HomeMy WebLinkAboutCDP 2018-0038; SELVIDGE RESIDENCE; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2018-09-21VI
CHR-ISTIAN WHEELEft
ENGINEEKING
REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
PROPOSED SELVIDGE RESIDENCE
5170 CARLSBAD BOULEVARD
CARLSBAD, CALIFORNIA
PREPARED FOR:
PAULA SELVIDGE
2604 TRONA WAY
CARLSBAD, CALIFORNIA 92009 RECIEVED
AUG 2i 2C19
LAND DEVELOPMENT
ENGINEERING
PREPARED BY:
CHRISTIAN WHEELER ENGINEERING
3980 HOME AVENUE
SAN DIEGO, CALIFORNIA 92105
3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701
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CHRiSTIAN WHEELER,
ENGINEEftING
September 21, 2018
Paula Selvidge CWE 2180441.02
2604 Trona Way
Carlsbad, California 92009
Subject: Report of Preliminary Geotechnical Investigation
Proposed Selvidge Residence, 5170 Carlsbad Boulevard, Carlsbad, California
Dear Mrs. Selvidge:
In accordance with your request and our proposal dated August 1, 2018, we have completed a
geotechnical investigation for the subject project. We are presenting herewith a report of our findings
and recommendations.
It is our professional opinion and judgment that no geotechnical conditions exist on the subject
property that would preclude the construction of the proposed residence provided the
recommendations presented herein are implemented.
If you have questions after reviewing this report, please do not hesitate to contact our office. This
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opportunity to be of professional service is sincerely appreciated.
Respectfully submitted,
CHRISTIAN HEELER ENGINEERING
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Daniel .A 6037
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I ec: hfgeek@gmail.com
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DANIEL J. 9. FLOWERS 0
No.2686 Fn
9/21/18
Daniel J. Flowers, CEG #2686
1 398O Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701
TABLE OF CONTENTS
I Page
Introduction and Project Description.....................................................................................................1
Scopeof Services.....................................................................................................................................2
Findings..................................................................................................................................................3 I SiteDescription...................................................................................................................................3
General Geology and Subsurface Conditions......................................................................................3
I Geologic Setting and Soil Description.............................................................................................3
OldParalic Deposits ....................................................................................................................4
Groundwater...................................................................................................................................4
I
Tectonic Setting...............................................................................................................................4
GeneralGeologic Hazards ..................................................................................................................5
General............................................................................................................................................5
I Surface Rupture...............................................................................................................................5
SlopeStability..................................................................................................................................5
Liquefaction.....................................................................................................................................5
I Flooding ..........................................................................................................................................5
Tsunamis.........................................................................................................................................5
Seiches.............................................................................................................................................6
Conclusions............................................................................................................................................6
Recommendations..................................................................................................................................7
Gradingand Earthwork......................................................................................................................7
I
General............................................................................................................................................7
Pregrade Meeting.............................................................................................................................7
Observationof Grading...................................................................................................................7 ' Clearing and Grubbing....................................................................................................................8
SitePreparation...............................................................................................................................8
ExcavationCharacteristics...............................................................................................................8
I Processing of Fill Areas ...................................................................................................................8
Compactionand Method of Filling..................................................................................................9
SurfaceDrainage..............................................................................................................................9
I Temporary Cut Slopes......................................................................................................................10
TemporaryShoring...........................................................................................................................10
General..........................................................................................................................................10 ' Foundations......................................................................................................................................11
General..........................................................................................................................................11
Dimensions................................................................................................................................11 ' Bearing Capacity.........................................................................................................................11
FootingReinforcing....................................................................................................................11
LateralLoad Resistance...............................................................................................................11
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Foundation Excavation Observation...............................................................................................12
SettlementCharacteristics .............................................................................................................12
ExpansiveCharacteristics................................................................................................................12
I Soluble Sulfates..............................................................................................................................12
FoundationPlan Review ................................................................................................................12
SeismicDesign Factors ..................................................................................................................13
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CWE 2180441.02
Proposed Selvidge Residence
5170 Carlsbad Boulevard
Carlsbad, California
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On-Grade Slabs .13
General..........................................................................................................................................13
InteriorFloor Slabs.........................................................................................................................14
Under-Slab Vapor Retarders .......................................................................................................... 14
ExteriorConcrete Flatwork..........................................................................................................14
EarthRetaining Walls.......................................................................................................................15
Foundations...................................................................................................................................15
PassivePressure.............................................................................................................................15
ActivePressure..............................................................................................................................15
Waterproofing and Wall Drainage Systems ....................................................................................15
Backfill........................................................................................................................................... 16
Limitations...........................................................................................................................................16
Review, Observation and Testing.....................................................................................................16
Uniformityof Conditions.................................................................................................................16
Changein Scope................................................................................................................................17
TimeLimitations ..............................................................................................................................17
ProfessionalStandard........................................................................................................................17
Client's Responsibility......................................................................................................................17
FieldExplorations................................................................................................................................18
LaboratoryTesting...............................................................................................................................18
ATTACHMENTS
TABLES
Table I
Table II
FIGURES
Figure 1
PLATES
Plate 1
Plate 2
APPENDICES
$ Appendix A
Appendix B
I:
Appendix C
Appendix D
Shoring Design Parameters
Seismic Design Parameters, 2016 CBC
Site Vicinity Map, Follows Page 1
Site Plan & Geotechnical Map
Retaining Wall Subdrain
Subsurface Explorations
Laboratory Test Results
References
Recommended Grading Specifications-General Provisions
1
CWE 2180441.02
Proposed Selvidge Residence
5170 Carlsbad Boulevard
Carlsbad, California
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CHR-ISTIAN WHEELER.
ENCINEEftING
PRELIMINARY GEOTECHNICAL INVESTIGATION
PROPOSED SELVIDGE RESIDENCE
5170 CARLSBAD BOULEVARD
CARLSBAD, CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of a preliminary geotechnical investigation performed for proposed
residential structure to be located at 5170 Carlsbad Boulevard, Carlsbad, California. The following
Figure No. 1 presents a vicinity map showing the location of the property.
We understand that the existing structure and associated improvements on-site are to be demolished. A
new two- and three-story residential structure that will include an underground level is proposed. We
anticipate that the proposed structure will be of concrete and/or masonry and wood-frame
construction with on-grade concrete floor slabs, and will be supported by conventional shallow
foundations. Grading to accommodate the proposed improvements is expected to consist of cuts of up
to about 12 feet from existing site grade.
To assist in the preparation of this report, we were provided with an undated set of miscellaneous plans
prepared by Stephen Dalton Architects, and a topographic survey prepared by Baker Land Surveys,
Inc., dated March 8, 2018. A copy of a site plan included in the set was used as a base map for our Site
Plan and Geologic Map, and is included herein as Plate No. 1.
