HomeMy WebLinkAboutCT 08-03; LA COSTA TOWN SQUARE; GEOTECHNICAL INVESTIGATION; 2012-08-10I
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SOUTHERN CALIFORNIA
SOIL & TESTING, INC.
A CaUfornla Cer~illed :;maU Bllsines. Et\te 'p,ise [S6E)
San Diego 6280 Riverdale Street
619.281l.4321 San Oiego,CA 92120
Indio 83.14\1 Citrus Avenue
760.775.5983 Suite G
Indio, CA: '92201.3438
RiversIde 1130 palmytlta Avenue
951.965.8711 Suite 3300A
Riverside. CA 9250'1
Toll Free
S17.215.4321 www.scst.com
GEOTECHNICAL INVESTIGATION
LA COSTA TOWN SQUARE
RESIDENTIAL EAST DEVELOPMENT
CARLSBAD, CALIFORNIA
PREPARED FOR:
MR. RICK HENDERSON
PROPERTY DEVELOPMENT CENTERS
5918 STONERIDGE MALL ROAD
PLEASANTON, CALIFORNIA 94588
PREPARED BY:
SOUTHERN CALIFORNIA SOIL & TESTING, INC.
6280 RIVERDALE STREET
SAN DIEGO, CALIFORNIA 92120
Providing Professional Engineering Services Since 1959
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SOUTHERN CALIFORNIA
SOIL &TESTINGTINC.
A Californi. Certified Small Business Enterprise (SSE)
March 23, 2012
Revised August 10,2012
. Mr. Rick Henderson
Property Development Centers
5918 Stoneridge Mall Road
Pleasanton, California 94588
Subject: GEOTECHNICAL INVESTIGATION
LA COSTA TOWN SQUARE
RESIDENTIAL EAST DEVELOPMENT
CARLSBAD, CALIFORNIA
Dear Mr. Henderson:
San Diego 628(fRiverdale Street
619.280.4321 San Diego, CA 92120
Indio 83-740 Citrus Avenue
760.775.5983 Suite G
Indio, CA 92201-3438
Riverside 1130 Palmyrita Avenue
951.965.8711 -Suite 330.A
Riverside, CA 92507
Toll Free
877 .215.4321 www.scst.com
SCS&T No. 1111196
Report No.1 R
This letter transmits Southern California Soil & Testing Inco's (SCS&T) report describing the
updated geotechnical investigation performed for the planned east residential subdivision. The
subdivision will be located at the northeast corner of Rancho Santa Fe Road and La Costa
Avenue in the City of Carlsbad, California.
This investigation was conducted in general conformance with the scope of work -presented in
SCS& T's proposal dated November 16, 2011. If you have any questions concerning this repor:t.
or need additional information, please call us at (619) 280-4321.
Respectfully Submitted,
SOUTHERN CALIFORNIA SOIL AN~~.).:. •
Shih-Hsun Liang (Eddie
Staff Engineer
G8F:AKN:aw
(8) Mark Langan
(1) Mr. Mark Langan via e-mail atmarkl@sca-sd.com
(1) Mr. Rick Henderson via e-mail atrick.henderson@pdcenters.com
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TABLE OF CONTENTS
SECTION PAGE
EXECUTIVE SUMMARY ........................................................................................................................ I
1. INTRODUCTION ............................................................................................................................... 1
1.1 GENERAL ......................................................................................•...•........................•..•................ 1
1.2 SCOPE OF WORK. .............................•.............................................................................................. , 1
1.2.1 Field Exploration .................................................................................................................. 1
1.2.2 Laboratory Testing ................................................................................................................ 1
1.2.3 Analysis and Report .............................................................................................................. 1
2. SITE AND SUBSURFACE CONDITIONS ..................................................................................... 2
2.1 SITE DESCRIPTION .......................................................................•••..•................•.•....•..................... 2
2.2 STOCKPILE .............................................................................................•.............•...•..................... 2
2.3 SUBSURFACE CONDITIONS ...................................•...................•.....•..................•............................ 2
2.4 GROUNDWATER ............................................................................................................................. 3
2.5 POTENTIAL GEOLOGIC HAZARDS ................................•................................................••.•.•.•..... , .... 3
2.6 SEISMIC DESIGN PARAMETERS .........................................................•.............................•...•.......... 3
3. CONCLUSIONS ................................................................................................................................. 4
4. RECOMMENDATIONS ..................................................................................................................... 4
4.1 SITE PREPARATION AND GRADING ..............................................•............................•..•.................• 4
4.1.1 Site Preparation ............................... '" .................. '" ............................................................. 4
4.1.2 Compressible Soil Removal .................................................................................................. 4
4.1.3 Excavation Characteristics ................................................................................................... 5
4.1.4 Expansive Soil ....................................................................................................................... 5
4.1.5 Rock Fill Placement .............................................................................................................. 5
4.1.6 Lot Over'-Excavation Requirements ...................................................................................... 6
4.1.7 Earthwork ............................................................................................................................. 6
4.1.8 Keyway .................................................................................................................................. 6
4.1.9 Subdrains .............................................................................................................................. 6
4.1.10 Fill Slopes ............................................................................................................................. 7
4.1.11 Permanent Cut Slopes ........................................................................................................... 7
4.1.12 Temporary Excavation Slopes .............................................................................................. 7
4.1.13 Shrinkage and Bulkage Estimates ......................................................................................... 7
4.1.14 Imported Soil ......................................................................................................................... 8
4.1.15 Surface Drainage .................................................................................................................. 8
4.1.16 Grading Plan Review ............................................................................................................ 8
4.2 FOUNDATIONS ............................................................................................................................... 8
4.2.1 Conventional Footings .......................................................................................................... 8
4.2.2 Post-Tension Footings .......................................................................................................... 9
4. 2.3 Foundation Excavation Observations ................................................................................. 10
4.2.4 Static Settlement Characteristics ........................................................................................ 10
4.2.5 Resistance to Lateral Loads ................................................................................................ 1 0
4.2. 6 Foundation Plan Review ..................................................................................................... 10
4.3 SLABS-ON-GRADE ........................................................................................................................ 10
4.3.1 Interior Concrete Slabs-on-Grade ...................................................................................... 10
4.3.2 Exterior Concrete Slabs-on-Grade ..................................................................................... 11
4.4 EARTH RETAINING WALLS ................................................................ , .......................................... 12
4. 4.1 Foundations ........................................................................................................................ 12
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TABLE OF CONTENTS (Continued)
SECTION PAGE
4.4.2 Passive Pressure ................................................................................................................. 12
4.4.3 Active Pressure ................................................................................................................... 12
4.4.4 At-Rest Pressure .................................................................................................................. 12
4.4.5 Seismic Earth Pressure ....................................................................................................... 12
4.4.6 Waterproofing and Backdrain Observation ........................................................................ 13
4.4. 7 Backfill ................................................................................................................................ 13
4.4.8 Factor of Safety ................................................................................................................... 13
4.5 MSE WALL DESIGN PARAMETERS ................................................................................................ 13
TABLE 4 ..........................................................••..•...............•......•..................••..•..........•.......•.................... 13
4.6 PAVEMENT SECTION RECOMMENDATIONS .................................................................................. 13
TABLE 5 .................................................................................................................................................... 14
5. GEOTECHNICAL ENGINEERING DURING CONSTRUCTION ............................................ 14
6. CLOSURE ......................................................................................................................................... 14
TABLES
Table 1 ................................................... : ...................................... Expansion :Index Requirements
Table 2 .................................................................... Estimated Shrinkage and Bulkage Estimates
Table 3 ................................................... Pr~liminary Post -Tensioned Design Recommendation
Table 4 ..................................................... Mechanically Stabilized Earth Wall D~sign Parameters
Table 5 .............................................................................. Flexible Pavement Recommendations
ATTACHMENTS
FIGURES
Figure 1 ............................................................................................................... Site Vicinity Map
Figure 2 .......................................................................................... Subsurface Investigation Map
Figure 3 .............................................................................................. Grading Consideration Map
Figures 4 and 5 .......................................................................... Oversize Rock Placement Detail
Figure 6 ................................................................................................................ Subdrain Detail
Figure 7 ...................................................................................................... Wall Backdrain Details
APPENDICES
Appendix 1 ............................................................................... Logs of Exploratory Test Trenches
Appendix II ....................................................................................................... Laboratory Testing
Appendix III ........................................................................................... Seismic Traverse Results
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EXECUTIVE SUMMARY
This report presents the results of the geotechnical investigation Southern California Soil and
Testing, Inc. (SCS& T), performed for the planned subdivision to be located on the northeast
corner of Rancho Santa Fe Road and La Costa Avenue in the City of Carlsbad, California. The
purpose of our work is to provide conclusions and recommendations regarding the geotechnical
aspects of the project.
An SCS& T geologist observed the excavation of 4 exploratory test trenches to depths of
between 5 feet and 13 feet below the existing grade with a rubber tire backhoe equipped with an
18-inch bucket. The backhoe encountered refusal in test trenches, T-1 and T-2. SCS&T tested
selected samples from the trenches to evaluate pertinent classification and engineering
properties and assist in the development of geotechnical conclusions and recommendations.
Additionally, 9 seismic traverses where performed to determine rippability characteristics of the
underlying materials.
Materials encountered in the test trenches consist of alluvium, Delmar Formation, and
metavolcanic rock. The alluvium is comprised of loose, clayey sand and soft, sandy clay. The
Delmar Formation is comprised of very stiff to hard, sandy claystone. The metavolcanic ,rock is
comprised of metamorphosed and un-metamorphosed volcanic and sedimentary rock
commonly identified as. the Santiago Peak Volcanics. SCS&T's geologist observed
groundwater seepage and wet soil in test trench T-3.
