HomeMy WebLinkAboutCP 05-21; Cazadero Homes; Condo Permit (CP) (2)CHRISTIAN WHEELER
ENGINEERING
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REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
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PROPOSED RESIDENCES r 2817 AND 2819 CAZADERO DRIVE
CARLSBAD, CALIFORNIA
SUBMITTED TO:
CAZADERO HOMES, INC.
2954 HAWKS EYE PLACE
CARLSBAD, CALFIORNIA 92009
SUBMITTED BY:
CHRISTLVN WHEELER ENGINEERING
4925 MERCURY STREET
SAN DIEGO, CALIFORNIA 92111
4925 Mercury Street • San Diego, CA 92111 ^ 8.58-496-9760 FAX 858-496-9758
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June 29,2004
CHRISTIAN WHEELER
ENGINEER^ING
Cazadero Homes, Inc.
2954 Hawks Eye Place
Carlsbad, California 92009
CWE 2040602.1
Attention: Mx. Ron Paul
SUBJECT: REPORT OF PREUMINARY GEOTECHNICAL INVESTIGATION,
PROPOSED RESIDENCES, 2817-2819 CAZADERO DRIVE,
CARLSBAD, CALIFORNIA.
Dear Mr. Paul:
In accordance witli your request, we have completed a preliminary geotechnical investigation for the subject
property. We are presenting herewith our findings and recommendations.
No geotechnical conditions were found that would preclude the construction of the proposed residential project
provided the recommendations presented in this report are followed. Based on our investigation, we have
found tliat the site is underlain by artificial fills and slopewash underlain by Cretaceous-age Santiago Peak
Volcanics. The Santiago Peak Volcanics encountered in our investigation are generally medium dense to dense
and suitable to support the proposed construction. The existing artificial fill material appears to have been
properly compacted and properly benched into competent formational material and is, therefore, considered
suitable in its present condition to support settlement-sensitive improvements; however, the upper portions will
need to be scarified, moisture conditioned, and recompacted. The existing slopewash material is considered
unsuitable in its present condition to support settiement-sensitive improvements. As such, the slopewash will
need to be removed and be replaced as properly compacted fill material. This being accomplished, the
proposed residences can be supported by conventional spread foundations and with conventional concrete
slabs-on-grade.
No geologic hazards of sufficient magnitude to preclude development of the site as we presendy contemplate it
are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable from a
4925 Mercury Street -f San Diego, CA 92111 • 858-496-9760 • FAX 858-496-9758
C^'E 2040602.1 June 24, 2004 Page No. 2
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geologic perspective for tlie proposed constniction, provided die strucmre is designed in accordance ^^'ith tlie
requirements of die most recent edition of tlie Uniform BuUding Code and the local govemmental agencies.
Ifyou have any questions after reviewing this report, please do not hesitate to contact our office. Tliis
oppormnit)' to be of professional ser\'ice is sincerely appreciated.
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Respectfully submitted,
CHRISTIAN WHEELER ENGINEERING
If-
Charies H. Christian, R.G.E. #00215
CHC:CRB:scc:shv
cc: (6) Submitted
Curtis R. Burdett, C.E.G. #1090
TABLE OF CONTENTS
PAGE
Introduction and Project Description 1
Project Scope 2
Findings 3
Site Description 3
General Geology and Subsurface Conditions 3
Geologic Setting and Soil Description 3
Artificial Fill 4
Slopewash 4
Weathered Undifferentiated Santiago Peak Volcanics 4
Groundwater 4
Tectonic Setting 5
Geologic Hazards 5
Ground Shaking. 5
Surface Rupture 6
Landslide Potential and Slope Stability 6
Liquefaction 6
Flooding. 6
Tsunamis ; 6
Seiches .• 6
Conclusions 7
Recommendations 7
Grading and Earthwork 7
General 7
Observation of Grading 7
Clearing and Gmbbing 8
Site Preparation 8
Building Pad Undercuts 8
Processing of Fill Areas 8
Compaction and Method of Filling 8
Cut and Fill Slope Construction 9
Surface Drainage 9
Temporary Cut Slopes 10
Slope Stability 10
General 10
Erosion Control 10
Foundations 11
General , 11
Foundation Dimensions 11
Bearing Capacity 11
Footing Reinforcement 11
Lateral Load Resistance 11
Setdement Characteristics 11
Foundation Plan Review 12
Foundation Excavation Observation 12
Seismic Design Parameters 12
On-Grade Slabs 13
General 13
CWE 2040602.1
Proposed Residences
Cazadero Drive, Carlsbad, California
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Interior Floor Slabs 13
Moisture Protection for Interior Slabs 13
Exterior Concrete Flatwork 13
Earth Retaining Walls 14
Passive Pressure 14
Equivalent Fluid Pressure 14
Surcharge 14
Waterproofing and Subdrain Observation 14
Backfill 14
Limitations 14
Review, Obser\Tation and Testing. 14
Uniformity of Conditions : 15
Change in Scope 15
Time Limitations 15
Professional Standard 15
Client's Responsibility 16
Field Explorations 16
Laboratory Testing 17
ATTACHMENTS
TABLES
Table I Maximum Ground Acceleration, Page 5
Table II Seismic Design Parameters, Page 12
FIGURES
Figure 1 Site Vicinity Map, Follows Page 1
PLATES
Plate 1 Site Plan
Plates 2-7 Test Trench Logs
Plate 8 Su^ested Retaining WaU Subdrain Detail
APPENDICES
Appendix A References
Appendix B Recommended Grading Specifications - General Provisions
CWE 2040602.1
Proposed Residences
Cazadero Drive, Carlsbad, Califomia
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CHRISTIAN WHEELER
ENGINEERING
PRELIMINARY GEOTECHNICAL INVESTIGATION
PROPOSED RESIDENCES
2817-2819 CAZADERO DRPyE
CARI.SBAD. CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of a preliminary geotechnical investigation performed for the proposed
residences to be constructed on a previously graded lot located at 2817 and 2819 Cazadero Drive, in the La
Costa area of Carlsbad, California. Figure Number 1 presented on the following page provides a vicinity map
showing die location of the property.
The subject site is a vacant parcel of land located at 2817 and 2819 Cazadero Drive and is identified as
Assessor's Parcel Number 215-320-45. The lot has been graded into a relatively level pad that is about six feet
above Cazadero Drive. We understand that it is proposed to construct two, single-family residences on the lot
The proposed structure on the nordiwest portion of the site will be situated on the existing pad, two-stories in
height, and of wood-frame construction. Tlie proposed stmcture on the southeast portion of the site will have
split levels with two- and three-story portions, and will have a partially subterranean garage at the front with an
interior retaining wall. The above-grade portion of the stmcture will be of wood-frame construction while the
retaining portions are expected to consist of masonry block construction. Both sturctures will be supported by
conventional shallow spread footings and the lower floors will have on-grade concrete floor slabs. Grading is
expected to consist of cuts of about 12 feet from the existing grades and fills of about 5 feet from die existing
grades.
Tliis report has been prepared for the exclusive use of Cazadero Homes, Inc. and their design consultants for
specific application to the project described herein. Should the project be changed in any way, the modified
plans should be submitted to Christian Wheeler Engineering for re\tiew to determine their conformance with
our recommendations and to determine if any additional subsurface investigation, laboratory testing and/or
recommendations are necessary. Our professional services have been performed, our findings obtained and our
4925 Mercury Street ••• San Diego, CA 92111 • 858-496-9760 -•• FAX 858-496-9758
CWE 2040602.1 June 29, 2004 Page No. 2
recommendations prepared in accordance witli generally accepted engineering principles and practices. This
warranty is in lieu of all other warranties, express or implied.
