HomeMy WebLinkAboutMS 2021-0004; ACACIA BEACH HOMES; FINAL SOILS REPORT; 2024-07-30
GEOTECHNICAL | ENVIRONMENTAL | MATERIALS
July 30, 2024
Project No. 3819-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, CA 92008
Attention: Mr. Clay Hatch
Subject: Final As Graded Geotechnical Report
Acacia Beach Homes Project
245 Acacia Avenue
Carlsbad, California
References: See Page 5
Dear Mr. Hatch:
We are pleased to present the results of our geotechnical testing and observation services
during post grading construction associated with the subject project.
Post grading construction has been performed on a periodic, on-call basis between the dates of
June 15th, 2023 to July 3rd, 2024. It is to the best of our knowledge that site post grading
presented in this report has been completed in general accordance with the approved
geotechnical reports (Hetherington, 2021 & GeoTek, 2022a, 2022b, 2022c &2023)) and As-
graded report for the site, applicable provisions of the California Building Code (CBC) and City
of Carlsbad guidelines.
This report provides a brief summary of site conditions observed during the post grading
construction for the subject site.
Rincon Homes July 30, 2024
Final As-Graded Compaction Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 2
SUMMARY OF GEOLOGIC AND SOILS CONDITIONS
Based on our field observations and testing during post grading site construction, we noted the
following:
▪ Visual classification of the soil in the field, compared to the soil description from
laboratory testing, was the basis for determining the maximum dry density value and
optimum moisture content applied to each soil density test.
▪ The backfill materials for sewer both onsite and offsite, were moisture conditioned to
near optimum moisture content and compacted to at least 90% of the maximum dry
density as determined by ASTM D 1557 test procedures.
▪ Residential building foundation footings were observed and qualitatively evaluated with a
soil probe to be firm and unyielding.
▪ Subgrade for subbase, aggregate base (AB) and asphalt concrete (AC) was observed and
tested to be at least 95% relative compaction for the offsite utility tie- ins and
improvements.
FIELD TESTING
Field density tests were taken at periodic intervals and random locations to verify the
compaction efforts by the grading contractor. The field density testing for the subject site was
performed using a portable nuclear gauge, in general accordance with testing procedure ASTM
D 6938.
LABORATORY TESTING
Moisture-Density Relationships
The laboratory maximum dry density and optimum moisture content for the soils were
determined in general accordance with test method ASTM D 1557. The table below presents
the soil type used for this project. The laboratory maximum density for asphalt concrete
mixtures was determined by the manufacturer plant laboratory.
Rincon Homes July 30, 2024
Final As-Graded Compaction Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 3
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY
AND OPTIMUM MOISTURE CONTENT TEST RESULTS (ASTM D 1557)
Soil Type Description
Optimum
Moisture
Content (%)
Maximum Dry
Density (pcf)
Maximum
Density (pcf)
HE-1 Brown Silty Sand 9.5 125.0
A Brown Gravely Silty Sand 7.5 126.0
CMB-1 Class II Miscellaneous Base 9.5 121.5
AC Asphalt - Concrete - - 144.1
CONCLUSIONS AND LIMITATIONS
The purpose of this report is to present a summary of observation and testing services
provided by this firm during post grading operations that were performed on the subject site.
Our observations were performed in such a manner as to be reasonably certain that the soils
tested are representative of the work, and that the work, in general, essentially complies with
the job requirements. Our services were performed in accordance with engineering principles
generally accepted at this time and in this area. No warranty 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.
Rincon Homes July 30, 2024
Final As-Graded Compaction Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 4
The opportunity to be of service is sincerely appreciated. If you should have any questions,
please do not hesitate to call our office.
Respectfully submitted,
GeoTek, Inc.
Christopher D. Livesey Edwin R. Cunningham
CEG 2733, Exp 05/31/25 RCE 81687, Exp 03/31/26
Vice President Project Engineer
Distribution: (1) Addressee via email
Attachments: Appendix A - Hetherington 2021, Geotechnical Investigation
Appendix B – GeoTek, 2022a, Interlocking Concrete Pavement
Appendix C – GeoTek, 2022b, Foundation Plan Review
Appendix D – GeoTek, 2022c, Response to Geotechnical Comments
Appendix E – GeoTek, 2023, As-Graded Report of Rough Grading
Figure 1 – Field Density Test Location Map
Table 1 – Summary Table of Field Density Tests Grading
Table 2 – Summary Table of Field Density Tests Retaining Wall
Table 3 – Summary Table of Field Density Tests Dry Utilities
Table 4 – Summary Table of Field Density Tests Sewer
Table 5 – Summary Table of Field Density Tests Asphalt
Table 6 – Summary Table of Field Density Tests Subgrade
Table 7 – Summary Table of Field Density Tests Aggregate Base
Rincon Homes July 30, 2024
Final As-Graded Compaction Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 5
SELECTED REFERENCES
GeoTek, Inc., 2022a, Interlocking Concrete Pavement, Acacia Beach Homes Project, 245 Acacia
Ave, Carlsbad, California, 92008, APN: 204-240-08-00, Project No, 3819-SD, dated
August 16, 2022.
