HomeMy WebLinkAboutPD 2021-0026; 3805 ALDER AVE; RESPONSE TO CITY OF CARLSBAD LAND DEVELOPMENT ENGINEERING; 2024-06-07Universal Engineering Sciences (UES)
1441 Montiel Road, Suite 115
Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
Environmental Consulting | Geotechnical Engineering | Materials Testing & Inspections
Occupational Health & Safety | Building Sciences & Code Compliance | Virtual Design Consulting
June 7, 2024 UES Job No. 10-15939G
Tony Jaramillo
3805 Alder Avenue
Carlsbad, California 92008
Telephone: 267-847-4045 Via Email: tony.jaramillo@gmail.com
Subject: Response to City of Carlsbad Land Development Engineering
Proposed Single-Family Residence, 3805 Alder Avenue (1st Review)
Project ID: PD2021-0026, Grading Permit No. GR2021-0026
References: End of Document
Mr. Jaramillo: Construction Testing & Engineering Inc. (CTE) has been acquired by Universal Engineering Sciences (UES). As a result,
our future project submittals will be under the new UES letterhead. Project personnel will remain the same and UES
will take full responsibility for all previous work submitted under the CTE letterhead and agreements. According to
the referenced letter issued on April 22, 2024, UES has assumed the responsibility as geotechnical engineer of record
for the subject project.
As requested, Universal Engineering Sciences (UES) has prepared the following response to the City of Carlsbad
Third-Party Geotechnical Review comments dated May 1, 2024. The responses provided below are numbered based
on the comment numbers. A copy of the City comments is provided as Attachment 1.
Comment No. 1: The submitted “Preliminary Geotechnical Investigation…” report by CTE appears to consist of a
geotechnical investigation for a previously contemplated building addition to the existing residence at the subject
site and not specifically for the currently proposed new single-family residence. Consequently, please provide
updates for all aspects of the geotechnical report (site grading, foundation and floor slab, etc.) as necessary to
completely address the proposed construction of a single-family residence and associated improvements.
Response to Comment No. 1: A supplemental subsurface exploration was performed in the vicinity of the existing
residence as documented in the CTE report dated May 9, 2024 (attached). In addition, on May 21, 2024 two bulk
samples of surficial soil were obtained at locations S-1 and S-2 shown in Figures 2 and 2A, Geologic/Exploration
Location Map. Based on our review and the results of the supplemental exploratory work, the recommendations
provided in the geotechnical investigation report by CTE dated April 20, 2022 remain applicable to the site grading,
foundation design, floor slab, etc. for the new residence to be constructed at the site.
Comment No. 2: The submitted “Preliminary Geotechnical Investigation…” by CTE is approximately 2 years old and
references an antiquated revision of the California Building Code. Please review the most current revisions of the
grading and foundation plans for the proposed residence and improvements and provide updated geotechnical
conclusions/recommendations as necessary to address the current scope of the project. Please also update the
report as necessary to address the currently adopted 2022 California Building Code and ASCE 7- 16.
Response to City of Carlsbad Comments Page 2
3805 Alder Avenue, Carlsbad, California
June 7, 2024 UES Job No. 10-15939G
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
Response to Comment No. 2: UES has reviewed the grading plans prepared by Fitzmaurice Consulting dated March
24, 2024 and the foundation plans by Aramark Concepts dated January 15, 2024. Based on our review, the site is
suitable for the proposed development as designed provided the design and construction of the project incorporates
the recommendations included in the referenced geotechnical report by CTE (2022) and additional
recommendations presented herein.
Updated seismic ground motion values were derived using the ASCE Hazard Tool application in accordance with the
ASCE 7-16 Standard that is incorporated into the 2022 California Building Code (CBC). The 2022 CBC seismic ground
motion values presented in Table 1 for Seismic Site Class C and site coordinates of Latitude 33.1599°N and Longitude
117.3196°W are identical to the 2019 CBC values presented in the CTE (2022) report which are also based on ASCE 7-
16 Standard. These values are intended for the design of structures to resist the effects of earthquake ground
motions. All references in previous CTE reports to 2019 CBC should be updated to 2022 CBC.
TABLE 1
SEISMIC GROUND MOTION VALUES (2022 CBC & ASCE 7-16)
PARAMETER VALUE 2022 CBC/ASCE 7-16 REFERENCE
Seismic Site Class C ASCE 16, Chapter 20
Mapped Spectral Response Acceleration Parameter, SS 1.010 Figure 1613.2.1 (1)
Mapped Spectral Response Acceleration Parameter, S1 0.368 Figure 1613.2.1 (2)
Seismic Coefficient, Fa 1.200 Table 1613.2.3 (1)
Seismic Coefficient, Fv 1.500 Table 1613.2.3 (2)
MCE Spectral Response Acceleration Parameter, SMS 1.213 Section 1613.2.3
MCE Spectral Response Acceleration Parameter, SM1 0.552 Section 1613.2.3
Design Spectral Response Acceleration, Parameter SDS 0.808 Section 1613.2.5(1)
Design Spectral Response Acceleration, Parameter SD1 0.368 Section 1613.2.5 (2)
Peak Ground Acceleration PGAM 0.531 ASCE 16, Section 11.8.3
Seismic Design Category D Section 1603.1.5 (6)
Comment No. 3: Please provide a statement addressing the potential impact of the proposed project on adjacent
properties.
Response to Comment No. 3: Based on our review of the grading plans by Fitzmaurice Consulting (2024), adjacent
properties should not be impacted provided temporary slopes are inclined away from property lines at a minimum
1:1 (horizontal: vertical) and evaluated by a UES geotechnical representative during grading to determine if
excavation in slot cuts or additional setback is necessary.
Comment No. 4: Please provide a description of the proposed project and discuss the proposed grading (depths and
limits of cut and fill, etc., necessary to establish proposed grades) and the construction of any proposed hardscape
improvements, site walls, etc., for the current project.
Response to Comment No. 4: The proposed project consists of demolition of the existing residence and construction
of a new two-story residence with a 3-car garage at the same general location. Associated improvements include a 4
ft. high retaining wall to the south and west of the new residence, stormwater and utility installations, landscape and
Response to City of Carlsbad Comments Page 3
3805 Alder Avenue, Carlsbad, California
June 7, 2024 UES Job No. 10-15939G
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
concrete flatwork areas. The project site appears to be underlain by approximately six feet of undocumented fill. As
such, it is recommended that existing undocumented fill (and residual soils, if encountered) within a lateral distance
of at least five feet from the new residence and retaining wall footprint be overexcavated to competent formational
materials and compacted fill be placed for the building pad. Following preparation of the building pad as
recommended herein, previously provided recommendations by CTE (2022) for foundation design and construction
of hardscape improvements, site walls, etc. are considered suitable for the design of the new residence.