PROJECT SCOPE
Our preliminarj' 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 strucmre, or any other services not specifically described in the scope of services presented below. More
specifically, the intent of this analysis was to:
a) Explore the subsurface conditions of the site to tlie depths influenced by the proposed
construction;
b) Evaluate, by laboratory tests and our experience, the engineering properties of the various strata
that may influence the proposed construction, including soil bearing capacities, expansive
characteristics and settiement potential;
c) Describe die general geology at the site including possible geologic hazards tiiat could have an
effect on die site construction, and provide the seismic design parameters required by the most
recent edition of the Uniform Building Code;
d) Address potential construction difficulties that may be encountered due to soil conditions,
groundwater, or geologic hazards, and provide recommendations conceming these condidons;
e) Develop soil-engineering criteria for the site preparation and grading, and address the stability of
cut and fill slopes;
f) Recommend an appropriate foundation system for the type of stmcmre anticipated and develop
soil engineering design criteria for the recommended foundation design;
g) Present our professional opinions diis written report that includes, in addition to our findings and
recommendations, a site plan showing the location of our subsurface explorations and a summary
of our laboratory test results.
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SITE VICINITY MAP
(Adapted from Thomas Brothers Maps)
PROPOSED RESIDENCES
2817-2819 CAZADERO DRIVE
CARLSBAD. CALIFORNIA
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North
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%^JJ*C —.A.ROH 1^ I -M'^ / if/
CWE 2040602.1 June 2004 Figure 1
CWE 2040602.1 June 29, 2004 Page No. 3
It is not within the scope of our services to perform laboratory tests to evaluate the chemical characteristics
of the on-site soils in regard to their potentially corrosive impact to on-grade concrete and below grade
improvements. If desired, we can submit representative soil samples to a chemical laboratory for analysis.
We suggest that such samples be obtained after grading is complete and the soils tiiat can affect concrete and
odier improvements are in place. Further, it should be understood Christian Wheeler Engineering does not
practice corrosion engineering. If such an analysis is necessary, we recommend that the developer retain an
engineering firm that specializes in this field to consult with them on this matter.
FINDINGS
SITE DESCRIPTION
The subject site is an irregular-shaped parcel of land located at 2817 and 2819 Cazadero Drive, in the La
Costa area of Carlsbad, California. Tlie subject site is identified as Assessor's Parcel Number 215-320-45, and
as Lot 306 of La Costa Meadows Unit No. 2 (Map 6905). The lot is vacant and has been graded to have a
relatively level pad in the western portion. An unimproved driveway along the north side of the lot provides
access to the pad. There is an approximately 6-foot-high fill slope at the front of the lot and a 12- to 15-foot-
high cut slope at die rear of the lot, at the base of a high, gendy ascending natural hillside. The lot is bounded
on the north and south by single-family residential properties. The lot has approximately 100 feet of firontage
along Cazadero Drive, ranges from approximately 215 to 225 feet in deptii, and has a rear propert)^ line length
of about 36 feet. On-site elevations range from a low of approximately 245 feet (MSL) in the west comer,
the grade of Cazadero Drive, to a high of approximately 269 feet (MSL), in the southeast corner of the site.
A few piles of constmction debris, gravel and cobble were found on the building pad. The building pad area is
relatively void of vegetation, wliile the upper, undismrbed portions of the site consist of relatively heavy
vegetation comprised of native bmsh.
GENERAL GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject property is located in tiie Footioills
Physiograpliic Province of San Diego County. Based upon the results of our limited exploration and analysis of
readily available, pertinent geologic and geotechnical literature, we have determined that die site is predominandy
underlain byJurassic-Cretaceous-age, undifferentiated Santiago Peak Volcanics that are overlain by man-placed
fiH materials in the westem portion and natural slopewash materials in the eastem portion. The soils encountered
during our subsurface explorations are described below in order of increasing age:
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CWE 2040602.1 June 29, 2004 Page No. 4
ARTIFICIAL FILL (Qaf): A layer of artificial fill was encountered in four of our five subsurface
explorations, Trenches T-l through T-4. The estimated limits of the existing fill are shown on the site
plan attached as Plate Number 1. In general, the existing fill material is limited to the westem portion of
die graded pad and die adjacent fill slope; however, a relatively thin layer of fill was noted in the eastem
portion of the graded pad. Witiiin Trench T-3, which was excavated at the westem edge of the graded
pad, the fill layer was found to have a thickness ranging from 6 feet at the west end of the trench to 2.5
feet at the east end. Within Trenches T-l, T-2, and T-4, the fill layer was only about six inches thick.
The fill material was found to generally consist of grayish- to medium-brown, silty sand (SM) that was
tj'pically damp to moist Within Trench T-3, die material was medium dense to dense in consistency.
Witliin the Trench T-l, T-2, and T-4, the material was generally loose in consistency. Based on our
observation of die fill layer exposed within Trench T-3, it appears that the fill was properly compacted
and properly benched into competent formational material. As such, the existing artificial fill material is
considered suitable in its present condirion to support settiement-sensitive improvements; however, the
upper portions will need to be scarified, moisture conditioned, and reconipacted in accordance with the
recommendations presented in the "Site Preparation" section of this report.
SLOPEWASH (Qsw): Altiiough not encountered within any of our exploratory trenches, this material
was visually obsen^ed in the existing cut slope within the eastem portion of the site. The slopewash
deposits consisted of medium to dark brown, silty sands (SM) tiiat were damp to moist and loose to
medium dense in consistency. There appeared to be as much as four feet of the slopewash above the
undifferentiated Santiago Peak Volcanics within the cut slope, but localized thicker deposits may exist
WEATHERED UNDIFFERENTIATED SANTIAGO PEAK VOLCANICS (KJsp): As well as
being visually lo^ed on a cut slope within the eastem portion of the site, Jurassic-Cretaceous-^e
materials identified as the undifferentiated Santiago Peak Volcanics were encountered within each of our
test trenches. The material comprising the Santiago Peak Volcanics consisted of reddish-brown to gray,
sandy gravel (GP). Tlie material was damp to moist and medium dense to dense in consistency. The
upper few feet of the formational material is moderately to highly firactured. These materials are
considered suitable in tiieir present condition to support fill and/or settiement-sensitive improvements.
GROUNDWATER: No groundwater was encountered in our explorations and we do not anticipate any
significant groundwater related problems during or after constmction provided that proper drainage is
maintained However, it should be recognized diat minor groundwater seepage conditions might occur after
development of a site even where none were present before development Tiiese are usually minor phenomena
and are often the result of an alteration in drainage pattems and/or an increase in irrigation water. Based on die
CWE 2040602.1 June 29, 2004 Page No. 5
pemieability characteristics of the soil and the anticipated usage and devdopment, it is our opinion diat any
seepage conditions, should diey de\'^dop, will be minor in extent. These potential "nuisance" conditions can
tj'pically be mitigated by the use of proper landscaping techniques.
TECTONIC SETTING: No faults are known to traverse die subject site. However, it should be noted tiiat
much of Southem California, including the San Diego County area, is characterized by a series of Quatemary-
age fault zones that consist of several individual, en echdon 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" according to the criteria of the Califomia Division of Mines and Geology. Active fault zones are
those that have shown conclusive evidence of faulting during the Holocene Epoch (die most recent 11,000
years).
A review of available geologic maps indicates that the active Rose Canyon Fault Zone is located
approximately 12 kilometers southwest of the subject site. Other active fault zones in the region that could
possibly affect the site indude the Coronado Bank and San Clemente Fault Zones to the southwest and the
Elsinore, Eartiiquake Valley, San Jacinto, and San Andreas Fault Zones to the northeast.