The main geotechnical considerations affecting the planned development are:
• The presence of compressible alluvial materials;
• Expansive soils;
• Difficult excavation conditions;
• Cut/fill transitions below the building pads;
• Oversize materials.
Test trenches, T-1 and T-2 encountered refusal with a rubber-tire backhoe. The seismic
traverses indicate that the rock on-site will require blasting and specialized rock breaking
equipment during excavation. The on-site soil tested has a high expansion potential. We
expect that the excavated rock will need to be processed with expansive soil to produce a .
suitable fill material. Processing of the rock is expected to consist of crushing and/or screening.
Other alternatives to produce a suitable fill material can also be considered. Shallow spread
footings with bottom levels in compacted fill can be used for the support of the planned
structures.
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1. INTRODUCTION
1.1 GENERAL
This report presents the results of the geotechnical inv~stigation Southern California Soil and
Testing, Inc. (SCS&T), performed for the planned subdivision to be located on the northeast
corner of Rancho Santa Fe Road and La Costa Avenue in the City of Carlsbad, California. We
understand the structures will be of wood frame construction. The purpose of our work is to
provide conclusions and recommendations regarding the geotechnical aspects of the project.
Figure 1 presents a site vicinity map.
1.2 SCOPE OF WORK
1.2.1 Field Exploration
Subsurface conditions were explored by excavating a total of 4 exploratory tesUrenches to
depths of between 5 feet and 13 feet below the existing grade with a rubber tire backhoe
equipped with an 18-inch bucket. Additionally, 9 seismic traverses where performed to
determine the rippability characteristics of the underlying materials. Figure 2 shows the
locations of the test trenches and seismic traverses. An SCS& T geologist logged the test
trenches and obtained samples for examination and laboratory testing. The logs of the test
trenches are in Appendix I. Soils are classified according to the Unified Soil Classification
System illustrated on Figure 1-1. The seismic traverse results are in Appendix III.
1.2.2 Laboratory Testing
The laboratory program consisted of tests for:
• Atterberg limits;
• Grain size distribution;
• Expansion Index.
The results of the laboratory tests, and brief explanations of test procedures, are in
Appendix II.
1.2.3 Analysis and Report
SCS& T evaluated the results of the field and laboratory tests to develop conclusions and
recommendations regarding:
1. Subsurface conditions beneath the site;
2. Site preparation;
3. Excavation characteristics;
4. Potential geologic hazards that may affect the site;
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Property Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
August 10,2012
SCS& T Proposal No. 1111196-01 R
Page 2
5. Criteria for seismic design in accordance with California Building Code procedures;
6. Appropriate alternatives for foundation support along with geotechnical engineering
criteria for design of the foundations;
7. Resistance to lateral loads;
8. Estimated foundation settlements;
9. Support for concrete slabs-on-grade floors;
10. Lateral pressures for the design of retaining walls;
11. Pavement sections.
2. SITE AND SUBSURFACE CONDITIONS
2.1 SITE DESCRIPTION
The subject site is an irregular shaped lot located on the northeast corner of Rancho Santa Fe
Road and La Costa Avenue in the City of Carlsbad, California: The site is bounded by vacant
land on the west, Rancho Santa Fe Road on the north, an SDG&E power line easement on the
northeast, and La Costa Avenue and a residential subdivision on the southeast side. A
stockpile of rocks is located at the northwestern portion of the project area. The site is located
along a south-facing slope that is characterized by four north-south trending, natural drainage
swales that flow to the south. The total elevation difference of the site is about 170 feet over a
span of 2,000 feet. Vegetation consists of native grasses and shrubs.
2.2 STOCKPILE
A stockpile is located at the northwest corner of the site. The material observed in the stockpile
consists of clayey soils and rocks that range up to about 4 feet in maximum dimension. This
material was most likely derived from excavations performed as part -of the construction of
Rancho Santa Fe Road and nearby developments. The stockpile appears to be about 20 feet
thick at it deepest section and is most likely underlain by metavolcanic rock.
2.3 SUBSURFACE CONDITIONS
Alluvium, Delmar Formation, and metavolcanic rock underlie the subject site. Figure 2 shows
the approximate limits of the geologic materials.
Alluvium: SCS& T's geologist observed alluvium comprised of loose clayey sand and soft
sandy clay with gravel in test trenches T-1 through T-3. In general, this material is located
within the drainage swales at the site. This alluvium encountered in our test trenches
extended to depths of between about 2 feet and 7 feet below the ground surface and
overlies the Delmar Formation or metavolcanic rock.
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Properly Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
August 10, 2012
SCS& T Proposal No. 1111196-01 R
Page 3
Delmar Formation: SCS&T's geologist observed the Delmar Formation comprised of very
stiff to hard, sandy claystone at the surface in test trench T-4 and below the alluvium in test
trench T-3. This material extended to the maximum depth explored of 13 feet in test trench
T-3.
Metavolcanic Rock: SCS& T's geologist observed Metavolcanic rock below the alluvium in
test trenches T-1 and T-2. The metavolcanic rock is typically comprised of metamorphosed
and un-metamorphosed volcanic and sedimentary rock commonly identified as the Santiago
Peak Volcanics. This material extended to the maximum depth explored of 6 feet in test
trench T-1.
2.4 GROUNDWATER
SCS&T's geologist observed groundwater seepage in test trench T-3. Water cmd wet soil should
be expected at the bottoms of the existing alluvial channels. Groundwater levels can fluctuate
seasonally, and can rise significantly following periods of precipitation. In addition, -groundwater
can be perched on impermeable layers of the claystone and/or rock as a result of rainfall and
irrigation.
2.5 POTENTIAL GEOLOGIC HAZARDS
No known geologic hazards are mapped at the site. A geologic hazard likely to affect the
project is groundshaking as a result of movement along an active fault zone in the vicinity of the
subject site.
2.6 SEISMIC DESIGN PARAMETERS
The site coefficients and adjusted maximum considered earthquake spectral response
acceleration parameters in accordance with the 2010 California Building Code based on the
2009 International Building Code are presented below:
Site Coordinates: Latitude 33.083°
Longitude -117.229°
Site Class: D
Site Coefficient Fa = 1.056
Site Coefficient Fv = 1.583
Spectral Response Acceleration at Short Periods Ss = 1.1
Spectral Response Acceleration at 1-Second Period S1 = 0.4
SMs=FaSs
SM1=FvS1
SDs=2/3* SMS
SD1=2/3* SM1
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Property Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
3. CONCLUSIONS
August 10,2012
SCS&T Proposal No. 1111196-01R
Page 4
The main geotechnical considerations affecting the planned development are:
• The presence of compressible materials;
• Expansive soils;
• Difficult excavation conditions;
• Cut/fill transitions below the building pads;
• Oversize materials.
Test trenches, T-1 and T-2 encountered refusal with a rubber-tire backhoe. The seismic
traverses indicate that the rock on-site will require blasting and specialized rock breaking
equipment during excavation. The on-site soil tested has a high expansion potential. We
expect that the excavated rock will need to be processed with the expansive soil to produce a
suitable fill material. Processing of the rock is expected to include crushing and/or screening.
Other alternatives to produce a suitable fill material can also be considered. Shallow spread
footings with bottom levels in compacted fill can be used for the support of the planned
structures.
4. RECOMMENDATIONS
4.1 SITE PREPARATION AND GRADING
4.1.1 Site Preparation
Site preparation should begin with the removal of the existing vegetation and debris. It is
expected that the upper 6 inches of the exposed surface will need to be brushed and
exported from the site. The stockpile of soil and existing fill, if any, should be excavated in
their entirety.
4.1.2 Compressible Soil Removal
It is recommended that existing compressible soils (fill, alluvium and highly weathered
formational deposits) underlying areas of the site to be graded be excavated in their entirety.
SCS& T expects the compressible soil excavation to be about 3 feet within the alluvial
drainage channels. No excavation for remedial grading is expected outside of the channels
where rock is exposed on the surface. Figure 3 presents the approximate limits of the
compressible soil removal. An SCS& T representative should observe conditions exposed in
the bottom of the excavation to determine if additional excavation is required.
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Property Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
4.1.3 Excavation Characteristics
August 10,2012
SCS& T Proposal No. 1111196-01 R
PageS
Conventional heavy equipment in good working order is expected to be able to excavate the
alluvial materials on-site. However, non-rippable rock exists on-site, and these areas will
require rock-breaking equipment. In addition, oversized, buried hard rock requiring special
handling should be anticipated. Contract documents should specify that the contractor
mobilize equipment capable of excavating and breaking the bedrock.
Additionally, it should be noted that gravel, cobbles, and boulders up to 48 inches in
diameter could be encountered within the stockpile. Contract documents should specify that
the contractor mobilize equipment capable of compacting materials with gravel and cobbles.
4.1.4 Expansive Soil
The existing materials on-site that were tested have a high expansion potential in
accordance with ASTM D4829. Table 1 presents expansion index recommendations for the
placement of the soil.
Table 1
E Id R xpanslon n ex eqUiremen ts
Depth Below Planned Final Grade Expansion Index of Material to be Placed
Elevation
Cut lots Expansion Index Less than 50
o to 10 feet Expansion Index Less than 90
Greater than 10 feet Expansion Index Greater Than 90 Allowed'
4.1.5 Rock Fill Placement
The quantity of rock generated during grading operations will depend on the grading
scheme. The rock will most likely consist of cobbles and boulders' of varying size. The rock
should be mixed with sufficient quantities of soil such that nesting does not occur during
placement and the rock is completely surrounded by a soil matrix material. The rock/soil
mixture should be placed in lifts of approximately 12 inches in thickness and compacted with
a rubber-tire loader. Oversized rock between 6 inches and 2 feet may be placed in structural
fills in accordance with the details illustrated in the attached Figures 4 and 5. Larger rock
may only be utilized for landscaping purposes. Rocks greater than 3 inches in diameter
should not be used within 18 inches of final grade or where foundation or utility trenches will
be located.