Comment No. 5: Please provide an updated “Geologic/Exploration Map” utilizing the most current revision of the
grading plan for the project as the base map and at a sufficiently large scale to clearly demonstrate the proposed
project and show all of the geotechnical information shown on the “Geologic/Exploration Map” of the submitted
report – a) existing site topography, b) proposed residential structure and improvements, c) proposed finished
grades, d) geologic units and geologic structure, e) the locations of subsurface exploration (borings and test pits) for
the currently proposed residence and previous slope restoration work, and f) the proposed slope restoration as
applicable.
Response to Comment No. 5: The updated “Geologic/Exploration Map” is presented in the attached Figure 2 for the
proposed slope restoration and Figure 2A for the proposed residential structure and associated improvements.
Comment No. 6: Please provide an updated Geologic Cross Section A-A’ to also show (along with all of the
information shown on the “Cross Section A-A’” of the submitted report) - a) proposed finish grades for the residence
and improvements and adjacent slope as applicable, b) the limits of the proposed residence and associated
improvements, c) the geologic structure of the Santiago formation, d) the limits and depths of proposed remedial
grading for the proposed residence and improvements, e) temporary slopes necessary for the remedial grading and
for any retaining wall construction, f) slope setback for the residence and improvements, and g) the locations of
subsurface exploration (borings and test pits) for the currently proposed residence and previous slope restoration
work. Please provide the cross section at a scale sufficiently large to clearly show the information requested above.
Response to Comment No. 6: The updated Geologic Cross Section A-A’ is presented in the attached Figure 3.
Comment No. 7: Please provide a summary discussion (based on the consultant’s previous work for the grading
permit for the proposed slope restoration) addressing the geologic structure (direction/dip of bedding, fracturing,
etc.) of the Old Paralic deposits and Santiago formation bedrock and the relationship between the structural geology
of the units underlying the site and gross stability of the area of proposed residential construction and adjacent
approximate 85’ high east descending hillside. Please discuss both surficial and gross slope stability of existing
hillside relative to the proposed residential development.
Response to Comment No. 7: According to our review of regional geologic maps and experience in the vicinity of
the site, the Very Old Paralic Deposits are massive with no defined bedding. Bedding in the Santiago Formation
generally descends to the southwest at approximately eight degrees (which would be dipping into slope and be
favorable at the site). Bedding attitudes measured throughout the site ranged from neutral to out of slope in isolated
areas. However, based on geologic contacts observed in the soil borings and those mapped on May 31, 2024 by our
geologist during slope grading, the bedding appeared to be generally flat and global structure generally appears to
be neutral.
The global and surficial slope stability analyses, presented in Figure 4 through 6 were performed assuming that
grading for the residential pad was completed and the proposed slope buttresses were in place. The slope stability
analyses incorporated conservative strength parameters (friction angle and cohesion) for the various units as
Response to City of Carlsbad Comments Page 4
3805 Alder Avenue, Carlsbad, California
June 7, 2024 UES Job No. 10-15939G
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
follows: Compacted Fill (φ=25°, c=200 psf), Very Old Paralic Deposits (φ=35°, c=900 psf), Santiago Formation-
Sandstone (φ=35°, c=700 psf), and Santiago Formation-Clay (φ=15°, c=500 psf ). In particular, the Santiago Formation-
Clay [Tsa (clay)] unit strength parameters were reduced significantly to represent a remolded shear value. The
attached global and surficial slope stability analyses indicate that the slope will be stable with a factor of safety
greater than 1.5 for the static condition and greater than 1.1 for the seismic (pseudo-static) condition. In addition,
isolated areas with out-of-slope bedding are anticipated to be mitigated with the proposed compacted fill
buttresses.
Comment No. 8: Please provide a discussion addressing seismically induced landsliding with respect to the proposed
residential development.
Response to Comment No. 8: The previously observed surficial failures and unstable portions of the existing slope
are anticipated to be mitigated and protected against future failures after the proposed grading and buttress fills are
completed. Based on the results of the attached slope stability analyses, the potential for seismically induced
landsliding after site grading is completed will be very low.
Comment No. 9: Please provide the Seismic Design category in accordance with Section 1603 of the 2022 California
Building Code.
Response to Comment No. 9: As indicated in Table 1 (see response to Comment No. 2), the applicable Seismic
Design Category for this project is D.
Comment No. 10: Strength (direct shear) testing of the on-site soils that will apparently be used as fill as part of the
remedial grading (existing undocumented fill and residual soil) and support proposed foundations/slabs is not
provided in the report (direct shear tests presented in the report appear to be from the geotechnical report
addressing the hillside/slope restoration work and consist of in-situ tests of the Old Paralic deposits and Santiago
formation materials). Please provide the appropriate laboratory testing to substantiate the values for bearing
capacity, passive pressure, coefficient of friction, and active pressure that are presented in the report for the
proposed single-family residence. If presumptive values are being recommended by the consultant, please state the
reference and use values consistent with the appropriate soil type (soil class) in Tables 1806.2 and 1610.1 of the
2022 California Building Code. Please justify the soil type by laboratory testing if something other than soil class 5 in
Tables 1806.2 and 1610.1 of the CBC is provided as the basis for the assumed values.
Response to Comment No. 10: A remolded direct shear test was performed on the undocumented fill sample
recovered at location S-1. The sample was remolded to 90% of the maximum unit weight per ASTM D 1557 (Modified
Proctor). The attached test results indicate friction angle of 35 degrees and cohesion of 370 psf. Based on these
results, the values provided for bearing capacity, coefficient of friction, passive and active pressures in the CTE (2022)
report are conservative and may be used for design.
Comment No. 11: Expansion Index testing presented in the report indicates an EI of 55 (Medium). As soils with
Expansion Index (EI) over 20 are considered expansive and require mitigation in accordance with Sections 1803.5.3
and 1808.6 of the 2022 CBC, please provide recommendations to satisfy the 2022 California Building Code. Please
indicate the method of Section 1808.6 that is being recommended to satisfy the requirement for expansive soils, and
provide the Effective Plasticity Index and any other parameters for slab-on- ground design in accordance with
1808.6.2 and WRI/CRSI Design of Slab-on-Ground floors or a post-tensioned design in accordance with PTI DC 10.5
and provide a statement that the foundation/slab system for the proposed residential structures will meet the
Response to City of Carlsbad Comments Page 5
3805 Alder Avenue, Carlsbad, California
June 7, 2024 UES Job No. 10-15939G
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
requirements of Section 1808.6 of the 2022 California Building Code
Response to Comment No. 11: Expansion index testing was performed on bulk samples S-1 and S-2 collected from
the building pad area. The attached test results indicate expansion index values of 1 and 12, respectively, which
correspond to “very low” (EI≤20) expansion potential. The geotechnical report by CTE (2022) anticipated “low”
(21≤EI≤50) expansion potential conditions. Additional expansion index testing will be performed during pad grading.
Comment No. 12: Soluble sulfate testing is not provided in the reviewed geotechnical report. Consequently, please
provide recommendations for sulfate resistant concrete (compressive strength, w/c ratio, type cement) consistent
with the 2022 California Building Code and ACI 318-19, Tables 19.3.1.1 and 19.3.2.1 assuming a “Severe” (S2)
exposure class; or provide site specific testing to support a different recommendation.
