be specified by the project architect or developer based on the
type of floor covering that will be installed and if the structure will possess a humidity
controlled environment.
7.8.3 The bedding sand thickness should be determined by the project foundation engineer,
architect, and/or developer. It is common to have 3 to 4 inches of sand in the southern
Geocon Project No. G3112-52-01 - 18 - July 17, 2025
California region. However, we should be contacted to provide recommendations if the
bedding sand is thicker than 6 inches. The foundation design engineer should provide
appropriate concrete mix design criteria and curing measures to assure proper curing of the
slab by reducing the potential for rapid moisture loss and subsequent cracking and/or slab
curl. We suggest that the foundation design engineer present the concrete mix design and
proper curing methods on the foundation plans. It is critical that the foundation contractor
understands and follows the recommendations presented on the foundation plans.
7.8.4 Some projects remove the sand layer below the slab in parking structure areas. This is
acceptable from a geotechnical engineering standpoint; however, relatively minor cracks
could form due to differential curing. Therefore, the structural engineer and/or the concrete
contractor should provide recommendations for proper curing techniques to help prevent
cracking.
7.8.5 Concrete slabs should be provided with adequate crack-control joints, construction joints
and/or expansion joints to reduce unsightly shrinkage cracking. The design of joints should
consider criteria of the American Concrete Institute (ACI) when establishing crack-control
spacing. Crack-control joints should be spaced at intervals no greater than 12 feet. Additional
steel reinforcing, concrete admixtures and/or closer crack control joint spacing should be
considered where concrete-exposed finished floors are planned.
7.8.6 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed foundation and slab subgrade soil should be moisturized to maintain a moist
condition as would be expected in any such concrete placement.
7.8.7 The concrete slab-on-grade recommendations are based on soil support characteristics only.
The project structural engineer should evaluate the structural requirements of the concrete
slabs for supporting expected loads.
7.8.8 The recommendations of this report are intended to reduce the potential for cracking of slabs
due to expansive soil (if present), differential settlement of existing soil or soil with varying
thicknesses. However, even with the incorporation of the recommendations presented herein,
foundations, stucco walls, and slabs-on-grade placed on such conditions may still exhibit
some cracking due to soil movement and/or shrinkage. The occurrence of concrete shrinkage
cracks is independent of the supporting soil characteristics. Their occurrence may be reduced
and/or controlled by limiting the slump of the concrete, proper concrete placement and curing,
and by the placement of crack control joints at periodic intervals, in particular, where re-
entrant slab corners occur.
Geocon Project No. G3112-52-01 - 19 - July 17, 2025
7.9 Exterior Concrete Flatwork
7.9.1 Exterior concrete flatwork not subject to vehicular traffic should be constructed in accordance
with the recommendations presented in Table 7.9. The recommended steel reinforcing would
help reduce the potential for offset of cracking.
TABLE 7.9
MINIMUM CONCRETE FLATWORK RECOMMENDATIONS
Expansion
Index, EI Minimum Steel Reinforcing* Options Minimum
Thickness
EI < 50 6x6-W2.9/W2.9 (6x6-6/6) Welded Wire Mesh 4 Inches No. 3 Bars 18 Inches On Center, Both Directions
*In excess of 8 feet square.
7.9.2 The subgrade soil should be properly moisturized and compacted prior to the placement of
steel and concrete. The subgrade soil should be compacted to a dry density of at least 90
percent of the laboratory maximum dry density near to slightly above optimum moisture
content in accordance with ASTM D 1557.
7.9.3 Even with the incorporation of the recommendations of this report, the exterior concrete
flatwork has a potential to experience some uplift due to expansive soil beneath grade. The
steel reinforcing should overlap continuously in flatwork to reduce the potential for vertical
offsets within flatwork. Additionally, flatwork should be structurally connected to the curbs,
where possible, to reduce the potential for offsets between the curbs and the flatwork.
7.9.4 Concrete flatwork should be provided with crack control joints to reduce and/or control
shrinkage cracking. Crack control spacing should be determined by the project structural
engineer based upon the slab thickness and intended usage. Criteria of the American Concrete
Institute (ACI) should be taken into consideration when establishing crack control spacing.
Subgrade soil for exterior slabs not subjected to vehicle loads should be compacted in
accordance with criteria presented in the grading section prior to concrete placement.
Subgrade soil should be properly compacted and the moisture content of subgrade soil should
be verified prior to placing concrete. Base materials will not be required below concrete
improvements.
7.9.5 Where exterior flatwork abuts the structure at entrant or exit points, the exterior slab should
be dowelled into the structure’s foundation stemwall. This recommendation is intended to
reduce the potential for differential elevations that could result from differential settlement or
Geocon Project No. G3112-52-01 - 20 - July 17, 2025
minor heave of the flatwork. Dowelling details should be designed by the project structural
engineer.
7.9.6 The recommendations presented herein are intended to reduce the potential for cracking of
exterior slabs as a result of differential movement. However, even with the incorporation of
the recommendations presented herein, slabs-on-grade will still crack. The occurrence of
concrete shrinkage cracks is independent of the soil supporting characteristics. Their
occurrence may be reduced and/or controlled by limiting the slump of the concrete, the use of
crack control joints and proper concrete placement and curing. Crack control joints should be
spaced at intervals no greater than 12 feet. Literature provided by the Portland Concrete
Association (PCA) and American Concrete Institute (ACI) present recommendations for
proper concrete mix, construction, and curing practices, and should be incorporated into
project construction.
7.10 Retaining Walls
7.10.1 Retaining walls should be designed using the values presented in Table 7.10.1. Soil with an
expansion index (EI) of greater than 50 should not be used as backfill material behind
retaining walls.
TABLE 7.10.1
RETAINING WALL DESIGN RECOMMENDATIONS
Parameter Value
Active Soil Pressure, A (Fluid Density, Level Backfill) 35 pcf
Active Soil Pressure, A (Fluid Density, 2:1 Sloping Backfill) 50 pcf
Seismic Pressure, S 15H psf
At-Rest/Restrained Walls Additional Uniform Pressure, RU (0 to 8 Feet High) 7H psf
At-Rest/Restrained Walls Additional Uniform Pressure, RL (8+ Feet High) 13H psf
Expected Expansion Index for the Subject Property EI<50
H equals the height of the retaining portion of the wall
7.10.2 The project retaining walls should be designed as shown in the Retaining Wall Loading
Diagram.
Geocon Project No. G3112-52-01 - 21 - July 17, 2025
Retaining Wall Loading Diagram
7.10.3 Unrestrained walls are those that are allowed to rotate more than 0.001H (where H equals the
height of the retaining portion of the wall) at the top of the wall. Where walls are restrained
from movement at the top (at-rest condition), an additional uniform pressure should be applied
to the wall. For retaining walls subject to vehicular loads within a horizontal distance equal
to two-thirds the wall height, a surcharge equivalent to 2 feet of fill soil should be added to
the upper 10 feet of the retaining wall.
7.10.4 The structural engineer should determine the Seismic Design Category for the project in
accordance with Section 1613 of the 2022 CBC or Section 11.6 of ASCE 7-16. For structures
assigned to Seismic Design Category of D, E, or F, retaining walls that support more than 6
feet of backfill should be designed with seismic lateral pressure in accordance with Section
1803.5.12 of the 2022 CBC. The seismic load is dependent on the retained height where H is
the height of the wall, in feet, and the calculated loads result in pounds per square foot (psf)
exerted at the base of the wall and zero at the top of the wall.
7.10.5 Retaining walls should be designed to ensure stability against overturning sliding, and
excessive foundation pressure. Where a keyway is extended below the wall base with the
intent to engage passive pressure and enhance sliding stability, it is not necessary to consider
active pressure on the keyway.
7.10.6 Drainage openings through the base of the wall (weep holes) should not be used where the
seepage could be a nuisance or otherwise adversely affect the property adjacent to the base of
the wall. The recommendations herein assume a properly compacted granular (EI of 90 or
less) free-draining backfill material with no hydrostatic forces or imposed surcharge load. The
IF PRESENT
RETAINING
WALL
SLAB
ACTIVE
PRESSURE
H (Feet)
FOOTING
SEISMIC
(IF
REQUIRED)
AT-REST/
RESTRAINED
(IF REQUIRED)
H s 8'
H>S'
~ psf ---
Geocon Project No. G3112-52-01 - 22 - July 17, 2025
retaining wall should be properly drained as shown in the Typical Retaining Wall Drainage
Detail. If conditions different than those described are expected, or if specific drainage details
are desired, Geocon Incorporated should be contacted for additional recommendations.
Typical Retaining Wall Drainage Detail
7.10.7 The retaining walls may be designed using either the active and restrained (at-rest) loading
condition or the active and seismic loading condition as suggested by the structural engineer.
Typically, it appears the design of the restrained condition for retaining wall loading may be
adequate for the seismic design of the retaining walls. However, the active earth pressure
combined with the seismic design load should be reviewed and also considered in the design
of the retaining walls.
7.10.8 In general, wall foundations should be designed in accordance with Table 7.10.2 and
embedded in properly compacted fill or Old Paralic Deposits. The proximity of the foundation
to the top of a slope steeper than 3:1 could impact the allowable soil bearing pressure.
Therefore, retaining wall foundations should be deepened such that the bottom outside edge
of the footing is at least 7 feet horizontally from the face of the slope.
TABLE 7.10.2
SUMMARY OF RETAINING WALL FOUNDATION RECOMMENDATIONS
Parameter Value
Minimum Retaining Wall Foundation Width 12 Inches
Minimum Retaining Wall Foundation Depth 12 Inches
Minimum Steel Reinforcing Per Structural Engineer
Allowable Bearing Capacity 2,000 psf
Bearing Capacity Increase 500 psf per Foot of Depth
300 psf per Foot of Width
Maximum Allowable Bearing Capacity 3,500 psf
Estimated Total Settlement 1 Inch
Estimated Differential Settlement ½ Inch in 40 Feet
H
PROPOSED
GRADE
CONCRETE BROWDITCH
OR
Fl 140N FILTER
RIC (OR EQUIVALENT)
PROPOSED
GRADE
4" DIA. PERFORATED SCHEDULE 40
PVC PIPE EXTENDED TO APPROVED
OUTLET
213 H
314" CRUSHED ROCK (1 CU. FT JFT.)
OR WRAP DRAINAGE PANEL
AROUND PIPE
FILTER FABRIC ENVELOPE
MIRAFI 140N OR EQUIVALENT
4" DIA. SCHEDULE 40 PERFORATED
PVC PIPE OR TOTAL DRAIN EXTENDED
TO APPROVED OUTLET
Geocon Project No. G3112-52-01 - 23 - July 17, 2025
7.10.9 The recommendations presented herein are generally applicable to the design of rigid concrete
or masonry retaining walls. In the event that other types of walls (such as mechanically
stabilized earth [MSE] walls, soil nail walls, or soldier pile walls) are planned, Geocon
Incorporated should be consulted for additional recommendations.
7.10.10 It is common to see retaining walls constructed in the areas of the elevator pits. The retaining
walls should be properly drained and designed in accordance with the recommendations
presented herein. If the elevator pit walls are not drained, the walls should be designed with
an increased active pressure with an equivalent fluid density of 90 pcf. It is also common to
see seepage and water collection within the elevator pit. The pit should be designed and
properly waterproofed to prevent seepage and water migration into the elevator pit.
7.10.11 Unrestrained walls will move laterally when backfilled and loading is applied. The amount of
lateral deflection is dependent on the wall height, the type of soil used for backfill, and loads
acting on the wall. The retaining walls and improvements above the retaining walls should be
designed to incorporate an appropriate amount of lateral deflection as determined by the
structural engineer.
7.10.12 Soil contemplated for use as retaining wall backfill, including import materials, should be
identified in the field prior to backfill. At that time, Geocon Incorporated should obtain
samples for laboratory testing to evaluate its suitability. Modified lateral earth pressures may
be necessary if the backfill soil does not meet the required expansion index or shear strength.