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Property Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
4.1.6 Lot Over-Excavation Requirements
August 10, 2012
SCS& T Proposal No. 1111196-0fR'
Page 6
Hard rock is expected to be encountered at the planned final grade elevation for the lots
located along the north side of the site. The remainder of the lots will span a cut/fill
transition with fill differential ranging between about 5 and 20 feet. Figure 3 presents the
expected over-excavation requirements for each lot. The depths shown may have to be
increased depending on the final grading. The bottoms of the excavation and subgrades
beneath fill areas should be sloped toward the street or fill portion of the lot, and .away from
its center.
4.1.7 Earthwork
The material exposed in the bottom of the excavation should be scarified to a depth of 12
inches, moisture conditioned and compacted to at least 90% relative compaction. Excavated
materials, except for soil containing roots and organic debris, can be used as compacted fill.
Fill should be placed in 6-to 8-inch thick loose lifts, moisture conditioned to near optimum
moisture content, and compacted to at least 90% relative compaction. The maximum dry
density and optimum moisture content for the evaluation of relative compaction should be
determined in accordance with ASTM D 1557.
Utility trench backfill within 3 feet of the structure and beneath pavements and hardscape
should be compacted to a minimum of 90% relative compaction. The upper 12 inches of
subgrade beneath slabs and paved areas should be compacted to at least 95% relative
compaction.
4.1.8 Keyway
A keyway shall be established at the base of sloped areas. The keyway should be at least
15 feet wide at the bottom, extend at least 3 feet into competent material·and be sloped
back at an inclination of about 2%. The keyway may need to be wider to accommodate
compaction equipment. Final keyway recommendations will depend on the final grading
plans.
4.1.9 Subdrains
Canyon subdrains shall be installed at the bottom of canyon removals wherever fill depths
exceed 10 feet. Canyon subdrains should consist of a perforated pipe (SDR 35 or
equivalent), surrounded by at least 6 cubic feet per lineal foot of crushed rock wrapped in
filter fabric (Mirafi 140N or equivalent). A canyon subdrain is presented on Figure 6. As-
graded canyon subdrain locations should be surveyed.
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Property Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
August 10, 2012
SCS& T Proposal No. 1111196-01 R
Page 7
Subdrains may be required at the heel of keyways for buttress slopes and/or fill-over-cut
slopes, Figure 6. Subdrains may also be required for some transition undercut areas if
warranted by soil conditions or the presence of groundwater. Figure 3 shows the
approximate locations of the planned subdrains.
4.1.10 Fill Slopes
Fill slopes can be constructed at an inclination of 2:1 (horizontal:vertical). Compaction of
slopes should be performed by back-rolling with a sheepsfoot compactor at vertical intervals
of 2 feet or less as the fill is being placed, and by track-walking the face of the slope when
the fill is completed. Alt~rnatively, slopes can be overfilled and cut back to expose dense
material at the design line and grade. Fills should be benched into temporary slopes and
. into the rock when the natural slope is steeper than 5:1 (horizontal:vertical).
4.1.11 Permanent Cut Slopes
It is our opinion that cut slopes, constructed at an inclination of 2:1 or flatter, ratio will
possess an adequate factor of safety. The engineering geologist should observe all cut
slopes during grading to ascertain that no unforeseen adverse conditions requiring revised
recommendations are encountered.
4.1.12 Temporary Excavation Slopes
It is recommended that temporary cut slopes, greater than 3 feet in depth, be cut at an
inclination no steeper that 1: 1. Cuts less than or equal to 3 feet in depth can be made
vertical. Temporary cut slopes should be observed by an SCS&T Engineering Geologist
during grading to ascertain that no unforeseen adverse conditions are observed. The
temporary slopes should be inspected daily by the contractor's Competent Person before
personnel are allowed to enter the excavation. Zones of potential instability, sloughing or
raveling should be brought to the attention of the Engineer and corrective action
implemented before personnel begin working in the trench. No surcharge loads should be
placed within a distance from the top of temporary cut slopes equal to half the slope height.
4.1.13 Shrinkage and Bulkage Estimates
The estimate shrinkage and bulkage estimates are presented below.
Table 2
Sh . k rm age an dB Ik Eft u age sima es
Soil Type Shrinkage Bulkage.
Topsoil and alluvium 15% to 20%
Del Mar Formation 5% to 10%
Metavolcanic Rock 10% to 20%
Rock Stockpile 15% to 20%
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Property Development Centers
La Costa Town Square Residential East Development
Carlsbad, California
4.1.14 Imported Soil
August 10, 2012
SCS& T Proposal No. 1111196-01 R
Page 8
Imported fill should meet the specifications for Caltrans structure backfill and, if appropriate,
be tested by SCS& T prior to transport to the site.
4.1.15 Surface Drainage
Final surface grades around the buildings should be designed to collect and di~~ct surface
water away from the structure and toward appropriate drainage facilities. The ground around
the structures should be graded so that surface water flows rapidly away from the structure
without ponding. In general, we recommend that the ground adjacent to the structure slope
away at a gradient of at least 2%. Densely vegetated areas where runoff can be impaired
should have a minimum gradient of at least 5% within the first 5 feet from the structure. Roof
gutters with downspouts that discharge directly into a closed drainage system are
recommended on structures.
Drainage patterns established at the time of fine grading should be maintained throughout
the life of the proposed structures. Site irrigation should be limited to the minimum
necessary to sustain landscape growth. Should excessive irrigation, imp~ired drainage, or
unusually high rainfall occur, saturated zones of perched groundwater can develop.
4.1.16 Grading Plan Review
The grading plans should be submitted to SCS& T for review to ascertain whether the intent
of the recommendations contained in this report have been implemented, and that no
revised recommendations are necessary due to changes in the development scheme.
4.2 FOUNDATIONS
4.2.1 Conventional Footings
Residential structures and retaining walls can be supported on shallow spread footings with
bottom levels in compacted fill. A minimum width of 12 inches is recommended for
continuous footings for single story structures and 15 inches for 2 story structures. Isolated
footings should be at least 24 inches wide. All footings should extend a minimum of 18
inches below lowest adjacent grade for pads with an expansion index less than 50. All
footings should extend a minimum of 24 inches below lowest adjacent grade for pads with
an expansion index less than 90. A bearing capacity of 2,500 pounds per square foot (psf)
can be used. These values can be increased by % when considering the total of all loads,
including wind or seismic forces. Footings adjacent to slopes should be extended to a depth
such that a minimum distance of 7 feet exists between the bottom of the footing and the face
of the slope. For conventional retaining walls, a minimum 10-foot distance is ,recommended.
1(1'
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4.2.2 Post-Tension Footings
August 10, 2012
SCS&T Proposal No. 1111196-01R
Page 9
Shallow spread footings with bottom levels in compacted fill can be ·used to support the
planned structures. The slab should be designed by a structural engineer familiar with the
design criteria presented in the Post-Tensioning Institutes (PTI), Third Edition, as required
by the 2010 CSC, Section 1805.8. The post-tensioned design should incorporate the
geotechnical parameters presented below.
Table 3
Preliminary Post -Tensioned Design Recommendations
Post-Tensioning Institute (PTI), Third Recommended Design Parameters Edition Design Parameters
Thornwaite Index -20
Equilibrium Suction 3.9
Edge Lift Moisture Variation Distance, em (feet) 4.7
Edge Lift, Ym (inches) 1.10
Center Lift Moisture Variation Distance, em (feet) 9.0
Center Lift, Ym (inches) 0.47
Pre-saturation, as needed, to obtain the minimum 1.3 times optimum down to 18 inches moisture down to minimum depth
Subgrade Modulus, k (pounds per cubic inch) 50
A minimum width of 12 inches is recommended for continuous footings for single story
structures and 15 inches for two story structures. Isolated footings should be at least 24
inches wide. All footings should extend a minimum of 24 inches below lowest adjacent
grade. All footings should extend a minimum of 18 inches below lowest adjacent grade for
pads with an expansion index less than 50. All footings should extend 'a minimum of 24
inches below lowest adjacent grade for pads with an expansion index less than 90. A
bearing capacity of 2,500 pounds per square foot (psf) can be used. These values can be
increased by % when considering the total of all loads, including wind or seismic forces.
Footings adjacent to slopes should be extended to a depth such that a minimum distance of
7 feet exists between the bottom of the footing and the face of the slope.
Experience indicates post-tensioned slabs are susceptible to excessive edge lift, regardless
of the underlying soil conditions. Placing reinforcement at the bottom of the perimeter
footings and the interior stiffener beams may mitigate this potential. The structural engineer
should design the foundation system to reduce the potential edge lift occurring for the
planned structures.
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August 10, 2012
SCS& T Proposal No. 1111196-01 R
. Page 10
SCS& T should be contacted to provide final post-tension recommendations after grading is
complete.
4.2.3 Foundation Excavation Observations
It is recommended that all foundation excavations be approved by a representative from
SCS& T prior to forming or placing reinforcing steel.
4.2.4 Static Settlement Characteristics
Total footing settlements are estimated to be less than 1 inch. Differential settlements
between adjacent footings are estimated to be less than % inch. Settlements should occur
rapidly, and should be completed shortly after structural loads are applied.
4.2.5 Resistance to Lateral Loads
Lateral loads will be resisted by friction between the bottoms of the footings and passive
pressure on the faces of footings and other structural elements below grade. A friction
factor of 0.3 can be used. Passive pressure can be computed using a lateral pressure value
of 300 psf per foot of depth below the ground surface. The upper foot of soil should not be
relied on for passive support unless the ground is covered with pavements or slabs.
