HomeMy WebLinkAboutCDP 2020-0001; PATEL RESIDENCE; LIMITED GEOTECHNICAL INVESTIGATION; 2019-08-09EAST COUNTY SOIL CONSULTATION
AND ENGINEERING, INC.
10925 HARTLEY ROAD, SUITE "I"
SANTEE, CALIFORNIA 92071
(619) 258-7901
Fax 258-7902
Mr. Rajesh Patel
3170 Vista Way
Oceanside, California 92056
Subject: Limited Geotechnical Investigation
Proposed Single-Family Residence (Patel Residence)
Carlsbad Boulevard, APN 210-115-08
City of Carlsbad, California 92008
· Dear Mr. Patel:
August 9, 2019
Project No. 19-l 126G3
In accordance with your request, we have performed a limited geotechnical investigation at the
subject site to discuss the geotechnical aspects of the project and provide recommendations for the
proposed development.
Our investigation has found that the proposed building pad is underlain by approximately a 12-inch
layer of topsoil over dense terrace deposits to the maximum explored depth of 10 feet. It is our
opinion that the development of the proposed single-family residence is geotechnically feasible
provided the recommendations herein are implemented in the design and construction.
Should you have any questions with regard to the contents of this report, please do not hesitate to
contact our office.
Respectfully submitted,
ama ou a 1ou ia o, .E.
RCE 54071, GE 2704
MSD\md
Rajesh Patel/ Carlsbad Boulevard Project No. 19-1126G3
TABLE OF CONTENTS
INTRODUCTION .............................................................................................................................................. 3
SCOPE OF SERVICES ...................................................................................................................................... 3
SITE DESCRIPTION AND PROPOSED CONSTRUCTION ........................................................................ 3
FIELD INVESTIGATION AND LABORATORY TESTING ........................................................................ 4
GEOLOGY ......................................................................................................................................................... 4
Geologic Setting .................................................................................................................................... 4
Site Stratigraphy .................................................................................................................................... 4
SEISMICITY ...................................................................................................................................................... 5
Regional Seismicity .............................................................................................................................. 5
Seismic Analysis ................................................................................................................................... 5
2016 CBC Seismic Design Criteria ...................................................................................................... 6
Geologic Hazard Assessment ............................................................................................................... 6
GEOTECHNICAL EVALUATION .................................................................................................................. 7
Compressible Soils ................................................................................................................................ 7
Expansive Soils ..................................................................................................................................... 7
Groundwater .......................................................................................................................................... 7
CONCLUSIONS AND RECOMMENDATIONS ............................................................................................ 8
CLEARING AND GRUBBING ........................................................................................................................ 8
FOUNDATIONS AND SLABS ........................................................................................................................ 8
SETTLEMENT ................................................................................................................................................... 9
PRESATURA TION OF SLAB SUBGRADE .................................................................................................. 9
RETAINING WALLS ....................................................................................................................................... 9
PAVEMENTS .................................................................................................................................................. 10
Asphalt Concrete (AC) or Concrete (PCC) ......................................................................................... 10
Permeable Pavers (PJCP) .................................................................................................................... I 0
TEMPORARY SLOPES .................................................................................................................................. I I
TRENCH BACKFILL ..................................................................................................................................... 11
DRAINAGE ...................................................................................................................................................... 11
FOUNDATION PLAN REVIEW ................................................................................................................... 12
LIMITATIONS OF INVESTIGATION ......................................................................................................... 12
ADDITIONAL SERVICES ............................................................................................................................ 13
PLATES
Plate 1-Location of Exploratory Borings
Plate 2 -Summary Sheet (Exploratory Boring Logs) ....................................................................... 14
Plate 3 -USCS Soil Classification Chart
PAGE L-1, LABORATORY TEST RESULTS .............................................................................................. 15
REFERENCES ................................................................................................................................................. 16
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-//26G3
INTRODUCTION
This is to present the findings and conclusions of a limited geotechnical investigation for a
proposed two-story, single-family residence over a basement garage to be located on the east side
of Carlsbad Boulevard, in the City of Carlsbad, California.
The objectives of the investigation were to evaluate the existing soils conditions and provide
recommendations for the proposed development.
SCOPE OF SERVICES
The following services were provided during this investigation:
0 Site reconnaissance and review of published geologic, seismological and geotechnical reports
and maps pertinent to the project area
0 Subsurface exploration consisting of three (2) test pits within the limits of the proposed area of
development. The test pits were logged by our Staff Geologist.
