HomeMy WebLinkAboutPD 2023-0006; LA COSTA CANYON HIGH SCHOOL FITNESS CENTER; GEOTECHNICAL INVESTIGATION FOR LA COSTA CANYON HIGH SCHOOL FITNESS CENTER; 2022-10-03GEOTECHNICAL INVESTIGATION
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
PREPARED FOR
SAN DIEGUITO UNION HIGH SCHOOL DISTRICT
ENCINITAS, CALIFORNIA
OCTOBER 3, 2022, 2022
PROJECT NO. G1999-42-09B
Project No. G1999-42-09B
October 3, 2022
San Dieguito Union High School District
North Vulcan Avenue
Encinitas, California 92024
Attention: Mr. Daniel Young
Subject: LIMITED GEOTECHNICAL INVESTIGATION
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
Dear Mr. Young:
In accordance with your authorization of our proposal (LG-22332, dated June 20, 2022) we herein
submit the results of our limited geotechnical investigation for the subject site. The accompanying
report presents the findings and conclusions from our study. Based on the results of our study, it is our
opinion that the Fitness Center project can be developed as proposed, provided the recommendations
of this report are followed. This report has been prepared in accordance with the requirements of CGS
Note for submittal to the Division of State Architect (DSA).
If you have any questions regarding this investigation, or if we may be of further service, please contact
the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Raul R. Garcia
GE 2842
Garry W. Cannon
CEG 2201
RCE 56468
RRG:GWC:am
(e-mail) Addressee
(e-mail) Mr. Daniel Rodriguez
(e-mail) RNT Architects
Attention: Mr. Joe Mansfield
GEOCON
INCORPORATED
G E OT E CHN I CAL ■E NV I RONMENTA L ■ MA T ER I A L S
6960 Flanders Drive ■ Son Diego, California 92121-297 4 ■ Telephone 858.558.6900 ■ Fax 858.558.6159
TABLE OF CONTENTS
1.PURPOSE AND SCOPE ................................................................................................................. 1
2.SITE AND PROJECT DESCRIPTION ........................................................................................... 1
3.SOIL AND GEOLOGIC CONDITIONS ........................................................................................ 2
3.1 Undocumented Fill Soils (Qudf) ........................................................................................... 2
3.2 Santiago Formation (Tsa) ...................................................................................................... 2
4.GROUNDWATER .......................................................................................................................... 2
5 GEOLOGIC HAZARDS ................................................................................................................. 3
5.1 Regional Faulting................................................................................................................... 3
5.2 Local Faulting ........................................................................................................................ 3
5.3 Seismicity .............................................................................................................................. 3
5.4 Liquefaction and Seismically Induced Settlement ................................................................. 3
5.5 Landslides .............................................................................................................................. 3
5.6 Subsidence ............................................................................................................................. 3
5.7 Seiche and Tsunami ............................................................................................................... 4
5.8 Flooding ................................................................................................................................. 4
5.9 Expansive Soil ....................................................................................................................... 4
5.10 Hydro-compression................................................................................................................ 4
5.11 Erosion ................................................................................................................................... 4
5.12 Naturally Occurring Asbestos ................................................................................................ 4
6.CONCLUSIONS .............................................................................................................................. 5
6.1 General ................................................................................................................................... 5
6.2 Excavation and Soil Characteristics ...................................................................................... 6
6.3 Grading .................................................................................................................................. 7
6.4 Temporary Excavations ......................................................................................................... 8
6.5 Slopes ..................................................................................................................................... 9
6.6 Site-Specific Ground Motion Hazard Analysis ..................................................................... 9
6.7 Probabilistic Seismic Hazard Analysis .................................................................................. 9
6.8 Site-Specific Response Spectrum ........................................................................................ 10
6.9 Mapped Acceleration Parameters ........................................................................................ 10
6.10 Site-Specific Seismic Design Criteria.................................................................................. 11
6.11 Site-Specific Peak Ground Acceleration ............................................................................. 12
6.12 Shallow Foundations ........................................................................................................... 12
6.13 Concrete Slabs On Grade ..................................................................................................... 14
6.14 Exterior Concrete Flatwork ................................................................................................. 16
6.15 Retaining Walls ................................................................................................................... 17
6.16 Lateral Loading .................................................................................................................... 20
6.17 Pavement Recommendations ............................................................................................... 21
6.18 Site Drainage and Moisture Protection ................................................................................ 21
6.19 Geotechnical Engineer of Record ........................................................................................ 21
LIMITATIONS AND UNIFORMITY OF CONDITIONS
TABLE OF CONTENTS (Concluded)
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Site Plan/Geologic Map
Figures 3 and 4, Geologic Cross Section A-A′ and B-B′
Figure 5, Regional Geologic Map
Figure 6, Regional Fault Map
Figure 6A, Regional Geologic Map Explanation
Figure 7, Regional Seismicity Map
Figure 8, MCE Probabilistic Response Spectrum
Figures 9 and 10, Site Specific Design Earthquake Response Spectrum
APPENDIX A
FIELD INVESTIGATION
Figures A-1 – A-4, Logs of Borings
APPENDIX B
LABORATORY TESTING
Table B-I, Summary of Laboratory Direct Shear Test Results
Table B-II, Summary of Laboratory Expansion Index Test Results
Table B-III, Summary of Laboratory pH and Minimum Resistivity Test Results
Table B-IV, Summary of Laboratory Water Soluble Sulfate Content Test Results
Table B-V, Summary of Laboratory Chloride Ion Content Test Results
Table B-VI, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content Test Results
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
LIST OF REFERENCES
Geocon Project No. G1999-42-09B - 1 - October 3, 2022
GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the results of our geotechnical investigation for the proposed Fitness Center on the
campus of La Costa Canyon High School in the San Dieguito Union High School District of Carlsbad,
California (see Vicinity Map, Figure 1).
The purpose of the investigation was to identify the site geology; to observe and sample the prevailing
soil conditions underlying the areas planned to receive the new Fitness Center; and based on conditions
encountered, provide geotechnical recommendations for the design and construction of the foundation
system for the proposed development.
The scope of our investigation included a site reconnaissance, field investigation, laboratory testing, and
preparation of this report.
The field investigation was performed on August 11, 2022 and consisted of drilling four, small-diameter,
exploratory borings at the approximate locations depicted on the Site Plan/Geologic Map (Figure 2).
The logs of the exploratory borings and other details of the field investigation are presented in
Appendix A.
Laboratory tests were performed on selected soil samples obtained from the borings to assess pertinent
physical properties for engineering analyses. A discussion of the laboratory testing program and results
is presented in Appendix B.
The recommendations presented herein are based on our analysis of the data obtained from the
exploratory borings, laboratory tests, and our experience with similar soil and geologic conditions.