Response to Comment No. 12: Corrosivity testing was performed on samples S-1 and S-2 collected from the building
pad area to evaluate the potential corrosive effects of site soil on concrete foundations and buried metallic utilities.
Based on the attached test results, near-surface soils at the site generally correspond to class S0 sulfate exposure
and present negligible corrosion potential for Portland cement concrete. It is also interpreted that site soils have
mild corrosive potential to buried metallic improvements. Therefore, it would likely be prudent for buried utilities to
utilize plastic piping and/or conduits, where feasible. However, UES does not practice corrosion engineering and
recommends that a corrosion engineer or other qualified consultant be contacted if site specific corrosivity issues
are of concern.
Comment No. 13: Please clarify the remedial grading recommendations (depths of removals, distance of removals
beyond the footprint of the proposed residence and improvements, etc.) for the proposed residential structure and
associated hardscape improvements and site walls.
Response to Comment No. 13: As indicated in the response to Comment No. 4, it is recommended that existing
undocumented fill (and residual soils, if encountered) within a lateral distance of at least five feet from the new
residence and retaining wall be overexcavated to competent formational materials and compacted fill be placed for
the building pad. For pavement or flatwork areas, the recommendations provided in the CTE (2022) report are still
valid and state that overexcavation should be conducted to a depth of two feet below proposed subgrade, or to the
depth of suitable native material, whichever is shallower.
Comment No. 14: With respect to remedial grading for the proposed residence and hardscape improvements, if all
of the existing undocumented fill/residual soils (up to 5-1/2’ deep) are not removed by the grading (see “Preliminary
Geotechnical Investigation – Addendum Letter 01” and pages 11 and 12 of the geotechnical report), please
thoroughly explain the ramifications of not making complete removals of the surficial soils down to competent Old
Paralic deposits and describe the potential distress that could occur to the proposed residence and improvements as
a result of the incomplete removal of the surficial soils.
Response to Comment No. 14: As indicated in the response to Comment No. 4, it is recommended that all
undocumented fill (and residual soils, if encountered) within a lateral distance of at least five feet from the new
residence and retaining wall footprint be overexcavated to competent formational materials.
Comment No. 15: Please provide the basis for the 12’ slope setback recommended in the geotechnical report versus
the guidelines presented in Section 1808.7.2 of the 2022 California Building Code (setback of H/3) for the
approximate 85’ high slope that bounds the eastern side of the project area.
Response to Comment No. 15: According to our review of the grading plans by Fitzmaurice Consulting (2024), the
Response to City of Carlsbad Comments Page 6
3805 Alder Avenue, Carlsbad, California
June 7, 2024 UES Job No. 10-15939G
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
foundations for the new residence will be located at a minimum distance of 33 feet from the proposed top of slope
location which satisfies the H/3 setback requirement. The 12’ slope setback recommendation was based on the
assumption that foundations for the new residence will be embedded at least two feet in competent formational
materials as recommended in the CTE (2022) report and are not likely to be affected by potential fill slope relaxation.
Comment No. 16: Please clarify the minimum depth of embedment into the Old Paralic deposits and/or Santiago
formation for any footings that may be deepened through the existing undocumented fill/residual soil.
Response to Comment No. 16: As indicated in Section 5.7.1 New Foundations of the CTE (2022) report, all
foundations for the new residence and retaining wall should be embedded at least two feet into competent
formational materials.
Comment No. 17: Please provide recommendations for concrete slab thickness for proposed hardscape
improvements (walkways, driveway, patios, etc.) from a geotechnical standpoint.
Response to Comment No. 17: Based on the anticipated “very low” to “low” expansion potential of subgrade soils,
exterior concrete flatwork should have a minimum thickness of 5 inches. Additional recommendations provided in
Section 5.10 Exterior Flatwork of the CTE (2022) report remain applicable.
Comment No. 18: Please provide recommendations for retaining wall subdrains (type of pipe, amount/size of gravel,
filter fabric etc.) from a geotechnical standpoint.
Response to Comment No. 18: A general detail for Retaining Wall Drainage, which may be appropriate for the
subject site based on the review of the project structural engineer and architect, is attached as Figure 7.
Waterproofing should be as specified by the project architect or the waterproofing specialty consultant.
Comment No. 19: Please evaluate and discuss the potential for storm water infiltration at the subject site as part of
the proposed project.
Response to Comment No. 19: As indicated in Sections 5.11 Drainage and 5.12 Slopes of the CTE (2022) report,
generally it is not recommended to allow water to infiltrate the building pad or adjacent to slopes. The installation of
unlined stormwater basins or storm-water treatment devices may increase the possibility of adverse effects
associated with high groundwater on the building, retaining wall foundation and adjacent descending slope. Surface
runoff should be collected and directed away from improvements by means of appropriate erosion-reducing devices
and positive drainage should be established around the proposed improvements. Although properly constructed
slopes on this site should be grossly stable, the soils may be susceptible to erosion. Therefore, runoff water should
not be permitted to drain over the edges of slopes unless that water is confined to properly designed and
constructed drainage facilities. Erosion-resistant vegetation should be maintained on the face of all slopes. Typically,
soils along the top portion of a fill slope face will creep laterally. UES does not recommend building distress-sensitive
improvements within 10 feet of slope crests.
Comment No. 20: Please provide a complete summary list of the geotechnical observation/testing services that
should be performed as part of the construction of the proposed single-family residence and associated
improvements.
Response to City of Carlsbad Comments Page 7
3805 Alder Avenue, Carlsbad, California
June 7, 2024 UES Job No. 10-15939G
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | TeamUES.com
Response to Comment No. 20: In general, UES will provide the following services during grading and construction of
the proposed single-family residence and associated improvements as it relates to geotechnical engineering:
• The UES geotechnical engineer/geologist will review the geotechnical report, project plans and specifications with
the field technician and grading contractor to ensure proper execution of the project requirements;
• The field technician will perform continuous observation and testing of fill placement as required by the California
Building Code and provide a daily field report that outlines the work done and any discrepancies or non-
conformance with respect to project requirements so that they can be tracked and resolved efficiently;
• The field technician will collect samples of soil being used or proposed for use as fill so that appropriate laboratory
testing can be performed (maximum dry density/optimum moisture content relationships, expansion index, soil
classification, sand equivalent, remolded direct shear, etc.);
• The engineer will review laboratory testing results and provide necessary information to field technician directly.
•The field technician and engineer/geologist will periodically meet at the site to evaluate geologic exposures and
ensure testing and observation requirements are being met; and,
• The engineer/geologist and support staff will prepare a final geotechnical report that summarizes the work done
during construction, including all test results and a statement regarding compliance with the project geotechnical
requirements, plans, specifications and all applicable city and county codes.