0 Collection of representative soil samples at selected depths. The obtained samples were sealed
in moisture-resistant containers and transported to the laboratory for subsequent analysis.
0 Laboratory testing of samples representative of the types of soils encountered during the field
investigation
0 Geologic and engineering analysis of the field and laboratory data, which provided the basis
for our conclusions and recommendations
0 Production of this report, which summarizes the results of the above analysis and presents our
findings and recommendations for the proposed development
SITE DESCRIPTION AND PROPOSED CONSTRUCTION
The subject site is a rectangular-shaped residential lot located on the east side of Carlsbad
Boulevard, in the City of Carlsbad, California. The property, which encompasses an area of
approximately 7,245 square feet is vacant and gently sloping to the west. Vegetation consisted of
grass and ice plant. Site boundaries include Carlsbad Boulevard to the west, a vacant parcel to the
south and similar residential developments to the remaining directions.
The preliminary plans prepared by Design Decisions of Poway, California indicate the proposed
construction will include a single-family residence. The structure will be two-story, wood-framed
over a basement garage and founded on continuous footings with slab-on-grade floors. Associated
improvements will include a swimming pool, pavements and landscaping.
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-1126G3
FIELD INVESTIGATION AND LABO RA TORY TESTING
On June 18, 2019, three (3) test pits were excavated to a maximum depth of approximately 10 feet
below existing grade with a Caterpillar mini-excavator equipped with a 24-inch bucket. The
approximate locations of the test pits are shown on the attached Plate No. 1, entitled "Location of
Exploratory Test Pits". A continuous log of the soils encountered was recorded at the time of
excavation and is shown on Plate No. 2 entitled "Summary Sheet". The soils were visually and
texturally classified according to the filed identification procedures set forth on Plate No. 3 entitled
"USCS Soil Classification". Bulk soil samples were collected, sealed in moisture-resistant
containers and transported to the lab for testing.
Following the field exploration, laboratory testing was performed to evaluate the pertinent
engineering properties of the foundation materials. The laboratory-testing program included
moisture and density, particle size analysis and expansion index tests. These tests were performed
in general accordance with ASTM standards and other accepted methods. Page L-1 and Plate No. 2
provide a summary of the laboratory test results.
GEOLOGY
Geologic Setting
The subject site is located within the southern portion of what is known as the Peninsular Ranges
Geomorphic Province of California. The geologic map pertaining to the area (Reference No. 6)
indicates that the site is underlain by Pleistocene terrace deposits (Qt).
Site Stratigraphy
The subsurface descriptions provided are interpreted from conditions exposed during the field
investigation and/or inferred from the geologic literature. Detailed descriptions of the subsurface
materials encountered during the field investigation are presented on the exploration logs provided on
Plate No. 2. The following paragraphs provide general descriptions of the encountered soil types.
Topsoil
Topsoil is the surficial soil material that mantles the ground, usually containing roots and other organic
materials, which supports vegetation. Topsoil was observed in the test pits with a thickness of
approximately 12 inches. It consisted of dark brown, silty sand that was moist, loose and porous in
consistency with some organics (roots and rootlets).
Terrace Deposits (Qt)
Terrace deposits were underlying the topsoil layer. They generally consisted of reddish brown, sand
with silt and silty sand that were dry to moist and medium dense to dense in consistency.
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Rajesh Patel/ Carlsbad Boulevard Project No. l 9-l l 26G3
SEISMICITY
Regional Seismicity
Generally, Seismicity within California can be attributed to the regional tectonic movement taking
place along the San Andreas Fault Zone, which includes the San Andreas Fault and most parallel
and subparallel faults within the state. The portion of southern California where the subject site is
located is considered seismically active. Seismic hazards are attributed to groundshaking from
earthquake events along nearby or more distant Quaternary faults. The primary factors in
evaluating the effect an earthquake has on a site are the magnitude of the event, the distance from
the epicenter to the site and the near surface soil profile.
According to the Fault-Rupture Hazard Zones Act of 1994 (revised Alquist-Priolo Special Studies
Zones Act), quaternary faults have been classified as "active" faults, which show apparent surface
rupture during the last 11,000 years (i.e., Holocene time). "Potentially-active" faults are those faults
with evidence of displacing Quaternary sediments between 11,000 to 1,600,000 years old.