City or regional standard wall designs, if used, are based on a specific active lateral earth
pressure and/or soil friction angle. In this regard, on-site soil to be used as backfill may or
may not meet the values for standard wall designs. Geocon Incorporated should be consulted
to assess the suitability of the on-site soil for use as wall backfill if standard wall designs will
be used.
7.11 Lateral Loading
7.11.1 Table 7.11 should be used to help design the proposed structures and improvements to resist
lateral loads for the design of footings or shear keys. The allowable passive pressure assumes
a horizontal surface extending at least 5 feet, or three times the surface generating the passive
pressure, whichever is greater. The upper 12 inches of material in areas not protected by floor
slabs or pavement should not be included in design for passive resistance.
Geocon Project No. G3112-52-01 - 24 - July 17, 2025
TABLE 7.11
SUMMARY OF LATERAL LOAD DESIGN RECOMMENDATIONS
Parameter Value
Passive Pressure Fluid Density 350 pcf
Coefficient of Friction (Concrete and Soil) 0.35
Coefficient of Friction (Along Vapor Barrier) 0.2 to 0.25*
*Per manufacturer’s recommendations.
7.11.2 The passive and frictional resistant loads can be combined for design purposes. The lateral
passive pressures may be increased by one-third when considering transient loads due to wind
or seismic forces.
7.12 Preliminary Pavement Recommendations
7.12.1 We calculated the flexible pavement sections in general conformance with the Caltrans
Method of Flexible Pavement Design (Highway Design Manual, Section 608.4) using an
estimated Traffic Index (TI) of 5.0, 5.5, 6.0, and 7.0 for parking stalls, driveways, medium
truck traffic areas, and heavy truck traffic areas, respectively. The project civil engineer and
owner should review the pavement designations to determine appropriate locations for
pavement thickness. The final pavement sections for the parking lot should be based on the
R-Value of the subgrade soil encountered at final subgrade elevation. We used an R-Value of
20and 50 for the subgrade soil and an R-Value of 78 for aggregate base for the purposes of
this preliminary analysis. Table 7.12.1 presents the preliminary flexible pavement sections.
TABLE 7.12.1
PRELIMINARY FLEXIBLE PAVEMENT SECTION
Location
Assumed
Traffic
Index
Assumed
Subgrade
R-Value
Asphalt
Concrete
(inches)
Class 2
Aggregate
Base (inches)
Parking Stalls for Automobiles
and Light-Duty Vehicles 5.0 20 3 7
50 3 4
Driveways for Automobiles
and Light-Duty Vehicles 5.5 20 3 9
50 3 4
Medium Truck Traffic Areas 6.0 20 3.5 10
50 3.5 4
Driveways for Heavy Truck Traffic 7.0 20 4 12
50 4 5
Geocon Project No. G3112-52-01 - 25 - July 17, 2025
7.12.2 Prior to placing base materials, the upper 12 inches of the subgrade soil should be scarified,
moisture conditioned as necessary, and recompacted to a dry density of at least 95 percent of
the laboratory maximum dry density near to slightly above optimum moisture content as
determined by ASTM D 1557. Similarly, the base material should be compacted to a dry
density of at least 95 percent of the laboratory maximum dry density near to slightly above
optimum moisture content. Asphalt concrete should be compacted to a density of at least 95
percent of the laboratory Hveem density in accordance with ASTM D 2726.
7.12.3 Base materials should conform to Section 26-1.02B of the Standard Specifications for The
State of California Department of Transportation (Caltrans) with a ¾-inch maximum size
aggregate. Asphalt concrete should conform to Section 203-6 of the Standard Specifications
for Public Works Construction (Greenbook).
7.12.4 The base thickness can be reduced if a reinforcement geogrid is used during the installation
of the pavement. Geocon should be contact for additional recommendations if alternate design
parameters are requested.
7.12.5 A rigid Portland cement concrete (PCC) pavement section should be placed in roadway aprons
and cross gutters. We calculated the rigid pavement section in general conformance with the
procedure recommended by the American Concrete Institute report ACI 330-21 Commercial
Concrete Parking Lots and Site Paving Design and Construction – Guide. Table 7.13.2
provides the traffic categories and design parameters used for the calculations for 20-year
design life.
TABLE 7.12.2
TRAFFIC CATEGORIES
Traffic
Category Description Reliability
(%)
Slabs Cracked at End
of Design Life (%)
A Car Parking Areas and Access Lanes 60 15
B Entrance and Truck Service Lanes 60 15
E Garbage or Fire Truck Lane 75 15
7.12.6 We used the parameters presented in Table 7.12.3 to calculate the pavement design sections.
We should be contacted to provide updated design sections, if necessary.
Geocon Project No. G3112-52-01 - 26 - July 17, 2025
TABLE 7.12.3
RIGID PAVEMENT DESIGN PARAMETERS
Design Parameter Design Value
Modulus of Subgrade Reaction, k 100 pci
Modulus of Rupture for Concrete, MR 500 psi
Concrete Compressive Strength 3,000 psi
Concrete Modulus of Elasticity, E 3,150,000 psi
7.12.7 Based on the criteria presented herein, the PCC pavement sections should have a minimum
thickness as presented in Table 7.12.4.
TABLE 7.12.4
RIGID VEHICULAR PAVEMENT RECOMMENDATIONS
Traffic Category Trucks Per Day Portland Cement
Concrete, T (Inches)
A = Car Parking Areas and Access Lanes 10 5½
B = Entrance and Truck Service Lanes 10 6
E = Garbage or Fire Truck Lanes 5 6½
7.12.8 The PCC vehicular pavement should be placed over subgrade soil that is compacted to a dry
density of at least 95 percent of the laboratory maximum dry density near to slightly above
optimum moisture content. The garbage truck pad should be large enough such that all wheels
are on the concrete pad during the loading operations.
7.12.9 Adequate joint spacing should be incorporated into the design and construction of the rigid
pavement in accordance with Table 7.12.5.
TABLE 7.12.5
MAXIMUM JOINT SPACING
Pavement Thickness, T (Inches) Maximum Joint Spacing (Feet)
4<T<5 10
5<T<6 12.5
6<T 15
7.12.10 The rigid pavement should also be designed and constructed incorporating the parameters
presented in Table 7.12.6.
Geocon Project No. G3112-52-01 - 27 - July 17, 2025
TABLE 7.12.6
ADDITIONAL RIGID PAVEMENT RECOMMENDATIONS
Subject Value
Thickened Edge
1.2 Times Slab Thickness Adjacent to Structures
1.5 Times Slab Thickness Adjacent to Soil
Minimum Increase of 2 Inches
4 Feet Wide
Crack Control Joint
Depth
Early Entry Sawn = T/6 to T/5, 1.25 Inch Minimum
Conventional (Tooled or Conventional Sawing) = T/4 to T/3
Crack Control Joint
Width
¼-Inch for Sealed Joints and Per Sealer Manufacturer’s
Recommendations
1/16- to 1/4-Inch is Common for Unsealed Joints
7.12.11 Reinforcing steel will not be necessary within the concrete for geotechnical purposes with the
possible exception of dowels at construction joints as discussed herein.
7.12.12 To control the location and spread of concrete shrinkage cracks, crack-control joints
(weakened plane joints) should be included in the design of the concrete pavement slab.
Crack-control joints should be sealed with an appropriate sealant to prevent the migration of
water through the control joint to the subgrade materials. The depth of the crack-control joints
should be in accordance with the referenced ACI guide.
7.12.13 To provide load transfer between adjacent pavement slab sections, a butt-type construction
joint should be constructed. The butt-type joint should be thickened by at least 20 percent at
the edge and taper back at least 4 feet from the face of the slab.
7.12.14 Concrete curb/gutter should be placed on soil subgrade compacted to a dry density of at least
90 percent of the laboratory maximum dry density near to slightly above optimum moisture
content. Cross-gutters that receive vehicular traffic should be placed on subgrade soil
compacted to a dry density of at least 95 percent of the laboratory maximum dry density near
to slightly above optimum moisture content. Base materials should not be placed below the
curb/gutter, or cross-gutters so water is not able to migrate from the adjacent parkways to the
pavement sections. Where flatwork is located directly adjacent to the curb/gutter, the concrete
flatwork should be structurally connected to the curbs to help reduce the potential for offsets
between the curbs and the flatwork.
Geocon Project No. G3112-52-01 - 28 - July 17, 2025
7.13 Site Drainage and Moisture Protection
7.13.1 Adequate site drainage is critical to reduce the potential for differential soil movement,
erosion and subsurface seepage. Under no circumstances should water be allowed to pond
adjacent to footings. The site should be graded and maintained such that surface drainage is
directed away from structures in accordance with 2022 CBC 1804.4 or other applicable
standards. In addition, surface drainage should be directed away from the top of slopes into
swales or other controlled drainage devices. Roof and pavement drainage should be directed
into conduits that carry runoff away from the proposed structure.
7.13.2 In the case of basement walls or building walls retaining landscaping areas, a water-proofing
system should be used on the wall and joints, and a Miradrain drainage panel (or similar)
should be placed over the waterproofing. The project architect or civil engineer should
provide detailed specifications on the plans for all waterproofing and drainage.
7.13.3 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks and detected leaks should be repaired promptly. Detrimental soil
movement could occur if water is allowed to infiltrate the soil for prolonged periods of time.
7.13.4 Landscaping planters adjacent to paved areas are not recommended due to the potential for
surface or irrigation water to infiltrate the pavement's subgrade and base course. Area drains
to collect excess irrigation water and transmit it to drainage structures or impervious above-
grade planter boxes can be used. In addition, where landscaping is planned adjacent to the
pavement, construction of a cutoff wall along the edge of the pavement that extends at least 6
inches below the bottom of the base material should be considered.
7.13.5 We have prepared a storm water infiltration feasibility report under separate cover.
7.14 Grading and Foundation Plan Review
7.14.1 Geocon Incorporated should review the grading and building foundation plans for the project
prior to final design submittal to evaluate if additional analyses and/or recommendations are
required.
7.15 Testing and Observation Services During Construction
7.15.1 Geocon Incorporated should provide geotechnical testing and observation services during
the grading operations, foundation construction, utility installation, retaining wall backfill
and pavement installation. Table 7.15 presents the typical geotechnical observations we
would expect for the proposed improvements.
Geocon Project No. G3112-52-01 - 29 - July 17, 2025
TABLE 7.15
EXPECTED GEOTECHNICAL TESTING AND OBSERVATION SERVICES
Construction Phase Observations Expected Time Frame
Grading/Temporary
Excavations
Base of Removal Part Time During
Removals
Fill Placement and Soil Compaction Full Time
Foundations Foundation Excavation Observations Full Time
Utility Backfill Fill Placement and Soil Compaction Part Time to Full Time
Retaining Wall
Backfill/Subdrains Fill Placement and Soil Compaction Part Time to Full Time
Subgrade for Sidewalks,
Curb/Gutter and Pavement Soil Compaction Part Time
Pavement Construction
Base Placement and Compaction Part Time
Asphalt Concrete Placement and
Compaction Full Time
Geocon Project No. G3112-52-01 July 17, 2025
LIMITATIONS AND UNIFORMITY OF CONDITIONS
1. We prepared the geotechnical investigation for the project. We should be retained to provide
testing and observation services during construction to provide continuity of geotechnical
interpretation and to check that the recommendations presented for geotechnical aspects of site
development are incorporated during site grading, construction of improvements, and
excavation of foundations. If another geotechnical firm is selected to perform the testing and
observation services during construction operations, we should be notified and the selected firm
should prepare a letter indicating their intent to assume the responsibilities of project
geotechnical engineer of record. A copy of the letter should be provided to us and the regulatory
agency for their records. In addition, that firm should provide revised recommendations
concerning the geotechnical aspects of the proposed development, or a written
acknowledgement of their concurrence with the recommendations presented in our report. They
should also perform additional analyses deemed necessary to assume the role of Geotechnical
Engineer of Record.
