HomeMy WebLinkAboutCDP 2018-0019; SNYDER RESIDENCE; GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE; 2018-03-01James M. Snyder
10612 Prospect A venue
Santee, California 92071
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
1781 Skimmer Court
Carlsbad, California 92011
Dear Mr. Snyder:
March 1, 2018
Project No. l 8-l l 27E5
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 proposed building pad is underlain by undocumented fill soils to a
maximum depth of approximately 3 feet below existing grade. Dense sandstone of the Santiago
Formation was encountered below the fill soils to the explored depth of 6 feet. It is our opinion
that the development of the proposed single-family residence is geotechnically feasible provided
the recommendations herein are implemented in the design and construction.
Should you have any questions with regard to the contents of this report, please do not hesitate to
contact our office.
Respectfully submitted,
Mamadou Saliou Diallo, P .E.
RCE 54071, GE 2704
MSD/md
James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1127E5
TABLE OF CONTENTS
INTRODUCTION .............................................................................................................................................. 3
SCOPE OF SERVICES ...................................................................................................................................... 3
SITE DESCRIPTION AND PROPOSED CONSTRUCTION ........................................................................ 3
FIELD INVESTIGATION AND LABO RA TORY TESTING ........... .' ........................................................... .4
GEOLOGY ......................................................................................................................................................... 4
Geologic Setting .................................................................................................................................... 4
Site Stratigraphy .................................................................................................................................... 4
SEISMICITY ...................................................................................................................................................... 5
Regional Seismicity ............................................................................................................................... 5
Seismic Analysis ................................................................................................................................... 5
2016 CBC Seismic Design Criteria ...................................................................................................... S
Geologic Hazard Assessment. ............................................................................................................... 6
GEOTECllNICAL EVALUATION .................................................................................................................. 7
Compressible Soils ................................................................................................................................ 7
Expansive Soils ...................................................................................................................................... 7
Groundwater .......................................................................................................................................... 7
CONCLUSIONS AND RECOMMENDATIONS ............................................................................................ 7
GRADING AND EARTHWORK ...................................................................................................................... &
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 SLABS ........................................................................................................................ 9
SETTLEMENT ................................................................................................................................................. 10
PRESA TURA TION OF SLAB SUBGRADE ................................................................................................. 10
TEMPORARY SLOPES .................................................................................................................................. 11
TRENCH BACKFILL ...................................................................................................................................... 11
DRAINAGE ...................................................................................................................................................... 11
FOlJNDATION.PLAN REVIEW .................................................................................................................... 11
LIMITATIONS OF INVESTIGATION ......................................................................................................... 12
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 ................................................................................................................................................. 1 S
2
James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1 /27E5
INTRODUCTION
This is to present the findings and conclusions of a limited geotechnical investigation for a
proposed two-story, single-family residence to be located at 1781 Skimmer Court, in 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 ofrepresentative soil samples at selected depths. The obtained samples were sealed
in moisture-resistant containers and transported to the laboratory for subsequent analysis.
0 Laboratory testing of samples representative of the types of soils encountered during the field
investigation
0 Geologic and engineering analysis of the field and laboratory data, which provided the basis
for our conclusions and recommendations
0 Production of this report, which summarizes the results of the above analysis and presents our
findings and recommendations for the proposed development
SITE DESCRIPTION AND PROPOSED CONSTRUCTION
The subject site is a rectangular-shaped residential lot located on the east side of Skimmer Court, in
City of Carlsbad, California. The property which encompasses an area of 47,850 square feet (435'
x 110') was occupied by a single-family residence with a detached garage. We understand that the
residence was burned down leaving the garage and the concrete foundation and slab. The building
pad is relatively level with moderate slopes to the east. Vegetation consisted of grass, shrub and
trees. The parcel is bordered by Skimmer Court to the west, a similar residential development to
the south and vacant properties to the remaining directions.
