HomeMy WebLinkAbout2221 1%2 S Cypress Ave - Soils ReportTMC ENGINEERS INC.
Geotechnical, Structural and Civil Engineering
RECE,VEi-J
MAY 21 2020
City of SantaAna
Aptil 20,2020
Mr. MINH TRUNG V. TRAN
2221 1t2 CYPRESS AVE,
SANTA ANA, CA92707
ln accordance with your request, I am pleased to submit this geotechnical engineering report for the
proposed development at subject site. The purpose of this report was to evaluate the subsurface
conditions and provide recommendations for foundation designs and other relevant parameters for the
proposed construction.
Based on the findings of our field exploralion, laboratory testing and engineering analysis, the proposed
construction of the subject site for the intended use rs feasible from the geotechnical engineering
viewpoint, provided that specific recommendations set forth herein are followed.
This opportunity to be of service is sincerely appreciated. lf you have any questions pertaining to this
report, please call the undersigned.
Respectfully submitted,
Tien Chu
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Subject: Report of Geotechnical Engineering lnvestigation, Proposed Residential
Development a|2221 112 CYPRESS AVE, SANTAANA, CA92707. ProjectNumber:14120DT
Gentlemen:
REPORT OF GEOTECHNICAL ENGINEERING
INVESTIGATION
Proposed Residential Development at
2221 1 /2 CYPRESS AVE, SANTA ANA, CA 927 07
Prepared by TMC ENGINEERS INC.
Project No.: 14120DT
/
Page 2
l.O INTRODUCTION
1.1 Purpose
This report presents a summary of our preliminary geotechnical engineering investigation for
the proposed development at the subject site. The purposes of this investigation were to
evaluate the subsurface conditions at the area of proposed construction and to provide
recommendations pertinent to grading, foundation design and other relevant parameters.
1.2 Scope of Services
Our scope of services included:. Review of available soil and geologic data of the area.
. Logging and sampling of hand auger boring to a maximum depth of 5 feet below the
existing ground surface. Boring logs are presented in Appendix "A" (Field lnvestigation).. Laboratory testing of representative samples collected from the proposed construction
area to establish engineering characteristics of the on-site soils. The laboratory test results are
presented in Appendix B (Laboratory Testing) and on the boring logs (Appendix A).
. Engineering analyses of the geotechnical data obtained from our background studies,
field investigation, and laboratory testing.
. Preparation of this report presenting our findings, conclusions, and recommendations
for the proposed development.
1.3 Proposed Construction
It is anticipated that the proposed construction is a residential buildings with a One-story house
is proposed to add 2nd house at back of existing lot site. The structure of the proposed
residential building is anticipated to be one to tvvo-story in height. Column loads are be light to
medium. Final grade is anticipated to be near the existing grade.
1.4 Site Conditions
The subject site is located at East side of Cypress street, North of Warner Ave, East of Main
street, West of Main street., South of Edinger Ave within a fully development area.
An existing one story house with typical concrete driveway, sidewalks, rear yard.
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The subject site is relatively flat and is currently occupied by a residential house and a garage.
No major surface erosions were observed at the time of our field investigation.
2,0 SUBSURFACE EXPLORATION AND LABORATORY TESTING
2.1 Subsurface Exploration
Our subsurface exploration consisted of drilling hand auger boring to a maximum depth of 5
feet below the existing ground surface. Relatively undisturbed, bulk samples were collected
during drilling for laboratory testing. The approximate locations of the boring are shown on the
attached Site Plan. Boring logs are presented in Appendix A.
2.2 Laboratory Testing
Representative samples were tested for the following parameters: Atterberg Limits, expansion
index. The results of our laboratory testing along with a summary of the testing procedures are
presented in Appendix B.
3.0 SUMMARY OF GEOTECHNICAL CONDITIONS
3.1 Soil Conditions
Based on field observation and testing of sampler of the near ground surface soil. The ground
surface soils consist of silty very fine sand. ln general, these soils exist slightly moist to moist
condition.
3.2 Groundwater
Ground water was not encountered at a depth of about 5 feet below the existing ground surface
during our subsurface investigation.
Based on our review of lhe "Historically Highest Ground Water Contours and Borehole Log
Data Locations, Anaheim and Newport Beach Quadrangle", it is estimated that the highest
ground water level is approximate 5 feet below the existing grade. lt should be noted that the
CDMG ground water map is obtained by evaluating technical publications, geotechnical
borehole data, water-well logs dating back to the "turn-otthe-century". This report also
indicated that ground water levels in the areas from 1 960-1997 data ate generally 5 to 50 feet
deeper than the earlier measured data. No specific date was provided pertaining to the high
ground water level.
