HomeMy WebLinkAboutCT 2017-0003; LA COSTA TOWN SQUARE PARCEL 3 RESIDENTIAL; REVIEW OF CONSTRUCTION CHANGE NO. 2 ROUGH GRADING PLANS; 2023-08-01•
Geotechnical • Geologic • Coastal • Environmental
5741 Palmer Way • Carlsbad, California 9201 0 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com
DATE:
TO:
ATTENTION:
FRO M:
SUBJECT:
MEMORANDUM
August 1, 2023
Woodsid e 05S, LP
1250 Corona Pointe Court, Suite 500
Corona, California 92879
Mr. Craig Moraes
John P. Franklin, CEG 1340
Stephen J. Coover, GE 2057
W.O. 8144-B-SC
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
In accordance with your request, GeoSoils, Inc. (GSI) has reviewed the construction change no.
2 rough grading plans prepared by SB&O, Inc. ([SB&O], 2023 [see the Appendix]). The purpose
of our review was to evaluate if the preliminary geotechnical recommendations contained in the
project geotechnical reports and memoranda, prepared by this firm and referenced in the
Appendix, were properly incorporated into SB&O (2023). GS l's scope of services included reviews
of the referenced documents, engineering and geologic analyses, and the preparation of this
memorandum. Unless specifically superseded in the text of this memorandum, GS l's conclusions
and recommendations included in the project geotechnical reports and memoranda, referenced
in the Appendix, remain valid and applicable.
Based on our review, it is our opinion that SB&O (2023) satisfactorily incorporates the preliminary
geotechnical recommendations provided in the project geotechnical reports and memoranda,
referenced in the Appendix. However, SB&O (2023) does not currently show slurry backfill of the
portions of the trenches for Segment Nos. 1 and 3 of Storm Drain Line 8, where they pass beneath
the planned San Diego Regional Standard (SDRSD) C-4 and C-6 retaining walls, as recommended
in GSI (2023c). For convenience, GSI (2023c) is provided in the Appendix, following the
references. Provided that the underground utility installer is made aware of the recommended
placement of slurry backfill within these storm drain trenches, it is the opinion of GSI that
SB&O (2023) does not require further revision in this regard. Should any additional changes be
made to SB&O (2023) that involve the geotechnical aspects of the subject project, following the
issuance of this memorandum, GSI should be provided with the opportunity to review the amended
plans prior to the implementation of the work.
The conclusions and recommendations presented herein are professional op1n1ons. These
opinions have been derived in accordance with current standards of practice, and no warranty is
express or implied. 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 . In addition, this report may be subject to review by the controlling
authorities.
Enclosure: Appendix -References and GSI {2023c}
Distribution: (1) Addressee (PDF via email)
Woodside 055, LP
La Costa Town Square, Carlsbad
File:e:\wp21\8100\8144b.roc2.mem GeoSoils, Inc.
W.O. 8144-B-SC
August 1, 2023
Page 2
APPENDIX
REFERENCES
GeoSoils, Inc., 2023a, Standalone geotechnical report and response to City of Carlsbad
Geotechnical Review Memorandum dated July 7, 2023, proposed repairs to 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-B-SC, dated July 12.
__ , 2023b, Memorandum: Geotechnical review of post tension plans, La Costa Town Square
affordable project, City of Carlsbad, California APN 223-050-73-00, W. 0. 8144-A-SC, dated
July 10.
__ , 2023c, Memorandum: Review of construction change rough 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 June 29.
__ , 2023d, 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.
, 2023e, Memorandum: Geotechnical recommendations for subdrain construction north of
planned building pads tor Lots 6 through 16 and Private Driveways "C" through "H", 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.
__ , 2023f, Memorandum: Review of precise grading plans, La Costa Town Square project, City
of Carlsbad, CaliforniaAPN 223-050-73-00, project no.: CT2017-0003, 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.
__ , 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 town home 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. 2023, Rough grading plans for: La Costa Town Square," 15 sheets, various scales,
project no.: CT 2017-0003, drawing no.: 536-1A, construction change 2 plan set dated
July 28.
