HomeMy WebLinkAboutCT 05-06; CASSIA PROFESSIONAL OFFICES; GEOTECHNICAL INVESTIGATION; 2004-12-16GEOTECHNICAL INVESTIGATION
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
PREPARED FOR
O'DAY CONSULTANTS
CARLSBAD, CALIFORNIA
RECEIVED
.lAM 0 3 2006
ENG\NEER\NG
DEPARtMENT
DECEMBER 16, 2004 cr OS·oc,
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GEOeON
INCORPORATED
Project No. 07431-22-01
December 16, 2004
O'Day Consultants
2710 Loker Avenue, Suite 100
Carlsbad, California 92008-6603
Attention:
Subject:
Gentlemen:
Mr. Pat O'Day
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
GEOTECHNICAL INVESTIGATION
GEOTECHNICAL CONSULTANTS
In accordance with your authorization of our proposal LG-04483 dated November 1, 2004, we are
submitting the results of our geotechnical investigation for the subject site. The accompanying report
presents the findings and conclusions from our study.
Based on the results of our study, it is our opinion that the subject site can be developed as proposed,
provided the recommendations of this report are followed.
If you have any questions regarding this investigation, or if we may be of further service, please
contact the undersigned at your convenience.
E CON INCORPORATED
Paul Dunster
RG 6761
PD:JJV:MSC:anh
(6) Addressee
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Michael S. ChaPtn r--....
CEG 1149
6960 Flanders Drive &J San Diego, California 92121-297 4 ~ Telephone (858) 558-6900 II Fax (858) 558-6159
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TABLE OF CONTENTS
1. PURPOSE AND SCOPE ................................................................................................................. 1
2. SITE AND PROJECT DESCRIPTION ........................................................................................... 1
3. SOIL AND GEOLOGIC CONDITIONS ......................................................................................... 2
3.1 Topsoil (unmapped) ............................................................................................................... 3
3.1 Santiago Formation (Ts) .......................................................................... ' .............................. 3
4. GROlJNDW ATER ........................................................................................................................... 3
5. GEOLOGIC HAZARDS .................................................................................................................. 3
5.1 Faulting and Seismicity ...................................... : ................................................................... 3
5.2 Liquefaction .................................. ~ ........................................................................................ 5
5.3 Geologic Structure ................................................................................................................. 5
6. CONCLUSIONS AND RECOMMENDATIONS ........................................................................... 6
6.1 General ................................................................................................................................... 6
6.2 Soil and Excavation Characteristics ....................................................................................... 6
6.3 Seismic Design Criteria ......................................................................................................... 7
6.4 Grading .................................................................................................................................. 7
6.5 Slopes ..................................................................................................................................... 8
6.6 Terrace Drains ...................................................................................................... ' .................. 9
6.7 Foundation Recommendations ............................................................................................. 10
6.8 Foundations -General ......................................................................................................... 11
6.9 Concrete Slabs-on-Grade ..................................................................................................... 12
6.10 Lateral Loads ........................................................................................................................ 12
6.11 Preliminary Pavement Recommendations ............................................................................ 13
6.12 Corrosion Potential .............................................................................................................. 14
6.13 Site Drainage and Moisture Protection ................................................................................ 14
6.14 Slope Maintenance ............................................................................................................. :.15
6.15 Foundation and Grading Plan Review ................................................................................. 15
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map
Figure 3, Geologic Cross Section A-A'
Figure 4, Wall/Column Footing Dimension Detail
FigureS, Slope Stability Analysis -Fill Slopes
Figure 6, Surficial Slope Stability Analysis -Fill Slopes
APPENDIX A
FIELD INVESTIGATION
Figures A-1-A-6, Logs of Trenches
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TABLE OF CONTENTS (Continued)
APPENDIXB
LABORATORY TESTING
Table B-1, Summary of Laboratory Direct Shear Test Results
Table B-II, Summary of Laboratory Expansion Index Test Results
TableB-ill, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content Tests Re~ults
Table B-IV, Summary of Laboratory Resistance Value Test Results
Table B-V, Summary of Laboratory Water-Soluble Sulfate Test Results
Table B-VI, Summary of Laboratory Potential of Hydrogen (pH) and Resistivity Test Results
APPENDIXC
RECOMMENDED GRADING SPECIFICATIONS
LIST OF REFERENCES
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GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This geotechnical investigation has been prepared for an approximately three-acre site consisting of
undeveloped land located at the northeast corner of EI Camino Real and Cassia Road in Carlsbad,
California, (see Vicinity Map, Figure No.1). The purpose of the investigation was to evaluate the
surface and subsurface soil conditions and general site geology, identify any geotechnical constraints
that may exist on the property and, based on the conditions encountered, provide recommendations
relative to the geotechnical engineering aspects of site development. Locations of proposed structures
and mapped geology are depicted on the Geologic Map (Figure 2).
The scope of our investigation included a site reconnaissance, review of aerial photogra!,hs, a field
investigation, laboratory testing, engineering analyses, and preparation of this report. The field
investigation was performed on November 24, 2004 and consisted of the excavation of 6 backhoe
trenches. The trenching was performed to examine soil and geologic units, to delineate geologic
contacts and features within areas of proposed development, and to collect samples. Logs of
exploratory trenches and other details of the field investigation are presented in Appendix A.
Laboratory tests were performed on selected soil samples obtained from the trenches to determine
pertinent physical properties for engineering analyses. A discussion pertaining to the laboratory
testing and test results is presented in Appendix B.
The base map used to depict exploratory trench locations and site soil and geologic conditions (see
Figure 2, Geologic Map) is a topographic map depicting the approximate configuration of the
property, existing topography, and proposed improvements.
The conclusions and recommendations presented herein are based on analysis of the data obtained
from the exploratory trenches, laboratory tests, and our experience with similar soil and geologic
conditions.
2. SITE AND PROJECT DESCRIPTION
The site is a triangular-shaped parcel encompassing approximately 3 acres of undeveloped land
located to the east of EI Camino Real and north of the proposed extension of Cassia Road in
Carlsbad, California (see Vicinity Map, Figure 1). The northern approximately two-thirds of the site
is not currently proposed for development except for a proposed fill slope to accommodate a road
widening, and our investigation did not extend into this area. This area is currently designated as
Preserved Open Space.
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Topographically, the site is characterized by a north-south trending gully and an east-west trending
gully in the northern, Preserved Open Space portion of the site with elevations varying from a high of
approximately 315 feet Mean Sea Level (MSL) on the south side to a low of approximately 265 feet
MSL in the gullies. The 1.06-acre area that is proposed for development is located immediately north
of Cassia Road and south of the Preserved Open Space in the southernmost portion of the site. This
portion of the site is relatively flat with elevations varying from a high of approximately 322 feet
Mean Sea Level (MSL) along the southern boundary to a low of approximately 313 feet MSL.
Dense vegetation covers the majority of the site. There is some evidence of transitory occupation of
the site, consisting of old bedding, cardboard habitations, food waste, and other debris. Existing man-
made improvements consist of unpaved access roads along the east and south sides of the property. A
gas transmission line is present immediately east of the site.
Our review of the site plan indicates that the proposed site development will consist of the
construction of two 4,OOO-square-foot office buildings, driveways, at-grade parking lots, fill slopes,
concrete flatwork, underground utilities, the extension of Cassia Street onto the south side of the
property and the widening of EI Camino Real along the western side of the property. We expect that
the structures will be supported on shallow foundations with slab-on-grade floors.
In general, proposed grading will consist of cuts and fills of less than approximately 10 feet to
achieve the pad's grade and the construction of cut and fill slopes having maximum heights of less
than 10 feet at inclinations of 2: 1 (horizontal: vertical). A proposed 40-foot-high, 2: 1 slope is
indicated on Figure 2, within the Preserved Open Space to accommodate widening of EI Camino
Real. This area was not included in our field investigation due to access limitations. It appears that
the importation of fill soil will be necessary to grade the site as proposed.
The above locations and descriptions are based on a site reconnaissance and review of the referenced
topographic map. If development plans differ significantly from those described herein, Geocon
Incorporated should be contacted for review and possible revision to this report.
3. SOIL AND GEOLOGIC CONDITIONS
Soil and geologic conditions at the site were identified by review of published geologic literature for
the general area, observations of the exploratory excavations, and our experience with adjacent
properties. Topsoil and the Tertiary-age Santiago Formation comprise the units encountered at the
site. A geologic cross section is presented in Figure 3. Both are discussed below.
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3.1 Topsoil (unmapped)
Topsoil was encountered in all six trenches excavated at the site. These deposits appear to be between
1Y2 and 4 feet thick, and are composed of soft to firm clay, sandy clay and silt, as well as loose silty
sand. The topsoil is unsuitable in its present condition to support additional fill or structural
improvements and will require removal and recompaction.
3.1 Santiago Formation (Ts)
Soils encountered within this formation are predominantly massive, dense to very dense, moist silty
sand. In some sections, cobbles up to 8 inches in diameter were observed. The Santiago Formation
may also contain localized areas of highly cemented concretionary beds, although these were not
encountered during the cun'ent investigation. Previous experience indicates that such concretionary
beds can be difficult to excavate and may result in the production of oversize materials that will
require special handling and fill placement techniques. The Santiago Formation is adequate in its
present condition for support of structures and structural fills.