2. The recommendations of this report pertain only to the site investigated and are based on the
assumption that the soil conditions do not deviate from those disclosed in the investigation. If
any variations or undesirable conditions are encountered during construction, or if the proposed
construction will differ from that anticipated herein, Geocon Incorporated should be notified to
provide additional recommendations. The evaluation or identification of the potential presence
of hazardous or corrosive materials was not part of the scope of services provided by Geocon
Incorporated.
3. This report is issued with the understanding that it is the responsibility of the owner or his
representative to ensure that the information and recommendations contained herein are brought
to the attention of the architect and engineer for the project and incorporated into the plans, and
the necessary steps are taken to see that the contractor and subcontractors carry out such
recommendations in the field.
4. The findings of this report are valid as of the present date. However, changes in the conditions
of a property can occur with the passage of time, whether they be due to natural processes or
the works of man on this or adjacent properties. In addition, changes in applicable or appropriate
guidelines/standards may occur, whether they result from legislation or the broadening of
knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by
changes outside our control. Therefore, this report is subject to review and should not be relied
upon after a period of three years.
DN
A3.1
1
A3.1 2
A3.0
2
A3.01
2
A4.0
A4.0
1
A4.2
1
A4.2
811 SF
Commercial Suite
101
589 SF
Commercial Suite
102
539 SF
Commercial Suite
103
591 SF
Commercial Suite
104
1071 SF
Commercial Suite
105 59 SF
W.C.
106
39 SF
W.C.
107
39 SF
W.C.
108
60 SF
Elevator
100
221 SF
Electrical Room
111
117 SF
Lobby
110
Open Parking
Property Line
Property Line
Property Line
Property Line
Public Street Easement Line
Utility Easement Line
Face of Curb
Gutter
8%
25 SF
ECR
109
Transformer
hand hole
USP
S
M
a
i
l
b
o
x
e
s
105.1 104.2 103.1 102.2 101.2 109
110.1
111.2
150
111
.
1
101.1
101.3102.1103.2104.1
105.2
106
107
108
A5.5S17
A5.5S2
A5.5
S5
A5.5
S6
A5.5
S8
A5.5
S11
A5.5
S13
104 SF
Hall
310-3
68 SF
MPOE
310-4
112 SF
Dry Storage
310-5
3
1a
2
2
2
1a
3
2
2
1a
1a
13a
13a
13b
1a
1a
1a
1a1a
4
1a
10b
1a
1a
1a
1a
1a
1a
13a
13b
13b
2
1a
10b
10b 10b
10b
10b13b
11
10b
13b
10a10b
10b
13b
13b
8a
8a8a8b8b
11
1a
55 6a
13a
13a
13a
2
13b
13b
1a
1a
13a
12
12
13b
13b
6b
6b
13b
1a
2
13a14
13a
13a
13a
1a
13a
1b
6c
1a
1a
1a
7
1c
3
A4.0
A4.0
1
A4.0
1
A4.1 1
A4.1
2
A4.2
2
A4.2
3
A4.1
3
A4.1
2
A4.1
2
A4.1
A5.5S1
A5.5
S3
A5.5
S4
A5.5
S7
A5.5
S9
A5.5
S10
A5.5
S12
A5.5
S14
A5.5
S15
A5.5 2
A6.281
ID706
1 1'
B-1
B-2
P-1
P-2
Qudf/ /
PROPOSED BUILDING
PAD: 40.65'
FF: 41.40'
2'
2'2'
3'
LINE OF PODIUM EDGE
ABOVE TYPICAL
LINE OF PODIUM EDGE
ABOVE TYPICAL
LINE OF PODIUM EDGE
ABOVE TYPICAL
GEOLOGIC MAP
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159PROJECT NO. G3112 - 52 - 01FIGURE 1 DATE 06 - 17 - 2025
GEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:07/07/2025 9:34AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G3112-52-01 2621 Roosevelt Street\SHEETS\G3112-52-01 GeoMap.dwg
B-2
GEOCON LEGEND
........APPROX. LOCATION OF EXPLORATORY BORING
........APPROX. LOCATION OF INFILTRATION TEST
........APPROX. LOCATION OF GEOLOGIC CROSS-SECTION
1 1'
........UNDOCUMENTED FILLQudf
........OLD PARALIC DEPOSITS (Dotted Where Buried)Qop
P-2
........SANTIAGO FORMATION (Dotted Where Buried)Tsa
........APPROX. DEPTH TO FORMATIONAL MATERIALS (In Feet)3'
BLOCK VALL
-,
'II
(\J st-
IG'II i.'DDD FENCE
1Gl1 CHAIN LINK F NCE
D
"-"-"-':::! f---BUILDING □VERH NG "-"-"-._. " PA KING LDT <1 :)_
"-
y
jl ,,----42-----_______ _
----------------47::=-..:---=
-----ll-.._..Lilf-s -il-------t s
PARK NG LDT
I = = c=; c=i
___ _/
DRIVEVAY
X
_j
\
\
\
c\,
i\
\
\
\
o' 20· 40'
s
+
D I
SCALE 1"= 20' (On 11x17)
GEOCON
INCORPORATED
■ ■
EL
E
V
A
T
I
O
N
(
M
S
L
)
EL
E
V
A
T
I
O
N
(
M
S
L
)
DISTANCE (FEET)
SCALE: 1" = 20' (Vert. = Horiz.)
GEOLOGIC CROSS-SECTION 1-1'
0
20
40
60
80
0
20
40
60
80
0 20 40 60 80 100 120 140 160 180 200
1 1'
B-1
Elevation=41'
(Proj. 48' SE)
N55ºE
EXISTING BUILDING
?
?
?
?
Qop
Tsa
Qudf ROOSEVELT
ST.
PROPOSED BUILDING
PAD: 40.65'
FF: 41.40'
B-2
Elevation=42'
(Proj. 64' SE)
Qudf Qudf
EXISTING
GRADE PROPOSED
GRADE
?········································································································································································································
????
2
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159PROJECT NO. G3112 - 52 - 01
GEOLOGIC CROSS - SECTION DATE 06 - 17 - 2025 FIGURE
GEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:07/07/2025 10:14AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G3112-52-01 2621 Roosevelt Street\SOURCE\SECTION\G3112-52-01 Profiles.dwg
B-2
GEOCON LEGEND
........APPROX. LOCATION OF EXPLORATORY BORING
........UNDOCUMENTED FILLQudf
........OLD PARALIC DEPOSITSQop
........APPROX. LOCATION OF GEOLOGIC CONTACT
(Queried Where Uncertain)
........SANTIAGO FORMATIONTsa
?
........PERCHED GROUNDWATER·············
-I I I I I I I I I I I I I I I I I I I I I I I I I I I I I t I I I I I I I I I I I I I I I I I I I I I I I I I I I I -
-~ I I I I I 1 t I I t I I I I I I t -~
-~
-~
-~
t ~il~ rt rh-h-h I rh-h-l ~ rtil:, ! ! -~
r I I I h-t -~
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l I I I ...
I f f l I t t f ( I I
I ( I 1 I ( t t
1• --------"""'!' "!""' --.J -C i.: L I -
ill 1™ JI~ r I !! I !! I I !I ll1J II II~ * I I "¥. bJ
-I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I • It T i I I I I I I -l l l l l l l l l l l l l l l l l l l l l l l l L l l l l l I 1 l l l I 1 l l l I 1 l l l l l l l l
II
l
r'J GEOCON
INCORPORAT E D
7 ■ ■
APPENDIX A
Geocon Project No. G3112-52-01 July 17, 2025
APPENDIX A
FIELD INVESTIGATION
We performed the exploratory operations on April 20, 2023 using a Mobile drill B-51 drill rig equipped
with hollow-stem augers with Native Drilling. Borings extended to maximum depth of approximately
20 feet. The infiltration-test borings were drilled to depths of approximately 5 to 6 feet.
The Geologic Map, Figure 1, presents the approximate locations of the exploratory excavations. This
appendix presents a summary of the boring logs. We located the exploratory excavations in the field
using a measuring tape and existing reference points; therefore, actual boring locations may deviate
slightly.
We obtained samples during our subsurface exploration in the borings using a California sampler that
is composed of steel and driven to obtain ring samples. The California sampler has an inside diameter
of 2.5 inches and an outside diameter of 3 inches. Up to 18 rings are placed inside the sampler that is
2.4 inches in diameter and 1 inch in height. We obtained soil samples at appropriate intervals, placed
them in moisture-tight containers, and transported them to the laboratory for testing. We also collected
bulk samples of the existing materials for laboratory testing. The type of sample is noted on the
exploratory boring logs.
The California sampler is connected to A rods and driven into the bottom of the excavation using a 140-
pound hammer with a 30-inch drop. We attempted to drive the California sampler a minimum of 12
inches. We record the blow counts for every 6 inches the sampler is driven. The penetration resistances
shown on the boring logs are shown in terms of blows per foot. The blow count values indicated on the
boring logs are the sum of the last 12 inches or the portion able to be driven. If the sampler was not
driven for 12 inches, an approximate value is calculated in term of blows per foot or the final interval is
reported. These values are not to be taken as N-values as adjustments have not been applied. We
estimated elevations shown on the boring logs either from a topographic map or by using a benchmark.
Each excavation was backfilled as noted on the boring logs.
We visually examined, classified, and logged the soil encountered in the borings in general accordance
with American Society for Testing and Materials (ASTM) practice for Description and Identification of
Soils (Visual-Manual Procedure D 2488). The logs depict the general soil and geologic conditions
observed and the depth at which we obtained soil samples.
6" ASPHALT CONCRETE
UNDOCUMENTED FILL (Qudf)
Medium dense, moist, reddish brown, Silty, fine to medium SAND
OLD PARALIC DEPOSITS (Qop)
Medium dense, damp to moist, reddish to yellowish brown, Silty, fine to
coarse SANDSTONE
-Difficult drilling
-Becomes moist to wet
-Perched groundwater between 11-13 feet, becomes pale brown
-Transition in sample
SANTIAGO FORMATION (Tsa)
Very dense, moist, light gray to white, Silty, fine to coarse SANDSTONE
BORING TERMINATED AT 20 FEET
Perched groundwater at 11 feet
100.2
117.4
109.6
117.8
119.6
7.9
8.1
8.8
13.6
11.9
B1-1
B1-2
B1-3
B1-4
B1-5
30
30
43
70/11"
90/11"
SM
SM
SM
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
8
10
12
14
16
18
20
Figure A-1,
Log of Boring B 1, Page 1 of 1
DR
Y
D
E
N
S
I
T
Y
(P
.
C
.
F
.
)
... DRIVE SAMPLE (UNDISTURBED)
MOBILE DRILL B-51 PE
N
E
T
R
A
T
I
O
N
RE
S
I
S
T
A
N
C
E
(B
L
O
W
S
/
F
T
.
)
BORING B 1
... CHUNK SAMPLE
DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOIL
CLASS
(USCS)
GR
O
U
N
D
W
A
T
E
R
N. GARCIA CO
N
T
E
N
T
(
%
)
SAMPLE
NO.04-20-2023
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)41'
G3112-52-01.GPJ
MATERIAL DESCRIPTION
LI
T
H
O
L
O
G
Y
... STANDARD PENETRATION TEST
... WATER TABLE OR ... SEEPAGE
NOTE:
PROJECT NO.
THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
G3112-52-01
,... -,... ----r-t-r flj ,... -
,... -I ::.j:·l .f·
I • ·~ · ,. ·t.
,... -: :t: J: :~: . ·1·.
,... -I ::~:i::t:
,... -. :t: 1: .f .
• J.·.·t·
,... -: ·t. j. :~:
: :~: 1: :t:
,... -: :t: J: :~:
,... -: :~: 1: :t:
•• j ••
,... -I : :t: 1: :~:
.J.·.·t· ,... -: ·t. j. :~:
,... -: :~: 1: :t:
: :t: J: :~: ,... -: :~: 1: :t:
,... -: :t: J: :~: . ·1·.