The preliminary plans prepared by Roy Johnson, Architect of La Mesa, California indicate that the
proposed construction will include a new single-family residence following removal of the
remaining foundation and slab. The structure will be two-story, wood-framed and founded on
continuous and spread footings with a slab-on-grade floor.
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James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1 /27E5
FIELD INVESTIGATION AND LABORATORY TESTING
On February 13, 2018, 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, maximum dry density and optimum moisture content, 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 sandstone/ claystone of the Santiago Formation (Tsa).
Site Stratimphy
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 (QuO
Undocumented fill soils were encountered in the boreholes to depths ranging from approximately 6
inches to 3 feet below existing grade. They consisted of light brown sand with silt that was dry to
moist and loose in consistency.
Santiago Formation (Tsa}
Sandstone of the Santiago Formation was encountered below the fill soils. The material generally
consisted oflight gray, silty sand that was dry to moist and dense in consistency.
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James M Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1127E5
SEISMICITY
Regional Seismicity
Generally, Seismicity within California can be attributed to the regional tectonic movement talcing
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 6 miles (10 kilometers) 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 SO-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 0.41g. 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 0.27g.
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 10 km to the west. Ground shaking from this fault or one of the major
active faults in the region is the most likely happening to affect the site. With respect to this
hazard, the site is comparable to others in the general area. The proposed residential structure
should be designed in accordance with seismic design requirements of the 2016 California Building
5
James M Snyder/ 1781 Skimmer CourJ/ Carlsbad Project No. 18-1127E5
Code or the Structural Engineers Association of California using the following seismic design
parameters:
',PA.RXN$tER',·r:,:/;1>.::.)J ;:;:_;-:,·: ___ ·,, :.' '!': ' : :\,\';);;;:, t'.Y.'AlfUE\ ::zo16:(:J.Q(J'i)\:SCE}7.':U~N~P.:::'._-.i
Site Class
Mapped Spectral Acceleration For Short Periods,
Ss
Mapped Spectral Acceleration For a 1-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 1-Second Period, SMt
5 Percent Damped Design Spectral Response
Acceleration for Short Periods, Sos
S Percent Damped Design Spectral Response
Acceleration for I -Second Period, S01
Geologic Hazard Assessment
Ground Rupture
D Table 20.3-1/ ASCE 7, Chapter20
1.068g Figure 1613.3.1(1)
0.413g Figure 1613.3.1(2)
1.073 Table 1613.3.3(1)
1.587 Table 1613.3.3(2)
1.146g Equation 16-37
0.655g Equation 16-38
0.764g Equation 16-39
0.437g Equation 16-40
Ground rupture due to active faulting is not considered likely due to the absence oflmown 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 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 inwidation 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).
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James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-I J27E5
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 uniform support for the proposed structure, footings should be embedded into
properly compacted fill soils or the dense sandstone of the Santiago Formation. The foundations may
consist of reinforced continuous and/ or spread footings with reinforced slabs. Recommendations and
criteria for foundation design are provided in the Foundation and Slab recommendations section of this
report.
Compressible Soils
Our field observations and testing indicate low compressibility within the dense sandstone of the
Santiago Formation, which underlies the site. However, loose undocumented fill was encountered to a
maximum depth of approximately 3 feet below surface grades. These soils are compressible. Due to
the potential for soil compression upon loading, remedial grading of these loose soils, including
overexcavation and recompaction will be required unless footings are extended to the dense sandstone
of the Santiago Formation.
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 fill soils to determine
volumetric change characteristics with change in moisture content. An expansion index of 9 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 300 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 is
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James M Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1127E5
suitable for the proposed residential development provided the recommendations set forth are
implemented during construction.