Seismic Analysis
Based on our evaluation, the closest known "active" fault is the Newport-Inglewood Fault located
approximately 6.2 kilometers (3.9 miles) to the west. The Newport-Inglewood Fault is the design fault
of the project due to the predicted credible fault magnitude and ground acceleration.
The Seismicity of the site was evaluated utilizing the 2008 National Hazard Maps from the USGS
website and Seed and Idriss methods for active Quaternary faults within a 50-mile radius of the
subject site. The site may be subjected to a Maximum Probable Earthquake of 7.5 Magnitude
along the Newport-Inglewood Fault, with a corresponding Peak Ground Acceleration of 0.45g.
The maximum Probable Earthquake is defined as the maximum earthquake that is considered likely
to occur within a 100-year time period.
The effective ground acceleration at the site is associated with the part of significant ground
motion, which contains repetitive strong-energy shaking, and which may produce structural
deformation. As such, the effective or "free field" ground acceleration is referred to as the
Repeatable High Ground Acceleration (RHGA). It has been determined by Ploessel and Slosson
(1974) that the RHGA is approximately equal to 65 percent of the Peak Ground Acceleration for
earthquakes occurring within 20 miles of a site. Based on the above, the calculated Credible
RHGA at the site is 0.29g.
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-1 l 2603
2016 CBC Seismic Design Criteria
A review of the active fault maps pertaining to the site indicates the location of the Newport-
Inglewood Fault Zone approximately 6.2 km to the west. Ground shaking from this fault or one of
the major active faults in the region is the most likely happening to affect the site. With respect to
this hazard, the site is comparable to others in the general area. The proposed residential structure
should be designed in accordance with seismic design requirements of the 2016 California Building
Code or the Structural Engineers Association of California using the following seismic design
parameters:
PARAMETER VALUE 2016 CBC and ASCE 7 REFERENCES
Site Class D Table 20.3-1/ ASCE 7, Chapter 20
Mapped Spectral Acceleration For Short Periods, 1.173g Figure 1613.3.l(l)
Ss
Mapped Spectral Acceleration For a I -Second 0.451g Figure 1613.3.1(2)
Period, S1
Site Coefficient, Fa 1.031 Table 1613.3.3(1)
Site Coefficient, Fv 1.549 Table 1613.3.3(2)
Adjusted Max. Considered Earthquake Spectral 1.209g Equation 16-37
Response Acceleration for Short Periods, SMs
Adjusted Max. Considered Earthquake Spectral 0.699g Equation 16-38
Response Acceleration for I -Second Period, SM1
5 Percent Damped Design Spectral Response 0.806g Equation 16-39
Acceleration for Short Periods, Sos
5 Percent Damped Design Spectral Response 0.466g Equation 16-40
Acceleration for I -Second Period, S0 1
Geologic Hazard Assessment
Ground Rupture
Ground rupture due to active faulting is not considered likely due to the absence of known fault traces
within the vicinity of the project; however, this possibility cannot be completely ruled out. The
unlikely hazard of ground rupture should not preclude consideration of "flexible" design for on-site
utility lines and connections.
Liquefaction
Liquefaction involves the substantial loss of shear strength in saturated soils, usually sandy soils with a
loose consistency when subjected to earthquake shaking. Based on the absence of shallow
groundwater and consistency of the underlying terrace deposits, it is our opinion that the potential for
liquefaction is very low.
Landsliding
There is no indication that landslides or unstable slope conditions exist on or adjacent to the project
site. There are no obvious geologic hazards related to landsliding to the proposed development or
adjacent properties.
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Rajesh Patel/ Carlsbad Boulevard Project No. /9-1126G3
Tsunamis and Seiches
The site is not subject to inundation by tsunamis due to its elevation. The site is also not subject to
seiches (waves in confined bodies of water).
GEOTECHNICAL EVALUATION
Based on our investigation and evaluation of the collected information, we conclude that the proposed
construction is feasible from a geotechnical standpoint provided the recommendations provided herein
will be properly implemented during structural development.
It is our understanding that the basement garage of the proposed structure will be excavated into the
dense terrace deposits. Therefore, no remedial grading will be required. The new foundations may
consist of reinforced continuous and/ or spread footings with reinforced slabs. Recommendations and
criteria for foundation design are provided in the Foundation and Slab recommendations section ofthis
report.