,... -I ·tj•:•t· : ·~ .. :r:
,... -I • ·~. ,. ·t.
: :t: J: :~:
,... -: :~: 1: :t:
,... -: :t: J: :~:
: :~: 1: :t: ,... -,... .. j ·. :-t•1·t ,... . . . .
'Sj_
I]
liiiiJ
■
_y
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
6" ASPHALT CONCRETE
UNDOCUMENTED FILL (Qudf)
Medium dense, moist, dark reddish brown, Silty, fine to coarse SAND
OLD PARALIC DEPOSITS (Qop)
Medium dense, moist, reddish to yellowish brown, Silty, fine to coarse
SANDSTONE
-Perched groundwater
-Becomes dense, wet
SANTIAGO FORMATION (Tsa)
Very dense, moist, light gray to white, Silty, fine to coarse SANDSTONE
BORING TERMINATED AT 20 FEET
Perched groundwater at 15 feet
112.5
110.8
121.9
120.1
7.2
8.4
15.0
11.7
B2-1
B2-2
B2-3
B2-4
B2-5
26
43
49
50/9"
SM
SM
SM
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
8
10
12
14
16
18
20
Figure A-2,
Log of Boring B 2, Page 1 of 1
DR
Y
D
E
N
S
I
T
Y
(P
.
C
.
F
.
)
... DRIVE SAMPLE (UNDISTURBED)
MOBILE DRILL B-51 PE
N
E
T
R
A
T
I
O
N
RE
S
I
S
T
A
N
C
E
(B
L
O
W
S
/
F
T
.
)
BORING B 2
... CHUNK SAMPLE
DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOIL
CLASS
(USCS)
GR
O
U
N
D
W
A
T
E
R
N. GARCIA CO
N
T
E
N
T
(
%
)
SAMPLE
NO.04-20-2023
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)42'
G3112-52-01.GPJ
MATERIAL DESCRIPTION
LI
T
H
O
L
O
G
Y
... STANDARD PENETRATION TEST
... WATER TABLE OR ... SEEPAGE
NOTE:
PROJECT NO.
THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
G3112-52-01
,... -,... ----r-t-r _::--.-_··.r: _::
,... -.--.l.·.r-1 • ·~. ,. ·t.
,... -: :t: J: :~:
: :~: 1: :t: ,... -: :t: J: :~:
,... -: :~: 1: :t:
,... -: :t: J: :~:
: :~: 1: :t: ,... -: :t: J: :~:
,... -: :~: 1: :t:
: :t: J: :~: ,... -: :~: 1: :t:
,... -I j :t: l: j~ j
,... -• :~: 1: ·t.
: :t: J: :~: ,... -: :~: 1: :t:
,... -: :t: J: :~:
: :~: 1: :t: ,... -: :t: J: :~:
,... -I : :~: 1: :t: 'Sj_
,... -: :t: J: :~: . ·1· .
,... -. J.j.•t· • ·~. ,. ·t.
,... -: :t: J: :~: . ·1·. ,... -I ::~:i::t:
,... · :t: 1: .f ·
I]
liiiiJ
■
_y
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
6" ASPHALT CONCRETE
UNDOCUMENTED FILL (Qudf)
Medium dense, moist, reddish brown, Silty, fine to coarse SAND
OLD PARALIC DEPOSITS (Qop)
Medium dense, damp to moist, reddish to yellowish brown, Silty, fine to
coarse SANDSTONE
BORING TERMINATED AT 6 FEET
No groundwater encountered
SM
SM
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
Figure A-3,
Log of Boring P 1, Page 1 of 1
DR
Y
D
E
N
S
I
T
Y
(P
.
C
.
F
.
)
... DRIVE SAMPLE (UNDISTURBED)
MOBILE DRILL B-51 PE
N
E
T
R
A
T
I
O
N
RE
S
I
S
T
A
N
C
E
(B
L
O
W
S
/
F
T
.
)
BORING P 1
... CHUNK SAMPLE
DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOIL
CLASS
(USCS)
GR
O
U
N
D
W
A
T
E
R
N. GARCIA CO
N
T
E
N
T
(
%
)
SAMPLE
NO.04-20-2023
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)41'
G3112-52-01.GPJ
MATERIAL DESCRIPTION
LI
T
H
O
L
O
G
Y
... STANDARD PENETRATION TEST
... WATER TABLE OR ... SEEPAGE
NOTE:
PROJECT NO.
THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
G3112-52-01
,... -,... ----r-t-r _::--.-_··.r: _::
,... -.--.l.·.r-1 • ·~. ,. ·t.
,... -: :t: J: :~:
: :~: 1: :t: ,... -: :t: J: :~:
,... -: :~: 1: :t:
,... : ·~. j. :r:
I]
liiiiJ
■
_y
-
-
-
-
6" ASPHALT CONCRETE
UNDOCUMENTED FILL (Qudf)
Medium dense, moist, reddish brown, Silty, fine to coarse SAND
OLD PARALIC DEPOSITS (Qop)
Medium dense, reddish to yellowish brown, Silty, fine to coarse
SANDSTONE
BORING TERMINATED AT 5 FEET
No groundwater encountered
SM
SM
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
Figure A-4,
Log of Boring P 2, Page 1 of 1
DR
Y
D
E
N
S
I
T
Y
(P
.
C
.
F
.
)
... DRIVE SAMPLE (UNDISTURBED)
MOBILE DRILL B-51 PE
N
E
T
R
A
T
I
O
N
RE
S
I
S
T
A
N
C
E
(B
L
O
W
S
/
F
T
.
)
BORING P 2
... CHUNK SAMPLE
DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOIL
CLASS
(USCS)
GR
O
U
N
D
W
A
T
E
R
N. GARCIA CO
N
T
E
N
T
(
%
)
SAMPLE
NO.04-20-2023
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)41'
G3112-52-01.GPJ
MATERIAL DESCRIPTION
LI
T
H
O
L
O
G
Y
... STANDARD PENETRATION TEST
... WATER TABLE OR ... SEEPAGE
NOTE:
PROJECT NO.
THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
G3112-52-01
,... -,... ----r-t-r _::--.-_··.r: _::
,... -.--.l.·.r-1 • ·~. ,. ·t.
,... -: :t: J: :~:
: :~: 1: :t: ,... -: :t•: J: :~:
,... • .. 1.·.·
I]
liiiiJ
■
_y
-
-
-
APPENDIX B
Geocon Project No. G3112-52-01 - B-1 - July 17, 2025
APPENDIX B
LABORATORY TESTING
We performed laboratory tests in accordance with generally accepted test methods of the American Society
for Testing and Materials (ASTM) or other suggested procedures. We tested selected soil samples for in-
place dry density/moisture content, maximum density/optimum moisture content, expansion index, water-
soluble sulfate, content, R-Value, hand penetrometer reading, consolidation, gradation and direct shear
strength. The results of our current laboratory tests are presented herein. The in-place dry density and
moisture content of the samples tested are presented on the boring logs in Appendix A.
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557
Sample
No. Description (Geologic Unit)
Maximum
Dry Density
(pcf)
Optimum
Moisture Content
(% dry wt.)
B2-1 Reddish brown, Silty, fine to coarse SAND (Qudf/Qop) 134.4 7.3
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS ASTM D 4829
Sample No.
Moisture Content (%) Dry
Density
(pcf)
Expansion
Index
2019 CBC
Expansion
Classification
ASTM Soil
Expansion
Classification Before
Test After Test
B2-1 7.3 12.7 119.9 0 Non-Expansive Very Low
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sample No. Depth (feet) Geologic Unit Water-Soluble
Sulfate (%)
ACI 318 Sulfate
Exposure
B2-1 0-5 Qudf/Qop 0.008 S0
SUMMARY OF LABORATORY RESISTANCE VALUE (R-VALUE) TEST RESULTS ASTM D 2844
Sample No. Depth (Feet) Description (Geologic Unit) R-Value
B2-1 0-5 Reddish brown, Silty, fine to coarse SAND (Qudf/Qop) 68
-----
Geocon Project No. G3112-52-01 - B-2 - July 17, 2025
SUMMARY OF LABORATORY HAND PENETROMETER READING TEST RESULTS ASTM D 1558 (WITHDRAWN)
Sample No. Depth (feet) Geologic Unit Hand Penetrometer Reading (ksf)
B1-1 5 Qop 4.5+
B1-3 15 Qop 4
B1-4 15 Qop/Tsa 4.5+
B1-5 20 Tsa 4.5+
B2-4 15 Qop 4.0
B2-5 20 Tsa 4.5+
SAMPLE NO.:Qop
SAMPLE DEPTH (FT):
B1-2
5'
GEOLOGIC UNIT:
TEST INFORMATION
117.4
PROJECT NO.: G3112-52-01
8.1%
INITIAL DRY DENSITY (PCF):
INITIAL WATER CONTENT (%):
SAMPLE SATURATED AT (KSF):
INITIAL SATURATION (%):
2.0
52.4%
CONSOLIDATION CURVE - ASTM D 2435
2621 ROOSEVELT STREET
‐2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.10 1.00 10.00
VE
R
T
I
C
A
L
ST
R
A
I
N
(%
)
APPLIED PRESSURE (KSF)
GEOCO
INCORPORATED
GEO TECHNICAL CONSULT ANTS
6960 FLANDERS DRIVE • SAN DIEGO, CALIFORNIA 92121 -297 4
PHONE 858 558-6900 -FAX 858 558-6159
........ ,
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........ ~ ........
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SAMPLE NO.:Qop
SAMPLE DEPTH (FT):
B2-3
10'
GEOLOGIC UNIT:
TEST INFORMATION
110.8
PROJECT NO.: G3112-52-01
8.4%
INITIAL DRY DENSITY (PCF):
INITIAL WATER CONTENT (%):
SAMPLE SATURATED AT (KSF):
INITIAL SATURATION (%):
2.0
44.9%
CONSOLIDATION CURVE - ASTM D 2435
2621 ROOSEVELT STREET
‐2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.10 1.00 10.00
VE
R
T
I
C
A
L
ST
R
A
I
N
(%
)
APPLIED PRESSURE (KSF)
GEOCO
INCORPORATED
GEO TECHNICAL CONSULT ANTS
6960 FLANDERS DRIVE • SAN DIEGO, CALIFORNIA 92121 -297 4
PHONE 858 558-6900 -FAX 858 558-6159
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SAMPLE NO.:GEOLOGIC UNIT:
SAMPLE DEPTH (FT):NATURAL/REMOLDED:
1 K 2 K 4 K AVERAGE
890 2030 4300 --
6.8 7.8 6.9 7.2
112.5 110.2 114.8 112.5
1 K 2 K 4 K AVERAGE
14.7 15.5 13.7 14.6
970 1624 3070 --
951 1624 3060 --
400
32
380
32
COHESION, C (PSF)
DRY DENSITY (PCF):
AFTER TEST CONDITIONS
B2-2
G3112-52-01
2621 ROOSEVELT STREET
COHESION, C (PSF)
FRICTION ANGLE (DEGREES)
DIRECT SHEAR - AASHTO T-236
PROJECT NO.:
FRICTION ANGLE (DEGREES)
NORMAL STRESS TEST LOAD
ACTUAL NORMAL STRESS (PSF):
WATER CONTENT (%):
ULTIMATE
RESULTS
PEAK
Qop
5'
NORMAL STRESS TEST LOAD
WATER CONTENT (%):
PEAK SHEAR STRESS (PSF):
ULT.-E.O.T. SHEAR STRESS (PSF):
INITIAL CONDITIONS
N
0
500
1000
1500
2000
2500
3000
3500
0.000 0.050 0.100 0.150 0.200 0.250 0.300
SH
E
A
R
ST
R
E
S
S
(P
S
F
)
HORIZONTAL DEFORMATION (IN)
1 K 2 K 4 K
1 K PEAK 2 K PEAK 4 K PEAK
1 K ULTIMATE 2 K ULTIMATE 4 K ULTIMATE
4 K
2 K
1K
0
1000
2000
3000
4000
5000
6000
7000
0 1000 2000 3000 4000 5000 6000
SH
E
A
R
ST
R
E
S
S
(P
S
F
)
NORMAL STRESS (PSF)A
X
A
X
GEOCON
INCORPORATED
GEOTECHNICAL CONSULT ANTS
A
X
6960 FLANDERS DRIVE • SAN DIEGO, CALIFORNIA 92121 ·2974
PHONE 858 558-6900 • FAX 858 558-6159
' ./
/
-------PEAK
ULTIMATE
✓ /
·-
/ /
r
Qop
D10 (mm) D30 (mm) D60 (mm)
0.00005 0.00329 0.00895
GEOLOGIC UNIT:
0-5'
B2-1
SAMPLE DEPTH (FT.):
SAMPLE NO.:
SIEVE ANALYSES - ASTM D 6913
2621 ROOSEVELT
PROJECT NO.:
Cc
23.5
Cu
174.1
G3112-52-01
SOIL DESCRIPTION
Silty SAND
TEST DATA
U.S. STANDARD SIEVE SIZE
3"2"1½
"
1 ¾"½"⅜"
#4 #8
#1
0
#1
6
#2
0
#3
0
#4
0
#5
0
#6
0
#8
0
#1
0
0
#2
0
0
0
10
20
30
40
50
60
70
80
90
100
0.0010.010.1110100
PE
R
C
E
N
T
P
A
S
S
I
N
G
PARTICLE SIZE (mm)
SILT OR CLAY
GRAVEL SAND
COARSEFINECOARSE MEDIUM FINE
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-----
GEOCON
INCORPORATED
GEOTECHNICAL CONSULT ANTS
6960 FLANDERS DRIVE • SAN DIEGO, CALIFORNIA 92121 -297 4
PHONE 858 558-6900 • FAX 858 558-6159
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APPENDIX C
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
FOR
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
PROJECT NO. G3112-52-01
GI rev. 07/2015
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
1.1 These Recommended Grading Specifications shall be used in conjunction with the
Geotechnical Report for the project prepared by Geocon. The recommendations contained
in the text of the Geotechnical Report are a part of the earthwork and grading specifications
and shall supersede the provisions contained hereinafter in the case of conflict.
