HomeMy WebLinkAboutPD 2019-0023; MICHELLE LIN RESIDENCE; FINAL SOILS REPORT; 2020-02-23February 23, 2020
Mr. Frank Lin, the Owner
2732 Arland Road
Carlsbad, CA 92008
LC Engineering Corp.
GEOTECHICAL & ENVIRONMENTAL CONSULTANTS
2275 Huntington Dr., #315, San Marino, CA 91108
Tel: (626) 203-1879
Email: 1andcco98@aol.com
Project No. 156-19-I
permit# GR2019-0029
SUBJECT: FINAL GRADING OBSERVATIONS
AND FIELD DENSITY TESTS
Proposed Two-Story Residential Building and Driveway
2736 Arland Road, Carlsbad, CA 92008
Current Reference
Report/Letter(s)
Addendum
City Third Party Review Sheet
Soils Report
Gentleman:
Rep011
No.
156-19-lSA
8956.1
156-19-1 S
Date(s) of
Document
12/17/2019
12/11/2019
10/25/2019
Prepared
B
LC Engineering Corp.
Hetherington Engineering, Inc.
LC Engineering Corp.
Per your request, LC Engineering Corp. (LCEC) performed grading observations and soil density tests
for the removal and re-compaction of the sub-grade soils for the proposed two-story residential building
and driveway at the subject site. The observations and tests were performed in accordance with the
recommendations of the soils report and its addendum prepared by LCEC dated October 25, 2019 and
December 17, 2019 respectively, project specifications, the City approved plans, and the City grading
ordinances.
SITE CONDITIONS AND PURPOSE OF GRADING
The subject property is located at 2736 Arland Road, Carlsbad, CA 92008. The purpose of this grading
is to prepare a competent building pad for the proposed two-story residential building and a competent
sub-grade for the proposed driveway. The area of the proposed building was excavated to approximately
4 feet below the pre-existing ground surface. The over-excavation area was laterally extended
approximately 4 feet from outlines of the proposed building footprint. The area of the proposed
driveway was over-excavated to approximately 2 feet below the pre-existing ground surface. The total
depth of compacted fill was approximately 5 feet at the building pad area; and the total depth of
compacted fill was approximately 2 feet at the proposed driveway. The bottoms of the over-excavation
were checked and approved by a representative of LCEC. Compaction tests were conducted in no more
than 2-foot vertical interval. The grading limits and compaction test locations for .the proposed two-story
building and driveway are shown on Figure 1.
GRADING PROCEDURES
In general, the grading was performed as follows:
02/23/2020 Project No. 156-19-1
a) Fill soils, unsuitable soils, and other deleterious materials were first stripped of at the areas of the
proposed two-story building and driveway.
b) The bottoms to receive fill in the proposed two-story building pad and driveway were excavated to
dense native soils and approved by a representative of LCEC. The soils exposed on the bottoms
consisted of reddish brown silty sand in dense condition and approved prior to placing fill.
c) Bobcat excavator, Cat loader, roller, and water hose were used for excavation and compaction.
Onsite soils and import soils were used as compacted fill. The onsite soils consisted of reddish
brown silty sand. The building pad was backfilled with the onsite soils. Import soils were used to
backfill the proposed driveway. The import soils consisted of brown silty sand, which was suitable
for backfilling the driveway area and approved by a representative of LCEC. All fill soils were
spread in 6 to 8 inch lift, moistened to near the optimum moisture content, placed in layers not
exceeding eight inches, compacted, and tested in intervals no more than two feet to the finished sub-
grade.
SPECIFICATION AND TEST RESULTS
The maximum dry densities for the onsite and import soils were tested in accordance with the current
standard of ASTM D 1557 method. The test results were tabulated in Table 1. The specified minimum
degree of compaction is 90 percent of the maximum dry density. Field density tests were performed in
accordance with the curre.µt ASTM Standard D1556 (Sand Cone)/D 6938 (nuclear gauge, formerly
named D2922). The test results are tabulated in Table 2. The test locations are shown on Figure 1.
As indicated in Table 2, "NG" represents the Nuclear Gauge test. "SC" represents the Sand Cone Test.
Wherever field density test results failed, the soils were scarified, re-mixed to near optimum moisture
and re-compacted to achieve the required density.
CONCLUSIONS AND RECOMMENDATIONS
The compacted fills reported herein have been properly placed and compacted as primary structural fill
for the proposed two-story building and as secondary fill for the proposed driveway. The work inspected
and approved by a representative of LCEC was performed in accordance with the soils report, the
applicable provisions of the City Building Code and grading ordinances, and the current California
Building Code.
The grading observations and tests and recommendations for the design and construction of the project
are summarized in the following:
2
• The observations and test results indicated that the removal and re-compaction of the sub-grade
soils were accomplished in accordance with project specifications, recommendations of LCEC,
and the City grading ordinances.
• Conventional continuous/pad footings can be designed to support the proposed two-story building.
Continuous footings can be designed for an allowable bearing pressure of 2,000 pounds per square
foot (psf) for a minimum of 18 inches in width and embedded a minimum of 18 inches into
compacted fill below the lowest adjacent grade. Pad footings can be designed for an allowable
LC Engineering Corp
2275 HUNTINGTON DRIVE, #315 SAN MARINO, CA 91108 TEL: 626-203-1879
02/23/.2020 Project No . 156-19-1
pressure of 2,000 psf and a minimum of 24 inches in width and embedded a minimum of 24 inches
into compacted fill. The bearing capacity may be increased by one third when considering short
duration wind or seismic loads.
