HomeMy WebLinkAboutCDP 2017-0009; SCHIFF RESIDENCE; LIMITED GEOTECHNICAL INVESTIGATION; 2017-12-15Debra Schiff
EAST COUNTY SOIL CONSULTATION
AND ENGINEERING, INC.
10925 HARTLEY ROAD, SUITE "I"
SANTEE, CALIFORNIA 92071
(619) 258-7901
Fax 258-7902
1561 Whittier Avenue
Claremont, California 91711
Subject: Limited Geotechnical Investigation
Proposed Single-Family Residence
221 Normandy Lane
City of Carlsbad, California 92008
Dear Ms. Schiff:
pe, l -Olt.
\I 1,,'1 I (8
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December 15, 2017
Project No. l 7-l 106F6
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 building pad is underlain by an approximately 2-foot layer of
topsoil and dense terrace deposits to the explored depth of 6 feet. The development of the proposed
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,
JAN 16 2013
RECORD COPY
Initial Date
Debra Schifjl 22 I Normandy Lane Project No. I 7-1106D5
INTRODUCTION
This is to present the findings and conclusions of a limited geotechnical investigation for a
proposed single-family residence to be located at 221 Normandy Lane, 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 (3) 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 a near rectangular-shaped residential lot located on the east side of Normandy
Lane, in the City of Carlsbad, California. The property which encompasses an area of
approximately 3,280 square feet is occupied by a one-story, single-family residence. The site is
gently sloping to the west. Vegetation consisted of shrubs. The parcel is bordered by Normandy
Lane to the west and similar residential developments to the remaining directions.
The preliminary plans prepared by James A. Chinn, Architect of Del Mar, California indicate that
the proposed construction will include a single-family residence following demolition of the
existing one. It is our understanding that the structure will be three-story, wood-framed and
founded on continuous and/ or spread footings with a slab-on-grade floor.
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Debra Schiffl 221 Normandy lane Project No. 17-1106D5
FIELD INVESTIGATION AND LABORATORY TESTING
On November 29, 2017, three (3) boreholes were excavated to a maximum depth of approximately
6 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 (Qt1).
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 observed in the boreholes was approximately 2-foot
thick and consisted of dark brown, silty sand that was dry to moist, loose and porous in consistency
with some organics (rootlets).
Terrace Deposits (Oti}
Terrace deposits were underlying the topsoil layer. They generally consisted of reddish brown, silty
sand that was moist and medium dense to dense in consistency.
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Debra Schiff/ 221 Normandy Lane Project No. 17-1106D5
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 and 1.6 million years old.
Seismic Analysis
Based on our evaluation, the closest known "active" fault is the Newport-Inglewood Fault located
approximately 4.3 miles (6.9 kilometers) 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 7.25 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 stmctural
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 Newport-
Inglewood Fault Zone approximately 6.9 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 residence should be
designed in accordance with seismic design requirements of the 2016 California Building Code or
the Strnctural Engineers Association of California using the following seismic design parameters:
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Debra Sch{fjl 22 I Normandy Lane Project No. 17-1 !06D5
PARAMETER
Site Class
Mapped Spectral Acceleration For Short Periods,
Ss
Mapped Spectral Acceleration For a I-Second
Period, S1
Site Coefficient, Fa
Site Coefficient, Fv
Adjusted Max. Considered Earthquake Spectral
Response Acceleration for Short Periods, SMs
Adjusted Max. Considered Earthquake Spectral
Response Acceleration for I-Second Period, SM,
5 Percent Damped Design Spectral
Acceleration for Short Periods, Sos
5 Percent Damped Design Spectral
Acceleration for I-Second Period, S0 1
Geologic Hazard Assessment
Ground Rupture
Response
Response
VALUE 2016 CBC & ASCE 7 REFERENCES
D Table 20.3-l/ ASCE 7, Chapter 20
l.l74g Figure 1613.3.1(1)
0.451g Figure 1613.3.1(2)
1.030 Table 1613 .3 .3( I)
1.549 Table 1613.3.3(2)
1.210g Equation 16-3 7
0.698g Equation 16-38
0.806g 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 traces
within the vicinity of the project; however, this possibility cannot be completely rnled out. The
unlikely hazard of &rround 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 bedrock material, 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.