, 2022b, Foundation Plan Review, Acacia Beach Homes Project, 245 Acacia Avenue,
Carlsbad, California, Project No, 3819-SD, dated September 7, 2022.
, 2022c, Response to Third-Party Geotechnical Review Comments, Proposed
Residential Development, 245 Acacia Avenue, Carlsbad, California, Project No, 3819-
SD, dated September 22, 2022.
, 2023, “As-Graded Report of Rough Grading, Acacia Beach Homes Project, 245 Acacia
Avenue, Carlsbad, California,” Project No. 3819-SD, dated July 7, 2023.
Hetherington Engineering, Inc., 2021, Geotechnical Investigation, Proposed Residential
Development, 245 Acacia Avenue, Carlsbad, California, Project No. 9324.1, Log No.
21510, dated June 21, 2021.
Pasco Lauret Suiter & Associates, 2023, “Grading Plans For: Acacia Beach Homes, 245 Acacia
Avenue,) Drawing No. 537, 7 sheets, dated February 28, 2023.
LEGEND
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - SEWER
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - ASPHALT
APPROXIMATE LOCATION OF
FIELD DENSITY TEST
– DRY UTILITIES
APPROXIMATE LOCATION OF
FIELD DENSITY TEST – BACKFILL
RETANING WALL
APPROXIMATE LIMITS OF GRADING
UNDER PURVIEW OF GEOTEK 2023
Figure 1
Field Density Test
Location Map
Rincon Homes
Acacia Homes
Carlsbad, California
GeoTek Project No. 3819-SD
1
LEGEND
ARTIFICIAL FILL PLACED UNDER THE
PURVIEW OF GEOTEK 2023
OLD PARALIC DEPOSITS CIRCLED
WHERE BURIED
APPROXIMATE LOCATION OF
REMOVAL BOTTOM
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - GRADING
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - SUBGRADE
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - BASE
3
376’
Qop
Af
R-4
2 3
4
56
7
8
910 11
12
13
14
1516
1718
1920,A
21 22 23
R-1
R-2R-3R-4
Af
Qop
49’49’
49’49’
2
1 1a
1
13
2
2
2
1
23
1
1
1
3
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-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
(%)
5/23/23 1 Northwest of Unit 1 51.0 9.8 112.7 HE-1 125.0 N 90
2 Northwest of Unit 1 52.0 9.9 113.1 HE-1 125.0 N 90
5/30/23 3 Unit 3 NW of Unit near Parking 51.0 7.8 110.7 HE-1 125.0 N 89
4 Retest of Number 3 51.0 6.9 115.4 HE-1 125.0 N 92
5 Unit 3 SE close to Apartments 49.5 7.4 115.5 HE-1 125.0 N 92
6 Unit 3 NW of Unit near Corner 49.5 7.1 113.2 HE-1 125.0 N 91
5/31/23 7 West of Unit 2 49.0 11.5 118.2 HE-1 125.0 N 95
8 West of Unit 2 49.0 8.5 113.9 HE-1 125.0 N 91
9 Northeast of Unit 3 49.0 10.7 126.5 HE-1 125.0 N 99
6/1/23 10 Unit 3 NE Corner 49.0 8.2 121.2 HE-1 125.0 N 97
11 Unit 3 Center of Lot 50.0 10.0 123.8 HE-1 125.0 N 99
12 Unit 3 SW Corner 50.0 7.2 112.3 HE-1 125.0 N 90
13 Unit 2 NE Corner 51.0 6.5 115.4 HE-1 125.0 N 92
14 Unit 2 North Middle 51.0 6.5 105.9 HE-1 125.0 N 95
15 Unit 2 West Corner 52.0 7.5 103.3 HE-1 125.0 N 93
16 Unit 2 Middle 52.0 7.8 121.2 HE-1 125.0 N 97
17 Unit 2 North Middle 51.0 8.2 118.5 HE-1 125.0 N 95
18 Unit 2 West Middle 52.0 8.4 124.7 HE-1 125.0 N 99
15A Re-test of Test 15 52.0 8.0 117.3 HE-1 125.0 N 94
16A Re-test of Test 16 52.0 7.2 118.2 HE-1 125.0 N 95
19 Near Entrance 52.0 7.2 118.2 HE-1 125.0 N 95
6/2/23 20 Unit 1 North facing Rd 52.0 6.4 105.8 HE-1 125.0 N 85
20A Retest of Number 20 52.0 6.8 113.9 HE-1 125.0 N 91
21 Unit 1 NorthEast facing Rd 52.0 6.2 112.6 HE-1 125.0 N 90
6/15/23 22 Unit 2 FG 7.5 121.3 A 126.0 N 96
23 Unit 3 FG 7.9 120.6 A 126.0 N 96
TABLE 1
SUMMARY OF FIELD DENSITY TESTS
Grading
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-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
(%)
6/27/23 R-1 West of wall near bush 52.0 6.9 125.6 I-1 126.0 N 99
R-2 South towards Center 52.0 4.8 124.2 I-1 126.0 N 99
R-3 Middle towards wall 57.0 6.2 123.9 I-1 126.0 N 98
R-4 Retest of Number 3 53.0 5.8 120.1 I-1 126.0 N 95
TABLE 2
SUMMARY OF FIELD DENSITY TESTS
Wall Backfill
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-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
(%)
10/13/23 1 Rinning perpendicular w/st near bldg SG 8.5 115.0 HE-1 125.0 N 92
TABLE 3
SUMMARY OF FIELD DENSITY TESTS
Dry Utilities
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-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
(%)
1 Sewage in section SG 7.6 116.0 HE-1 125.0 N 92
TABLE 4
SUMMARY OF FIELD DENSITY TESTS
Sewer
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-SD
DATE Test
No.Location Lot
No.