GEOLOGIC HAZARDS
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GROUND SHAKING: A likely geologic hazard to affect the site is ground shaking as a result of movement
along one of die major active fault zones mentioned above. The maximum ground accelerations that would be
attributed to a maximum magnitude earthquake occurring along the nearest fault segments of sdected fault zones
that could affect the site are summarized in the following Table I.
TABLE L MAXIMUM GROUND ACCELERATIONS
Fault Zone Distance Maximum Magnitude
Earthquake
Maximum Ground
Acceleration
Rose Canyon 12 km 6.9 magnitude 0.18 g
Newport-lnglewood 18 km 6.9 magnimde 0.13 g
Coronado Bank 36 km 7.4 magnitude 0.10 g
Elsinore 37 km 7.1 magnitude 0.07 g
Eartiiquake Valley 62 km 6.5 magnitude 0.04 g
San Jacinto 74 km 7.2 magnimde 0.05 g
CWE 2040602.1 June 29, 2004 Page No. 6
Probable ground shaking levels at die site could range from slight to moderate, depending on such factors as
die 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.
SURFACE RUPTURE: No active or potentially active faults are present at the subject site so the site is not
considered susceptible to surface mpture.
LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of diis investigation we reviewed die
publication, "Landslide Hazards in the Southem Part ofthe San Diego Metropolitan Area" by Tan, 1995. This
reference is a comprehensive study that dassifies San Diego County into areas of relative landslide susceptibility.
The subject site is located in Area 3-1. The Area 3-1 dassification is assigned to areas considered generally
susceptible to slope movement. Natural slopes within the Area 3-1 classification are considered at or near their
stability limits due to tiieir steep inclinations and can be expected to fail locally when adversely modified. Sites
witiiin this classification are located outside the boundaries of known landslides.
The site was found to be underlain, bdow the fill layer, by Undifferentiated Santiago Peak Volcanic Rock. Based
on our experience, tiiese materials typically have exceEent strengtii characteristics in terms of slope stability. As
such, it is our opinion that the potential for deep-seated landsliding on the subject site is low. In addition, it is our
opinion diat tiie potential for slope failures within the existing fill slope at the westem side of the subject site is
low. This is based on die proper compaction of the existing fill, the proper benching ofthe existing fill into
competent formational materials, and the inclination of the fill slope.
LIQUEFACTION: The near-surface soils encountered at the site are not considered susceptible to liquefaction
due to such factors as soil density, grain-size distribution and the absence of shallow groundwater conditions.
FLOODING: Based on our review of the maps prepared by the Federal Emergency Management Agency, the
site is located outside the boundary of the 100-year and 500-year floodplains.
TSUNAMIS: Tsunamis are great sea waves produced by submarine earthquakes or volcanic emptions. Due to
die devation of the site and its location, it should not be affected by a tsunami.
SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs.
Due to the site's location, it should not be affected by sdches.
CWE 2040602.1 June 29,2004 Page No. 7
CONCLUSIONS
No geotechnical conditions were found that would preclude the constmction of die proposed residential
project provided die recommendations presented in this report are followed. Based on our investigarion, we
have found that the site is underlain by artifidal fills and slopewash underlain by Cretaceous-age Santiago Peak
Volcanics. The Santiago Peak Volcanics encountered in our investigation are generally medium dense to dense
and suitable to support the proposed constmction. The existing artifidal fiU material appears to have been
properly compacted and properly benched into competent formational material and is, therefore, considered
suitable in its present condition to support settiement-sensitive improvements; however, the upper portions will
need to be scarified, moisture conditioned, and recompacted. The existing slopewash material is considered
unsuitable in its present condition to support settiement-sensitive improvements. As such, the slopewash
that is not removed by planned grading, will need to be removed and be replaced as properly compacted fill
material. In addition, it appears that the front residence will be traversed by a cut/fill transition. Where this
occurs, it will be necessary to undercut the cut portion of the building pad. This being accomplished, the
proposed residences can be supported by conventional spread foundations and with conventional concrete
slabs-on-grade.
No geologic hazards of sufficient magnitude to preclude development of the site as we presendy contemplate
it are known to exist In our professional opinion and to the best of our knowledge, the site is suitable from a
geologic perspective for the proposed constmction, provided the stmcmre is designed in accordance with the
requirements of the most recent edition of the Uniform Building Code and the local govemmental agencies.
RECOMMENDATIONS
GRADING AND EARTHWORK
GENERAL: All grading should conform to the guidelines presented in Appendix Chapter A33 of the
Uniform Building Code, die minimum requirements of the City of Carlsbad, and the Recommended Grading
Spedfications and Special Provisions attached hereto as Appendix B, except where specifically superseded in
the text of diis report Prior to grading, a representative of Christian Wheeler Engineering should be present
at the preconstruction meeting to provide additional grading guidelines, if necessary, and to review the
earthwork schedule.
OBSERVATION OF GRADING: Continuous observation by the Geotechnical Consultant is essential
during the grading operation to confirm conditions anticipated by our investigation, to allow adjustments in
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CWE 2040602.1 June 29, 2004 Page No. 8
design criteria to reflect actual fidd conditions exposed, and to determine that the grading proceeds in general
accordance with the recommendations contained herein.
CLEARING AND GRUBBING: At tiie time of our site investigation, the existing building pad was deared
of vegetation, but did support some construction debris. The site preparation should begin with the removal of
the constmction debris and any vegetation and other deleterious materials from the portions of site that will be
graded and/or will recdve improvements. The resulting materials should be disposed of off-site.
SITE PREPARATION: After clearing and gmbbing, the existing slopewash material should be removed
from the areas to recdve fill or settiement-sensitive improvements to the contact with underlying materials of
the Santiago Peak Volcanics. Based on our limited subsurface explorations, the existing slopewash deposits are
expected to have an approximate thickness of four feet, but may be thicker in localized areas. The removals
should extend laterally at least five feet outside the building perimeter and at least two feet outside Ught exterior
improvements. No otiier special site preparation is considered necessary at diis time.
BUILDING PAD UNDERCUTS: It appears tiiat the front residence will be traversed by a cut/fill transition.
Wliere tiiis occurs, die cut portion of the building pad should be undercut at least tiiree feet below finish grade.
In addition, tiie excavation for the partially subterranean garage may expose very dense hardrock that cannot be
excavated with light trenching equipment If this is the case, consideration should be given to undercutting the
building pad and utility alleys to at least six inches bdow the bottom of the foundations and utilities and
replacing the excavated material with compacted fill material.
The bottom of all overexcavated areas should be sloped in such a manner that water does not become trapped
in the overexcavated zone. Prior to replacing the excavated materials, the soils exposed at the bottom of the
excavation should be scarified to depth of six inches, moismre conditioned and compacted to at least 90 percent
relative compaction.
PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constmcting any new improvements
in areas that have been cleaned out and approved to recdve fill, the exposed soils should be scarified to a depth
of 12 inches, moisture conditioned, and compacted to at least 90 percent relative compaction. No other spedal
ground preparation is antidpated at this time.
COMPACTION AND METHOD OF FILLING: AR stmctural fill placed at tiie site should be compacted
to a relative compaction of at least 90 percent of its ma.ximum dry density as determined by ASTNl Laboratory
H Test Dl 557-91. FiUs should be placed at or sUghtiy above optimum moisture content, in lifts six to eight inches
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CWE 2040602.1 June 29, 2004 Page No. 9
thick, witii each lift compacted by mechanical means. Fills should consist of approved eartii material, firee of
trash or debris, roots, vegetation, or otiier materials determined to be unsuitable by our soil technicians or
project geologist Fill material should be free of rocks or lumps of soil in excess of twelve inches in maximum
dimension. However, in die upper two feet of pad grade, no rocks or lumps of soil in excess of six inches
should be allowed.