1.2 Prior to the commencement of grading, a geotechnical consultant (Consultant) shall be
employed for the purpose of observing earthwork procedures and testing the fills for
substantial conformance with the recommendations of the Geotechnical Report and these
specifications. The Consultant should provide adequate testing and observation services so
that they may assess whether, in their opinion, the work was performed in substantial
conformance with these specifications. It shall be the responsibility of the Contractor to
assist the Consultant and keep them apprised of work schedules and changes so that
personnel may be scheduled accordingly.
1.3 It shall be the sole responsibility of the Contractor to provide adequate equipment and
methods to accomplish the work in accordance with applicable grading codes or agency
ordinances, these specifications and the approved grading plans. If, in the opinion of the
Consultant, unsatisfactory conditions such as questionable soil materials, poor moisture
condition, inadequate compaction, and/or adverse weather result in a quality of work not in
conformance with these specifications, the Consultant will be empowered to reject the
work and recommend to the Owner that grading be stopped until the unacceptable
conditions are corrected.
2. DEFINITIONS
2.1 Owner shall refer to the owner of the property or the entity on whose behalf the grading
work is being performed and who has contracted with the Contractor to have grading
performed.
2.2 Contractor shall refer to the Contractor performing the site grading work.
2.3 Civil Engineer or Engineer of Work shall refer to the California licensed Civil Engineer
or consulting firm responsible for preparation of the grading plans, surveying and verifying
as-graded topography.
2.4 Consultant shall refer to the soil engineering and engineering geology consulting firm
retained to provide geotechnical services for the project.
GI rev. 07/2015
2.5 Soil Engineer shall refer to a California licensed Civil Engineer retained by the Owner,
who is experienced in the practice of geotechnical engineering. The Soil Engineer shall be
responsible for having qualified representatives on-site to observe and test the Contractor's
work for conformance with these specifications.
2.6 Engineering Geologist shall refer to a California licensed Engineering Geologist retained
by the Owner to provide geologic observations and recommendations during the site
grading.
2.7 Geotechnical Report shall refer to a soil report (including all addenda) which may include
a geologic reconnaissance or geologic investigation that was prepared specifically for the
development of the project for which these Recommended Grading Specifications are
intended to apply.
3. MATERIALS
3.1 Materials for compacted fill shall consist of any soil excavated from the cut areas or
imported to the site that, in the opinion of the Consultant, is suitable for use in construction
of fills. In general, fill materials can be classified as soil fills, soil-rock fills or rock fills, as
defined below.
3.1.1 Soil fills are defined as fills containing no rocks or hard lumps greater than
12 inches in maximum dimension and containing at least 40 percent by weight of
material smaller than ¾ inch in size.
3.1.2 Soil-rock fills are defined as fills containing no rocks or hard lumps larger than
4 feet in maximum dimension and containing a sufficient matrix of soil fill to allow
for proper compaction of soil fill around the rock fragments or hard lumps as
specified in Paragraph 6.2. Oversize rock is defined as material greater than
12 inches.
3.1.3 Rock fills are defined as fills containing no rocks or hard lumps larger than 3 feet
in maximum dimension and containing little or no fines. Fines are defined as
material smaller than ¾ inch in maximum dimension. The quantity of fines shall be
less than approximately 20 percent of the rock fill quantity.
3.2 Material of a perishable, spongy, or otherwise unsuitable nature as determined by the
Consultant shall not be used in fills.
3.3 Materials used for fill, either imported or on-site, shall not contain hazardous materials as
defined by the California Code of Regulations, Title 22, Division 4, Chapter 30, Articles 9
GI rev. 07/2015
and 10; 40CFR; and any other applicable local, state or federal laws. The Consultant shall
not be responsible for the identification or analysis of the potential presence of hazardous
materials. However, if observations, odors or soil discoloration cause Consultant to suspect
the presence of hazardous materials, the Consultant may request from the Owner the
termination of grading operations within the affected area. Prior to resuming grading
operations, the Owner shall provide a written report to the Consultant indicating that the
suspected materials are not hazardous as defined by applicable laws and regulations.
3.4 The outer 15 feet of soil-rock fill slopes, measured horizontally, should be composed of
properly compacted soil fill materials approved by the Consultant. Rock fill may extend to
the slope face, provided that the slope is not steeper than 2:1 (horizontal:vertical) and a soil
layer no thicker than 12 inches is track-walked onto the face for landscaping purposes. This
procedure may be utilized provided it is acceptable to the governing agency, Owner and
Consultant.
3.5 Samples of soil materials to be used for fill should be tested in the laboratory by the
Consultant to determine the maximum density, optimum moisture content, and, where
appropriate, shear strength, expansion, and gradation characteristics of the soil.
3.6 During grading, soil or groundwater conditions other than those identified in the
Geotechnical Report may be encountered by the Contractor. The Consultant shall be
notified immediately to evaluate the significance of the unanticipated condition.
4. CLEARING AND PREPARING AREAS TO BE FILLED
4.1 Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of
complete removal above the ground surface of trees, stumps, brush, vegetation, man-made
structures, and similar debris. Grubbing shall consist of removal of stumps, roots, buried
logs and other unsuitable material and shall be performed in areas to be graded. Roots and
other projections exceeding 1½ inches in diameter shall be removed to a depth of 3 feet
below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to
provide suitable fill materials.
4.2 Asphalt pavement material removed during clearing operations should be properly
disposed at an approved off-site facility or in an acceptable area of the project evaluated by
Geocon and the property owner. Concrete fragments that are free of reinforcing steel may
be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3 of this
document.
GI rev. 07/2015
4.3 After clearing and grubbing of organic matter and other unsuitable material, loose or
porous soils shall be removed to the depth recommended in the Geotechnical Report. The
depth of removal and compaction should be observed and approved by a representative of
the Consultant. The exposed surface shall then be plowed or scarified to a minimum depth
of 6 inches and until the surface is free from uneven features that would tend to prevent
uniform compaction by the equipment to be used.
4.4 Where the slope ratio of the original ground is steeper than 5:1 (horizontal:vertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
Remove All
Unsuitable Material
As Recommended By
Consultant
Finish Grade Original Ground
Finish Slope Surface
Slope To Be Such That
Sloughing Or Sliding
Does Not Occur Varies
“B”
See Note 1
No Scale
See Note 2
1
2
DETAIL NOTES: (1) Key width "B" should be a minimum of 10 feet, or sufficiently wide to permit complete coverage with the compaction equipment used. The base of the key should be graded horizontal, or inclined slightly into the natural slope.
(2) The outside of the key should be below the topsoil or unsuitable surficial material and at least 2 feet into dense formational material. Where hard rock is exposed in the bottom of the key, the depth and configuration of the key may be modified as approved by the Consultant.
4.5 After areas to receive fill have been cleared and scarified, the surface should be moisture
conditioned to achieve the proper moisture content, and compacted as recommended in
Section 6 of these specifications.
---
....
.................... 1 I .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ....
-----
GI rev. 07/2015
5. COMPACTION EQUIPMENT
5.1 Compaction of soil or soil-rock fill shall be accomplished by sheepsfoot or segmented-steel
wheeled rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of
acceptable compaction equipment. Equipment shall be of such a design that it will be
capable of compacting the soil or soil-rock fill to the specified relative compaction at the
specified moisture content.
5.2 Compaction of rock fills shall be performed in accordance with Section 6.3.
6. PLACING, SPREADING AND COMPACTION OF FILL MATERIAL
6.1 Soil fill, as defined in Paragraph 3.1.1, shall be placed by the Contractor in accordance with
the following recommendations:
6.1.1 Soil fill shall be placed by the Contractor in layers that, when compacted, should
generally not exceed 8 inches. Each layer shall be spread evenly and shall be
thoroughly mixed during spreading to obtain uniformity of material and moisture
in each layer. The entire fill shall be constructed as a unit in nearly level lifts. Rock
materials greater than 12 inches in maximum dimension shall be placed in
accordance with Section 6.2 or 6.3 of these specifications.
6.1.2 In general, the soil fill shall be compacted at a moisture content at or above the
optimum moisture content as determined by ASTM D 1557.
6.1.3 When the moisture content of soil fill is below that specified by the Consultant,
water shall be added by the Contractor until the moisture content is in the range
specified.
6.1.4 When the moisture content of the soil fill is above the range specified by the
Consultant or too wet to achieve proper compaction, the soil fill shall be aerated by
the Contractor by blading/mixing, or other satisfactory methods until the moisture
content is within the range specified.
6.1.5 After each layer has been placed, mixed, and spread evenly, it shall be thoroughly
compacted by the Contractor to a relative compaction of at least 90 percent.
Relative compaction is defined as the ratio (expressed in percent) of the in-place
dry density of the compacted fill to the maximum laboratory dry density as
determined in accordance with ASTM D 1557. Compaction shall be continuous
over the entire area, and compaction equipment shall make sufficient passes so that
the specified minimum relative compaction has been achieved throughout the
entire fill.
GI rev. 07/2015
6.1.6 Where practical, soils having an Expansion Index greater than 50 should be placed
at least 3 feet below finish pad grade and should be compacted at a moisture
content generally 2 to 4 percent greater than the optimum moisture content for the
material.
6.1.7 Properly compacted soil fill shall extend to the design surface of fill slopes. To
achieve proper compaction, it is recommended that fill slopes be over-built by at
least 3 feet and then cut to the design grade. This procedure is considered
preferable to track-walking of slopes, as described in the following paragraph.
6.1.8 As an alternative to over-building of slopes, slope faces may be back-rolled with a
heavy-duty loaded sheepsfoot or vibratory roller at maximum 4-foot fill height
intervals. Upon completion, slopes should then be track-walked with a D-8 dozer
or similar equipment, such that a dozer track covers all slope surfaces at least
twice.