This report has been prepared for the exclusive use of Paula Selvidge, and her design consultants, for
specific application to the project described herein. Should the project be modified, the conclusions
and recommendations presented in this report should be reviewed by Christian Wheeler Engineering
for conformance with our recommendations and to determine whether any additional subsurface
investigation, laboratory testing and/or recommendations are necessary. Our professional services
have been performed, our findings obtained and our recommendations prepared in accordance with
3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701
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SITE VICINITY
Op'nSt reet Map COM ti butors
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DATE: SEPTEMBER 2018
BY: SR[)
SELVII)GE RESIDENCE
5170 CARLSBAD AVENCI
CARLSBAD, CALIFORNIA
JOB NO.: 2180441.02
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CWE 2180441.02 September 21, 2018 Page No. 2
generally accepted engineering principles and practices. This warranty is in lieu of all other warranties,
expressed or implied.
SCOPE OF SERVICES
Our preliminary geotechnical investigation consisted of surface reconnaissance, subsurface exploration,
obtaining representative soil samples, laboratory testing, analysis of the field and laboratory data, and
- review of relevant geologic literature. Our scope of service did not include assessment of hazardous
substance contamination, recommendations to prevent floor slab moisture intrusion or the formation
of mold within the structures, evaluation or design of storm water infiltration facilities, or any other
I services not specifically described in the scope of services presented below.
More specifically, the intent of our proposed investigation was to:
I . Drill two small diameter borings at the site with a limited access, tripod mounted drill rig to
explore the existing soil conditions and obtain soil samples for laboratory testing.
I . Backfill the boring holes using a grout or a grout/bentonite mix as required by the County of
San Diego Department of Environmental Health.
Evaluate, by laboratory tests and our past experience with similar soil types, the engineering
properties of the various soil strata that may influence the proposed construction, including
I bearing capacities, expansive characteristics and settlement potential.
. Describe the general geology at the site, including possible geologic hazards that could have an
effect on the proposed construction, and provide the seismic design parameters as required by
the 2016 edition of the California Building Code.
I
. Address potential construction difficulties that may be encountered due to soil conditions,
groundwater or geologic hazards, and provide geotechnical recommendations to deal with
these difficulties.
Provide site preparation and grading recommendations for the anticipated work.
I . Provide shored and unshored temporary cut slope recommendations.
Provide foundation recommendations for the type of construction anticipated and develop soil
engineering design criteria for the recommended foundation designs.
Provide design parameters for restrained and unrestrained retaining walls.
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C'WE 2180441.02 September 21, 2018 Page No. 3
Provide a preliminary findings and foundation recommendations report based on a site
reconnaissance and our general knowledge of the geotechnical conditions in the site vicinity.
Provide a preliminary geotechnical report that presents the results of our investigation which
includes a plot plan showing the location of our subsurface explorations, excavation logs,
laboratory test results, and our conclusions and recommendations for the proposed project.
Although a test for the presence of soluble sulfates within the soils that may be in contact with
reinforced concrete was performed as part of the scope of our services, it should be understood
Christian Wheeler Engineering does not practice corrosion engineering. If a corrosivity analysis is
considered necessary, we recommend that the client retain an engineering firm that specializes in this
field to consult with them on this matter. The results of our sulfate testing should only be used as a
guideline to determine if additional testing and analysis is necessary.
FINDINGS
SITE DESCRIPTION
The subject site is a rectangular-shaped, developed residential lot located at 5170 Carlsbad Boulevard,
Carlsbad, California. The lot is bounded to the west by Carlsbad Boulevard, and is otherwise bounded
by developed residential lots. The site currently supports a residential structure. Topographically, the
majority of the site is flat-lying. Elevations range from about 55 feet along the western property line to
about 58 feet at the southeastern corner of the site.
GENERAL GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal
Plains Physiographic Province of San Diego County. Based upon the findings of our subsurface
explorations and review of readily available, pertinent geologic and geotechnical literature, it was
determined that the site is generally underlain by old paralic deposits. These materials are described
below:
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CWE 2180441.02 September 21, 2018 Page No. 4
OLD PARALIC DEPOSITS (Qop): Quaternary-age old paralic (marine terrace) deposits were
found to underlie the subject site to a depth of about at least 19.5 feet from existing grade. As
encountered in our borings, these materials generally consisted of light brown, orangish-brown,
and brown, dry to moist, silty sand (SM) to a depth of about 91/2 feet and 7 feet below existing
grade, in borings B-i and B-2, respectively. Below said depth the old paralic deposits consist of
poorly graded sand with silt (SP-SM). The old paralic deposits in boring B-i were found to be
very dense. In boring B-2 the old paralic deposits were found to be medium dense to a depth of
about 7 feet below existing grade. Below said depth these materials were dense, becoming very
dense at a depth of about 17 feet below existing grade. The old paralic deposits judged to have a
very low Expansion Index (El <20).
GROUNDWATER: No groundwater or seepage was encountered in our subsurface explorations. We
do not expect any significant groundwater related conditions during or after the proposed construction.
However, it should be recognized that minor groundwater seepage problems might occur after
construction and landscaping are completed, even at a site where none were present before
construction. These are usually minor phenomena and are often the result of an alteration in drainage
patterns and/or an increase in irrigation water. Based on the anticipated construction and the
permeability of the on-site soils, it is our opinion that any seepage problems that may occur will be
minor in extent. It is further our opinion that these problems can be most effectively corrected on an
individual basis if and when they occur.
TECTONIC SETTING: It should be noted that much of Southern California, including the San
Diego County area, is characterized by a series of Quaternary-age fault zones that consist of several
individual, en echelon faults that generally strike in a northerly to northwesterly direction. Some of
these fault zones (and the individual faults within the zone) are classified as active while others are
classified as only potentially active according to the criteria of the California Division of Mines and
Geology. Active fault zones are those which have shown conclusive evidence of faulting during the
Holocene Epoch (the most recent 11,000 years) while potentially active fault zones have demonstrated
movement during the Pleistocene Epoch (11,000 to 1.6 million years before the present) but no
movement during Holocene time. Inactive faults are those faults that can be demonstrated to have no
movement in the past 1.6 million years.
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CWE 2180441.02 September 21, 2018 Page No. 5
It should be recognized that the active Newport Inglewood-Rose Canyon Fault Zone is located
approximately 2 miles northwest of the site. Other active fault zones in the region that could possibly
affect the site include the Coronado Bank, San Diego Trough, and San Clemente Fault Zones to the
west; the Palos Verdes Fault Zone to the northwest; and the Elsinore, San Jacinto and San Andreas
Fault Zones to the northeast.
GENERAL GEOLOGIC HAZARDS
GENERAL: The site is located in an area where the risks due to significant geologic hazards are
relatively low. No geologic hazards of sufficient magnitude to preclude the construction of the subject
project are known to exist. In our professional opinion and to the best of our knowledge, the site is
suitable for the proposed improvements.
SURFACE RUPTURE: There are no known active faults that traverse the subject site; therefore, the
risk for surface rupture at the subject site is considered low.