4.2.6 Foundation Plan Review
The foundation plans should be submitted to SCS& T for review to ascertain that the inteht of
the recommendations in this report has been implemented and that revised
recommendations are not necessary due to the layout.
4.3 SLABS-ON-GRADE
4.3.1 Interior Concrete Siabs-on-Grade
Concrete slabs-on-grade should be designed by the project structural engineer. Siabs-on-
grade should be underlain by a 4-inch thick blanket of clean, poorly graded, coarse sand
(sand equivalent = 30 or greater) or %-inch crushed rock. Where moisture sensitive floor
coverings are planned, a vapor retardant should be placed over the s.and layer. An
additional 2 inches of sand can be placed over the vapor retardant to provide a degree of
protection during construction. Typically, visqueen is used as a vapor retardant. If visqueen'
is used, a minimum 10-mil is recommended.
Moisture emissions can vary widely, depending upon such factors as concrete type and
subgrade moisture conditions. If these moisture emission values are not within the
manufacturer's specifications for the type of flooring to be installed, SCS& T should be
contacted to develop appropriate additional damp-proofing recommendations. It is
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SCS& T Proposal No. 1111196-01 R
Page 11
recommended that moisture emission tests be performed prior to the placement of floor
coverings. In addition, over-watering should be avoided, and good site drainage should be
established and maintained to reduce the potential for the build-up of excess sub-slab
moisture.
4.3.2 Exterior Concrete Siabs-on-Grade
Exterior slabs should have a minimum thickness of 4 inches and should be reinforced with
at least No.3 bars at 18 inches on center each way. Additionally slabs should be underlain
by at least 6 inches of aggregate base. Slabs should be provided with weakened plane
joints. Joints should be placed in accordance with the American Concrete Institute (ACI)
Guidelines Section 3.13. Joints should be placed where cracks are anticipated to develop
naturally. Alternative patterns consistent with ACI guidelines also can be used. The
landscape architect can be consulted in selecting the final joint patterns.
A 1-inch maximum size aggregate mix is recommended for concrete for exterior slabs. A
water/cement ratio of less than 0.6 is recommended, in order to decrease the potential for
shrinkage cracks. It is strongly suggested that the driveway concrete mix have a minimum
compressive strength of 3,000 pounds per square inch (psi). Coarse and fine aggregate in
concrete should conform to the "Greenbook" Standard Specifications for Public Works
Construction.
Special attention should be paid to the method of curing the concrete to reduce the potential
for excessive shrinkage and resultant random cracking. Minor cracks occur normally in
concrete slabs and foundations due to shrinkage during curing and redistribution of
stresses. Some shrinkage cracks can be expected. These cracks are not necessarily an
indication of vertical movements or structural distress.
Factors that contribute to the amount of shrinkage that takes place in a slab-on-grade
include joint spacing, depth, and design; concrete mix components; water/cement ratio and
surface finishing techniques. According to the undated 'Technical Bulletin" published by the
Southern California Rock Products Association and Southern California Ready Mixed
Concrete Association, flatwork formed of high-slump concrete (high water/cement ratio)
utilizing 3/8-inch maximum size aggregate ("Pea Gravel Grout" mix) is likely to exhibit
extensive shrinkage and cracking. Cracks most often occur in random patterns between
construction joints.
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4.4 EARTH RETAINING WALLS
4.4.1 Foundations
August 10,2012
SCS&T Proposal No. 1111196-01R
Page 12
The recommendations provided in the foundation section of this report are also applicable to
. earth retaining structures.
4.4.2 Passive Pressure
The passive pressure for the retaining walls can be considered to be 300 psf per foot of
depth up to a maximum of 1 ,500 psf. This pressure may be increased by % for seismic
loading. The coefficient of friction for concrete to soil may be taken as 0.3 for resistance to
lateral movement. When combining friction and passive resistance, the friction should be
reduced by %. The upper 12 inches of soil in front of retaining wall footings should not be
included in passive pressure calculations unless pavement extends adjacent to the footing.
4.4.3 Active Pressure
The active soil pressure for the design of unrestrained earth retaining structures with level
backfills can be taken as equivalent to the pressure of a fluid weighing 40 pounds per cubic
foot (pcf). An additional 20 pcf should be added for walls with sloping backfills of
2:1 (horizontal:vertical) or flatter. A granular and drained backfill condition has been
assumed. Surcharge loads from vehicles can be taken into account by assuming an
additional 2 feet of soil is supported by the wall. If any. other surcharge loads are anticipated,
SCS& T should be contacted for the necessary increase in soil pressure. The project
architect should provide. waterproofing specifications and' details. A typical wall backdrain
detail is shown on Figure 7.
4.4.4 At-Rest Pressure
The at-rest soil pressure for the design of restrained earth retainin~ structures with level
backfills can be taken as equivalent to the pressure of a fluid weighing 60 pet. An additional
20 pet should be added for walls with sloping backfills of 2:1 (horizontal:vertical) or flatter. A
granular and drained backfill condition has been assumed. If any surchar!;le loads are
anticipated, SCS& T should be contacted for the necessary increase in soil pressure.
4.4.5 Seismic Earth Pressure
The seismic earth pressures can be taken as an inverted triangular distribution with a
maximum pressure at the top equal to 16H pounds per square foot (with H being the height
of the retained earth in feet). This pressure is in addition to the un-factored static design
wall load. The allowable passive pressure and bearing capacity can be increased by % in
determining the stability of the wall.
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SCS& T Proposal No. 1111196-01 R
Page 13
4.4.6 Waterproofing and Backdrain Observation
The geotechnical engineer should be requested to verify that waterproofing has been
applied and that the backdrain has been properly installed. However, unless specifically
asked to do so, we will not verify proper application of the waterproofing. SCS& T does have
a waterproofing division that can provide this service if requested.
4.4.7 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 grout has reached an adequate strength.
4.4.8 Factor of Safety
The above values, with the exception of the allowable soil bearing pressure, do not include a
factor of safety. Appropriate factors of safety should be incorporated into the design.
4.5 MSE WALL DESIGN PARAMETERS
The following soil parameters can be used for the design of Mechanically Stabilized Earth
(MSE) walls.
Table 4
Mechanically Stabilized Earth Wall Design Parameters
Reinforced Soil .Retained Soil Foundation Soil
Internal Friction Angle 30° 30° 30° (degrees)
Cohesion 0 0 0 (pounds' per square foot)
Moist Unit Weight (pounds 130 130 130
per cubic foot)
4.6 PAVEMENT SECTION RECOMMENDATIONS
The pavement support characteristics of the soils encountered during our investigation range
from poor to good. It is anticipated that these deposits will be mixed and the resulting blend will
have moderately good pavement support characteristics. An "R" value of 25 was assumed for
this blend. The actual "R" value of the subgrade soils will be determined after grading. Based
on an "R" value of 25, the following structural sections are recommended for the assumed
Traffic Indices.
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Table 5
August 10, 2012
SCS& T Proposal No. 1111196-01 R
. Page 14
Flexible Pavement Recommendations
Traffic Index Asphalt Concrete Aggregate Base 1
(inches) (inches)
6.0 4 9
7.5 5 12 .. Note 1: AB shall conform to Class 2 Aggregate Base m Section 26·1.02 of the Standard Specifications of The
State of California Department of Transportation or Crushed Miscellaneous Base in accordance with the
Standard Specifications for Public Works and City of Carlsbad Standards.
Bus turnouts should be constructed in accordance with the San Diego Regional Standard
Drawings SDG-109, 9 inches of concrete underlain by at least 12 inches of aggregate base.
The concrete should have a compressive strength of at least 3250 pounds per square inch.
SDG&E concrete maintenance areas should have a concrete thickness of at least 7~ inches
underlain by at least 12 inches of aggregate base.
Trash enclosures should have a thickness of at least 7~ and be underlain by at least 12 inches
of aggregate base.
The upper 12 inches of subgrade should be scarified, moisture conditioned to above optimum
moisture requirements, and compacted to at least 95% of the maximum dry density. All soft or
spongy areas should be excavated and replaced with compacted fill. The base material should
be compacted to at least 95% of its maximum dry density. All materials and methods of
construction should conform to good engineering practices and the minimum standards set forth
by the City of Carlsbad.
5. GEOTECHNICAL ENGINEERING DURING CONSTRUCTION
The geotechnical engineer should review project plans and specifications prior to bidding and
construction to check that the intent of the recommendations in this report has been
incorporated. Observations and tests should be performed during construction. If the
conditions encountered during construction differ from those anticipated based on the
subsurface exploration program, the presence of the geotechnical engineer during construction
will enable an evaluation of the exposed conditions and modifications of the recommendations
in this report or development of additional recommendations in a timely manner.
6. CLOSURE
SCS& T should be advised of any changes in the project scope so that the recommendations
contained in this\ report can be evaluated with respect to the revised plans. Changes in
recommendations will be verified in writing. The findings in this report are valid as of the date of
this report. Changes in the condition of the site can, however, occur with the passage of time,
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August 10,2012
SCS& T Proposal No. 1111196-01 R
Page 15
whether they are due to natural processes or work on this or adjacent areas. In addition,
changes in the standards of practice and government regulations can occur. Thus, the findings
in this report may be invalidated wholly or in part by changes beyond our control. This report
should not be relied upon after a period of two years without a review by us verifying the
suitability of the conclusions and recommendations to site conditions at that time.