2. SITE AND PROJECT DESCRIPTION
La Costa Canyon High School is located at the southeast terminus of Maverick Way in Carlsbad,
California. The area planned to receive the Fitness Center is presently occupied by basketball courts,
located west of the existing Gymnasium Building and south of the student drop-off cul-de-sac (site
coordinates: latitude 33.072759, longitude -117.232217). Review of the grading plan prepared by RNT
Architects, indicates that the new Fitness Center will consist of two 2-story, rectangular, buildings with
an open area and a basketball court in between.
We expect the Fitness Center buildings will be concrete masonry unit (CMU) block structures with
concrete slab-on-grade supported by a shallow foundation system.
Geocon Project No. G1999-42-09B - 2 - October 3, 2022
Review of grading plans indicate that cuts and fills of less than 3 feet are proposed to achieve proposed
grade elevations. Considering that the existing site is relatively flat, minor grading consisting of the
removal and export of the undocumented clayey fill soil and the partial removal and export of the clayey
soil of the Santiago Formation should be expected. Imported soil with low expansion properties should
be anticipated as part of the grading operations.
The descriptions contained herein are based on our site reconnaissance and review of the previously
referenced documents. If project details vary significantly from those described, Geocon Incorporated
should be notified prior to submittal for review and possible revision of the recommendations presented
below.
3. SOIL AND GEOLOGIC CONDITIONS
We encountered undocumented fill the Santiago Formation during our field investigation. Site geologic
conditions are shown on the Site Plan/Geologic Map (Figure 2) and the Geologic Cross Sections A-A′
and B-B′, Figures 3 and 4, respectively. A description of the undocumented fill and Santiago Formation
is provided below.
3.1 Undocumented Fill Soils (Qudf)
Undocumented fill soils was encountered at the southwest corner of the site at a depth of 4 feet in the
vicinity of exploratory boring B-3. The undocumented fill is generally characterized as stiff, very moist
sandy clay. The undocumented fill is not suitable in its present condition and remedial grading in the
form of removal and exporting of the clayey soil will be required as described in the Grading Section of
this report.
3.2 Santiago Formation (Tsa)
Santiago Formation (Kennedy & Tan, 2007) was encountered underlying the undocumented fill soils in
exploratory Borings B-3 and at grade in exploratory borings B-1, B-2 and B-4. The Santiago Formation
is characterized as very stiff to hard, damp to very moist, olive gray, silty clay and dense to very dense,
moist to very moist, light olive brown, silty sand. The Santiago Formation will provide suitable support
for compacted fill and structural improvements. However, the clayey soil of the Santiago Formation
exhibits a high expansion potential and remedial grading in the form of partial removal and export as
indicated in the Grading Section of this report should be performed.
4. GROUNDWATER
Permanent groundwater was not encountered during the field investigation. Seepage was encountered
at a depth of 12 feet in boring B-1. Groundwater is not expected to significantly affect project
development as presently proposed. It is not uncommon for groundwater or seepage conditions to
Geocon Project No. G1999-42-09B - 3 - October 3, 2022
develop where none previously existed. Proper surface drainage of irrigation and rainwater will be
important to future performance of the project.
5 GEOLOGIC HAZARDS
5.1 Regional Faulting
Regional geologic information required to satisfy California Geological Survey (CGS) requirements for
geology and seismology reports for California Public Schools is presented on Figures 5 through 7. Figure
5 is regional fault map. Figure 6 is a regional geologic map. Figure 6A is regional geologic map
explanation. Figure 7 is a seismicity map that depicts the historic seismicity with respect to the site.
5.2 Local Faulting
No evidence of faulting was observed during our field investigation. The USGS (2016) and Kennedy &
Tan (2007) show that there are no mapped Quaternary faults crossing or trending toward the property.
The site is not located within a currently established Alquist-Priolo Earthquake Fault Zone (CGS,
2021a). No active faults are known to exist at the site. The risk associated with ground rupture hazard is
low.
5.3 Seismicity
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. The risk associated
with strong ground motion due to earthquake at the site is no greater than that for the region.
5.4 Liquefaction and Seismically Induced Settlement
Due to the dense nature of the Santiago Formation, the risk associated with seismically induced soil
liquefaction hazard is low.
5.5 Landslides
No evidence of landsliding was encountered at the site during the geotechnical investigation. Kennedy
& Tan (2007) do not show any mapped landslides at the site or in areas that would impact the site. The
risk associated with ground movement hazard due to landslide is low.
5.6 Subsidence
Based on the subsurface soil conditions encountered during our geotechnical investigation, the risk
associated with ground subsidence hazard is low.
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5.7 Seiche and Tsunami
The site is not located within a tsunami inundation zone as defined by CGS (2021b). There are no lakes
or reservoirs located near the site. The risk associated with inundation hazard due to tsunami or seiche
is low.
5.8 Flooding
The site is not located within a drainage or floodplain and is designated a Zone X (FEMA, 2019). The
risk associated with flooding hazard is low.
5.9 Expansive Soil
Based on the results of our laboratory testing, the on-site surficial soils are expansive. (expansion
index higher than 20).
5.10 Hydro-compression
The potential for hydro-compression in the underlying soils is low due to the relatively dense nature of
the formational bedrock soils.
5.11 Erosion
The site is not located adjacent to the Pacific Ocean coast or a free-flowing drainage where active
erosion is occurring. We do not expect erosion to impact to site development. In addition, we expect
the proposed development would not increase the potential for erosion if properly designed.
5.12 Naturally Occurring Asbestos
The geologic units and existing undocumented fill are not conducive for the presence of naturally
occurring asbestos. Therefore, the risk associated with naturally occurring asbestos hazard is low.
Geocon Project No. G1999-42-09B - 5 - October 3, 2022
6. CONCLUSIONS
6.1 General
6.1.1 From a geotechnical standpoint, it is our opinion that the site is suitable for the proposed
development, provided the recommendations presented herein are implemented in design and
construction of the project.
6.1.2 The southwest corner of the project site is underlain by approximately 4 feet of undocumented
fill that is compressible and will require removal and replacement with compacted low
expansive fill. The Santiago Formation underlies the undocumented fill and is near existing
grade in other areas of the site.
6.1.3 The undocumented fill and the clayey soil of the Santiago Formation underlying the area
planned to receive the Fitness Center exhibit a high expansion potential. Expansive clay soils
should be removed and exported from the site in accordance with the recommendations
indicated in the Grading Section of this report.
6.1.4 Sandy soil of the Santiago Formation should provide adequate foundation support for the
project.
6.1.5 Groundwater was not encountered in borings drilled during our field investigation. Seepage
was encountered at a depth of 12 feet in exploratory boring B-1. Groundwater is not expected
to significantly affect project development as presently proposed.
6.1.6 It is anticipated that the existing basketball courts, in the area planned to receive the new
Fitness Center will be renovated as part of project development.
6.1.7 Subsurface conditions observed in our borings are expected to be consistent across the site;
however, some variation in subsurface conditions between boring locations should be
anticipated.
6.1.8 No significant geologic hazards were observed or are known to exist on the site or other
locations that would adversely affect the proposed project.