SLOPE STABILITY: As part of this investigation we reviewed the publication, "Landslide Hazards in
the Northern Part of the San Diego Metropolitan Area" by Tan and Giffen, 1995. This reference is a
comprehensive study that classifies San Diego County into areas of relative landslide susceptibility.
The subject site is located in Area 2, which is considered to be "marginally susceptible" to slope failures.
Based on our findings and the proposed construction, it is our opinion that the likelihood of slope
stability related problems at the site is low.
LIQUEFACTION: The earth materials underlying the site are not considered subject to liquefaction
due to such factors as soil density, grain-size distribution, the absence of shallow groundwater
conditions.
FLOODING: As delineated on the Flood Insurance Rate Map (FIRM), panel 06073C0764G prepared
by the Federal Emergency Management Agency, the site is located within a minimal flood hazard area.
TSUNAMIS: Tsunamis are great sea waves produced by a submarine earthquake, submarine
landslides or volcanic eruption. Historically, the San Diego area has been relatively free of tsunami-
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related hazards and tsunamis reaching San Diego have generally been well within the normal tidal
range. It is thought that the wide continental margin off the coast acts to diffuse and reflect the wave
energy of remotely generated tsunamis. The largest historical tsunami to reach San Diego's coast was
4.6 feet high, generated by the 1960 earthquake in Chile. A lack of knowledge about the offshore fault
systems makes it difficult to assess the risk due to locally generated tsunamis.
The site is loacted above the Tsunami Inundation area and Inundation Line as presented on the
Oceanside and San Luis Rey Quadrangles of the Tsunami Inundation Map for Emergency Planning
(CalEMA, 2009). Furthermore, given the elevation of the site, the risk of damage to the proposed site
improvements from a tsunamis is considered to be low.
SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or
reservoirs. Due to the site's location, it will not be affected by seiches.
CONCLUSIONS
In general, it is our professional opinion and judgment that the subject property is suitable for the
construction of the proposed structure provided the recommendations presented herein are
implemented. The main geotechnical conditions affecting the proposed project consist of potentially
compressible old paralic deposits, a cut/fill transition under the proposed structure, and temporary cut
slopes. These conditions are discussed hereinafter.
The site is underlain by a relatively thin layer of potentially compressible old paralic deposits. As
encountered in our subsurface explorations, these materials extend to a maximum depth of about 2 feet
from existing grade (boring B-2). However, they may be deeper in areas of the site not investigated.
These soils are considered unsuitable, in their present condition, for the support of settlement sensitive
improvements. The potentially compressible materials will require removal and replacement as
compacted fill where underling proposed settlement sensitive improvements. In addition, the old
paralic deposits in boring B-2, although medium dense, were found to be significantly less dense than
those encountered in boring B-i. Furthermore, some of the old paralic deposits may be collapsible. In
order to provide for a more homogeneous foundation soil condition, it is recommended that these
materials be removed as recommend hereinafter. It is anticipated that some of these materials will be
removed as part of the proposed grading.
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CWE 2180441.02 September 21, 2018 Page No. 7
A cut-fill transition will occur under the proposed structure due to the recommended site preparation
and proposed grading. Cut-fill transitions may result in differential settlements detrimental to the
propose structure. In order to mitigate this condition, special site preparation consideration is
recommended hereinafter.
Temporary cut slopes up to about 12 feet in depth (including footing excavation) are anticipated for
the proposed basement construction. Due to the characteristics of some of the old paralic deposits,
flatter than usual temporary cut slopes are recommended. In addition, it is anticipated that some
temporary shoring may be necessary for proposed basement construction.
The site is located in an area that is relatively free of geologic hazards that will have a significant effect
on the proposed construction. The most likely geologic hazard that could affect the site is ground
shaking due to seismic activity along one of the regional active faults. However, construction in
accordance with the requirements of the most recent edition of the California Building Code and the
local governmental agencies should provide a level of life-safety suitable for the type of development
proposed.
RECOMMENDATIONS
GRADING AND EARTHWORK
GENERAL: All grading should conform to the guidelines presented in the current edition of the
California Building Code, the minimum requirements of the City of Carlsbad, and the recommended
Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the
text of this report.
PREGRADE MEETING: It is recommended that a pre-grade meeting including the grading
contractor, the client, and a representative from Christian Wheeler Engineering be performed, to
discuss the recommendations of this report and address any issues that may affect grading operations.
OBSERVATION OF GRADING: Continuous observation by the Geotechnical Consultant is
essential during the grading operation to confirm conditions anticipated by our investigation, to allow
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CWE 2180441.02 September 21, 2018 Page No. 8
adjustments in design criteria to reflect actual field conditions exposed, and to determine that the
grading proceeds in general accordance with the recommendations contained herein.
CLEARING AND GRUBBING: Site preparation should begin with the demolition of existing
improvements. The resulting debris and any existing vegetation and other deleterious materials in areas
to receive proposed improvements or new fill soils should be removed from the site.
SITE PREPARATION: It is recommended that potentially compressible and collapsible old paralic
deposits as well as soils disturbed during demolition underlying the proposed structure, associated
improvements, and new fills should be removed and replaced as compacted fill. Based on our findings,
it is anticipated that the maximum removal depth will be about 2 feet below existing grade. In
addition, old paralic deposits within 4 feet from existing or proposed grade should be undercut. This
recommendation does not apply to the basement portion of the structure. Deeper removals may be
necessary in areas of the site not investigated or due to unforeseen conditions. Lateral removal limits
should extend at least 5 feet from the perimeter of the structure, any settlement sensitive
improvements, and new fills or equal to removal depth, whichever is more. No removals are
recommended beyond property lines. The removals and undercuts should be performed in such a way
as to provide for a continuous contact between the fill and old paralic deposits that drains away from
the proposed structure, and avoids adjacent zones with different undercut depths that may impair
subsurface drainage. All excavated areas should be approved by the geotechnical engineer or his
representative prior to replacing any of the excavated soils. The excavated materials can be replaced as
properly compacted fill in accordance with the recommendations presented in the "Compaction and
Method of Filling" section of this report.
EXCAVATION CHARACTERISTICS: The old paralic deposits underlying the site at proposed
basement elevations was found to be in a very dense condition. In addition, some of these materials are
friable. It is anticipated that excavations in these materials may be performed with heavy duty
conventional grading equipment. However, excavations with light trenching equipment may be
difficult.
PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new
improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified
CWE 2180441.02 September 21, 2018 Page No. 9
to a depth of 12 inches, watered thoroughly, and compacted to at least 90 percent relative compaction.
This recommendation applies to the area of the site outside the perimeter of the proposed basement.