Conditions of the referenced reports remain applicable unless specifically superseded herein. We appreciate the
opportunity to be of service on this project. Should you have any questions or need further information please do
not hesitate to contact this office.
Respectfully,
Universal Engineering Sciences (UES)
Andres Bernal, GE #2715 Martin E. Siem, CEG 2311
Geotechnical Engineer Engineering Geologist
AB/MS:ach
S:\Projects\10-15000 to 10-15999 Projects\10-15939G (Alder Ave)\Response to Comments 5.2024
ATTACHMENTS:
-Figure 2 - Geologic/Exploration Location Map - Proposed Slope Restoration
-Figure 2A - Geologic/Exploration Location Map - Proposed Residence
- Figure 3 - Cross Section A-A’
- Figure 4 - Slope Stability Analysis A-A’ (Static)
- Figure 5 - Slope Stability Analysis A-A’ (Pseudo-static)
- Figure 6 - Surficial Slope Stability Analysis
- Figure 7 - Retaining Wall Drainage
-Appendix A - References
-Appendix B - Laboratory Test Results
-Appendix C - Preliminary Geotechnical Investigation – Addendum 02, Proposed Alder Avenue, 3805 Alder
Avenue, Carlsbad, California, CTE Job No.: 10-15939G, dated May 9, 2024.
-City of Carlsbad, Land Development Engineering, 1st Review Comments, dated May 1, 2024.
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CROSS SECTION A-A'
PROPOSED ADU AND POOL ADDITION
3805 ALDER AVENUE
CARLSBAD CALIFORNIA
.
1.909
Name: Qudf-QyaSlope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 200 psf
Effective Friction Angle: 25 °
Phi-B: 0 °
Piezometric Line: 1
Name: Tsa (clay)Slope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 500 psf
Effective Friction Angle: 15 °Phi-B: 0 °
Piezometric Line: 1
Name: Qcf
Slope Stability Material Model: Mohr-Coulomb
Unit Weight: 125 pcfEffective Cohesion: 200 psfEffective Friction Angle: 25 °Phi-B: 0 °Piezometric Line: 1
Name: Tsa (sand)Slope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcf
Effective Cohesion: 700 psf
Effective Friction Angle: 35 °
Phi-B: 0 °
Piezometric Line: 1
Name: Qcf
Slope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 200 psfEffective Friction Angle: 25 °
Phi-B: 0 °Piezometric Line: 1
Name: Qvop
Slope Stability Material Model: Mohr-Coulomb
Unit Weight: 125 pcf
Effective Cohesion: 900 psfEffective Friction Angle: 35 °Phi-B: 0 °Piezometric Line: 1
File Name: A-A' response 5-24.gsz
Method: Spencer
Direction of movement: Left to Right
Slip Surface Option: Entry and Exit
Factor of Safety: 1.909
FIGURE 4
□
□
1.299
Name: Qudf-QyaSlope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 200 psf
Effective Friction Angle: 25 °
Phi-B: 0 °
Piezometric Line: 1
Name: Tsa (clay)
Slope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 500 psfEffective Friction Angle: 15 °
Phi-B: 0 °Piezometric Line: 1
Name: Qcf
Slope Stability Material Model: Mohr-Coulomb
Unit Weight: 125 pcf
Effective Cohesion: 200 psfEffective Friction Angle: 25 °Phi-B: 0 °Piezometric Line: 1
Name: Tsa (sand)
Slope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 700 psfEffective Friction Angle: 35 °Phi-B: 0 °Piezometric Line: 1
Name: Qudf
Slope Stability Material Model: Mohr-Coulomb
Unit Weight: 125 pcf
Effective Cohesion: 200 psf
Effective Friction Angle: 25 °Phi-B: 0 °Piezometric Line: 1
Name: QvopSlope Stability Material Model: Mohr-CoulombUnit Weight: 125 pcfEffective Cohesion: 900 psfEffective Friction Angle: 35 °Phi-B: 0 °Piezometric Line: 1
File Name: A-A' response 5-24 seismic.gsz
Method: Spencer
Direction of movement: Left to Right
Slip Surface Option: Entry and Exit
Factor of Safety: 1.299
FIGURE 5
□
□
□
□
□
-------------------------------------------------------------------------------------------111!:::~----------+ □
Surficial Slope Stability:
UES Job Number:10-15939G Date: 17-May-24
Assumptions:
1) Saturation of Slope Surface
2) Sufficient Permeability to Establish Water Flow
Yellow Boxes Require Input
Variables:
Ws = Saturated Soil Unit Weight =125
Ww = Unit Weight of Water (62.4 lbs/ft^3)=62.4
z = Layer Thickness, (feet)=3
a = Angle of Slope Face, (degrees)=26.6
phi = Internal Friction Angle, (degrees)=25
c = Apparent Cohesion, (psf)=200
Equations:
Pw = Water Pressure Head = (z)cos^2(a))
u = Pore Water Pressure = (Ww)(z)(cos^2(a))
Fd = (0.5)(z)(Ws)(sin(2a))150.1
Fr = (z)(Ws-Ww)(cos^2(a))(tan(phi))+c 270.0
Factor of Safety (FS) = Fr/Fd 1.80
Calculation I
FIGURE 6
-
-
SLOPE SURFACE
---------a
FAILURE PA H
FLOW LINES
1
1
SELECT GRANULAR WALL
BACKFILL COMPACTED
TO 90% RELATIVE COMPACTION
3/4" GRAVEL SURROUNDED
BY FILTER FABRIC (MIRAFI
140 N. OR EQUIVALENT)
-OR-
PREFABRICATED
DRAINAGE BOARD
FINISH GRADE
SPECIFIED BY ARCHITECT
RETAINING WALL
WATERPROOFING TO BE
12" TO 18" OF LOWER PERMEABILITY MATERIAL COMPACTED TO 90% RELATIVE COMPACTION
1' MIN
4" DIA. PERFORATED PVCPIPE (SCHEDULE 40 OREQUIVALENT). MINIMUM1% GRADIENT TO SUITABLEOUTLET
WALL FOOTING
*CONCEPTUAL DRAWING 7
• • • l • ...
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RITAINING WALL DIWNAGI Dn'AIL SCALE: DATE:
NO SCALE 4/2024
UES JOB NO.: FIGURE:
4830.2400027
APPENDIX A
REFERENCES
Preliminary Geotechnical Investigation – Addendum 02
Proposed Alder Avenue
3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated May 9, 2024.
Update Geotechnical Recommendations
Proposed Alder Avenue
3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated April 22, 2024.
Preliminary Geotechnical Investigation--Addendum 01
Proposed 3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated February 12, 2024.
Preliminary Geotechnical Investigation
Proposed Residential Addition, 3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated February 26, 2021, revised April 20, 2022.
Response to: The City of Carlsbad Third-Party Geotechnical Review (First)
Project Number: 9427.1 (dated August 24, 2021)
Jaramillo Residence, 3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated February 4, 2022.
