HomeMy WebLinkAboutCDP 2017-0021; OCEAN STREET RESIDENCE; LIMITED GEOTECHNICAL INVESTIGATION; 2017-03-02Mr. Alan Shafran
1673 Amante Court
Carlsbad, California 92011
EAST COUNTY SOIL CONSULTATION
AND ENGINEERING, INC.
10925 HARTLEY ROAD, SUITE "I"
SANTEE, CALIFORNIA 92071
(619) 258-7901
Fax 258-7902
Subject: Limited Geotechnical Investigation
Proposed Single-Family Residence
2680 Ocean Street
City of Carlsbad, Calitomia 92008
Dear Mr. Shafran:
March 2, 2017
Project No. 17-110605
PR.o.l~c, 1D; CDP2017--0?2-i
~WC,, )to : OtJG. .S-10 -CIA
G tt .So G~ 2011? • oao"
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 residential development.
Our investigation has found that the proposed building pad is underlain by an approximately 6 to
12-inch layer of topsoil over moderately dense to dense terrace deposits to the explored depth of 7
feet. It is our opinion that the construction of the proposed residence is geotechnically feasible
provided the recommerndations 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.
Mamadou Saliou Diallo, P.E.
RCE 54071, GE 2704
MSD/md
RECEIVED
FEB O 5 2018
LAND DEVELOPMENT
ENGINEERING
ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
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 Seismi~ity ............................................................................................................................... 5
Seismic Analysis ................................................................................................................................... 5
201 6 CBC Seismic Design Criteria ...................................................................................................... 6
Geologic Ha.zard.Assessment. ............................................................................................................... 6
GEOTECHNICAL EVALUATION .................................................................................................................. 7
Compressible Soils ................................................................................................................................ 7
Expansive Soils ...................................................................................................................................... 7
Groundwater .......................................................................................................................................... 7
CONCLUSIONS AND RECOMMENDATIONS ............................................................................................ 8
GRADING AND EARTHWORK ...................................................................................................................... 8
Clearing and Grubbing .......................................................................................................................... 8
Structural Improvement of Soils ............................................................................................................ 8
Transitions Between Cut and Fill ......................................................................................................... 9
Method and Criteria of Compaction .................................................................................................... ,. 9
Erosion Control ...................................................................................................................................... 9
Standard Grading Guidelines ................................................................................................................. 9
FOUNDATIONS AND $LABS ........................................................................................................................ 9
SETTLEMENT ................................................................................................................................................. 10
PRESATURATION OF SLAB SUBGRADE ................................................................................................. 10
TEMPORARY SLOPES .................................................................................................................................. I 0
TRENCH BACKFILL ...................................................................................................................................... 11
DRAINAGE ...................................................................................................................................................... 11
FOUNDATION PLAN REVIEW .................................................................................................................... 11
LIMITATIONS OF WVESTIGATION ......................................................................................................... 11
ADDITIONAL SERVICES ............................................................................................................................ 12
PLATES
Plate 1-Location of Exploratory Boreholes
Plate 2 -Summary Sheet (Exploratory Borehole Logs ...................................................................... 13
Plate 3 -USCS Soil Classification Chart
PAGE L-1, LABORATORY TEST RESULTS .............................................................................................. 14
REFERENCES ................................................................................................................................................. 15
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ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
INTRODUCTION
This is to present the findings and conclusions of a limited geotechnical investigation for the
proposed single-family residence to be located at 2680 Ocean Street, 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 four ( 4) boreholes within the limits of the proposed area
of development. The boreholes 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 an rectangular-shaped residential lot located on the east side of Ocean Street, in
the City of Carlsbad, California. The property which encompasses an area of approximately 3,500
square feet (70' x 50') is occupied by a one-story, single-family residence with a detached garage.
The site is gently sloping to the west. Vegetation consisted of grass, shrub and a few trees. The
parcel is bordered by Ocean Street to the west and similar residential developments to the
remaining directions.
The site plan prepared by Wright Design of Carlsbad, California indicates that the proposed
construction will consist of a single-family residence including an accessory dwelling unit
following demolition of the existing structures. The new structure will be two-story, wood-framed
and founded on continuous footings with a slab-on-grade floor.
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ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
FIELD INVESTIGATION AND LABO RA TORY TESTING
On February 16, 2017, four (4) boreholes were excavated to a maximum depth of approximately 7
feet below existing grade with a hand auger. The approximate locations of the boreholes are shown
on the attached Plate No. 1, entitled "Location of Exploratory Boreholes". 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".
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. 5)
indicates that the site is underlain by Pleistocene terrace deposits (Qt).
