HomeMy WebLinkAboutCDP 05-46; MOSS RESIDENCE; FINAL SOILS REPORT; 2020-08-07
07 August 2020
Mr. Steven Moss Job No. 07-9342
25408 Colette Way
Calabasas, CA 91303
Subject: Report of Final Grading Observations and Soil Testing
Moss Residence
5015 Tierra del Oro
Carlsbad, California
Dear Mr. Moss:
As requested and required by the City of Carlsbad, Geotechnical Exploration, Inc.
hereby presents this report of final observation and soil testing for the grading
performed at the subject site. The field work reported herein was performed between
May 15 and November 17, 2018. We previously performed a geotechnical
investigation of this site, the results of which were presented in our “Report of
Preliminary Geotechnical Investigation and Geologic Reconnaissance” dated April 20,
2007, as well as the following documents:
1. Addendum to Report of Geotechnical Investigation, dated July 2, 2007;
2. Response to Carlsbad Engineering Department, dated October 4, 2007;
3. Addendum to Report of Geotechnical Investigation and Response to Carlsbad
Engineering Department, dated October 9, 2007;
4. Addendum to Report of Geotechnical Investigation, dated April 22, 2008;
5. Revised Addendum to Report of Geotechnical Investigation, dated July 9,
2008;
Moss Residence Job No. 07-9342 Carlsbad, California Page 2
6. Old Revetment vs. New Revetment, dated July 9, 2008;
7. Update to Report of Geotechnical Investigation, dated July 14, 2010;
8. Update to Report of Geotechnical Investigation, dated July 11, 2011;
9. Update to Report of Geotechnical Investigation, dated July 16, 2012;
10. Update to Report of Geotechnical Investigation, dated July 17, 2013;
11. Update to Report of Geotechnical Investigation, dated July 7, 2014;
12. Update to Report of Geotechnical Investigation, dated June 29, 2015;
13. Updated Site Observations of Bluff Conditions, dated January 5, 2016
14. Response to California Coastal Commission Staff Report, dated January 12,
2016
15. Response to California Coastal Commission Staff Report, dated February 4,
2016
16. Response to California Coastal Commission Staff Comments, dated April 6,
2016;
17. Report of Limited Geotechnical Investigation Proposed Storm Water Infiltration
BMPs, dated October 24, 2017;
18. Update to Report of Geotechnical Investigation, dated February 8, 2018;
19. Plan Review, dated March 6, 2018;
20. Grading Plan Review, dated March 6, 2018;
21. Basement Temporary Cuts, dated March 12, 2018;
22. Revised Temporary Basement Cuts, dated March 22, 2018
23. Response to City of Carlsbad City Engineer Comments, dated April 2, 2018;
24. Completion of Basement Level Pad Rough Grading, dated June 6, 2018;
25. Updated Site Observations of Bluff Conditions, dated March 5, 2019
26. Completion of Basement Wall Backfill, Upper Level Building Pad and Garage
Building Pad Grading, dated November 8, 2018
Moss Residence Job No. 07-9342 Carlsbad, California Page 3
SITE DESCRIPTION
The property is known as: Assessor’s Parcel No. 210-020-15-00, Lot 15, according
to Recorded Map No. 3052, in the City of Carlsbad, County of San Diego, State of
California.
The existing, rectangular shaped lot consists of approximately 13,650 square feet,
and is located at 5015 Tierra del Oro Street (see Figure No. I). The property is
bordered on the north by a vacant lot and south by existing residential properties at
a slightly higher elevation; on the east by the northern terminus of the north-south
trending Tierra Del Oro Street; and on the west by rip-rap protected slope, a sandy
beach and the Pacific Ocean. Refer to Figure No. II.
Prior to our involvement, the structure on the site consisted of single-story, single-
family residence founded on a raised wood floor with a perimeter concrete foundation,
an attached garage, a concrete driveway, concrete and brick walkways, and wood
decks and walkways. Vegetation on the site consisted primarily of trees, decorative
shrubbery, and grass with iceplant on the westerly slope.
The new construction primarily consists of a new single-family residence including
two-stories in height over a basement-level living area that opens to the beach on
the west side; an attached garage on the east side, a driveway, and associated
improvements. The residence was constructed of standard-type building materials
utilizing conventional foundations with a concrete slab on-grade floor.