6.1.9 Review of grading plans existing indicates that cuts and fills of less than 3 feet will be
performed to achieve proposed grade elevations.
Geocon Project No. G1999-42-09B - 6 - October 3, 2022
6.2 Excavation and Soil Characteristics
6.2.1 Excavation of the on-site soils should be possible with moderate to heavy effort using
conventional heavy-duty equipment.
6.2.2 The soil encountered in the field investigation are considered to be “expansive” (expansion
index [EI] higher than 20) as defined by 2019 California Building Code (CBC)
Section 1803.5.3 in accordance with ASTM D 4829. The following table presents soil
classifications based on the expansion index.
EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (EI) ASTM D 4829 Expansion
Classification
2019 CBC Expansion
Classification
0 – 20 Very Low Non-Expansive
21 – 50 Low
Expansive 51 – 90 Medium
91 – 130 High
Greater Than 130 Very High
6.2.3 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” and “S2” sulfate exposure to concrete structures as defined by 2019 CBC
Section 1904 and ACI 318-14 Chapter 19. The following table presents a summary of concrete
requirements set forth by 2019 CBC Section 1904 and ACI 318.Based on ACI guidelines,
concrete in contact with soil that possess “S2” classification should use Type V Cement, have
a maximum water ratio of 0.45, and have a compressive strength of 4,500 psi. The presence
of water-soluble sulfates is not a visually discernible characteristic; therefore, other soil
samples from the site could yield different concentrations. Additionally, over time
landscaping activities (i.e., addition of fertilizers and other soil nutrients) may affect the
concentration.
Geocon Project No. G1999-42-09B - 7 - October 3, 2022
REQUIREMENTS FOR CONCRETE EXPOSED TO
SULFATE-CONTAINING SOLUTIONS
Sulfate Severity Exposure Class
Water-Soluble Sulfate (SO4) Percent by Weight
Cement Type (ASTM C 150)
Maximum Water to Cement Ratioby Weight1
Minimum Compressive Strength (psi)
Not Applicable S0 SO4<0.10 No Type Restriction n/a 2,500
Moderate S1 0.10<SO4<0.20 II 0.50 4,000
Severe S2 0.20<SO4<2.00 V 0.45 4,500
Very Severe S3 SO4>2.00 V+Pozzolan or Slag 0.45 4,500
1 Maximum water to cement ratio limits do not apply to lightweight concrete
6.2.4 We tested samples for water-soluble, chloride content, pH and minimum resistivity to aid in
evaluating the soil corrosion potential to subsurface metal structures. Based on the test results,
the site soils possess a moderate to high corrosion potential to ferrous metals. Appendix B
presents the laboratory test results. Geocon Incorporated does not practice in the field of
corrosion engineering. Therefore, further evaluation by a corrosion engineer may be needed
if improvements susceptible to corrosion are planned.
6.3 Grading
6.3.1 Grading should be performed in accordance with the recommendations provided in this report,
the Recommended Grading Specifications contained in Appendix C and the applicable
agency’s grading ordinance. Geocon Incorporated should observe the grading operations on
a full-time basis and provide testing during the fill placement.
6.3.2 Prior to commencing grading, a preconstruction conference should be held at the site with the
project architect, DSA inspector of record, city inspector, 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.
6.3.3 Site preparation should begin with the demolition of existing structures and 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 site demolition should be exported from the site.
6.3.4 Abandoned utilities should be removed and the resultant depressions and/or trenches
backfilled with properly compacted soil as part of the remedial grading.
Geocon Project No. G1999-42-09B - 8 - October 3, 2022
6.3.5 Undocumented fill should be completely removed within proposed buildings pad and
associated improvements. Based on field investigation, we expect removals on the order of 4
feet will be required. Additionally, highly expansive clayey soils within the Santiago
Formation should be removed to a depth of 4 feet below existing and/or proposed grade,
whichever is deeper. To reduce the potential for differential settlement, the area underlying
by sandy soils of The Santiago Formation should be undercut 4 feet. The excavated sandy
soils can re-used and placed back as compacted fill. The removal should extend to at least 5
feet beyond the perimeter of the buildings and associated improvements (where practical).
6.3.6 Areas planned to receive fill should be scarified, moisture conditioned, and compacted to at
least 90 percent of the maximum dry density as determined by ASTM D1557. Import fill soils
should be placed in 8-inch-thick loose layers, moisture conditioned to slightly above optimum
moisture content and compacted to at least 90 percent of the dry density per ASTM D 1557,
until proposed grade elevation is achieved.
6.3.7 Geocon Incorporated should observe the remedial grading process to identify potential areas
where unsuitable soils are exposed. The actual depth of removal should be evaluated by the
geotechnical engineer during grading operations.
6.3.8 Imported fill should consist of the characteristics presented in the following table. 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.
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
6.4 Temporary Excavations
6.4.1 The recommendations included herein are provided for stable excavations. It is the
contractor’s responsibility to ensure that 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 or closer than 15 feet
Geocon Project No. G1999-42-09B - 9 - October 3, 2022
from an existing surface improvement should be shored in accordance with applicable OSHA
codes and regulations.
6.4.2 The stability of the excavations is dependent on the design and construction of the shoring
system and site conditions. Geocon Incorporated is not responsible for site safety and the
stability of the proposed excavations.
6.5 Slopes
6.5.1 No significant cut and fill slopes are proposed as part of project development.
6.5.2 Providing and maintaining proper surface drainage is imperative to assure soil stability and
reduce erosion. Finish grades should be constructed so surface runoff is directed away from
structures and the top of slopes to controlled drainage facilities. Water should not be allowed
to flow over the tops of slopes.
6.6 Site-Specific Ground Motion Hazard Analysis
6.6.1 A site-specific ground motion hazard analysis was performed in accordance with ASCE 7-
16 Chapter 21 and Section 1613A of the 2019 CBC using the online applications developed
by USGS.
6.7 Probabilistic Seismic Hazard Analysis
6.7.1 The risk-targeted Maximum Considered Earthquake (MCER) probabilistic response spectrum
consists of the spectral response accelerations which are expected to achieve a 1 percent
probability of collapse within a 50-year period, evaluated at 5 percent damping.
6.7.2 The median spectral response accelerations having a 2 percent chance of exceedance in 50
years were evaluated at 5 percent damping using the USGS Unified Hazard Tool (UHT). The
Dynamic U.S. 2014 (v4.2.0) edition was used within the analysis, which is based on the
UCERF-3 fault model. The soil underlying the site was modeled as a Site Class “C” with a
corresponding average shear wave velocity (VS30) of 537 meters per second. The site class
determination is based on Standard Penetration Test blow count data.
6.7.3 The web application uses the ground motion prediction equations (GMPEs) from the NGA-
West 2 project: Abrahamson-et al. (2014) NGA West 2, Boore et al. (2014) NGA West 2,
Campbell-Bozorgnia (2014) NGA West 2, and Chiou-Youngs (2014) NGA West 2. Each
GMPE was assigned an equal weight and the median value of the four GMPEs was evaluated.
