HomeMy WebLinkAboutCDP 2017-0026; MCDOWELL ADDITION; LIMITED GEOTECHNICAL INVESTIGATION PROPOSED RESIDENTIAL ADDITIONS; 2016-06-24EAST COUNTY SOIL CONSULTATION
AND ENGINEERING, INC.
10925 HARTLEY ROAD, SUITE "I"
SANTEE, CALIFORNIA 92071
(619) 258-7901
Fax 258-7902
David & Anna McDowell
4050 Skyline Road
Carlsbad, California 92008
Subject: Limited Geotechnical Investigation
Proposed Residential Additions
4050 Skyline Road
Carlsbad, California 92008
Dear Mr. & Mrs. McDowell:
June 24, 2016
Project No. 16-1 l06H6
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 improvement.
Our investigation has found that the area of the proposed improvement is underlain by
undocumented fill and topsoil to a maximum depth of approximately 3 feet below existing grade.
These soils were underlain by dense terrace deposits to the explored depth of 6 feet. It is our
opinion that the construction of the proposed residential additions 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.
DAVID & ANNA McDOWEW 4050 SKYUNE ROAD PROJECT NO. 16-l 106H6
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
2013 CBC Seismic Design Criteria ...................................................................................................... 6
Geologic Hazard Assessment. ............................................................................................................... 6
GEOTECfiNICAL EVALUATION .................................................................................................................. 7
Compressible Soils ................................................................................................................................ 7
Expansive Soils ...................................................................................................................................... 7
Groundwater .......................................................................................................................................... 7
CONCLUSIONS AND RECOMMEND A TIO NS ............................................................................................ 7
CLEARING AND GRUBBING ......................................................................................................................... 8
FOUNDATIONS ................................................................................................................................................ 8
SETTLEMENT ................................................................................................................................................... 8
PRESATURATION OF SLAB SUBGRADE ................................................................................................... 8
TEMPORARY SLOPES .................................................................................................................................... 9
TRENCH BACKFILL ........................................................................................................................................ 9
DRAINAGE ........................................................................................................................................................ 9
FOUNDATION PLAN REVIEW ...................................................................................................................... 9
LIMITATIONS OF INVESTIGATION ........................................................................................................... 9
ADDITIONAL SERVICES ............................................................................................................................ 10
PLATES
Plate I-Location of Exploratory Boreholes
Plate 2 -Summary Sheet (Exploratory Borehole Logs)
Plate 3 -USCS Soil Classification Chart
PAGE L-1, LABORATORY TEST RESULTS .............................................................................................. 12
REFERENCES ................................................................................................................................................. 13
2
DAVID&ANNA McDOWELU4050SKYUNEROADPROJECTNO.16-J/06H6
INTRODUCTION
This is to present the findings and conclusions of a limited geotechnical investigation for the
proposed second story and two-story additions to the northwest portion of the existing single-
family residence located at 4050 Skyline Road, in the City of Carlsbad, California.
The objectives of the investigation were to evaluate the existing soils conditions and provide
recommendations for the proposed improvement.
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 improvement. 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 improvement
SITE DESCRIPTION AND PROPOSED CONSTRUCTION
The subject site is an irregular-shaped residential lot located on the east side of Skyline Road, in the
City of Carlsbad, California. The property, which encompasses an area of approximately 27,250
square feet includes a one-story house \\-ith a basement garage. The site slopes moderately to the
west. Vegetation consisted of grass, shrub and trees. Site boundaries include Skyline Road to the
west and similar residential developments to the remaining directions.
The site plan prepared by Wright Design of Carlsbad, California indicate that the proposed
improvement will include a second story and a two-story additions to the northwest portion of the
existing single-family residence. It is our understanding that the two-story addition will be wood-
framed and founded on continuous footings with a raised-wood floor.