Sta
No.
Elev/
Depth
Moisture
Content
(%)
Total
Density
(pcf)
Soil
Type
Maximum
Density
(pcf)
Test
Type
Relative
Compaction
(%)
7/3/2024 1 Acaicia westbound lane AC -136.4 AC 144.1 N 95
7/3/2024 2 Acaicia westbound lane AC -138.2 AC 144.1 N 96
7/3/2024 3 Acaicia westbound lane AC -136.7 AC 144.1 N 95
TABLE 5
SUMMARY OF FIELD DENSITY TESTS
Asphalt
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-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
(%)
7/3/2024 1 Utility Tie-In to Acacia SG 9.5 117.0 HE-1 125.0 N 94
7/3/2024 1a Utility Tie-In to Acacia SG 9.5 118.1 HE-1 125.0 N 95
7/3/2024 2 Utility Tie-In to Acacia SG 9.5 119.0 HE-1 125.0 N 95
TABLE 6
SUMMARY OF FIELD DENSITY TESTS
Subgrade
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Rincon Homes
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Wall Backfill 7/25/2024
Project No.: 3819-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
(%)
7/3/2024 1 Utility Tie-In to Acacia AB 9.5 115.0 CMB-1 121.5 N 95
7/3/2024 2 Utility Tie-In to Acacia AB 9.5 116.0 CMB-1 121.5 N 96
7/3/2024 3 Utility Tie-In to Acacia AB 9.5 118.0 CMB-1 121.5 N 98
TABLE 7
SUMMARY OF FIELD DENSITY TESTS
Base
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
APPENDIX A
HETHERINGTON 2021, GEOTECHNICAL INVESTIGATION
APPENDIX B
GEOTEK, 2022a, INTERTOCKING CONCRETE PAVEMENT
GEOTECHNICAL | ENVIRONMENTAL | MATERIALS
August 16, 2022
Project No. 3819-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, CA 92008
Attention: Mr. Stuart Hatch
Subject: Intelocking Concrete Pavement
Acacia Beach Homes Project
245 Acacia Ave
Carlsbad, California, 92008
APN: 204-240-08-00
Dear Mr. Hatch,
As requested, by Bryan Knapp, Pasco Laret Suiter & Associates (PLSA), GeoTek, Inc. (GeoTek)
is providing Interlocking Concrete Pavement (ICP) recommendations for onsite driveways at the
subject site. Based on review of the “Geotechnical Investigation, 245 Acacia Avenue, Carlsbad,
California,” by Hetherington Engineering, Inc. (HEI) the following ICP recommendations are
provided.
The onsite subgrade soils consist of weathered paralic deposits, classified as silty sands (SM)
according to the boring logs in the above referenced report. A Traffic Index of 5 and an assumed
R-Value of 10 were used for design of the preliminary pavement section.
The final ICP section for the driveways should be based on R-Value testing of the finished
subgrade soils.
Impermeable interlocking concrete pavement should consist of 3 1/8-inch thick (minimum)
concrete pavers (with edge restraints and sand filled joints) underlain by bedding sand layer (for
leveling) and compacted base.
Materials for use as bedding sand and aggregate base should meet the following specifications in
Table - I:
Rincon Homes Project No. 3819-SD
Interlocking Concrete Pavement August 16, 2022
245 Acacia Ave Page 2
Carlsbad, California
Table - I
Material Layer Thickness Specification
Bedding Sand 1-inch ASTM No. 8 Stone
Aggregate Base 8-inches Caltrans Class 2
The aggregate base should be compacted to a minimum of 95-pecent of the maximum dry density
as determined by ASTM: D 1557. Prior to placement of aggregate base, the underlying subgrade
soils should be scarified to a depth of 12-inches and compacted to 95-percent relative
compaction.
The opportunity to be of service is sincerely appreciated. If you should have any questions, please
do not hesitate to call GeoTek
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
Distribution: (1) Addressee via email
Rincon Homes Project No. 3819-SD
Interlocking Concrete Pavement August 16, 2022
245 Acacia Ave Page 3
Carlsbad, California
REFERENCES
Hetherington Engineering, Inc., 2021, “Geotechnical Investigation,245 Acacia Avenue, Carlsbad,
California,” dated June21, 2021.