Site Stratigraphy
The subsurface descriptions provided are interpreted from conditions exposed dwing 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 provid~d 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 observed in the boreholes was approximately 6 to 12
inches thick and consisted of dark brown, silty sand that was dry, loose and porous in consistency with
some organics (rootlets).
Terrace Deposits (Qt)
Terrace deposits were underlying the topsoil. They generally consisted of reddish brown, silty sand
that was moist and medium dense to dense in consistency.
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ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.17-1106D5
SEISMICITY
Re2ional 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 and 1.6 million years old.
Seismic Analysis
Based on our evaluation, the closest known "active" fault is the Rose Canyon Fault located
approximately 7 kilometers (4.4 miles) to the west. The Rose Canyon Fault is the design fault of the
project due to the predicted credible fault magnitude and groWld 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 6.9 Magnitude
along the Rose Canyon 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 stru¢tural
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.
2016 CBC Seismic Design Criteria
A review of the active fault maps pertaining to the site indicates the location of the Rose Canyon
Fault Zone approximately 7 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 single-family residence
should be designed in accordance with seismic design requirements of the 2016 California Building
5
ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
Code or the Structural Engineers Association of California using the following seismic d~sign
parameters:
PARAMlITER
Site Class
Mapped Spectral Acceleration For Short Periods,
Ss
Mapped Spectral Acceleration For a I-Second
Period, S1
Site Coefficient Fa
Site Coefficient, Fv
Adj usted Max. Considered Earthquake Spectral
Response Acceleration for Short Periods, SMs
Adjusted Max. Considered Earthquake Spectral
Response Acceleration for I-Second Period. SM1
5 Percent Damped Design Spectral Response
Acceleration for Short Periods, Sos
5 Percent Damped Design Spectral
Acceleration for I-Second Period, S01
Geologic Hazard Assessment
Ground Rupture
Response
VALUE 2016 CBC & ASCE 7 REFERENCES
D Table 20.3-1/ ASCE 7, Chapter 20
1.174g Figure 161 3.3.1(1)
0.451g Figure 16 13.3.1(2)
1.030 Table 1613.3.3(1)
1.549 Table 1613.3.3(2)
1.210g Equation 16-37
0.698g Equation 16-38
0.807g Equation 16-39
0.466g Equation 16-40
Ground rupture due to active faulting is not considered likely due to the absence of known fault ttaces
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 oljl.-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 sh4llow
groundwater and consistency of the underlying bedrock materials, it is our opinion that the pot~ntial
for liquefaction is very low.
Landsliding
There is no indication that landslides or unstable slope conditions exist on or adjacent to the prpject
site. There are no obvious geologic hazards related to landsliding to the proposed developm{1nt or
adjacent properties.
Tsunamis and Seiches
The site is not subject to inundation by tsunamis due to its elevation. The site is also not subj<rct to
seiches (waves in confined bodies of water).
6
.
ALAN SHAFRAN! 2680 OCEAN STREET PROJECT NO. 17-1106D5
GEOTECHNICAL EVALUATION
Based on our investigation and evaluation of the collected infonnation, we conclude that the proposed
residential development is feasible from a geotechnical standpoint provided the recommendations
herein will be properly implemented during construction.
In order to provide a unifonn support for the proposed structure, footings should be excavated into
properly compacted fill soils or extended to the dense terrace deposits. The new foundation may
consist of reinforced continuous footings with reinforced slabs. Recommendations and criterift for
foundation design are provided in the Foundation and Slab recommendations section of this report.
Compressible Soils
Our field observations and testing indicate low compressibility within the dense terrace deppsits,
which underlie the site. However, loose topsoil and moderately dense terrace deposits were
encountered to a depth of approximately 3 feet below surface grades. These soils are compressible
and should be overexcavated and recompacted unless footings are extended to the dense Le'rrace
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. Recommendations
regarding mitigation by earthwork construction are presented in the Grading and Earthwork
Recommendations section of this report.
Expansive Soils
An expansion index test was perfonned on a representative 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 boreholes. The building pad is located
at an elevation over 40 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.
CONCLUSIONS AND RECOMMENDATIONS
The following conclusions and recommendations are based upon the analysis of the data and
infonnation 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.
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ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
GRADING AND EARTHWORK
Based upon the proposed site plan and the information obtained during the field investigation, we
anticipate that the proposed structure will be founded on continuous footings, which are supported by
properly compacted fill or dense terrace deposits. The following grading and earthwork
recommendations are based upon the limited geotechnical investigation performed, and should be
verified during construction by our field representative.