Compressible Soils
Our field observations and testing indicate low compressibility within the dense terrace deposits,
which underlie the site at shallow depths. However, loose topsoil was encountered to a depth of
approximately 12 inches below surface grades. These soils which are compressible will not impact the
proposed construction because the basement will be excavated into the dense terrace deposits.
Following implementation of the recommendations presented herein, the potential for soil
compression resulting from the new development has been estimated to be low. The low-settlement
assessment assumes a well-planned and maintained site drainage system.
Expansive Soils
An expansion index test was performed on a select sample of the terrace deposits to determine
volumetric change characteristics with change in moisture content. An expansion index of O was
obtained which indicates a very low expansion potential for the foundation soils.
Groundwater
Static groundwater was not encountered to the depths of the test pits. The subject site is located at
an elevation over 50 feet above Mean Sea Level. We do not expect groundwater to affect the
proposed construction. Recommendations to prevent or mitigate the effects of poor surface
drainage are presented in the Drainage section of this report.
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Rajesh Patel/ Carlsbad Boulevard Project No. I 9-I I 26G3
CONCLUSIONS AND RECOMMENDATIONS
The following conclusions and recommendations are based upon the analysis of the data and
information obtained from our soil investigation. This includes site reconnaissance; field
investigation; laboratory testing and our general knowledge of the soils native to the site. The site is
suitable for the proposed residential development provided the recommendations set forth are
implemented during construction.
CLEARING AND GRUBBING
The area of the proposed construction should be cleared of vegetation and deleterious materials.
Vegetation and debris from the clearing operation should be properly disposed of off-site. The area
should be thoroughly inspected for any possible buried objects, which need to be rerouted or removed
prior to construction. All holes, trenches, or pockets left by the removal of these objects should be
properly backfilled with compacted fill materials.
Our field investigation indicates that dense terrace deposits underlie the site at shallow depths.
These soils will be adequate for the support of the proposed structure without detrimental
settlement. Foundation excavations should be observed by our representative to verify competent
bearing soils.
FOUNDATIONS AND SLABS
a. Continuous and spread footings are suitable for use and should extend to a minimum depth of 24
inches below the lowest adjacent grade into the dense terrace deposits. Continuous footings should
be at least 18 inches wide and reinforced with a minimum of four #4 steel bars; two bars placed
near the top of the footings and the other two bars placed near the bottom of the footings. Isolated
or spread footings should have a minimum width of 24 inches. Their reinforcement should consist
of a minimum of #4 bars spaced 12 inches on center (each way) and placed horizontally near the
bottom. The minimum reinforcement recommended is based on soil characteristics and is not
intended to supersede the structural engineer requirements.
b. Interior concrete floor slabs should be a minimum 5 inches thick. Reinforcement should consist
of #3 bars placed at 16 inches on center each way within the middle third of the slabs by supporting
the steel on chairs or concrete blocks "dobies". The slabs should be underlain by 2 inches of clean
sand over a 10-mil visqueen moisture barrier. The effect of concrete shrinkage will result in cracks
in virtually all-concrete slabs. To reduce the extent of shrinkage, the concrete should be placed at a
maximum of 4-inch slump. The minimum steel recommended is not intended to prevent shrinkage
cracks. Actual slab thickness and reinforcement may be designed by the project structural engineer
using a coefficient of subgrade reaction of 225 pci.
c. Where moisture-sensitive floor coverings are anticipated over the slabs, the 10-mil plastic
moisture barrier should be underlain by a capillary break at least 2 inches thick, consisting of
coarse sand, gravel or crushed rock not exceeding 3/4 inch in size with no more than 5 percent
passing the #200 sieve.
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-l J 26G3
d. An allowable soil bearing value of 2,000 pounds per square foot may be used for the design of
continuous and spread footings at least 12 inches wide and founded a minimum of 12 inches into
the dense terrace deposits. This value may be increased by 400 psf for each additional foot of depth
or width to a maximum value of 6,000 lb/ft2.
e. Lateral resistance to horizontal movement may be provided by the soil passive pressure and the
friction of concrete to soil. An allowable passive pressure of 300 pounds per square foot per foot
of depth may be used. A coefficient of friction of 0.35 is recommended. The soils passive pressure
as well as the bearing value may be increased by I /3 for wind and seismic loading.