GRADING AND EARTHWORK
Based upon the preliminary plans and the information obtained during the field investigation, we
anticipate that the proposed residence will be founded on continuous and/ or spread 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 dwing 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 and concrete
waste from the demolition of the remaining foundation and slab. 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 of, 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
Infonnation obtained from our field and laboratory analysis indicates that loose, undocumented fill
soils cover the building pad to a maximum 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 undocumented fill and other loose natural soils should be removed from the area, which is
planned to receive compacted fill and/or structural 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 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 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
extent of any overexcavation and recompaction should be evaluated in the field by a
representative of ECSC&E.
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James M. Snyder/ 1781 Skimmer Court/Carlsbad Project No. /8-1127E5
Transitions Between Cut and Fill
The proposed structure is anticipated to be founded in properly compacted fill soils or dense sandstone
of the Santiago Fonnation. 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 optimwn 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 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. During construction, surface water should be controlled via benns, 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 storm drains and minimize pollution. The contractor
should take measures to prevent erosion of graded areas until such time as permanent drainage and
erosion control measures 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 geotecbnical report differs from
the Standard Grading Guidelines, the requirements outlined in the report shall govern.
FOUNDATIONS AND SLABS
a. Continuous and spread footings are suitable for use and should extend to a minimum depth of 18
inches for the proposed two-story structure into the properly compacted fill soils or dense sandstone
of the Santiago Formation. 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 minimwn of #4 bars spaced 12 ~ches
9
James M Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1127 ES
on center (each way) and placed horizontally near the bottom. These recommendations are based
on geoteclmical considerations and are not intended to supersede the structural engineer
requirements.
b. Interior concrete slabs-on-grade should be a minimum 4 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
the properly compacted fill soils or dense sandstone of the Santiago Formation 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 and the light building loads,
total and differential settlement should be within tolerable limits.
PRESATURATION 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
to concrete placement to mitigat~ any drying shrinkage, which may occur following site
preparation and foundation excavation.
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James M Snyder/ 1781 Skimmer Court/Carlsbad Project No.18-1127E5
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 BACK.FILL
Excavations for utility lines, which extend under structural areas should be properly backfilled and
compacted. Utilities should be bedded and backfilled with clean sand or approved granular soil to
a depth of at least one foot over the pipe. This backfill should be uniformly watered and
compacted to a firm condition for pipe support. The remainder of the backfill should be on-site
soils or non-expansive imported soils, which should be placed in thin lifts, moisture-conditioned
and compacted to at least 90% relative compaction.
DRAINAGE
Adequate measures should be undertaken after the structure and other improvements are in place,
such that the drainage water within the site and adjacent properties is directed away from the
foundations, footings, floor slabs and the tops of slopes via rain gutters, downspouts, surface swales
and subsurface drains towards the natural drainage for this area. A minimum gradient of 2 percent
is recommended in hardscape areas adjacent to the structure. In earth areas, a minimum gradient of
S 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 widennining 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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James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1 /27E5
LIMITATIONS OF INVESTIGATION
Our investigation was performed using the skill and degree of care ordinarily exercised, under similar
circwnstances, 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.
Th.is 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. 1 through 3, Page L-1 and References are parts of this report.
12
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EAST COUNTY SOIL CONSUL. TA TION
& ENOINEERINO, INC.
