HomeMy WebLinkAboutCDP 2020-0007; TERRA BELLA DEVELOPMENT; FINAL SOILS REPORT; 2022-11-10
November 10, 2022
Project No. 3630-SD
Terra Bella Development, LLC
P.O. Box 232458
Encinitas, California 920243
Attention: Ms. Meng Xu
Subject: Final Geotechnical Report
Construction Observation & Testing
6479 Surfside Lane
Carlsbad, California
Dear Ms. Xu:
GeoTek, Inc. (GeoTek) is pleased to present the results of geotechnical testing and observation
services conducted during construction of the subject project. This report summarizes the
completion of the basement excavation, foundation excavations, and retaining wall backfill, as
observed and with selective compaction testing by GeoTek, Inc.
GEOLOGIC CONDITIONS
Subsurface conditions encountered during construction were consistent with those described in
the “Preliminary Geotechnical Evaluation…” by Geotek (2019) and the “Building Pad
Geotechnical Certification…” letter by GeoTek (2021). No groundwater was encountered.
FOUNDATION EXCAVATIONS
Foundation excavations for the residential structure and basement retaining walls were observed
by personnel from this office. Footing excavations were founded into approved paralic deposits
as recommended by the ”Preliminary Geotechnical Evaluation…” by GeoTek (2019).
FIELD AND LABORATORY TESTING
FIELD TESTING
Field density (compaction) testing was performed at basement pad grade and placement of
retaining wall backfill for basement retaining walls. Field density tests were taken at periodic
GeoTek, Inc.
1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505
(760) 599-0509 Of" :e (760) 599-0593 Fa:.... www.geotekusa.com
GEOTEK
TERRA BELLA, LLC Project No. 3630-SD
Final Geotechnical Report November 10, 2022
6479 Surfside Lane, Carlsbad, California Page 2
intervals and random locations to check the compaction efforts by the contractor. The field
density testing for the subject areas was performed using a nuclear gauge, in general accordance
with ASTM D 6938 test procedures.
The results of field density testing performed under the testing of GeoTek and conducted for the
subject area(s) are included in the attached Table 1. The approximate locations of the field
density tests are shown on the enclosed Field Density Test Location Map (Figure 1).
LABORATORY TESTING
Moisture-Density Relationships
The laboratory maximum dry density and optimum moisture content for the soils utilized during
the project grading operations were determined in general accordance with ASTM D 1557 test
procedures. Table A below presents the test results.
TABLE 1
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY
AND OPTIMUM MOISTURE CONTENT TEST RESULTS (ASTM D 1557)
Soil Type Description Maximum Dry
Density (pcf)
Optimum Moisture
Content (%)
A Brown Silty Sand 130.5 7.5
CONCLUSIONS
Based on the field density tests, a minimum relative compaction of 90 percent of the laboratory
standard (ASTM D 1557) was achieved at the locations tested. The results of field density and
retaining wall backfill testing performed by GeoTek for the subject project are included in the
attached Table 1. The approximate locations of the field density and retaining wall tests are
shown on the enclosed Density Test Location Map (Figure 1).
LIMITATIONS
The purpose of this report is to present a summary of geotechnical observation and testing
services provided by GeoTek during construction operations and is limited to the basement
foundation observation and basement retaining wall backfill observation and testing, that were
performed on the subject property between July 29 and September 24, 2021.
GEOTEK
TERRA BELLA, LLC Project No. 3630-SD
Final Geotechnical Report November 10, 2022
6479 Surfside Lane, Carlsbad, California Page 3
Preparation for, and placement of, compacted fill was monitored by representatives of GeoTek
on an on-call, part-time, basis. All soils tested were found to meet or exceed the minimum
degree of compaction specified in the job requirements. Field density tests were performed at
random locations throughout the area of the job that is within the scope of this report. GeoTek’s
observations and tests were performed in such a manner as to be reasonably ascertain that the
soils tested are representative of the work, and that the work, in general, essentially complies
with the job requirements. GeoTek’s services were performed in accordance with engineering
principles generally accepted at this time and in this area. No warranty is expressed or implied.