SETTLEMENT
Since footings for the proposed structure are anticipated to be supported by the dense terrace
deposits, total and differential settlement should be within acceptable limits. For design purposes, a
differential settlement up to one-half (1 /2) inch and a total settlement up to three-quarter (3 /4) inch
across the structural span may be used.
PRESATURATION OF SLAB SUBGRADE
Because of the granular characteristics of the surficial soils, presoaking of subgrade prior to
concrete pour is not required. However, subgrade soils in areas receiving concrete should be
watered prior to concrete placement to mitigate any drying shrinkage, which may occur following
foundation excavation.
RETAINING WALLS
Cantilevered retaining walls should be designed for an "active" lateral earth pressure of 35 psf/ft (35
pcf EFP) for approved granular and level backfill conditions. Cantilever walls subject to uniform
surcharge loads should be designed for an additional uniform lateral pressure equal to one-third (1 /3)
the anticipated surcharge pressure.
Restrained walls such as basement walls should be designed utilizing an "at-rest" earth pressure of 60
psf/ft (60 pcf EFP) for approved granular and level backfill conditions. Restrained walls subject to
uniform surcharge loads should be designed for an additional uniform lateral pressure equal to one-
half (1 /2) the anticipated surcharge.
For earthquake motions, additional lateral pressures of 26 and 39 pcf (EFP) may be applied for non
restrained and restrained conditions respectively using an inverted triangular distribution if required.
Soil design criteria, such as bearing capacity, passive earth pressure and sliding resistance as
recommended under the Foundation and Slab recommendations section, may be incorporated into the
retaining wall design.
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Rajesh Patel/ Carlsbad Boulevard Project No. l 9-/ J 26G3
Footings should be reinforced as recommended by the structural engineer and appropriate back
drainage provided to avoid excessive hydrostatic wall pressures. As a minimum we recommend a
fabric-wrapped crushed rock and perforated pipe system. At least 2 cubic feet per linear foot of free-
drainage crushed rock should be provided.
The remaining wall backfill should consist of approved granular material. This fill material should
be compacted to a minimum relative compaction of 90 percent as determined by ASTM D-1557
test method. Flooding or jetting of backfill should not be permitted. Granular backfill should be
capped with 18 inches (minimum) of relatively impervious fill to seal the backfill and prevent
saturation. It should be noted that the use of heavy compaction equipment in close proximity to
retaining structures can result in wall pressures exceeding design values and corresponding wall
movement greater than that associated with active or at-rest conditions. In this regard, the
contractor should take appropriate precautions during the backfill placement.
PAVEMENTS
Asphalt Concrete (AC) or Concrete (PCC)
Based on an estimated R-value of 50, and in conformance with Caltrans Standard Flexible
Pavement Design Procedures, the following pavement sections for the assumed traffic index were
obtained. The actual design and adoption relative to allowable road gradients should be developed
by the civil designer based on the jurisdictional requirements.
Location Traffic Index Pavement Section
Driveway 5.0 3.0" AC over 4.0" AB
or
6" PCC on Compacted Subgrade
The upper 12 inches of subgrade should be moisture-conditioned within 2 percent over optimum
and compacted to at least 95 percent relative compaction (ASTM D1557). Aggregate base should
also be compacted to a minimum of 95 percent relative compaction. PCC pavements should be a
minimum of 3,500 psi concrete. It is recommended that steel reinforcement be provided for PCC
pavements which will be subject to heavy impact loading, such as trash and fire trucks. Minimum
reinforcement should consist of #3 deformed rebar placed at 18-inch centers each way. Placement
of concrete, control/ expansion joints, and any reinforcement should be conformance with ACI
specifications and the Structural Engineer's design.
Permeable Pavers (PICP)
Based on the type and consistency of the subgrade soils, the following permeable interlocking
concrete pavement section is recommended in accordance with the Interlocking Concrete Pavement
Institute (ICPI) specifications.
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-1126G3
• Minimum 3 1/8 -inch pervious concrete pavers
• 1 .5'' to 2"-inch bedding course (Typ. No. 8 Aggregate)
• 4-inch No . 57 stone open-graded base
• 6-inch No. 2 stone subbase wrapped in Mirafi 180N geotextile or equivalent
Compaction of subgrade soils should be conducted as specified for asphalt or concrete pavements
above.