Deep footings and excavations are not proposed for this site, therefore the effect due to ground
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water are not anticipated for the proposed structural.
Latitude = 33.7171005,
Longitude = -117.8662843
Site Class: D
Ss= 1.279
S1= 0.558
SMs= 1.279
SDs=0.853
Seismic Design Category: D
This minimum code values are intended to protect life and may not provide an acceptable level
of protection against significant cosmetic damage and serious economic loss. A significantly
higher than code lateral design parameter would be necessary to further reduce potential
economic loss during a major seismic event. Structural engineers, however, often regard
higher than code values as impractical for use in structural design. The structural engineer and
project owner must decide what level of risk is acceptable and to assign appropriate seismic
values for use in structural design. The risk of damage to the structural due to a large
earthquake cannot be totally eliminated and obtain appropriate insurance as a mitigation
measure is strongly recommended.
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SEISMIC DESIGN CONSIDERATIONS
Although no know active faults traverse through the subject site, like most of Southern
California, the subject site lies within a seismically active area. Earthquake resistance
structural design is recommended. Designing structural to be earthq uake-proof is generally
considered to be impractical, especially for private projects, due to cost limitations, significant
damage to structures may be unavoidable during large earthquakes. The structural design of
the proposed structures should be based on the 2019 California Building Code. The following
minimum seismic parameter should be used:
5.0 SEISMIC HAZARDS
5.1 Liquefaction Potential
Liquefaction is the transformation of a granular material from a solid to a liquid state as a result
of as flow land sliding, lateral spread, loss of bearing capacity, or settlement.
Based on the Seismic Hazard Zones Map, Anaheim and Newport Beach Quadrangle, the site
is not located within a potential liquefaction zone. Therefore, liquefaction may not occur at the
site.
The city of Santa Ana has allowed many new one to two-story houses supported by regular
footings with slab on grade to be constructed in residential areas where the surface and
subsurface are similar to the subjected site.
5.2 Lurching
Soil lurching refers to the rolling motion on the surface due to the passage of seismic surface
waves. Effects of this nature are not considered significant on the subject site where the
thickness of alluvium does not vary appreciably under structures.
5.3 Surface Rupture
Surface rupture is a break in the ground surface during or as a consequence of seismic activity.
The potential for surface rupture on the subject site is considered negligible due to the absence
of known active faults at the site.
5.4 Ground Shaking
Throughout southern California, ground shaking, as a result of earthquakes, is a constant
potential hazard. The relative potential for damage from this hazard is a function of the type
and magnitude of earthquake events and the distance of the subject site from the event.
Accordingly, proposed structures should be designed and constructed in accordance with
applicable portions of the building code.
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6.0 coNcLUstoNS
Based on the results of our subsurface investigation, it is our opinion that the proposed
residential development is feasible from a geotechnical standpoint, provided the
recommendations contained herein are incorporated in the design and construction. The
following is a summary of the geotechnical design and construction factors that may affect
development of the site.
6.1 Seismicity
Based on our studies on seismicity, there are no known active faults crossing the property.
However, the site is located in a seismically active region and is subject to seismically induced
ground shaking from nearby and distant faults, which is a characteristic of all Southern
California areas.
6.2 Liquefaction
We recommend the proposed new structure be designed based on upto-date building codes
and be supported by a strengthened foundation system as recommended in this report to
reduce the potential adverse effects due to the potential liquefaction to the proposed new
structure.
6.3 Groundwater
Ground water was not encountered at a depth of about 5 feet below the existing ground
surface during our subsurface investigation. ln our opinion, groundwaler will not be a
problem during the near surface construction.
6.4 Expansion Potential
Based on our field observation and testing of sample of the near ground surface on-site earth
materials, the foundation subgrade soils at the site generally consisted of silty very fine sand
and have a very low expansion potential.
Page 7
7.0 RECOMMENDATIONS
The following recommendations should be incorporated into the design or construction
phases.
7.1 Grading
7.1.1 Site Preparation
Prior to initiating grading operations, any existing vegetation, trash, debris, over-sized
materials (greater than '12 inches), and other deleterious materials within fill areas should be
removed from the site.
7.1.2 Surficial Soil Removals
For the proposed new room extension areas, after removal of existlng concrete slabs and/or
vegetation including roots. lt is recommended that the top 3 feet thick near surface earth
materials should be over-excavated and re-compacted. Removal should be extended at least
3 feet beyond building lines.
No deeper removal is anticipated, however, if deeper loose soils are encountered, deeper
removal and re-compaction will be required. This will be determined at the field by the project
geotechnical/civil engineer, based on the actual conditions exposed at the time of site grading.
The removed clean on-site earth materials without any debris, vegetation and roots can be re-
used as fill or back fill material.