10925 HARn..EY RD •• SUITS J, SAN'TEE. CA 9207 I
(619) lSB-7901
,sr,
I
DEPTH
Surface
0.5'
1.0'
3.01
DEPTH
Surface
1.5'
6.0'
DEPTH
Surface
1.0'
3.0'
6.01
James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-l 127E5
PLATEN0.2
SUMMARY SHEET
BOREHOLE NO. 1
SOIL DESCRIPTION
UNDOCUMENTED FILL (Quf)
light brown, moist, loose, sand with silt
SANTIAGO FORMATION (Tsa)
light gray, dry to moist, medium dense to dense, silty sand
« " " " " «
bottom of borehole, no caving, no groundwater
borehole backfilled 2/13/18
BOREHOLE NO. l
SOIL DESCRIPTION
UNDOCUMENTED FILL (Quf)
light brown, dry to moist, loose, sand with silt
SANTIAGO FORMATION (Tsa)
light gray, moist, medium dense to dense, silty sand
bottom of borehole, no caving, no groundwater
borehole backfilled 2/13/18
BOREHOLE NO. 3
SOIL DESCRIPTION
UNDOCUMENTED FILL (Qut)
light brown, dry to moist, loose, sand with silt
« " " " "
SANTIAGO FORMATION (Tsa)
light gray, moist, medium dense to dense, silty sand
bottom of borehole, no caving, no groundwater
borehole backfilled 2/13/18
y
108.7
y
y
88.1
_________________ , _________________________ _
Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN %
13
M
12.5
M
M
9.8
SOIL CLASSIFICATio'rlc"HART
COAASI!
GRAINIID
SOILS
MORll'IWAN-OFW.T&RW.18 WGIR THAN NO.
200Sl!Vl!8tZe
FINE GRAINED
SOILS
MORITHANIIOI'
Of' PMT&AIAl.111 IMALI.ER THAN NO,
2C0811\11!SID!
MAJOR DIVISIONS
GRAVEL AND
GRAVELLY
SOILS
CLEAN GRAVELS
11,ITTl.ll OR NO PINIIII)
GRAVELS WITH
~:::.,_• FINES
FRAGTION RITAINID ON NO. 4 81M !APPR£CIAIILI! AMOUNT
SANO AND
SANDY sou
MORITMNlllll Ol'CCIARR l'IWfflON l'AIIIINQ ON NO. 4115111
SILTS
AND
CLAYS
SILTS
ANO
CLAYS
O,PMfl)
CLE'ANSANOS
(l.ITTl.li OR NO FIN!I)
SANOS WITH
FINES
(Al'JIRICNLI AMOUNr
01 PIHU)
UQUIDUMIT LIIITMANIO
LWD~!Mlf
OIWATl!R THAN IO
HIGHLY OllaANIC SOILS
SYMBOLS
LETTER
GW
GP
GM
oc
SW
SP
SM
SC
ML
CL
CL
MH
CH
OH
PT
TYPICAL
DESCRIPTIONS
WEl.l-GIWIIIO QRAVIIJI, GRAVEL· SAND MIX'IURt8, LmL! OR NO FIN&8
POOIII.Y-GIW)Bg OMV&UI, GAAll&I. • SAND MllrnJRES. LITI\.E OR NO PINES
811.TV ORA'IIE.8, IIAAVll. • MND • ILT MDCl'Ulllill
Cl.AVEY GRAYEUI. GRAVEL• IANO • CIAV MDCTUAE4
WEU,GRADED SANOS, GRAVEi.LY IANllS, I.Im.I OR NO PINIS
P00RLY-GJW>ID8AND8. OAAVELLY
SAND, LITl'U! OR NOl'IN&8
811.'l"(IWIDI, 111\ND•SllTMtXIURIII
ClAYEY IWIDII, SAND• CI.AY
MOC'I\IMI
INORGANIC IILTI ANO~ PIHi BANDS, ROCKA.OUII, IILTY OA
OIAffl FUii &ANDS OR ClAYIYSILTI WITH IUCIMT PLASltCITY
INORGNIIC CIAYI OI' L0W T0 M1IDIUM PU\IITIOITY,GIIAVILLY CLAYS.8/IHOY CIAVS. IIL TY ClAYI, ~ OI.A't'a
ORQAMCIILYIANDOIIOANICILTY
CLA~DFLOWPlMTICITY
INORGANIC ll~TII. ~801/8 OR DIAlCIW:l!OU8 l'IN! INID OR IJL TY
SOILS
INORCWIIC CIAYIOFHIGH PI.AlnCITY
Ol'ICIN«O CUIYI OF MSDIIIM TO IIIGH PI.ASTIDl1'f, ORGNIIC81.T8