4. GROUNDWATER
Groundwater was not encountered during our field investigation to a maximum depth of 5 feet below
the existing ground surface and no seeps or springs were observed at the surface. Groundwater is not
anticipated to adversely impact the development of the property. However, it is not uncommon for
groundwater or seepage conditions to develop where none previously existed. Proper surface
drainage of irrigation and precipitation will be critical to future performance of the project.
5. GEOLOGIC HAZARDS
5.1 Faulting and SeismiCity
Based on our reconnaissance, evidence obtained in the exploratory excavations, and a review of
geologic maps, reports and aerial photos, the site is not located on any known "active" fault trace as
defined by the California Geological Survey (CGS).
The Rose Canyon Fault Zone, located approximately 6.2 miles west of the site, is the closest known
active fault. The CGS considers a fault seismically active when evidence suggests seismic activity
within roughly the last 11,000 years. The CGS has included portions of the Rose Canyon Fault within
an Alquist-Priolo Earthquake Fault Zone. Based upon a review of available geologic data and
published reports, the site is not located within a State of California Alquist-Priolo Earthquake Fault
Zone.
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Earthquakes that might occur on the Rose Canyon Fault or other faults within the southern California
and northern Baja California area are potential generators of significant ground motion at the site. In
order to determine the distance of known active faults to the site the computer program EQFAULT,
(Blake, 2000), was utilized. Principal references used within EQFAULT in selecting faults to be
included are Jennings (1975), Anderson (1984), and Wesnousky (1986). In addition to fault location,
EQF A ULT was used to estimate ground accelerations at the site for the maximum anticipated seismic
event.
Sixteen known active faults were identified within a search radius of 62 miles (100 kilometers) from
the site. The distance of the faults from the site, along with estimated maximum earthquake
magnitude and estimated peak site accelerations are presented in Table 5.1. The peak site acceleration
is based on attenuation relationships of Sadigh (1997) for rock sites. The results of the deterministic
analyses indicate that the Rose Canyon Fault is the dominant source of potential ground motion at the
site. Earthquakes having a maximum earthquake magnitude of 7.2 are considered to be representative
of the potential for seismic ground shaking at the site (from this fault). The "maximum magnitude
earthquake" is defined as the maximum earthquake that seems possible of occurring under the
presently known tectonic framework (California Division of Mines and Geology Notes, Number 43).
The estimated maximum earthquake ground acceleration from the Rose Canyon Fault is
approximately 0.40 g.
TABLE 5.1
MAXIMUM EARTHQUAKE MAGNITUDE AND PEAK SITE ACCELERATIONS*
Approximate Estimated Maximum Estimated :peak Site Fault Name Distance From Site
(miles) Earthquake Magnitude Accelerations (g)
Rose Canyon Fault Zone 6.2 7.2 0.40
Newport-Inglewood (offshore) 10 7.1 0.29
Coronado Bank 22 7.6 0.17 -
Elsinore-Julian 24 7.1 0.11
Elsinore-Temecula 24 6.8 0.09
Elsinore-Glen Ivy 37 6.8 0.05
San Joaquin Hills 40 6.6 0.04
Earthquake Valley 40 6.5 0.03
Palos Verdes 40 7.3 0.06
San J acinto-Anza 46 7.2 0.05
San Jacinto-San Jacinto Valley 48 6.9 0.04
San Jacinto-Coyote Creek 50 6.6 0.03
Newport-Inglewood (L.A. Basin) 51 7.1 0.04-
Chino-Central Ave. (Elsinore) 52 6.7 0,03
Elsinore-Coyote Mountain 54 6.8 0.03
Whittier 55 6.8 0.03
*From EQFAULT Computer Program (Blake 2000).
Project No. 07431-22-01 -4 -December 16, 2004
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While listing of peak accelerations is useful for comparison of potential effects of fault activity in a
region, other considerations are important in seismic design, including the frequency and duration of
motion and the soil conditions underlying the site. We recommend seismic design of the structures be
performed in accordance with California Building Code guidelines or other applicable guidelines.
The site could be subjected to moderate to severe ground shaking in the event of a major earthquake
on any of the faults referenced above or other faults in the Southern California, Northern Baja region.
With respect to seismic shaking, the site is considered comparable to the surrounding developed ~rea.
5.2 Liquefaction
Liquefaction is a phenomenon in which loose saturated and relatively cohesionless soil deposits
located beneath the groundwater table lose strength during strong ground motions. Primary factors
controlling liquefaction include intensity and duration of ground accelerations, characteristics of the
subsurface soil, in situ stress conditions and depth to groundwater. As groundwater was not
encountered and any loose soils will be removed during grading operations, the potential for
liquefaction occurring at the site is considered to be low.
5.3 Geologic Structure
The Santiago Formation encountered during the subsurface investigation was generally massive. A
review of Geologic Maps of the Northwestern Part of San Diego County, California, Tan and
Kennedy (1996), also indicates the bedding attitudes of the Santiago Formation, in the general
vicinity of the subject property, are generally flat.
Faults were not encountered during the subsurface investigation. None have been mapped on the site
by others according to the geologic literature that was reviewed.
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6. CONCLUSIONS AND RECOMMENDATIONS
6.1 General
6.1.1 No soil or geologic conditions were encountered at the site that, in the opinion of Geocon
Incorporated, would preclude the development of the property as planned provided the
recommendations of this report are followed.
6.1.2 The topsoil is considered unsuitable for the support offill, improvements, and/or structural
loading in its present condition and will require removal and compaction as described
herein.
6.1.3. Cuts less than approximately 10 feet are planned for a small portion of the site. Although
most of the sedimentary rock is excavatable with a backhoe, concretions, cemented zones
and very dense/very hard beds may be.encountered that will require a much greater effort
to excavate. Excavations within such zones can produce oversize materials that will require
special handling and placement in fill areas.
6.1.4 The proposed buildings will likely be founded on compacted fill excavated from the
Santiago Formation or imported and can be supported on a conventional, shallow
foundation system with a slab-on-grade floor system.
6.2 Soil and Excavation Characteristics
6.2.1 The on-site soil ranges from "very low" to "medium" expansion potential (Expansion
Index [EI] less than 90). Recommendations presented herein assume that the area to be . .
used for structures will be graded such that soils with an EI of 50 or less will be presentJo a
minimum depth of 4 feet below fmish grade. If soils with an EI greater than 50 are exposed
within this zone then modifications to the foundation recommendations of this report may
be necessary.
6.2.2 The topsoil can be excavated with light to moderate effort with conventional heavy duty
grading equipment. The Santiago Formation can likely be excavated with heavy effort.
Concretions and very dense beds may be encountered within the formation that require
much greater effort, and/or rock breaking. Any oversize materials generated may require
additional equipment to move them or reduce them to a manageable size.
Project No. 07431-22-01 -6-December 16, 2004
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6.3
6.3.1
6.4
6.4.1
6.4.2
6.4.3
Seismic Design Criteria
The site is located within Seismic Zone 4 according to the California Building Code
(CBC). Compacted fill or sedimentary rock will underlie the buildings. If the 2000 CBC is
utilized, Table 6.3 summarizes site design criteria. The values listed in the table are for
both Type B and Type A faults. The Rose Canyon Fault is located approximately 6.2 miles
west of the site.
TABLE 6.3
SEISMIC DESIGN PARAMETERS
Parameter Value CBC Refer.ence
Seismic Zone Factor 0.40 Table 16-1
Soil Profile Type Sc Table 16-J
Seismic Coefficient, CA 0.40 Table 16-Q
Seismic Coefficient Cv 0.56 Table 16-R
Near Source Factor, NA 1.00 Table 16-S
Near Source Factor Nv 1.00 Table 16T
Seismic Source B Table 16-U
Grading
All grading should be performed in accordance with the Recommended Grading
Specifications in Appendix C. Where the recommendations of this section conflict with
those of Appendix C, the recommendations of this section take precedence. All earthwork
should be observed and all fills tested for proper compaction by Geocon Incorporated.
Prior to commencing grading, a preconstruction conference should be held at the site with
the owner or developer, grading contractor, civil engineer and geotechnical engineer in
attendance. Special soil handling requirements can be discussed at that time.
Site preparation should begin with the removal of all deleterious material and vegetation.
The depth of removal should be such that the material exposed in cut areas and soil to be
used as fill are relatively free of organic matter. Material generated during stripping and/or
site demolition should be exported from the site.
6.4.4 All topsoil should be removed to expose competent formational soil. Removals should
extend for a distance of 5 feet beyond the proposed building footprints and a distance of
2 feet outside of proposed paved areas. Although not encountered, it is likely that
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6.4.5
6.4.6
6.4.7
6.4.8
6.4.9
6.5
6.5.1
potentially compressible alluvium exists below the proposed 40-foot ± fill slope along
EI Camino Real. This material, if present, should be removed to expose formational soil
prior to placing fill soil. Keying and benching as outlined in the grading specifications
(Appendix C) should be pelformed for all fill slopes.