TEMPORARY SLOPES
For the excavation of the basement, foundations or utility trenches, temporary vertical cuts to a
maximum height of 4 feet may be constructed in natural soils. Any temporary cuts beyond the above
height constraints should be shored or further laid back following a 1: 1 (horizontal to vertical) slope
ratio. OSHA guidelines for trench excavation safety should be implemented during construction.
The plot plan indicates that the proposed basement wall on the north side is located at the property
line. Therefore shoring will be required and may be designed with the following soil parameters:
• Active Pressure
• Passive Pressure
• Coefficient of Friction
TRENCH BACKFILL
3 0 psf/ft (3 0 pcf EFP)
300 psf/ft (300 pcf EFP)
0.35
Excavations for utility lines, which extend under structural areas should be properly backfilled and
compacted. Utilities should be bedded and backfilled with clean sand or approved granular soil to
a depth of at least one foot over the pipe. This backfill should be uniformly watered and
compacted to a firm condition for pipe support. The remainder of the backfill should be on-site
soils or non-expansive imported soils, which should be placed in thin lifts, moisture-conditioned
and compacted to at least 90% relative compaction.
DRAINAGE
Adequate measures should be undertaken after the structure and other improvements are in place,
such that the drainage water within the site and adjacent properties is directed away from the
foundations, footings, floor slabs and the tops of slopes via rain gutters, downspouts, surface swales
and subsurface drains towards the natural drainage for this area. In accordance with the 2016
California Building Code, a minimum gradient of 2 percent is recommended in hardscape areas
adjacent to the structure. In earth areas, a minimum gradient of 5 percent away from the structure
for a distance of at least 10 feet should be provided. If this requirement cannot be met due to site
limitations, drainage can be done through a swale in accordance with Section 1804.4 of the 2016
California Building Code. Earth swales should have a minimum gradient of 2 percent. Drainage
should be directed to approved drainage facilities. Proper surface and subsurface drainage will be
required to minimize the potential of water seeking the level of the bearing soils under the
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-I I 26G3
foundations, footings and floor slabs, which may otherwise result in undermining and differential
settlement of the structure and other improvements.
FOUNDATION PLAN REVIEW
Our firm should review the foundation plan during the design phase to assure conformance with the
intent of this report. During construction, foundation excavations should be observed by our
representative prior to the placement of forms, reinforcement or concrete for conformance with the
plans and specifications.
LIMITATIONS OF INVESTIGATION
Our investigation was performed using the skill and degree of care ordinarily exercised, under similar
circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No
other warranty, expressed or implied, is made as to the conclusions and professional advice included in
this report. This report is prepared for the sole use of our client and may not be assigned to others
without the written consent of the client and ECSC&E, Inc.
The samples collected and used for testing, and the observations made, are believed representative of
site conditions; however, soil and geologic conditions can vary significantly between exploration
trenches, boreholes and surface exposures. As in most major projects, conditions revealed by
construction excavations may vary with preliminary findings. If this occurs, the changed conditions
must be evaluated by a representative of ECSC&E and designs adjusted as required or alternate
designs recommended.
This report is issued with the understanding that it is the responsibility of the owner, or of his
representative to ensure that the information and recommendations contained herein are brought to the
attention of the project architect and engineer. Appropriate recommendations should be incorporated
into the structural plans. The necessary steps should be taken to see that the contractor and
subcontractors carry out such recommendations in the field.
The findings of this report are valid as of this present date. However, changes in the conditions of a
property can occur with the passage of time, whether they are due to natural processes or the works of
man on this or adjacent properties. In addition, changes in applicable or appropriate standards may
occur from legislation or the broadening of knowledge. Accordingly, the findings of this report may
be invalidated wholly or partially by changes outside of our control. Therefore, this report is subject to
review and should be updated after a period of two years.
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Rajesh Patel/ Carlsbad Boulevard Project No. 19-l l 26G3
ADDITIONAL SERVICES
The review of plans and specifications, field observations and testing under our direction are integral
parts of the recommendations made in this report. If East County Soil Consultation and Engineering,
Inc. is not retained for these services, the client agrees to assume our responsibility for any potential
claims that may arise during construction. Observation and testing are additional services, which are
provided by our firm, and should be budgeted within the cost of development.
Plates No. 1 through 3, Page L-1 and References are parts of this report.
13
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EAST COUNTY SOIL CONSULTATION
& ENGINEERING, INC.