In the performance of our professional services, we comply with that level of care and skill
ordinarily exercised by members of our profession currently practicing under similar conditions
and in the same locality. The client recognizes that subsurface conditions may vary from those
encountered at the boring locations, and that our data, interpretations, and recommendations
are based solely on the information obtained by us. We will be responsible for those data,
interpretations, and recommendations, but shall not be responsible for interpretations by others
of the information developed. Our services consist of professional consultation and observation
only, and no warranty of any kind whatsoever, express or implied, is made or intended in
connection with the work performed or to be performed by us, or by our proposal for consulting
or other services, or by our furnishing of oral or written reports or findings.
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SOUTHERN CALIFORNIA
SOIL & TESTING, INC.
SITE VICINITY MAP
LA COSTA TOWN SQUARE -
RESIDENTIAL EAST Scale:
1111196-1
Not To Scale 1
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~--------------------------------------~~~
OVERSIZE ROCK FILL PLACEMENT
ZONED
ZONE A: Compacted soil fill.
No rock fragments over 3 inches in any dimension.
ZONE B: Compacted soil fill.
No rock fragments over 6 inches in any dimension.
ZONE C: No rock fragments over 2 feet in any dimension.
Uniformly distributed and well spaced in compacted soil fill.
ZONE D: No rock fragments over 4 feet in any dimension.
Uniformly distributed and well spaced in compacted soil fill.
Note 1: Compacted soil fill should contain at least 40% soil finer than ~ inch
sieve (by Weight) and be compacted to at least 90% relative
compaction.
Note 2: Rocks over 4 feet in maximum dimension are not permitted in fill.
Date: 8/9/2012 Figure: By: EL 4 Job No.: 1111196-1 R
Scale: Not To Scale Revised
OVERSIZE ROCK DISPOSAL C_ SOUTHERN CALIFORNIA
~SOIL & TESTING, INC. LA COSTA TOWN SQUARE -
RESIDENTIAL EAST
-------------------
:0
NOTES:
Typical Windrow Detail (End View)
Typical Windrow Q€)tail (Profile View)
OVERSIZE ROCK DISPOSAL
(Structral Soil -Rock Fill)
'---P/L .1
~~~~~~~~~~~~~ "~i~~~Z;;~,:S~2~t~~ii;t.;.yr .:::~ ~~~:;,I:j;~~;;:··t~.f~:
.:;.<t.,:-t -.... --~ .....-..,.,. r-"\~ ~~ ~~ . '>.y" 3 5' MIN ~~ .. " ZO~~B\~QCr..qcr~QQ'QO( 1 I /J~ 11 0 ° 01 0 0 0 n ~-=OOOO=a~o=S o~ , .. .:-..:">-';/0 (1'.=' ° 0 0 5)f~tG»1~ 0 0 0 0 ZONECO 0 0 0 0 0 0 0 0 0 <
. ~'~'~"'YZONE 0 r-..c:.. ~-Ci.:. .b =--0...:. Q.=-O _0-= 0 -:-...S) -=-~ c-0 (
4'M1N l .~.~ Q/ 0 0 ZONED 0 O~
:::I.... . / 0 0 ~!L J!~ -LEGEND
ZONEE ZONE A: Compacted soil fill.
No rock fragments over 3 inches in any dimension.
ZONE B: Compacted soil fill.
No rock fragments over 6 inches in any dimension.
ZONE C: No rock fragments over 2 feet in any dimension. . I.. ..I 12' MIN 3'MIN
Uniformly distributed and well spaced in compacted soil fill.
1. Compacted soil fill shall contain at least 40% soil size passing ~ inch
sieve, (by weight), and be compacted at least 90% relative compaction.
2. Rocks over 4 feet in maximum dimension not permitted in fill.
ZONE D: No rock fragments over 4 feet in any dimension.
Uniformly distributed and well spaced in compacted soil fill.
ZONE E: Required for all existing slopes 5:1 and steeper, At least 90%
comapction Zone A or B material can be used.
11 cO'
Date: 8/9/2012
~. 01 (J)
e ...... (j)
.C_ SOUTHERN CALIFORNIA
~SOIL & TESTING, INC.
OVERSIZE ROCK DISPOSAL
LA COSTA TOWN SQUARE -
RESIDENTIAL EAST
By:
Job No.:
EL
1111196-1 R
Not To Scale (j)
Q. Scale:
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Natural
Ground
CANYON SUBDRAIN DETAIL
Remove
Unsuitable
Material
Ir-------------------------------~-
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D ET AI L A Perforated Pipe Surrounded with Filter Material
Detail
A-1
Filter Material
6 cubic feet/foot
Perforated Pipe* Detail
A-2
DETAIL B ! inch open-graded gravel
wrapped in filter fabric (Mirafi
140N or equivalent)
Detail
B-1
Filter Material
-(Mirafi 140N or approved equivalent)
Perforated Pipe*
i inch open graded
gravel or equivalent
6 cubic feet/foot
I I
Detail
B-2
(for fills
over 35'
deep)
Filter Material Shall be Class 2
permeable material per Section 68 of
CAL TRANS standard specifications, or
approved alternate.
DETAIL of Canyon
Subdrain Outlet
Filter Fabric
======:;:===
11-201
MIN" b: MI~ I r Non-perforated Pipe* -I" Perforated PiPe*-I
I r-----------------~----~--------SUBDRAIN INSTALLATION
I Subdrain pipe shall be installed with perforation down. * MINIMUM DIAMETER
SUBDRAIN PIPE 4" min = 0 -500' Drain.
Subdrain pipe shall be PVC or ABS, type SDR35 for fills up 6" min = 500 -1,000' Drain 1r-__ to_3_5_f_e_et_d_e_e_p_,o_r_t_yp_e_S_D_R,2_1_f_o_r_fil_ls_u_P_t_o_1_00 __ fe_e_t_de_e_p_. __ -r ________ B_"m __ in_= __ 1_,0_O~O~+~D_r_ai_n __ ~
I -SUBDRAIN DETAIL C_ SOUTHERN CALIFORNIA
~SOIL & TESTING, INC. LA COSTA TOWN SQUARE-
RESIDENTIAL EAST I~----~------~----~~
Date: 1/1/2012 Figure: By: El
Job No.: 1111196-1 6 Scale: Not To Scale
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. min.
/
/
/
/
/
/
/
/ ,r:;I-----+---Miradrain 6000 or Equivalent
1 -Filter fabric between rock and soil.
2 -Backcut as recommended in accordance with CALOSHA
3 -Waterproof back of wall. .
4 - A 4-inch minmum diameter perforated pipe, SDR35 or equivalent, holes
1 % fall to outlet, encased in 3/4" crushed rock. Provide 3 cubic feet per
lineal foot of crushed rock minimum. Crushed rock to be surrounded
by filter fabric (Mirafi 140N or equivalent), with a 6-inch minumum
overlap. Provide solid outlet pipe at suitable location.
5 -3/4-inch crushed rock
I~----~----~------~~
I ,, __ SOUTHERN CALIFORNIA
<li-SOIL & TESTING, INC.
WALL BACKDRAIN Date:
By:
LA COSTA TOWN SQUARE -Job No.:
RESIDENTIAL EAST
8/10/2012
GBF/EL
1111l96-1R
Figure:
7 Scale: NOTIOSCALE I ~ L-.---___ --L----__ -----'-___ ----,.--'--------'
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APPENDIX I
FIELD INVESTIGATION
APPENDIX I
Four exploratory test trenches were excavated at the locations shown on Figure 2. The
fieldwork was performed under the observation of our geology personnel, who also logged the
trenches and obtained samples of the materials encountered.
The test trench logs are presented on Figures 1-2 through 1-5. Soils are classified in accordance
with the Unified Soil Classification System illustrated on Figure 1-1.
I
SUBSURFACE EXPLORATION LEGEND
I UNIFIED SOIL CLASSIFICATION CHART
SOIL DESCRIPTION GROUP TYPICAL NAMES SYMBOL
I. COARSE GRAINED, more than 50% of material is larger than No. 200 sieve size. I
GRAVELS CLEAN GRAVELS GW Well graded gravels, gravel-sand mixtures, little or no fines More than half of
coarse fraction is GP Poorly graded gravels, gravel sand mixtures" little or no fines. larger than No.4
I
sieve size but GRAVELS WITH FINES GM Silty gravels, poorly graded gravel-sand-silt mixtures. smaller than 3". (Appreciable amount of I·
fines) GC Clayey gravels, poorly graded gravel-sand-clay mixtures.
SANDS CLEAN SANDS SW Well graded sand, gravelly sands, little or no fines. More than half of I
coarse fraction is SP Poorly graded sands, gravelly sands, little or no fines. smaller than No.
4 sieve size. SANDS WITH FINES SM Silty sands, poorly graded sand and silty mixtures. I
(Appreciable amount of
I fines) SC Clayey sands, poorly graded sand and clay mixtures.
II. FINE GRAINED, more than 50% of material is smaller than No. 200 sieve size.
SILTS AND CLAYS ML Inorganic silts and very fine sands, rock flour, sandy silt Of clayey-silt-
(Liquid Limit less sand mixtures with slight plasticity. I
than 50) CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays,
silty clays, lean clays.
OL Organic silts and organic silty clays of low plasticity. I
SILTS AND CLAYS MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils,
(Liquid Limit elastic silts.
greater than 50) CH Inorganic clays of high plasticity, fat clays. I
I OH Organic clays of medium to high plasticity. .
