HomeMy WebLinkAboutCT 04-11; POINSETTIA COMMONS; INTERIM GEOTECHNICAL REPORT OF ROUGH GRADING FOR PORTIONS OF BUILDING PADS 1-13; 2007-09-06ALBUS-KEEFE & ASSOCIATES, INC.
GEOTECHNICAL CONSULTANTS
September 6, 2007
J.N.: 1286.01
Mr. Ron Schulman
Trammell Crow Residential, Southern California
949 South Coast Drive, Suite 400
Costa Mesa, California 92626
Subject: Interim Geotechnical Report of Rough Grading for Portions of Building Pads
1 through 13, Poinsettia Commons, Avenida Encinas and Embarcadero Way,
City of Carlsbad, California.
Dear Mr. Schulman;
We are pleased to present to you our report of rough grading services for portions of building pads 1
through 13 within the subject Poinsettia Commons project. This report presents a summary of our
geotechnical observation and testing services provided during site rough grading operations as of thern
date of this report, as well as our conclusions and recommendations pertaining to future site
development based on the as-graded site conditions.
We appreciate this opportunity to be of service to you. If you have any questions regarding the
contents of this report, please do not hesitate to call.
Sincerely,
ALBUS-KEEFE & ASSOCIATES, INC.
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Patrick M. Keefe
Principal Enneeriogist
1011 North Armando Street, Anaheim CA 92806-2606 (714) 630-1626 FAX (714) 630-1916
Trammell Crow Residential, Southern California September 6, 2007
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TABLE OF CONTENTS
REPORT
1.0 INTRODUCTION ......................................................................................................................I
1.1 PURPOSE................................................................................................................................1
1.2 PROJECT LOCATION AND JURISDICTION .....................................................................1
1.3 SCOPE OF SERVICES...........................................................................................................1
2.0 SUMMARY OF ROUGH GRADING OPERATIONS .............................................................2
2.1 GENERAL...............................................................................................................................2
2.2 SITE PREPARATION (REMOVALS , OVEREXCAVATIONS & STOCKPILES) ..........2
2.3 FILL PLACEMENT................................................................................................................3
3.0 AS-GRADED GEOLOGIC CONDITIONS...............................................................................3
4.0 FIELD TESTING........................................................................................................................3
5.0 LABORATORY TESTING........................................................................................................3
6.0 CONCLUSIONS.........................................................................................................................4
6.1 COMPLIANCE STATEMENT AND SITE SUITABILITY .................................................4
6.2 GEOLOGIC HAZARDS.........................................................................................................4
6.2.1 Faulting and Ground Rupture ...........................................................................................4
6.2.2 Ground Shaking................................................................................................................4
6.2.3 Liquefaction......................................................................................................................5
6.2.4 Landsliding .......................................................................................................................5
6.3 GROUNDWATER..................................................................................................................5
6.4 SETTLEMENT .......................................................................................................................5
7.0 RECOMMENDATIONS............................................................................................................5
7.1 EARTHWORK........................................................................................................................5
7.1.1 General Earthwork and Grading Specifications ...............................................................5
7.1.2 Temporary Excavations ....................................................................................................5
7.1.3 Fill Placement ...................................................................................................................6
7.1.4 Fill Slopes .........................................................................................................................6
7.1.5 Cut Slopes.........................................................................................................................6
7.1.6 Import Material.................................................................................................................7
7.2 SEISMIC DESIGN PARAMETERS ......................................................................................7
7.3 FOUNDATIONS.....................................................................................................................7
7.3.1 General..............................................................................................................................7
7.3.2 Soil Expansion ..................................................................................................................7
7.3.3 Settlement .........................................................................................................................8
7.3.4 Allowable Bearing Value..................................................................................................8
7.3.5 Lateral Resistance.............................................................................................................8
7.3.6 Footings and Slabs on Grade ............................................................................................8
7.3.7 Footing Setbacks from Adjacent Structures .....................................................................9
7.4 RETAINING WALLS...........................................................................................................10
7.4.1 General............................................................................................................................10
7.4.2 Bearing Capacity, Lateral Resistance, and Reinforcement.............................................10
7.4.3 Earth Pressures................................................................................................................10
7.4.4 Drainage and Moisture-Proofing ....................................................................................10
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7.4.5 Retaining Wall Backfill ................................................................................... I