The proposed fiUs should be benched at least two feet into all temporary slopes and into competent natural
or existing fill soils when the existing slope is steeper than an inclination of 5:1 (horizontal to vertical). A key
should be constmcted at die toe of tiie proposed fill slope. The key should extend at least 12 inches into firm
natural ground and should be sloped back at least two percent into the slope area. The key should have a
minimum width of 5 feet
Utility trench backfiU within five feet of the proposed stmcmres and beneath all pavements and concrete
flatwork should be compacted to a minimum of 90 percent of its maximum dry density.
CUT AND FILL SLOPE CONSTRUCTION: Proposed cut and fill slopes wiU have a maximum height
of about 10 feet and are to be constmcted at an inclination of 2:1 or flatter (horizontal to vertical). Care
should be taken to make sure that highly expansive materials are not placed within five feet of the face of the
fill slope. Compaction of die slope should be performed by back-rolling with a sheepsfoot compactor at
vertical intervals of four feet or less as the fill is being placed, and track-walking the face of the slope when
the slope is completed. As an alternative, the fill slopes may be overfilled by at least three feet and then cut
back to the compacted core at the design line and grade. Keys should be made at the toe of fill slopes in
accordance with die recommendations presented above under "Compaction and Method of Filling".
SURFACE DRAINAGE: Surface mnoff into graded areas should be minimized. Where possible, drainage
should be directed to suitable disposal areas via non-erodible devices such as paved swales, gumted brow
ditches, and storm drains. Pad drainage should be designed to collect and direct surface water away from
proposed stmctures and die top of slopes and toward approved drainage areas. For earth areas, a minimum
gradient of one percent should be maintained.
The ground around the proposed buildings should be graded so that surface water flows rapidly away from
the buildings witiiout ponding. In general, we recommend that the ground adjacent to the building slopes
away at a gradient of at least two percent. Densely vegetated areas where mnoff can be impaired should have
a minimum gradient of five percent within the first five feet from tiie stmcture. Gutters and downspouts
should discharge to controlled drainage systems.
CWE 2040602.1 June 29, 2004 Page No. 10
TEMPORARY CUT SLOPES: Temporary cut slopes of up to 12 feet in height are anticipated to be
required during the proposed constmction. Ttmpoiziy cut slopes of up to twelve feet in hdght, for retaining
walls, can be excavated vertical for the bottom five feet and at an inclination of 0.5 to 1.0 (horizontal to
vertical) or flatter above. All temporary cut slopes should be observed by the engineering geologist during
grading to ascertain that no unforeseen adverse conditions exist. No surcharge loads such as soil or
equipment stockpiles, vehides, etc. should be allowed within a distance from the top of temporary slopes
equal to half the slope height Where there is not room to constmct temporary slopes, temporary shoring of
the excavation sides may be necessary.
The contractor is solely responsible for designing and constmcting stable, temporary excavations and may
need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the
excavation sides. The contractor's "responsible person", as defined in the OSHA Constmction Standards
for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the
contractor's safety process. Temporary cut slopes should be constmcted in accordance with the
recommendations presented in this section. In no other case should slope height, slope inclination, or
excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal
safety iegulations.
SLOPE STABILITY
GENERAL: All slopes at tiie subject site ^vill be constmcted at a slope ratio of 2:0 horizontal units to 1.0
vertical unit (2:1) or flatter, with a maximum height of about 10 feet Based on the relatively high strength
parameters of tiie on-site soils in their natural and compacted states, it is our opinion that the proposed slopes
will be stable in regards to deep-seated slope failure and surficial slope failure. Provided the slope is constmcted
in accordance with die above recommendations, it is our opinion that the proposed slope will have a factor of
safet}' against failure in excess of the normally required minimum safety factor of 1.5.
EROSION CONTROL: The placement of cohesionless soils at the face of slopes should be avoided. Slopes
should be planted as soon as feasible after grading. Sloughing, deep rilling and slumping of surfidal soils may be
anticipated if slopes are left unplanted for a long period of time, espedally during die rainy season. Irrigation of
slopes should be carefiilly monitored to insure that only die minimum amount necessary to sustain plant life is
used. Over-irrigating could be extremely erosive and should be avoided.
C\X^ 2040602.1 June 29, 2004 Page No. 11.
FOUNDATIONS
GENERAL: Based on our findings and engineering judgments, it is our opinion that the proposed residences
may be supported by shallow conventional contiriuous and isolated spread footings. The following
recommendations are considered die minimum based on soil conditions and are not intended to be lieu of
stmctural considerations. All foundations should be designed by a qualified stmctural engineer.
FOUNDATION DIMENSIONS: Spread footings supporting die proposed two- and three-story stmctures
should be embedded at least 18 and 24 inches bdow finish pad grade, respectively. Retaining wall footings
should be embedded at least 18 inches bdow finish grade. Continuous should have a minimum width of 15
inches and 18 inches for two- and three-story constmction, respectively. Continuous footings supporting
retaining walls and isolated footings should have a minimum width of 24 inches.
BEARING CAPACITY: Conventional continuous spread footings with the above minimum dimensions for
Kvo-stor)' stmctures may be designed for an allowable soil bearing pressure of 3,500 pounds per square foot
Tliis value may be increased by 300 and 700 psf for each addition foot of footing width and embedment,
respectively, to a maximum of 5,000 psf This value may also be increased by one-third for combinations of
temporary loads such as diose due to wind or sdsmic loads.
FOOTING REINFORCEMENT: The project stmctural engineer should provide reinforcement
requirements for foundations. However, based on soil conditions, we recommend that the minimum
reinforcing for continuous footings consist of at least two No. 5 bars positioned three inches above the bottom
of die footing and two No. 5 bars positioned two inches below 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 die footing. The coeffident
of friction between concrete and soil may be considered to be and 0.35. The passive resistance may be
considered to be equal to an equivalent fluid weight of 350 pounds per cubic foot This assumes the footings are
poured tight against undisturbed soil. If a combination of the passive pressure and friction is used, the friction
value should be reduced by one-third.
SETTLEMENT CHARACTERISTICS: Tlie antidpated total and differential settiement is expected to be
less dian about one inch and one inch in forty feet, respectively, provided the recommendations presented in
this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and
C^VE 2040602.1 June 29, 2004 Page No. 12
foundations due to shrinkage during concrete curing or redistribution of stresses, therefore some cracks
should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements.
FOUNDATION PLAN REVIEW: Tlie foundation plans should be submitted to diis office for review in
order to ascertain diat die recommendations of this report have been implemented, and that no additional
recommendations are needed due to changes in the anticipated constraction.
FOUNDATION EXCAVATION OBSERVATION: All foundation excavations should be observed by die
Geotechnical Consultant prior to placing reinforcing steel or formwork to determine if the foundation
recommendations presented herein are followed. All footing excavations should be excavated neat, levd, and
square. All loose or unsuitable material should be removed prior to the placement of concrete.