COMPACTION AND METHOD OF FILLING: In general, all structural fill placed at the site,
including should be compacted to a relative compaction of at least 90 percent of its maximum laboratory
dry density as determined by ASTM Laboratory Test D1557. However, retaining wall backfill and
structural fill underlying the proposed structure should be compacted to at least 95%. Fills should be
placed at or slightly above optimum moisture content, in lifts six to eight inches thick, with each lift
compacted by mechanical means. Fills should consist of approved earth material, free of trash or debris,
roots, vegetation, or other materials determined to be unsuitable by the Geotechnical Consultant. Fill
material should be free of rocks or lumps of soil in excess of 3 inches in maximum dimension.
Utility trench backfill within 5 feet of the proposed structure and beneath all concrete flatwork or
pavements should be compacted to a minimum of 90 percent of its maximum dry density.
SURFACE DRAINAGE: The drainage around the proposed improvements should be designed to
collect and direct surface water away from proposed improvements toward appropriate drainage
facilities. Rain gutters with downspouts that discharge runoff away from the structure into controlled
drainage devices are recommended.
The ground around the proposed improvements should be graded so that surface water flows rapidly
away from the improvements without ponding. In general, we recommend that the ground adjacent to
structure slope away at a gradient of at least 5 percent for a minimum distance of 10 feet. If the minimum
distance of 10 feet cannot be achieved, an alternative method of drainage runoff away from the building
at the termination of the 5 percent slope will need to be used. Swales and impervious surfaces that are
located within 10 feet of the building should have a minimum slope of 2 percent. Pervious hardscape
surfaces adjacent to structures should be similarly graded.
Drainage patterns provided at the time of construction should be maintained throughout the life of the
proposed improvements. Site irrigation should be limited to the minimum necessary to sustain
landscape growth. Over watering should be avoided. Should excessive irrigation, impaired drainage, or
unusually high rainfall occur, zones of wet or saturated soil may develop.
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CWE 2180441.02 September 21, 2018 Page No. 10
TEMPORARY CUT SLOPES
The contractor is solely responsible for designing and constructing stable, temporary excavations and
will need to shore, slope, or bench the sides of trench excavations as required to maintain the stability
of the excavation sides. The contractor's "competent person", as defined in the OSHA Construction
Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as
part of the contractor's safety process. We anticipate that the existing on-site soils will consist of Type
C material. Our firm should be contacted to observe all temporary cut slopes during grading to
ascertain that no unforeseen adverse conditions exist. No surcharge loads such as foundation loads, or
soil or equipment stockpiles, vehicles, etc. should be allowed within a distance from the top of
temporary slopes equal to half the slope height.
TEMPORARY SHORING
GENERAL: Shoring may be necessary for the proposed construction. It is anticipated that the
shoring system will utilize soldier beams with wooden lagging. The following design parameters may
be assumed to calculate earth pressures on shoring.
Angle of friction 300
Apparent cohesion 200 pounds per square foot
Soil unit weight 115 pounds per cubic foot (pcf)
Active pressures can be applied to shoring that is capable of rotating 0.002 radians. At-rest pressures
should be applied to a shoring system that is unyielding and not able to rotate. These values do not
include surcharge loads. Construction surcharge loads should be evaluated on a case-by-case basis.
Vertical and lateral movements of the temporary shoring are expected to be small assuming an
adequate lateral support system.
September 21, 2018 CWE 2180441.02
I FOUNDATIONS
Page No. 11
GENERAL: Based on our findings and engineering judgment, the proposed structure may be
supported by conventional shallow continuous and isolated spread footings. The following
recommendations are considered the minimum based on the anticipated soil conditions, and are not
intended to be lieu of structural considerations. All foundations should be designed by a qualified
engineer.
DIMENSIONS: Spread footings supporting the proposed structure should be embedded at least 18
inches below lowest adjacent finish pad grade. Spread footings supporting light miscellaneous exterior
footings should be embedded at least 12 inches below lowest adjacent finish pad grade. Continuous and
isolated footings should have a minimum width of 12 inches and 24 inches, respectively. Retaining wall
footings should be at least 18 inches deep and 24 inches wide. Property line footings should also extend at
least 6 inches into competent old paralic deposits.
BEARING CAPACITY: Spread footings supporting the proposed structure with a minimum depth of
18 inches and a minimum width of 12 inches may be designed for an allowable soil bearing pressure of
2,000 pounds per square foot (psf). This value may be increased by 600 pounds per square foot for each
additional foot of embedment and 400 pounds per square foot for each additional foot of width up to a
maximum of 4,000 pounds per square foot. These values may be increased by one-third for combinations
of temporary loads such as those due to wind or seismic loads.
FOOTING REINFORCING: Reinforcement requirements for foundations should be provided by a
structural designer. However, based on the expected soil conditions, we recommend that the minimum
reinforcing for continuous footings consist of at least 2 No. 5 bars positioned near the bottom of the
footing and 2 No. 5 bars positioned near the top of the footing.
LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction
between the bottom of the footing and the supporting soil, and by the passive pressure against the
footing. The coefficient of friction between concrete and soil may be considered to be 0.30. The passive
resistance may be considered to be equal to an equivalent fluid weight of 300 pounds per cubic foot.
These values are based on the assumption that the footings are poured tight against undisturbed soil. If a
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C'WE 2180441.02 September 21, 2018 Page No. 12
combination of the passive pressure and friction is used, the friction value should be reduced by one-
third.
FOUNDATION EXCAVATION OBSERVATION: All footing excavations should be observed by
Christian Wheeler Engineering prior to placing of forms and reinforcing steel to determine whether the
foundation recommendations presented herein are followed and that the foundation soils are as
anticipated in the preparation of this report. All footing excavations should be excavated neat, level, and
square. All loose or unsuitable material should be removed prior to the placement of concrete.
SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected
to be less than about 1 inch and 1 inch over 40 feet, respectively, provided the recommendations
presented in this report are followed. It should be recognized that minor cracks normally occur in
concrete slabs and foundations due to concrete shrinkage during curing or redistribution of stresses,
therefore some cracks should be anticipated. Such cracks are not necessarily an indication of excessive
vertical movements.
EXPANSIVE CHARACTERISTICS: The prevailing foundation soils are assumed to have a very low
expansive potential (El <20). The recommendations within this report reflect these conditions.
SOLUBLE SULFATES: The water soluble sulfate content of a selected soil sample from the site was
determined in accordance with California Test Method 417. The test results indicate that the soil
sample had a soluble sulfate content of 0.006 percent. Soils with a soluble sulfate content of less than
0.1 percent are considered to be negligible. However, it should be recognized that the sulfate content
of surficial soils may increase with time due to soluble sulfate in the irrigation water or fertilized use.
FOUNDATION PLAN REVIEW: The final foundation plan and accompanying details and notes
should be submitted to this office for review. The intent of our review will be to verify that the plans
used for construction reflect the minimum dimensioning and reinforcing criteria presented in this section
and that no additional criteria are required due to changes in the foundation type or layout. It is not our
intent to review structural plans, notes, details, or calculations to verify that the design engineer has
correctly applied the geotechnical design values. It is the responsibility of the design engineer to
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September 21, 2018 CWE 2180441.02 Page No. 13
properly design/specify the foundations and other structural elements based on the requirements of
the structure and considering the information presented in this report.