7.5 EXTERIOR SLABS AND FLAT WORK..............................................................
7.6 FOOTING OBSERVATIONS ............................................................................... 1
7.7 CEMENT TYPE.....................................................................................................
7.8 CORROSION POTENTIAL ...................................................................................
7.9 POST GRADING CONSIDERATIONS ............................................................... 12
7.9.1 Erosion Protection............................................................................................ 12
7.9.2 Site Drainage.................................................................................................... 12
7.9.3 Utility Trenches ............................................................................................... 12
7.9.4 Re-Certification of Pads................................................................................... 13
7.10 PLAN REVIEWS AND CONSTRUCTION SERVICES .................................. 13
8.0 CLOSURE .................................................................................................................. 14
REFERENCES.................................................................................................................... 15
MAPS
PLATES 1 through 3 - Plot Plans (pocket enclosures)
APPENDICES
APPENDIX A - SUMMARY OF FIELD DENSITY TEST RESULTS
Table A - Summary of Field Density Test Results
APPENDIX B - SUMMARY OF LABORATORY TEST RESULTS
I Table B-i - Summary of Maximum Density/Optimum Moisture Testing
Table B-2 - Summary of Expansion and Corrosion Testing
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1.0 INTRODUCTION
1.1 PURPOSE
This report presents a summary of geotechnical consulting services provided by Albus-Keefe &
Associates, Inc., during rough grading for portions of building pads 1, 2, and the subterranean
parking garage beneath buildings 3 through 13. Conclusions and recommendations pertaining to
future site development are also provided in this report. Rough grading reported herein was
accomplished for the purpose of building a mixed use residential and commercial development. The
development will include 78 residential units and approximately 27,600 square feet of
commercial/retail space, and a daycare center.
1.2 PROJECT LOCATION AND JURISDICTION
The layout of the site is shown on the plan entitled "Grading and Erosion Control Plans: Poinsettia
Commons", sheets 2 through 4 of 8, prepared by Project Design Consultants. These plans are used
as our base maps to present the approximate limits of rough grading under the purview of this report,
as well as approximate locations of our field density tests and the removal bottom elevations (Plot
Plan, Plates 1 through 3).
Construction was performed under the jurisdiction of the City of Carlsbad, California.
1.3 SCOPE OF SERVICES
Albus-Keefe & Associates, Inc., has provided geotechnical consulting services as described below:
. Provided observation during clearing and grubbing operations.
. Provided observation during removal of unsuitable earth materials.
Provided observation of overexcavation bottoms.
Provided observation and in-situ moisture and density testing of subterranean parking garage
sub grade.
Provided observation and field testing during scarification, moisture conditioning and
I compaction of exposed earth materials within removal and overexcavation bottoms, and
during fill placement within the site.
Provided laboratory testing of earth materials encountered during rough grading operations.
Preparation of this report summarizing our observations, results of field and laboratory
testing, as well as opinions and recommendations relative to future development of the site.
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2.0 SUMMARY OF ROUGH GRADING OPERATIONS
2.1 GENERAL
Albus-Keefe & Associates, Inc., performed field observation and testing services during rough
grading operations for the portions of the subject building pads. Rough grading operations under the
purview of this report were performed from July 25, 2007 through August 20, 2007 by West-Tech
Contracting, Inc.
At this time, rough grading has been completed to a minimum of 5 feet beyond the building
envelopes, as shown on Plates 1 through 3. Temporary 1:1 slopes have been created during
excavation of the subterranean parking garage and around the elevator pit in building 2. Additional
rough grading is required beyond the limits shown on the enclosed plans for construction of
proposed for retaining and screening walls, street and parking areas, and landscape areas. A
supplemental report for these areas will be prepared upon completion of rough grading.
2.2 SITE PREPARATION (REMOVALS , OVEREXCAVATIONS & STOCKPILES)
The subject building pads were cleared of deleterious debris and vegetation prior to rough grading
operations. The deleterious materials were generally disposed of offsite. Unsuitable earth materials,
including existing artificial fills, topsoil, and weathered terrace deposits, were then removed to
expose competent terrace deposits. Unsuitable materials generally varied from 2 feet to 4 feet below
the existing ground surface.
To provide uniform bearing conditions, building pads I and 2 were overexcavated a minimum of 2.5
feet below the base of the proposed footings. The overexcavations extended a distance of at least 5
feet beyond the outside edges of the building envelopes.