SEISMIC DESIGN PARAMETERS: Based on a maximum magnimde (Mmax) eartiiquake of 6.9 along
the nearest portion of the Rose Canyon Fault Zone, the Maximum Ground Acceleration at the site would be
approximately 0.18 g. For stmctural design purposes, a damping ratio not greater than 5 percent of critical
dampening, and Soil Profile Type SB are recommended (UBC Table 16-J). Based upon the location of the
site being greater than 10 kilometers from the Rose Canyon Fault (Type B Fault), Near Source Factors N»
equal to 1.0 and Nv equal to 1.0 are also applicable. These values, along with other seismically related design
parameters from the Uniform Building Code (UBC) 1997 edition, Volvime II, Chapter 16, utilizing a Sdsmic
Zone 4 are presented in the following table.
TABLE II: SEISMIC DESIGN PARAMETERS
UBC - Chapter 16
Table No.
Seismic
Parameter
Recommended
Value
16-1 Seismic Zone Factor Z 0.40
16-J Soil Profile Type SB
16-Q Seismic Coeffident C, 0.40 N,
16-R Sdsmic Coeffident Cv 0.40 Nv
16-S Near Source Factor Na 1.0
16-T Near Source Factor Ny 1.0
16-U Seismic Source Type B
CWE 2040602.1 June 29, 2004 Page No. 13
ON-GRADE SLABS
GENERAL: It is our understanding that die proposed residences will use concrete slabs-on-grade. The
foUowing recommendations assume tiiat the subgrade soils have been prepared in accordance with the
recommendations presented in the "Site Preparation" section of this report. In addition, the following
recommendations are considered to be the minimum slab requirements based on the soil conditions and are
not intended to be in lieu of stmctural considerations. All slabs should be designed by a qualified stmctural
engineer.
INTERIOR FLOOR SLABS: The minimum floor slab diickness should be four inches (actual) and all
floor slabs should be reinforced with at least No. 3 rdnfordng bars placed at 18 inches on center each way.
Slab reinforcement should be supported on chairs such diat die rdnfordng bars are positioned at mid-hdght
in the floor slab. The garage slab may be constmcted independent of the garage perimeter footings.
However, if die garage slab and footings are poured monolithically, the slab rdnforcement should extend into
the perimeter foundations at least six inches.
MOISTURE PROTECTION FOR INTERIOR SLABS: It should be noted diat it is die industry
standard that interior on-grade concrete slabs be underlain by a moisture retarder. We suggest tiiat dhe
subslab moistore retarder consist of at least a two-inch-thick blanket of one-quarter-inch pea gravel or dean
coarse sand overlain by a layer of 10-mil visqueen. The visqueen should be overlain by a two-inch-tiiick layer
of coarse, clean sand that has less than ten percent and five percent passing die No. 100 and No. 200 sieves.
Our e.xperience indicates that this moisture barrier should allow die transmission of firom about six to twdve
pounds of moisture per 1000 square feet per day through the on-grade slab. This may be an excess amount of
moisture for some types of floor covering. If additional protection is considered necessary, die concrete mix
can be designed to help reduce the permeability of the concrete and thus moismre emission upwards through
the floor slab.
EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of four inches.
Reinforcement and control joints should be constmcted in exterior concrete flatwork to reduce the potential for
cracking and movement Joints should be placed in exterior concrete flatwork to help control the location of
shrinkage cracks. Spacing of control joints should be in accordance with the American Concrete Institute
spedfications. When patio, walks and porch slabs abut perimeter foundations they should be doweled into the
footings.
I
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CWE 2040602.1 June 29, 2004 Page No. 14
EARTH RETAINING WALLS
PASSIVE PRESSURE: Tlie passive pressure for the prevailing soil conditions may be considered to be 350
pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The
coefficient of friction for concrete to soil may be assumed to be 0.35 for the resistance to lateral movement.
When combining frictional and passive resistance, the friction should be reduced by one-third. The upper 12
inches of exterior retaining wall footings should not be included in passive pressure calculations where
abutted by landscaped or unpaved areas.
EQUIVALENT FLUID PRESSURE: The active soil pressure for die design of "unrestrained" and
"restrained" earth retaining stmctures with level backfill may be assumed to be equivalent to the pressure of a
fluid weighing 35 and 55 pounds per cubic foot, respectively. These values assimie a drained backfill
condition.
SURCHARGE: No surcharge loads have been considered. If any surcharge loads are anticipated, this
office should be contacted for the necessary increase in lateral soil pressures.
WATERPROOFING AND SUBDRAIN OBSERVATION: The project architect should provide
waterproofing details. The geotechnical engineer should be requested to verify that waterproofing has been
applied. A suggested wall subdrain detail is provided on the attached Plate Number 8. We recommend that
the Geotechnical Consultant be retained to observe all retaining wall subdrains to verify proper constmction.
BACKFILL: All backfill soils should be compacted to at least 90 percent relative compaction. 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 die Geotechnical Consultant and
engineering geologist so that they may review and verify their compliance with this report and with the
Uniform Building Code.
CWE 2040602.1 June 29, 2004 Page No. 15
It is recommended diat Christian Wheeler Engineering be retained to provide continuous soil engineering
services during die eartiiwork operations. This is to verify compliance with the design concepts, spedfications
or recommendations and to allow design changes in the event tiiat subsurface conditions differ from those
antidpated prior to start of constmction.
UNIFORMITY OF CONDITIONS
The recommendations and opinions expressed in this report reflect our best estimate of the project
requirements based on an evaluation of die subsurface soil conditions encountered at the subsurface
e-xploration locations and on the assumption that the soil conditions do not deviate appreciably from those
encountered. It should be recognized that die performance of the foundations or temporary slopes might be
influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate
and une.xplored 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 Consultant so that he may make
modifications if necessary.
CFLySIGE IN SCOPE
Tliis 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. Tliis should be verified in writing or
modified by a written addendum.
TIME LIMITATIONS
Tlie 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 die 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 reKed upon after a period of two years without a review by us
verifying the suitabilit)' 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 currendy practidng under similar conditions and in the same locality.
CWE 2040602.1 June 29, 2004 Page No. 16
The client recognizes that subsurface conditions may vary firom those encountered at the locations where our
borings, sun^eys, 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 diose 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 onfy, 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 fiimishing of oral or written
reports or findings.
CLIENT'S RESPONSIBIUTY
It is the responsibilit)' of the Client, or their representatives to ensure that the information and
recommendations contained herein are brought to the attention of the stmcmral engineer and arcliitect 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 liis subcontractors carry out such recommendations
during constmction.
FIELD EXPLORATIONS
Six subsurface explorations were made at the locations indicated on the site plan induded herewith as Plate
Number 1 on January 23, 2003. These explorations consisted of six test trenches using a Case 580L Backhoe.
The fieldwork was conducted under die observation and direction of our engineering geology personnel.
Tlie explorations were carefully logged when made. The test trench logs are presented on the following Plate
Numbers 2 through 7. The soils are described in accordance with the Unified Soils Classification. In addition, a
verbal texmral description, the wet color, the apparent moisture and the density or consistency are 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.
Disturbed "bulk" samples and rdatively undisturbed "chunk" samples were taken from die trench excavations
and transported to our laboratory for testing.
CWE 2040602.1 June 29, 2004 Page No. 17
LABORATORY TESTING
Laboratory tests were performed in accordance with the generaUy accepted American Sodety for Testing and
Materials (ASTM) test metiiods or suggested procedures. A brief description of the tests performed is
presented bdow.
a) CLASSIFICATION: Field dassifications were verified in the laboratory by visual examination. The
final soil classifications are in accordance with the Unified Soil Classification System.
b) MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for
representative soil samples. This information was an aid to classification and permitted recogmtion of
variations in material consistency with depth. The dry unit wdght is determined in pounds per cubic
foot, and the in-place moismre content is determined as a percentage of the soil's dry weight. The
results of diese tests are summarized in the boring logs.
c) COMPACTION TEST: The maximum dry density and optimum moisture content of typical soils
were determined in die laboratory in accordance with ASTM Standard Test D-1557-91. The result of
this test is presented below.