III. HIGHLY ORGANIC SOILS PT Peat and other highly organic soils.
I FIELD SAMPLE SYMBOLS LABORATORY TEST SYMBOLS
IZ/-Bulk Sample AL -Atterberg Limits
CAL -Modified California penetration test sampler CON -Consolidation
CK -Undisturbed chunk sample COR -Corrosivity Test
MS -Maximum Size of Particle -Sulfate I
6~ -Chloride -Water seepage at time of excavation or as indicated -pH and Resistivity
SPT -Standard penetration test sampler DS -Direct Shear I
ST -Shelby Tube EI -Expansion Index
V -Water level at time of excavation or as indicated MAX -Maximum Density
RV -RValue
SA -Sieve Analysis I
UC -Unconfined Compression
~ SOUTHERN CALIFORNIA LA COSTA TOWN SQUARE RESIDENTIAL EAST
{.s~ SOIL & TESTING, INC. By: DAS I Date: 1/3/2012
~~ Job Number: 1111196-1 I Figure: 1-1
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Date Excavated:
Equipment:
LOG OF TEST PIT NUMBER T-1
12/8/2011 Logged by: AKN
Project Manager: GBF
Surface Elevation (ft):
Case 580L with 18-inch bucket
377 Depth to Water (ft): not observed
g
:c Cf) I-0 0... Cf) W ::l o
SUMMARY OF SUBSURFACE CONDITIONS·
ALLUVIUM (Qal) -Medium brown, moist, loose, CLAYEY
"-cC-", SAND.
'"
sc
'-2 '-------------------------------------------------------------------Mottled medium and dark brown, moist, soft, SANDY CLAY.
I-4
(contact at 4 % feet)
METAMORPHOSED AND UNMETAMORPHOSED
'-6 ~ VOLCANIC AND SEDIMENTARY ROCKS, UNDIVIDED
\
(Mzu) -Light brown and medium reddish brown,
moderately weathered, very hard, and intensely fractured.
I-8
BOTTOM OF TEST TRENCH AT 6 FEET. NO
I-10 GROUNDWATER OR SEEPAGE ENCOUNTERED.
-12
I-14
-16
-18
SAMPLES
C
0 ..-. CJ
:::R 0.. >-W ~ ---a::: co W ~ OCf) a::: ~ a::: ~I-::l ...J I-::l ::l I-a:::Cf)
Cf) co I-Z OW
£5 Cf) ::l col-
Z 0 >-« ::l 2 a::: ...J
0
r---
~
'-20~~----------------------------------------------------------------------------~----~~----~----~----~
~C.., SOUTHERN CALIFORNIA
(S~! SOIL & TESTING, INC.
~-~
LA COSTA TOWN SQUARE RESIDENTIAL EAST
By: AKN Date: 8/10/2012
Job Number: 1111196-1 Figure: 1-2
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LOG OF TEST PIT NUMBER T-2
Date Excavated: 12/8/2011 logged by: AKN
Equipment: Case 580l with 18-inch bucket Project Manager: GBF
Surface Elevation (ft): 372 Depth to Water (ft): not observed
SAMPLES
c
0 ~ u -0.. >-~ W ~ '-" 0::
00 c:o W ~ ~oo :c () 0:: ~ I-00 SUMMARY OF SUBSURFACE CONDITIONS ::J ....J 0:: «I-
a. ::J I-::J ::J I-0::00
W 00 c:o I-Z OW
0 Ci 00 c:o I-. (5 ::J Z >-« ::J :2: 0:: ....J
0
CL ALLUVIUM (Qal) -Medium brown, moist, soft, SANDY CLAY.
- 2
I-4 METAMORPHOSED AND UNMETAMORPHOSED -VOLCANIC AND SEDIMENTARY ROCKS1 UNDIVIDED
- 6
\ jMzu) -Light brown and medium reddish brown,
moderately weathered, very hard, and intensely fractured.
I-8 BOTTOM OF TEST TRENCH AT 5 FEET. NO
GROUNDWATER OR SEEPAGE ENCOUNTERED.
i-10
-12
I-14
-16
-18
-20
& SOUTHERN CALIFORNIA lA COSTA TOWN SQUARE RESIDENTIAL EAST
SOIL & TESTING, INC. By: AKN Date: 1/3/2012
Job Number: 1111196-1 Figure: 1-3
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LOG OF TEST PIT NUMBER T-3
Date Excavated: 12/8/2011 logged by: AKN
Equipment: Project Manager: GBF
Surface Elevation (ft):
Case 580l with 18-inch bucket
288 Depth to Water (ft): seepage at 5 feet
g
I C/)
I-() 0... C/) W ::::> o
SUMMARY OF SUBSURFACE CONDITIONS
CL ALLUVIUM (Qal) -Dark brown, very moist, soft, SANDY
CLAY.
r-2 I---+--------------------------------------~ DELMAR FORMATION (Td) -Light gray and light orange
- 4
- 6
r-8
-10
r-12
-16
r-18
brown, very moist, medium stiff to stiff, SANDYClAYSTONE.
.................................. 3 a Seepage encountered below 5 feet.
Becomes saturated below 5 feet.
Becomes very stiff to hard below 8 feet.
BOTTOM OF TEST TRENCH AT 13 FEET.
SAMPLES
o W co
0:: ~ ::::> -J I-::::> C/) co Ci z ::::>
~ r--
\/
II \
'--
c-.-.. ()
~ 0->--0::
W g 0 'I-C/) 0:: «l-::::> t: 0::C/) 1-. Z OW C/) col-O ::::> >-« :E 0:: -J
0
EI
~20~~--------------------------------------~--~~--~--~--~
~ SOUTHERN CALIFORNIA
(~~ SOIL & TESTING, INC. By:
lA COSTA TOWN SQUARE RESIDENTIAL EAST
1111196-1 Figure: Job Number:
AKN Date: 1/3/2012
1-4
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LOG OF TEST PIT NUMBER T-4
Date Excavated: 12/8/2011 logged by: AKN
Equipment: Project Manager: GBF
Surface Elevation (ft):
Case 580l with 18-inch bucket
300 Depth to Water (ft): not observed
.g
:c 00 I-() a.. 00 UJ ::>. o
- 2
- 4
-
- 6
'-8
-10
-12
-14
-16
-18
SUMMARY OF SUBSURFACE CONDITIONS
DELMAR FORMATION (Td) -Light gray and light orange
brown, moist, very stiff to hard, SANDY CLAYSTONE.
BOTTOM OF TEST TRENCH AT 5 FEET. NO
GROUNDWATER OR SEEPAGE ENCOUNTERED.
SAMPLES
o UJ cc cr: :::s::: ::> ..J I-::> 00 cc 0 z ::>
~I
1/\
f--
c-........ u
~ a. ~ 0 '-'
'-' ~ 0 00 UJ cr: 1-1-« 00' ::> I-I-Z cr:UJ
00 01-
(5 ::> cc
>-« :2 cr: ..J
0
Al,
SA
_20L-~ ______________________________________ ~ __ ~J-__ ~ __ ~ __ -...l
SOUTHERN CALIFORNIA
SOIL & TESTING, INC.
lA COSTA TOWN SQUARE RESIDENTIAL EAST
By: AKN Date: 1/3/2012
Job Number: 1111196-1 Figure: 1-5
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APPENDIX II
LABORATORY TESTING
SUMMARY
APPENDIX II
Laboratory tests were performed to provide geotechnical parameters for engineering analyses.
The following tests were conducted:
• CLASSIFICATION: Field classifications were verified in the laboratory by visual
examination. The final soil classifications are in accordance with the Unified Soil
Classification System.
• GRAIN SIZE DISTRIBUTION: A grain size distribution was determined for one sample
in accordance with ASTM D 422. The result of this test is presented on Figure /1-1.
• ATTERBERG LIMITS: The Atterberg limits were determined for one sample in
accordance with ASTM D 4318. The result of this test is presented on Figure /1-1.
• EXPANSION INDEX TESTS: One expansion index test was performed in accordance
with ASTM D 4289. The result of this test is presented on Figure 11-2.
Soil samples not tested are now stored in our laboratory for future reference and analysis, if
needed. Unless notified to the contrary, all samples will be disposed of 30 days from the date of
this report.
-------------------
u.s. Standard Sieve Sizes
I 6" 3" 1-'!h:" 3/4" 3/8'" #4 #8#10 #16 #30 #40#50 #100 #200
100 "-
90 ~ ....... ~
80 ~ .... -r--., ..c .~70 -----~ ~ ~60 ~ ... Q) ......... .: 50 u. .... t: B 40 ... Q) a.
30
20
10 !
0
1000 100 10 1 0.1 0.01
Grain Size in Millimeters
I Cobbles I Gravel I Sand I Silt or Clay I I Coarse I Fine I Coarse Medium I Fine I
I SAMPLE LOCATION I UNIFIED SOIL CLASSIFICATION: CL I ATTERBERG LIMITS
I T -4 between 0' and ~' I DESCRIPTION SANDY CLAY with Gravel I LIQUID LIMIT 50
pLASTIC LIMIT 22
PLASTICITY INDEX 28
C) SOUTHERN CALIFORNIA LA COSTA TOWN SQUARE RESIDENTIAL EAST ~ SOIL & TESTING, INC . . S~ By DAS I Date 1/3/12
Job Number 1111196 I Figure 11-1
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EXPANSION INDEX
ASTM -04829
I SAMPLE 1/ DESCRIPTION
"
EXPANSION INDEX I
T-3 at 0' to 2' I Medium brown, CLAYEY SAND· I 123
CLASSIFICATION OF EXPANSIVE SOIL
EXPANSION INDEX POTENTIAL EXPANSION ~~~~~~,~,~-~-~-~-~-~-~-~-~-~-~-~-~-~--o -20 Very Low
21 -50 Low
51 -90 Medium
91 -130 High
Above 130 Very High
By: DAS/GBF Date: 1/3/2012
n ;5 C SOUTHERN CALIFORNIA ~ s:.::il SOIL & TESTING, INC. ~
LA COSTA TOWN SQUARE RESIDENTIAL EAST
Job Number: 1111196-1 Figure: 11-2
I APPENDIX III
I
APPENDIX III
I SEISMIC TRAVERSE RESULTS
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SEIS:MIC REFRACTION SURVEY
LA COSTA TO'WlS" CENl'ER
CARLSBAD, CALIFORNJA
PRE'P ARE» VOR:
Southern California S9i1 &,'l'esting-
·6280 River4~Y ~treet.