Moss Residence Job No. 07-9342 Carlsbad, California Page 4
SOIL TESTING
Representative soil samples were collected during the grading to determine
laboratory maximum dry density of the soils per ASTM D1557-12e1. Field density
tests were performed at approximate locations shown on Figure No. II, Plot Plan, in
accordance with ASTM D6938-17a. The complete list of field density tests results is
shown on Table A of Figure No. IIIa, and laboratory soil compaction test results are
shown on Table B of Figure No. IIIb.
FIELD OBSERVATIONS
1. Our representative observed the basement level pad grading between May 15
and June 6, 2018. Temporary cuts were monitored and were considered safe
during the basement level pad grading. Approximately 1 foot of the disturbed
surface basement pad soils were remoisturized and recompacted. A report
was prepared with our results and issued on June 6, 2018.
2. The basement retaining wall backfill was observed and tested between August
14 and 31, 2018. Prior to backfill placement, it was observed that the
waterproofing, geo-composite drainage boards, and a subdrain behind the
east, north, and south basement retaining walls had been placed.
3. The east side garage pad grade soils were observed and tested intermittently
between September 4 and November 7, 2018. Approximately 4 to 6½ feet of
the upper garage pad grade soils were remoisturized and recompacted,
including the area where an abandoned septic tank was encountered and
removed in the northeast area of the garage.
Moss Residence Job No. 07-9342 Carlsbad, California Page 5
4. Footing trench excavations were observed intermittently between July 9 and
September 17, 2018. The observed footing excavations include the 6
basement level columns; the perimeter basement level footing excavations
(which include the east, north, and south retaining walls); the southeast stair
retaining wall; and all upper level/main level garage footing excavations.
The observed footings were founded in dense formational soils or properly
recompacted soils. A footing memo was issued to the contractor or
contractor’s representative for the observed and approved footing excavations.
5. Backfill placement for utilities or exterior hardscape subgrade soils was not
observed or soil tested.
Grading equipment used for compaction consisted of an excavator, a Bobcat, and a
mini-excavator with loader bucket. Water was added, when needed, to increase the
soil moisture. Field density tests yielded a relative compaction of at least 90 percent
of maximum dry density at the tested locations. Density tests were performed with
a nuclear gauge testing apparatus in accordance with ASTM D6938-17a. The
maximum dry density of the soils was determined per ASTM D1557-12e1. On-site
soils were used during the observed grading and field density testing. In general,
the on-site soils consisted of light grey-brown and light red-brown sand and red-
brown silty sand. The on-site soils were visually classified to have low expansive
potential (E.I.≤ 50).
Proper finish surface drainage for the site should be implemented by the general
contractor prior to completing construction. Field density tests and approximate
limits of the graded areas are shown in the attached Plot Plan, Figure No. II.
Moss Residence Job No. 07-9342 Carlsbad, California Page 6
Any future grading and earthwork should be observed by our field representative
prior to form and steel reinforcing placement, and just prior to concrete placement.
Any future utility or drainage trench backfill, or retaining wall backfill should also be
performed under the observation and testing of our firm. Any subgrade testing for
pending exterior flatwork should be observed and tested by our firm. A report will
be provided issued after additional soil-related work is performed under our
observation and testing.
SITE SUITABILITY AND COMPLIANCE
The observed and tested areas of the project site are, in our professional opinion,
suitable for their intended use. The dense formational soils are, in our professional
opinion, suitable to support the recompacted fill, structure foundations, and new
exterior improvements.
We certify that the soil engineering and engineering geologic aspects of the observed
grading operation are in compliance with our geotechnical report dated April 20,
2007, and the approved civil grading plans prepared by Coffey Engineering, Inc.
LIMITATIONS
The findings and opinions presented herein have been made in accordance with
currently accepted principles and practice in the field of geotechnical engineering in
the City of Carlsbad. No warranty, either expressed or implied, is made.
All statements in this grading report are applicable only for the grading operation
observed by our firm. If any loose fill soils were placed without our knowledge or
observation, the firm Geotechnical Exploration, Inc. shall not be held responsible
Moss Residence Job No. 07-9342 Carlsbad, California Page 7
for the fill soils placed without our observations and testing at any other time, or
subsequent changes to the site by others, which directly or indirectly cause poor
surface or subsurface drainage, water erosion, and/or alteration of the strength of
the compacted fill soils.
It is not within the scope of our services to provide quality control oversight for
surface or subsurface drainage construction or retaining wall sealing and base of wall
drain construction. It is the responsibility of the contractor to verify proper wall
sealing, geofabric installation, protection board installation (if needed), drain depth
below interior floor or yard surfaces; pipe percent slope to the outlet, etc.