10925 HARTLEY RD., SUITE I
SANTEE, CA 92071
GEOTECHNICAL ENGINEERING
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DEPTH
Surface
1.0'
2.0'
3.0'
4.0 '
5.0'
7.0'
8.0'
10.0'
Rajesh Patel/ Carlsbad Boulevard Project No. 19-1126G3
PLATEN0.2
SUMMARY SHEET
TEST PIT NO. 1
SOIL DESCRIPTION
TOPSOIL
dark brown, dry, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, dry to moist, medium dense to dense, silty sand
" " " " " "
y
117.1
reddish brown, dry to moist, medium dense to dense, sand with silt
" " " " " " 115.7
becomes light reddish brown and moist
" " " " "
" " " " "
bottom of test pit, no caving, no groundwater
test pit backfilled 6/18/19
"
"
112.6
115.4
M
3.0
5.0
5.3
6.2
----------------------------------------------------------------------------------------------------------------------------------
DEPTH
Surface
1.0'
2.0'
3.0'
5.0'
6.0'
DEPTH
Surface
1.0'
2.0'
3.0'
5.0'
6.0'
TEST PIT NO. 2
SOIL DESCRIPTION
TOPSOIL
dark brown, dry, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, dry to moist, medium dense to dense, silty sand
" " " " " "
y
115.3
reddish brown, dry to moist, medium dense to dense, sand with silt
" " " " " " 120.4
bottom of test pit, no caving, no groundwater
test pit backfilled 6/18/19
TEST PIT NO. 3
SOIL DESCRIPTION
TOPSOIL
dark brown, dry, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, dry, medium dense, silty sand
" " " " " "
y
108.9
reddish brown, dry to moist, medium dense to dense, sand with silt
becomes light reddish brown and moist
bottom of test pit, no caving, no groundwater
test pit backfilled 6/18/19
M
2.5
4.7
M
3.3
Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN %
14
SOIL CLASSIFICATION CHART -
COARSE
GRAINED
SOILS
MORE THAN 50%
OF MATERIAL IS
LARGER THAN NO.
200 SIEVE SIZE
FINE
GRAINED
SOILS
MORE THAN 50%
OF MATERIAL IS
SMALLER THAN NO.
200 SIEVE SIZE
MAJOR DIVISIONS
GRAVEL
AND
GRAVELLY
SOILS
MORE THAN 50%
OF COARSE
FRACTION
RETAINED ON NO. 4
SIEVE
SAND
AND
SANDY
SOILS
MORE THAN 50%
OF COARSE
FRACTION PASSING
ON NO. 4 SIEVE
SILTS
AND
CLAYS
SILTS
AND
CLAYS
CLEAN GRAVELS
(LITTLE OR NO FINES)
GRAVELS WITH
FINES
(APPRECIABLE AMOUNT
OF FINES)
CLEAN SANDS
(LITTLE OR NO FINES)
SANDS WITH
FINES
(APPRECIABLE AMOUNT
OF FINES)
UOUIDLIMIT
LESS THAN 50
LIQUID LIMIT
GREATER THAN 50
HIGHLY ORGANIC SOILS
SYMBOLS
GRAPH LETTER
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
CL
MH
CH
OH
--L.!'
PT
TYPICAL
DESCRIPTIONS
WELL-GRADED GRAVELS. GRAVEL -
SAND MIXTURES, LITTLE OR NO FINES
POORL Y-GRAOED GRAVELS, GRAVEL -
SANO MIXTURES. LITTLE OR NO FINES
SIL TY GRAVELS, GRAVEL -SAND -SILT
MIXTURES
CLAYEY GRAVELS, GRAVEL -SAND -
CLAY MIXTURES
WELL-GRADED SANDS, GRAVELLY
SANDS, LITTLE OR NO FINES
POORLY-GRADED SANDS, GRAVELLY
SANO, LITTLE OR NO FINES
SIL TY SANOS, SAND -SILT MIXTURES
CLAYEY SANOS, SAND-CLAY
MIXTURES
INORGANIC SILTS AND VERY FINE
SANDS, ROCK FLOUR, SIL TY OR
CLAYEY FINE SANDS OR CLAYEY SILTS
WITH SLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO MEDIUM
PLASTICITY, GRAVELLY CLAYS, SANDY
CLAYS, SILTY CLAYS, LEAN CLAYS
ORGANIC SILTS AND ORGANIC SIL TY
CLAYS OF LOW PLASTICITY
INORGANIC SIL TS, MICACEOUS OR
OIATOMACEOUS FINE SANO OR SILTY
SOILS
INORGANIC CLAYS OF HIGH PLASTICITY
ORGANIC CLAYS OF MEDIUM TO HIGH
PLASTICITY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH
HIGH ORGANIC CONTENTS
NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS
CLASSIFICATION RANGE OF GRAIN SIZES
U.S. STANDARD GRAIN SIZE IN
SIEVE SIZE MILLIMETERS
BOULDERS Above I 2 Inches Above 305
COBBLES 12 Inches To 3 Inches 305 To 76.2
GRAVEL 3 Inches to No. 4 76.2 to 4.76
Coarse 3 Inches to¾ Inch 76.2to 19.I
Fine ¾ Inch to No. 4 19.lto4.76
SAND No. 4 to No. 200 4. 76 to 0.074
Coarse No. 4 to No. IO 4.76 to 2.00
Medium No. IO to No. 40 2.00 to 0.420
Fine No. 40 to No. 200 0.420 to 0.074
SILT AND CLAY Below No. 200 Below 0.074
GRAIN SIZE CHART
EAST COUNTY SOIL CONSULTATION
& ENGINEERING, INC.