Fill, back fill material or additional imported soils should be free of organic matter and oversize
material, 6 inches or greater in diameter, placed in near-horizontal loose lift not to exceed 4
inches in thickness and moisture conditioned to slightly over optimum moisture content prior
to compaction.
lmported soil, if any, should have a very low expansion potential and should be geotechnical
observed/tested and accepted by the geotechnical/civil engineer prior to using at the site.
ln general, grading at the site should be performed in accordance with the requirements of the
city of Huntington Beach and under the geotechnical observation and testing of the project
geotechnical / civil engineer. The compaction criteria for fill and backfill material is a minimum
of 90% of the maximum density determined in accordance with ASTM Test Method D1557.
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7.1 .3 Structural Backfill
The onsite soils may be used as compacted fill provided they are free of organic materials
and debris. Fills should be placed in relatively thin lifts; brought to near optimum moisture
content, then compacted to obtain at least 90 percent relative compaction based on
laboratory standard ASTM D-1 557-07.
7.1.4 Site Drainage
Foundation and slab performance depend greatly on how well runoff waters drain from the
site. This is true both during construction and over the entire life of the structure. The ground
surface around structures should be graded so that water flows rapidly away from structure.
Roof gutters and downspouts should be properly provided and maintained.
ln the future, sources of uncontrolled water, such as leaky sewer, water (domestic, irrigation)
or drain pipes should be repaired if identified.
The requirements of the governmental agency and the current CBC should be followed, as
needed.
Page 9
7.2 Shallow Foundation Design
7.2.1 Allowable foundation and Lateral Pressure:
Based on our field investigation and laboratory testrng results. ln accordance with Section
1806.2 of the 2019 California Building Code. lt is recommended that the following
parameters should be considered in the foundation design and construction:
For conservative, the lowest values in table 1806.2, 20'19 CBC Code, allowable bearing
value of 1500 pounds per square foot.
7.2.2 Settlement
Distress to the existing house due to settlement of the underlying soil was not observed.
Settlement of soils underlying is not a concerned for the proposed development.
Under construction, differential settlement between adjacent columns is not anticipated to
exceed 1/4 inch for the adjacent column spaced at a distance of about 40 feet.
7.2.3 Laleral Pressu res
Passive earth pressure may be computed as an equivalent fluid pressure of 150 pounds per
cubic foot, with a maximum earth pressure of 1500 pounds per square foot. An allowable
coefficient of friction between soil and concrete of 0.3 may be used with the dead load forces.
When combining passive pressure and frictional resistance, the passive pressure component
should be reduced by onethird.
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7.2.4 Foundation Construction
It is anticipated that the entire structure will be underlain by onsite soils of very low expansion
potential. All new footings should be founded at a minimum depth of 24 inches below the
lowest adjacent ground surface. All continuous footings should have at least two No. 4
reinforcing bars placed both at the top and two No. 4 reinforcing bars placed at the bottom of
the footings.
+ New building footings:
New continuous footings 12 inches wide at one-story, 15 inches wide at two-story. 24 inches
deep at interior and exterior footings. Shallow pad footings at least 24 square inch and 24
inches deep. All continuous new footings should have at least two No. 4 reinforcing bars
placed at the top and two No. 4 reinforcing bars placed at the bottom of the footings.
7.2.5 Concrete Slab
Concrete slabs should be a minimum of 4 inches thick and reinforced with a minimum of No.
4 bars spacing at 16 inch both ways and its equivalent. All slab reinforcement should be
supported to ensure proper positioning during placement of concrete.
Concrete slabs in moisture sensitive areas should be underlain with a vapor barrier
consist of a minimum of 10-mil vaper retarder with all laps sealed. A minimum of 2 inch of
sand should be placed over the membrane to aid in uniform curing of concrete and 2 inch of
sand under vapor barrier.
Alternate per Cal Green code, a 4-inchthick base of /z inch or larger clean aggregate
shall be provided with a 10-mil vaper retarder with all laps sealed in direct contact with
concrete.
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7.3 Temporary Trench Excavation and Backfill
All trench excavations should conform to CAL-OSHA and local safety codes. All utilities
trench backfill should be brought to near optimum moisture content and then compacted to
obtain a minimum relative compaction of 90 percent of ASTM D-1557-07.
7.4 Nonstructural concrete Flatwork: Sidewalk and Private Driveway
4 inches (sidewalk) and 5 inch (driveway) minimum thickness reinforce concrete with # 3 at
24" on center. Crack control with saw cut or deep tool joint to a minimum of 1/3 the concrete
thickness, maximum joint spacing is 5 feet (sidewalk) and 10 feet or quarter cut (driveway)
whichever closer.