I The subterranean parking area (beneath proposed buildings 3 through 13) was excavated to the
parking garage subgrade (approximately 44 msl) and exposed uniform soil conditions across the
entire building pad, therefore, overexcavation was not considered necessary. In-situ moisture and
I . density testing was performed at subgrade of the subterranean parking garage to verify competent
bearing soil conditions.
I Removal bottom elevations for building pads 1 and 2 are indicated on the Plot Plans (Plates 1
through 3).
I Following completion of rough grading of building pad 1, excavated soil materials were
subsequently stockpiled for use as backfill material during future retaining walls to be constructed
throughout the site.
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2.3 FILL PLACEMENT
Prior to placement of engineered fill materials, the exposed ground was scarified to a depth of about
6 inches, moisture conditioned to a relatively uniform moisture content near or slightly above
optimum, and then compacted.
Following preparation of the exposed ground surface, fill was placed in lifts approximately 8 inches
in thickness; moisture conditioned to a relatively uniform moisture content near or slightly above
optimum, then mechanically compacted. Mechanical compaction was generally achieved by using a
rubber-tired dozer. Each lift was placed in a similar manner. Fill materials were derived from
removal and cut areas within the. development. Prior to placement of fill on surfaces inclined steeper
than approximately 5:1 (h:v), near vertical benches were cut into competent earth materials within
the adjacent ascending terrain.
The approximate limits of fill placed under the purview of this report are shown on the enclosed Plot
Plans (Plates 1 through 3).
3.0 AS-GRADED GEOLOGIC CONDITIONS
Periodic geologic observations were made during the subject rough grading to compare the
anticipated and as-graded geologic conditions. The geologic conditions that were mapped are
relatively similar to the anticipated conditions. Detailed descriptions of geologic units encountered
during rough grading are presented in our referenced investigation report dated January 9, 2004.
4.0 FIELD TESTING
The in-place density of fill materials was determined in accordance with ASTM D 1556 (6-inch sand
cone) and ASTM D 2922/D 3017 (nuclear gauge). In place density tests were taken at a minimum
rate of one test for every 1000 cubic yards and/or two vertical feet of material placed. The results of
field density tests were compared to the maximum density determined in accordance with ASTM D
1557-02, to evaluate relative compaction. Where test results indicated a relative compaction less than
90%, the area of substandard fill was either reworked until subsequent testing resulted in a relative
compaction equal to or greater than 90%, or the substandard material was removed. The results of
field density tests are presented in Table A provided in Appendix A. The approximate test locations
are shown on the enclosed Plot Plans (Plates I through 3).
5.0 LABORATORY TESTING
Representative samples of the onsite soils were collected and tested in the laboratory during the rough
grading operations. Descriptions of the laboratory testing performed are provided below:
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Maximum dry density and optimum moisture content tests were performed on selected samples in I general conformance with ASTM D 1557-02. Pertinent test values are presented in Table B-I
provided in Appendix B.
Expansion Index tests were performed on representative earth materials encountered near finish pad
grades during rough grading operations. Expansion Index testing was completed in accordance with I California Building Code (C.B.C.) Standard 18-2. Test results are presented in Table B-2 provided in
Appendix B.
Corrosion analyses, which include soluble sulfate content, chloride content, minimum resistivity,
and pH, were performed on selected samples by GeoLogic Associates of Anaheim, California.
These tests were performed in accordance with California Test Methods (CTM) 417, CTM 422,
CTM 643 and CTM 643, respectively. The test results are presented in Table B-2 (Appendix B).
6.0 CONCLUSIONS
6.1 COMPLIANCE STATEMENT AND SITE SUITABILITY
Earthwork carried out under the observation and testing by Albus-Keefe & Associates, Inc., was ' performed in substantial conformance with the project plans and specifications, the grading codes of
the City of Carlsbad, and applicable portions of the project geotechnical requirements. (Albus-Keefe
& Associates, Inc., is not responsible for line and grade.)
The rough-graded building envelope areas, as shown on Plates 1 through 3, are considered suitable
for their intended use, provided that the recommendations presented herein and in our referenced
geotechnical reports are implemented during future grading and construction. Rough grading work
for the site has been observed and tested in a manner consistent with the standard of care currently
exercised by members of the profession practicing in the same general locality under similar
conditions:
6.2 GEOLOGIC HAZARDS
6.2.1 Faulting and Ground Rupture
No active faults are known to project through the site nor does the site lie within the bounds of an
"Earthquake Fault Studies Zone" as defined by the State of California in the Alquist-Priolo
Earthquake Fault Zoning Act. As such, the potential for ground rupture due to fault displacement
beneath the site is-considered remote.
