HomeMy WebLinkAboutCT 2017-0003; LA COSTA TOWN SQUARE PARCEL 3 RESIDENTIAL; RESPONSE TO CITY OF CARLSBAD GEOTECHNICAL RETAINING WALL REVIEW COMMENT; 2024-05-13Geotechnical C Geologic C Coastal C Environmental
5741 Palmer Way Suite D, Carlsbad, CA 92010
TEL: (760) 438-3155 - FAX: (760) 931-0915
www.geosoilsinc.com
May 13, 2024
W.O. 8144-B-SC
Woodside 05S, LP
1250 Corona Pointe Court, Suite 500
Corona, California 92879
Attention: Mr. Craig Moraes
Subject: Response to City of Carlsbad Geotechnical Retaining Wall Review Comment,
La Costa Town Square Project, Carlsbad, San Diego County, California,
APN 223-050-73-00, Grading Permit No.: GR2022-0001
Dear Mr. Moraes:
In accordance with the City of Carlsbad geotechnical retaining wall review comment
received, GeoSoils, Inc. (GSI) is herein presenting our specific response addressing the
review comment for the La Costa Town Square Project, Carlsbad, San Diego County,
California. The scope of our services has included a review of the geotechnical retaining
wall review comment prepared by True North Compliance Services (TNCS, 2024) reviewer
on behalf of the City of Carlsbad, review of previous geotechnical reports for the project
site by GSI (see Appendix A), review of the updated rough grading plans by SB&O, Inc.
(SB&O, 2024), evaluations of the data obtained, and preparation of this response report.
The following discussions present only the pertinent geotechnical City review comment
received in italics, followed by GSI’s response:
Review Comment No. S4:
“Per sheet 1, soils engineer certificate. The geotechnical report for this project is date
6/17/2021. Reports dated more than two years from the submittal date should be
accompanied by a geotechnical update letter noting that the report is still valid, updating
and code references and providing any additional recommendations that should be
followed.”
Response to Geotechnical Review Comment No. S4:
Comment Acknowledged. During progression of the project and in accordance with the
adopted California Building Code (CBC, 2022), a geotechnical update and addendum
memorandum to our initial geotechnical due diligence report (GSI, 2021) was previously
provided for the La Costa Town Square Project in February of 2023. This geotechnical
addendum (GSI, 2023e) provided updated seismic design parameters in accordance with
,.
GSi
Geo Soi ls, Inc.
the 2022 CBC, and indicated the conclusions and recommendations in our referenced
reports remain pertinent and applicable, and should be appropriately implemented during
planning, design, and construction. For convenience, a copy of our geotechnical update
and addendum for the subject site (GSI, 2023e) is provided in Appendix B.
LIMITATIONS
The materials encountered on the project site and used for our analysis are believed to be
representative of the area; however, soil and bedrock materials vary in character between
excavations and natural outcrops, or conditions exposed during mass grading. Site
conditions may vary due to seasonal changes or other factors.
Inasmuch as this study is based upon our review and engineering analyses, the
conclusions and recommendations are professional opinions. These opinions have been
derived in accordance with current standards of practice, and no warranty, either express
or implied, is given. Standards of practice are subject to change with time. GSI assumes
no responsibility or liability for work or testing performed by others, or their inaction; or
work performed when GSI is not requested to be onsite to evaluate if our
recommendations have been properly implemented. Use of this report constitutes an
agreement and consent by the user to all the limitations outlined above, notwithstanding
any other agreements that may be in place. In addition, this report may be subject to
review by the controlling authorities. Thus, this report brings to completion our scope of
services for this portion of the project.
Woodside 05S, LP W.O. 8144-B-SC
La Costa Town Square Project May 13, 2024
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The opportunity to be of service is sincerely appreciated.
questions, please do not ·,__ tact our office.
Respectfully submitte
GeoSoils, Inc.
If you should have any
~ ryl{ t:. _J:: ~
Todd A. Greer ~c~
Engineering Geologist, CEG 2377
TAG/SJC/ef
Enclosure: Appendix A -References
Appendix B -Copy of GSI 2023e
Distribution: (1) Addressee (PDF via email)
Woodside 05S, LP
Geotechnical Engineer, GE 2057
La Costa Town Square Project
File:e:\wp21\8100\8144b.rtc GeoSoils,lnc.
W.O. 8144-B-SC
May 13, 2024
Page 3
APPENDIX A
REFERENCES
GeoSoils, Inc.