Clearing and Grubbiqg
The area to be graded or to receive fill and/or structure should be cleared of vegetation and waste from
the demolition of the existing structures. Vegetation and the debris from the clearing operation should
be properly disposed of off-site. The area should be thoroughly inspected for any possible buried
o~jects, which need to be rerouted or removed prior to the inception of, or during grading. All boles,
trenches, or pockets left by the removal of these objects should be properly backfilled with compacted
fill materials as recommended in the Method and Criteria of Compaction section of this report.
Structural Improvement of Soils
Information obtained firom our field and laboratory analysis indicates that loose topsoil and moderately
dense terrace deposits eover the building pad to a depth of approximately 3 feet below existing grade.
These surficial soils are susceptible to settlement upon loading. Based upon the soil characteristics,
we recommend the following:
*
*
*
*
All topsoil and other loose natural soils should be removed from areas, which are planned to
receive compacted fills and/or structural improvements. The bottom of the removal area
should expose competent materials as approved by ECSC&E geotechnical representative.
Prior to the placement of new fill, the bottom of the removal area should be scarified a
minimum depth of 6 inches, moisture-conditioned within 2 percent above the optjmurn
moisture content, and then recompacted to at least 90 percent relative compaction (ASTM
D1557 test method).
Overexcavation should be completed for the structural building pad to a minimum depth of
2 feet below the bottom of the proposed footings. The limit of the required wea of
overexcavation should be extended a minimum of 5 feet laterally beyond the perimeter
footing (building footprint).
Soils utilized as fill should be moisture-conditioned and recompacted in conformance with the
following Method and Criteria of Compaction section of this report. The actual depth and
extent of any overexcavation and recompaction should be evaluated in the field by a
representative ofECSC&E.
An alternative to the overexcavation and recompaction of subgrade is to extend footings for
the proposed structure to the dense terrace deposits. However, for slab support, we
recommend overexcavation and recompaction of the upper 2 feet of subgrade.
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ALAN SHAFRAN! 2680 OCEAN STREET PROJECT NO. 17-1106D5
Transitions Between Cut and Fill
The proposed structure is anticipated to be founded in either properly compacted fill or dense terrace
deposits. Cut to fill transitions below the proposed structure should be completely eliminated d,uring
the earthwork construction as required in the previous section.
Method and Criteria pf Compaction
Compacted fills should, consist of approved soil material, free of trash debris, roots, vegetation or other
deleterious materials. Fill soils should be compacted by suitable compaction equipment in uniform
loose lifts of 6 to 8 inches. Unless otherwise specified, all soils subjected to recompaction sho'1ld be
moisture-conditioned within 2 percent over the optimum moisture content and compacted to at least
90 percent relative compaction per ASTM test method D1557.
On-site soils, after being processed to delete the aforementioned deleterious materials, may be used for
recompaction purposes. Should any importation of fill be planned, the intended import source(s)
should be evaluated and approved by ECSCE prior to delivery to the site. Care should be taken to
ensure that these soils aire not detrimentally expansive.
Erosion Control
Due to the granular characteristics of on-site soils, areas of recent grading or exposed ground may be
subject to erosion. During construction, surface water should be controlled via berms, gxavel/
sandbags, silt fences, straw wattles, siltation and bioretention basins, positive surface grades or other
method to avoid damage to the finish work or adjoining properties. All site entrances and exits imust
have coarse gravel or steel shaker plates to minimize offsite sediment tracking. Best Management
Practices (BMPs) must be used to protect storm drains and minimize pollution. The contractor
should take measures tp prevent erosion of graded areas until such time as permanent drainage and
erosion control measunes have been installed. After completion of grading, all excavated surfaces
should exhibit positive drainage and eliminate areas where water might pond.
Standard Grading G~idelines
Grading and earthwork should be conducted in accordance with the standard-of-practice methods for
this local, the guidelines of the current edition of the California Building Code, and the requirements
of the jurisdictional agency. Where the information provided in the geotechnical report differs from
the Standard Grading Guidelines, the requirements outlined in the report shall govern.
FOUNDATIONS AND SLABS
a. Continuous and spr~ad footings are suitable for use and should extend to a minimwn depth 9 f 18
inches for the proposed two-story structure into the properly compacted fill soils or dense terrace
deposits. Continuous :footings should be at least 15 inches in width 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)
9
ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
and placed horizontally near the bottom. These recommendations are based on geotechnical
considerations and are not intended to supersede the structural engineer requirements.
b. Interior concrete slabs should be a minimum 5 inches thick. Reinforcement should consist of #3
bars placed at 18 inchts 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 vis~ueen 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 slmnp. The minimum steel recommended is not intended to prevent shrinkage
cracks.