8.0 CORROSION POTENTIAL
Sulfate attack was not observed for the existing buildings in this subjected area. Type ll
cement with concrete strength 2500 psi is recommended to use, Water-Cement ratio=0.S.
Other requirement from government agencies, if any, can be followed.
It is recommended that the subsurface soils can be corrosive to buried metal pipe. lt is
recommended that any underground steel utilities be blasted and given protective coating.
Should additional protective measures be warranted, a corrosion specialist should be
consulted.
9.O INSPECTION
As a necessary requisite to the use of this report, the following inspection is recommended:
Temporary excavations.
Removal of surficial soils.
Backfill placement and compaction.
. Foundation excavations. The geotechnical engineer should be notified at least 1 day in
Page 12
advance of the start of construction. A joint meeting between the client, the contractor, and
the geotechnical engineer is recommended prior to the start of construction to discuss
specifi c procedures and scheduling.
+ rhe materia,s "",",,,",j00;:il1::'l::,:.|o}j'#[]o':"f ,aboratory testins prosram
are believed to be representative of the area. However, soil may vary in characters between
the exploratory borings. Since our investigation is based on the site materials observed,
selected laboratory testing, and engineering analyses, the conclusions and
recommendations are professional opinion. These opinions have been derived in accordance
with current standard of practice.
+ Based on our site investigation and recommendation, we believed that the proposed
improvements will not adversely impact adjoining site.
Page 13
11.0 REFERENCES
lshihara, K. and Yoshimine, M., (1992), "Evaluation of Settlements in Sand Deposits Following
Liquefaction During Earthquakes", Japanese Society of Soil Mechanics and Foundation Engineering,
Vol.32, No. 1, pp. 173-188
Guidelines for Evaluating and Mitigating Seismic Hazards in California, 2008 Special Publication 1174,
revised and re-adopted Seplember 1 1 , 2008.
T.Y. Loud, l.M. ldriss, and et. al. (2001), "Liquefaction Resistance of Soils: Summary Report from the
1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils",
Journal of the Geotechnical Engineering Division, American Society of Civil Engineers, Vol. 127, No.
GT10, pp.817-833.
California Geological Survey "Probabjlistic Seismic Hazard Mapping Ground Motion Page."
California Division of Mines and Geology, 1998, Seismic Hazatd Zone Report for the Newport Beach
Seismic Hazard Zone.
EERC, "Recent Advances in Soil Liquefaction Engineering: A Unified and Consistent Framework",
EERC Report No.2003-06,26th Annual ASCE Geotehcnial Spring Seminar, Long Beach, April 30,
2003
Southern California Earthquake Center (SCEC), "Recommended Procedures for lmplementation of
DMG Special Publication 1 17, Guidelines for Analyzing and IMitigating Liquefaction Hazards in
California", March, 1 999.
www. conservation.ca.gov/cgs/rghm/psha/fault_parameters/pdf/Documents/B_flt. pdf
Page 14
APPENDIX A FIELD INVESTIGATION
Subsurface conditions were explored by drilling hand auger boring to a maximum depth of 5 feet at
approximate locations shown on the enclosed Site Plan. Upon completion of excavating, the boreholes
were backfilled with onsite soils that were removed from the excavations.
The drilling of the test boring was supervised by a geotechnical engineer, who continuously logged the
borings and visually classified the soils in accordance with the Unifled Soil Classification System.
Page 15
GEOTECHNICAL LOG OF TEST HOLES
Test hole Number: BH-1
Hole Diameter: 4 inches
Equipment: Hand-Auger
DEPTH DESCRIPTION
oft -2.0ft Silty sand: Olive brown, moist, fine sand, medium dense.
3.0ft - sft Silty sand: Olive brown, moist, fine sand, dense
Total depth: 5 ft
No Caving
No free standing water
Hole back fill with on-site soil
Page 16
APPENDIX B LABORATORY TESTING
Expansion lndex
Expansion lndex test was conducted on the existing onsite near surface materials sampled during field
investigation. The test is performed in accordance with ASTM D-4829. The testing results are presented
below:
Corrosion Potential
Chemical laboratory test were conducted on the existing onsite near surface materials. The rests are
performed in accordance with California Test Method 417, 422,532 and 643. The resting results are
shown in table below:
Note: N/R= Not Requested
Sample Location Dry Density
( pcf)
Moisture
content (%)
Expansion
lndex
Classification
BH-1 @ 2.0'114 B Zero Very Low
Sample Location PH Sulfate Content
(% by Weiqht)
Min. Resistivity
(ohm-cm)
Chloride
Content (ppm)
BH-1 @ 0'to 2'7.3 0.0198 '1 ,894 4B
Page 17
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