After unsuitable materials have been removed as described above, the site should be
brought to final sub grade elevations with structural fill compacted in layers. Layers of fill
should be no thicker than will allow for adequate bonding and compaction. All fill should
be compacted to at least 90 percent of laboratory maximum dry density as determined by
ASTM Test Procedure D 1557-02 at or above optimum moisture content. Fill areas with
test results indicating soil moisture contents less than that specified, will require additional
moisture conditioning prior to placing additional fill.
Cut-fill transitions could occur across a building pad. Where a cut-fill transition occurs, the
building pad should be undercut 3 feet below final grade and replaced with properly
compacted fill. The undercut should extend 5 feet beyond perimeter footing lines.
Any oversize cemented chunks generated during excavations of cemented zones in the
formational materials should be broken down to less than 2 feet in diameter prior to
placement in compacted fill areas. These oversize materials can be placed in deeper fill
I areas. Oversize materials should be kept at least 10 feet below the finished pad grade or
deepest utility line, whichever is greater. Oversize materials should be placed in accordance
with the recommendations presented in the Recommended Grading Specifications in
Appendix C.
In general, soil imported to the site should be free of oversize material and should possess
an expansion index less than 50. If imported fill soil will be used to construct the fill siope
adjacent to the preserved open-space area, the soil should be tested for acceptable shear
strength parameters prior to delivery to the site.
The proposed building pad and parking lot area should be graded such that the soil within 4
feet of finish grade possesses an EI of less than 50. Where fill areas are less than 4 feet
thick, the existing ground should be undercut at least 4 feet below finish grade and replaced
with properly compacted "very low" to "low" expansive fill soil.
Slopes
Slope stability analyses for fill slopes were performed using average drained direct shear
strength test results from representative samples of the on site soils that were remolded to
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6.5.2
6.5.3
approximately 90 percent of maximum dry density at near optimum moisture content. The
results of the analyses indicate that the proposed 2: 1 (horizontal:vertical) fill slopes have a
calculated factor of safety of at least 1.5 against both deep seated and surficial instability.
The results of the analyses are shown on Figures 5 and 6. Proposed imported fill soil
should be tested for acceptable shear strength parameters prior to delivery to the site.
. .
The outer 15 feet of fill slopes, measured horizontally to the slope face, should be
composed of properly compacted granular soil fill to reduce the potential for surficial
sloughing.
All fIll slopes should be overbuilt at least 3 feet horizontally and cut back to the design
finish grade. As an alternative, fill slopes may be compacted by back-rolling at vertical
intervals not to exceed 4 feet a:n~ then track-walked with a Caterpillar D8 tractor, or
equivalent, upon completion such that the fill soils are uniformly compacted to at least 90
percent relative compaction to the face of the finished slope.
6.5.4 Cut slopes in the Santiago Formation should be stable at a gradient of 2: 1 provided the face
of the slopes are free of adversely oriented joints or fractures.
6.5.5 We recommend that all cut slopes be observed during grading by an engineering geologist
to check that the soil and geologic conditions do not differ significantly from those
anticipated and to observe whether adverse bedding, fractures or joints exist.
6.5.6 Drainage devices should be provided to prevent the discharge of water over the tops of all
slopes.
6.5.7 Temporary slopes should conform to current CAL OSHA requ~ements. Slopes excavated
in compacted fill and formational soils should be no steeper than 1:1 and %:1, respectively,
up to a maximum height of 20 feet. Temporary slopes greater than 20 feet in height should
be evaluated by Geocon during construction. The contractor is responsible for providing a
safe working environment adjacent to temporary excavations and should have a COmpetent
person (OSHA) on site to take appropriate measures where required.
6.5.8 All slopes should be planted, drained and properly maintained to reduce erosion.
6.6 Terrace Drains
6.6.1 The use of terrace drains on fill slopes is not considered necessary to. maintain gross
stability of the slopes. Based on past experience with similar projects, properly constructed
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6.6.3
6.6.4
and maintained terrace drains may reduce slope erosion, particularly on fill slopes.
However, improperly-maintained terrace drains can result in significant erosion and
potential slope distress. Terrace drains that are allowed to fill with debris may concentrate
surface runoff down the slope face thereby resulting in deep gullies. ;£:f terrace drains are
planned they should be properly designed and maintained.
All terrace drains should direct the flow of water into storm drains or other suitable
drainage facilities.
All terrace drains should be sized to accommodate the maximum flow of water anticipated
from the drainage area above, under the design precipitation event.
Where used, it is recommended that terrace drains be constructed at a drainage gradient of
at least 5 percent. In addition, a maintenance program should be devised and followed,
which clearly designates the persons or agencies responsible for maintaining terrace drains
within specific areas.
6.7 Foundation Recommendations
6.7.1 If all existing topsoil is removed and recompacted and undercuts are perfor:rned as
described previously a conventional shallow foundation system is considered suitable for
support of planned structural loads. The foundation recommendations that follow are based
upon "low" expansive (Expansion Index less than 50) soil within approximately 4 feet of
finish subgrade elevations. If more expansive soil is encountered within 4 feet of finish
grade elevation, modification to the foundation recommendations may be necessary.
6.7.2 Conventional continuous footings should be at least 12 inches wide and found~d a
minimum of 18 inches below lowest adjacent pad grade. Isolated spread footings should be
a minimum of 2 feet square and founded at least 18 inches below lowest adjacent pad
grade. Foundations so proportioned may be designed for an allowable soil bearing pressure
of 3,000 pounds per square foot (psf) for foundations bearing on properly compacted fill or
formational soils.
6.7.3 Continuous footings should be reinforced with two No.4 steel reinforcing bars, one placed
near the top of the footing and one near the bottom. The project structural engineer should
design reinforcement for spread footings.
6.7.4 The recommended allowable soil bearing pressures may be increased by 300 psf and
500 psf for each additional foot of foundation width and depth, respectively, up to a
maximum allowable soil bearing pressure of 5,000 psf.
Project No. 07431-22-01 -10-December 16, 2004
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6.7.5
6.7.6
6.7.7
The above recommended soil bearing pressures are for dead plus live loads only. The
allowable pressures may be increased by up to one-third when considering transient loads
such as those due to wind or seismic forces.
Static settlement due to foundation loads is estimated to be approximately Yz inch.
The above foundation dimensions and minimum reinforcement recommendations are based
upon soil conditions only and are not intended to be used in lieu of thos'e required for
structural purposes. A typical footing dimension detail depicting lowest adjacent pad grade
is presented on Figure 4.
6.7.8 No special subgrade pre saturation is deemed necessary prior to placement of concrete.
However, the slab and foundation subgrade should be moistened as necessary to maintain a
moist condition as would be expected in any such concrete placement.
6.8 Foundations -General
6.8.1 Where buildings or other improvements are planned near the top of a slope, special
foundations and/or design considerations are recommended due to the tendency for lateral
soil movement to occur.
• Building footings that are planned near the top of a slope should be deepened such
that the bottom outside edge of the footing is at least 7 feet horizontally fJ;om the
face of the slope.
• Although other improvements that are relatively rigid or brittle, such as concrete
flatwork or masonry walls may experience some distress if located near the top of a
slope, it is generally not economical to mitigate this potential. It may be possible,
however, to incorporate design measures that would permit 'Some lateral soil
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
6.8.2 No special subgrade preparation is deemed necessary prior to placing concrete, however,
the exposed foundation and slab subgrade soils should be sprinkled, as necessary, to
maintain a moist soil condition as would be expected in any such concrete placement.
6.8.3 Foundation excavations should be observed by a representative of Geocon Incorporated
prior to the placement of reinforcing steel or concrete to verify that the exposed soil
conditions are consistent with those anticipated. If unanticipated soil conditions are
encountered, foundation modifications may be required.
Project No. 07431-22-01 -11 -December 16, 2004
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6.9
6.9.1
6.9.2
6.9.3
Concrete Siabs-on-Grade
Building (interior) concrete slabs-on-grade should be at least 5 inches thick and reinferced
with No.3 steel reinforcing bars placed 24 inches on center in both horizontal directiens
and positioned within the upper one-third of the slab. The concrete slabs should be
underlain by at least 4 inches of clean sand and, where moisture sensitive floor coverings
are planned, a visqueen moisture barrier placed at the midpoint of the sand cushion should
be provided.
All concrete slabs should be provided with adequate construction joints and/or expansion
joints to control shrinkage cracking. The spacing should be determined by the project
structural engineer based upon the intended slab usage, thickness, and reinforcement. The
structural engineer should take into consideration criteria of the American Concrete
Institute when establishing crack control spacing patterns.
Exterior slabs not subjected to vehicular traffic should be at least 4 inches thick and
reinforced with 6x6-W2.91W2.9 (6x6-6/6) welded wire mesh. The mesh should be placed
within the upper one-third of the slab. Proper mesh positioning is critical to future
performance of the slab. It has been our experience that the mesh must be physically pulled
up into the slab after concrete placement. The contractor should take extra measures to
provide proper mesh placement. Prior to construction of slabs, the subgrade should be
moisture conditioned to at least optimum moisture content and compacted to at least 90
percent relative compaction.