Geocon Project No. G1999-42-09B - 10 - October 3, 2022
The median spectral accelerations were rotated to maximum direction using the period
specific ratios from Shahi et al. (2013 & 2014).
6.7.4 The GMPE of Campbell and Borzorgnia requires that the depth to where the shear wave
velocity reaches 2.5 kilometers per second (Z2.5) be defined. Additionally, the GMPEs of
Abrahamson-et al., Boore et al. and Chiou-Youngs require that the depth to where the shear
wave velocity reaches 1 kilometer per second (Z1.0) be defined. The values of Z2.5 and Z1.0 are
internally calculated by the Uniform Hazard Tool.
6.7.5 The MCE uniform hazard response spectrum was adjusted to risk-targeted spectral accelerations
corresponding to a 1 percent chance of collapse in 50 years by using the USGS Risk-Targeted
Ground Motion Calculator and following ASCE 7-16 Section 21.2.1.2 Method 2.
6.7.6 The risk-targeted Maximum Considered Earthquake (MCER) probabilistic response spectrum
is provided on Figure 8.
6.7.7 In accordance with ASCE 7-16, Supplement 1, Section 21.2.2, the largest spectral response
acceleration of the probabilistic response spectrum is less than 1.2Fa, with Fa determined
from Table 11.4.1 and Sa taken as 1.5; therefore, a deterministic analysis of the ground motion
was not required.
6.8 Site-Specific Response Spectrum
6.8.1 The probabilistic MCER response spectra is the Site-Specific MCER. Two thirds of the Site-
Specific MCER is the Design Earthquake (DE) Response Spectrum, provided the results are
not less than 80 percent of the modified General Design Response Spectrum determined by
ASCE 7-16 Section 11.4.6 with Fa and Fv determined as specified in Section 21.3.
6.8.2 Graphical representations of the analyses are presented on Figures 8 and 9. The Site-Specific
Design Earthquake response spectrum at 5 percent damping is presented on Figure 9 and in
tabular form on Figure 10.
6.9 Mapped Acceleration Parameters
6.9.1 Table below summarizes the mapped acceleration parameters obtained from the 2019
California Building Code (CBC; Based on the 2018 International Building Code [IBC] and
ASCE 7-16), Chapter 16A Structural Design, Section 1613A Earthquake Loads. The data
was calculated using the online application Seismic Design Maps, provided by OSHPD. The
short spectral response uses a period of 0.2 second.
Geocon Project No. G1999-42-09B - 11 - October 3, 2022
2019 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2019 CBC Reference
Site Class C Section 1613A.2.2
MCER Ground Motion Spectral Response
Acceleration – Class B (short), SS 0.963g Figure 1613A.2.1(1)
MCER Ground Motion Spectral Response
Acceleration – Class B (1 sec), S1 0.351g Figure 1613A.2.1(2)
Site Coefficient, FA 1.2 Table 1613A.2.3(1)
Site Coefficient, FV 1.5 Table 1613A.2.3(2)
Site Class Modified MCER Spectral Response
Acceleration (short), SMS 1.156g Section 1613A.2.3
(Eqn 16-36)
Site Class Modified MCER Spectral Response
Acceleration – (1 sec), SM1 0.526g Section 1613A.2.3
(Eqn 16-37)
5% Damped Design
Spectral Response Acceleration (short), SDS 0.771g Section 1613A.2.4
(Eqn 16-38)
5% Damped Design
Spectral Response Acceleration (1 sec), SD1 0.351g Section 1613A.2.4
(Eqn 16-39)
TS 0.46 sec ASCE 7-16 Chapter 11
Site Latitude 33.072759 --
Site Longitude -117.232217 --
6.10 Site-Specific Seismic Design Criteria
6.10.1 Based the site-specific ground motion hazard analysis performed, and in accordance with the
ASCE 7-16 Section 21.4, site-specific design acceleration parameters shall be derived using
the results of the site-specific ground motion hazard analysis.
6.10.2 The parameter SDS shall be taken as equal to 90 percent of the maximum spectral
acceleration obtained from the site-specific analysis at any period within the range from 0.2
to 5 seconds, inclusive. The parameter SD1 shall be taken as the maximum value of the
product of the spectral acceleration and period for periods from 1 to 2 seconds, inclusive.
The values of SMS and SM1 shall be taken as 1.5 times the site-specific values of SDS and SD1.
The site-specific design acceleration parameters shall not be less than 80 percent of the
general seismic design values determined by ASCE 7-16 Section 11.4.
6.10.3 Table below presents the site-specific seismic design parameters based on the site-specific
ground motion hazard analysis.
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SITE-SPECIFIC DESIGN ACCELERATION PARAMETERS
Parameter Value
Site Class Modified MCER Spectral Response Acceleration (short), SMS 1.171g
Site Class Modified MCER Spectral Response Acceleration – (1 sec), SM1 0.485g
5% Damped Design Spectral Response Acceleration (short), SDS 0.781g
5% Damped Design Spectral Response Acceleration (1 sec), SD1 0.324g
6.11 Site-Specific Peak Ground Acceleration
6.11.1 The site-specific Maximum Considered Earthquake (MCEG) peak ground acceleration was
evaluated in accordance with ASCE 7-16 Section 21.5. The significant difference between
the MCEG peak ground acceleration and the analysis presented above is that the MCEG is
calculated without the risk-targeted adjustment factors.
6.11.2 The probabilistic peak ground acceleration was analyzed using the same approach as
described above. The analysis used the same Site Class and scenario earthquake. However,
within the probabilistic calculation, the risk-targeted adjustment factor was not applied.
6.11.3 The site-specific MCEG peak ground acceleration, presented in the table below, is taken as
the probabilistic MCEG, provided the value is not less than 80 percent of the value of PGAM
as determined by ASCE 7-16 Equation 11.8.1.
ASCE 7-16 SITE-SPECIFIC PEAK GROUND ACCELERATION
Parameter Value ASCE 7-16 Reference
Site-Specific MCEG Peak Ground Acceleration,
PGAM 0.472g Section 21.5
6.12 Shallow Foundations
6.12.1 The proposed structures can be supported on a shallow foundation system founded in properly
compacted fill. Foundations for the structure should consist of continuous strip footings and/or
isolated spread footings. The following table provides a summary of the foundation design
recommendations.
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SUMMARY OF FOUNDATION RECOMMENDATIONS
Parameter Value
Minimum Continuous Foundation Width, WC 12 inches
Minimum Isolated Foundation Width, WI 24 inches
Minimum Foundation Depth, D 18 Inches Below Lowest Adjacent Grade
Minimum Concrete Reinforcement 4 No. Bars, 2 at the Top and 2 at the Bottom
Allowable Bearing Capacity 2,500 psf
Bearing Capacity Increase 500 psf per Foot of Depth or Width
Maximum Allowable Bearing Capacity 4,000 psf
Estimated Total Settlement 1.0 Inch
Estimated Differential Settlement ½ Inch in 40 Feet
Footing Size Used for Settlement 9-Foot Square
Design Expansion Index 50 or less
6.12.2 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.