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).
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Debra Schiff/ 22 l Normandy Lane Project No. 17-1 I 06D5
GEOTECHNICAL EVALUATION
Based on our investigation and evaluation of the collected infonnation, we conclude that the proposed
development is feasible from a geotechnica] standpoint provided the recommendations herein will be
properly implemented during construction.
In order to provide a uniform 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 and/ or spread footings with reinforced slabs. Recommendations and
criteria 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 deposits,
which underlie the site. However, loose topsoil was encountered to a depth of approximately 2 feet
below surface grades. These soils are compressible. Due to the potential for soil compression upon
loading, remedial grading of these near-surface soils including overexcavation and recompaction will
be required unless footings are extended to the dense terrace deposits.
Following implementation of the earthwork 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 performed 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 43 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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Debra Schiff/ 221 Normandy lane Project No. 17-1106D5
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.
GRADING AND EARTHWORK
Based upon the proposed construction 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 Grubbing
The area to be graded or to receive fill and/or structure should be cleared of vegetation. 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 objects, which need to be rerouted or removed prior to
the inception ot: or during grading. All holes, 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 from our field and laboratory analysis indicates that loose topsoil covers the
building pad to a depth of approximately 2 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 the area, which is planned to
receive compacted fill and/or stnictural improvement. 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 optimum moisture content, and then
recompacted to a minimum of90 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 area 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
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*
Debra Schiff/ 221 Normandy lane Project No. 17-1106D5
extent of any overexcavation and recompaction should be evaluated in the field by a
representative of ECSC&E.
An alternative to the overexcavation and recompaction of subgrade is to extend footings for
the proposed structure to the dense terrace deposits.
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 during
the earthwork construction as required in the previous section.
Method and Criteria of 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 should be
moisture-conditioned within 2 percent over the optimum moisture content and compacted to at least
90 percent relative compaction per ASTM test method Dl557.
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
ensw-e that these soils are 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. Dw-ing construction, surface water should be controlled via berms, gravel/
sandbags, silt fences, straw wattles, siltation or bioretention basins, positive surface grades or other
method to avoid damage to the finish work or adjoining properties. All site entrances and exits must
have coarse gravel or steel shaker plates to minimize offsite sediment tracking. Best Management
Practices (BMPs) must be used to protect sto1m drains and minimize pollution. The contractor
should take measures to prevent erosion of graded areas until such time as permanent drainage and
erosion control measw-es have been installed. After completion of grading, all excavated surfaces
should exhibit positive drainage and eliminate areas where water might pond.
Standard Grading Guidelines
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.
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Debra Schifjl 221 Normandy Lane Project No. 17-1106D5
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 properly compacted fill soils or dense terrace
deposits. Continuous footings should be at least 18 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)
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 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.
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 fill soils or dense terrace deposits as set forth in the 2016 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 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 1/3 for wind and seismic loading.
SETTLEMENT
Settlement of compacted fill soils is normal and should be anticipated. Because of the type and
minor thickness of the fill soils anticipated under the proposed footings, total and differential
settlement should be within acceptable limits.
PRESATURA TION OF SLAB SUBGRADE
Due to the granular characteristics of the subgrade soils, presoaking of subgrade prior to concrete
pour is not required. However, subgrade soils in areas receiving concrete should be watered prior
10
Debra Schifjl 221 Normandy Lane Project No. 17-1106D5
to concrete placement to mitigate any drying shrinkage, which may occur following site
preparation and foundation excavation.
TEMPORARY SLOPES
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.
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 backfill should be uniformly watered and
compacted to a fhm 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 to finish-grade the site 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 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 details 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.
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Debra Schiff/ 221 Normandy Lane Project No. 17-1106D5
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.
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. I through 3, Page L-1 and References are parts of this report.