In the event that any changes in the nature, design, or location of the building or
improvements are planned, the conclusions and recommendations contained in this
report should not be considered valid unless the changes are reviewed and the
conclusions of this report modified or verified in writing.
This opportunity to be of service is sincerely appreciated. If you have any questions
regarding this letter, please contact our office. Reference to our Job No. 07-9342
will help expedite a response to your inquiry.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
_______________________________ ______________________________ Jaime A. Cerros, P.E. Richard A. Cerros, E.I.T.
R.C.E. 34422/G.E. 2007 Staff Engineer
Senior Geotechnical Engineer
VICINITY MAP
Moss Residence
5015 Tierra Del Oro
Carlsbad, CA.
Figure No. I
Job No. 07-9342
Site
Thomas Bros. Guide San Diego County, pg 1126-F2
Approximate Location ofField Density Test5741211625981025212320241317141518191632122Approximate Limits of Remedial GradingMoss Residence5015 Tierra Del OroCarlsbad, CA.Figure No. IIJob No. 07-9342PLOT PLANREFERENCE: This Plot Plan was prepared from an EXISTINGundated GRADING PLAN by COFFEY ENGINEERINGINC. and from on-site field reconnaissance performed by GEI.Scale: 1” = 20’(approximate)LEGENDNOTE: This Plot Plan is not to be used for legalpurposes. Locations and dimensions are approximate.Actual property dimensions and locations of utilitiesmay be obtained from the Approved Building Plansor the “As-Built” Grading Plans.( July 2020 )07-9342-p3.aiGEOLOGIC LEGENDArtificial FillOld Paralic Deposits( units 6-7 )Qaf6-7QopSantiago FormationTsaQaf6-7QopTsaQaf6-7QopTsaQaf6-7QopTsaQaf6-7Qop
TABLE A ApproximateWater DryDegree of Test Elevation Content DensityCompaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No. Remarks 1 5/30/18 Basement Pad FSG (34) 7.2 118.7 97 22 5/30/18 Basement Pad FSG (34) 5.1 114.093 23 8/15/18 Basement Wall Backfill FSG -6' 11.7 129.298 34 8/15/18 Basement Wall Backfill FSG -6' 8.8 122.193 35 8/15/18 Basement Wall Backfill FSG -6.5' 8.2 120.091 36 8/16/18 Basement Wall Backfill FSG -4' 7.3 121.692 37 8/16/18 Basement Wall Backfill FSG -4'7.1 122.393 38 8/16/18 Basement Wall Backfill FSG -6'8.0 124.69539 8/21/18 Basement Wall Backfill FSG -3'6.0 119.791 3108/22/18Basement Wall Backfill FSG -4'8.9 116.590411 8/22/18 Basement Wall Backfill FGS -2'7.7 117.090 4128/23/18Basement Wall Backfill FSG6.6 122.294413 8/27/18 Basement Wall BackfillFSG -4' 6.4 126.596 3148/27/18Basement Wall BackfillFSG -3' 5.9 128.097315 8/26/18 Basement Wall BackfillFSG -2' 5.7 129.298 3168/29/18Basement Wall BackfillFSG -0.5' 6.9 125.6953178/29/18Basement Wall BackfillFSG -4' 7.1 129.098 3188/31/18Basement Wall BackfillFSG -2' 8.8 126.2963199/4/18Garage Pad FSG -6.5' 8.0 124.0943209/4/18Garage Pad FSG -4.5' 7.4 125.2953219/5/18Garage Pad FSG -3.5' 7.0 122.1933229/5/18Garage Pad FSG -3' 7.7 123.2933239/7/18Garage Pad FSG -2' 10.5 118.2903249/11/18Basement Wall BackfillFSG 12.0 121.79232511/7/18Garage Pad FSG 6.9 123.8943 Job No. 07-9342 Figure No. IIIaSUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938)Notes: 1) Curve number refers to Table B 2) FSG denotes finish subgrade elevation 3) FBG denotes finish base grade elevation 4) FPG denotes finish pavement grade
Job No. 07-9342 Figure No. IIIb TABLE B LABORATORY COMPACTION TEST RESULTS (ASTM D1557) Compaction Maximum Optimum Test Source of Dry Density Water Content Curve No. Description of Material Material (pcf) % C-1 (SP) SAND; Light Grey-Brown On-site 110.0 13.8 C-2 (SP) SAND; Light Red-Brown On-site 122.0 13.0 C-3 (SM) SILTY SAND; Red-Brown On-site 131.8 8.0 C-4 (SM) SILTY SAND; Red-Brown On-site 130.0 8.8