SEISMIC DESIGN FACTORS
The seismic design factors applicable to the subject site are provided below. The seismic design factors
were determined in accordance with the 2016 California Building Code. The site coefficients and
adjusted maximum considered earthquake spectral response acceleration parameters are presented in
the following Table I.
TABLE II: SEISMIC DESIGN FACTORS
Site Coordinates: Latitude
Longitude
33.1310
-117.3340
Site Class D
Site Coefficient Fa 1.031
Site Coefficient F 1.549
Spectral Response Acceleration at Short Periods Ss 1.173 g
Spectral Response Acceleration at 1 Second Period Si 0.451 g
SMSFaSs 1.209 g
SM1=FSi 0.699 g
SDs =2/3*SMs 0.806 g
SD1 =2/3*SMI 0.446 g
Probable ground shaking levels at the site could range from slight to moderate, depending on such
factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site
will experience the effects of at least one moderate to large earthquake during the life of the proposed
improvements.
ON-GRADE SLABS
GENERAL: It is our understanding that the floor system of the proposed structure will consist of a
concrete slab-on-grade. The following recommendations are considered the minimum slab requirements
based on the soil conditions and are not intended in lieu of structural considerations. These
recommendations assume that the site preparation recommendations contained in this report are
implemented.
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CWE 2180441.02 September 21, 2018 Page No. 14
I INTERIOR FLOOR SLABS: The minimum basement slab thickness should be 4 inches (actual) and
I the slab should be reinforced with at least No. 3 bars spaced at 18 inches on center each way. The
minimum slab thickness for the on-grade portion of the structure should be 5 inches (actual) and the
I slab should be reinforced with at least No. 4 bars spaced at 18 inches on center each way. Slab
reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid-
height in the floor slab. The slab reinforcement should extend down into the perimeter footings at
least 6 inches.
I UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of
moisture vapor from the subsoil through the interior slabs where it can potentially damage the interior I floor coverings. Local industry standards typically include the placement of a vapor retarder, such as
plastic, in a layer of coarse sand placed directly beneath the concrete slab. Two inches of sand are I typically used above and below the plastic. The vapor retarder should be at least 15-mil Stegowrap® or
similar material with sealed seams and should extend at least 12 inches down the sides of the interior
and perimeter footings. The sand should have a sand equivalent of at least 30, and contain less than
10% passing the Number 100 sieve and less than 5% passing the Number 200 sieve. The membrane
I should be placed in accordance with the recommendation and consideration of ACT 302, "Guide for
Concrete Floor and Slab Construction" and ASTM E1643, "Standards Practice for Installation of
I Water Vapor Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs." It is the
flooring contractor's responsibility to place floor coverings in accordance with the flooring
I manufacturer specifications.
I EXTERIOR CONCRETE FLATWORK: Exterior concrete slabs on grade should have a minimum
thickness of 4 inches and be reinforced with at least No. 4 bars placed at 18 inches on center each way
I (ocew). Driveway slabs should have a minimum thickness of 5 inches and be reinforced with at least
No. 4 bars placed at 12 inches ocew. Driveway slabs should be provided with a thickened edge a least
12 inches deep and 6 inches wide. Special consideration is needed to slabs adjacent to swimming pools
and spas due to potential chloride exposure. All slabs should be provided with weakened plane joints
in accordance with the American Concrete Institute (ACT) guidelines. Special attention should be paid
to the method of concrete curing to reduce the potential for excessive shrinkage cracking. It should be
I recognized that minor cracks occur normally in concrete slabs due to shrinkage. Some shrinkage
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CWE 2180441.02 September 21, 2018 Page No. 15
cracks should be expected and are not necessarily an indication of excessive movement or structural
distress.
EARTH RETAINING WALLS
FOUNDATIONS: Foundations for any proposed retaining walls should be constructed in
accordance with the foundation recommendations presented previously in this report.
PASSIVE PRESSURE: The passive pressure for the anticipated foundation soils may be considered to
be 300 pounds per square foot per foot of depth. The upper foot of embedment should be neglected
when calculating passive pressures, unless the foundation abuts a hard surface such as a concrete slab.
The passive pressure may be increased by one-third for seismic loading. The coefficient of friction for
concrete to soil may be assumed to be 0.30 for the resistance to lateral movement. When combining
frictional and passive resistance, the friction should be reduced by one-third.
ACTIVE PRESSURE: The active soil pressure for the design of "unrestrained" and "restrained" earth
retaining structures with level backfill may be assumed to be equivalent to the pressure of a fluid
weighing 40 and 60 pounds per cubic foot, respectively. These pressures do not consider any other
surcharge. If any are anticipated, this office should be contacted for the necessary increase in soil
pressure. These values are based on a drained backfill condition.
Seismic lateral earth pressures may be assumed to equal an inverted triangle starting at the bottom of
the wall with the maximum pressure equal to 9.5H pounds per square foot (where H = wall height in
feet) occurring at the top of the wall.
WATERPROOFING AND WALL DRAINAGE SYSTEMS: The need for waterproofing should
be evaluated by others. If required, the project architect should provide (or coordinate) waterproofing
details for the retaining walls. The design values presented above are based on a drained backfill
condition and do not consider hydrostatic pressures. The retaining wall designer should provide a
detail for a wall drainage system. Typical retaining wall drain system details are presented as Plate No.
2 of this report for informational purposes. Additionally, outlets points for the retaining wall drain
system should be coordinated with the project civil engineer.
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BACKFILL: Retaining wall backfill soils should be compacted to at least 90 percent relative
compaction. However, retaining wall backfill underlying settlement sensitive improvements should be
compacted to at least 95%.Expansive or clayey soils should not be used for backfill material. The wall
should not be backfilled until the masonry has reached an adequate strength.
LIMITATIONS
REVIEW, OBSERVATION AND TESTING
The recommendations presented in this report are contingent upon our review of final plans and
specifications. Such plans and specifications should be made available to the geotechnical engineer and
engineering geologist so that they may review and verify their compliance with this report and with
the California Building Code.
It is recommended that Christian Wheeler Engineering be retained to provide continuous soil
engineering services during the earthwork operations. This is to verify compliance with the design
concepts, specifications or recommendations and to allow design changes in the event that subsurface
conditions differ from those anticipated prior to start of construction.
UNIFORMITY OF CONDITIONS
The recommendations and opinions expressed in this report reflect our best estimate of the project
requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface
exploration locations and on the assumption that the soil conditions do not deviate appreciably from
those encountered. It should be recognized that the performance of the foundations and/or cut and fill
slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur
in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may
be encountered during site development should be brought to the attention of the geotechnical
engineer so that he may make modifications if necessary.
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CWE 2180441.02 September 21, 2018 Page No. 17
CHANGE IN SCOPE
This office should be advised of any changes in the project scope or proposed site grading so that we
may determine if the recommendations contained herein are appropriate. This should be verified in
writing or modified by a written addendum.