I 0925 HAR1LEY RD .• SUITE I, SANTEE. CA .92071
(619) 258-7901 Fax C619) 258-7902
" ~ 50
i 40 l--+-+---t--f-----lr---+--t7"'---t---t-----l
~ 30 l---+-4--;,C--+----11--..,;,c.-+--+-+---I
!!! ~ 20 --~,1<--+-+-"'9------;---;-, -+--t
MH&OH I
10 ~;:;;;;;;;;;;;~-t--i~--r---r1----r-1
10 2.0 30 4.0 so 60 70 80 90 100
LlOUIO LIMIT (LL), ~
PLASTICITY CHART
J: /Al e-s11 f>A-Ti!:Z-MP✓ecr
C:~L,58,H> .BaJLE ///h(? I)
INITIAL
MOISTURE
CONTENT(%)
9.7
U.S. Standard
Sieve Size
l "
1/2"
3/8"
#4
#8
#16
#30
#50
#100
#200
uses
Rajesh Patel/ Carlsbad Boulevard Project No. 19-I J 26G3
PAGE L-1
LABORATORY TEST RESULTS
EXP ANSI ON INDEX TEST (ASTM D4829)
SATURATED
MOISTURE
CONTENT(%)
18.2
INITIAL DRY
DENSITY EXPANSION
(PCF) INDEX
112.0 0
PARTICLE SIZE ANALYSIS (ASTM D422)
Percent Passing Percent Passing
TP-2@2.0' TP-1 @4.0'
Terrace Deposits Terrace Deposits
--
--
--
--
--
100 100
91 91
44 41
17 17
12.2 11
SM SP-SM
15
LOCATION
TP-1 @ 4.0'
Percent Passing
TP-2@ 10.0'
Terrace Deposits
-
-
-
-
-
100
89
42
17
11
SP-SM
Rajesh Patel/ Carlsbad Boulevard Project No. 19-112603
REFERENCES
1. "2016 California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of2",
Published by International Code Council.
2. "Geologic Map of the San Diego 30' x 60' Quadrangle, California", by Michael P. Kennedy and
Siang S. Tan, 2008.
3. "Geotechnical and Foundation Engineering: Design and Construction", by Robert W. Day, 1999.
4. "1997 Uniform Building Code, Volume 2, Structural Engineering Design Provisions", Published by
International Conference of Building Officials.
5. "Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada to
be used with 1997 Uniform Building Code", Published by International Conference of Building
Officials.
6. "Geologic Maps of the Northwestern Part of San Diego County, California", Department of
Conservation, Division of Mines and Geology, by Siang S. Tan and Michael P. Kennedy, 1996.
7. "Bearing Capacity of Soils, Technical Engineering and Design Guides as Adapted from the US
Army Corps of Engineers, No. 7", Published by ASCE Press, 1994.
8. "Foundations and Earth Structures, Design Manual 7.2", by Department of Navy Naval Facilities
Engineering Command, May 1982, Revalidated by Change l September 1986.
9. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and l.M. Idriss, 1982.
I 0. "Geology of the San Diego Metropolitan Area, California", Bulletin 200, by Michael P. Kennedy
and G.L. Peterson, 1975.
16