6.9.4 The recommendations of this report are intended to reduce the potential for cracIdng of
slabs due to slight differential movement of the subgrade soils. However, even with the
incorporation of the recommendations presented herein, foundations, stucco walls, . and
slabs-on-grade may exhibit some cracking due to soil movement and/or shrinkage. The
OCCUlTence of concrete shrinkage cracks is independent of' the supporting soil
characteristics. Their occurrence may be reduced and/or controlled by limiting the slump of
the concrete, proper concrete placement and curing, and by the placement of crack control
joints at periodic intervals, in particular, where re-entrant corners occur.
6.10
6.10.1
Lateral Loads
For resistance to lateral loads, an allowable passive earth pressure equivalent to a fluid
density of 300 pcf is recommended for footings or shear keys poured neat against properly
compacted granular fill soil or undisturbed natural soil. The allowable passive pressure
assumes a horizontal sUlface extending away from the base of the wall at least 5 feet or
three times the height of the surface generating the passive pressure, whichever is greater.
Project No. 07431-22-01 -12-December 16, 2004
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The upper 12 inches of material not protected by floor slabs or pavement should not be
included in the design for lateral resistance. An allowable friction coefficient of 0.4 may be
used for resistance to sliding between soil and concrete. This friction coefficient may be
combined with the allowable passive earth pressure when determining resistance to lateral
loads.
6.11 Preliminary Pavement Recommendations
6.11.1 The following recommendations are for preliminary purposes only and are provided for
private driveways and parking areas. The final pavement section design will depend upon
soil conditions exposed at sub grade elevation and the results of Resistance Value (R-Value)
tests of the subgrade soils. The following preliminary pavement section recommendations
are based on one R -Value test result and experience with similar soil conditions. Sections
are presented for flexible (asphalt concrete) pavement.
TABLE 6.11
PRELIMINARY FLEXIBLE PAVEMENT SECTION
Assumed Assumed Asphalt Class 2
Location Traffic R-Value Concrete Aggregate
Index (inches) Base (inches)
Parking stalls for automobiles and 4.5 <5 3.0 9.0 light-duty vehicles
Driveways for automobiles and light-5.5 <5 3.0 13.0 duty vehicles
Driveways for heavy trucks and buses 7.0 <5 4.0 16.5
6.11.2 Prior to constructing pavements the upper 12 inches of subgrade soil should be sca.rified,
moisture conditioned and compacted to a minimum of 95 percent relative compaction.
6.11.3 Class 2 base should conform to Section 26-1.-02A of the Standard Specifications for The
State of Califomia Department of Transportation (Caltrans) and should be compacted to a
minimum of 95 percent of the maximum dry density at near optimum moisture content.
The asphalt concrete should conform to Section 203-6 of the Standard Specifications for
Public Works Construction (Green Book).
6.11.4 Where trash bin enclosures are planned within asphalt paved areas, it is recommended that
the pavement sections consist of 7 inches of Portland cement conc~ete (minimum Modulus
of Rupture of 600 psi) reinforced with No.4 bars spaced at 18 inches in each horizontal
Project No. 07431-22-01 -13 -December 16, 2004
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direction. The concrete should extend into the roadway sufficiently so that the front wheels
of the trash truck are on the concrete when loading.
6.11.5 The performance of asphalt concrete pavements and concrete pavements is highly
dependent upon providing positive surface drainage away from the edge of the pavement.
Ponding of water on or adjacent to the pavement wi111ikely result in pavement distress and
sub grade failure. If planter islands are proposed, the perimeter curb should extend at least
6 inches below the subgrade elevation of the adjacent pavement. In addition, the surface
drainage within the planter should be such that ponding will not occur.
6.12
6.12.1
Corrosion Potential
Potential of Hydrogen (pH) and resistivity tests were performed on a sample selected at
random to generally evaluate the corrosion potential to subsurface structures. The tests
were performed in accordance with California Test Method No. 643 and indicate that a
high potential for corrosion of buried metals exists on site. The results are presented in
Appendix B and should be considered for design of underground structures.
6.12.2 Laboratory tests were performed on a sample of the site materials to determine the
percentage of water-soluble sulfate content. Results from the laboratory water-soluble
sulfate test are presented in Appendix B and indicate that the on-site materials possess
"negligible" sulfate exposure to concrete structures as defined by UBC Table 19-A-4.
6.12.3
6.13
6.13.1
Geocon Incorporated does not practice in the field of corrosion engineering. If corrosion
sensitive improvements are planned, it is recommended that further evaluations by a
corrosion engineer be performed to incorporate the necessary precautions to avoid
premature corrosion of buried metal pipes and concrete structures in direct contact -with
the soils.
Site Drainage and Moisture Protection
Adequate drainage is critical to reduce the potential for differential soil movement, erosion,
and subsurface seepage. Under no circumstances should water be allowed to pond adjacent
to footings. The site should be graded and maintained such that surface drainage is directed
away from structures and the top of slopes into swales or other controlled drainage devices.
Roof and pavement drainage should be directed into conduits that carry runoff away from
the proposed improvements.
Project No. 07431-22-01 -14-December 16, 2004
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6.13.2 Landscaping planters adjacent to paved areas are not recommended due to the potential for
surface or irrigation water to infiltrate the pavement's subgrade and base course. We
recommend that subdrains to collect excess ilTigation water and transmit it to drainage
structures, or impervious above-grade planter boxes be used. In addition, where
landscaping is planned adjacent to the pavement, we recommended construction of a cutoff
wall along the edge of the pavement that extends at least six inches below the bottom of the
base material.
6.14
6.14.1
6.15
6.15.1
Slope Maintenance,
Slopes that are steeper than 3: 1 (horizontal:vertical) may, under conditions that are difficult
to prevent and predict, be susceptible to near surface (surficial) slope instability. The
instability is typically limited to the outer three feet of the slope and usually does not
directly impact the improvements on the pad areas above or below the slope. The
occurrence of surficial instability is more prevalent on fill slopes and is generally preceded
by a period of heavy rainfall, excessive irrigation, or the migration of subsurface seepage.
The disturbance and/or loosening of the surficial soils, as might result from root growth,
soil expansion, or excavation for irrigation lines and slope planting, mllY also be a
significant contributing,factor to surficial instability. It is, therefore, recommended that, to
the maximum extent practical: (a) disturbedlloosened surficial soils be either removed or
properly recompacted, (b) irrigation systems be periodically inspected and maintained to
eliminate leaks and excessive irrigation, and (c) surface drains on and adjacent to slopes be
periodically maintained to preclude ponding or erosion. Although the incorporation of the
above recommendations should reduce the potential for surficial slope instability, it will
not eliminate the possibility, and, therefore, it may be necessary to rebuild or repair a
portion of the project's slopes in the future.
Foundation and Grading Plan Review
Geocon Incorporated should review the grading plans and foundation plans for the project
prior to final design submittal to determine if additional analysis and/or recommendations
are required.
Project No. 07431-22-01 -15 -December 16, 2004
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LIMITATIONS AND UNIFORMITY OF CONDITIONS
The recommendations of this report pertain only to the site investigated and are based upoli
the assumption that the soil conditions do not deviate from those disclosed in the
investigation. If any variations or undesirable conditions are encountered during construction,
or if the proposed construction will differ from that anticipated herein, Geocon Incorporated
should be notified so that supplemental recommendations can be given. The evaluation or
identification of the potential presence of hazardous or corrosive materials was not part of the
scope of services provided by Geocon Incorporated.
This report is issued with the understanding that it is the responsibility of the owner, or of his
representative, to ensure that the information and recommendations contained herein are
brought to the attention of the architect and engineer for the project and incorporated into the
plans, and the necessary steps are taken to see that the contractor and subcontractors carry out
such recommendations in the field.
The findings of this report are valid as of the present date. However, changes in the
conditions of a property can occur with the passage of time, whether they be due to natural
processes or the works of man on this or adjacent properties. In addition, changes in
applicable or appropriate standards may occur, whether they result from legislation or the
broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly
or partially by changes outside our control. Therefore, this report is subject to review and
should not be relied upon after a period of three years.
Project No. 07431-22-01 December 16, 2004
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SOURCE: 2004 THOMAS BROTHERS MAP
SAN DIEGO COUNTY, CALIFORNIA
REPRODUCED WITH PERMISSION GRANTED BY THOMAS BORTHERS MAPS,
THIS MAP IS COPYRIGHT BY THOMAS BROS, MAPS. IT IS UNLAWFUL TO COPY
OR REPRODUCE ALL OR ANY PART THEREOF. WHETHER FOR PERSONAL USE OR
RESALE. WITHOUT PERMISSION.