GeoSoils, Inc.
•
Geotechnical •Geologic• Coastal• Environmental
5741 Palmer Way • Carlsbad , California 9201 O • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com
DATE:
TO:
ATTENTION:
FROM:
SUBJECT:
REFERENCES:
MEMORANDUM
June 29, 2023
Woodside 05S, LP
1250 Corona Pointe Court, Suite 500
Corona, California 92879 ---------
Mr. Craig Moraes
John P. Franklin, CEG 1340
Stephen J. Coover, GE 2057
W.O. 8144-B-SC
Review of Construction Change Rough 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
1. "Rough Grading Plans for: La Costa Town Square," 14 sheets, various scales,
Project No.: CT 2017-0003, Drawing No.: 536-1A, Construction Change Plan Set
dated June 29, 2023, by SB&O, Inc.
2. "Geotechnical Recommendations for Subdrain Construction North of Planned
Building Pads for Lots 6 through 16 and Private Driveways 'C' Through 'H', 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, 2023, by
GeoSoils, Inc.
3. "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, 2023, by GeoSoils, Inc.
4. "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 July 21, 2021, by GeoSoils, Inc.
In accordance with your request, GeoSoils, Inc. (GSI) has reviewed the construction change rough
grading plans, notes, and details prepared by SB&O, Inc., including the proposed repair plan to
existing Anchor Retaining Wall No. 1 (see Reference No. 1). The purpose of our review was to
evaluate if the preliminary geotechnical recommendations contained in References 2 through 4
. were properly incorporated into Reference 1. GSl's scope of services included reviews of the
referenced documents, engineering and geologic analysis, and preparation of this memorandum.
Unless specifically superseded in the text of this memorandum, the conclusions and
recommendations presented in References 2 through 4, remain valid and applicable.
Based on our review, it is our opinion that Reference 1 has properly incorporated the preliminary
geotechnical recommendations provided in References 2 through 4. In order to move the
proposed subdrain construction further south of the face of the existing Anchor Retaining Wall
No. 1, and to reduce the depth of the northern perimeter grade beams for planned Buildings
5 through 16, this is required to penetrate the 0.5:1 (horizontal:vertical [h:v]) plane projected up
and toward the buildings from the springline of the 8-inch diameter perforated subdrain pipe, the
horizontal separation between the perforated subdrain pipe and the associated trench sidewalls
may be reduced to 3 inches. This reduced horizontal separation may be implemented on the
cond ition the maximum dimension of the subdrain gravel does not exceed 1 ½ inches. Additionally,
as an alternative to deepening the northern perimeter grade beams for Buildings 5 through 16, the
grade beams may be constructed as shown on the final post-tensioned slab foundation plans and
cast upon cured 1 .5-to 2-sack sand-cement slurry with a width that is equivalent to that of the
perimeter grade beam and that penetrates the aforementioned plane. The waterproofing shown
in Detail A4 of Reference 1 should extend a few inches below the contact between the grade beam
concrete and the slurry. Lastly, where Segment Nos. 1 and 3 of Storm Drain Line 8 pass beneath
the planned San Diego Regional Standard (SDRSD) C-4 and C-6 retaining walls, as shown in
Detail C11 , the storm drain trench should be backfilled with a 1-sack sand-cement slurry. The
slurry backfill should extend a minimum horizontal distance of 5 feet beyond the wall foundation
where it is transected by the storm drain line (in plan view). Should any additional revisions be
made to Reference 1 that involve the geotechnical aspects of the subject project, following the
issuance of this memorandum, GSI should be provided with the opportunity to review the amended
plans prior to the implementation of the work.
The conclusions and recommendations presented herein are professional opinions. These
opinions have been derived in accordance with current standards of practice, and no warranty is
express or implied. 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. In addition, this report may be subject to review by the controlling
authorities.
Distribution: (1) Addressee (PDF via email)
Woodside 05S, LP
APN 223-050-73-00, Carlsbad
File:e:\wp21 \8100\8144b.roc.mem GeoSoils, Inc.
W.O. 8144-B-SC
June 29, 2023
Page 2