12
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EAST COUNTY SOIL CONSULTATION
& ENGINEERING, INC.
l 0925 HARTLEY RD .. SUITE I. SANTEE. CA 92071
(6 l 9) 2511-790 I Fax (619)258-7902
. .
(rJ(,#'ffil/V !Jj::-EX?J.oJ(47o)(:/ ,&~El/t1£.e.s,.
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ff--B,1?"9 sc.:wJ ff ?~e-c ;r
2.;i./ !Yt1;fM,9/VP/ )AWE
DEPTH
Surface
1.0'
2.0'
2.5'
6.0'
DEPTH
Surface
2.0'
4.0'
DEPTH
Surface
2.0'
4.0'
Debra Schiff/ 221 Normandy lane Project No. 17-J 106D5
PLATEN0.2
SUMMARY SHEET
BOREHOLE NO. 1
SOIL DESCRIPTION
TOPSOIL
dark brown, dry to moist, loose, porous, silty sand with rootlets ,, '' '' ,, ,, '' ,,
TERRACE DEPOSITS (Qt1)
reddish brown, dry to moist, medium dense to dense, silty sand
'' '' '' '' '' ,, ,,
bottom of borehole, no caving, no groundwater
borehole backfilled 11 /29/17
BOREHOLE NO. 2
SOlL DESCRIPTION
TOPSOIL
dark brown, moist, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt1)
reddish brown, moist, medium dense to dense, silty sand
bottom of borehole, no caving, no groundwater
borehole backfilled l 1 /29/ 17
BOREHOLE NO. 3
SOIL DESCRJPTION
TOPSOIL
dark brown, moist, loose, porous, silty sand with rootlets
TERRACE DEPOSITS (Qt1)
reddish brown, moist, medium dense to dense, silty sand
bottom of borehole, no caving, no groundwater
borehole backfilled I 1/29/17
y
y
117.J
y
Y = DRY DENSITY TN PCF M = MOISTURE CONTENT IN %
13
M
5.8
4.1
M
7.8
M
SOIL CLASSIFICATION CHART
COARSE
GRAINED
SOILS
MORE'!HAN50%
OF MATERIAL IS
LARGER THAN NO.
200 Sl!!V! SIZE
FINE
GRAINED
SOILS
MOREll-'ANl50%
OF MAlERIAI.IS SMAI.LER THAN NO.
2CO SIEVE SIZE
MAJOR DIVISIONS
GRAVEL
ANO
GRAVELLY
SOILS
MORE THAN SO%
OFCOAASE FRACTION
REl"AJNEO ON NO. 4
SlEVE
SANO
ANO
SANDY
SOILS
MORE THAN SC%
OF COARSE FRACTION PASSING
ON NO. 4 SIEVi
SILTS
AND
CLAYS
SILTS
ANO
CLAYS
CLEAN GRAVELS
(LITTLii OR NO F1NES)
GRAVELS WITH
FINES
(APPRECIA!!L!i AMOUNT
OF FINES)
SANDS WITH
FINES
[APPRECIABLE AMOUN" OF FlNES)
LIQUID LIMIT
LESSTKA!'I :Ki
Ll0UIO LIMIT
GREA~ER TKAN SO
HIGHLY ORGANIC SOILS
SYMBOLS
GRAPH LETTER
GW
GP
GM
GC
SM
SC
ML
CL
OL
MH
CH
OH
PT
TYPICAL
DESCRIPTIONS
W-::LL-GRADEC GRAVELS. GRAVEL.