GEDeON
INCORPORATED o
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121 -2974
PHONE 858 558-6900 -FAX 858 558-6159
PD/MM I I DSKlEOOOO
MiecelaffemplaleslPlalol IT empicrtetl/GeoteehlA Portrait
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NO SCALE
VICINITY MAP
CASSIA ROAD SITE
CARLSBAD I CALIFORNIA
DATE 12-16-2004/ PROJECT NO. 07431 -22 -01 I FIG. 1
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i---PROPOSED BUILDING-'
LOCATION· , _ J PROPOSE~
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---
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.......... _1-
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DISTANCE
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SCALE: 1"=40'
HORIZONTAL = VERTICAL
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-~ 1------. - -r ---,-'
240 280 320 360
GEOLOGIC CROSS SECTION A-A'
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
GEOeON
INCORPORATED o
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE· SAN DIEGO, CAUFORNIA 92121· 297 A
PHONE 858558·6900· FAX 858 558-6159
PROJECT NO. 07431 -22 -01
FIGURE 3
DATE 12-16-2004
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CONCRETE SLAB
PAD GRADE
COLUMN FOOTING
CONCRETE SLAB r n
NO SCALE
* .... SEE REPORT FOR FOUNDATION WITDH AND DEPTH RECOMMENDATION
WALL / COLUMN FOOTING DIMENSION DETAIL
GEDeON o INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 -FAX 858 558-6159
PD/MM I I DSKlEOOOO
COlFOOT2DWG/IIM
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
DATE 12-16-2004 I PROJECT NO. 07431-22-01 I FIG.4
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ASSUMED CONDITIONS:
SLOPE HEIGHT H = 40 feet
SLOPE INCLINATION 2.0: 1.0 (Horizontal: Vertical)
TOTAL UNIT WEIGHT OF SOIL Yt = 130 pounds per cubic foot
ANGLE OF INTERNAL FRICTION <I> = 30 degrees
APPARENT COHESION C = 300 pounds per square foot
NO SEEPAGE FORCES
ANALYSIS:
AC$ = yHtan¢ EQUATION (3-3), REFERENCE 1
C
FS NcfC = --EQUATION (3-2), REFERENCE 1
yH
AC$ = 10.0 CALCULATED USING EQ. (3-3)
Nef = 34 DETERMINED USING FIGURE 10, REFERENCE 2
FS = 1.9 FACTOR OF SAFETY CALCULATED USING EQ. (3-2)
REFERENCES:
1 ...... Janbu, N., Stability Analysis of Slopes with Dimensionless Parameters, Harvard Soil Mechanics
Series No. 46,1954
2 ...... Janbu, N., Discussion of J.M. Bell Dimensionless Parameters for Homogeneous Earth Sipes,
Journal of Soil Mechanicx and Foundation Design, No. SM6, November 1967
GEOCON
INCORPORATED o
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 -FAX 858 558-6159
KC/KC I I
SLOPE STABILITY ANALYSIS -FILL SLOPES
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
DATE I PROJECT NO. 07431-22-01 IFIG.5
ASSUMED CONDITIONS:
ANALYSIS:
REFERENCES:
SLOPE HEIGHT H = Infillte
SLOPE INCLINATION 2.0 : 1.0 (Horizontal: Vertical)
SLOPE ANGLE = 26.6 0
DEPTH OF SATURATION Z = 3 feet
UNIT WEIGHT OF WATER Yw 62.4 pounds per cubic foot
TOTAL UNIT WEIGHT OF SOIL Yt = 130 pounds per cubic foot
ANGLE OF INTERNAL FRICTION ~ = 30 degrees
APPARENT COHESION C = 300 pounds per square foot
SLOPE SATURATED TO VERTICAL DEPTH Z BELOW SLOPE FACE.
SEEPAGE FORCES PARALLEL TO SLOPE FACE.
FS = C +(YI -yJZ ·cos2 i ·tan¢ =
YI . Z . sin i . cos i
5.2
1 ...... HaefeJi, R. The Stability of Slopes Acted Upon by Parallel Seepage, Proc. Second International
Conference, SMFE, Rotterdam, 1948, 1, 57-62.
2 ...... Skempton, A. W., and F. A. Delory, Stability of Natural Slopes in London Clay, Proc. Fourth
Intemational Conference, SMFE, London, 1957,2,378-81.
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 -FAX 858 558-6159
KC/KC I I
SURFICIAL SLOPE STABILITY -FILL SLOPES
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
DATE J PROJECT NO. 07431-.z~-01 IFIG.6
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APPENDIX A
FIELD INVESTIGATION
The field exploration was performed on November 24 2004, and consisted of excavation of 6
backhoe trenches at the approximate locations shown on Figure 2. The trenches were excavated to
depths of between 3 and 5 feet below the existing ground surface using a John Deere 450 Backhoe.
Bulk and chunk samples were collected from selected depths in the trench.es.
The soil conditions encountered in the trenches were visually examined, classified, and logged in
general conformance with the American Society for Testing and Materials (ASTM) Practice for
Description and Identification of Soils (Visual -Manual Procedure D 2488-00). The logs of the
exploratory trenches are presented on Figures A-I through A-6. The logs depict the various soil types
encountered and indicate the depths at which samples were obtained.
Project No. 07431-22-01 December 16, 2004
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PROJECT NO. 07431-22-01
>-
DEPTH (!)
9 IN SAMPLE
0 NO. FEET :r: I-:::i
~ 0 TI-I ~ -Tl-2 .J:
Tl-3 p . -
~ 2 -_ . tJ .
Tl-4 -0--. '-~
'0
~
0:: w I-~ SOIL
Cl CLASS Z ::> (USCS)
0 0:: (!)
CL
Sw
TRENCH T 1 Zw.-. ~ w~ QUt w-:-o::~ ~z_ ::>1-~(/) zu.. ~q I-Z
ELEV. (MSL.) 317' DATE COMPLETED 11·24-~OO4 ti:i!!2~ (/)lLI -I-'0.. Oz Z(/)...J >-~ WW[lJ 0:: ::2EO
EQUIPMENT JD 4S0-C 0..0::~ Cl U
MATERIAL DESCRIPTION
TOPSOIL
Soft, wet, red-brown, Sandy CLAY
-100.0 20.7
SANTIAGO FORMATION
Very dense, moist, yellow, fine to coarse SAND with Cobbles up to 8" r-
diameter 118.l 5.5
TRENCH TERMlNATED AT 3 FEET
.
07431-22-01.GPJ Figure A-1,
I Log of Trench T 1, Page 1 of 1
\ ~----------------------------------~ l
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SAMPLE SYMBOLS o ... SAMPLING UNSUCCESSFUL
~ ,._ DISTURBED OR BAG SAMPLE
(] ... STANDARD PENETRATION TEST
iiJ ,.. CHUNK SAMPLE
•... DRIVE SAMPLE (UNDISTURBED)
.t: .,. WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED_ IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES,
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PROJECT NO. 07431-22-01
>-
DEPTH C)
0
IN SAMPLE ...J 0 NO. J: FEET !::: ...J
,... 0 ~ T2-1 ~ ,. 2 -
c--~
-4 -~
T2-2 :·1··l l ri. 'f
Figure A-2,
~ w ~ SOIL ~ CLASS Z :::> (USCS)
0 ~ (9
CL
SM
TRENCH T 2 zw~· ~ ~ Q()~ w~
I-Zu... rJ)--:-~~
~~(i'j zu... :::>~
~q I-Z
ELEV. (MSL.) 316%' DATE COMPLETED 11-24-2004 tu!!2~ rJ)UJ >-e:. -~ zC/)...J Oz
wUJ[!J ~ :2:0
EQUIPMENT a..~~ 0 () JD 450-C
MATERIAL DESCRIPTION -
TOPSOIL
Soft, saturated, brown, Sandy CLAY
~ 9S.1 2S.9
-Becomes wet at 1 Y:z' -
-
SANTIAGO FORMATION 10S.7 16.4
Very dense, moist, yellow-tan, Silty, fme to coarse SAND
TRENCH TERMINATED AT S FEET
-
07431-22-01.GPJ
I Log of Trench T 2, Page 1 of 1
t ~----------------------~ o ... SAMPLING UNSUCCESSFUL IJ ... STANDARD PENETRATION TEST •... DRIVE SAMPLE (UNDISTURBED) SAMPLE SYMBOLS I ~ DISTURBED OR BAG SAMPLE IiiiJ ... CHUNK SAMPLE .y. ... WATER TABLE OR SEEP.o;GE
I NOTE: THE LOG OF SUBSURFACE CONDITI~~S SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
II
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PROJECT NO. 07431-22-01
0:: W >-~ DEPTH (!) 0 s: IN SAMPLE -I 0 0
FEET NO. J: Z
!:: ;:)
0 -I 0:: (!)
I-0 :1· Il T3-2
"1'.·!·1 T3-1
i--~ c-
-2 -:·I··ll
T3-3 "1'.·!·1
-.'/ .!:.!.
. f j .j
:
I
:
Figure A-3,
SOIL
' CLASS
(USCS)
SM
CL
SM
TRENCH T 3 zw ...... ~ w~ OUt 'i= Z c;;-=-o::~
~i=5Ci3 Zu.. ;:)r-
~c..:! J-Z
ELEV. (MSL.) 321' DATE COMPLETED 11.24·2004 I:i:i~~ Cf.JW
>-e:,. 5~ ZCf.J-I UJWIlJ 0:: :2:0
EQUIPMENT a.0::~ 0 () JD 450·C
MATERIAL DESCRIPTION
TOPSOIL 110.5 13.0
Loose, saturated, brown, Silty, fme to medium SAND
------------------------------------1-------Firm, wet, brown, Sandy CLAY
SANTIAGO FORMATION
Very dense, moist, yellow-tan, Silty, fine to medium SAND 112.7 12.6
c-
TRENCH TERMINATED AT 3Y2 FEET
-
07431-22-01.G'pJ
I log of Trench T 3, Page 1 of 1
I ~----------------------------~~ I
il
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SAMPLE SYMBOLS o ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
IJ ... STANDARD PENETRATION TEST
iJ ... CHUNK SAMPLE
.... DRIVE SAMPLE (UNDISTURBED)
,!: ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
,
II PROJECT NO. 07431-22-01
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IN
FEET
I-0
r-
2
I-
I-4
~ >-LLJ I-C!l ~ 0 SAMPLE ...J 0 Cl NO, r Z I-;:,
::J ~ C!l
..