PEAT, HUMUl, IWAMl"IOll.8Wlnt HICIH 0RGAN1C CONT!IIT8
NOT!: DUM. SYMIDUI Ml USED lO INDICATE 80ROERLINI SOI\. ClAS8111CATIONS
CLASSJIIICATION RANGE OF GRAIN Sl:,,u
U.S, STANDARD GRAJN SIZE IN
SIEVESIU MILIIMffERS
BOULDERS Above 12 lnoha Abova30S
COBBLU 12 lnohea TO 3 Inches 3oSTo 76.2
GRAVEL 3 llloha to No. 4 76.2 I0-4.76
C°""'o 3 lnohoa 10 ¼ lnoh 76.2 to 19.1
Fine ~ Inell to No. 4 19.1 to4.76
SAND No, 4 to No. 200 4. 76 IO 0.074
Coe,sc No. 4 to No, 10 4.76102.00
Medium No. IO 10 No. 40 2.0010 0,420
fh1t No. 40 to No.100 0.420 to 0.074
SILT AND CLA V Below No, 200 Below0.074
GRAIN SIZE CHART
EAST COUNTY SOIL CONSULTATION
& BNOINSBRINO, INC.
10925 HAR1U!Y RO .. SUITE 1, SANTBB. CA ,9207 I
_(619) 258~?!()1 PM C619) 258-7~
• ,o
/ IO / ,./
/ °" ./ I,"
V i./
1/ C\. vl
/ _/ ~ i ll!Wrllt
II -M~ 0 a II u • .a so ao ,o III to ,ao
UOUII u11r lu.). ll
PLASTICITY CHART
✓~ 14. ~$mf lm)B:r
/7/J/ 517A'J~ &?ti/tr
James M Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1127E5
PAGEL-1
LABORATORY TEST RESULTS
MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557)
The maximum dry densities and optimum moisture contents of the fill materials as determined by ASTM
D1557, Procedures A and B which use 25 blows of a 10 pound slide hammer falling from a height of 18
inches on each of S equal layers in a 4 inch diameter 1/30 cubic foot compaction cylinder and Procedure C
which uses 56 blows of a 10 pound slide hammer falling from a height of 18 inches on each of 5 equal
layers in a 6 inch diameter 1/13.3 cubic foot compaction cylinder are presented as follows:
SOIL TYPE/
PROCEDURE
INITIAL
MOISTURE
CONTENT{%)
12.3
l"
1/2"
3/8"
#4
#8
#16
#30
#50
#100
#200
uses
MAXIMUM
DRY DENSITY
DESCRIPTION [PCF)
LIGHT BROWN SILTY SAND 115.0
EXPANSION INDEX TEST (ASTM D4829)
INITIAL DRY
OPTIMUM
MOISTURE
CONTENT
(%)
12.0
SATURATED
MOISTURE
CONTENT(%)
DENSITY EXPANSION
(PCF) INDEX
22.3 102.2 9
PARTICLE SIZE ANALYSIS (ASTM D422)
----
N -
100 -
99 100
96 99
90 94
61 56
20 28
9 19
SP-SM SM
14
LOCATION
BH-3@1.5'
LOCATION
BH-3@1.5'
James M. Snyder/ 1781 Skimmer Court/ Carlsbad Project No. 18-1127E5
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. "Concrete Engineering of Streets and Local Roads", Reference Manual, by the American Concrete
Association (acpa), Updated December 2000.
4. "Geotechnical and Foundation Engineering: Design and Construction", by Robert W. Day, 1999.
S. "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
Army Corps of Engineers, No. 7", Published by ASCE Press, 1994.
8. "Foundations and Earth Structures, Design Manual 7.2", by Department of Navy Naval Facilities
Engineering Command, May 1982, Revalidated by Change l September ) 986.
9. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and I.M. Idriss, 1982.
15