APPENDIX A
REFERENCES
California Building Standards Commission, 2022, California Building Code, California Code
of Regulations, Title 24, Part 2, Volumes 1 and 2, based on the 2021 International
Building Code, effective January 1, 2023.
GeoSoils, Inc., 2023a, Responses to third-party review comments regarding building
setbacks from the existing mechanically stabilized earth wall, La Costa Town
Square Project, Carlsbad, San Diego County, California, APN 223-050-73-00,
Project ID: CT2017-0003, Grading Permit No.: GR2022-0001, W.O. 8144-B-SC,
dated October 25.
_____, 2023b, Geotechnical update and response to City of Carlsbad Engineering
Department plan check comment regarding building setbacks from the existing
mechanically stabilized earth retaining wall, La Costa Town Square project,
Carlsbad, San Diego County, California, APN 223-050-73-00,
project ID: CT2017-0003, grading permit no.: GR2022-0001, W.O. 8144-B-SC, dated
September 21.
_____, 2023c, Summary of geotechnical observation and testing services during repair of
existing Anchor Retaining Wall No. 1, La Costa Town Square Project, Carlsbad,
San Diego County, California, APN 223-050-73-00, Project ID: CT2017-0003,
Grading Permit No.: GR2022-0001, W.O. 8144-F-SC, dated August 3.
_____, 2023d, Memorandum: Review of construction change No. 2 rough grading plans,
La Costa Town Square project, City of Carlsbad, San Diego County, California,
APN 223-050-73-00, project no.: CT 2017-0003, drawing no.: 536-1A,
W.O. 8144-B-SC, dated August 1.
_____, 2023e, Geotechnical update and addendum to “Geotechnical Due Diligence Report
and Attachments, La Costa Town Square Project, City of Carlsbad, California
APN 223-050-73-00,” W.O. 8144-A-SC, dated February 9, 2023, W.O. 8144-A-SC,
dated June 20.
_____, 2023f, Memorandum: Review of precise grading plans, La Costa Town Square
project, City of Carlsbad, California APN 223-050-73-00, project no.: CT 2017-0003,
drawing no.: 536-1A, W.O. 8144-B-SC, dated May 30.
_____, 2023g, Memorandum: Geotechnical due diligence report and attachments,
La Costa Town Square project, City of Carlsbad, California, APN 223-050-73-00,
W.O. 8144-A-SC, dated February 9.
_____, 2022a, Geotechnical plan review, La Costa Town Square project, City of Carlsbad,
California, APN 223-050-73-00, W.O. 8144-A-SC, dated August 15.
GeoSoils, Inc.
_____, 2022b, Review and response to third party geotechnical review comments,
La Costa Town Square townhome site (APN 223-050-73-00), La Costa Boulevard,
City of Carlsbad, California, W.O. 8144-A-SC, dated March 24.
_____, 2021, Geotechnical due diligence evaluation of the La Costa Town Square
townhome site, APN 223-050-73-00, La Costa Avenue, City of Carlsbad, San Diego
County, California 92011, W.O. 8144-A-SC, dated June 17.
SB&O, Inc., 2024, Rough grading plans for, La Costa Town Square, 18 sheets,
scale 1"=40', P.N. CT 2017-0003, Delta 3 revision dated May 9.
True North Compliance Services, 2024, Plan review: retaining wall, La Costa Town Square,
Carlsbad CA, first review, 4 pgs., True North No. 24-018–197, dated March 24.
State of California, 2024, Civil Code, Sections 895 et seq.
Woodside 05S, LP Appendix A
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APPENDIX B
COPY OF GSI 2023E
GeoSoils, Inc.
Geotechnical C Geologic C Coastal C Environmental
5741 Palmer Way C Carlsbad, California 92010 C (760) 438-3155 C FAX (760) 931-0915 C www.geosoilsinc.com
M E M O R A N D U M
DATE: June 20, 2023 W.O. 8144-A-SC
Woodside 05S, LP
1250 Corona Pointe Court, Suite 500
Corona, California 92879
Attention: Mr. Craig Moreas
From: John P. Franklin, CEG 1340
Stephen J. Coover, GE 2057
SUBJECT: Geotechnical Update and Addendum to “Geotechnical Due Diligence Report
and Attachments, La Costa Town Square Project, City of Carlsbad, California
APN 223-050-73-00" W.O. 8144-A-SC, dated February 9, 2023
References: 1. ”Third- Party Geotechnical Review (First), La Costa Town Square Parcel 3, La Costa
Avenue, Carlsbad, California, GR2022-0001/CT2017-003, Project No. 9604.1, Log No. 21774,
dated February 9, 2022, by Hetherington Engineering, Inc.