Response to: The City of Carlsbad Comments
Jaramillo Residence, 3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated September 29, 2021.
Geotechnical Investigation and Slope Evaluation
Jaramillo Residence, 3805 Alder Avenue, Carlsbad, California
CTE Job No.: 10-15939G, dated February 26, 2021 (Revised April 12, 2021).
Grading Plans for:
3805 Alder Avenue, Slope Restoration
Project No. PD2021-0026, Drawing 532-6A
Prepared by Fitzmaurice Consulting, Revision 2 dated March 24, 2024.
Structural Plans
Jaramillo Residence, 3805 Alder Ave., Carlsbad, CA 92008
Prepared by Aramark Concepts, dated January 15, 2024.
Alder Avenue
Project No. 4830.2115939
Page 2
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | oneues.com
Laboratory tests were performed on selected soil samples to evaluate their engineering properties. Tests
were performed following test methods of the American Society for Testing and Materials, or other
accepted standards. The following presents a brief description of the various test methods used.
Laboratory results are presented in the following section of this Appendix.
Classification (ASTM D2487)
Earth materials encountered were visually and texturally classified in accordance with the Unified Soil
Classification System (USCS/ASTM D2487) and ASTM D2488. Material classifications are indicated on the
logs of the exploratory borings presented in Appendix B.
Expansion Index Test (ASTM D4829)
Expansion index testing was performed on selected samples of the earth materials encountered in general
accordance with the ASTM D4829 test method. The test determines the expansion potential of the
materials encountered. The test results are presented in the following section of this appendix.
Laboratory Compaction Characteristics Test (ASTM D1557)
Laboratory compaction characteristics testing was performed on selected samples of the earth materials
encountered in general accordance with the ASTM D1557 test method. The test establishes the laboratory
maximum dry density and optimum moisture content of the tested materials and are also used to aid in
Direct Shear Test (ASTM D3080)
Direct Shear testing was performed in general accordance with the ASTM D3080 test method to aid in
evaluating the soil strength characteristics of the on‐site earth materials encountered. Testing is
performed on undisturbed specimens obtained from drive‐samples and/or on specimens remolded in the
laboratory to a specific moisture content and density. The test consists of placing the specimen in a direct
shearing device, applying a specified normal stress, and then shearing the sample at a constant rate under
drained conditions. This is repeated under a series of specified normal stresses. The shearing resistance
and horizontal displacements are measured and recorded as the soil specimen is sheared. The shearing is
continued well beyond the point of maximum resistance (peak strength) to determine a constant or
residual value (ultimate strength). The test results are presented in the following section of this appendix.
Soil Corrosivity Tests
The water‐soluble sulfate and chloride content, the resistivity, and pH of selected samples were
performed by a third‐party laboratory in general accordance with California Test Methods. The tests
results are useful in the assessment of the degree of corrosivity of the earth materials encountered with
regard to concrete and normal grade steel.
APPENDIX B
LABORATORY TEST METHODS AND RESULTS
'' LIES,.
Alder Avenue
Project No. 4830.2115939
Page 3
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | oneues.com
EXPANSION INDEX
(ASTM D4829)
Sample Location Expansion Index Expansion Potential
S‐1 1 VERY LOW
S‐2 12 VERY LOW
LABORATORY COMPACTION CHARACTERISTICS
(ASTM D1557)
Sample Location Maximum Dry Density
(pounds per cubic foot)
Optimum Moisture
(percent)
S‐1 121.1 8.6
CHEMICAL ANALYSIS FOR SULFATE
(CALIFORNIA TEST 422)
Sample Location Depth
(feet)
Results
ppm
S‐1 N/A 18.5
S‐2 N/A 28.9
CHEMICAL ANALYSIS FOR CHLORIDE
(CALIFORNIA TEST 422)
Sample Location Depth
(feet)
Results
ppm
S‐1 N/A ND
S‐2 N/A 1.8
CHEMICAL ANALYSIS FOR p.H.
Sample Location Depth
(feet)
Results
S‐1 N/A 6.80
S‐2 N/A 8.04
'' LIES,.
Alder Avenue
Project No. 4830.2115939
Page 4
1441 Montiel Road, Suite 115, Escondido, CA 92026
p. 760.746.4955 | oneues.com
CHEMICAL ANALYSIS FOR RESISTIVITY
(CALIFORNIA TEST 643)
Sample Location Depth
(feet)
Results
ohms‐cm
S‐1 N/A 27200
S‐2 N/A 9450
'' LIES,.
SHEAR STRENGTH TEST - ASTM D3080
Job Name:
Project Number: 5/21/2024
Lab Number:5/30/2024
Sample Location:L.N.
Sample Description:Angle Of Friction: 35.4
Cohesion:
Alder Avenue
370 psf
Initial Dry Density (pcf): 121.1
Initial Moisture (%): 8.6
Final Moisture (%): 16.0
S-1
Brown (SM) Remolded to 90 %
4830.2115939.0000
35849
Sample Date:
Test Date:
Tested By:
0
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6
8
10
12
14
16
18
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May 9, 2024 CTE Job No. 10-15939G
Mr. Tony Jaramillo
3805 Alder Avenue
Carlsbad, California 92024
Telephone: (267) 847-4045 Via Email: tony.jaramillo@gmail.com
Subject: Preliminary Geotechnical Investigation – Addendum 02
Proposed Alder Avenue
3805 Alder Avenue, Carlsbad, California
References: At end of document
Mr. Jaramillo:
As requested, Construction Testing & Engineering, Inc. (CTE) has performed additional review and field
investigation for the proposed new pool and ADU at the subject site. On April 29, 2024, a CTE geologist
advanced three additional hand auger borings (HB-7, HB-8, and HB-9) in the vicinity of the proposed pool and
ADU footprints. Figure 1 provides a Site Index Map and Figure 2 provides an updated Geologic/Exploration
Location Map. Boring logs are provided as Attachment A.
ADU AREA
The ADU area appears to be underlain by approximately six feet of undocumented fill. As such, it is
recommended in the area for the ADU footprint (and to a lateral distance of at least five feet) existing
undocumented fill (and residual soils, if encountered) be overexcavated to competent formational materials
and to a minimum depth of two feet below the depth of proposed footings (whichever is deeper) and
compacted fill be placed for the building pad. Following preparation of the building pad as recommended
herein, previously provided recommendations for foundation design (CTE, 2022) are considered suitable for the
design of the ADU.
POOL AREA
Based on interpolation between borings HB-1 & HB-2 and HB-7, HB-8, & HB-9, the pool area is anticipated to be
underlain by approximately zero to six feet of undocumented fill. As such, it is recommended that the pool
bottom be deepened to bear entirely onto formational materials, or that all undocumented fill (and residual
soils, if encountered) be overexcavated to competent formational materials and to a minimum depth of two
feet below the bottom of pool (whichever is deeper), and compacted fill be placed for the support of the pool.
The overexcavation should extend a minimum lateral distance of three feet beyond the pool footprint.