6.2.2 Ground Shaking
The site is located in a seismically active area that has historically been affected by moderate to
occasionally high levels of ground motion. The site lies in close proximity to several active faults;
therefore, during the life of the proposed development, the property will probably experience
moderate to occasionally high ground shaking from these fault zones, as well as some background
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shaking from other seismically active areas of the southern California region. Potential ground
I accelerations have been evaluated for the site and are presented in our referenced geotechnical
reports. In addition, seismic design parameters as required by the 2001 CBC are presented in
I Section 7.1.
6.2.3 Liquefaction
I All of the subject building pads are supported by compacted fills overlying dense terrace deposits or
directly by dense terrace deposits. Based on the characteristics of these materials, the potential for
liquefaction at the subject lots is considered negligible.
I 6.2.4 Landsliding
The subject site is positioned at the top. of a wide, flat, terrace feature. As such, geologic hazards
I associated with landsliding ate not anticipated at the subject site.
6.3 GROUNDWATER
Adverse effects from groundwater or seepage are not anticipated at the subject site provided that
future surface water is controlled to limit excessive subsurface infiltration from irrigation or
concentrated runoff and that basement retaining wall subdrains are properly constructed and
maintained throughout the life of the proposed development.
6.4 SETTLEMENT
Based on the as-graded site conditions, total and differential settlements due to foundation loads are
not anticipated to exceed 1 inch and Y2 inches over 30 feet, respectively. These estimated
settlements are considered within tolerable limits for the proposed structures.
7.0 RECOMMENDATIONS
7.1 EARTHWORK
7.1.1 GeneralEarthwork and Grading Specifications
Future earthwork and grading should be performed in accordance with all applicable requirements of
Cal/OSHA, applicable specifications of the Grading Codes of the County of San Diego and/or the
City of Carlsbad, California, in addition to recommendations presented herein.
7.1.2 Temporary Excavations
Temporary excavations may be cut vertically up to a height of 5 feet provided that no adverse
geologic conditions or surcharging of the excavations are present. Temporary excavations in soil
materials that are greater than 5 feet in height should be laid back at a maximum gradient of IH:lV
provided there are no adjacent structures, stockpiles, heavy equipment, or other surcharges located
within 5 feet of the excavation. If such excavations cannot be laid back, shoring and/or rakers may
be required. If shoring and/or rakers are required, the geotechnical engineer should be notified as
additional recommendations will be required.
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The project geologist or soil engineer should observe all temporary excavations to confirm that
conditions are as anticipated herein, the excavations are stable, and to provide specific
recommendations in the event conditions differ. All temporary excavations should conform to the
requirements of CAL OSHA.
7.1.3 Fill Placement
In general, materials excavated from the site may be used as fill provided they are free of deleterious
materials and particles greater than 6 inches in maximum dimension. Following removal of
unsuitable materials, the exposed ground should be scarified to a depth of 6 inches, brought to a
uniform moisture content of 100 to 125 percent of optimum, then compacted to at least 90 percent of
the laboratory standard.
Fill materials should be placed in lifts no greater than approximately 8 inches in thickness. Each lift
should be watered or air dried as necessary to achieve a uniform moisture content slightly greater
I than optimum, and then compacted in place to at least 90 percent of the laboratory standard. Each
lift should be treated in a similar manner. Subsequent lifts should not be placed until the project
geotechnical consultant has approved the preceding lift. Lifts should be maintained relatively level
and should not exceed a gradient of 20H:IV. When placing fill on ground sloping steeper than 5:1
(H:V), vertical benches should be excavated into competent native earth materials.
I The laboratory standard for maximum dry density and optimum moisture content for each change in
soil type should be determined in accordance with Test Method ASTM D 1557-98.
1 7.1.4 Fill Slopes
Fill slopes should be constructed with a keyway having a minimum width of 15 feet and a minimum
I embedment of 2 feet into competent materials. Where practical, fill slopes should be constructed by
over filling and trimming to a compacted core. The face of slopes that are not over-built should be
backrolled with a sheepsfoot roller at least every 4 vertical feet of slope construction. The process
I should provide compacted fill to within 12 inches of the slope face. Finished slopes should be track-
walked with a small dozer in order to compact the slope face. The slope face materials will tend to
dry out prior to final face compaction. As such, the addition of water to the slope face will likely be
I required prior to compaction to achieve the required degree of compaction at the time of slope face
compaction.