SANO MIXTVRES, LITTL! OR NO f!NES
POORL Y-GAAOEO GRAVEL$, GRAVEL·
SANO MlXTURfS, ume OR NO FINES
SILTY GRAVELS, GRAVEL• SIINC • SILT Ml)CT"URES
CLAVEY GRAVELS, GRAVEL • SA.~D •
CLAY MIXTURES
WELL-GRADED SANOS, GRAVELLY
SANOS, LITTLI!. OR NO FINES
POORLY-GRACED SANOS, GRAVELLY
SA~D. LITT',E OR NO FINES
SILTY SANOS, SANO· SILT MIXT1JR.ES
CLAYEY SANOS, SANO • CLAY
MIXTURES
INORGANIC SILTS ANO VERY l'INE
SANOS, ROCK Fl.OUR, SIL TY OR
CLAYEY FINE SANOS OR CLAYEY SILTS
WITH SLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO MEDIUM
PLASTICITY, GAAi/ELL Y CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS
OR~NIC SIL TS AND ORGANIC Sil TY
Cl.A YS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS OR
CIA T01"ACEOUS FINE SANO OR SIL TY
SOILS
INORGANIC CLAYS OF HIClH PLASTICITY
ORGANIC CLAYS OF MEDIUM TO HIGH
PLASTICITY, ORGANIC SIL TS
PEAT, HUMUS, SWAMP SOILS WITH
HIGH ORGANIC CONTENTS
NOTE: DUAL SYM30LS AAE USEC TO INDICATE 80ROERLINE SOI~ ClASSIFICA~tONS
CLASSIFICA TlON RANGE OF CRAIN SIZES
U.S. STAl\'DARD I GRAIN SIZE IN
SIEVE SIZE i MILLIMETERS
BOULDERS /\bo•o 12 Inches Abo•• 305 COBBLES 12 Inches To) Inches ! 305 To 76.2
GRAVEL 3 Inches to No. 4 I 76.2 ro 4.76 Coar,c 3 Inches to ¼ Inch 76.2 to 19.1
Fine ¼ Inch to No. 4 : 19.I to 4.76
SAND No. 4 to No. 200 ' 4. 76 to 0.074
Come No. 4 to No. 10 I 4. 76 to 2.00 Medium No. 10 to No. 40 I 2.00 to 0.420
Fine No. 40 to No. 200 i 0.420 to 0.074
SILT AND CLAY Below No. 200 I Below 0.074
GRAIN SIZE CHART
EAST COUNTY SOIL CONSULTATION
& ENGINEERING, INC.
l 0925 HARTLEY RD .• surra I, SANTEE, CA .92071
_(619) 258·?~01 Fax (619) 258-7902
.. s $0 i ••l-+--1-+--Jf-'--t-+-ir-t--t~
t 30 i--l--!--~:..._1-+""7~+--,1--t--1
" ~ 20 i....-!----.l£--+-f-:;.4--''--t-.-:,-:.0t:-:"-1i--i
I
\0 ~~~~~~=t!=!~l.=! =!~
O tO to 30 ..0 SO 10 10 &O tO 100
U0Ui0 l.lW!f (U.), ,:
PLASTICITY CHART
MJZ !>£t· /5 ~V/ l
·11-1106r'1
INITIAL
MOISTURE
CONTENT(%)
9.0
l"
1/2"
3/8"
#4
#8
#16
#30
#50
#100
#200
uses
Debra Schiff/ 221 Normandy Lane Project No. 17-! 106D5
PAGE L-1
LABORATORY TEST RESULTS
EXP ANSI ON INDEX TEST (ASTM D4829)
INITIAL DRY SATURATED
MOISTURE
CONTENT(%)
DENSITY EXPANSION
(PCF) INDEX LOCATION
18.4 109.2 0
PARTICLE SIZE ANALYSIS (ASTM D422)
100
99
90
46
25
20
SM
14
BH-2 @3.5'
I . ~, ,
· Petcent 'Passing
: "Blt-i@ 3 .5'
' ' .. ,Terrace De sits . ~
100
92
47
26
20
SM
Debra Schiff/ 221 Normandy lane Project No. 17-1106D5
REFERENCES
I. "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. "Geotechn ical 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 of Nevada to
be used with 1997 Unifonn Building Code", Published by fntemational 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
Anny 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 Command, May 1982, Revalidated by Change I September 1986.
8. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and I.M. Idriss, 1982.
9. "Geology of San Diego Metropolitan Area, California", Bulletin 200, by Michael P. Kennedy and
Gary L. Peterson, 1975.
15