6.2 Soil-rock fill, as defined in Paragraph 3.1.2, shall be placed by the Contractor in accordance
with the following recommendations:
6.2.1 Rocks larger than 12 inches but less than 4 feet in maximum dimension may be
incorporated into the compacted soil fill, but shall be limited to the area measured
15 feet minimum horizontally from the slope face and 5 feet below finish grade or
3 feet below the deepest utility, whichever is deeper.
6.2.2 Rocks or rock fragments up to 4 feet in maximum dimension may either be
individually placed or placed in windrows. Under certain conditions, rocks or rock
fragments up to 10 feet in maximum dimension may be placed using similar
methods. The acceptability of placing rock materials greater than 4 feet in
maximum dimension shall be evaluated during grading as specific cases arise and
shall be approved by the Consultant prior to placement.
6.2.3 For individual placement, sufficient space shall be provided between rocks to allow
for passage of compaction equipment.
6.2.4 For windrow placement, the rocks should be placed in trenches excavated in
properly compacted soil fill. Trenches should be approximately 5 feet wide and
4 feet deep in maximum dimension. The voids around and beneath rocks should be
filled with approved granular soil having a Sand Equivalent of 30 or greater and
should be compacted by flooding. Windrows may also be placed utilizing an
"open-face" method in lieu of the trench procedure, however, this method should
first be approved by the Consultant.
GI rev. 07/2015
6.2.5 Windrows should generally be parallel to each other and may be placed either
parallel to or perpendicular to the face of the slope depending on the site geometry.
The minimum horizontal spacing for windrows shall be 12 feet center-to-center
with a 5-foot stagger or offset from lower courses to next overlying course. The
minimum vertical spacing between windrow courses shall be 2 feet from the top of
a lower windrow to the bottom of the next higher windrow.
6.2.6 Rock placement, fill placement and flooding of approved granular soil in the
windrows should be continuously observed by the Consultant.
6.3 Rock fills, as defined in Section 3.1.3, shall be placed by the Contractor in accordance with
the following recommendations:
6.3.1 The base of the rock fill shall be placed on a sloping surface (minimum slope of 2
percent). The surface shall slope toward suitable subdrainage outlet facilities. The
rock fills shall be provided with subdrains during construction so that a hydrostatic
pressure buildup does not develop. The subdrains shall be permanently connected
to controlled drainage facilities to control post-construction infiltration of water.
6.3.2 Rock fills shall be placed in lifts not exceeding 3 feet. Placement shall be by rock
trucks traversing previously placed lifts and dumping at the edge of the currently
placed lift. Spreading of the rock fill shall be by dozer to facilitate seating of the
rock. The rock fill shall be watered heavily during placement. Watering shall
consist of water trucks traversing in front of the current rock lift face and spraying
water continuously during rock placement. Compaction equipment with
compactive energy comparable to or greater than that of a 20-ton steel vibratory
roller or other compaction equipment providing suitable energy to achieve the
required compaction or deflection as recommended in Paragraph 6.3.3 shall be
utilized. The number of passes to be made should be determined as described in
Paragraph 6.3.3. Once a rock fill lift has been covered with soil fill, no additional
rock fill lifts will be permitted over the soil fill.
6.3.3 Plate bearing tests, in accordance with ASTM D 1196, may be performed in both
the compacted soil fill and in the rock fill to aid in determining the required
minimum number of passes of the compaction equipment. If performed, a
minimum of three plate bearing tests should be performed in the properly
compacted soil fill (minimum relative compaction of 90 percent). Plate bearing
tests shall then be performed on areas of rock fill having two passes, four passes
and six passes of the compaction equipment, respectively. The number of passes
required for the rock fill shall be determined by comparing the results of the plate
bearing tests for the soil fill and the rock fill and by evaluating the deflection
GI rev. 07/2015
variation with number of passes. The required number of passes of the compaction
equipment will be performed as necessary until the plate bearing deflections are
equal to or less than that determined for the properly compacted soil fill. In no case
will the required number of passes be less than two.
6.3.4 A representative of the Consultant should be present during rock fill operations to
observe that the minimum number of “passes” have been obtained, that water is
being properly applied and that specified procedures are being followed. The actual
number of plate bearing tests will be determined by the Consultant during grading.
6.3.5 Test pits shall be excavated by the Contractor so that the Consultant can state that,
in their opinion, sufficient water is present and that voids between large rocks are
properly filled with smaller rock material. In-place density testing will not be
required in the rock fills.
6.3.6 To reduce the potential for “piping” of fines into the rock fill from overlying soil
fill material, a 2-foot layer of graded filter material shall be placed above the
uppermost lift of rock fill. The need to place graded filter material below the rock
should be determined by the Consultant prior to commencing grading. The
gradation of the graded filter material will be determined at the time the rock fill is
being excavated. Materials typical of the rock fill should be submitted to the
Consultant in a timely manner, to allow design of the graded filter prior to the
commencement of rock fill placement.
6.3.7 Rock fill placement should be continuously observed during placement by the
Consultant.
7. SUBDRAINS
7.1 The geologic units on the site may have permeability characteristics and/or fracture
systems that could be susceptible under certain conditions to seepage. The use of canyon
subdrains may be necessary to mitigate the potential for adverse impacts associated with
seepage conditions. Canyon subdrains with lengths in excess of 500 feet or extensions of
existing offsite subdrains should use 8-inch-diameter pipes. Canyon subdrains less than 500
feet in length should use 6-inch-diameter pipes.
GI rev. 07/2015
TYPICAL CANYON DRAIN DETAIL
7.2 Slope drains within stability fill keyways should use 4-inch-diameter (or lager) pipes.
........................
NATURAi.GROUND ,,,,,,-----
.................
............ ........
.................. __ --
SEE DETAL BELOW
NOTES:
1 ...... 8-lNCH DIAMETER, SCHEDULE 80 PVC PERFORATED PIPE FOR FILLS
IN EXCESS OF 100-FEET IN DEPTH ORA PIPE LENGTH OF LONGER THAN 500 FEET.
2 ...... 6-INCH DIAMETER, SCHEDULE 40 PVC PERFORATED PIPE FOR FILLS
LESS THAN 100-FEET IN DEPTH OR A PIPE LENGTH SHORTER THAN 500 FEET.
,, ------,-
.,,,.,,,,,,,.,,,..
BEDROCK
NOTE: FINAL 20' OF PIPEAT CUTI.ET
SHALL BE NON-PERFORATED.
9 CUBIC FEET/ FOOT OF OPEN
GRADED GRAVEL SURROUNDED BY
MIRAF1 140NC (OR EQUIVALENT)
FILTER FABRIC
NO SCALE
GI rev. 07/2015
TYPICAL STABILITY FILL DETAIL
7.3 The actual subdrain locations will be evaluated in the field during the remedial grading
operations. Additional drains may be necessary depending on the conditions observed and
the requirements of the local regulatory agencies. Appropriate subdrain outlets should be
evaluated prior to finalizing 40-scale grading plans.
7.4 Rock fill or soil-rock fill areas may require subdrains along their down-slope perimeters to
mitigate the potential for buildup of water from construction or landscape irrigation. The
subdrains should be at least 6-inch-diameter pipes encapsulated in gravel and filter fabric.
Rock fill drains should be constructed using the same requirements as canyon subdrains.
DETAIL
NOTES:
FORMAnONAL
MATERIAL
1 ..... EXCAVATE BACKCUT AT 1:1 INCUNATION (UNLESS OTHERWISE NOTl:D~
2 .... .BASE OF STABILITY FILL TO BE 3 FEET INTO FORMATIONAL MATERIAL, SI.OPING A MINIMUM 5% INTO SLOPE.
3 ..... STABIUTY FLL TO BE COMF'OSED OF PROPERLY COMPACTED GRANIA..AR SOIL
4 ..... CHIMNEY DRAINS TO BE APPROVED PREFABRICATED CHIMNEY DRAIN PANELS (MIRADRAIN G200N OR EQUIVALENT)
SPACED AF'PROXIMATELY 20 FEET CENTER TO CENTER AND 4 FEETWIDE. CLOSER SPACING MAY BE REQUIRED F
SEEPAGE IS ENCOUNTERED.
5 ..... FILTER MATERIAL TO BE 314-tlCH, OPEN-GRADED CRUSI-IED ROCK ENCLOSED IN APPROVED FL TER FABRIC (MIRAFI 1-40NC~
6 ..... COLLECTOR PIPE TO BE 4-INCH MINIMUM DIAMETER, PERFORATED, THICK-WALLED PVC SCHEDULE 40 OR
EQUIVALENT, AND SLOPED TO DRAIN AT 1 PERCENT lilNMUM TO APPROVED oun.ET.
NO SCALE
GI rev. 07/2015
7.5 Prior to outletting, the final 20-foot segment of a subdrain that will not be extended during
future development should consist of non-perforated drainpipe. At the non-perforated/
perforated interface, a seepage cutoff wall should be constructed on the downslope side of
the pipe.
TYPICAL CUT OFF WALL DETAIL
7.6 Subdrains that discharge into a natural drainage course or open space area should be
provided with a permanent headwall structure.
FRONT VIEW
SIDE VIEW
'
CONCRETE
CUT-OFF WAU.
CONCRETE
CUT-OFFWAU.
SOLID SlJBDRAII P1PE
',( /
8' MIN.
NO SCALE
ll" MIN.(TYP)
ll" MIN.(TYP) /
NO SCALE
GI rev. 07/2015
TYPICAL HEADWALL DETAIL
7.7 The final grading plans should show the location of the proposed subdrains. After
completion of remedial excavations and subdrain installation, the project civil engineer
should survey the drain locations and prepare an “as-built” map showing the drain
locations. The final outlet and connection locations should be determined during grading
operations. Subdrains that will be extended on adjacent projects after grading can be placed
on formational material and a vertical riser should be placed at the end of the subdrain. The
grading contractor should consider videoing the subdrains shortly after burial to check
proper installation and functionality. The contractor is responsible for the performance of
the drains.
FRONT VIEW
SIDE VIEW
8"0R8"
SUBDRAIN
CONCRETE
fEADWALL
8" ORB"
SUBDRAIN
~ 24"
NOTE: HEADWALL SHOULD ounET AT TOE OF FILL SLOPE
OR INTO CONTROLLED SURFACE DRAINAGE
NO SCALE
12"
NO SCALE
GI rev. 07/2015
8. OBSERVATION AND TESTING
8.1 The Consultant shall be the Owner’s representative to observe and perform tests during
clearing, grubbing, filling, and compaction operations. In general, no more than 2 feet in
vertical elevation of soil or soil-rock fill should be placed without at least one field density
test being performed within that interval. In addition, a minimum of one field density test
should be performed for every 2,000 cubic yards of soil or soil-rock fill placed and
compacted.
8.2 The Consultant should perform a sufficient distribution of field density tests of the
compacted soil or soil-rock fill to provide a basis for expressing an opinion whether the fill
material is compacted as specified. Density tests shall be performed in the compacted
materials below any disturbed surface. When these tests indicate that the density of any
layer of fill or portion thereof is below that specified, the particular layer or areas
represented by the test shall be reworked until the specified density has been achieved.
8.3 During placement of rock fill, the Consultant should observe that the minimum number of
passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant
should request the excavation of observation pits and may perform plate bearing tests on
the placed rock fills. The observation pits will be excavated to provide a basis for
expressing an opinion as to whether the rock fill is properly seated and sufficient moisture
has been applied to the material. When observations indicate that a layer of rock fill or any
portion thereof is below that specified, the affected layer or area shall be reworked until the
rock fill has been adequately seated and sufficient moisture applied.
8.4 A settlement monitoring program designed by the Consultant may be conducted in areas of
rock fill placement. The specific design of the monitoring program shall be as
recommended in the Conclusions and Recommendations section of the project
Geotechnical Report or in the final report of testing and observation services performed
during grading.
8.5 We should observe the placement of subdrains, to check that the drainage devices have
been placed and constructed in substantial conformance with project specifications.