1 7.1.5 Cut Slopes
Cut slopes into terrace deposits should be inspected at intervals not exceeding 10 feet during rough
I grading by an engineering geologist, to evaluate the competency of the slope and to identify any
local adverse geologic conditions (i.e. friable or running sands) that may be encountered during
slope construction. If local adverse geologic conditions are encountered during cut slope
I construction, portions of the slope may require replacement with a stabilization fill or other
acceptable alternative. Corrective measures should be made as the slope is being constructed.
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7.1.6 Import Material
If earth materials are imported to the site to balance the cut and fill rough grading, the proposed
import soil should have Very Low Expansion Index (<20) and Plastic Index (PT) less than 15.
Samples of all import sources should be provided to the geotechnical consultant prior to hauling the
materials to the site so that appropriate testing and evaluation of the proposed fill material can be
performed in advance.
7.2 SEISMIC DESIGN PARAMETERS
For design of the project in accordance with the 2001 CBC, seismic design factors as defined by
Chapter 16 are presented in Table 7.1 below.
TABLE 7.1
CBC Seismic Design Parameters
Parameter I Value
Seismic Zone Factor, Z 0.4
Soil Profile Type, S Sc
Near Source Factor, Na 1.0
Near Source Factor, Nv 1.2
Seismic Coefficient, Ca 0.40
Seismic Coefficient, Cv 0.65
7.3 FOUNDATIONS
7.3.1 General
Recommendations for conventional foundations are provided herein. These recommendations have
been based on typical site materials exposed during rough grading and our experience with similar
projects.
7.3.2 Soil Expansion
Testing of typical site soils performed during rough grading indicates a Very Low potential for
expansion (CBC Table 18-1-13). Based on this very low expansion potential, special design for
expansive soils in accordance with Section 1 815 of the 1997 UBC is not required. The expansion
test results are provided in Table B-2 of Appendix B. The recommendations presented herein for
foundations and slabs on grade are based on soils with Very Low expansion potential.
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I 7.3.3 Settlement
Total and differential settlement is not anticipated to exceed 1 inch and '/2 inch over 30 feet,
I respectively. The estimated magnitudes of settlement should be considered by the structural
engineer in design of the proposed structures.
1 7.3.4 Allowable Bearing Value
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A bearing value of 2500 pounds per square foot may be used for continuous and isolated footings
founded at a minimum depth of 12 inches below the lowest adjacent grade and having a minimum
width of 12 inches. The bearing value may be increased by 200 psf and 500 psf for each additional
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foot in width and depth, respectively up to a maximum value of 3500 psf Recommended allowable
bearing values include both dead and live loads, and may be increased by one-third for wind and
seismic forces.
1 7.3.5 Lateral Resistance
I A passive earth pressure of 350 pounds per square foot per foot of depth up to a maximum value of
3500 pounds per square foot may be used to determine lateral bearing for footings against level,
compacted soil. This lateral resistance is based on footings located a horizontal distance away from
I slopes equal to at least twice the footing depth. Footings placed closer (or walls having a descending
slope below the face of the wall) should utilize a passive pressure of 100 pounds per square foot per
foot of depth. A coefficient of friction of 0.37 times the dead load forces may also be used between
I concrete and the supporting soils to determine lateral sliding resistance. An increase of one-third of
the above values may also be used when designing for wind and seismic forces. These values may
be considered ultimate design values.
The above values are based on footings placed directly against competent native soils or compacted
fill. In the case where footing sides are formed, all backfill against the footings should be compacted
to at least 90 percent of the laboratory standard.
The bottom outer edge of foundations located adjacent a slope should be setback from the slope face
a horizontal distance of at least 7 feet.
7.3.6 Footings and Slabs on Grade
Exterior building footings may be founded at the minimum depths indicated in CBC Table 18-I-C
(i.e., 18-inch minimum depth for two-story construction, and 24-inch minimum depth for three-story
construction). Interior bearing wall footings for both two-story and three-story construction may be
founded at a minimum depth of 18 inches below the lowest adjacent finish grade. All continuous
footings should be reinforced with a minimum of two No. 4 bars, one top and one bottom. The
structural engineer may require different reinforcement and should dictate if greater than the
recommendations herein.