Sample Numben Trench T-3 @ 0 - 3'
Sample Description: Light yellowish-brown, silty sand (SM)
Optimum Moisture Content 10.7 %
Maximum Density: 119.0 pcf
d) DIRECT SHEAR TEST: A direct shear test was performed to determine the failure envdope of
the anticipated foundation soils based on yidd shear strength. The shear box was designed to
accommodate a sample having a diameter of 2.375 inches or 2.50 inches and a hdght of 1.0 inch.
The sample was tested at different vertical loads and at a saturated moisture content The shear stress
was appUed at a constant rate of strain of approximately 0.05 inch per minute. The results of these
tests are presented below.
Sample Number: Trench T-3 @ 0 - 3'
Sample Type: Remolded to 90 %
Angle of Intemal Friction: 26°
Apparent Cohesion: 300 psf
CWE 2040602.1 June 29, 2004 Page No. 18
e) GRAIN SIZE DISTRUBUTION: Tlie grain size distribution of a selected sample was
detemiined in accordance witii ASTM D422. Tlie results of these tests are presented below.
Sample Location Trench T-3 @0-
Sieve Size Percent Passing
#4 100
#8 99
#16 97
#30 95
#50 90
#100 62
#200 35
Soil Type SM
I
- 2
Date Excavated:
Equipment:
Existing Elevation:
Finish Elevation:
LOG OF TEST TRENCH NUMBER T-l
1/23/2003 Logged by
Case 580 Backhoe
464 feet
466 feet
TSW
Project Manager CHC
Depdi to Water: N/A
Drive Weight: N/A
5
Q
- 3
- 4
- 5
- 7
- 8
- 9
LlO
o
u I—I
X SUMMARY OF SUBSURFACE CONDITIONS
Artificial FiU (Oaf): Grayish-brown, moist, loose, GRiWTELLY
^ ^_ .,SAND(SM).
Weathered Undifferentiated Santiago Peak Volcanics (KJsp):
Reddish-brown and gray, damp to moist, medium dense to dense,
S.\NDY GR.W'EL (GP), moderately to highly fractured.
Practical refusal at 4 feet.
SAMPLES
CK
o
H
w o
4.5
Q
142.7
CHRIST1.\N-WHEELER
E N C. I N E F. K 1 N G
PROPOSED LA COSTA DUPLEX
2817 & 2819 Cazadero Dr., Carlsbad, Califomia
CHRIST1.\N-WHEELER
E N C. I N E F. K 1 N G
BY: HF DATE: Febmarj' 2003 CHRIST1.\N-WHEELER
E N C. I N E F. K 1 N G JOB NO.: 2040602 PL.\TE NO.: 2
LOG OF TEST TRENCH NUMBER T-2
Date Excavated:
Equipment:
Existing Elevation:
Finish Elevation:
1/23/2003
Case 580 Backhoe
464 feet
466 feet
Logged by: TSW
Project Manager CHC
Depdi to Water: N/A
Drive Weight: N/A
X H
a
- 4
- 5
- 7
- 9
LlO
o
I-l u
X
o
SUMNL\RY OF SUBSURFACE CONDITIONS
Artificial Fill (Oaf>: Grapsh-brown, moist, loose, SILTi' SAND (SjVI).
Weathered Undifferentiated Santiago Peak Volcanics (KJsp):
Reddish-brown and gray, damp to moist, medium dense to dense,
SANDY GRW^EL (GP).
Moderately to highly fractured from Vi to 2'/a feet.
At 2V2 feet becomes dense to verv dense.
Practical refiisal at 3V2 feet
SAMPLES
CK
o
[13 o
z e
PH
D H
CO
H-1
o
8..-i
Q
152.1
CHRISTIAN WHEELER
ENCIN 1-: F. R 1 N G
PROPOSED LA COSTA DUPLEX
2817 & 2819 Cazadero Dr., Carlsbad, Califomia
CHRISTIAN WHEELER
ENCIN 1-: F. R 1 N G
BY: HF DATE: Febmar>' 2003 CHRISTIAN WHEELER
ENCIN 1-: F. R 1 N G JOB NO.: 2040602 PL\TENO.: 3
i
Date Excavated:
Equipment:
Existing Elevation:
Finish Elevation:
LOG OF TEST TRENCH NUMBER T-3
1/23/2003 Logged by
Case 580 Backhoe
464 feet
457.5 feet
TSW
Project Manager CHC
Depdi to Water N/A
Drive Weight: N/A
X H
PH
W
Q
O
O
U
HH
X
PH
o
SUMMARY OF SUBSURFACE CONDITIONS
S.•^M]'LHS
D H on
HH
Q
- 1
Artificial Fill (Oaf); Light gray, moist, medium dense to dense, SILT^'
SAND (SM), very fine to fine-grained.
12.6 109.8
MD
DS
- 4
- 5
- 7
- 9
LlO
Medium brown, damp to moist, medium dense to dense, SILTY
SAND (SiNJ), with gravd and clay.
CK
Weathered Undifferentiated Santiago Peak Volcanics (KJsp):
Reddish-brown and gray, damp to moist, dense, SANDY
^ GILW^L (GP). Highly fractured from 6-7 feet. Becomes ver\- dense at 7'.j
Practical refusal at 7 feet
7.2 10.3.6
CHRISTIAN WHEELER
UNGINEEIIING
PROPOSED LA COSTA DUPLEX
2817 & 2819 Cazadero Dr., Carlsbad, California
BY': HF
JOB NO.: 2040602
DATE: Febmar)' 2003
PL.\TE NO.:
i
I
I
I
I
I
I
I
Date Excavated:
Equipmenfc
Existing Elevation:
Finish Elevation:
LOG OF TEST TRENCH NUMBER T-4
1/23/2003 Logged by: TSW
Case 580 Backhoe Project Manager CHC
464 feet Depth to Water N/A
466 feet Drive Weight: N/A
X H
[i3
P
- 1
- 2
- 3
- 4
- 5
- 7
- 8
- 9
LlO
o
o
I-l u I—I
X
PH
O
SUMNL\RY OF SUBSURFACE CONDITIONS
Artificial Fill (Qaf): Grapsh-brown, moist, loose, GIL\^TLLY
,SAND(SM).
Weathered Undifferentiated Santiago Peak Volcanics (KJsp):
Reddish-brown and gray, damp to moist, medium dense to dense,
SANDY GR\\TEL (GP). At 3 feet becomes dense to very dense.
From 'A to 3 feet becomes moderately to highly fractured.
Practical refusal at 3V2 feet
S,\i\IPLES
I
<;
00
CK
z
H ^ Dd .2
Z &
PH
D H c/i
o
0.8
§ PH
Q
16.V4
m
CHKISTI.AN WHEELER
i; N G 1 N E E R. 1 N G
PROPOSED LA COSTA DUPLEX
2817 & 2819 Cazadero Dr., Carlsbad, Califomia m
CHKISTI.AN WHEELER
i; N G 1 N E E R. 1 N G
BY: HF DATE: Februar)' 2003
m
CHKISTI.AN WHEELER
i; N G 1 N E E R. 1 N G JOB NO.: 2040602 PL\TE NO.: 5
i
I
I
i
Date Excavated:
Equipment
Existing Elevation:
Finish Elevation:
LOG OF TEST TRENCH NUMBER T-5
1/23/2003 Logged by
Case 580 Backlioe
464 feet
N/A
TSW
Project Manager CHC
Depth to Water: N/A
Drive Weight: N/A
5
PH
P
- 3
- 4
- 5
- 7
- 8
- 9
LlO
a o
u
X p-
o
SUMMARY OF SUBSURFACE CONDITIONS
Weathered Undifferentiated Santiago Peak Volcanics (KJsp);
Reddish-brown and gray, damp to moist, dense, SANDY'
GR\VEL (GP).