San Diego, CA 92120
PREPARED "BY,:
Southwest Geophysics~ .Inc.
8057 Raytheon Road, Suite 9
San Diego, .CA .92111
Dec.ember 29 ~ 2011.
Projecd:~:o. flT:3:9.9
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4t~~~E;~:-
YOUR SU8SURFACE SOLUTION
Mr. Doug. Skinner
Southel11 California Soil & Testing
6280 Riverdale Street
San Diego, CA 92120
Subject: Seismic Refraction Survey
La Costa Town Center
Carlsbad, California
Dear Mr. Skinner:
7"?tr'n%z~ titr
December 29,2'011
. Project No. i11399
In accordance with your authorization, we have performed a seismic refraction survey p.ertainmg
to the proposed La Costa Town Center project located along Rap.cho Santa.Fe RQiil-4 in Gar1spad,
California. Specifically, our survey consisted of performing 10 seismic refraction lines at the
subject site. The purpose of the study was to develop sl,ibsuiface velocity profUes·ofthe project.
area and to evaluate the apparent rippabiliw of the shallow subsurface materials. This report pre.,
sents our survey methodology'\. equipment used, analysis, and results from our survey.
We appreciate the opportunity to be of service. on this project. Should you have arty.quesfions
related to this report, please contact the undersigned 'l:t your convt,(nience. .
Sincerely,
SOUTHWEST GEOPHYSICS, INC.
~~
'Patrick Lehrmann, P.G., R.Gp.
Principal Geologist/Geophysicist
HVIPFLlhv
Distribution: Addressee (electronic)
Hans van ·de Vmgt, C.RO.; :B..Gp.
PrinCipal GeolQgistiGeophysicist
8057 Raytheon Road, Suite 9 • San Diego' California 92111 • Telephone 858-527-0849 • Fax 858-225,0114.
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La Costa Town Center
Carlsbad, California
TABLE OF CONTENTS
December 29; ;2011
Proj~ct NQ. 111399
Page
1. INTRODUCTION ............................................................. , ........................ , ... , ............................ 1
2. SCOPE OF SERVICES .................... · .............................. " .............................................. " ............ 1
3, SITE AND PROJECT DESCRiPTION ......................... ,., .. , ...... ".".,." .. " .......................... , ........ i
4. SURVEY METHODOLOGY ......................................... , ............................... : ..... , .................. ~ ... 1
5. RESULTS ........................................................................... , ....................................... : ................. 3
6. CONCLUSIONS AND RECOl\1MENDATIONS ........... , ........................ ~ ... ; ............... , ......... "A
7. LIMITATIONS ........................................................................ ' ........... " ...................................... 5
8. SELECTED REFERENCES .................................................................... ' ..................... , ... " ... ,.6
Tables
Tabie 1-Rippability Classification ............................................. ' ................................................. < ••.••• , • .3.
Table 2 -Seismic Traverse Results ....................... _._ .. " .. " .. ~ ...................... ~ .... ~~ .............................. "., .. .3
-Site Location Map
Line Location Map
Figures
'Figure 1
Figure 2
Figure 3a -
'Figtrre 3b -
Figure 3c -
Figure4a -
Figure4b -
Figute4c -
Figure4d -
Figure 4e -
Site Photographs (SL-l to SL-4)
Site Photographs (SL-5 to SL-7)
Site Photographs (SL-8 to SL-IO)
Seismic Profiles, SL-l and SL-2
Seismic Profiles, SL-3 and SL-4
Seismic Profiles, SL-5 and SL-6
Seismic Profiles~ SL-7 and SL-g
Seismic Profiles, SL-9 and SL-IO
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La Costa Town Center
Carlsbad, California
1. INTRODUCTION
Decemb.er·29., 2011
Prqject.No.l1l399
In accordance with your authoiization~ we have performed a 'seismic refraction survey pert1rining
to the proposed La Costa Town Center project located .along Rancho Santa Fe Road ill Carlsbad"
California (Figur.e 1). Specifically, our survey 'consisted of performing 10 seismic refraction lines·
at the subject site. The purpose of the study was to develop subsurface velocity profiles of the
project area and to evaluate the apparent rippability of the shallow subsurface materials. This Ie;.
port presents our survey methodology, equipment used, analysis. and results. from our survey.
2. SCOPE OF SERVICES
.our scope of services for this study included:
• Performance of 10 seismic refraction lines at the project site.
• Compilation and analysis of the data collected.
• Preparation of this report presenting ourre~;ults, conclusions, mid recQi1WJ.end$tiulls.
3. SITE AND PROJECT DESCRIPTION
The study area is located along the south side of Rancho Santa Fe Road" near its intersection with
Paseo Lupino in the Carlsbad area of San Diego (Figure 1). The site is generally undeveloped
with the exception of a few dirt roads which transect the site. Topography cQnsists of relatively
gentle slopes. Vegetation consists of annual grass and bnlsh. Figures 2 arid 3a thrOl.tg,b 3;g depict
the general site conditions in the area of the refraction lines., It is our t}nderstanding that. r~si
dences. may be constructed at the site and thl:J.t cuts up to 45 feet inliY be. petfbtJ:i1edd~g
grading.
4. SURVEY METHODOLOGY
A seismic P-wave (compression wave) refraction survey-was Gondu'Cted at the site to e\Taluate thl:;
rippahility characteristics of the subsurface materials and to develop a subsurface. velocity profile,
of the site. The seismic refraction method uses first-arrival times of .refracted seismic waves to
estimate the thicknesses and seismic velocities of subsurface layers .. Seismic P-wavesgenerated
at the surface, using a hammer and plate~ ar~ refracted 'at boundaries s~paraiing matedals of con-
trasting velocities. These refracted seismic waves are. then detected by a.s.eries. ofsuifac~ vertical
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La Costa Town Center
Carlsbad, California
December 29, 2011
·Project.No. 1 i 1399
component geophones, and recorded with a 24-channel Geometrics Strata Vie:'N" -s:eismograph.
The travel times of the seismic P-waves are used in conjunction with the 5hot-to.,g~ophone dis-
tances to obtain thickness and velocity information on the subsurface materials.T en seismic.
lines/profiles (SL-l through SL-10) were coriducted .at the site as part of this study. Theap-
proximate locations of the lines are depicted on Figure 2,· Shot points (signal .generation
locations) were conducted at each end of the lin~ and at the midpoint. The Hiles. were 150 feet
long ~d the general locations were selected by your office.
The refraction method requires that subsurface velocities increase with depth. A layer having a
velocity lower than that of the layer above will generally not be· detectable by the· seismic rerrae,.
tion method and, therefore, could lead to errors in the depth calculations ofsubsequent layers, In
addition, lateral variations in velocity) such as those caused by core stones/outcrops, can . also re...;
suIt in the misinterpretation of the subsurface conditions.
In general, seismic wave velocities can be correlated to tnaterjaldenslo/ .and/6r tock har.dness,
The relationship between rippability ·and seismIC velocity is empjrica1 and 'assumes 'l;r 11Omgge-
neus mass. Localized areas of differing composition, texture, ~mdfor structure may affe'ct both the
measured data and the actual rippability of the mass .. The rippahility of a IUa~s js also dep;endeht
on the excavation equipment used and the skill and.experience of the equipmentep:erator.
The rippability values presented in Table 1 are based on .our experience with -similar materials'
and assumes that a Caterpillar D-9 dozer ripping with a 'sfugle shank is used. We empluis'ize that
the cU.toffs in this classification. scheJjle are approximate apd that tock thara;cteristics, :sl1ch 'as'
fracture spacing and OflentatioI}, p.lay a 'significant role in 4~teni:rihing r9,ck tippaOiiity. These'
'characteristics may also vary with location and depth.
For trenching operations, the rippability values shou14 pe scaled. downward. Bor example, veloci-
ties as low as 3,500 feet/second may indicate difficult ripping during trepching' operations.! Ih .
. addition, the presence of boulders, which can be troublesome in a narrow trench; :shQuld bea!}.-
ticipated.
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La Costa Town Center
Carlsbad, California
December 29~ 2011
Project No.: 111399
Table 1-Rippability Classification
SeismicP-wave Velocity Rippability·
o to 2,000 feet/second Easy
2,000 to 4,000 feet/second Moderate
4,000 to 5,500 feet/second Difficult"Possible Blastiiig
5,500 to 7,000 feet/second Very Difficult, Probable Blasting
Greater than 7,000 feet/second Blasting Genern;lly R{;lqtiir:ed
It should be noted that the rippab'ility cutoffs presented in Table 1 are slightly mOreC(:lIiservative
than those published in the Caterpillar Performance Handbook (Caterpillar, 2004). AccordingLy,
the above classification scheme should be used with discretion; and contractors should not be
relieved of making their own independent evaluation of therippabilityof the -on.,site materials
prior to submitting their bids.
5. RESULTS
Table 2 lists the average P-wave velocities and depths' calc;uhlted from the seismic ,fyfraction
traverses conducted dUri1lg our evaluation. Tbe approximate 10oatio11s-of the ,seis1l11G' refra,ction
traverses are shown on the Line Location Map (Figure 2). Layer velocity profiles .ate· also ip-
eluded in Figures 4a through 4e. Please note the vertical se'ale changes for the profiles. rt should
also be noted that, as a general rule, the. effective depth of evaluation for ,a seismic refraction
traverse is approximately one-third to one-fifth the length of the refraction 'line .. The lengths of
the seismic refraction lines are listed with their interpretations in Table 2.