Following preparation of the pool area as recommended herein, previously provided recommendations for
foundation design (CTE, 2022) are considered suitable for the design of the pool.
Other recommendations provided in CTE’s referenced geotechnical report and addendum remain applicable,
and are superseded by recommendations herein where conflicts exist. Additionally, CTE reserves the right to
observe overexavation bottoms and recommend deeper removals, as necessary, based on exposed conditions.
APPENDIX C
A Universal
Engineering Construction Testing & Engineering, Inc.
Sciences
Company Inspection I Testing I Geotechnical I Environmental & Construction Engineering I Civil Engineering I Surveying
1441 Montiel Road, Suite 115 I Escondido, CA 92026 I Ph (760) 746-4955 I Fax (760) 746-9806 I www.cte-inc.net
Preliminary Geotechnical Investigation – Addendum 02 Page 2
Proposed Alder Avenue
3805 Alder Avenue, Carlsbad, California
May 9, 2024 CTE Job No. 10-15939G
S:\Projects\10-15000 to 10-15999 Projects\10-15939G (Alder Ave)\ADU + Pool Addition - Addendum 02\Ltr_Pool&ADU Addendum 02.doc
Limitations provided in CTE’s referenced report are considered to apply to recommendations provided in this
addendum letter.
This document is subject to the same limitations as the referenced geotechnical report. The opportunity to be
of service is appreciated. If you have any questions, please contact our office.
Respectfully submitted,
CONSTRUCTION TESTING & ENGINEERING, INC.
Colm J. Kenny, GE #3201
Senior Engineer
CJK:ach
Attachments:
Figure 1—Site Index Map
Figure 2—Geologic/Exploration Location Map
Boring Logs
References:
Preliminary Geotechnical Investigation – Addendum 01
Proposed Alder Avenue
3805 Alder Avenue, Carlsbad, California
CTE Job No. 10-15939G, Dated February 12, 2024
Preliminary Geotechnical Investigation
Proposed Residential Addition
3805 Alder Avenue, Carlsbad, California
CTE Job No. 10-15939G, Dated April 20, 2022
C.
SITE
APN: 2070632500
SITE INDEX MAP
PROPOSED ADU AND POOL ADDITION
3805 ALDER AVENUE CARLSBAD, CALIFORNIA
SCALE: DATE:
AS SHOWN 4/2024
CTE JOB NO.: FIGURE:
4830.2115939 1
B-1
B-2
A
A'
1229
12
52
38
12
HB-4
HB-5
HB-3
HB-6
Qvop Qudf
Qvop
Qudf
Qvop
Qudf
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Qsw Tsa
Tsa
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Qsw
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HB-1
HB-2
Qvop
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TP-1
HB-7
HB-8
B-2 APPROXIMATE BORING LOCATION (2/21)
LEGEND
QUATERNARY UNDOCUMENTED FILL
TERTIARY SANTIAGO FORMATION
Qudf
Tsa
APPROXIMATE GEOLOGIC CONTACT
QUATERNARY SLOPEWASHQsw
QUATERNARY VERY OLD PARALIC DEPOSITSQvop
QUATERNARY LANDSLIDE DEPOSITSQls
CROSS SECTION A-A'A A'
APPROXIMATE JOINT ATTITUDE52
12 APPROXIMATE BEDDING ATTITUDE
HB-9 APPROXIMATE HAND-AUGER BORING LOCATION
TP-1 APPROXIMATE TEST PIT
APPROXIMATE ADU AND POOL ADDITION
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DEFINITION OF TERMS
PRIMARY DIVISIONS SYMBOLS SECONDARY DIVISIONS
WELL GRADED GRAVELS, GRAVEL‐SAND MIXTURES
LITTLE OR NO FINES
POORLY GRADED GRAVELS OR GRAVEL SAND MIXTURES,
LITTLE OF NO FINES
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NON‐PLASTIC FINES
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CLAYEY SANDS, SAND‐CLAY MIXTURES, PLASTIC FINES
INORGANIC SILTS, VERY FINE SANDS, ROCK FLOUR, SILTY
OR CLAYEY FINE SANDS, SLIGHTLY PLASTIC CLAYEY SILTS
INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,
GRAVELLY, SANDY, SILTS OR LEAN CLAYS
ORGANIC SILTS AND ORGANIC CLAYS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE
SANDY OR SILTY SOILS, ELASTIC SILTS
INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS
ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,
ORGANIC SILTY CLAYS
PEAT AND OTHER HIGHLY ORGANIC SOILS
GRAIN SIZES
GRAVEL SAND
COARSE FINE COARSE MEDIUM FINE
12" 3" 3/4" 4 10 40 200
CLEAR SQUARE SIEVE OPENING U.S. STANDARD SIEVE SIZE
ADDITIONAL TESTS
(OTHER THAN TEST PIT AND BORING LOG COLUMN HEADINGS)
MAX‐ Maximum Dry Density PM‐ Permeability PP‐ Pocket Penetrometer
GS‐ Grain Size Distribution SG‐ Specific Gravity WA‐ Wash Analysis
SE‐ Sand Equivalent HA‐ Hydrometer Analysis DS‐ Direct Shear
EI‐ Expansion Index AL‐ Atterberg Limits UC‐ Unconfined Compression
CHM‐ Sulfate and Chloride RV‐ R‐Value MD‐ Moisture/Density
Content , pH, Resistivity CN‐ Consolidation M‐ Moisture
COR ‐ Corrosivity CP‐ Collapse Potential SC‐ Swell Compression
SD‐ Sample Disturbed HC‐ Hydrocollapse OI‐ Organic Impurities
REM‐ Remolded
FIGURE: BL1
GW
SILTS AND CLAYSLIQUID LIMIT ISLESS THAN 50
SILTS AND CLAYSLIQUID LIMIT ISGREATER THAN 50
SANDSMORE THANHALF OFCOARSEFRACTION ISSMALLER THANNO. 4 SIEVE
GRAVELSMORE THANHALF OFCOARSEFRACTION ISLARGER THANNO. 4 SIEVE
CLEANGRAVELS< 5% FINES
GRAVELS WITH FINES
CLEANSANDS< 5% FINES
SANDSWITH FINES
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Total Depth: 4.6'No Groundwater Encountered Backfilled on 2/10/2022
FIGURE:
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:2/10/2022
DD Bulk ~292 Feet
BORING LOG: HB-1
DESCRIPTION
HB-1
0
5
10
15
QUATERNARY UNDOCUMENTED FILL:Loose to medium dense, moist, brown, silty fine to medium grained SAND, trace fine roots.
QUATERNARY VERY OLD PARALIC DEPOSITS:Medium dense, moist, reddish brown, silty fine to medium grained SAND, oxidized, massive.
Medium dense, moist, moddled reddish brown and olive gray, clayey fine to medium grained SAND.
Medium dense, slightly moist, reddish brown, silty fine to medium grained SAND, oxidized, massive.