8.6 Testing procedures shall conform to the following Standards as appropriate:
8.6.1 Soil and Soil-Rock Fills:
8.6.1.1 Field Density Test, ASTM D 1556, Density of Soil In-Place By the
Sand-Cone Method.
GI rev. 07/2015
8.6.1.2 Field Density Test, Nuclear Method, ASTM D 6938, Density of Soil and
Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).
8.6.1.3 Laboratory Compaction Test, ASTM D 1557, Moisture-Density
Relations of Soils and Soil-Aggregate Mixtures Using 10-Pound
Hammer and 18-Inch Drop.
8.6.1.4. Expansion Index Test, ASTM D 4829, Expansion Index Test.
9. PROTECTION OF WORK
9.1 During construction, the Contractor shall properly grade all excavated surfaces to provide
positive drainage and prevent ponding of water. Drainage of surface water shall be
controlled to avoid damage to adjoining properties or to finished work on the site. The
Contractor shall take remedial measures to prevent erosion of freshly graded areas until
such time as permanent drainage and erosion control features have been installed. Areas
subjected to erosion or sedimentation shall be properly prepared in accordance with the
Specifications prior to placing additional fill or structures.
9.2 After completion of grading as observed and tested by the Consultant, no further
excavation or filling shall be conducted except in conjunction with the services of the
Consultant.
10. CERTIFICATIONS AND FINAL REPORTS
10.1 Upon completion of the work, Contractor shall furnish Owner a certification by the Civil
Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of
elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot
horizontally of the positions shown on the grading plans. After installation of a section of
subdrain, the project Civil Engineer should survey its location and prepare an as-built plan
of the subdrain location. The project Civil Engineer should verify the proper outlet for the
subdrains and the Contractor should ensure that the drain system is free of obstructions.
10.2 The Owner is responsible for furnishing a final as-graded soil and geologic report
satisfactory to the appropriate governing or accepting agencies. The as-graded report
should be prepared and signed by a California licensed Civil Engineer experienced in
geotechnical engineering and by a California Certified Engineering Geologist, indicating
that the geotechnical aspects of the grading were performed in substantial conformance
with the Specifications or approved changes to the Specifications.
Geocon Project No. G3112-52-01 July 17, 2025
LIST OF REFERENCES
1.2022 California Building Code, California Code of Regulations, Title 24, Part 2, based on the
2021 International Building Code, prepared by California Building Standards Commission,
dated July 2019.
2.ACI 318-19, Commentary on Building Code Requirements for Structural Concrete, prepared by
the American Concrete Institute, dated May, 2021.
3.ACI 330-21, Commercial Concrete Parking Lots and Site Paving Design and Construction,
prepared by the American Concrete Institute, dated May, 2021.
4.American Society of Civil Engineers (ASCE), ASCE 7-16, Minimum Design Loads and
Associated Criteria for Buildings and Other Structures, 2017.
5.California Department of Conservation, Division of Mines and Geology, Probabilistic Seismic
Hazard Assessment for the State of California, Open File Report 96-08, 1996.
6.California Geological Survey, Seismic Shaking Hazards in California, Based on the USGS/CGS
Probabilistic Seismic Hazards Assessment (PSHA) Model, 2002 (revised April 2003). 10%
probability of being exceeded in 50 years.
http://redirect.conservation.ca.gov/cgs/rghm/pshamap/pshamain.html
7.County of San Diego, San Diego County Multi Jurisdiction Hazard Mitigation Plan, San Diego,
California – Final Draft, dated 2017.
8.Historical Aerial Photos. http://www.historicaerials.com
9.Jennings, C. W., 1994, California Division of Mines and Geology, Fault Activity Map of
California and Adjacent Areas, California Geologic Data Map Series Map No. 6.
10.Kennedy, M. P., and S. S. Tan, 2007, Geologic Map of the Oceanside 30’x60’ Quadrangle,
California, USGS Regional Map Series Map No. 2, Scale 1:100,000.
11.Special Publication 117A, Guidelines For Evaluating and Mitigating Seismic Hazards in
California 2008, California Geological Survey, Revised and Re-adopted September 11, 2008.
12.Unpublished reports, aerial photographs, and maps on file with Geocon Incorporated.
13.USGS computer program, Seismic Hazard Curves and Uniform Hazard Response Spectra,
http://geohazards.usgs.gov/designmaps/us/application.php.
6960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone (858) 558-6900 ■ www.geoconinc.com
Project No. G3112-52-01
July 17, 2025
Fabric Investments
2727 Roosevelt Street, Suite B
Carlsbad, California 92008
Attention: Mr. Brandan Foote
Subject: RESPONSE TO REVIEW COMMENTS (GEOTECHNICAL REVIEW)
THE ROOSEVELT MIXED USE
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
Dear Mr. Foote:
We prepared this letter to address the referenced City of Carlsbad Geotechnical Report review
comments for the development of the subject project. Pertinent plans and reports are listed in the List
of References at the end of this letter. The pertinent review comments are listed herein with the
responses immediately following.
Comment 1:The report was prepared several years ago and indicates that it was prepared
without the benefit of plans for the development. Consequently, please review the
most current grading and building plans for the proposed project and provide any
additional geotechnical recommendations or modifications to the geotechnical
report as necessary to address the currently proposed development.
Response: Geocon has prepared an Update Geotechnical Investigation report to address
current development plans. Based on our review of the referenced grading and
building plans and the information contained within the referenced update
geotechnical report, we opine the plans and details have been prepared in
substantial conformance with the recommendations presented in the referenced
Update Geotechnical Investigation (updated to incorporate current plans).
Additional recommendations are not considered necessary at this time. We limited
our review to geotechnical aspects of project development and the review did not
include other details on the referenced structural plans or plan set. Geocon
Incorporated has no opinion regarding other details found on the referenced plans
that do not directly pertain to geotechnical aspects of site development.
Comment 2:Please provide a description of the most current proposed development and discuss
the proposed types of structures and improvements, proposed grading (depths and
GEOCON
INCORPORATED
CAL ■ E NV I RONMENTA L ■ MA T ER I A L S G E OT E CHN I
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 2 - July 17, 2025
limits of cut/fill necessary to establish proposed grades), type of foundations and
floors for the proposed structures and improvements, and locations and heights of
any proposed fence/retaining walls.
Response: We have provided an updated description of the project in Section 2 of the
referenced Update Geotechnical Investigation.
Comment 3:Please provide an updated Geologic Map utilizing the most current revision of the
grading plan for the project as the base map and at a sufficiently large scale to
clearly show (at a minimum): a) existing site topography and improvements, b)
proposed structures and improvements, c) proposed finished grades, d) geologic
units, and e) the locations of the subsurface exploration.
Response: Please see the Geologic Map, Figure 1 in the referenced report.
Comment 4:Please update Geologic Cross-Section 1-1’ as necessary based on the updated
Geologic Map requested in comment #3 above. Please add to the section to also
show a) the limits and finish grades of the proposed building, parking area, and
improvements associated with the proposed development.
Response: Please see Cross-Section 1-1’, Figure 2, in the referenced report.
Comment 5:The “Faults in Southern California” map provided in the report appears to show only
faults located generally south of Del Mar and no offshore faults. Please provide a
regional fault map that shows relevant faults within the Carlsbad/north county
region and offshore (Newport-Inglewood/Rose Canyon, Coronado Bank, San Diego
Trough, Elsinore, etc.).
Response: Please see Section 6.1 of the referenced report.
Comment 6:Please discuss local and regional faulting associated with the subject site. Please
include the names, distances, and potential magnitudes of faults potentially
impacting the subject property. Please include a discussion (and distance/direction
from the site) addressing the offshore segment of the Newport-Inglewood/Rose
Canyon fault as it relates to the subject site.
Response: The site is located in a coastal plain environment within the southern portion of the
Peninsular Ranges Geomorphic Province of southern California. The coastal plains
is a relatively stable block that is dissected by relatively few faults consisting of the
potentially the active Rose Canyon Fault Zone (west of site) and the Elsinore Fault
Zone (east of site) that is associated with and sub-parallel to the San Andreas Fault
Zone, which is the plate boundary between the Pacific and North American Plates.
A review of the referenced geologic materials and our knowledge of the general
area indicate that the site is not underlain by active, potentially active or inactive
faults. An active fault is defined by the California Geological Survey (CGS) as a fault
~GEOCON
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 3 - July 17, 2025
showing evidence for activity within the last 11,000 years. The site is not located
within a State of California Earthquake Fault Zone.
According to the computer program EZ-FRISK (Version 7.65), 10 known active faults
are located within a search radius of 50 miles from the property. We used the 2008
USGS fault database that provides several models and combinations of fault data
to evaluate the fault information. Based on this database, the nearest known active
faults are the Newport-Inglewood/Rose Canyon Fault system, located
approximately 5 miles west of the site and is the dominant source of potential
ground motion. Earthquakes that might occur on this fault system or other faults
within the southern California and northern Baja California area are potential
generators of significant ground motion at the site. The estimated deterministic
maximum earthquake magnitude and peak ground acceleration for the Newport-
Inglewood Fault are 7.5 and 0.40g, respectively. The estimated deterministic
maximum earthquake magnitude and peak ground acceleration for the Rose
Canyon Fault are 6.9 and 0.32g, respectively. The table below shows the estimated
maximum earthquake magnitude and peak ground acceleration for these and other
faults in relationship to the site location. We used acceleration attenuation
relationships developed by Boore-Atkinson (2008) NGA USGS2008, Campbell-
Bozorgnia (2008) NGA USGS, and Chiou-Youngs (2007) NGA USGS2008
acceleration-attenuation relationships in our analysis.
DETERMINISTIC SPECTRA SITE PARAMETERS
Fault Name
Approximate
Distance
from Site
(miles)
Direction
from Site
Maximum
Earthquake
Magnitude
(Mw)
Peak Ground Acceleration
Boore-
Atkins
on
2008
(g)
Campbell-
Bozorgnia
2008 (g)
Chiou-
Youngs
2007
(g)
Newport-Inglewood 5 West 7.5 0.33 0.33 0.40
Rose Canyon 5 West 6.9 0.27 0.29 0.32
Coronado Bank 21 West 7.4 0.15 0.11 0.13
Palos Verdes
Connected 21 West 7.7 0.17 0.12 0.15
Elsinore 23 East 7.9 0.26 0.21 0.29
Palos Verdes 34 North-
west 7.3 0.10 0.07 0.08
San Joaquin Hills 36 North 7.1 0.09 0.09 0.08
Earthquake Valley 44 South-
east 6.8 0.06 0.05 0.04
Chino 47 North 6.8 0.06 0.05 0.04
San Jacinto 47 East 7.9 0.10 0.07 0.09
~GEOCON
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 4 - July 17, 2025
It is our opinion the site could be subjected to moderate to severe ground shaking
in the event of an earthquake along any of the faults listed on the table above or
other faults in the southern California/ northern Baja California region. We do not
consider the site to possess a greater risk than that of the surrounding
developments.
Comment 7:The lab test result of the on-site soil provided in the report indicates an Expansion
Index of 0. However, Table 7.1 (Summary of Conclusions and Recommendations)
and Table 7.8.1 (Minimum Concrete Slab-On-Grade Recommendations) along with
other sections of the report indicate the use of soils with an Expansion Index of 50
or less are suitable for the proposed development. As soils with an Expansion Index
over 20 are considered expansive and require mitigation in accordance with
Sections 1803.5.3 and 1808.6 of the 2022 California Building Code, please clarify the
recommendations that are being provided for the design of the foundation/floor
slab of the proposed building to address soils with an EI between 20 and 50 and
satisfy the requirements of Section 1808.6 of the 2022 California Building Code.
Please provide the methods (1806.1 through 1806.4) and any geotechnical
parameters (Effective Plasticity Index, etc.) that are being recommended by Geocon,
Inc., to address expansive soils (for soils with an EI between 20 and 50) and satisfy
the requirements of Section 1808.6 of the 2022 California Building Code for the
proposed slab-on-ground construction; and provide a statement that the
foundation system for the proposed structure will meet the requirements of Section
1808.6 of the 2022 California Building Code. Please provide the basis for all
parameters provided.