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.
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
properly compacted f!jll soils or the dense terrace deposits as set forth in the 2013 California
Building Code, Table 1806.2. This value may be increased by 400 psf for each additional foot of
depth or width to a maximum value of 4,000 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 250 pounds per square foot pet' 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 1 /3 for wind and seismic loading.
SETTLEMENT
Settlement of compactied fill soils is normal and should be anticipated. Because of the type and
minor thickness of the fill soils anticipated under the proposed footings and the light building lpads,
total and differential settlement should be within acceptable limits.
PRESATURATION OF SLAB SUBGRADE
Due to the granular characteristics of the subgrade soils, presoaking of subgrade prior to co~crete
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 site
preparation and foundation excavation.
TEMPORARY SLOBES
For the excavation of foundations and utility trenches, temporary vertical cuts to a maximum height of
4 feet may be constructed in fill or natural soil. 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.
10
ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
TRENCH BACKFILL
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 back.fill 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. 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 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 and detailss 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; howe'[er, soil and geologic conditions can vary significantly between explotation
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.
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ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-J 106D5
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.
ADDITIONAL SERVICES
The review of plans anµ specifications, field observations and testing under our direction are integral
parts of the recommenc\ations 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 pot~ntial
claims that may arise during construction. Observation and testing are additional services, which are
provided by our firm, am.d should be budgeted within the cost of development.
Plates No. 1 through 3, Page L-1 and References are parts of this report.
12
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ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.17-1106D5
PLATENO.2
SUMMARY SHEET
BOREHOLE NO. 1
SOil.. DESCRIPTION
TOPSOIL
dark brown, moist, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, moist, medium dense, silty sand
becomes <ilense
bottom of borehole, no caving, no groundwater
borehole backfilled 2/16/17
y M
-----·-------------·--------------·-·--------·-------------------------------·-----------------·--------------------------·------------
DEPTH
Surface
1.0'
3.0'
4.0'
DEPTH
Surface
0.5'
2.0'
3.0'
4.0'
DEPTH
Surface
1.0'
3.0'
7.0'
BOREHOLE NO. 2
SOIL DESCRIPTION
TOPSOIL
dark brown, moist, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish bnown, moist, medium dense, silty sand
becomes dense
bottom of borehole, no caving, no groundwater
borehole backfilled 2/16/17
BOREHOLE NO. 3
SOIL DESCRIPTION
TOPSOIL
dark brown, moist, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish bli'own, moist, medium dense, silty sand
" u a "' "
becomes dense
bottom of borehole, no caving, no groundwater
borehole backfilled 2/16/17
BOREHOLE NO. 4
SOIL DESCRIPTION
TOPSOIL
dark brown, moist, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, moist, medium dense, silty sand
becomes, dense
bottom of borehole, no caving, no groundwater
borehole backfilled 2/16/17
y
114.7
y
101.8
y
------·----------·---·---------------------------------------------------------·-·-00 .................... -.... -------------------------------------· ...
Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN %
13
M
10.7
M
11.3
M
SOIL CLASSIFICATION CHART
COARSE
GRAINED
SOILS
MORl!ll<AN~ o, MATERIAL IS
LAAGERTHANNO.
200 SIM SIZE
FINE
GRAINED
SOILS
MORE~50'14
OF MIITERW. IS IMAU.ER THAN NO,
200 IIIEVI! SIZE
MAJOR DIVISIONS
GRAVEL
ANO
~AAVELLY
SOILS
SANO AND
SANDY
SOILS
MORETHAN'°" OFCOAASE l'fW:TION PASSING ON NO. 4 S!IM!
SILTS
ANO
CLAYS
SILTS
AND
CLAYS
CLEAN GRAVELS
(llTTL.E OR NO l'lNES)
CLEAN SANDS
SANDS WITH
FINES
(N'PRJ;CW!Lf AMOUNT
OF Jl'lNES)
UCUIOUMIT LESSTHAN50
LIQUID LIMIT
GREAT'ERT>Wl50
HIGh!L Y O~GANIC SOILS
SYMBOLS
GRAPH LETTER
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
CL
MH
CH
OH
PT
NOTE: C\W. SYMBOLS NU: USED TO INDICATE BORDERLINE SOIL CLASSIFICAilONS
CLASSmCATl01" I RANG.£ OF CRAlN SIZ£S
U.S. ST ANDARO CRAIN SIZE IN
SrEVESlZE MILLIMETERS
BOULDt;RS Above 12 lnchc:s Above 305
COBBL.£5 12 lnc:lu:s To 3 Inches J0S To 76.2
GRAVEL 3 Inches to No. 4 76 2 10 4 76
Coarse 3 Inches tO ¼ Inch 76.2 to 19 I
Fine ¼ Inch tO 'l\o. 4 19.1 to4.76
SANO No 4 to No. 200 06 tO 0.074
Coarse No. 4 t0 No 10 4 7610 2 00
Medium No. 10 to No. 40 2.00 tO 0.420
Fine No. 40 JO No. 200 0.420 t0 0.074
SILT AND CLAY Below No. 200 Below 0.074
GRAIN SIZE CHART
EAST COUNTY son. CONSULTATION
& ENOINEBR!NO , INC.