Wall/Column Footing Dimension Detail
6.12.3 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.
Geocon Project No. G1999-42-09B - 14 - October 3, 2022
6.12.4 Where buildings or other improvements are planned near the top of a slope steeper than 3:1
(horizontal:vertical), special foundations and/or design considerations are recommended due
to the tendency for lateral soil movement to occur.
Building 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.
Although other improvements, which are relatively rigid or brittle, such as concrete
flatwork or masonry walls, may experience some distress if located near the top of a
slope, it is generally not economical to mitigate this potential. It may be possible,
however, to incorporate design measures that would permit some lateral soil
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
6.12.5 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.
6.12.6 Geocon Incorporated should be consulted to provide additional design parameters as required
by the structural engineer.
6.13 Concrete Slabs On Grade
6.13.1 Concrete slabs on grade for the structures should be constructed in accordance with the following
table.
MINIMUM CONCRETE SLAB-ON-GRADE RECOMMENDATIONS
Parameter Value
Minimum Concrete Slab Thickness 5 inches
Minimum Steel Reinforcement No. 3 Bars 24 Inches on Center, Both Directions
Typical Slab Underlayment 3 to 4 Inches of Sand/Gravel/Base
Design Expansion Index 50 or less
6.13.2 A vapor retarder should underlie slabs that may receive moisture-sensitive floor coverings or
may be used to store moisture-sensitive materials. 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). The
vapor retarder should be installed in a manner that prevents puncture in accordance with
Geocon Project No. G1999-42-09B - 15 - October 3, 2022
manufacturer’s recommendations and ASTM requirements. The project architect or developer
should specify the vapor retarder used based on the type of floor covering that will be installed
and if the structure will possess a humidity-controlled environment.
6.13.3 The project foundation engineer, architect, and/or developer should determine the thickness
of the bedding sand. It is common to have 3 to 4 inches of sand in the southern California
region. We should be contacted to provide recommendations if the bedding sand is thicker
than 6 inches.
6.13.4 The foundation design engineer should provide appropriate concrete mix design criteria and
curing measures to assure proper curing of the slab by reducing potential rapid moisture loss
and subsequent cracking and slab curl. The foundation design engineer should 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.
6.13.5 Concrete slabs should be provided with adequate crack-control joints, construction joints
and/or expansion joints to reduce unsightly shrinkage cracking. American Concrete Institute
(ACI) guidelines should be used to establishing the crack-control-joint spacing. Additional
reinforcement, admixtures, and closer crack-control-joint spacing should be considered where
bare concrete finished floors are planned.
6.13.6 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.
6.13.7 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.
6.13.8 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. Even with the incorporation of the recommendations presented herein,
foundations, stucco walls, and slabs could still crack. The occurrence of concrete-shrinkage
cracks is independent of the supporting soil characteristics. The occurrence cracks can be
reduced and controlled by limiting the slump of the concrete, proper concrete placement and
curing, and by the placement of crack-control joints at appropriate intervals, in particular,
where re-entrant slab corners occur.
Geocon Project No. G1999-42-09B - 16 - October 3, 2022
6.14 Exterior Concrete Flatwork
6.14.1 Exterior concrete flatwork not subject to vehicular traffic should be constructed in accordance
with the recommendations presented in the following table. The recommended steel
reinforcement would help reduce potential cracking.
MINIMUM CONCRETE FLATWORK RECOMMENDATIONS
Expansion
Index, EI Minimum Steel Reinforcement* Options Minimum
Thickness
EI < 50 6x6-W2.9/W2.9 (6x6-6/6) welded wire mesh 4 Inches No. 3 Bars 24 inches on center, Both Directions
*In excess of 8 feet square.
6.14.2 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.
6.14.3 Even with the incorporation of the recommendations of this report, the exterior concrete
flatwork could experience uplift due to expansive soil beneath grade. Flatwork should be
structurally connected to the curbs, where practical, to reduce potential offset between the
curbs and the flatwork.
6.14.4 Concrete flatwork should be provided with crack-control joints to reduce shrinkage cracking.
The project structural engineer determine the appropriate crack-control-joint spacing based
the American Concrete Institute (ACI) guidelines.
6.14.5 Subgrade soil for exterior slabs not subjected to vehicle loads should be compacted in
accordance with recommendations 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.
6.14.6 Base materials will not be required below concrete improvements.
6.14.7 Where exterior flatwork abuts the structure at entrance or exit points, the exterior slab should
be dowelled into the foundation stemwall. This recommendation is intended to reduce
potential differential elevations that could result from differential settlement or minor heave
of the flatwork. The project structural engineer should provide dowelling details.
Geocon Project No. G1999-42-09B - 17 - October 3, 2022
6.14.8 Even with the incorporation of the recommendations presented herein, concrete slabs could
still crack. The occurrence of concrete-shrinkage cracks is independent of the soil supporting
characteristics. Their occurrence can be reduced by limiting the slump of the concrete, the use
of crack-control joints, proper concrete placement, and proper concrete curing. The Portland
Cement Association (PCA) and American Concrete Institute (ACI) provide guidelines for
proper concrete mix, construction, and curing practices, and should be incorporated into
project construction.
6.15 Retaining Walls
6.15.1 Retaining walls should be designed using the values presented in the following table. Soil
with an expansion index (EI) of greater than 50 should not be used as backfill material behind
retaining walls.
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 16H psf
At-Rest/Restrained Walls Additional Uniform Pressure (0 to 8 Feet High) 7H psf
At-Rest/Restrained Walls Additional Uniform Pressure (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
6.15.2 The project retaining walls should be designed as shown in the Retaining Wall Loading
Diagram.
Geocon Project No. G1999-42-09B - 18 - October 3, 2022
Retaining Wall Loading Diagram
6.15.3 Where walls are restrained from movement at the top, an additional uniform pressure should
be applied to the wall (see figure above). 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.
6.15.4 The structural engineer should determine the Seismic Design Category for the project in
accordance with Section 1613.3.5 of the 2019 CBC or Section 11.6 of ASCE 7-10. 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 2019 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.
6.15.5 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.
6.15.6 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
Geocon Project No. G1999-42-09B - 19 - October 3, 2022
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
6.15.7 In general, wall foundations should be designed in accordance with the following table. The
proximity of the foundation to the top of a slope steeper than 3:1 could impact the allowable soil
bearing pressure. 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.
SUMMARY OF RETAINING WALL FOUNDATION RECOMMENDATIONS
Parameter Value
Minimum Retaining Wall Foundation Width 12 inches
Minimum Retaining Wall Foundation Depth 12 Inches
Minimum Steel Reinforcement Per Structural Engineer
Allowable Bearing Capacity 2,500 psf
Estimated Total Settlement 1 Inch
Estimated Differential Settlement ½ Inch in 40 Feet
6.15.8 The recommendations presented herein are generally applicable to the design of rigid concrete
or masonry retaining walls. Should 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.