3
DAVID & ANNA McDOWEW 4050 SKYUNE ROAD PROJECT NO. 16-110686
FIELD INVESTIGATION AND LABORATORY TESTING
On May 18, 2016, 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 Sheet11• The soils were visually and texturally classified according to the filed
identification procedures set forth on Plate No. 3 entitled "USCS Soil Classification".
Folio-wing the field exp]oratio~ 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.
Undocumented Fill
Undocumented fill soils were encountered in the boreholes to a depth of approximately 2 feet below
existing grade. They consisted of dark to light brown, silty sand that was moist and loose in
consistency.
Topsoil
Topsoil is the surficial soil material that mantles the ground, usually containing roots and other organic
materials, which supports vegetation. Topsoil was observed below the undocumented fill 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).
4
DAVID & ANNA McDOWELi./ 4050 SKYUNE ROAD PROJECT NO. J 6-l 106H6
Terrace Deposits (Qt)
Terrace deposits were encountered below the topsoil. They generally consisted of reddish bro~ silty
sand that was moist and medium dense to dense in consistency.
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 1.6 million years old.
Seismic Analysis
Based on our evaluation, the closest known "active" fault is the Rose Canyon Fault located
approximately 9.4 kilometers (5.9 miles) to the west. The Rose Canyon 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 from 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 0.43g. 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 0.28g.
5
DAVID & ANNA McDOWELU 4050 SKYLINE ROAD PROJECT NO. 16-1106H6
2013 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 9.4 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 additions
should be designed in accordance with seismic design requirements of the 2013 California Building
Code or the Structural Engineers Association of California using the following seismic design
parameters:
PARAMETER ..
Site Class
Mapped Spectral Acceleration For Short Periods,
Ss
Mapped Spectral Acceleration for a I-Second
Period, St
Site Coefficient, Fa
Site Coefficient, F v
Adjusted 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, Sot
Geologic Hazard Assessment
Ground Rupture
Response
VALUE 2013 CBC & ASCE 7 REFERENCES
D Table 20.3-1/ ASCE 7, Chapter 20
l.l 11.g Figure 16 I 3.3.1(1)
0.427g Figure 1613.3.1(2)
1.056 Table 1613.3.3(1)
1.573 Table 1613.3.3(2)
1.173g Equation 16-37
0.672g Equation 16-3 8
0.782g Equation 16-39
0.448g Equation 16-40
Ground rupture due to active faulting is not considered likely due to the absence ofknovvn 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
Th.ere 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 improvement or
adjacent properties.
6
DAVID & ANNA McDOWELV 4050 SKYLINE ROAD PROJECT NO. J 6-1106H6
Tsunamis and Seiches
The site is not subject to inundation by tsunamis due to its elevation and distance to the ocean. 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
construction of the proposed additions is feasible from a geotechnical standpoint provided the
recommendations herein will be properly implemented during construction.
In order to provide a uniform support for the proposed additions, footings should be embedded into the
dense terrace deposits. The foundations may consist of reinforced continuous or spread footings with
reinforced slabs. Recommendations and criteria for foundation design are provided in the Foundations
and Slabs recommendations section of this report.
Compressible Soils
Our field observations and testing indicate low compressibility within the terrace deposits, which
underlie the area of the proposed improvement. However, loose undocumented fill and topsoil were
encountered to a depth of approximately 2 to 3 feet below surface grades. These soils are
compressible, therefore not adequate for the support of the proposed additions.
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 representative sample of the terrace deposits to
determine volumetric change characteristics \.Vith 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 of approximately 100 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
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
7
DAVID & ANNA McDOWELV 4050 SKYLINE ROAD PROJECT NO. 16-1106H6
is suitable for the proposed residential additions provided the recommendations set forth are
implemented during construction.
CLEARING AND GRUBBING
The area of the proposed improvement should be cleared of vegetation. 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.