Interlocking Concrete Pavement Institute, 2014, “Tech Spec 4: Structural Design of Intelocking
Concrete Pavement for Roads and Parking Lots,” revised September 2014.
APPENDIX C
GEOTEK, 2022c, RESPONSE TO GEOTECHNICAL COMMENTS
GEOTECHNICAL | ENVIRONMENTAL | MATERIAL
September 22, 2022
Project No. 3819-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, California 92008
Attention: Mr. Tom St. Clair
Subject: Response to Third-Party Geotechnical Review Comments
Proposed Residential Development
245 Acacia Avenue
Carlsbad, California
Reference: See Page 6
Dear Mr. St. Clair:
As requested, by Bryan Knapp, Pasco Lauret Suiter & Associates (PLSA), GeoTek, Inc., (GeoTek)
has prepared this letter to provide a supplemental responds to City of Carlsbad third-party
review comments of the “Geotechnical Investigation, Proposed Residential Development, 245
Acacia Avenue, Carlsbad, California, Project No. 9324.1” by Hetherington Engineering, Inc. (HEI),
dated June 21, 2021 and “Grading Plans For: Acacia Beach Homes, 245 Acacia Avenue, Project
No. MS 2021-0004” by Pasco Laret Suiter & Associates, dated 2022 (sheets 1 through 7). Our
numbering corresponds to that used by the reviewer.
Review Comment No. 1
The Geotechnical Consultant should review the project grading and foundation plans and provide any
additional geotechnical recommendations, as appropriate, and indicate if the plans have been prepared
in accordance with the geotechnical recommendations provided in the referenced geotechnical report
(Hetherington Engineering, Inc., 2021).
Response to Review Comment No. 1
We have reviewed the project grading and foundation plans. The grading and foundation plans
have incorporated the geotechnical recommendations provided in the referenced geotechnical
report (Hetherington Engineering, Inc., 2021) and are considered suitable from a geotechnical
standpoint. The conclusions and recommendations provided in the geotechnical report
(Hetherington Engineering, Inc., 2021) remain applicable to the referenced grading and foundation
plans.
RINCON HOMES Project No. 3819-SD
Acacia Beach Homes September 22, 2022
245 Acacia Avenue, Carlsbad, California Page 2
Review Comment No. 2
The Geotechnical Consultant should provide a geotechnical cross-section(s) of the site or discussion as to
why one is not presented. If a geologic cross section is prepared, an updated geotechnical map/plot plan
showing the location of the cross-section should be provided.
Response to Review Comment No. 2
We have provided an updated geotechnical map/plot plan as Figure 1and a geologic cross section
as Figure 2.
Review Comment No. 3
The Geotechnical Consultant should provide a geotechnical map/plot plan to clearly show the limits of the
proposed structures and the lateral limits of the recommended remedial grading.
Response to Review Comment No. 3
A geotechnical map/plot plan is provided as Figure 1.
Review Comment No. 4
The Geotechnical Consultant should provide recommendations for import materials to be used for general
fill, retaining wall backfill, and utility trench backfill.
Response to Review Comment No. 4
Import fill should consist of granular soil with a “very low” to “low” expansion potential (EI of 50
or less) and free of deleterious material or rock larger than 6-inches. Import fill used as select
backfill for retaining walls should consist of granular soil with a “very low” expansion potential
(EI of less than 20) and free of deleterious material or rock larger than 6-inches. GeoTek should
be notified of the imported soil source and should be authorized to perform laboratory testing
of import soil prior to its arrival at the site to evaluate its suitability as fill.
Review Comment No. 5
The Geotechnical Consultant should provide recommendations for vehicular pavements.
Response to Review Comment No. 5
Traffic indices have not been provided during this stage of site planning. In addition, site
conditions have not been graded to a final design to evaluate specific pavement subgrade
conditions. Therefore, the minimum structural sections provided below are based on an assumed
R-Value of 10 and assumed traffic indices.
RINCON HOMES Project No. 3819-SD
Acacia Beach Homes September 22, 2022
245 Acacia Avenue, Carlsbad, California Page 3
PRELIMINARY ASPHALT PAVEMENT STRUCTURAL SECTION
Design Criteria Traffic Index
(TI)
Pavement Thickness
(inches)
Aggregate Base (AB)
Thickness (inches)
Driveway 5.0 4 7
Parking Stalls 4.0 4 6
Actual structural pavement design is to be determined by the geotechnical engineer’s testing (R-
Value) of the exposed subgrade.
It is anticipated that Portland Cement Concrete (PCC) pavements will be utilized. Based on the
City of Carlsbad minimum design guidelines for driveways, the following recommended minimum
PCC pavement section is provided for these areas:
PRELIMINARY PCC PAVEMENT STRUCTURAL SECTION
Design Criteria Traffic Index
(TI)
Pavement Thickness
(inches)
Aggregate Base (AB)
Thickness (inches)
Driveway 5.0 7 6
Parking Stalls 4.0 6 0
Interlocking concrete paver (ICP) section has been addressed in a separate “Interlocking
Concrete Paver” letter attached as Appendix A.