Geocon Project No. G1999-42-09B - 20 - October 3, 2022
6.15.9 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.
6.15.10 Soil contemplated for use as retaining wall backfill, including imported soil, should be
identified in the field prior to backfill. At that time, Geocon Incorporated should be provided
with samples of the soil for laboratory testing. Modified lateral earth pressures may be
necessary if the backfill soil does not meet the required expansion index or shear strength.
6.15.11 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.
6.16 Lateral Loading
6.16.1 The following table 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.
SUMMARY OF LATERAL LOAD DESIGN RECOMMENDATIONS
Parameter Value
Passive Pressure Fluid Density 300 pcf
Coefficient of Friction (Concrete and Soil) 0.40
Coefficient of Friction (Along Vapor Barrier) 0.2 to 0.25*
*Per manufacturer’s recommendations.
6.16.2 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.
Geocon Project No. G1999-42-09B - 21 - October 3, 2022
6.17 Pavement Recommendations
6.17.1 Pavement areas are not part of the project development. If paved areas are planned, Geocon
Incorporated should be contacted to provide recommendations.
6.18 Site Drainage and Moisture Protection
6.18.1 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 2019 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.
6.18.2 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.
6.18.3 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks. Leaks should be repaired promptly. Detrimental soil movement could
occur if water is allowed to infiltrate the soil for prolonged periods of time.
6.18.4 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.
6.19 Geotechnical Engineer of Record
6.19.1 Geocon Incorporated should be retained as the geotechnical engineer during construction of
site improvements such that the Geotechnical Engineer of Record is maintained. If a new
geotechnical engineer is retained for compaction testing and observation during grading and
construction of improvements, then the replacement geotechnical company will become the
new Geotechnical Engineer of Record and will be responsible for providing geotechnical
consultation and recommendations for the construction phase based on their field observations
and testing during grading and improvements.
Geocon Project No. G1999-42-09B October 3, 2022
LIMITATIONS AND UNIFORMITY OF CONDITIONS
1. The firm that performed the geotechnical investigation for the project 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, that 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 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 upon 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
so that supplemental recommendations can be given. 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 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.
NO SCALE
FIG. 1
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,
SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS
NOT INTENDED FOR CLIENT'S USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENT
SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT
OF SUCH USE OR RELIANCE BY CLIENT.
VICINITY MAP
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
DSK/GTYPD PROJECT NO. G1999 - 42 - 09BRG / RA
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:10/03/2022 1:53PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\DETAILS\G1999-42-09B VicinityMap.dwg
DATE 10 - 03 - 2022
Qudf/
A
A'
B
B
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?
?
?
B-1
B-2
B-3
B-4 Tsa
APPROX. LIMITS
OF PROJECT
PROPOSED
FITNESS CENTER
SITE PLAN/GEOLOGIC MAP
40'
211
Plotted:10/03/2022 1:59PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B GeoMap.dwg
GEOTEC,NICAL CONS9LTANTS
*LAN(E6S (6I:E SAN (IEGO CALI*O6NIA
P,ONE *A< SHEET OF
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
1" =
PROJECT NO.
SCALE
G1999 - 42 - 09B
DATE
FIGURE
10 - 03 - 2022
B-4
?
GEOCON LEGEND
........UNDOCUMENTED FILLQudf
........APPROX. LOCATION OF EXPLORATORY BORING
........APPROX. LOCATION OF GEOLOGIC CROSS-SECTION
B B'
........SANTIAGO FORMATION (Dotted Where Buried)Tsa
........APPROX. LOCATION OF GEOLOGIC CONTACT
(Queried Where Uncertain)
EL
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V
A
T
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(
M
S
L
)
EL
E
V
A
T
I
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N
(
M
S
L
)
DISTANCE (FEET)
SCALE: 1" = 40' (Vert. = Horiz.)
GEOLOGIC CROSS-SECTION A-A'
120
160
200
240
280
320
120
160
200
240
280
320
0 40 80 120 160 200 240 280 300
A A'
EXISTING GRADE
PROPOSED FITNESS CENTER
CROSSING
B-B'
Tsa Tsa
Qudf
??
PROPOSED
BUILDING 1
PROPOSED
BUILDING 2
B-3 B-2
PROPOSED GRADE
ELEVATION = 226.0'
PROPOSED GRADE
ELEVATION = 226.0'
GEOLOGIC CROSS - SECTION A-A'
40'
312
Plotted:10/03/2022 1:57PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B GeologicCross-Sections.dwg
GEOTEC,NICAL CONS9LTANTS
*LAN(ERS (RI:E - SAN (IEGO CALI*ORNIA -
4,ONE - - *A< - SHEET OF
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
1" =
PROJECT NO.
SCALE
G1999 - 42 - 09B
DATE
FIGURE
10 - 03 - 2022
?
GEOCON LEGEND
........UNDOCUMENTED FILLQudf
........APPROX. LOCATION OF GEOLOGIC CONTACT
(Queried Where Uncertain)
........SANTIAGO FORMATIONTsa
........APPROX. LOCATION OF EXPLORATORY BORING
B-3
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" = 40' (Vert. = Horiz.)
GEOLOGIC CROSS-SECTION B-B'
120
160
200
240
280
320
120
160
200
240
280
320
0 40 80 120 160
B B'
EXISTING GRADE
PROPOSED BUILDING 1
B-3B-4
CROSSING
A-A'
??
Tsa Tsa
Qudf
GEOLOGIC CROSS - SECTION B-B'
40'
422
Plotted:10/03/2022 1:57PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B GeologicCross-Sections.dwg
GEOTEC,NICAL CONS9LTANTS
*LAN(ERS (RI:E - SAN (IEGO CALI*ORNIA -
4,ONE - - *A< - SHEET OF
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
1" =
PROJECT NO.
SCALE
G1999 - 42 - 09B
DATE
FIGURE
10 - 03 - 2022
?
GEOCON LEGEND
........APPROX. LOCATION OF GEOLOGIC CONTACT
(Queried Where Uncertain)
........APPROX. LOCATION OF EXPLORATORY BORING
B-4
........UNDOCUMENTED FILLQudf
........SANTIAGO FORMATIONTsa
REGIONAL FAULT MAP
6mi
511
Plotted:10/03/2022 2:01PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B RegionalFaultMap.dwg
GEOTE',NI'AL 'ON7ULTANT7
FLAN(ER7 (RI:E 7AN (IEGO 'ALIFORNIA
P,ONE FA< SHEET OF
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
1" =
PROJECT NO.