Moderately to highly fractured from 0-12 inches.
At 12 inches becomes very dense.
Practical refusal at 2V2 feet
SAMPLES
z o
tsi ° z e a
PH
o P
00 H
00
CHRISTIAN WHEELER
K N G I N E L R I N G
PROPOSED LA COSTA DUPLEX
2817 & 2819 Cazadero Dr., Carlsbad, Califomia
BY: HF
JOB NO.: 2040602
D.\TE: February2003
PLATE NO.:
Date Excavated:
Equipment:
Existing Elevation:
Fimsh Elevation:
LOG OF TEST TRENCH NUMBER T-6
1/23/2003 Logged by: TSW
Case 580 Backhoe Project Manager CHC
474.0 feet Depth to Water N/A
476.0 feet Drive Wdght: N/A
X H
PH
p
o o
•-1
u
•—I
X
PH
SUMMARY OF SUBSURFACE CONDITIONS
S.'\MPLiiS
Z
o ^
W .2
PH
D
I-H
o P
O H
2
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
LlO
Slopewash (Osw); Medium to dark brown, damp to moist, loose to
medivim dense, SILTY' SAND (SM), with gravel.
Weathered Undifferentiated Santiago Peak Volcanics (KJsp);
Reddish-brown and gray, damp to moist, medium dense to dense,
SANDY GRW^ (GP).
Moderately to highly fractured from 4-7 feet
Dense to veiy dense at 7 feet
Test trench terminated at 10 feet
CHRISTIAN WHEELER
ENGINEERING
PROPOSED LA COSTA DUPLEX
2817 & 2819 Cazadero Dr., Carlsbad, Califomia
CHRISTIAN WHEELER
ENGINEERING
BY: HF DATE: Febmar)' 2003 CHRISTIAN WHEELER
ENGINEERING JOB NO.: 2040602 PLATE NO.: 7
6-inch Miniinum
3/4 inch Cmshed Rock or
Miradrain 6000 or Equivalent Waterproof Back of WaU
Per Arcliitect's Specifications
Top of Ground
or Concrete Slab
Geofabric Between
Rock and Soil
T 6-inch
Minimum
Minimum
4-inch Diameter
Perforated Pipe
PVC Schedule 40
RETAINING WALL
SUBDRAIN DETAIL
No Scale
CHRISTIAN WHEELER
. i ; N G I N n E R. 1 N G
•t'-'^s Mi-Rc:LM{YS'niEi.n'
S.'\N DIHGC), C.-\J.II-ORNIA rail
•I'EL. (K58) 49(,-'mo
l-AX. («58) 469-9758
PROPOSED RESIDENCES
2817-2819 CAZADERO DRIVE, CARLSBAD, CALIFORNLV
BY: SI IV
JOB NO.: 2040602
DATE: June 2004
PL VTE NO.:
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r
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CWE 2040602.1 June 29, 2004 Appendix A, Page Al
REFERENCES
Christian Wheeler Engmeering, Febmary 17,2003, Report of Preliminary Geotechtiical Investigation. Proposed
Residential Duplex. 2817-2819 Cazadero Drive. Carlsbad. CaUfomia.
Anderson, J.G.; Rockwell, R.K. and Agnew, D.C, 1989, Past and Possible Future Earthquakes of Significance
to die San Diego Region, Earthquake Spectra. Volume 5, No. 2,1989.
Blake, T.F., 2000, EQFAULT, A Computer Program for the Estimation of Peak Horizontal Acceleration firom
3-D Fault Sources, Version 3.0, Tliomas F. Blake Computer Services and Software, Thousand Oaks, Califomia.
Boore, David M., Joyner, WilUam B., and Fumal, Thomas E., 1997, "Empirical Near-Source Attenuation
Relationsliips for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Ground Velodty,
and Pseudo-Absolute Acceleration Response Spectra", in Sdsmological Research Letters, Volume 68, Number
LJanuary/Febmary 1997.
CaUfomia Division of Mines and Geology, 1998, Maps of Known Active Fault Near Source-Zones in CaUfomia
and Adjacent Portions of Nevada.
Federal Emergency Management Agency, 1997, San Diego County, CaUfomia and Incorporated Areas Ho6d
Insurance Rate Map, Pand 1051 of 2375, Map Number 06073C1051 F.
Hart, E.W., 1994, Fault-Rupture Hazard Zones in CaUfomia, CaUfomia Division of Mines and Geology Spedal
PubUcation 42.
Jennings, C.W., 1975, Fault Map of CaUfomia, CaUfomia Division of Mines and Geology, Map
No. 1, Scale 1:750,000.
Kem, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp.
Tan, S.S., 1995, LandsUde Hazards in the Northem Part of the San Diego MetropoUtan Area, San
Diego County, CaUfornia, CaUfornia Division of Mines and Geology Open-File Report 95-04.
Tan, Siang S. and Kennedy, Michael P., 1996, Geologic Maps of the Northwestem Part of San Diego County,
CaUfomia, CaUfomia Division of Mines and Geology, DMG Open-File Report 96-02.
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CWE 2040602.1 June 29, 2004 Appendix A, Page A2
Wesnousky, S.G., 1986, "Eardiquakes, Quaternary Faults, and Seismic Hazards in CaUfomia", in
Joumal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November 1986.
TOPOGRAPHIC MAPS
County of San Diego, 1960, Map Sheet 342-1695; Scale: 1 inch = 200 feet
County of San Diego, 1975, Map Sheet 342-1695; Scale: 1 inch = 200 feet.
CWE 2040602.1 June 29, 2004 Appendix B, B-1
RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS
PROPOSED RESIDENCES
2817 AND 2819 CAZADERO DRIVB
CARLSBAD. CALIFORNL\
GENERAL INTENT
The intent of these spedfications is to estabUsh procedures for clearing, compacting natural ground,
preparing areas to be fiUed, 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 Spedfications and shaU supersede
die provisions contained herdnafter 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
wdl be allowed, except where spedfied in the geotechrucal report or in other written communication signed
by the Geotechnical Engineer.
OBSERVATION AND TESTING
Christian Wheeler Engineering shaU be retained as the Geotechnical Engineer to observe and test the
earthwork in accordance with these specifications. It will be necessary that the Geotechiucal Engineer or his
representative provide adequate observation so that he may provide his opinion as to whether or not the
work was accompUshed as specified. It shall be the responsibiUty of die 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 opiruons. 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
shaU be contacted for further recommendations.
If, in the opinion ofthe Geotechnical Engineer, substandard conditions are encountered, such as
questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc.,
constmction should be stopped until the conditions are remedied or corrected or he shaU recommend
rejection of this work.
Tests used to detemiine the degree of compaction should be performed in accordance with the foUowing
American Sodety for Testing and Materials test methods:
CWE 2040602.1 June 29, 2004 Appendix B, B-2
Ma.ximum Density & Optimum Moisture Content - ASTM D-1557-91
Density of Sod In-Place - ASTM D-1556-90 or ASTM D-2922
AU densities shaU be expressed in terms of Rdative Compaction as determined by the foregoing ASTM
testing procedures.
PREPARATION OF AREAS TO RECEIVE FILL
AU vegetation, bmsh and debris derived from clearing operations shaU be removed, and legaUy disposed of.