TIME LIMITATIONS
The findings of this report are valid as of this date. Changes in the condition of a property can,
however, occur with the passage of time, whether they be due to natural processes or the work of man
on this or adjacent properties. In addition, changes in the Standards-of-Practice and/or Government
Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in
part by changes beyond our control. Therefore, this report should not be relied upon after a period of
two years without a review by us verifying the suitability of the conclusions and recommendations.
PROFESSIONAL STANDARD
In the performance of our professional services, we comply with that level of care and skill ordinarily
exercised by members of our profession currently practicing under similar conditions and in the same
locality. The client recognizes that subsurface conditions may vary from those encountered at the
locations where our borings, surveys, and explorations are made, and that our data, interpretations,
and recommendations be based solely on the information obtained by us. We will be responsible for
those data, interpretations, and recommendations, but shall not be responsible for the interpretations
by others of the information developed. Our services consist of professional consultation and
observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in
connection with the work performed or to be performed by us, or by our proposal for consulting or
other services, or by our furnishing of oral or written reports or findings.
CLIENT'S RESPONSIBILITY
It is the responsibility of the Client, or her representatives, to ensure that the information and
recommendations contained herein are brought to the attention of the structural engineer and
CWE 2180441.02 September 21, 2018 Page No. 18
architect for the project and incorporated into the project's plans and specifications. It is further their
responsibility to take the necessary measures to insure that the contractor and his subcontractors carry
out such recommendations during construction.
FIELD EXPLORATIONS
Two subsurface explorations were made on August 13, 2018 at the locations indicated on the Site Plan
and Geotechnical Map included herewith as Plate No. 1. These explorations consisted of small diameter
borings drilled utilizing a portable drill rig. The fieldwork was conducted under the observation and
direction of our engineering geology personnel.
The explorations were carefully logged when made. The boring logs are presented on Appendix A. The
soils are described in accordance with the Unified Soils Classification. In addition, a verbal textural
description, the wet color, the apparent moisture, and the density or consistency is provided. The
density of granular soils is given as very loose, loose, medium dense, dense or very dense. The
consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard.
Relatively undisturbed drive samples were collected using a modified California sampler. The sampler,
with an external diameter of 3.0 inches, is lined with 1-inch long, thin, brass rings with inside
diameters of approximately 2.4 inches. The sample barrel was driven into the ground with the weight
of a 140-pound hammer falling 30 inches in general accordance with ASTM D 3550-84. The driving
weight is permitted to fall freely. The number of blows per foot of driving, or as indicated, are
presented on the boring logs as an index to the relative resistance of the sampled materials. The
samples were removed from the sample barrel in the brass rings, and sealed. Bulk samples of the earth
materials encountered were also collected. Samples were transported to our laboratory for testing.
LABORATORY TESTING
Laboratory tests were performed in accordance with the generally accepted American Society for Testing
and Materials (ASTM) test methods or suggested procedures. A brief description of the tests performed
and the subsequent results are presented in Appendix B.
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0 20 40'
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SCALE: 1" = 20'
CWE LEGEND
SB-2 BORING LOCATIONS
Qop OLD PARALIC DEPOSITS AO-1
SITE PLAN AND GEOLOGIC MAP
PROPOSED SELVIDGE RESIDENCE
5170 CARLSBAD AVENUE
CARLSBAD, CALIFORNIA
DATE: SEPTEMBER 2018 JOB NO.: 2180441.02
BY: SD PLATE NO.: 1
CHRISTIAN WHEELER
LNGI N ER INC
- 12" MIN. __®
6"MIN.
DETAIL DETAIL
6" MIN. - 6" MIN.
DETAIL DETAIL
NOTES AND DETAILS
GENERAL NOTES:
THE NEED FOR WATERPROOFING SHOULD BE EVALUATED BY OTHERS.
WATERPROOFING TO BE DESIGNED BY OTHERS (CWE CAN PROVIDE A DESIGN IF REQUESTED).
EXTEND DRAIN TO SUITABLE DISCHARGE POINT PER CIVIL ENGINEER.
DO NOT CONNECT SURFACE DRAINS TO SUBDRAIN SYSTEM.
DETAILS:
O 4-INCH PERFORATED PVC PIPE ON TOP OF FOOTING, HOLES UNDERLAY SUBDRAIN WITH AND CUT FABRIC BACK FROM 1 POSITIONED DOWNWARD SCHEDULE 6 (SDR 35, 40, OR EQUIVALENT). DRAINAGE PANELS AND WRAP FABRIC AROUND PIPE.
INCH OPEN-GRADED CRUSHED AGGREGATE. COLLECTION DRAIN (TOTAL DRAIN OR EQUIVALENT)
LOCATED AT BASE OF WALL DRAINAGE PANEL PER GEOFARBRIC WRAPPED COMPLETELY AROUND ROCK. MANUFACTURER'S RECOMMENDATIONS.
PROPERLY COMPACTED BACKFILL SOIL.
O WALL DRAINAGE PANELS (MIRADRAIN OR EQUIVALENT)
PLACED PER MANUFACTURER'S REC'S.
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PROPOSED SELVIDGE RESIDENCE
5170 CARLSBAD AVENUE
CANTILEVER RETAINING WALL ____________ CARLSBAD, CALIFORNIA
DRAINAGE SYSTEMS DATE: SEPTEMBER 2018 JOB NO.: 2180441.02
BY: SRD PLATE NO.: 2
MCI
CHRISTIAN WHEELER
ENGINEERING
Appendix A
Subsurface Explorations
LOG OF TEST BORING B-i
Sample Type and Laboratory Test Legend
SPT Standard 'Mi.. est DR Drive Ring ST Shelby Tube
Date Logged: 8/13/18 Equipment: Tripod MD Max Density DS Direct Shear
Logged By: DJF Bucket Ty;e: 6 Solid Flight SO4 Soluble Sulfates Con Consolidation
SA Sieve Analysis El Expansion Index
Existing Elevation: 57.0 feet Drive Type: 1401bs/30" drop HA Hydrorneter R-Val Resistance value
SE Sand Equivalent ChI Soluble Chlorides
Proposed Elevation: 48.0 feet Depth to Water: N/A P1 Plasticity Index Res pH & Resistivity
CP Collapse Potential SD Sample Density
o o o72 I-' 0
0 SUMMARY OF SUBSURFACE CONDITIONS .
(based on Unified Soil Classification System)
W4 Z5 0 0
04 Ln P0 U do
0 - SM Old Paralic Deposits (Qop): Light brown, dry, loose to medium dense, very
• -..... fine- to medium-grained, SILTY SAND, upper 12" highly weathered. 50/5" Cal
-
- : Orangish-brown, damp, very dense.