• A friction coefficient of 0.3 and a lateral bearing of 300 pounds per cubic foot (pcf), to a
maximum of 3,000 pcf, can be used to resist lateral loads. When combining passive earth
pressure and frictional resistance, the passive earth pressure should be reduced by one third.
• All continuous footings should be reinforced with a minimum of two #4 rebars near the top and
two # 4 rebars near the bottom.
• Foundations designed and installed in accordance with the recommendations outlined in this
report are anticipated to undergo a total settlement of less than one inch. Differential settlement
over a horizontal dista11ce of10 feet will be lessfhan 1/2 inch.
• The sub-grade for the proposed driveway was completed, but aggregate base has not been placed
yet. All aggregate bases should be placed and compacted to a minimum 90 percent of the
maximum density in accordance with the current standard of ASTM D1557 method.
• Final grading should provide a positive drainage to divert surface water away from the
foundation areas in compliance with the local jurisdiction's grading requirements. All pad
drainage should be collected and diverted away from the proposed buildings in non-erosive
devices. Roof gutter should be provided to collect runoff water and divert to down spouts leading
down to the ground surface and discharge off-site. Planters adjacent to buildings or slope should
be designed with concrete bottom and sub-drains leading away from the building or slope area.
All underground plumbing fixtures should be absolutely leaked free. Proper drainage should also
be provided to divert surface water away from the building pad area during construction. This is
especially important when construction takes place during the rainy season.
It is our opinion that the proposed construction will be safe against any geotechnical hazards from
landslides, settlement, or slippage and the proposed work will not adversely affect the subject and
adjacent properties in compliance with the City Code.
This report pertains only to the grading as described herein and is subject to be reviewed by the
controlling authority for the project.
Respectfully submitted,
LC Engineering Corp.
Jack Liu
Project Geologist
Shaofu Chen, P.E. C76834
Principal Engineer
./
Distribution: ( 4) Addressee
3 LC Engineering Corp
2275 HUNTINGTON DRIVE, #315 SAN MARINO, CA 91108 TEL: 626-203-1879
02/23 /2 020 Project No. 156-19-1
4
TABLE 1
LABORATORY TEST SUMMARY
OPTIMUM MAXIMUM DRY SOIL CLASSIFICATION DENSITY (lb./cu.ft) MOISTURE SOIL TYPE
CONTENT(%)
Onsite reddish brown silty sand 13 3.4 7.7 A
TEST
NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Import brown silty sand 130.9 9.8 B
DATE
2020
02/13
02/13
02/13
02/13
02/19
02/19
02/19
02/19
02/19
02/19
02/22
02/22
02/22
02/22
TABLE2
FIELD DENSITY TEST SUMMARY
ELEVATION TEST LOCATION & MOISTURE DRY RELATIVE SOIL
BELOW PRE-TEST METHODS (SC: CONTENT DENSITY COMPACTION TYPE
EXISTING SAND CONE, NG: (%) (lb./cu.ft) (%)
GRADE (ft) NEUCLEAR GAUGE)
-3 .0 Building pad, NG 8.5 120.5 90 A
-3.0 ",NG 8.9 121.5 91 A
-2.0 ",NG 9.3 122.0 91 A
-2.0 ",NG 9.5 122.3 92 A
-1.0 ",NG 7.9 120.3 90 A
-1.0 ",NG 8.5 121.5 91 A
0 ",SC 9.1 121.3 91 A
0 ",NG 9.2 122.5 92 A
+1.0 ",NG 9.0 123.1 92 A
+1.0 ",NG 8.9 122.0 91 A
-1.0 driveway, NG 10.5 124.0 95 B
-1.0 ", SC 10.1 124.5 95 B
0 ",NG 11.0 125.0 95 B
0 ",NG 9.9 124.8 95 B
LC Engineering Corp
2275 HUNTINGTON DRIVE, #315 SAN MARINO, CA 91108 TEL: 626-203-1879
02/23/2020 Project No. 156-19-1
5
CITY OF CARLSBAD
ENGINEERING DEPARTMENT
ENGINEERING'S CERTIFICATE OF COMPLIANCE FOR COMPACTED EARTH FILLS
Parcel No.: 156-142-56
PROJECT NO: 156-19-I
JOB ADDRESS: 2736 Arland Road, Carlsbad, CA 92008
SOIL TESTING AGENCY: LC Engineering Corp.
PROPERTY OWNER'S NAME: Mr. Frank Lin
OWNER'S ADDRESS: 2732 Arland Road, Carlsbad, CA 92008
DATE WORK STARTED ON PROJECT: 2/11/2020
DATE FILL WAS COMPLETED: 02/22/2020
DATE OF THIS CERTIFICATE: 02/23/2020
TO THE SUPERINTENDENT OF BUILDING:
Permit# GR2019-0029
I hereby certify that I have personally inspected and tested the placing of compacted earth fill on the above
described property, and on the basis of these inspections and tests it is my opinion that the same was placed
in conformity with the requirement of the City of Carlsbad Building Code.
Shaofu Chen
Principal Engineer
California License No. P.E. C76834
For the purpose of this Certificate, to "have personally inspected and tested" shall include inspection and
testing performed by any person responsible to the licensed engineer signing this certificate. Where the
inspection and testing of all or the work above is delegated, full responsibility shall be assumed by the
licensed engineer whose signature is affixed thereon.
LC Engineering Corp
2275 HUNTINGTON DRIVE, #315 SAN MARINO, CA 91108 TEL: 626-203-1879
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FIGURE 1 SITE PLAN WITH TEST LOCATIONS
2736 Arland Road, Carlsbad, CA 92008
LC Engineering Corp Project No. 156-19-1