Review Comment No. 6
The Geotechnical Consultant should provide recommendations for exterior concrete flatwork.
Response to Review Comment No. 6
Exterior concrete flatwork should be designed using a four-inch minimum thickness with 6”x6”
– WI.4/WI.4 welded wire fabric, placed in the middle of slab. It is recommended that control
joints be placed in two directions spaced the numeric equivalent roughly 24 times the thickness
of the slab in inches (e.g., a 4-inch slab would have control joints at 96-inch [8-feet] centers).
These joints are a widely accepted means to control cracks and should be reviewed by the project
structural engineer. Some shrinkage and cracking of the concrete should be anticipated as a
result of typical mix designs and curing practices typically utilized in construction.
Presaturation of flatwork subgrade should be verified to be a minimum of 100% of the soils
optimum moisture to a depth of 12-inches for soils having a “very low” expansive index potential.
RINCON HOMES Project No. 3819-SD
Acacia Beach Homes September 22, 2022
245 Acacia Avenue, Carlsbad, California Page 4
Review Comment No. 7
The referenced grading plans (Pasco Lauret Suiter & Associates, 2022) depict the use of permeable
pavers for vehicular pavements. The Geotechnical Consultant should provide conclusions regarding the
suitability of using permeable pavers for vehicular pavements and recommendations for their design and
construction.
Response to Review Comment No. 7
Permeable pavers are not being utilized for this project at this time. Decorative concrete pavers
are part of the proposed project and recommendations have been provided in the “Interlocking
Concrete Pavement…” letter by GeoTek, dated August 16, 2022 and attached as Appendix A.
Review Comment No. 8
The Geotechnical Consultant should provide conclusions regarding the suitability of using of infiltration
devices such as the permeable pavers onsite.
Response to Review Comment No. 8
Permeable pavers are not being proposed for the project.
Review Comment No. 9
The referenced grading plans (Pasco Lauret Suiter & Associates, 2022) depict the structures being placed
in both cut and fill areas of the site. The Geotechnical Consultant should review the plans for areas of
potential cut/fill transitions beneath the buildings and provide recommendations to mitigate these
conditions, as appropriate.
Response to Review Comment No. 9
Grading may result in a cut/fill transition at the proposed building pad finish grades. If a geologic
contact of Formational material against fills is encountered at finish pad grades, the cut portion
should be over-excavated a minimum of three feet below pad grades, or two feet below the base
of proposed footings, whichever is deeper, and be replaced with engineered fill.
Review Comment No. 10
On Page 4 under “Seismic Effects – Ground Accelerations” and on Page 9 under References” of the
referenced geotechnical report (Hetherington Engineering, Inc., 2021) there are typos as the reports
refers to the 2016 California Building Code (CBC) and American Society of Civil Engineers (ASCE)
Publication 7-10 rather than 2019 and 2017 versions, respectively.
RINCON HOMES Project No. 3819-SD
Acacia Beach Homes September 22, 2022
245 Acacia Avenue, Carlsbad, California Page 5
Response to Review Comment No. 10
We concur that the above referenced documents CBC 2016 and ASCE publication 7-10 are
typos, and the correct referenced documents are CBC 2019 and ASCE publication 7-16. The
above comment is noted.
Review Comment No. 11
There are more recent geology maps available for the project vicinity. The Geotechnical Consultant should
review those and may consider updating their references, as appropriate.
Response to Review Comment No. 11
The above comment is noted.
Closure
Should you have any questions after reviewing this addendum, please feel free to contact our
office at your convenience.
Respectfully submitted,
GeoTek, Inc.
ENCLOSURES
Figure 1 – Geotechnical Map
Figure 2 – Cross-Section
Appendix A – Interlocking Concrete Paver Recommendations
Distribution: (1) Addressee Via Email
(1) PLSA – Bryan Knapp
Christopher D. Livesey
CEG, 2733 Exp. 05/31/23
Associate Vice President
Edwin R. Cunningham
RCE, 81687 Exp. 03/31/24
Project Engineer
RINCON HOMES Project No. 3819-SD
Acacia Beach Homes September 22, 2022
245 Acacia Avenue, Carlsbad, California Page 6
References
Hetherington Engineering, Inc., 2021, “Geotechnical Investigation, Proposed Residential
Development, 245 Acacia Avenue, Carlsbad, California,” dated June 21, 2021.
Ninyo & Moore, 2022, “Third-Party Geotechnical Review, Proposed Residential Development,
245 Acacia Avenue, Carlsbad, California,” dated June 24, 2022.
Pasco Lauret Suiter & Associates, 2022, “Preliminary Grading Plans For: Acacia Beach Homes,
245 Acacia Avenue,) 3 sheets, undated.
HE TP-1
HE TP-2
Qop
Qop
Qop
Qop Qop
A'A
Approximate Location and Orientation of
Test Pit
HE TP-2
Approximate Limits of Recommended Remedial Grading
Cross Section
Old Paralic DepositsQop
A A'
LEGEND
PN: 3819-SD
Figure 1
Geotechnical Map
1384 Poinsettia Avenue, Suite A
Vista, California 92081DATE: September 2022
Rincon Homes
245 Acacia Ave
Carlsbad, California
0 30 60
Scale: 1" = 30'
10
Appendix A
Interlocking Concrete Paver Recommendations
GEOTECHNICAL | ENVIRONMENTAL | MATERIALS
August 16, 2022
Project No. 3819-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, CA 92008
Attention: Mr. Stuart Hatch
Subject: Intelocking Concrete Pavement
Acacia Beach Homes Project
245 Acacia Ave
Carlsbad, California, 92008
APN: 204-240-08-00
Dear Mr. Hatch,
As requested, by Bryan Knapp, Pasco Laret Suiter & Associates (PLSA), GeoTek, Inc. (GeoTek)
is providing Interlocking Concrete Pavement (ICP) recommendations for onsite driveways at the
subject site. Based on review of the “Geotechnical Investigation, 245 Acacia Avenue, Carlsbad,
California,” by Hetherington Engineering, Inc. (HEI) the following ICP recommendations are
provided.
The onsite subgrade soils consist of weathered paralic deposits, classified as silty sands (SM)
according to the boring logs in the above referenced report. A Traffic Index of 5 and an assumed
R-Value of 10 were used for design of the preliminary pavement section.
The final ICP section for the driveways should be based on R-Value testing of the finished
subgrade soils.
Impermeable interlocking concrete pavement should consist of 3 1/8-inch thick (minimum)
concrete pavers (with edge restraints and sand filled joints) underlain by bedding sand layer (for
leveling) and compacted base.
Materials for use as bedding sand and aggregate base should meet the following specifications in
Table - I:
Rincon Homes Project No. 3819-SD
Interlocking Concrete Pavement August 16, 2022
245 Acacia Ave Page 2
Carlsbad, California
Table - I
Material Layer Thickness Specification
Bedding Sand 1-inch ASTM No. 8 Stone
Aggregate Base 8-inches Caltrans Class 2
The aggregate base should be compacted to a minimum of 95-pecent of the maximum dry density
as determined by ASTM: D 1557. Prior to placement of aggregate base, the underlying subgrade
soils should be scarified to a depth of 12-inches and compacted to 95-percent relative
compaction.
The opportunity to be of service is sincerely appreciated. If you should have any questions, please
do not hesitate to call GeoTek
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
Distribution: (1) Addressee via email
Rincon Homes Project No. 3819-SD
Interlocking Concrete Pavement August 16, 2022
245 Acacia Ave Page 3
Carlsbad, California
REFERENCES
Hetherington Engineering, Inc., 2021, “Geotechnical Investigation,245 Acacia Avenue, Carlsbad,
California,” dated June21, 2021.
Interlocking Concrete Pavement Institute, 2014, “Tech Spec 4: Structural Design of Intelocking
Concrete Pavement for Roads and Parking Lots,” revised September 2014.
APPENDIX D
GEOTEK, 2022b, FOUNDATION PLAN REVIEW
September 7, 2022
Project No.: 3819-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, CA 92008
Attention: Mr. Stuart Hatch
Subject: Foundation Plan Review
Acacia Beach Homes Project
245 Acacia Avenue
Carlsbad, California
Dear Mr. Hatch:
At the request of Mr. Patrick Kornman, Stephan Dalton Architects, this letter has been prepared
as a review of the proposed foundation plan. The purpose of this review was to form an opinion
of the geotechnical suitability of the plan to support the proposed improvements and for inclusion
of geotechnical design parameters provided in the “Geotechnical Investigation, Proposed
Residential Development…” 2021, by Hetherington Engineering, Inc. (HEI).
We have reviewed the Foundation plan, Structural Notes, and Structural Details prepared by
Gouvis Engineering Consulting Group, Inc., Sheets SN1A, SN1B, SN1C, SD1, S-1.1, and S-2.1
were reviewed. Based on our review of the foundation plans, they have been prepared in general
accordance with the geotechnical recommendations contained within the referenced report by
HEI.
RINCON HOMES September 7, 2022
Foundation Plan Review Project No.: 3819-SD
Acacia Beach Homes Project, Carlsbad, California Page 2
We appreciate 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 Edwin R. Cunningham
CEG 2733, Exp. 05/31/23 RCE 81687, Exp. 03/31/24
Associate Vice President Project Engineer
REFERENCES
Gouvis Engineering Consulting Group, Inc., 2022, Foundation Plan, Structural Notes, and
Structural Details for Acacia Beach Homes, dated August 22, 2022. (Sheets SN1A, SN1B,
SN1C, SD1, S-1.1, and S-2.1)
Hetherington Engineering, Inc., 2021, “Geotechnical Investigation, Proposed Residential
Development, 245 Acacia Avenue, Carlsbad, California,” dated June 21, 2021.