~, LIES™
Universal Engineering Sciences (UES)
1441 M ontiel Road, Suite 115
Escondid o, CA 9 2026
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Total Depth: 5.2'No Groundwater Encountered Backfilled on 2/10/2022
FIGURE:
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:2/10/2022
DD Bulk ~294 Feet
BORING LOG: HB-2
DESCRIPTION
HB-2
0
5
10
15
RESIDUAL SOIL:Loose to medium dense, moist, brown, silty fine to medium grained SAND.
QUATERNARY VERY OLD PARALIC DEPOSITS:Medium dense, moist, reddish brown, silty fine to medium grained SAND, oxidized, massive.
Medium dense, moist, moddled reddish brown and olive gray, clayey fine to medium grained SAND.
Medium dense, slightly moist, reddish brown, silty fine to medium grained SAND, moderately cemented.
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Universil E111gineering Sciences (UES)
1441 Montiel Road, Suite 115
Escoridido,. CA 92026
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Total Depth: 4.4'No Groundwater Encountered Backfilled on 2/10/2022
FIGURE:
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:2/10/2022
DD Bulk ~295 Feet
BORING LOG: HB-3
DESCRIPTION
HB-3
0
5
10
15
RESIDUAL SOIL:Loose to medium dense, moist, brown, silty fine to medium grained SAND.
QUATERNARY VERY OLD PARALIC DEPOSITS:Medium dense, moist, reddish brown, silty fine to medium grained SAND, oxidized, massive.
Medium dense, moist, reddish brown, clayey fine to medium grained SAND.
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1441 Montiel Road, Suite 115
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SM
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Total Depth: 1'No Groundwater Encountered Backfilled on 2/10/2022
FIGURE:
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:2/10/2022
DD Bulk ~299 Feet
BORING LOG: HB-4
DESCRIPTION
HB-4
0
5
10
15
QUATERNARY UNDOCUMENTED FILL:Loose, dry, brown, silty fine to medium grained SAND, trace fine gravel.
QUATERNARY VERY OLD PARALIC DEPOSITS:Medium dense, slightly moist, reddish brown, silty fine to medium grained SAND, oxidized, massive.
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Total Depth: 3.6'No Groundwater Encountered Backfilled on 2/10/2022
FIGURE:
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:2/10/2022
DD Bulk ~298 Feet
BORING LOG: HB-5
DESCRIPTION
HB-5
0
5
10
15
RESIDUAL SOIL:Loose to medium dense, slightly moist, brown, silty fine to medium grained SAND.
QUATERNARY VERY OLD PARALIC DEPOSITS:Medium dense, moist, reddish brown, clayey fine to medium grained SAND.
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Total Depth: 6'No Groundwater Encountered Backfilled on 2/10/2022
FIGURE:
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10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:2/10/2022
DD Bulk ~296 Feet
BORING LOG: HB-6
DESCRIPTION
HB-6
0
5
10
15
QUATERNARY UNDOCUMENTED FILL:Loose to medium dense, slightly moist, brown, silty fine to medium grained SAND.
QUATERNARY VERY OLD PARALIC DEPOSITS:
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Universil E111gineering Sciences (UES)
1441 Montiel Road, Suit e 115
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SC-CL Medium dense, moist, red-brown, clayey fine to medium grained SAND with trace light gray CLAY.
"SC"
Total Depth: 7' (Refusal)No Groundwater Encountered Backfilled on 4/29/2024
FIGURE:HB-7
DJT Bulk ~285 Feet
BORING LOG: HB-7
DESCRIPTION
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:4/29/2024
0
5
10
15
QUATERNARY UNDOCUMENTED FILL:Loose to medium dense, dry to slightly moist, dark red-brown, silty fine to medium grained SAND, with roots.
QUATERNARY VERY OLD PARALIC DEPOSITS:Very dense, dry, light red-brown, clayey fine to medium grained SAND, or sandstone.
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Universil E111gineering Sciences (UES)
1441 Montiel Road, Suit e 115
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Becomes loose at 2 feet.
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SC-CL Loose to medium dense, moist, red-brown, clayey fine to medium grained SAND, trace light gray clay.
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Total Depth: 6' (Refusal)No Groundwater Encountered Backfilled on 4/29/2024
FIGURE:HB-8
DJT Bulk ~285 Feet
BORING LOG: HB-8
DESCRIPTION
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:4/29/2024
0
5
10
15
QUATERNARY UNDOCUMENTED FILL:Medium dense, slightly moist, dark red-brown, silty fine to medium grained SAND with roots and trace gravel.
QUATERNARY VERY OLD PARALIC DEPOSITS:Very dense, slightly moist, light red-brown, clayey fine to medium grained SAND, or sandstone.
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Universil E111gineering Sciences (UES)
1441 Montiel Road, Suit e 115
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Total Depth: 4' (Refusal)No Groundwater Encountered Backfilled on 4/29/2024
FIGURE:HB-9
DJT Bulk ~284 Feet
BORING LOG: HB-9
DESCRIPTION
Alder Avenue UES
10-15939G Hand-Auger with 3" Bucket EXCAVATION DATE:4/29/2024
0
5
10
15
RESIDUAL SOIL:Medium dense, slightly moist to moist, red-brown, silty to clayey fine to medium grained SAND.
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~, LIES™
Universil E111gineering Sciences (UES)
1441 Montiel Road, Suit e 115
Escoridido,. CA 92026
p,. 760.746.4955 I Te,aml.JES.com
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ATTACHMENT
City of Carlsbad, Land Development Engineering, Dated May 1, 2024 (1st Review)
GEOTECHNICAL REPORT REVIEW
__________________________________________________________
DATE: May 1, 2024
TO: City of Carlsbad
Land Development Engineering
1635 Faraday Avenue
Carlsbad, CA 92008
Attention: David Rick
PROJECT ID: PD2021-0026
GRADING PERMIT NO.: GR2021-0026
SUBJECT: Proposed Single-Family Residence, 3805 Alder Avenue, (1st review)
Items Submitted by Applicant Items Being Returned to Applicant
“Preliminary Geotechnical Investigation,
Proposed Residential Addition, 3805 Alder
Avenue, Carlsbad, California,” by Construction
Testing & Engineering, Inc. (CTE), dated April 20,
2022.
Written report review comments.
“Preliminary Geotechnical Investigation –
Addendum 01, Proposed Alder Avenue, 3805
Alder Avenue, Carlsbad, California,” by
Construction Testing & Engineering, Inc. (CTE),
dated February 12, 2024.
Written report review comments.
Based on our review of the submitted geotechnical reports, we are providing the following
comments that should be addressed prior to the next submittal. Please provide complete and
thorough written responses to all comments. Please note that the following comments are specific
to the proposed construction of a single-family residence at the subject site and do not address
the geotechnical conditions associated with the proposed earthwork and slope restoration of the
descending hillside east of the proposed residence that was previously proposed and reviewed
under grading permit GR2021-0026. With the above in mind, the following comments have been
provided based on the review of the submitted reports for the proposed residence.