2. “Review and Response to Third Party Geotechnical Review Comments, La Costa Town
Square Townhome Site, APN 223-050-73-00, La Costa Avenue, City of Carlsbad, San Diego
County, California,” W.O. 8144-A-SC, dated March 24, 2022, by GeoSoils, Inc.
3. “Geotechnical Due Diligence Evaluation of the La Costa Town Square Townhome Site,
APN 223-050-73-00, La Costa Avenue, City of Carlsbad, San Diego County, California
92011,” W.O. 8144-A-SC, dated June 17, 2021, by GeoSoils, Inc.
Pursuant to your request from the City, GeoSoils, Inc. (GSI), has prepared this update and addendum to the
subject documents with respect to the 2022 CBC. The scope of our services has included a review of the
referenced documents, analysis and date, and preparation of the geotechnical update and addendum.
Unless specifically superceded herein, the conclusions and recommendations in the referenced reports
remain pertinent and applicable, and should be appropriately implemented during planning, design, and
construction.
Based on our review, updated seismic design parameters are provided, below.
Seismic Shaking Parameters
Based on the site conditions, the following table summarizes the updated site-specific design criteria obtained
from the 2022 CBC (CBSC, 2022a), Chapter 16 Structural Design, Section 1613, Earthquake Loads. The
computer program “U.S. Seismic Design Maps, (https://seismicmaps.org/) provided by the Structural
Engineer’s Association of California and California Office of Statewide Health Planning (2023) was used for
design parameters. The short spectral response uses a period of 0.2 seconds.
•
GeoSoils, Inc.
2022 CBC SEISMIC DESIGN PARAMETERS
PARAMETER
SITE SPECIFIC
VALUE PER
ASCE 7-16
2022 CBC OR
REFERENCE
Risk Category I, II, or III Table 1604.5
Site Class C
Section 1613.2.2,
Chap. 20
ASCE 7-16
(p. 203-204)
Spectral Response - (0.2 sec), Ss 0.955g Section 1613.2.1
Figure 1613.2.1(1)
Spectral Response - (1 sec), S1 0.348 g Section 1613.2.1
Figure 1613.2.1(2)
Site Coefficient, Fa 1.2 Table 1613.2.3(1)
Site Coefficient, Fv
1.5
(Table11.4.2)ASCE 7-16)
Maximum Considered Earthquake Spectral
Response Acceleration
(0.2 sec), SMS
1.146 g Section 1613.2.3
(Eqn 16-36)
Maximum Considered Earthquake Spectral
Response Acceleration (1 sec), SM1
0.522 g
(Section 21.4)
Section 1613.2.3
(Eqn 16-37)
5% Damped Design Spectral Response
Acceleration (0.2 sec), SDS
0.764 g Section 1613.2.4
(Eqn 16-38)
5% Damped Design Spectral
Response Acceleration (1 sec), SD1
0.341 g
(Section 21.4)
Section 1613.2.4
(Eqn 16-39)
PGAM - Probabilistic Vertical Ground Acceleration
may be assumed as about 50% of these values. 0.5 g ASCE 7-16
(Eqn 11.8.1)
Seismic Design Category D
(Section 11.6)
Section 1613.2.5/
ASCE 7-16
(p. 85: Table 11.6-1
or 11.6-2)
GENERAL DESIGN PARAMETERS
PARAMETER VALUE
Distance to Seismic Source (Rose
Canyon)
±7.1 mi (11.4
km))*
Upper Bound Earthquake (Rose
Canyon)MW 7.2**
* Blake (2000a), **Cao, et al. (2003)
Woodside 05S, LP W.O. 8144-A-SC
La Costa Town Square, Carlsbad June 20, 2023
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GeoSoils, Inc.
Conformance to the criteria above for seismic design does not constitute any kind of guarantee or assurance
that significant structural damage or ground failure will not occur in the event of a large earthquake. The
primary goal of seismic design is to protect life, not to eliminate all damage, since such design may be
economically prohibitive. Cumulative effects of seismic events are not addressed in the 2022 CBC (CBSC,
2022a) and regular maintenance and repair following locally significant seismic events (i.e., Mw5.5) will likely
be necessary, as is the case in all of southern California.
Distribution:(1) Addressee (PDF via email)
Woodside 05S, LP W.O. 8144-A-SC
La Costa Town Square, Carlsbad June 20, 2023
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