-
..
-T4-1
~ -
-
T4-2 :'1. 'I-l -J.j. 'f T4-3
TRENCH T 4 ZUJ~ ~ w~ QUt
SOIL 00"'":" a::~ f-Z .... ;:,1-~~CI) ZLL ~q I-Z CLASS ELEV. (MSL.) 321' DATE COMPLETED 11·24·2004 f-005: Cl)UJ W-O >-e:--l-(USCS) ZOO...J Oz
W UJm ~ :20
EQUIPMENT JD 450·C a.C::~ Cl ()
MATERIAL DESCRIPTION
TOPSOIL
Soft, wet, brown, Sandy SILT
'-ML
I-109.9 10.3 ---------------------------------r--"","-t-------Finn, moist, brown, CLAY
CL I-
SANTIAGO FORMATION
SM Very dense, moist, yellow-tan, Silty, fme to coarse SAND -
TRENCH TERMINATED AT 4\1, FEET
.
1 Figure A-4, 07431-22-01,GPJ I Log of Trench T 4, Page 1 of 1
1 SAMPLE SYMBOLS 0 .. , SAMPLING UNSUCCESSFUL IJ ... STANDARD PENETRATION TEST .... DRIVE SAMPLE (UNDISTURBED)
I ~ .. , DISTURBED OR BAG SAMPLE ~ ... CHUNK SAMPLE Y ... WATER TABLE OR SEEPAGE
l NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED, IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES,
:1 i
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jl PROJECT NO. 07431-22-01
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DEPTH (!) SOIL iZz 00--:-0:: ......
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IN SAMPLE ...J Il~ CLASS ~q I-Z 0 ELEV. (MSL.) 319' DATE COMPLETED 11-24-2004 tuCl)$ Cl)W
FEET NO. :c -0 >-e:. -l-
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EQUIPMENT JD 450-C Cl U
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I MATERIAL DESCRIPTION
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TS-2 CL Soft, wet, brown, Sandy CLAY 98.9 22.3
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:-1·'·'1 SANTIAGO FORMATION -2 -l,'f Very dense, moist, yellow-brown, Silty, fine to coarse SAND i-
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TRENCH TERMINATED AT 5 FEET
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1 . t FIgure A-5, 07431-22-01.GPJ
I, log of Trench T 5, Page 1 of 1
I SAMPLE SYMBOLS 0 ... SAMPLING UNSUCCESSFUL (] ... STANDARD PENETRATION TEST .... DRIVE SAMPLE (UNDISTURBED)
\ ~ ... DISTURBED OR BAG SAMPLE IiiJ ... CHUNK SAMPLE Y ... WATER TABLE OR SEEPAGE
,I NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION ANDATT:E DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
II PROJECT NO. 07431-22-01
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SOIL
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TRENCH T 6 zw~ ~ w~ QOr-: I-Zl:!:: 05-:--a::~ , . ~;::C/,) Zu. ::::lJ-
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ELEV. (MSL.) 313W DA TE COMPLETED 11-24-2004 1-(1)$ ~I:±! W-O >-lh Z(l)·...J Oz w LUC) a:: :?:o
EQUIPMENT J0450-C a..a::~ 0 0
MATERIAL DESCRIPTION
TOPSOIL
Finn, wet, reddish brown, Sandy CLAY 93.1 24.8 .,.
SANTIAGO FORMATION
Very dense, moist, yellow-tan, Silty SAND
I-113.9 14.9
TRENCH TERMINATED AT 5 FEET
.
I re A-6, 07431-22-01.GPJ
\ . Log of Trench T 6, Page 1 of 1
t. SAMPLE SYMBOLS o ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
[) ... STANDARD PENETRATION TEST
~ ... CHUNK SAMPLE
.... DRIVE SAMPLE (UNDISTURBED)
.!. ... WATER TABLE OR SEEPAGE
OTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
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APPENDIX B
lABORATORY TESTING
The results of laboratory testing performed as part of the geotechnical investigation performed for the
property are presented below. Laboratory tests were performed in accordance with generally accepted
test methods of the American Society for Testing and Materials (ASTM) or other suggested
procedures. Disturbed bulk samples remolded to selected densities and undisturbed samples were
subjected to drained direct shear testing. Expansion Index testing, R-Value testing, and testing to
determine compaction, pH, resistivity, and water-soluble sulfate content characteristics were
performed. Results of the tests are presented in tabular form. The in-place dry density and moisture
content of the samples tested are presented on the logs, Appendix A.
Sample
No.
T3-1*
T4-3
TABLE B-1
SUMMARY OF lABORATORY DIRECT SHEAR TEST ReSULTS
ASTM D 3080-03
Dry Density Moisture Content Unit Cohesion Angle of Shear
(pet) (%) (pst) , Resistance (degrees)
114.9 9.9 351 15
107.4 5.2 360 38
* Sample remolded to approximately 90 percent relative compaction at approximately optimum moisture content.
TABLE B-II
SUMMARY OF lABORATORY EXPANSION INDEX TEST RESULTS
ASTM D 4829-03
Sample Moisture Content Dry Density Expansion
No. Before Test (%) After Test (%) (pet) Index
Tl-l 11.3 20.0 106.0 22
Project No. 07431-22-01 -B-1 -December 16, 2004
TABLE B-III
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY
AND OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557-02
Sample Description Maximum Dry Optimum Moisture
No.
T3-1
Density (pet) Content (% dry wt.)
Silty, fine to medium SAND 128.5 9.2
TABLE B-IV
SUMMARY OF LABORATORY RESISTANCE VALUE TEST RESULTS
ASTM D 2844-01
Sample No. Description R-Value
T5-1 Brown, Sandy CLAY <5
TABLE B-V
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CTM NO. 417
Sample No. Water Soluble Sulfate (%)
T1-1 0.027
TABLE B-VI
SUMMARY OF LABORATORY POTENTIAL OF
HYDROGEN (pH) AND RESISTIVITY TEST RESULTS
(CALIFORNIA TEST NO. 643)
Sample No. pH Resistivity (ohm centimeters)
T1-1 4.2 3,583
Project No. 07431-22-01 -B-2-December 16, 2004
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APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
FOR
CASSIA ROAD SITE
CARLSBAD, CALIFORNIA
PROJECT NO. 07431-22-01
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1.1.
1.2.
1.3.
2.1.
2.2.
2.3.
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
These Recommended Grading Specifications shall be used in conjunction with the
Geotechnical Report for the project prepared by Geocon Incorporated. The
recommendations contained in the text of the Geotechnical Report are a part of the
earthwork and grading specifications and shall supersede the provisions contained
hereinafter in the case of conflict.
Prior to the commencement of grading, a geotechnical consultant (Consultant) shall be
employed for the purpose of observing earthwork procedures and testing the fills for
substantial conformance with the recommendations of the Geotechnical Report and these
specifications. It will be necessary that the Consultant provide adequate testing and
observation services so that he may determine that, in his opinion, the work was performed
in substantial conformance with these specifications. It shall be the responsibility of the
Contractor to assist the Consultant and keep him apprised of work schedules and changes
so that personnel may be scheduled accordingly.
It shall be the sole responsibility of the Contractor to provide adequate equipment and
methods to accomplish the work in accordance with applicable grading codes or agency
ordinances, these specifications and the approved grading plans. If, in the opinion of the
Consultant, unsatisfactory conditions such as questionable soil materials, poor moisture
condition, inadequate compaction, adverse weather, and so forth, result in a quality of work
not in conformance with these specifications, the Consultant will be empowered to reject
the work and recommend to the Owner that construction be stopped until the unacceptable
conditions are corrected.
2. DEFINITIONS
Owner shall refer to the owner of the property or the entity on whose behalf the grading
work is being performed and who has contracted with the Contractor to have grading
performed.
Contractor shall refer to the Contractor performing the site grading work.
Civil Engineer or Engineer of Work shall refer to the California licensed Civil Engineer
or consulting firm responsible for preparation of the grading plans, surveying and verifying
as-graded topography.
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2.4.
2.5.
2.6.
2.7.
3.1.
Consultant shall refer to the soil engineering and engineering geology consulting firm
retained to provide geotechnical services for the project.
Soil Engineer shall refer to a California licensed Civil Engineer retru,ned by the Owner,
who is experienced in the practice of geotechnical engineering. The Soil Engineer shall be
responsible for having qualified representatives on-site to observe and test the Contractor's
work for conformance with these specifications.
Engineering Geologist shall refer to a California licensed Engineering Geologist retained
by the Owner to provide geologic observations and recommendations during the site
grading.