It should be understood that field data, including density test locations and elevations, as well as
the location of compacted fill, are only approximately located. The accuracy of the field
technician's estimated locations will vary depending on the survey control available at the time
the estimations were made. No warranty as to the actual extent of the filled area, nor of its
relationship to any planned structural improvements, is expressed or implied.
This report is subject to review by the controlling authorities for this project. GeoTek accepts
neither responsibility nor liability for work, testing, or recommendations performed or provided
by others.
GeoTek appreciates the opportunity to be of service on this project. Please contact the
undersigned if you have any questions.
Respectfully submitted,
GeoTek, Inc
Christopher D. Livesey
CEG 2733, Exp. 05/31/23
Associate Vice President
Edwin R. Cunningham
RCE 81687, Exp. 03/31/24
Project Engineer
Enclosures: Table 1 – Summary of Field Density Tests
Figure 1 – Compaction Map
Distribution: (1) Addressee
GEOTEK
TERRA BELLA, LLC Project No. 3630-SD
Final Geotechnical Report November 10, 2022
6479 Surfside Lane, Carlsbad, California Page 4
REFERERANCES
GeoTek, Inc, 2019, “Preliminary Geotechnical Evaluation, 6479 Surfside Lane, Carlsbad,
California”, dated March 9, 2019.
____, 2021, “Building Pad Geotechnical Certification, 6479 Surfside Lane, Carlsbad,
California”, dated July 30, 2021.
HWL Planning & Engineering, 2020, Preliminary Grading Plan for 6479 Surfside Lane,
Carlsbad, CA 92011, 1 Sheet, plot dated March 5, 2020.
Mercado Associates, Inc., 2021, Structural Plans for 6479 Surfside Lane, Carlsbad,
California, dated February 26, 2021.
GEOTEK
1
2
3
4
1
60'
5
2 Approximate Location of Field Density
Compaction Tests
Approximate Location of Retaining Wall
Compaction Test
2
Approximate Limits of Grading
60'Approximate Excavation Bottom
Elevation (MSL)
LEGEND
5
1384 Poinsettia Avenue, Suite A
Vista, California 92081
N
Figure 1
Field Density Test Location Map
Plan adapted from "Grading Plan" by
HWL Planning & Engineering
DATE: November 2022
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Scale: 1" = 10'
Terra Bella Development LLC
6479 Surfside Lane
Carlsbad, California
PN: 3630-SD
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TERRA BELLA DEVELOPMENT, LLC
6479 Surfside Lane
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 11/10/2022
Project No.: 3630-SD
DATE Test
No.Location Lot
No.
Sta
No.
Elev/
Depth
Moisture
Content
(%)
Dry
Density
(pcf)
Soil
Type
Maximum
Density
(pcf)
Test
Type
Relative
Compaction
(%)
9/29/21 1 East Wall TW-6' 8.5 118.8 A 130.5 N 91
2 Northeast Wall TW-6' 14.5 117.0 A 130.5 N 90
9/30/21 3 North side of Wall TW-5' 8.9 123.5 A 130.5 N 95
4 East side of Wall TW-5' 8.3 121.2 A 130.5 N 93
5 Northeast corner of Wall TW-5' 8.7 122.4 A 130.5 N 94
TABLE 1
SUMMARY OF FIELD DENSITY TESTS
Wall Backfill
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
TW = Top of Wall
TERRA BELLA DEVELOPMENT, LLC
6479 Surfside Lane
Carlsbad, CA
GeoTek, Inc.
Basement 11/10/2022
Project No.: 3630 -SD
DATE Test
No.Location Lot
No.
Sta
No.
Elev/
Depth
Moisture
Content
(%)
Dry
Density
(pcf)
Soil
Type
Maximum
Density
(pcf)
Test
Type
Relative
Compaction
(%)
7/29/21 1 Northside Basement Bottom 60.0 12.3 118.1 A 130.5 N 91
2 Southside Basement Bottom 60.0 14.5 116.9 A 130.5 N 90
TABLE 1
SUMMARY OF FIELD DENSITY TESTS
Basement
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate