HomeMy WebLinkAboutCDP 2020-0017; SAREM RESIDENCE; FINAL SOILS REPORT; 2023-08-10
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For more information visit us online at www.petra-inc.com
August 10, 2023 J.N. 20-155
Revision 4
MR. SCOTT SAREM 5796 Armada Drive, Suite 375 Carlsbad, California 92008
Subject: Revised Final Geotechnical Report, Proposed Two-Story Residence, 4005 Skyline
Road, City of Carlsbad, San Diego County, California References: See Attached List
Dear Mr. Sarem:
In accordance with the request of Mr. Jeff Piva, project superintendent, Petra Geosciences, Inc. (Petra)
has prepared this revised final geotechnical report of grading for 4005 Skyline Road, Permit
#GR2021-0016, located on the west side of Skyline Road and northerly of Tamarack Avenue in the city of
Carlsbad, San Diego County, California.
The purpose of this report is to document that the grading for the Sarem property has been completed in
conformance with the recommendations of the project geotechnical reports (references) and that the fill
materials have been properly placed and compacted in accordance with the project geotechnical reports
(referenced) and the City of Carlsbad Grading Ordinance.
GEOLOGIC CONDITIONS Upon completion of the grading, representative samples were taken from the building areas prior to
construction of the foundations for expansion testing and chemical analysis. Subsurface geologic conditions
were consistent with those reports listed in the attached References.
SUMMARY OF OBSERVATIONS AND TESTING
Rough Grading
The rough grading and post grading was performed between October 2021 and September 2022 with
geotechnical observation and testing provided by Petra Geosciences, Inc. Prior to fill placement, the existing
building and site vegetation were stripped and removed from the site. In areas to receive engineered fill,
low-density surficial soils, which generally consisted of undocumented artificial fill, residual topsoil, and
the upper portions of the paralic deposits were removed to expose competent paralic deposits, as determined
I
PETRA SOLID AS A ROCK
GEOSCIENCES1"0
MR. SCOTT SAREM August 10, 2023
4005 Skyline Drive / Carlsbad J.N. 20-155 Revision 4 Page 2
by representatives from Petra, including periodic observations by a Petra geologist. The removal depths of
native site soils were on the order of 1 to 3 feet below the original ground surface. Building pad was over-
excavated a minimum of 3 feet below pad grade. The elevations of removal and over-excavation bottoms
were obtained during grading with the grading contractor’s GPS system.
Following removals and over- excavation, the exposed bottom surfaces were scarified approximately 1 foot
in depth, moisture-conditioned, as needed to achieve above optimum moisture conditions, and then re-
compacted in-place to no less than 95 percent relative compaction below the building pad and 90 percent
relative compaction in other areas by track walking with a D-6 dozer and wheel-rolling with other heavy
construction equipment. Field density and moisture content tests were performed in accordance with
ASTM D 6938 (nuclear gauge method). The limits of site grading, grading bottom cleanout elevations, and
field density test locations are shown on the attached, Figure 1. The results of the field density tests are
included in Table I. We tested laboratory samples used for fill to evaluate moisture-density relationships,
optimum moisture content and maximum dry density (ASTM D 1557). In addition, we obtained soil
samples at finish grade to evaluate expansion potential (ASTM D 4829), water soluble sulfate content
(California Test No. 417), water soluble chloride (California Test No. 422), and pH/resistivity (California
Test No. 643). The laboratory test results are included in Appendix A.
Fill Slopes
The interior fill slopes were constructed at an inclination of 2:1 (h:v) to heights of approximately 8 feet or
less. The fill slopes were built a few feet thick and trimmed back to the compacted core. The fill slopes are
considered to be both grossly and surficially stable to the heights and inclinations at which they are
constructed.
Foundation Excavations
Foundation excavations for the site retaining walls and the residence were observed by this office at the
time that they were excavated. Site retaining wall foundations were per County of San Diego standard
details and are called out on the Grading Plans by Toal Engineering (Toal, 2022). The residence foundation
were designed by NS Structural Engineering (NSSE, 2020). All foundations were observed to be embedded
in compacted fill soils placed during site grading and retaining wall backfilling operations, as
recommended.
~PETRA ~ GEOSCIENCES"'~ SOLID AS A ROCK
MR. SCOTT SAREM August 10, 2023
4005 Skyline Drive / Carlsbad J.N. 20-155 Revision 4 Page 3
Retaining Wall Backdrains/Backfill
Limited observation and testing of retaining wall backfill and observation of backdrains were performed
by this office on a part time basis, as requested by the general contractor. Retaining walls were generally
provided with a MiraDRAIN and J-drain type back drainage systems. We were not requested and did not
observe ultimate drainage connections. A back drain was not installed behind the pickleball court retaining
wall at contractors’ convenience. The retaining walls were backfilled with onsite granular soils. Field
density testing and representative probing was performed in the retaining wall backfill to document that 90
percent or more relative compaction was achieved and that the backfill was firm and unyielding. During
the course of backfilling, when field density tests indicated a relative compaction of less than the required
density or low moisture conditions, the soil was reworked in-place and then retested until the appropriate
results were achieved. The field density test locations are plotted on Figure 1. The results of the density
tests are included in Table I. Maximum Density/Optimum moisture determinations are included in Figure 1
and Appendix A.
Utility Trench Backfill
Limited observation and testing of utility trench backfill was performed on a part time basis as requested
by the general contractor. Field density testing was performed to document that the building pad area and
surrounding areas/wall backfill soils exhibited 90 percent or more relative compaction. During the course
of backfilling where field density tests indicated a relative compaction of less than the required density or
low moisture conditions, the soil was reworked in-place and then retested until the appropriate results were
achieved. The field density tests are included as Table I and the test locations are plotted on Figure 1. Based
on Petra’s field observations and in-situ density testing, the subject building pad is deemed suitable for the
intended use.
Hardscape Subgrades Limited observation and testing of hardscape subgrade was performed on a part time basis as requested by
the general contractor. Field density testing was performed to document that the areas of proposed
hardscape improvements soils exhibited 90 percent or more relative compaction. During the course of
backfilling when field density tests indicated a relative compaction of less than the required density or low
moisture conditions, the soil was reworked in-place and then retested until the appropriate results were
achieved. The field density tests are included as Table I and the test locations are plotted on Figure 1. Based
~PETRA ~ GEOSCIENCES"'~ SOLID AS A ROCK
MR. SCOTT SAREM August 10, 2023
4005 Skyline Drive / Carlsbad J.N. 20-155 Revision 4 Page 4
on Petra’s field observations and in-situ density testing, the subject building pad is deemed suitable for the
intended use.
Swimming Pool Petra was not requested and did not observe or test the swimming pool excavation or any additional grading
that was performed as a part of its construction. Consequently, Petra cannot provide any comment on its
suitability from a geotechnical standpoint.
CONCLUSIONS
The geotechnical elements observed and tested by this office have been completed in compliance with the
grading codes of the City of Carlsbad and with the recommendations presented in the referenced
geotechnical reports prepared by Petra.
A representative of Petra was present on-site on an on-call basis for the purpose of providing the owner's
representative with professional opinions and recommendations. These opinions and recommendations
were developed based on field observations and selective testing of the contractor's work. Our scope of
services during this project did not include supervision or direction of the contractor, his personnel, or his
subcontractors. Our observations and testing did not reveal any obvious deviations from the
recommendations provided in the referenced geotechnical reports by our firm; however, Petra does not in
any way guarantee the contractor's work, nor do our services relieve the contractor (or any subcontractors)
of their liability should any defects subsequently be discovered in their work product.
Based on our findings, the conclusions and recommendations presented herein and within the referenced
report by our firm were prepared in conformance with generally accepted professional engineering
practices. No warranty is expressed or implied.
~PETRA ~ GEOSCIENCES"'~ SOLID AS A ROCK
MR. SCOTT SAREM August 10, 2023
4005 Skyline Drive / Carlsbad J.N. 20-155 Revision 4 Page 5
It has been a pleasure to be of service to you on this project. Should you have questions regarding the
contents of this report or should you require additional information, please contact this office.
Respectfully submitted,
PETRA GEOSCIENCES, INC.
8/10/23
Jim Larwood Grayson R. Walker Principal Geologist Principal Engineer CEG 1897 GE 871 JL/GRW/lv Attachments: References Table I – Field Density Test Results
Figure 1 – Density Test Location Map Appendix A – Laboratory Test Data
Distribution: (1) Addressee (1) Mr. Nick Deletto (City of Carlsbad) (1) Mr. Jeff Piva
(1) Mr. Mark Browe (1) Mr. Caleb Rios
W:\2020-2025\2020\100\20-155\Reports\20-155 300 4th Revised Final Geotechnical Report.docx
~PETRA ~ GEOSCIENCES"'~ SOLID AS A ROCK
MR. SCOTT SAREM August 10, 2023
4005 Skyline Drive / Carlsbad J.N. 20-155 Revision 4 Page 24
REFERENCES
NS Structural Engineering, Inc., 2020, Foundation Plan for Sarem Residence, 4005 Skyline Road, Carlsbad, dated October 8.
Petra Geosciences, Inc., 2020a, Preliminary Geotechnical Evaluation, Proposed Two-Story Residence,4005Skyline Road, APN 207-072-17-00, City of Carlsbad, San Diego County, California, J.N. 18-308, dated May 11. ______, 2020b, Geotechnical Commentary on Soil Infiltration Characteristics, Proposed Two-Story Residence, 4005 Skyline Road, City of Carlsbad, San Diego County, California, J.N. 20-155, dated May 28. , 2020c, Geotechnical Review of Grading and Foundation Plans, Proposed Two-Story Residence, 4005 Skyline Road, City of Carlsbad, San Diego County, California, J.N. 20-155, dated October 20. Toal Engineering, Inc., 2022, Grading Plans for Sarem Residence (4005 Skyline Road) GR2021-0016, Sheets 2, 4 and 5, dated February 3.
~PETRA ~ GEOSCIENCES"'~ SOLID AS A ROCK
TABLE 1
Field Density Test Results
Test
Date
Test
No.Test Location Elev.
Soil
Type
Test
Type*
Rel.
Comp.
Proj.
Spec.
Pass/
Fail
(ft)Opt.Field Max.Field (%)(%)(P/F)
10/27/2021 1 Sports CourtSouthwest corner 273.0 1 10.0 9.6 124.0 115.5 N 93 90.0 P
10/27/2021 2 Sport CourtSouthwest corner 273.0 1 10.0 9.3 124.0 117.6 N 94 90.0 P
10/28/2021 3 Sport CourtCenter 274.0 1 10.0 8.0 124.0 114.9 N 92 90.0 P
10/28/2021 4 Retest # 3 274.0 1 10.0 9.9 124.0 119.5 N 96 90.0 P
10/29/2021 5 Northwest corner 20’ east of the center of the biofiltration area 277.0 1 10.0 8.6 124.0 115.9 N 93 90.0 P
10/29/2021 6 North side center of sport court 275.0 1 10.0 10.4 124.0 112.2 N 90 90.0 P
10/29/2021 7 Retest # 5 277.0 1 10.0 10.5 124.0 115.3 N 92 90.0 P
10/29/2021 8 Proposed pool center 278.0 1 10.0 10.7 124.0 116.1 N 93 90.0 P
11/01/2021 9 South west side of proposed pool area 280.0 1 10.0 10.9 124.0 114.1 N 92 90.0 P
11/02/2021 10 South east side of proposed pool area 282.0 1 10.0 10.8 124.0 116.8 N 94 90.0 P
11/03/2021 11 Northeast side of proposed pool area 282.0 1 10.0 11.5 124.0 118.1 N 95 90.0 P
11/04/2021 12 East of pool area 285.0 1 10.0 6.1 124.0 111.7 N 90 90.0 P
11/04/2021 13 South side east of pool area 285.0 1 10.0 9.1 124.0 116.6 N 94 90.0 P
11/04/2021 14 Retest # 13 285.0 1 10.0 9.8 124.0 120.6 N 97 90.0 P
11/04/2021 15 Retest # 12 285.0 1 10.0 8.7 124.0 113.9 N 91 90.0 P
11/04/2021 16 Retest # 15 285.0 1 10.0 10.3 124.0 121.2 N 97 90.0 P
11/05/2021 17 Northeast side center centerline of pool area 287.0 1 10.0 12.3 124.0 119.2 N 96 90.0 P
11/05/2021 18 Pool west side slope face center of pool 282.0 1 10.0 11.3 124.0 108.5 N 87 90.0 F
11/09/2021 19 North side of pool area slope 283.0 1 10.0 9.8 124.0 118.1 N 95 90.0 P
11/09/2021 20 South side of pool area slope 286.0 1 10.0 10.9 124.0 116.6 N 94 90.0 P
11/09/2021 21 East of pool area proposed pervious paving area 290.0 1 10.0 10.8 124.0 121.1 N 97 90.0 P
11/09/2021 22 East of pool area proposed pervious paving area 290.0 1 10.0 10.7 124.0 123.2 N 99 90.0 P
11/10/2021 23 Northeast side pool area slope over build 288.0 1 10.0 10.4 124.0 123.9 N 99 90.0 P
11/10/2021 24 Southeast side pool area over build 288.0 1 10.0 10.4 124.0 119.2 N 96 90.0 P
11/10/2021 25 North side center pool area slope face 285.0 1 10.0 10.5 124.0 117.4 N 94 90.0 P
11/10/2021 26 South side center pool area slope face 285.0 1 10.0 10.2 124.0 115.6 N 93 90.0 P
11/15/2021 27 South side center of the property between grading stakes #6077 to #6074 290.0 1 10.0 10.4 124.0 123.1 N 99 95.0 P
11/15/2021 28 North side center of property between grading stakes #6076 to #6075 288.0 1 10.0 14.2 124.0 116.0 N 93 90.0 P
11/16/2021 29 North side center of property grading stake #6075 291.0 1 10.0 11.6 124.0 119.0 N 95 95.0 P
11/16/2021 30 Northeast corner#2-Car Garage 296.0 1 10.0 12.4 124.0 119.5 N 96 90.0 P
11/16/2021 31 North east side between grading stakes #6085 to #6075 289.0 1 10.0 12.4 124.0 115.5 N 93 90.0 P
11/17/21 32 2 Car Garage Area 291.0 1 10.0 11.4 124.0 123.2 N 99 95 P
12/20/2021 33 Proposed gym area 295.0 3 9.0 10.1 125.0 119.7 N 95 95.0 P
12/20/2021 34 Main level 290.0 3 9.0 10.6 125.0 120.2 N 96 95.0 P
12/20/2021 35 Main level 290.0 3 9.0 11.3 125.0 121.1 N 96 95.0 P
12/21/2021 36 Gym area 296.0 3 9.0 10.6 125.0 119.9 N 95 95.0 P
12/22/2021 37 Main house pad 292.0 3 9.0 10.7 125.0 120.9 N 96 95.0 P
Moisture
(%)
Dry Density
(pcf)
Grading
PETRA GEOSCIENCES, INC.
J.N. 20-155 Sarem Residence
1/9/2023
1 of 2
TABLE 1
Field Density Test Results
12/22/2021 38 1 car garage area 298.0 3 9.0 11.2 125.0 119.4 N 95 95.0 P
12/22/2021 39 2 car garage area 298.0 3 9.0 10.8 125.0 121.1 N 96 95.0 P
12/22/2021 40 Gym area 299.0 3 9.0 10.7 125.0 120.2 N 96 95.0 P
12/22/2021 41 Main house pad 292.0 3 9.0 10.6 125.0 119.1 N 95 95.0 P
12/22/2021 42 Main house pad 294.0 3 9.0 10.3 125.0 120.5 N 96 95.0 P
02/24/2022 43 Southwest corner of main house pad 296.0 1 10.0 9.4 124.0 119.9 N 96 95.0 P
02/24/2022 44 Southeast corner of pad south of the garage #1 297.0 1 10.0 9.4 125.0 121.6 N 97 95.0 P
02/25/2022 45 Southeast corner of pad east of garage #1 302.0 1 10.0 9.0 125.0 123.9 N 99 95.0 P
05/13/2022 46 SWC SPORTS COURT 277.0 1 10.0 11.9 124.0 119.3 N 96 95.0 P
07/15/2022 47 SOUTHEAST PAD CORNER GARAGE 297.0 1 10.0 6.9 124.0 113.9 N 91 95.0 F
07/15/2022 48 RETEST 47 297.0 1 10.0 9.8 124.0 118.4 N 95 95.0 P
01/31/2022 1 Southeast side of Bio-filtration basin 271.8 1 10.0 13.2 124.0 119.6 N 96 90.0 P
01/31/2022 2 Northeast side of basin 273.6 1 10.0 10.9 124.0 113.1 N 91 90.0 P
02/01/2022 3 South side of bio filtration 272.0 1 10.0 11.7 124.0 116.0 N 93 90.0 P
02/01/2022 4 Northeast side center of the bio filtration basin 276.0 1 10.0 10.6 124.0 107.3 N 86 90.0 F
02/01/2022 5 Retest # 4 276.0 1 10.0 9.6 124.0 113.4 N 91 90.0 P
05/13/2022 6 NWC SPORTS COURT 276.0 1 10.0 7.6 124.0 110.6 N 89 90.0 F
05/13/2022 7 RETEST # 6 276.0 1 10.0 9.0 124.0 119.3 N 96 90.0 P
05/18/2022 8 SPORTS COURT 278.0 1 10.0 8.3 124.0 115.5 N 93 90.0 P
05/18/2022 9 RETEST 8 278.0 1 10.0 11.0 124.0 118.5 N 95 90.0 P
05/20/2022 10 EAST SIDE RETAINING WALL NORTH 296.0 1 10.0 11.7 124.0 114.5 N 92 90.0 P
05/20/2022 11 EAST SIDE RETAINING WALL SOUTH 295.0 1 10.0 10.0 124.0 114.4 N 92 90.0 P
06/22/2022 12 PICKLE BALL COURT N. SIDE 278.0 1 10.0 10.9 124.0 116.6 N 94 90.0 P
06/22/2022 13 PICKLE BALL COURT N. SIDE 278.0 1 10.0 10.4 124.0 116.0 N 93 90.0 P
06/30/2022 14 WEST SIDE RETAINING WALL 283.0 1 10.0 9.7 124.0 121.6 N 98 95.0 P
07/15/2022 15 SOUTHWEST CORNER PAD FOUNDATION WALL 297.0 1 10.0 9.3 124.0 118.1 N 95 95.0 P
07/15/2022 16 SOUTHWEST SIDE PAD FOUNDATION WALL CENTER 297.0 1 10.0 9.7 124.0 115.6 N 93 95.0 F
07/15/2022 17 RETEST 16 297.0 1 10.0 9.8 124.0 119.3 N 96 95.0 P
09/07/2022 18 NORTHEASTS SIDE WALL 294.0 1 10.0 10.5 124.0 121.0 N 97 95.0 P
09/07/2022 19 NORTHEASTS SIDE WALL 295.0 1 10.0 9.4 124.0 123.2 N 99 95.0 P
09/07/2022 20 NORTHEASTS GARAGE WALL 300.0 1 10.0 11.1 124.0 119.9 N 96 95.0 P
* Test Type - N = Nuclear Gauge; DT= Drive Tube; SC = Sand Cone
Description
Reddish Brown Silty fine to coarse grained Sand with clay
Reddish Brown fine to medium grained Sand with silt
Reddish Brown fine to medium grained Sand with clay
Retaining Walls
Max. Dry
Density (pcf)
124.0
Optimum
Moisture (%)
Laboratory Maximum Dry Density
No.
1
Import 2
3
125.0
10.0
125.0
9.0
9.0
PETRA GEOSCIENCES, INC.
J.N. 20-155 Sarem Residence
1/9/2023
2 of 2
Base Map: Precise Grading Plan, 4005 Skyline Drive, Carlsbad, California; Plans by Toal Engineering, Inc., Sheet 2 dated JULY 23, 2021
500 La Terraza Blvd., Suite 150
Escondido, California 92025
PHONE: (858) 649-3707
COSTA MESA TEMECULA LOS ANGELES PALM DESERT CORONA SAN DIEGO
DENSITY TEST LOCATION MAP
4005 Skyline Drive
Carlsbad, California
DATE: January,2023
J.N.: 20-155 Figure 1
PETRA GEOSCIENCES, INC.EXPLANATION
Approximate Bottom Elevation245
Approximate Limits of this Report
Approximate Location of Field Density Test, Grading48
1
213,4
18 22
20
6 17
2
5,7
10
9 8
11 12,
15,16
13,14
19
30
22
3239
3833
36
40
35
41
31
34 43
3742
27
29
28
23
25
24
26
44
454647
48
20 Approximate Location of Field Density Test, Retaining Wall
1
2
36,7
8,9
14
10
11
12
13
4,5
15 16,17
18,19
20291
291 294
294
296
294
296
288
289
2721
273 283
291 Approximate Removal Bottom Elevation, Above Mean Sea LevelD
,,,
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~ PETRA------....i ~ GEOSCIENCES-
APPENDIX A
LABORATORY TEST PROCEDURES
LABORATORY DATA SUMMARY
~PETRA ~ GEOSCIENCES"'~ SOLID AS A ROCK
_____________________________________________________ ______________________________________
PETRA GEOSCIENCES, INC. Laboratory Address: 1251 W. Pomona Road, Unit 103, Corona, CA, 92882
J.N. 20-155
LABORATORY TEST PROCEDURES
Laboratory Maximum Dry Density Maximum dry density and optimum moisture content were determined for selected samples of soil in accordance with ASTM D 1557. Pertinent test values are given on Plate A-1.
Expansion Index
Expansion index tests were performed on selected samples of finish pad grade soil materials in accordance with ASTM D 4829. Expansion potential classifications were determined from the 2019 CBC Section
1803.5.3 on the basis of the expansion index values. Test results and expansion potentials are presented on Plates A-1.
Corrosivity Chemical analyses were performed on selected samples of finish pad grade soil to determine concentrations
of soluble sulfate and chloride, as well as pH and resistivity. These tests were performed in accordance with California Test Method Nos. 417 (sulfate), 422 (chloride) and 643 (pH and resistivity). Test results are included on Plate A-1.
MR. SCOTT SAREM August 10, 2023
4005 Skyline Drive / Carlsbad J.N. 20-155 Revision 4
_____________________________________________________ ______________________________________
PETRA GEOSCIENCES, INC. Laboratory Address: 1251 W. Pomona Road, Unit 103, Corona, CA, 92882
J.N. 20-155 PLATE A-1
Laboratory Maximum Dry Density
Sample No. Soil Type
Optimum
Moisture1
(%)
Maximum
Dry Density1
(pcf)
1 Reddish Brown, Silty fine to coarse grained Sand with clay 10.0 124.0
Import 2 Reddish Brown, fine to medium grained Sand with silt 9.0 125.0
3 Reddish Brown, fine to medium grained Sand with clay 9.0 125.0
(1) PER ASTM D 1557
Expansion Index
Sample Location Mass Grade Lot Number and
Representative Lots
Expansion1
Index
Expansion2
Potential
Pad-South South side of lot 0 Very Low
Pad-North North side of lot 0 Very Low
(1) PER ASTM D 4829 (2) PER 2019 CBC Section 1803.5.3
Corrosivity
Sample
Location
Sulfate1
(%)
Chloride2
(ppm) pH3 Resistivity3
(ohm-cm) Corrosivity Potential
Pad 0.0102 118 7.83 3,700 Concrete = Moderate Steel = Moderately Corrosive
(1) PER CALIFORNIA TEST METHOD NO. 417 (2) PER CALIFORNIA TEST METHOD NO. 422 (3) PER CALIFORNIA TEST METHOD NO. 643