FOUNDATIONS
a. Continuous and spread footings are suitable for use and should extend to a minimum depth of 18
inches below the lowest adjacent grade into the dense terrace deposits for the proposed second
story and two-story additions. 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 18 inches. Their reinforcement should consist of a minimum of #4 bars spaced
12 inches on center (each way) and placed horizontally near the bottom. New footings should be
dowelled to existing footings in accordance with the structural engineer requirements. The
minimum reinforcement recommended is based on soil characteristics and is not intended to
supersede the structural engineer requirements.
b. 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 as set forth in the 2013 California Building Code, Table 1804.2. 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.
c. 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
Since the proposed footings are anticipated to be supported by the dense terrace deposits, the total and
differential settlement should be within tolerable limits.
PRESATURATION OF SLAB SUBGRADE
Because of the granular characteristics of on-site soils, presoak.ing 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.
8
DAVID & ANNA McDOWELL/ 4050 SKYLINE ROAD PROJECT NO. 16-1106H6
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 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 additions 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. In earth areas, a minimum gradient of 5 percent away from the structure for a
distance of at least IO feet should be provided. 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 finn should review the foundation plans during the design phase to assure confonnance 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.
9
DAVID & ANNA McDOWELL/ 4050 SKYLINE ROAD PROJECT NO. 16-1106H6
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 cany 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.
10
.y.·~.:·.
~,_, !!•:
-·-· -----,
EAST COUNTY son.. CONSULTATION
& ENGINEERING, INC.
I 092.S HARTI.EY RD .. SUITE I. SANTEE, CA .92071
(619) 258-7901 Fax (619) 258-7902
f ·~,,,;c
r, .. ;,,--.-~ .. i
,'. ~ ' Ja.c, I .· f
• ! ,r•lt>" ..
I
I ;..~ I
J,&G (#/VG Pf; ;U)/6
?M-7£ !VO, /
DEPTH
Surface
1.0'
2.0'
3.0'
6.0'
DEPTH
Surface
2.0·
3.0'
5.0'
DEPTH
Surface
OS
1.5'
4.0'
DAVID & ANlvA McDOWEW 4050 SKYLINE ROAD PROJECT NO. 16-1 J06H6
PLATEN0.2
SUMMARY SHEET
BOREHOLE NO. 1
SOIL DESCRIPTION
UNDOCUMENTED FILL (Qut)
dark brown. moist, loose, silty sand with rootlets
light brown, moist, loose, silty sand
TOPSOIL
dark brown, moist, loose, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown., moist. medium dense, silty sand
bottom of borehole, no caving. no groundwater
borehole backfilled 5/18/16
BOREHOLE NO. 2
SOIL DESCRIPTION
UNDOCUMENTED FILL (Qut)
light brown, moist, loose, silty sand
TOPSOIL
dark brown, moist, loose, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, moist, medium dense, silty sand
bottom of borehole, no caving, no groundwater
borehole backfilled 5/I 8/16
BOREHOLE NO. 3
SOIL DESCRIPTION
UNDOCUMENTED FILL (Qut)
light brovm. moist, loose, silty sand
TOPSOIL
dark brown, moist, loose, silty sand with rootlets
TERRACE DEPOSITS (Qt)
reddish brown, moist, medium dense, silty sand
bottom of borehole, no caving. no groundwater
borehole backfilled 5/18/16
y
104.0
117.0
y
y
-------------------·----·----------·-----
Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN%
11
M
8.8
11.9
M
M
MAJOR DIVISIONS SYMBOL DESCRIPTION
GW WEU. GRADED ORA VELS OR ORA VEL--SAND
MIXTURES. t.rrn..E OR NO FINES
GRAVELS GP POORLY GRADED ORA VELS OR GRA VEL·SAND (MORETHAN½
OFCOARSE MtxTURES, LITTLE OR NO FINES
FRACTION GM SILTY GRAVELS, GRAVEL.SAND-SILT MIXTURES >N0.4SIEVE
SIZE) COARSE GC
GRAINED SOILS CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES
(MORE THAN ½ OF SOIL SW > NO. 200 SIEVE SIZE) WELL O.RADED SANDS OR ORA VELL Y SANDS,
UTILE OR NO FINES
SANDS SP POORLY GRADED SANDS OR GRA YELL Y SANDS. (MORE THAN½
OFCOARSE UTILE OR NO FINES
FRACTION SM SILTY SANDS, SILT-SAND MIXTURES <N0.4SJEVE
SIZE)
SC Cl.A YEY SANDS, SAND-CLAY MIXI1.JRES
ML INORGANIC SIL TS AND VERY FINE SANDS, ROCK
SILTS& FLOUR. SILTY OR CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
CLAYS CL INORGANIC CLAYS OF LOW TO MEDJUM
L!QUIDUMJT PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS.