Response: As indicated in our referenced report, our foundation and slab-on-grade
recommendations are intended to reduce the potential for cracking of slabs due to
expansive soil, differential settlement of existing soil or soil with varying
thicknesses. We do not consider the use of post-tensioned foundations necessary
for the existing site conditions, assuming the recommendations provided in our
report are incorporated into the design and construction of the project.
Comment 8:If the option provided in the report for the use of deepened footings (extending
through the fill and into Old Paralic Deposits) is chosen by the development team,
please clarify the minimum depth that the footings should extend into the Old
Paralic deposits.
Response: The minimum embedment into formation material is 6 inches, as indicated in Table
7.7 in the referenced report.
Comment 9:Please provide the Cal-OSHA Type Soil (A, B, or C) and associated temporary slope
inclination (H:V) that the construction plans and contractors should adhere to
during the design and construction of the development.
Response: It is the responsibility of the contractor and their competent person to ensure all
excavations, temporary slopes and trenches are properly constructed and
maintained in accordance with applicable OSHA guidelines in order to maintain
~GEOCON
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 5 - July 17, 2025
safety and the stability of the excavations and adjacent improvements. The OSHA
Soil Type would need to be determined by the contractor based on materials
encountered within the excavations during construction. Therefore, we are not
able to provide a generalized Soil Type classification for the site based on the results
of our field investigation. See section 7.5 in the referenced report for more
information.
Comment 10:Please clarify the recommendations for temporary cuts anticipated for this specific
project for the proposed remedial grading and/or foundation excavations along the
property boundaries. Please provide specific recommendations for excavations as
necessary to prevent adverse impact to the existing adjacent off-site property and
structures/improvements with respect to temporary cuts associated with the
proposed grading/construction along the property boundaries.
Response: The design team has elected to embed the building foundations into formational
materials; therefore, we expect the removals/temporary cuts would not exceed 3
feet for the remedial grading for the subject property.
Comment 11:Please evaluate and discuss the potential for storm water infiltration at the subject
site as part of the proposed project.
Response: We prepared a separate storm water report under separate cover and should be
submitted by the design team to the City for review.
Comment 12:Please add temporary excavations and retaining wall subdrains to the list of
geotechnical testing and observation services that should be performed during the
construction of this project.
Response: Table 7.15 of our referenced report has been updated to include temporary
excavations and retaining wall subdrains.
Should you have any questions regarding this correspondence, or if we may be of further service,
please contact the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Nikolas Garcia, EIT
Senior Staff Engineer
Matt Love
GE 3238
NG:ML:am
(e-mail) Addressee
~GEOCON
•
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 6 - July 17, 2025
LIST OF REFERENCES
1.Update Geotechnical Investigation, 2621 Roosevelt Street, Carlsbad California, Carlsbad,
California, prepared by Geocon Incorporated, dated July ??, 2025 (Project No. G3112-52-01).
2.Grading Plans for: The Roosevelt Mixed Use, 2621 Roosevelt Street, Carlsbad, California,
prepared by SWS Engineering, Inc., dated March 18, 2025.
3.Geotechnical Report Review, Land Development Engineering, 1635 Faraday Avenue, Carlsbad,
CA (City of Carlsbad), dated May 27, 2025 (Project ID: SDP2024-0001).
4. Risk Engineering, EZFRISK, 2015.
5. California Geologic Survey, State of California Earthquake Fault Zones, Point Loma Quadrangle,
May 1, 2003.
6. California Geologic Survey (2008), Special Publication 117, Guidelines For Evaluating and
Mitigating Seismic Hazards in California, Revised and Re-adopted September 11.
7. Campbell, K. W., and Y. Bozorgnia, NGA Ground Motion Model for the Geometric Mean
Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for
Periods Ranging from 0.01 to 10 s, Preprint of version submitted for publication in the NGA
Special Volume of Earthquake Spectra, Volume 24, Issue 1, pages 139-171, February 2008.
~GEOCON
6960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone (858) 558-6900 ■ www.geoconinc.com
Project No. G3112-52-01
September 19, 2025
Fabric Investments
2727 Roosevelt Street, Suite B
Carlsbad, California 92008
Attention: Mr. Brandan Foote
Subject: RESPONSE TO REVIEW COMMENTS (2nd GEOTECHNICAL REVIEW)
THE ROOSEVELT MIXED USE
2621 ROOSEVELT STREET
CARLSBAD, CALIFORNIA
Dear Mr. Foote:
We prepared this letter to address the referenced City of Carlsbad Geotechnical Report review
comments for the development of the subject project. Pertinent plans and reports are listed in the List
of References at the end of this letter. The pertinent review comments are listed herein with the
responses immediately following.
Comment 1:The lab test result of the on-site soil provided in the report indicates an Expansion
Index of 0. However, Table 7.1 (Summary of Conclusions and Recommendations)
and Table 7.8.1 (Minimum Concrete Slab-On-Grade Recommendations) along with
other sections of the report indicate the use of soils with an Expansion Index of 50
or less are suitable for the proposed development. As soils with an Expansion Index
over 20 are considered expansive and require mitigation in accordance with
Sections 1803.5.3 and 1808.6 of the 2022 California Building Code, please clarify the
recommendations that are being provided for the design of the foundation/floor
slab of the proposed building to address soils with an EI between 20 and 50 and
satisfy the requirements of Section 1808.6 of the 2022 California Building Code.
Please provide the methods (1806.1 through 1806.4) and any geotechnical
parameters (Effective Plasticity Index, etc.) that are being recommended by Geocon,
Inc., to address expansive soils (for soils with an EI between 20 and 50) and satisfy
the requirements of Section 1808.6 of the 2022 California Building Code for the
proposed slab-on-ground construction; and provide a statement that the
foundation system for the proposed structure will meet the requirements of Section
1808.6 of the 2022 California Building Code. Please provide the basis for all
parameters provided.(repeat comment – As the report provides
recommendations for the use of soils that are considered expansive per the 2022
California Building Code (EI greater than 20), please state the specific procedure
GEOCON
INCORPORATED
CAL ■ E NV I RONMENTA L ■ MA T ER I A L S G E OT E CHN I
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 2 - September 19, 2025
of Section 1808.6 of the 2022 CBC that is being applied for the foundation/slab
on-ground recommendations for the proposed structure to accommodate an
expansion index up to 50 (low) and satisfy the building code requirement and
mitigate potential expansive soils. Please provide a statement that the
geotechnical recommendations provided by the consultant in the geotechnical
report satisfy the requirements of Section 1808.6 of the 2022 California Building
Code.
Response: As indicated in our referenced report, our foundation and slab-on-grade
recommendations consider the anticipated soils that may be at ultimate grade and
are typical industry standard recommendations that are intended to reduce the
potential for cracking of slabs due to expansive soil, differential settlement of
existing soil or soil with varying thicknesses. We do not consider the use of post-
tensioned foundations necessary for the existing site conditions, assuming the
recommendations provided in our report are incorporated into the design and
construction of the project. Section 1808.6.2 of the CBC permits the structural
engineer to analyze and design such slabs by other methods than the two
referenced above.
Comment 2:Please provide the Cal-OSHA Type Soil (A, B, or C) and associated temporary slope
inclination (H:V) that the construction plans and contractors should adhere to
during the design and construction of the development. (repeat comment – as the
consultant has deferred to OSHA guidelines and the contractor for temporary
slopes/backcuts in the “Response to Review Comments…” report, please provide the
preliminary OSHA Type Soil (A, B, or C) based on the consultants subsurface
exploration and geotechnical knowledge of the subject site that the construction
plans and contractors should adhere to during the design and construction of the
development.)
Response: In general conformance with Occupation Safety and Health Act (OSHA) Trenching
and Excavation Safety, the site soils may be considered Soil Type B based on the
materials encountered during our referenced geotechnical investigation. The soil
type should be revised to Soil Type C if seepage is encountered along the face of
excavations. However, in accordance with OSHA, it is the responsibility of the
contractor and their competent person to determine the soil type during
construction to ensure all excavations, temporary slopes and trenches are properly
constructed and maintained in accordance with applicable OSHA guidelines, in
order to maintain safety and the stability of the excavations and adjacent
improvements. The Soil Type should be adjusted as necessary based on the
conditions observed in the field.
Comment 3:Please clarify the recommendations for temporary cuts anticipated for this specific
project for the proposed remedial grading and/or foundation excavations along the
property boundaries. Please provide specific recommendations for excavations as
necessary to prevent adverse impact to the existing adjacent off-site property and
structures/improvements with respect to temporary cuts associated with the
proposed grading/construction along the property boundaries.(repeat comment)
~GEOCON
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 3 - September 19, 2025
Response: A slot-cutting grading technique may be required where excavations are planned
adjacent to existing structures and improvements. Care should be taken by the
grading contractor so that impact to existing improvements and buildings does not
occur during slot-cut excavations. This may require reduce slot cut lengths if loose
or otherwise unstable soil is encountered. The contractor should be aware that
there is an inherent risk to slot-cutting as movement of near vertical excavations
can cause stress relief features and vertical ground settlement outside of the
excavation. The grading contractor should be prepared to take necessary steps to
provide lateral stability/temporary buttressing if slot cut sidewalls experience
instability. The slot-cutting should be perform using the A-B-C Method (excavate
the soil and place compacted fill in the A Areas, then the B areas, then the C areas).
The slot cuts should not exceed 10 feet wide.
Slot-Cutting Overexcavation Detail
Alternatively, the lateral limits of grading for the building pad can be reduced from
10 feet to 2 feet, where necessary, to limit the potential for undermining of
adjacent structure foundations.
Comment 4:Please add temporary excavations and retaining wall subdrains to the list of
geotechnical testing and observation services that should be performed during the
construction of this project.(repeat comment – the requested tasks have been
added to the “Construction Phase” column and not the “Observations” column of
Table 7.15 of the submitted updated report; please add to the “observations”
column.)
Response: Table 7.15 of has been updated and is presented below.
~GEOCON
PLAN VIEW
CROSS-SECTION
EXISTING GRADE
A r B
TEMPORARY
1:1 SLOPE
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 4 - September 19, 2025
TABLE 7.15
EXPECTED GEOTECHNICAL TESTING AND OBSERVATION SERVICES
Construction Phase Observations Expected Time Frame
Grading Base of Removal and Temporary Excavations Part Time During Removals
Fill Placement and Soil Compaction Full Time
Foundations Foundation Excavation Observations Full Time
Utility Backfill Fill Placement and Soil Compaction Part Time to Full Time
Retaining Wall Backfill Fill Placement, Soil Compaction and Subdrains Part Time to Full Time
Subgrade for Sidewalks,
Curb/Gutter and Pavement Soil Compaction Part Time
Pavement Construction Base Placement and Compaction Part Time
Asphalt Concrete Placement and Compaction Full Time
Should you have any questions regarding this correspondence, or if we may be of further service,
please contact the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Nikolas Garcia, EIT
Senior Staff Engineer
Matt Love
GE 3238
NG:ML:kv
(e-mail) Addressee
~GEOCON
-
The Roosevelt – Mixed Use
Response to Review Comments
Project No. G3112-52-01 - 5 - September 19, 2025
LIST OF REFERENCES
1.Update Geotechnical Investigation, 2621 Roosevelt Street, Carlsbad California, Carlsbad,
California, prepared by Geocon Incorporated, dated July 17, 2025 (Project No. G3112-52-01).
2.Grading Plans for: The Roosevelt Mixed Use, 2621 Roosevelt Street, Carlsbad, California,
prepared by SWS Engineering, Inc., dated March 18, 2025.
3.Geotechnical Report Review (2nd), Land Development Engineering, 1635 Faraday Avenue,
Carlsbad, CA (City of Carlsbad), dated August 19, 2025 (Project ID: SDP2024-0001).
~GEOCON