l 0925 HARTI.EY RD .. surra I, SANTEE. CA .92071
_(619) 258~?~1 Pu (619) 258-7902
TYPICAL
DESCRIPTIONS
WEJ..L-GRADEO GRAVE\.S, GRAV'El.-
SANO MIXTIJRES, LITTU OR NO FINES
POORLY-GRADED GRAViLS, GRAVEL•
SMC MOCI\JRES, unu OR NO FINES
SILTY GAAi/ELS, GRAVS.. SAND -SILT
MIXTURES
ClAYEY GAAi/ELS, GAAi/EL ·SANO•
CLAY MIXT\JR.ES
WE\.1.-GRADEl SANDS, ClAA\IE\.LY
SANDS, LITTll OR NO FINES
POORL Y4AA0£0 SANOS. GAAi/Ell Y
SANO. ume OR NO FINES
SIL TY SANOS, !Wj0 •SILT MIXTURES
Cl.AVEY SANOS, SANO· 0.AY
MIXTURiS
INORGANIC SILTS AND VERY FlPI!
SANDS, ROCK FLOUR, SIL TY OR
C\AYEY FINE IWIDI OR CI.AYEY SILTS
WITH Sl.lQliT PI.ASTlCITY
INORGANIC CV.YI OF LOW T0 MEDIUM
PLASTICITY, GltAVEll 'f C\AYS, SANOY
ClAYS, SIL TY CLAYS, U!AN CLAYS
ORGANIC SIL TS ANO ORGANIC SIL TY
CU. YS OF LOW PLASTICITY
INORGANIC SIL TS, MICACEOUI Oil
OIA l"OMACIOUll FINE SANO OR 81L TY SOILS
INORGANIC Cl.A YS OF HIGH P\.ASTICITT'
ORGANIC Ct.AYS OF MEDIUM TO HIGH
PLASTICITY, ORGANIC SILTS
PEAT, HUMUS. SWNJ.P SOILS WITtt
HIGH ORGANIC CONTENTS
,.
10 I· I I
I I V
V
I/
'"
I: •• w /
I/ /"'
" /i ;;
~v
~ 20 I/ I .,.,r 1 ww•°"'
\0 I
.Li ~~)1 w~~l I I I
e, 10 10 lC 40 50 10 70 IO
UQUIO UWIT (LL). E
PLASTICITY CHART
V
I
10 IC
l:'LA-% Ji/{,. 3
ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5
PAGEi.rt
LABORATORY TEST RESULTS
EXPANSION INDEX TEST (ASTM D4829)
IN1TIALDRY IN1TIAL
MOISTURE
CONTENT(%)
$ATURATED
MOISTURE
CONTENT(%)
DENSITY EXP ANSI ON
{PCF) INDEX LOCATION
9.3 16.9 111 .3 0 BH-1 @ 2.0·
PARTICLE SIZE ANALYSIS (ASTM D422)
' I
U.S. Standard Percent Passing Percent Passing
Sieve Size BH-1 @2.0' Bff..l @4.0'
Terrace Deoosits Terrace Deposits
1" --
1/2" --
3/8" --
#4 --
#8 --
#16 100 100
#30 90 90
#50 42 41
#100 22 19
#200 16 15
uses SM SM
14
ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.1 7-1106D5
REFERENCES
1. "2016 California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2",
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. "Maps of .Known Active Fault Near-Source Zones in California and Adjacent Portions ofNevc:ida to
be used with 1997 Uniform Building Code", Published by International Conference of Building
Officials.
5. "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.
6. "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.
7. "Foundations and Earth Structures, Design Manual 7.2", by Department of Navy Naval Facilities
Engineering Coqimand, May 1982, Revalidated by Change 1 September 1986.
8. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and l.M. Idriss, 1982.
15