<SO SILTY CLAYS, LEAN CLAYS
FINE GRAINED OL
SOILS ORGANIC SILTS AND ORGANIC SILTY CLAYS OF
LOW PLASTICITY
(MORE THAN ½ OF SOIL MH < NO. 200 SIEVE SIZE) INORGANIC SILTS, MICACEOUS ORDIATOMACEOUS SILTS& FD-leSANDYORSILTYSOll.S,ELASTICSILTS
CLAYS CH INORGANIC CLAYS OF HIGH PLASTICITY, FAT LIQUID LIMIT
>SO CLAYS
OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,
ORGANIC SILTY CLAYS ORGANIC SIL TS
ffiGHL Y ORG~1C SOILS Pt PEAT AND OTHER HJGHL Y ORGANIC SOILS
CLASSIFICATION CHART (UNIFIED SOIL CLASSIFICATION SYSTEM)
CLASSMCATION RANGE OF GRAIN SIZES
U.S. STANDARD GRAIN SIZE IN
SIEVE SIZE MILLIMETERS
BOULDERS Above 12 Inches Above30S
COBBLES 12 Inches To 3 Inches 30STo 76.2
GRAVEL 3 Inches to No. 4 76.2 to 4.76
Coarse 3 Inches to ¾ Inch 76.2 to 19.1
Fine ¾ Inch to No. 4 19.l to 4.76
SAND No. 4 to No. 200 4.76 to 0.074
Coarse No. 4 to No. 10 4.76 tol.00
Medium No. 10 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 Below0,074
GRAIN SIZE CHART
EAST COUNTY SOIL CONSULTATION
AND ENGINEERING, INC.
10925 HARTLEY ROAD, SUITE "I"
SANTEE, CALIFORNIA 92071
U.S.C.S. SOIL CLASSIFICATION
..
\,.tOUIO-\.UUT l\,l,J ~*,...... ...
PLASTICITY CHART
PN1t> I #IN/I Mc.Doweu.-
#PJ€3:or' Nt)-lt-Jtt96f/t
f>t-4-Jc. NCJ~ 3
i/tl/'rE z+ 1 $0/b
fNITIAL
MOISTURE
CONTENT{%)
8.3
1"
1/2"
3/8"
#4
#8
#16
#30
#50
#100
#200
uses
DAVID &ANNA McDOWELV 4050 SKYLINE ROAD PROJECT NO. 16-1106H6
PAGE L-1
LABORATORY TEST RESULTS
EXP ANSI ON INDEX TEST (ASTM D4829)
SATURATED
MOISTURE
CONTENT(%)
16.8
INITIAL DRY
DENSITY EXPANSION
(PCF) fNDEX
115.7 0
PARTICLE SIZE ANALYSIS (ASTM D422)
100 100
92 93
50 53
26 25
18 17
SM SM
12
LOCATION
BH-1 @ 1.5'
100
91
50
27
22
SM
DAVID & ANNA McDOWELU 4050 SKYLINE ROAD PROJECT NO. 16-J 106H6
REFERENCES
1. "2013 California Building Code, California Code of Regulations, Tide 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. "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 Unifonn 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
Anny Corps of Engineers, No. T', 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 I September 1986.
9. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and I.M. Idriss, 1982.
13