GEOTECHNICAL COMMENTS:
1. The submitted “Preliminary Geotechnical Investigation…” report by CTE appears to
consist of a geotechnical investigation for a previously contemplated building addition to
the existing residence at the subject site and not specifically for the currently proposed
new single-family residence. Consequently, please provide updates for all aspects of the
geotechnical report (site grading, foundation and floor slab, etc.) as necessary to
GR2021-0026
May 1, 2024
Page 2 of 4
completely address the proposed construction of a single-family residence and associated
improvements.
2. The submitted “Preliminary Geotechnical Investigation…” by CTE is approximately 2 years
old and references an antiquated revision of the California Building Code. Please review
the most current revisions of the grading and foundation plans for the proposed residence
and improvements and provide updated geotechnical conclusions/recommendations as
necessary to address the current scope of the project. Please also update the report as
necessary to address the currently adopted 2022 California Building Code and ASCE 7-
16.
3. Please provide a statement addressing the potential impact of the proposed project on
adjacent properties.
4. Please provide a description of the proposed project and discuss the proposed grading
(depths and limits of cut and fill, etc., necessary to establish proposed grades) and the
construction of any proposed hardscape improvements, site walls, etc., for the current
project.
5. Please provide an updated “Geologic/Exploration Map” utilizing the most current revision
of the grading plan for the project as the base map and at a sufficiently large scale to
clearly demonstrate the proposed project and show all of the geotechnical information
shown on the “Geologic/Exploration Map” of the submitted report – a) existing site
topography, b) proposed residential structure and improvements, c) proposed finished
grades, d) geologic units and geologic structure, e) the locations of subsurface exploration
(borings and test pits) for the currently proposed residence and previous slope restoration
work, and f) the proposed slope restoration as applicable.
6. Please provide an updated Geologic Cross Section A-A’ to also show (along with all of the
information shown on the “Cross Section A-A’” of the submitted report) - a) proposed finish
grades for the residence and improvements and adjacent slope as applicable, b) the limits
of the proposed residence and associated improvements, c) the geologic structure of the
Santiago formation, d) the limits and depths of proposed remedial grading for the proposed
residence and improvements, e) temporary slopes necessary for the remedial grading and
for any retaining wall construction, f) slope setback for the residence and improvements,
and g) the locations of subsurface exploration (borings and test pits) for the currently
proposed residence and previous slope restoration work. Please provide the cross section
at a scale sufficiently large to clearly show the information requested above.
7. Please provide a summary discussion (based on the consultant’s previous work for the
grading permit for the proposed slope restoration) addressing the geologic structure
(direction/dip of bedding, fracturing, etc.) of the Old Paralic deposits and Santiago
formation bedrock and the relationship between the structural geology of the units
underlying the site and gross stability of the area of proposed residential construction and
adjacent approximate 85’ high east descending hillside. Please discuss both surficial and
gross slope stability of existing hillside relative to the proposed residential development.
8. Please provide a discussion addressing seismically induced landsliding with respect to the
proposed residential development.
9. Please provide the Seismic Design category in accordance with Section 1603 of the 2022
California Building Code.
GR2021-0026
May 1, 2024
Page 3 of 4
10. Strength (direct shear) testing of the on-site soils that will apparently be used as fill as part
of the remedial grading (existing undocumented fill and residual soil) and support
proposed foundations/slabs is not provided in the report (direct shear tests presented in
the report appear to be from the geotechnical report addressing the hillside/slope
restoration work and consist of in-situ tests of the Old Paralic deposits and Santiago
formation materials). Please provide the appropriate laboratory testing to substantiate the
values for bearing capacity, passive pressure, coefficient of friction, and active pressure
that are presented in the report for the proposed single-family residence. If presumptive
values are being recommended by the consultant, please state the reference and use
values consistent with the appropriate soil type (soil class) in Tables 1806.2 and 1610.1
of the 2022 California Building Code. Please justify the soil type by laboratory testing if
something other than soil class 5 in Tables 1806.2 and 1610.1 of the CBC is provided as
the basis for the assumed values.
11. Expansion Index testing presented in the report indicates an EI of 55 (Medium). As soils
with Expansion Index (EI) over 20 are considered expansive and require mitigation in
accordance with Sections 1803.5.3 and 1808.6 of the 2022 CBC, please provide
recommendations to satisfy the 2022 California Building Code. Please indicate the method
of Section 1808.6 that is being recommended to satisfy the requirement for expansive
soils, and provide the Effective Plasticity Index and any other parameters for slab-on-
ground design in accordance with 1808.6.2 and WRI/CRSI Design of Slab-on-Ground
floors or a post-tensioned design in accordance with PTI DC 10.5 and provide a statement
that the foundation/slab system for the proposed residential structures will meet the
requirements of Section 1808.6 of the 2022 California Building Code.
12. Soluble sulfate testing is not provided in the reviewed geotechnical report. Consequently,
please provide recommendations for sulfate resistant concrete (compressive strength, w/c
ratio, type cement) consistent with the 2022 California Building Code and ACI 318-19,
Tables 19.3.1.1 and 19.3.2.1 assuming a “Severe” (S2) exposure class; or provide site
specific testing to support a different recommendation.
13. Please clarify the remedial grading recommendations (depths of removals, distance of
removals beyond the footprint of the proposed residence and improvements, etc.) for the
proposed residential structure and associated hardscape improvements and site walls.
14. With respect to remedial grading for the proposed residence and hardscape
improvements, if all of the existing undocumented fill/residual soils (up to 5-1/2’ deep) are
not removed by the grading (see “Preliminary Geotechnical Investigation – Addendum
Letter 01” and pages 11 and 12 of the geotechnical report), please thoroughly explain the
ramifications of not making complete removals of the surficial soils down to competent Old
Paralic deposits and describe the potential distress that could occur to the proposed
residence and improvements as a result of the incomplete removal of the surficial soils.
15. Please provide the basis for the 12’ slope setback recommended in the geotechnical
report versus the guidelines presented in Section 1808.7.2 of the 2022 California Building
Code (setback of H/3) for the approximate 85’ high slope that bounds the eastern side of
the project area.
16. Please clarify the minimum depth of embedment into the Old Paralic deposits and/or
Santiago formation for any footings that may be deepened through the existing
undocumented fill/residual soil.
GR2021-0026
May 1, 2024
Page 4 of 4
17. Please provide recommendations for concrete slab thickness for proposed hardscape
improvements (walkways, driveway, patios, etc.) from a geotechnical standpoint.
18. Please provide recommendations for retaining wall subdrains (type of pipe, amount/size
of gravel, filter fabric etc.) from a geotechnical standpoint.
19. Please evaluate and discuss the potential for storm water infiltration at the subject site as
part of the proposed project.
20. Please provide a complete summery list of the geotechnical observation/testing services
that should be performed as part of the construction of the proposed single-family
residence and associated improvements.