APPENDIX E
GEOTEK, 2023, AS-GRADED REPORT OF ROUGH GRADING
GEOTECHNICAL | ENVIRONMENTAL | MATERIALS
July 7, 2023
Project No. 3819-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, CA 92008
Attention: Mr. Stuart Hatch
Subject: As-Graded Report of Rough Grading
Acacia Beach Homes Project
245 Acacia Avenue
Carlsbad, California
Dear Mr. Hatch,
In accordance with your request, GeoTek, Inc. (GeoTek) is pleased to present the results of
geotechnical testing and grading observation services during earthwork construction associated
with the subject project.
Remedial grading has been completed under the observation of, and with selective testing by,
GeoTek between May 23, 2023 and June 28, 2023. To the best of GeoTek’s knowledge the
earthwork performed under the purview of this report has been completed in general accordance
with the approved geotechnical reports for the site, applicable provisions of the 2019 California
Building Code (CBC) and City of Carlsbad guidelines.
This letter provides a summary of site preparation and grading observed during the project
earthwork operations and results of field density (compaction) and moisture tests.
SUMMARY OF GEOLOGIC AND SOILS CONDITIONS
Based on our field observations and testing during the grading of the site, we note the following:
Rincon Homes July 7, 2023
As-Graded Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 2
Existing prior property improvements, vegetation, and deleterious materials were
removed within the limits of the earthwork construction and disposed of off-site prior to
grading of the building pads and interior driveway.
Removal bottoms exposed competent bedrock materials (Old Paralic deposits) as
anticipated by the Geotechnical Investigation prepared by Hetherington Engineering, Inc.
(HEI), 2021, and observed by a representative of GeoTek.
Remedial grading consisted of removal of prior fill, previous sewer utility lateral to the
property line, and weathered paralic deposits to a maximum depth of approximately
3-feet below existing subgrade.
Over-excavated lot was brought to design elevations with engineered fill.
Imported soil, consisting of very low expansive material was incorporated into the upper
foot of rough grades.
Visual classification of the soil in the field, compared to the soil description from
laboratory testing, was the basis for determining the maximum dry density value and
optimum moisture content applied to each soil density test.
Field density tests indicated the fill was placed and compacted to at least 90% and near
optimum moisture content relative to ASTM D 1557.
Retaining wall footing excavation was visually and qualitatively observed to be founded in
firm, unyielding, competent material.
Field density tests indicated the retaining wall backfill was placed and compacted to at
least 90% and near optimum moisture content relative to ASTM D 1557.
Field and Laboratory Testing
FIELD TESTING
Field density tests were taken at periodic intervals and random locations to check the
compaction efforts by the contractor’s performing compaction of fill. The field density testing
for the subject site was performed using a nuclear gauge, in general accordance with testing
procedure ASTM D 6938 for soils. The results of the field density testing conducted for the
herein reported site area are included in the attached Table 1 and presented on Figure 1.
LABORATORY TESTING
The laboratory maximum dry density and optimum moisture content for the soils were
determined in general accordance with test method ASTM D 1557. The table below presents
the soil type used for this project.
Rincon Homes July 7, 2023
As-Graded Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 3
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 (%)
HE-1 Brown Silty Sand 125.0 9.5
I-1* Dark grayish brown Gravelly
Silty Sand 126.0 7.5
*Import soil
Conclusions
Site grading has been completed in general accordance with the approved geotechnical report
(Hetherington Engineering, 2021), applicable provisions of the 2019 California Building Code
(CBC) and City of Carlsbad guidelines.
If a significant amount of time elapses between the grading and reprocessing reported as part of
this report and start of construction, building pad may require additional reprocessing. The
reprocessing should include moisture conditioning to a minimum content of optimum moisture
based on ASTM D1557 and to a depth of at least 12-inches prior to excavation of foundation
footings.
Limitations
The materials observed on the project site appear to be representative of the area; however, soil
and bedrock materials vary in character between excavations. Since our observations and test
results are based on the site conditions observed and encountered, and laboratory testing, our
conclusions are professional opinions are limited to the extent of the available data.
Cuts, fills and processing of existing fills under the purview of this report have been completed
under the observation of and with selective testing by GeoTek, Inc. and are found to be in
compliance with the Grading Ordinances of City of Carlsbad, California. Our findings were made,
and recommendations prepared in conformance with generally accepted professional engineering
practices and no further warranty is 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.
Rincon Homes July 7, 2023
As-Graded Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 4
The opportunity to be of service is sincerely appreciated. If you should have any questions, please
do not hesitate to call our office.
Respectfully submitted,
GeoTek, Inc.
Christopher D. Livesey Edwin R. Cunningham
CEG 2733, Exp. 05/31/25 RCE 81687, Exp. 03/31/24
Vice President Project Engineer
Distribution: (1) Addressee via email
Enclosures: Figure 1 – Field Density Test Location Map
Table 1 – Field Density Tests Grading
Table 2 – Field Density Tests Retaining Wall Backfill
Rincon Homes July 7, 2023
As-Graded Report Project No. 3819-SD
245 Acacia Avenue, Carlsbad, California Page 5
REFERENCES
GeoTek, Inc. 2022, Response to Third-Party Geotechnical Review Comments, Proposed
Residential Development, 245 Acacia Avenue, Carlsbad, California, Project No, 3819-SD,
dated September 22, 2022.