SCALE
G1999 - 42 - 09B
DATE
FIGURE
10 - 03 - 2022
REGIONAL GEOLOGIC MAP
2000'
611
SOURCE: Kennedy P. Michael and Tan S. Siang, 2007, Geologic Map of Oceanside 30'x60' Quadrangle, California
U.S. Geological Survey, Department of Earth Sciences, University of California, Riverside
Plotted:10/03/2022 2:06PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B RegionalGeoMap.dwg
GEO8EC,NICAL CON79L8AN87
*LAN(ER7 (RI:E 7AN (IEGO CALI*ORNIA
P,ONE *A< SHEET OF
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
1" =
PROJECT NO.
SCALE
G1999 - 42 - 09B
DATE
FIGURE
10 - 03 - 2022
Plotted:10/03/2022 2:08PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B RegionalGeoMap_Explanation.dwg
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159 SHEET OF
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
1" =
PROJECT NO.
SCALE
G1999 - 42 - 09B
DATE
FIGURE
10 - 03 - 2022
REGIONAL GEOLOGIC 1AP EXPLANATION
NTS
6A11
FIG. 7
REGIONAL SEISMICITY MAP
NO SCALE
EPICENTER OF ≥ 5 CALIFORNIA EARTHQUAKES, 1800-1999
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
DSK/GTYPD PROJECT NO. G1999 - 42 - 09BRG / RA
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:10/03/2022 2:09PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G1999-42-09B Fitness Center-La Costa Canyon HS\SHEETS\G1999-42-09B RegionalSeismicityMap.dwg
DATE 10 - 03 - 2022
Project No.: G1999-42-09B
Checked by: LR
DESIGN RESPONSE SPECTRUM FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
Sep 22 Figure 8
0.00
0.50
1.00
1.50
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
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Period, s
Maximum Rotated Component,
Risk-Targeted MCER
Probabilistic, Risk-Targeted MCER
Probabilistic, Uniform-Hazard MCE
0.00
0.50
1.00
1.50
2.00
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Sp
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Period, s
Maximum Rotated Component, Risk-
Targeted MCER
1.2*Fa
Project No.: G1999-42-09B
DESIGN RESPONSE SPECTRUM FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
Checked by: LR Sep 22 Figure 9
0.00
0.50
1.00
1.50
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Sp
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Period, s
Site-Specific, Maximum Considered
Earthquake Response Spectrum
Site-Specific, Design Response Spectrum
80% modified General ResponseSpectrum
SMS = g
SM1 = g
SDS = g
SD1 = g
Project No.: G1999-42-09B
"--" Indicates that spectral period was not used at that calculation step
0.118
0.105
0.084
0.079
0.070
0.056
0.079
0.070
0.056
--
0.104
0.080
--
--
--
--
1.260
1.2600.064
--
0.905
0.905
1.171
0.485
0.781
0.324
3.64
4.00
5.00
--
0.091
0.071
--
0.082
MRC, Risk-
Targeted
Probablistic
0.514
84th
Percentile,
Deterministic
--
--
0.485
0.225
Site-Specific
Maximum
Considered
Earthquake
0.514
1.022
1.072
1.301
1.175
0.949
0.885
0.645
Site-Specific
Design
Earthquake
0.343
80% Modifed
General
Response
Spectrum
0.247
--
--
--
--
DESIGN RESPONSE SPECTRUM FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
Checked by: LR Sep 22 Figure 10
0.909
0.905
--
1.190
1.220
1.230
--
1.230
0.907
0.912
0.911
--
0.915
0.915
0.907
1.240
1.240
1.240
3.00
1.00
2.00
0.50
0.75
0.30
0.46
0.10
0.20
0.09
Spectral
Period
(seconds)
0.00
Probabilistic
Uniform-
Hazard
0.472
Risk-
Targeted,
Probabilistic
0.569
0.431
0.200
0.432
Risk Factor,
Cr
0.915
--
Maximum-
Rotated
Componet
Scale Factor
1.190
0.126
--
0.901
1.067
0.955
--
0.993
1.170
1.049
--
0.786
--
0.719
0.521
0.391
0.182
0.114
0.150
1.250
--
1.072
1.301
1.175
--
0.885
0.645
0.485
0.225
0.143
0.324
0.590
0.095 0.1430.094
0.616
0.616
0.616
0.616
0.616
0.562
0.374
0.281
0.140--
--
0.682
0.715
0.868
0.783
0.633
--
--
0.430
--
Reference: ASCE 7-16 21.4 DESIGN ACCELERATION PARAMETERS
Where the site-specific procedure is used to determine the design ground motion in accordance with Section 21.3, the parameter SDSshall be taken as 90% of the maximum spectral acceleration, Sa, obtained from the site-specific spectrum, at any period within the range
from 0.2 to 5 s, inclusive. The parameter SD1 shall be taken as the maximum value of the product, TSa, for periods from 1 to 2 s for sites
with vs,30 > 1,200 ft/s (vs,30 > 365.76 m/s) and for periods from 1 to 5 s for sites with vs,30 ≤ 1,200 ft/=s (vs,30 ≤ 365.76 m/s). The
parameters SMS and SM1 shall be taken as 1.5 times SDS and SD1, respectively. The values so obtained shall not be less than 80% of the
values determined in accordance with Section 11.4.3 for SMS and SM1 and Section 11.4.5 for SDS and SD1.
APPENDIX A
Geocon Project No. G1999-42-09B - 23 - October 3 2022
APPENDIX A
FIELD INVESTIGATION
The field investigation was performed on August 11, 2022 and consisted of drilling four, small-
diameter exploratory borings at the approximate locations shown on Figure 2. The small-diameter
borings were drilled to depths of up to 19.5 feet below existing grade using a limited-access drill rig
equipped with 5-inch-diameter, solid-stem augers. Relatively undisturbed samples were obtained with
the drill rig by driving a 3-inch O. D., split-tube sampler 12 inches into the undisturbed soil mass with
blows from a 140-pound hammer falling 30 inches. The split-tube sampler was equipped with 1-inch-
high by 23/8-inch-diameter, brass sampler rings to facilitate sample removal and testing. Disturbed bulk
samples were obtained from drill cuttings.
The soil conditions encountered in the borings were visually examined, classified, and logged in general
conformance with the American Society for Testing and Materials (ASTM) Practice for Description
and Identification of Soils (Visual-Manual Procedure D2488). The logs of the exploratory borings are
presented on Figures A-1 through A-4. The logs depict the various soil types encountered and indicate
the depths at which samples were obtained.
SANTIAGO FORMATION (Tsa)
Dense, moist, light olive, Silty, fine to coarse SAND
-Becomes very dense
Very dense, moist, light olive with orange mottling, Silty, fine to coarse
SAND
-Becomes saturated (local seepage)
Dense, moist to very wet, light olive and red brown mottled, Clayey SAND
Very stiff, moist to very moist, dark olive, Sandy, fine CLAY
BORING TERMINATED AT 19.5 FEET
Seepage encountered at 12 feet
Backfilled with cuttings
108.0
117.6
114.7
116.2
12.0
9.3
14.8
16.0
B1-1
B1-2
B1-3
B1-4
B1-5
B1-6
10/27"
50/6"
50/4"
10/11"
50/6"
SM
SM
SC
CL
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
8
10
12
14
16
18
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)
LIMITED ACCESS RIG W/4.5" AUGER 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
K. OVERTURF CO
N
T
E
N
T
(
%
)
SAMPLE
NO.08-11-2022
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)225'
G1999-42-09B.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.