- -
50/5" Cal 4.6 100.7 CP
5--
10__ SM- Light brown to light orangish-brown, damp, very dense, very fine- to -
-
- -
SP medium-grained, poorly-graded SAND with silt, friable. 50/6 Cal 3.2 103 6 . CP
ii
15—-
-- /6"Cal 2.6 1014
- - Boring terminated at 16.5 feet.
- - No groundwater or seepage encountered.
20--
25--
30T -
Notes:
Symbol Legend PROPOSED SELVIDGE RESIDENCE
Groundwater Level During Drilling 5170 CARLSBAD AVENUE
Groundwater Level After Drilling CARLSBAD, CALIFORNIA
Apparent Seepage
CHRiSTIAN WHEELER. DATE: SEPTEMBER 2018 JOB NO.: 2180441.02
NoSainpleRecovery ENGINEERING
BY: SRD APPENDIX: A-I ** Non-Representative Blow Count
(rocks present)
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LOG OF TEST BORING B-2 SPTStandard ratio c. Sample Type and Laboratory Test Legend
'R Drive Ring ST Shelby Tube
Date Logged: 8/13/18 Equipment: Tripod MD Max Density DS Direct Shear
Logged By: DJF Bucket Ty;e: 6 Solid Flight SO4 Soluble Sulfates Con Consolidation
SA Sieve Analysis El Expansion Index
Existing Elevation: 56.0 feet Drive Type: 1401bs/30° drop al ResistanceJah
SE Sand Equivalent Chi Soluble rides
Proposed Elevation: 48.0 feet Depth to Water: N/A P1 Plasticity Index Res pH & Resistivity
CP Collapse Potential SD Sample Density
' ( 0 0 0 .-. z
' 0 ç SUMMARY OF SUBSURFACE CONDITIONS Z Z C. (based on Unified Soil Classification System)'
0 SM Old Paralic Deposits (Qop): Brown, dry, loose to medium dense, very fine- to SA
- - XT1. medium-grained, SILTY SAND, upper 2' highly weathered. MD
SO4
- -
. Light brown, damp, medium dense. 27 Cal DS
-
- 17 Cal 4.9 108.8 DS
5— - -
SP- Light brown to light orangish-brown, damp to moist, dense, very fine- to SA
- - SM medium-grained, poorly-graded, SAND with silt, friable.
-
- :- 39 Cal 6.0 112.7 SD
1011
11
42 Cal 4.0 104.7 SD 15— -
Very dense.
- - 64 Cal 3.8 110.2 SD
20-- Boring terminated at 19.5 feet.
- - No groundwater or seepage encountered.
25--
30--
Notes:
Symbol Legend PROPOSED SELVIDGE RESIDENCE
Groundwater Level During Drilling 5170 CARLSBAD AVENUE
V Groundwater Level After Drilling CARLSBAD, CALIFORNIA
Apparent Seepage
CHRJSTIAN WHEftEft DATE: SEPTEMBER 2018 JOB NO.: 2180441.02
NoSampleRecovesy ENGINEERING
BY: SRD APPENDIX: A-2 ** Non-Representative Blow Count
(rocks present)
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Appendix B
Laboratory Test Results
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Laboratory tests were performed in accordance with the generally accepted American Society for
Testing and Materials (ASTM) test methods or suggested procedures. Brief descriptions of the tests
performed are presented below:
CLASSIFICATION: Field classifications were verified in the laboratory by visual
examination. The final soil classifications are in accordance with the Unified Soil
Classification System and are presented on the exploration logs in Appendix A.
MOISTURE-DENSITY: MOISTURE-DENSITY: In-place moisture contents and dry
densities were determined for selected soil samples in accordance with ATM D 2937. The
results are summarized in the boring logs presented in Appendix A.
MAXIMUM DRY DENSITY AND OPTIUM MOISTURE CONTENT TEST: The
maximum dry density and optimum moisture content of a selected soil sample were determined
in the laboratory in accordance with ASTM D 1557, Method A.
DIRECT SHEAR: Direct shear tests were performed on selected samples of the on-site soils in
accordance with ASTM D 3080.
GRAIN SIZE DISTRIBUTION: The grain size distribution of selected samples was
determined in accordance with ASTM C136 and/or ASTM D 422.
COLLAPSE POTENTIAL: Collapse potential tests were performed on selected undisturbed
soil samples in accordance with ASTM D 5333.
SOLUBLE SULFATES: The soluble sulfate content of a selected soil sample was determined
in accordance with California Test Method 417.
N
CHRISTIAN WHEELER
ENGINE EKING
PROPOSED SELVIDGE RESIDENCE
5170 CARLSBAD AVENUE, CARLSBAD
BY: DBA I DATE: SEPT 2018
LAB SUMMARY
REPORT NO.:2180441.02 I FIGURE NO.: B-i
LABORATORY TEST RESULTS
PROPOSED SELVIDGE RESIDENCE
5170 CARLSBAD AVENUE
CARLSBAD, CALIFORNIA
MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557)
Sample Location Boring B-2 @ 0-5'
Sample Description Brown Silty Sand (SM)
Maximum Density 122.5 pcf
Optimum Moisture 9.2%
DIRECT SHEAR (ASTM D3080)
Sample Location Boring B-2 @ 0-5' Boring B-2 @ 0-5'
Sample Type Remolded to 90% Undisturbed
Friction Angle 300 30°
Cohesion 200 psf 200 psf
GRAIN SIZE DISTRIBUTION (ASTM D422)
Sample Location Boring B-2 @ 0-5' Boring B-3 @ 7'-12'
Sieve Size Percent Passing Percent Passing
#4 100 100
#8 100 100
#16 99 100
#30 92 92
#50 54 21
#100 32 10
#200 27 14
COLLAPSE POTENTIAL (ASTM D 5333)
Sample Location Boring B-i @ 41/2' Boring B-i @ 101/2'
Initial Moisture Content 4.6% 3.2%
Initial Density 100.7 pcf 103.6 pcf
Consolidation Before Water Added 3.9% 2.3%
Consolidation After Water Added 8.8% 2.9%
Final Moisture 17.1% 18.7%
SOLUBLE SULFATES (CALIFORNIA TEST 417)
Sample Location Boring B-2 @ 0-5'
Soluble Sulfate 0.006 % (SO4)
CWE 2180441.01 September 21, 2018 Plate No. B-2
1 Appendix C
H References
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CWE 2180441.02 September 21, 2018 Appendix C-i
1 REFERENCES
I California Emergency Management Agency - California Geological Society - University of Southern California,
2009, Tsunami Inundation Map for Emergency Planning, Oceanside and San Luis Rey Quadrangles, scale
1:24,000, dated June 1, 2009.
I Federal Emergency Management Agency, 2012, San Diego County, California and Incorporated Areas
Flood Insurance Rate Map, Panel 06073C0764G.
Historic Aerials, NETR Online, historicaerials.com
Jennings, C.W. and Bryant, W. A., 2010, Fault Activity Map, California Geological Survey, Geologic
Data Map No. 6, http://www.quake.ca.gov/gmaps/FAM/faultactivitymap.html
Kennedy, Michael P. and Tan, Siang S., 2007, Geologic Map of the Oceanside 30'x60' Quadrangle,
California, California Geologic Survey, Map No. 2.