Geotechnical Report shall refer to a soil report (including all addenda) which may include
a geologic reconnaissance or geologic investigation that was prepared specifically for the
development of the project for which these Recommended Grading Specifications ar~
intended to apply.
3. MATERIALS
Materials for compacted fill shall consist of any soil excavated from the cut areas or
imported to the site that, in the opinion of the Consuitant, is suitable for use in cqnstruction
of fills. In general, fill materials can be classified as soil fills, soil-rock fills or rock fills, as
defined below.
3.1.1. Soil fills are defined as fills containing no rocks or hard lumps greater than 12
inches in maximum dimension and containing at least 40 percent by weight of
material smaller than 3/4 inch in size.
3.1.2. Soil-rock fills are defined as fills containing no rocks or hard lumps larger than 4
feet in maximum dimension and containing a sufficient matrix of soil fill to allow
for proper compaction of soil fill around the rock fragments or hard lumps as
specified in Paragraph 6.2. Oversize rock is defined as material greater than 12
inches.
3.1.3. Rock fills are defined as fIlls containing no rocks or hard lumps larger than 3 feet
in maximum dimension and containing little or no fines. Fines are defined as
material smaller than 3/4 inch in maximum dimension. The quantity of fines shall
be less than approximately 20 percent of the rock fill quantity.
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3.2.
3.3.
3.4.
3.5.
3.6.
4.1.
Material of a perishable, spongy, or otherwise unsuitable nature as determined by the
Consultant shall not be used in fills.
Materials used for fill, either imported or on-site, shall not contain hazardous materials as
defined by the California Code of Regulations, Title 22, Division 4, Chapter 30, Articles 9
and 10; 40CFR; and any other applicable local, state or federa1laws. The Consultant shall
not be responsible for the identification or analysis of the potential presence of hazardous
materials. However, if observations, odors or soil discoloration cause Consultant to suspeCt
the presence of hazardous materials, the Consultant may request from the Owner the
termination of grading operations within the affected area. Prior to resuming grading
operations, the Owner shall provide a written report to the Consultant indicating that the
suspected materials are not hazardous as defined by applicable laws and regulations.
The outer 15 feet of soil-rock fill slopes, measured horizontally, should be composed of
properly compacted soil fill materials approved by the Consultant. Rock fill may extend to
. the slope face, provided that the slope is not steeper than 2: 1 (horizontal:vertical) a:pd a soil
layer lio thicker than 12 inches is track-walked onto the face for landscaping purposes. This
procedure may be utilized, provided it is acceptable to the governing agency, Owner and
Consultant.
Representative samples of soil materials to be used for fill shall be tested in the laboratory
by the Consultant to determine the maximum density, optimum moisture content, and,
where appropriate, shear strength, expansion, and gradation characteristics of the soil.
During grading, soil or groundwater con~itions other than those identified in the
Geotechnical Report may be encountered by the Contractor. The Consultant shall be
notified immediately to evaluate the significance of the unanticipated condition
4. CLEARING AND PREPARING AREAS TO BE FILLED
Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of
complete removal above the ground surface of trees, stumps, brush, vegetation, man-made
structures, and similar debris. Grubbing shall consist of removal of stumps, roots, buried
logs and other unsuitable material and shall be performed in areas to be graded. Roots and
other projections exceeding 1-112 inches in diameter shall be removed to a depth of 3 feet
below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to
provide suitable fill materials.
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4.2. Any asphalt pavement material removed during clearing operations should be properly
disposed at an approved off-site facility. Concrete fragments which are, free of reinforcing
steel may be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3
of this document.
4.3. After clearing and grubbing of organic matter or other unsuitable material, loose or porous
soils shall be removed to the depth recommended in the Geotechnical Report. The depth of
removal and compaction shall be observed and approved by a representative of the
Consultant. The exposed surface shall then be plowed or scarified to a minimum depth of 6
inches and until the surface is free from uneven features that would tend to prevent uniform
compaction by the equipment to be used.
4.4. Where the slope ratio of the original ground is steeper than 6: 1 (horizontal:vertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
Remove All
Unsuitable Material
As Recommended By
Soil Engineer
DETAIL NOTES:
Slope To Be Such That
Sloughing Or Sliding
Does Not Occur
Original Ground
Finish Slope Surface
. 1
See Note 2
No Scale
(1) Key width "B" should be a minimum of 10 feet wide, or sufficiently wide to
permit complete coverage with the compaction equipment used. The base of the
key should be graded horizontal, or inclined slightly into the natural slope.
(2) The outside of the bottom key should be below the topsoil or unsuitable surficial
material and at least 2 feet into dense formational material. Where hard rock is
exposed in the bottom of the key, the depth and configuration of the key may be
modified as approved by the Consultant.
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4.5.
5.1.
5.2.
6.1.
After areas to receive fill have been cleared, plowed or scarified, the surface sho\lld be
disced or bladed by the Contractor until it is uniform and free from large clods. The area
should then be moisture conditioned to achieve the proper moisture content, and compacted
as recommended in Section 6.0 of these specifications.
5. COMPACTION EQUIPMENT
Compaction of soil or soil-rock fill shall be accomplished by sheepsfoot or segmented-steel
wheeled rollers, vibratory rollers, multiple-wheel pneumatic-tired,rollers, or other types of
acceptable compaction equipment. Equipment shall be of such a design that it will be
capable of compacting the soil or soil-rock fill to the specified relative compaction at the
specified moisture content.
Compaction of rock fills shall be performed in accordance with Section 6.3.
6. PLACING, SPREADING AND COMPACTION OF FILL MATERIAL
Soil fill, as defined in Paragraph 3.1.1, shall be placed by the Contractor in accordance with
the following recommendations:
6.1.1. Soil fill shall be placed by the Contractor in layers that, when compacted, should
generally not exceed 8 inches. Each layer shall be spread evenly and shall be
thoroughly mixed during spreading to obtain uniformity of material and moisture
in each layer. The entire fill shall be constructed as a unit in nearly level lifts. Rock
materials greater than 12 inches in maximum dimension shall be placed in
accordance with Section 6.2 or 6.3 of these specifications.
6.1.2. In general, the soil fill shall be compacted at a moisture content at or above the
optimum moisture content as determined by ASTM DI557-00.
6.1.3. When the moisture content of soil fill is below that specified by the Consultant,
water shall be added by the Contractor until the moisture content is in the range
specified.
6.1.4. When the moisture content of the soil fill is above the range specified by the
Consultant or too wet to achieve proper compaction, the soil fill shall be aerated by
the Contractor by blading/mixing, or other satisfactory methods until the moisture
content is within the range specified.
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6.2.
6.1.5. After each layer has been placed, mixed, and spread evenly, it shall be thoroughly
compacted by the Contractor to a relative compaction of at least 90 percent:
Relative compaction is defined as the ratio (expressed in percent) of the in-place,
dry density of the compacted fill to the maximum laboratory dry density as
determined in accordance with ASTM DI557-00. Compaction shall be continuous
over the entire area, and compaction equipment shall make sufficient passes so that
the specified minimum relative compaction has been achieved throughout the
entire fill.
6.1.6. Soils having an Expansion Index of greater than 50 may. be used in fills if placed at
least 3 feet below finish pad grade and should 'be compacted at a moisture content
generally 2 to 4 percent greater than the optimum moisture content for theniaterial.
6.1.7. Properly compacted soil fill shall extend to the design surface of fill slopes. To
achieve proper compaction, it is recommended that fill slopes be over-built .by at
least 3 feet and then cut to the design grade. This procedure is consid~ted
preferable to track-walking of slopes, as described in the following parawaph.
6.1.8. As an alternative to over-building of slopes, slope faces may be back-rolled with a
heavy-duty loaded sheepsfoot or vibratory roller at maximum 4-foot fill height
intervals. Upon completion, slopes should then be track-walked with a D-8 dozer
or similar equipment, such that a dozer track covers all slope surfaces at least
twice.
Soil-rock fill, as defined in Paragraph 3.1.2, shall be placed by the Contractor in accordance
with the following recommendations:
6.2.1. Rocks larger than 12 inches but less than 4 feet in maximum dimension may be
incorporated into the compacted soil fill, but shall be limited t6 the area measured
15 feet minimum horizontally from the slope face and 5 feet below finish grade or
3 feet below the deepest utility, whichever is deeper.
6.2.2. Rocks or rock fragments up to 4 feet in maximum dimension may either be
individually placed or placed in windrows. Under certain conditions, rocks or rock
fragments up to 10 feet in maximum dimension may be placed using similar
, "
methods. The acceptability of placing rock 'materials greater than 4 feet, in
maximum dimension shall be evaluated during grading as specific cases arise and
shall be approved by the Consultant prior to placement.
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6.3,
6.2.3. For individual placement, sufficient space shall be provided between rocks to allow
for passage of compaction equipment.
6.2.4. For windrow placement, the rocks should .be. placed in trenches excavated in
properly compacted soil fill. Trenches should be approximately 5 feet wide and 4
feet deep in maximum dimension. The voids around and beneath rocks shoulcJ be
filled with approved granular soil having a Sand Equivalent of 30 ot greater and
should be compacted by flooding. Windrows may also be placed utilizing an
"open-face" method in lieu of the trench procedure, however, this method should
first be approved by the Consultant.