AU areas disturbed by site grading should be left in a neat and finished appearance, free from unsighdy debris.
After clearing or benching the natural ground, the areas to be fiUed shaU be scarified to a depth of 6 inches,
brought to the proper moisture content, compacted and tested for the specified minimum degree of
compaction. AU loose soUs in excess of 6 inches thick should be removed to firm natural ground which is
defined as natural soil which possesses an in-sim density of at least 90 percent of its maximum dry density.
Wlien the slope of the natural ground receiving fiU exceeds 20 percent (5 horizontal units to 1 vertical unit),
the original ground shaU be stepped or benched. Benches shaU be cut to a firm competent formational sod.
The lower bench shaU be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and
shaU be sloped back into the hdlside at a gradient of not less tiian two (2) percent AU other benches should
be at least 6 feet wide. The horizontal portion of each bench shaU be compacted prior to recdving fiU as
specified herein for compacted natural ground. Ground slopes flatter than 20 percent shaU be benched when
considered necessary by the Geotechnical Engineer.
Any abandoned buried structures encountered during grading operations must be totaUy removed. AU
underground utiUties to be abandoned beneath any proposed stmcture should be removed from within 10
feet of the stmcture and properly capped off. The resulting depressions from the above described procedure
should be backfiUed with acceptable soil that is compacted to the requirements of the Geotechnical Engineer.
Tliis includes, but is not Umited to, septic tanks, fuel tanks, sewer Unes or leach Unes, storm drains and water
Unes. Any buried stmcmres or utiUties not to be abandoned should be brought to the attention of the
Geotechnical Engineer so that he may determine if any spedal recommendation wiU be necessary.
AU water weUs which wiU be abandoned should be backfiUed 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
i CWE 2040602.1 June 29, 2004 AppendLx B, B-3
feet below the bottom of footing whichever is greater. The type of cap wiU depend on the diameter of the
weU and should be determined by the Geotechnical Engineer and/or a quaUfied Stmcmral Engineer.
FILL MATERIAL
Materials to be placed in the fiU shaU be approved by the Geotechrucal Engineer and shaU be free of
vegetable matter and other deleterious substances. Granular soil shaU contain sufficient fme material to fiU
the voids. The definition and disposition of oversized rocks and expansive or detrimental sods are covered
in the geotechnical report or Spedal Provisions. Expansive soils, soils of poor gradation, or soils with low
strength characteristics may be thoroughly mixed with other soils to provide satisfactory fiU material, but oidy
with the expUcit consent of the Geotechiucal Engineer. Any import material shaU be approved by the
Geotechnical Engineer before bdng brought to the site.
PLACING AND COMPACTION OF FILL
Approved fiU material shaU be placed in areas prepared to receive fiU in layers not to exceed 6 inches in
compacted thickness. Each layer shaU have a uniform moistore content in the range that wiU aUow the
compaction effort to be effidentiy appUed to achieve the specified degree of compaction. Each layer shaU be
uiuformly compacted to the specified minimum degree of compaction with equipment of adequate size to
economicaUy compact the layer. Compaction equipment should dther be spedficaUy designed for soil
compaction or of proven reUabiUty. The minimum degree of compaction to be achieved is specified in dther
the Special Provisions or the recommendations contained in the preliminary geotechnical investigation
report.
When the stmctoral fiU material includes rocks, no rocks wiU be aUowed to nest and aU voids must be
carefully fiUed 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 stmctural fills and in non-
stmctoral fills is discussed in the geotechnical report, when appUcable.
Field observation and compaction tests to estimate the degree of compaction of the fiU wiU be taken by the
Geotechnical Engineer or his representative. The location and frequency of the tests shaU be at the
Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than
die required degree of compaction, the layer shaU be reworked to the satisfaction of the Geotechrucal
Engineer and untU the desired relative compaction has been obtained.
CWE 2040602.1 June 29, 2004 Appendix B, B-4
Fill slopes shaU be compacted by means of sheepsfoot roUers or otiier suitable equipment Compaction by
sheepsfoot roUer shaU be at vertical intervals of not greater than four feet In addition, fiU slopes at a ratio of
two horizontal to one vertical or flatter, should be trackroUed. Steeper fiU slopes shaU be over-built and cut-
back to finish contours after die slope has been constmcted. Slope compaction operations shaU result in aU
fill material six or more inches inward from die finished face of the slope having a relative compaction of at
least 90 percent of maximum dry densitj' or die degree of compaction spedfied in die Special Provisions
section of this spedfication. The compaction operation on the slopes shaU be continued until the
Geotechnical Engineer is of the opinion that the slopes wiU be surficiaUy stable.
Density tests in the slopes wiU be made by die Geotechnical Engineer during constmction of the slopes to
determine if the required compaction is being achieved. Where faiUng tests occur or otiier field problems
arise, the Contractor wiU be notified that day of such conditions by written communication from the
Geotechnical Engineer or liis representative in the form of a daily fidd report
If the mediod of achieving the required slope compaction selected by die Contractor fails to produce the
necessary results, the Contractor shaU rework or rebuild such slopes untU die required degree of compaction
is obtained, at no cost to the Owner or Geotechnical Engineer.
CUT SLOPES
The Engineering Geologist shaU inspect cut slopes excavated in rock or Uthified formational material during
the grading operations at intervals determined at his discretion. If any conditions not anticipated in the
preUminary report such as perched water, seepage, lenticular or confined strata of a potentiaUy adverse
natore, unfavorably mcUned bedding, joints or fault planes are encountered during grading, these conditions
shaU be analped by die Engineering Geologist and Geotechnical Engineer to determine if mitigating
measures are necessary.
Unless otherwise spedfied in the geotechnical report, no cut slopes shaU be excavated higher or steeper than
that aUowed by the ordinances of the controUing governmental agency.
ENGINEERING OBSERVATION
Field observation by the Geotechnical Engineer or his representative shaU be made during the filUng and
compaction operations so that he can express his opinion regarding the conformance of the grading with
acceptable standards of practice. Ndther the presence of the Geotechnical Engineer or his representative or
I
CWE 2040602.1 June 29, 2004 Appendix B, B-5
the observation and testing shaU release the Grading Contractor from his duty to compact aU fiU material to
die spedfied degree of compaction.
SEASON LIMITS
Fill shaU not be placed during unfavorable weatiier conditions. When work is intermpted by heavy rain,
filUng operations shaU not be resumed until the proper moisture content and density of the fiU materials can
be achieved. Damaged site conditions resulting from weather or acts of God shaU be repaired before
acceptance of work.
RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS
RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natoral
ground, compacted fiU, and compacted backfUl shaU be at least 90 percent For street and parking lot
subgrade, the upper six inches should be compacted to at least 95 percent relative compaction.
EXPANSIVE SOILS: DetrimentaUy expansive sod is defined as dayey soil which has an expansion index of
50 or greater when tested in accordance with the Uniform BuUding Code Standard 29-2.
OVERSIZED MATERIAL: Oversized fiU material is generaUy defined herein as rocks or lumps of soU
over 6 inches in diameter. Oversized materials should not be placed in fiU unless recommendations of
placement of such material is provided by the Geotechnical Engineer. At least 40 percent of the fiU soils
shaU pass through a No. 4 U.S. Standard Sieve.
TRANSITION LOTS: Where transitions between cut and fdl occur within the proposed budding pad, die
cut portion should be undercut a minimum of one foot below the base of the proposed footings and
recompacted as stmctoral backfiU. In certain cases that would be addressed in the geotechnical report,
special footing reinforcement or a combination of special footing reinforcement and undercutting may be
required.