Tan, S.S., 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San
Diego County, California, California Division of Mines and Geology Open-File Report 95-04.
I U.S. Geological Survey, U.S. Seismic Design Maps Web Application,
http://geohazards.usgs.gov/designmaps/us/application.php
U.S. Geological Survey, Quaternary Faults in Google Earth,
http://earthquake.usgs.gov/hazards/qfaults/google.php
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Appendix D
I Recommended Grading Specifications - General Provisions
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CWE 2180441.02 September 21, 2018 Appendix D, Page D-1
RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS
I PROPOSED SELVIDGE RESIDENCE
I 5170 CARLSBAD AVENUE
CARLSBAD, CALIFORNIA
GENERAL INTENT
The intent of these specifications is to establish procedures for clearing, compacting natural ground,
preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the
accepted plans. The recommendations contained in the preliminary geotechnical investigation report
and/or the attached Special Provisions are a part of the Recommended Grading Specifications and
shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall
only be used in conjunction with the geotechnical report for which they are a part. No deviation
from these specifications will be allowed, except where specified in the geotechnical report or in other
written communication signed by the Geotechnical Engineer.
OBSERVATION AND TESTING
Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the
earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer
or his representative provide adequate observation so that he may provide his opinion as to whether
or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist
the Geotechnical Engineer and to keep him appraised of work schedules, changes and new
information and data so that he may provide these opinions. In the event that any unusual conditions
not covered by the special provisions or preliminary geotechnical report are encountered during the
grading operations, the Geotechnical Engineer shall be contacted for further recommendations.
If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as
questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse
weather, etc., construction should be stopped until the conditions are remedied or corrected or he
shall recommend rejection of this work.
CWE 2180441.02 September 21, 2018 Appendix D, Page D-2
Tests used to determine the degree of compaction should be performed in accordance with the
following American Society for Testing and Materials test methods:
Maximum Density & Optimum Moisture Content - ASTM D1557
Density of Soil In-Place - ASTM D1556 or ASTM D2922
All densities shall be expressed in terms of Relative Compaction as determined by the foregoing
ASTM testing procedures.
PREPARATION OF AREAS TO RECEIVE FILL
All vegetation, brush and debris derived from clearing operations shall be removed, and legally
disposed of. All areas disturbed by site grading should be left in a neat and finished appearance, free
from unsightly debris.
After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6
inches, brought to the proper moisture content, compacted and tested for the specified minimum
degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural
ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its
maximum dry density.
When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1 vertical
unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent
formational soil. The lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width,
whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2)
percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall
be compacted prior to receiving fill as specified herein for compacted natural ground. Ground slopes
flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer.
Any abandoned buried structures encountered during grading operations must be totally removed.
All underground utilities to be abandoned beneath any proposed structure should be removed from
within 10 feet of the structure and properly capped off. The resulting depressions from the above
CWE 2180441.02 September 21, 2018 Appendix D, Page D-3
described procedure should be backfilled with acceptable soil that is compacted to the requirements of
the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or
leach lines, storm drains and water lines. Any buried structures or utilities not to be abandoned
should be brought to the attention of the Geotechnical Engineer so that he may determine if any
special recommendation will be necessary.
All water wells which will be abandoned should be backfilled and capped in accordance to the
requirements set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet
below finish grade or 3 feet below the bottom of footing whichever is greater. The type of cap will
depend on the diameter of the well and should be determined by the Geotechnical Engineer and/or a
qualified Structural Engineer.
FILL MATERIAL
Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of
vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material
to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils
are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation,
or soils with low strength characteristics may be thoroughly mixed with other soils to provide
satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any
import material shall be approved by the Geotechnical Engineer before being brought to the site.
PLACING AND COMPACTION OF FILL
Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches
in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow
the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each
layer shall be uniformly compacted to the specified minimum degree of compaction with equipment
of adequate size to economically compact the layer. Compaction equipment should either be
specifically designed for soil compaction or of proven reliability. The minimum degree of compaction
to be achieved is specified in either the Special Provisions or the recommendations contained in the
preliminary geotechnical investigation report.
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CWE 2180441.02 September 21, 2018 Appendix D, Page D-4
When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be ' carefully filled with soil such that the minimum degree of compaction recommended in the Special
Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non-
structural fills is discussed in the geotechnical report, when applicable.
I Field observation and compaction tests to estimate the degree of compaction of the fill will be taken
by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at
I the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is
at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the
Geotechnical Engineer and until the desired relative compaction has been obtained.
I Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment.
Compaction by sheepsfoot roller shall be at vertical intervals of not greater than four feet. In
I addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled.
Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been
I constructed. Slope compaction operations shall result in all fill material six or more inches inward
from the finished face of the slope having a relative compaction of at least 90 percent of maximum dry ' density or the degree of compaction specified in the Special Provisions section of this specification.
The compaction operation on the slopes shall be continued until the Geotechnical Engineer is of the
opinion that the slopes will be surficially stable.
I Density tests in the slopes will be made by the Geotechnical Engineer during construction of the
slopes to determine if the required compaction is being achieved. Where failing tests occur or other
field problems arise, the Contractor will be notified that day of such conditions by written I communication from the Geotechnical Engineer or his representative in the form of a daily field
1 report.
If the method of achieving the required slope compaction selected by the Contractor fails to produce I the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of
compaction is obtained, at no cost to the Owner or Geotechnical Engineer.
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CWE 2180441.02 September 21, 2018 Appendix D, Page D-5
CUT SLOPES
The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material
during the grading operations at intervals determined at his discretion. If any conditions not
anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a
potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during
grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer
to determine if mitigating measures are necessary.
Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or
steeper than that allowed by the ordinances of the controlling governmental agency.
ENGINEERING OBSERVATION
Field observation by the Geotechnical Engineer or his representative shall be made during the filling
and compaction operations so that he can express his opinion regarding the conformance of the
grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or
his representative or the observation and testing shall release the Grading Contractor from his duty to
compact all fill material to the specified degree of compaction.
SEASON LIMITS
Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy
rain, filling operations shall not be resumed until the proper moisture content and density of the fill
materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be
repaired before acceptance of work.
RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS
RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted
natural ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and
CWE 2180441.02 September 21, 2018 Appendix D, Page D-6
I parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative
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compaction.
I EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion
index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-2.
1 OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of
soil over 6 inches in diameter. Oversized materials should not be placed in fill unless I recommendations of placement of such material are provided by the Geotechnical Engineer. At least
40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve.
TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building I pad, the cut portion should be undercut a minimum of one foot below the base of the proposed
footings and recompacted as structural backfill. In certain cases that would be addressed in the
I geotechnical report, special footing reinforcement or a combination of special footing reinforcement
and undercutting may be required.
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