6.2.5. Windrows should generally be parallel to each other and may be placed either
parallel to or perpendicular to the face of the slope depending on the site geometry.
The minimum horizontal spacing for windrows shall be 12 feet center-to-center
with a 5-foot stagger or offset from lower courses to next overlying course. The
minimum vertical spacing between windrow courses shall be 2 feet from the top of
a lower windrow to the bottom of the next higher windrow.
6.2.6. All rock placement, fill placement and flooding of approved granular soil in the
windrows must be continuously observed by the Consultant or his representative.
Rock fills, as defined in Section 3.1.3., shall be placed by the Contractor in accordance with
the following recommendations:
6.3.1. The base of the rock fill shall be placed on a sloping surface (minimum slope of 2
percent, maximum slope of 5 percent). The surface shall slope toward suitable
sub drainage outlet facilities. The rock fills shall be provided with subd}."ains during
construction so that a hydrostatic pressure buildup does not develop. The subdrains
shall be permanently connected to controlled drainage facilities to control post--
construction infiltration of water.
6.3.2. Rock fills shall be placed in lifts not exceeding 3 feet. Placement shall be by rock
trucks traversing previously placed lifts and dumping at the edge of the currently
placed lift. Spreading of the rock fill shall be by dozer to facilitate seating of the
rock. The rock fill shall be watered heavily during placement. Watering shall
consist of water trucks traversing in front of the current rock lift face and spraying
water continuously during rock placement. Compaction equipment with
compactive energy comparable to or greater than that of a 20-ton steel vibratory
roller or other compaction equipment providing suitable energy to achieve the
required compaction or deflection as recommended in Paragraph 6.3.3 shall be
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utilized. The number of passes to be made will be determined as described in
Paragraph 6.3.3. Once a rock fill lift has been covered with soil fill, no ad.ditional
rock fill lifts will be permitted over the soil fill.
6.3.3. Plate bearing tests, in accordance with ASTM D1196-93, may be performed in
both the compacted soil fill and in the rock fill to aid in determining the number of
passes of the compaction equipment to be performed. If performed, a minimum ~f
three plate bearing tests shall be performed in the properly compacted soil fill
(minimum relative compaction of 90 percent). Plate bearing. tests· shall then be
performed on areas of rock fill having two passes, four passes and six passes of the
compaction equipment, respectively. The number of passes required for the rQok
fill shall be determined by comparing the results of the plate bearing tests for the
soil fill and the rock fill and by evaluating the deflection variation with number of
passes. The required number of passes of the compaction equipment will be
performed as necessary until the plate bearing deflections are equal to or less than
that determined for the properly compacted soil fill. In no case will the required
number of passes be less than two.
6.3.4. A representative of the Consultant shall be present during rock fill operations to
verify that the minimum number of "passes" have been obtainec;l, that water is
being properly applied and that specified procedures are being followed. The actual
number of plate bearing tests will be determined by the Consultant during grading.
In general, at least one test should be performed for each approximately 5,000 to
10,000 cubic yards of rock fill placed.
6.3.5. Test pits shall be excavated by the Contractor so that the Consultant can state that,
in his opinion, sufficient water is present and that voids between large rocks_ are
properly filled with smaller rock material. In-place density testing will not be
required in the rock fills.
6.3.6. To reduce the potential for "piping" of fines into the rock fill from overlying soil
fill material, a 2-foot layer of graded filter material shall be placed above the
uppermost lift of rock fill. The need to place graded filter material below the rock
should be determined by the Consultant prior to commencing grading. The
gradation of the graded filter material will be determined at the time the rock fill is
being excavated. Materials typical of the rock fill should be submitted to the
Consultant in a timely manner, to allow design of the graded filter prior to the
commencement of rock fill placement.
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7.1.
7.2.
7.3.
7.4.
6.3.7. All rock fill placement shall be continuously observed during placement by
representatives of the Consultant.
7. OBSERVATION AND TESTING
The Consultant shall be the Owners representative to observe and perform tests during
clearing, grubbing, and filling and compaction operations. In general, no more than 2 feet
in vertical elevation of soil or soil-rock fill shall be placed without at least one field density
test being performed within that interval. In addition, a minimum of one field density test
shall be performed for every 2,000 cubic yards of soil or soil-rock fill placed and
compacted.
The Consultant shall perform random field density tests of the compacted soil or soil-rock
fill to provide a basis for expressing an opinion as to whether the fill material is compacted
as specified. Density tests shall be performed in the compacted materials below any
disturbed surface. When these tests indicate that the density of any layer of fill or portion
thereof is below that specified, the particular layer or areas represented by the test shall be
reworked until the specified density has been achieved.
During placement of rock fill, the Consultant shall verify that the minimum number of
passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant shall
request the excavation of observation pits and may perform plate bearing tests on the
placed rock fills. The observation pits will be excavated to provide a basis for expressing
an opinion as to whether the rock fill is properly seated and sufficient moisture has been
applied to the material. If performed, plate bearing tests will be performed randomly on the
surface of the most-recently placed lift. Plate bearing tests will be performed to provide a
basis for expressing an opinion as to whether the rock fill is adequately seated. The
maximum deflection in the rock fill determined in Section 6.3.3 shall be less than-the
maximum deflection of the properly compacted soil fill. When any of the above criteria
indicate that a layer of rock fill or any portion thereof is below that specified, the affected
layer or area shall be reworked until the rock fill has been adequately seated and sufficient
moisture applied.
A settlement monitoring program designed by the Consultant may be conducted in areas of
rock fill placement. The specific design of the monitoring program shall be as
recommended in the Conclusions and Recommendations section of the project
Geotechnical Report or in the final report of testing and observation services performed
during grading.
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7.5.
7.6.
8.1.
8.2.
The Consultant shall observe the placement of subdrains, to verify that the drainage devices
have been placed and constructed in substantial conformance with project specifications.
Testing procedures shall conform to the following Standards as appropriate:
7.6.1. Soil and Soil-Rock Fills:
7.6.1.1. Field Density Test, ASTM D1556-00, Density of Soil In-Place [Jy the
Sand-Cone Method.
7.6.1.2. Field Density Test, Nuclear Method, ASTM D2922-96, Density of Soil and
Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).
7.6.1.3. Laboratory Compaction Test, ASTM D1557~OO, Moisture-Density
Relations of Soils and Soil-Aggregate Mixtures Using IO-Pound Hammer
and 18-Inch Drop.
7.6.1.4. Expansion Index Test, ASTM D4829-95, Expansion Index Test.
7.6.2. Rock Fills
7.6.2.1. Field Plate Bearing Test, ASTM D1196-93 (Reapproved 1997) Standard
Method for Nonreparative Static Plate Load Tests of Soils and Flexible
Pavement Components, For Use in Evaluation and Design of Airport and
Highway Pavements.
8. PROTECTION OF WORK
During construction, the Contractor shall properly grade all excavated surfaces to provide
positive drainage and prevent ponding of water. Drainage of surface water shall be
controlled to avoid' damage to adjoining properties or to finished work on the site. The
Contractor shall take remedial measures to prevent erosion of freshly graded areas nntil
such time as permanent drainage and erosion control features have been installed. Areas
subjected to erosion or sedimentation shall be properly prepared in accordance with the
Specifications prior to placing additional fill or structures.
After completion of grading as observed and tested by the Consultant, no further
excavation or filling shall be conducted except in conjunction with the services of the
Consultant.
GI rev. 07/02
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9.1.
9.2.
9. CERTIFICATIONS AND FINAL REPORTS
Upon completion of the work, Contractor shall furnish Owner a certification by the Civil
Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of
elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot
horizontally of the positions shown on the grading plans. After installation of a section of
sub drain, the project Civil Engineer should survey its location and prepare an as-built plan
of the subdrain location. The project Civil Engineer should verify the proper outlet for the
subdrains and the Contractor should ensure that the drain system is free of obstructions.
The Owner is responsible for furnishing a final as-graded soil and geologic report
satisfactory to the appropriate governing or accepting agencies. The as-graded report
should be prepared and signed by a California licensed Civil Engineer experienced in
geotechnical engineering and by a California Certified Engineering Geologist, indicating
that the geotechnical aspects of the grading were performed in substantial conformance
with the Specifications or approved changes to the Specifications.
GI rev. 07/02
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LIST OF REFERENCES
1. Blake, T. F., EQFAULT, A Computer Program for the Deterministic Prediction of Peak
Horizontal Acceleration from Digitized California Faults, Users Manual, 1989a, p. 79
(Revised 2000).
2. Tan, S.S. and Kennedy, M.P., Geologic Maps of the Northwestern Part of San Diego County,
California, 1996.
3. Seed, H. B. and Idriss, I. M., Ground Motions and Soil Liquefaction During Earthq14Qkes:
EERI Monograph Series, Berkeley, California, 1982.
4 United States Department of Agriculture, 1953 Stereoscopic Aerial Photographs, . Flight
AXN-BM, Photo Nos. 71 and 72.
5 United States Geological Survey, 7.5 minute Quadrangle Series, Encinitas Quadrangle, 1967,
photorevised 1975.
6 Unpublished reports, aerial photographs, and maps on file with Geocon Incorporated ..
Project No. 07431-22-01 December 16, 2004