, 2022, Interlocking Concrete Pavement, Acacia Beach Homes Project, 245 Acacia Ave,
Carlsbad, California, 92008, APN: 204-240-08-00, Project No, 3819-SD, dated August 16,
2022.
, 2022, Foundation Plan Review, Acacia Beach Homes Project, 245 Acacia Avenue, Carlsbad,
California, Project No, 3819-SD, dated September 7, 2022.
Hetherington Engineering, Inc., 2021, Geotechnical Investigation, Proposed Residential
Development, 245 Acacia Avenue, Carlsbad, California, Project No. 9324.1, Log No.
21510, dated June 21, 2021.
Pasco Lauret Suiter & Associates, 2023, “Grading Plans For: Acacia Beach Homes, 245 Acacia
Avenue,) 7 sheets, dated February 28, 2023.
RINCON HOMES
245 Acacia Ave
Carlsbad, CA
GeoTek, Inc.
Grading 7/10/2023
Project No.: 3819-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
(%)
5/23/23 1 Northwest of Unit 1 51.0 9.8 112.7 HE-1 125.0 N 90
2 Northwest of Unit 1 52.0 9.9 113.1 HE-1 125.0 N 90
5/30/23 3 Unit 3 NW of Unit near Parking 51.0 7.8 110.7 HE-1 125.0 N 89
4 Unit 3 SW of Unit near Parking 51.0 6.9 115.4 HE-1 125.0 N 92
5 Unit 3 SE close to Apartments 49.5 7.4 115.5 HE-1 125.0 N 92
6 Unit 3 NW of Unit near Corner 49.5 7.1 113.2 HE-1 125.0 N 91
5/31/23 7 West of Unit 2 49.0 11.5 118.2 HE-1 125.0 N 95
8 West of Unit 2 49.0 8.5 113.9 HE-1 125.0 N 91
9 Northeast of Unit 3 49.0 10.7 126.5 HE-1 125.0 N 99
6/1/23 10 Unit 3 NE Corner 49.0 8.2 121.2 HE-1 125.0 N 97
11 Unit 3 Center of Lot 50.0 10.0 123.8 HE-1 125.0 N 99
12 Unit 3 SW Corner 50.0 7.2 112.3 HE-1 125.0 N 90
13 Unit 2 NE Corner 51.0 6.5 115.4 HE-1 125.0 N 92
14 Unit 2 North Middle 51.0 6.5 105.9 HE-1 125.0 N 95
15 Unit 2 West Corner 52.0 7.5 103.3 HE-1 125.0 N 93
16 Unit 2 Middle 52.0 7.8 121.2 HE-1 125.0 N 97
17 Unit 2 North Middle 51.0 8.2 118.5 HE-1 125.0 N 95
18 Unit 2 West Middle 52.0 8.4 124.7 HE-1 125.0 N 99
15A Re-test of Test 15 52.0 8.0 117.3 HE-1 125.0 N 94
16A Re-test of Test 16 52.0 7.2 118.2 HE-1 125.0 N 95
19 Near Entrance 52.0 7.2 118.2 HE-1 125.0 N 95
6/2/23 20 Unit 1 North facing Rd 52.0 6.4 105.8 HE-1 125.0 N 85
21 Unit 1 NorthEast facing Rd 52.0 6.2 111.6 HE-1 125.0 N 90
6/15/23 22 Unit 2 FG 7.5 121.3 A 126.0 N 96
23 Unit 3 FG 7.9 120.6 A 126.0 N 96
TABLE 1
SUMMARY OF FIELD DENSITY TESTS
Grading
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
NAME IN CAPS ITALICS.
Job Name
Location, CA
GeoTek, Inc.
Wall Backfill 7/10/2023
Project No.: 3 -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
(%)
6/27/23 1 West of wall near bush 52.0 6.9 125.6 I-1 126.0 N 99
2 South towards Center 52.0 4.8 124.2 I-1 126.0 N 99
3 Middle towards wall 57.0 6.2 123.9 I-1 126.0 N 98
4 Near wall towards North 53.0 5.8 120.1 I-1 126.0 N 95
SUMMARY OF FIELD DENSITY TESTS
Wall Backfill
Note:
N = Nuclear Guage Test
FG = Finished Grade Test
All elevations are approximate
Figure 1
Field Density Test
Location Map
Rincon Homes
Acacia Homes
Carlsbad, California
GeoTek Project No. 3819-SD
1
LEGEND
ARTIFICIAL FILL PLACED UNDER THE
PURVIEW OF THIS REPORT
OLD PARALIC DEPOSITS CIRCLED
WHERE BURIED
APPROXIMATE LOCATION OF
REMOVAL BOTTOM
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - GRADING
APPROXIMATE LOCATION OF
FIELD DENSITY TEST - WALL
APPROXIMATE LIMITS OF GRADING
UNDER PURVIEW OF THIS REPORT
23
376’
Qop
Af
R-4
2 3
4
5
6
7
8
910 11
12
13
14
1516
1718
19
20
21
22 23
R-1
R-2R-3R-4
Af
Qop
49’49’
49’49’