G1999-42-09B
SANTIAGO FORMATION (Tsa)
Medium dense, moist, light olive/tan, Silty, fine to coarse SAND
Dense, moist, light olive to red orange, Silty, fine to coarse SAND
-Becomes light olive to yellow
BORING TERMINATED AT 11 FEET
No groundwater encountered
Backfilled with cuttings and cement mixture
112.1
110.9
112.3
110.0
8.7
9.7
13.7
12.5
B2-1
B2-2
B2-3
B2-4
B2-5
23
35
35
33
SM
SM
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
8
10
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)
LIMITED ACCESS RIG W/4.5" AUGER 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
K. OVERTURF CO
N
T
E
N
T
(
%
)
SAMPLE
NO.08-11-2022
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)225'
G1999-42-09B.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.
G1999-42-09B
UNDOCUMENTED FILL (Qudf)
Stiff, moist to very moist, dark olive and black, Sandy CLAY; high plasticity
SANTIAGO FORMATION (Tsa)
Dense, very moist, olive, Silty, fine to coarse SAND
Stiff, moist to very moist, dark olive, Sandy CLAY
-Becomes hard
-Becomes stiff, very moist, olive to medium brown
BORING TERMINATED AT 19.5 FEET
No groundwater encountered
Backfilled with cuttings and cement mixture
107.1
104.0
101.1
110.4
112.0
115.5
20.6
21.2
20.5
18.8
18.3
15.6
B3-1
B3-2
B3-3
B3-4
B3-5
B3-6
B3-7
25
20
27
28
55
38
CH
SM
CL
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
8
10
12
14
16
18
Figure A-3,
Log of Boring B 3, Page 1 of 1
DR
Y
D
E
N
S
I
T
Y
(P
.
C
.
F
.
)
... DRIVE SAMPLE (UNDISTURBED)
LIMITED ACCESS RIG W/4.5" AUGER 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 3
... CHUNK SAMPLE
DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOIL
CLASS
(USCS)
GR
O
U
N
D
W
A
T
E
R
K. OVERTURF CO
N
T
E
N
T
(
%
)
SAMPLE
NO.08-11-2022
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)225'
G1999-42-09B.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.
G1999-42-09B
SANTIAGO FORMATION (Tsa)
Stiff to hard, moist, dark yellow to light olive, Sandy CLAY; some silt,
medium to high plasticity
Hard, moist, dark olive, Sandy CLAY
BORING TERMINATED AT 10 FEET
No groundwater encountered
Backfilled with cuttings and sand
110.3
112.5
18.5
18.6
B4-1
B4-2
B4-3
50
60
CH
CL
... DISTURBED OR BAG SAMPLE
GEOCON
DEPTH
IN
FEET
0
2
4
6
8
10
Figure A-4,
Log of Boring B 4, Page 1 of 1
DR
Y
D
E
N
S
I
T
Y
(P
.
C
.
F
.
)
... DRIVE SAMPLE (UNDISTURBED)
LIMITED ACCESS RIG W/4.5" AUGER 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 4
... CHUNK SAMPLE
DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOIL
CLASS
(USCS)
GR
O
U
N
D
W
A
T
E
R
K. OVERTURF CO
N
T
E
N
T
(
%
)
SAMPLE
NO.08-11-2022
SAMPLE SYMBOLS
MO
I
S
T
U
R
E
BY:EQUIPMENT
ELEV. (MSL.)225'
G1999-42-09B.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.
G1999-42-09B
APPENDIX B
Geocon Project No. G1999-42-09B - B-1 October 3, 2022
APPENDIX B
LABORATORY TESTING
Laboratory tests were performed in accordance with generally accepted test methods of the American
Society for Testing and Materials (ASTM) or other suggested procedures. Selected soil samples were tested
for their in-place dry density, moisture content, and direct shear characteristics. Selected soil samples were
remolded to determine their compaction and expansion potential characteristics. Additionally, samples
were tested for water-soluble sulfate content, chloride ion content, pH, and minimum resistivity
characteristics.
The results of our laboratory tests are presented on Tables B-I through B-VI. The in-place dry density and
moisture content results are indicated on the exploratory boring logs.
TABLE B-I
SUMMARY OF DIRECT SHEAR TEST RESULTS
ASTM D 3080
Sample No. Dry Density
(pcf)
Moisture Content (%) Angle of Internal
Friction (degrees)
Cohesion
(psf) Before Test After Test
B2-3 110.9 9.7 16.8 32 600
B4-2 110.3 18.5 21.2 32 850
TABLE B-II
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
D 4829
Sample
No.
Moisture Content (%) Dry
Density
(pcf)
Expansion
Index
Expansion
Potential Soil Unit Before Test After Test
B1-1 9.4 17.6 111.7 33 Low Santiago Formation
B3-1 11.4 23.6 105.4 102 High Undocumented Fill
B4-1 10.8 23.2 107.5 97 High Santiago Formation
Geocon Project No. G1999-42-09B - B-2 October 3, 2022
TABLE B-III
SUMMARY OF LABORATORY OF PH AND MINIMUM RESISTIVITY TEST RESULTS
CALIFORNIA TEST NO. 643
Sample No. pH Minimum Resistivity (ohm-centimeters)
B2-1 8.8 1400
B3-1 8.0 370
B4-1 8.0 450
TABLE B-IV
SUMMARY OF LABORATORY SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sample No. Water-Soluble Sulfate (%) Sulfate Severity
B2-1 0.0004 Not Applicable
B3-1 0.361 Severe
B4-1 0.060 Not Applicable
TABLE B-V
SUMMARY OF LABORATORY CHLORIDE ION CONTENT TEST RESULTS
AASHTO T 291
Sample No. Chloride Ion Content (ppm) Chloride Ion Content (%)
B2-1 70 0.007
B3-1 350 0.035
B4-1 340 0.034
TABLE B-VI
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY
AND OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557
Sample No. Description Maximum Dry
Density (pcf)
Optimum Moisture
Content (% dry wt.)
B3-1 Dark olive and black sandy CLAY 122.6 12.4
APPENDIX C
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
FOR
FITNESS CENTER
LA COSTA CANYON HIGH SCHOOL
CARLSBAD, CALIFORNIA
PROJECT NO. G1999-42-09B
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.
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.
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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.
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TYPICAL CANYON DRAIN DETAIL
7.2 Slope drains within stability fill keyways should use 4-inch-diameter (or lager) pipes.
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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.
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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.
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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.
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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.
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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. G1999-42-09B October 3, 2022
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