Table .2 -Seismic Tr.averse Results
Traver~e No. P-wave Velocity Approximate Depth to Rippability* And Length feet/second Bottom ·ofLayer in feet
SL-l VI = 1,615 1-,5. Easy
150 feet V2=3,475 7-16 Moderate
V3:::: 6,795 ---VelY Difficult, .. Probable Blasting: .. ..
SL-2 VI = 1,355 12-19 Easy
150 feet V2 = 7,050 ---Blasting Generally'Required
SL-3 VI = 1,820 8-17 Easy
150 feet V2= 7,640 ---Bla,sting Generally Required
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La Costa Town Center
Carlsbad, California
December '29,2011
ProjectNo. 11139.9,
Table 2 -Seismic Traverse Results
Traverse No. P-wave Velocity Approximate Depth to Rippability* And Lengtb feet/second Bottom of Layer in feet
SL-4 VI = 1,325 12-17 Basy' ,.
150 feet V2 =6,115 ---Very Difficult, Probahle B18.&(mg
SL-5 VI ='1,310 16-19 Ba.sy-
150 feet V2 = 7,.190 ---Blasting Generally: Req uired
SL-o VI = 1,250 17...,21 Easy
150 feet V2=9,370 ---BlasnntrGeii.etally Required
SL-7 VI = 1,365 2i -28 Easy
150 feet V2 = 8,080 ---Blasting Generafly ReqlJired
SL-8 VI =1,395 '18 -27 Eaiy
150 feet V2 = 7,535 ---Blasting Generally Required
SL-9 VI = 1,215 1-$ "Ea1W
150 feet V2=3,500 12-22 Moderate
V3 = 8,770 ---Blasting Generally Required
SL-lO VI = 1,340 15-22 Ea$Y
150 feet V2= 10,960 ---BlastlngGenerallv Required .. Rippability criteria based on the usc of a Caterpillar D-9 dozer ripping with a single shank
6. CONCLUSIONS A.1'W RECOMMENDATIONS
The results from this seismic survey revealed two to three distinct geolQgiclayers at the locations
surveyed. Based on our site observations and discussions with you, the study area isgeneraUy
underlain by surficial soils (i.~., topsoil, colluvium, andlor fiU) and crystalline bedrock with vary-
ing degrees of weathering. The layer velocities measured for the surfiyiai layers are· generally
consistent; however, the bedrock velocities vary across ihe site.
Significant scatter was noted in the first-arrivals indicating the, presence of inhomogen.eities ~
the subsurface materials. These inhomo.geneities may·be due to buried core stonesltemnant boul."
ders, dikes, and/or differential weathering of the bedrock. Therefore., significant variability in the
excavatability (including excavation depth) of 'the subsurface materials should be expe,cted
across the project area. A contractor with excavation experience in simllar conditions ,should be
c<?nsulted for expert advice on excavation methodology, equipment,. production rate, 'and (>.\'er-
sized materials.
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La Costa Town Center
Carlsba,d~ California
7. LIMITATIONS
December 29, 2011
.Proje.ct No. 111399
The field ,evaluation and geophysical analyses presented in this report have b~ep' co.n9ucted in
,general accordance with current practice and the standard ·of care exerdse9,'by con,s\lltant$ p:er-
forming similar tasks in the project area. No warranty~ expressed or implied, is lIlade regarding,
the condusion~ recommendations, and opinions presented in this report. There is noeyah;t~1i9n
detailed enough to reveal every subsurface condition. Variations may' exist and conditions not
observed or described in this report may be present. Uncertainties relative' to subsurface condi ..
tions can be reduced through additional subsurface exploration. Additional subsurface surVeying
will be performed upon request.
This, document is intended to be used only in its entiretY. No PQrtion of the docuinettt; by itseJf, is'
designed to completely represent any aspect of the proje'ct described herejn. SQuthwes:t Ge9phys;-
1cs, Inc. should be contacted if the reader requires additional information or has, q'!le~tions
regarding the content, interpretations presented, or completeness of this document. This report is
intended exclusively for use by the client. Any use or reuse of the findings, conclusions, andior
recommendations of this report by parties other than the client is undertakeri a'tsaid parties~' sole
risk.
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La Costa Town Center
Carlsbad, California
8. SELECTED REFERENCES
December 29" 2011
ProjecfNo, 11 U99
Caterpillar" Inc., 2004, Caterpillar Performance Handbook.; Edition 3'5, Caterpillar, Inc~, Peoria,
Illinois.
Mooney, H.M., 1976, Handbook ofEngine.ering Geophysics, rlatE!d February.
Rimrock Geophysics, 2003, Seismic Refraction Interpretation Pwgrams (SIPwin), V.,,2.76.
Telford, W.M., Geldart, L.P., Sheriff, R.E., and Keys, D.A., 1976, Applied Oeophysics,Cam,-
bridge University Press.
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SITE LOeA TION MAP
La Costa Town Center
Carlsbad, California
Project No.: 111399 Date.: 1.211.1
rVlfuO
Golf·:
EmE;r:
at
SOUTHWEST
-G;EOPHVSICS INC.
Pigure 1
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'0
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(5 z: g
'/S' It
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I == Z
0 j::
~
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..oJ
W z
::::i
I
- -- - - -
SITE PHOTOGRAPHS
(SL-1 to Sl.:-4)
- - - -
La Costa Town center
Carlsbad, California
-
Pr oject No.: 1~1399 Dale: 12111,
- - - - -- - -
• II,; SOuTHWeST
............. ..-.--..,::UC!iIt-!c"
Figure3a
--------------
SITE PHOTOGRAPHS,
(SL-5, to SL-7)
La Costa'ToWn Genter
Carlsbad, California
Pro)ectNo.: 111399 p"le: 12Wl
'f' sourHWEST~,
rGaoP"'YS'C~'lNC,
Figure3b
- ----
--- ---
SITE PHOTOGRAPHS
($L-8 toSL-1 0)
- - - -
La CO!lt~. Town.Center
Carlsbad) Caiifornia
-
Projecll'lo.~ 1 :113~9· Qa\e: 1·2(1·1
-- -- - -- -
·K'SOUTHWEST _
9E::Qr··t-tV~I,,-,~.'NV<
FigtJre·3c
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I SL-1
Ii i I i i 1 i i i i i iii iii, f i-I I I I' I I i i I I 1.0
I 0
I ::: 0 :;:: -1.0 III > ell WE"
I eIl-> :;:: III -20 Q) c:::
I -'30
I -"10
0 20 40 60 80 1.00 1.20 1.40
I Distance
(ft)
SL-2
I i i • I i i i i 1 j i i ii' i i j i I j i I I J i I I i i I, I I 20
C
I B
I ::: 0 :;:: 0 III > ell w'iE'
I eIl-> :;:: III -1.0 Q) c:::
I -20
I -30
0 20 40 60 80 1.0Q 1.20 1.<10,
Distance
I (ft)
SEISMIC PROFILES La Costa Town Center ' SOUTHWEST
I SL-1 AND SL-2 Carlsbad, California' ~ GEOPHYSICS INC
Project No,: 111399 Date: 12/11 Figure 4a
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o 20
o 20
SEISMIC PROFILES
SL-3 AND SL-4
40
40
60
60
SL-3
80
Distance
(ft)
SL-4
80
Distance
(ft)
1:00
100
La Costa Town Center
Carlsbad, California
12.0
120
Project No.: 111399 Date: 12/11
140
SOUTHWEST
'GEOPHyslcs INC.
Figure 4b
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o 20
o 20
SEISMIC PROFILES
SL-5 AND SL-6
40
40
60
60
SL-5
80
Distance
(tt)
SL-6
80
Distance
(tt)
100
100
La Costa Town Center
Carlsbad, California
Project No.: 111399 O"te: 12/11
120 140
. ·e
o
"'10
120 140
'SOUTHWEST
Fi~ure 4c
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o 20
o 20
SEISMIC PROFILES
SL-7 AND SL-8
40
40
60
60
SL-7
'8.0
Distance
(ft)
SL-8
80
Distance
(ft)
100
100
La Costa Town Center
Carlsbad, Califomia
Project No.: 111399' Date: 12/1 i
120 140
120 140
SOUTHWEst
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Figure 4d
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Distance
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La Costa Town,Center
Carlsbad, California
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Project No.: 111399 D"te: 12/11
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SCS& T LEGEND
~rtific;ial fill '
~lluvium (potentially c;ompressible soil)
Delmar Formation
Metasedim~ntary and
metavolc;anic; roc;ks, undivided
Geologic; Contac;t
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loc;ation (reported by SCS& T, 2011)
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(reported by Geosoils, 1990)
Approximate test trenc;h loc;ation
(reported by Geosoils, 1982)
Approximate test boring loc;ation
(reported by Geosoils, 1982)
120'
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SCS& T LEGEND
Artificial fi II
Alluvium (potentially compressible soil)
. Delmar Formation
Metasedimentary and
metavolcanic rocks, undivided
Geologic contact
Cut/Fill transition line (approximate)
Subdrain alignment (approximate)
Lot number
120'
GRADING
Location
Lot Number 2 -12,
19 -23, 29, 30, and
60-64
Lot Numbers 14 -17,
34, 35, and 39 -51
Lot Numbers 13, 18,
24 -28, 31, 33, 52, 53,
55-59
Lot Numbers 32, 36,
37, 38, and 54
Requirement
Fill Lots, excavate
unsuitable soils prior to
placing fill, estimate 2 feet
of unsuitable soil
excavation
5-foot overexcavation
(Cut Lots)
5-foot overexcavation
(CuVFili Transition Lots)
10-foot overexcavation
(CuVFili Transition Lots)
Note: Horizontally, the excavation should extend at least 5 feet
outside perimeter footing lines or equal to the depth of
overexcavation, whichever is more.
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