Interior isolated pad footings should be a minimum of 24 inches square and founded at minimum
depths of 18 inches below the lowest adjacent final grade for two-story and three-story construction.
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Exterior isolated pad footings intended for support of patio covers, upper decks, and similar
construction should be a minimum of 24 inches square and founded at a minimum depth of 18
inches below the lowest adjacent final grade. Specific recommendations for construction of column
footings in close proximity to proposed subterranean parking garage retaining walls are provided in
the following section.
Interior concrete slabs constructed on grade should be a nominal 4 inches thick and should be
I reinforced with 6-inch by 6-inch, W2.9 X W2.9 (No. 6 by No. 6) reinforcing wire mesh or No. 3
bars spaced 24 inches each way. Care should be taken to ensure the placement of reinforcement at
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mid-slab height. The structural engineer may recommend a greater slab thickness and reinforcement
based on proposed use and loading conditions and such recommendations should govern if greater
than the recommendations presented herein.
All dwelling area floor slabs constructed on-grade should be underlain with a moisture vapor barrier
consisting of a polyvinyl chloride membrane such as 10-mil Visqueen or equivalent. A minimum of
two (2) inches of clean sand having an SE of at least 30 should be placed over the membrane to
promote uniform curing of the concrete. This vapor barrier system is anticipated to be suitable for
most flooring finishes that can accommodate some vapor emissions. However, this system may emit
I more than 4 pounds of water per 1000 sq. ft. and therefore, may not be suitable for all flooring
finishes. Additional steps should be taken if such vapor emission levels are too high for anticipated
flooring finishes.
I Garage floor slabs should have a nominal thickness of 4 inches and should be reinforced in a similar
manner as living floor slabs. Garage floor slabs should also be poured separately from adjacent wall
I footings with a positive separation maintained with 3/8-inch minimum felt expansion joint materials,
and quartered with saw cuts or cold joints. Consideration should be given to providing a vapor
barrier below the garage slab to mitigate the potential for effervescence on the slab surface.
I Block-outs should be provided around interior columns to permit relative movement and mitigate
distress to the floor slabs due to differential settlement that will occur between column footings and
adjacent floor subgrade soils as loads are applied.
Prior to placing the vapor barrier system, subgrade soils below slab-on-grade areas should be
I' thoroughly moistened to provide a moisture content that is equal to or greater than 100 percent of the
optimum moisture content to a depth of 12 inches.
I 7.3.7 Footing Setbacks from Adjacent Structures
The southern edge of Building 2 appears to be approximately 5 feet from the wall for the
subterranean level of Building 3. The column footings along the southern side of Building 2 should
I either be deepened to avoid loading this subterranean wall; or the subterranean wall designed to
support the footings; or this edge of Building #2 could be designed to be supported on this
I subterranean wall; or similar concept. Specific recommendations have been provided in our
referenced report dated March 2, 2007 that discuss surcharges on the subterranean parking garage
retaining walls.
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7.4 RETAINING WALLS
1 7.4.1 General
The following preliminary design and construction recommendations are provided for genera!
I retaining walls. The structural engineer and architect should provide appropriate recommendations
for sealing at all joints and water proofing material on the back of the walls.
I 7.4.2 Bearing Capacity, Lateral Resistance, and Reinforcement
Retaining walls may utilize the bearing capacities and lateral-bearing values provided for
I conventional foundations as discussed in Section 7.3. All continuous footings should be reinforced
with a minimum of two No. 4 bars, one top and one bottom.
7.4.3 Earth Pressures
Conventional retaining walls should be designed for a minimum of the pressures indicated in the table
below. The values are based on typical onsite materials as well as on drained backfill conditions and
do not consider hydrostatic pressures. Relatively clayey materials should not be used for wall backfill.
All walls should be designed to support any adjacent structural surcharge loads imposed by other
nearby walls, footings, traffic, and construction equipment in addition to the earth pressures provided in
Table 7.2 below. These values are considered ultimate design values.
Table 7.2
Retaining Wall Earth Pressures
Active Pressure Restrained Walls Backfill Wall Height up to 15 feet all Heights Condition (pci) (pci)
Level 40 65
All retaining walls should be constructed with a backdrain system to prevent moisture buildup as
described below.
7.4.4 Drainage and Moisture-Proofing
All retaining walls should be constructed with a perforated pipe and gravel subdrain to prevent
entrapment of water in the backfill. The perforated pipe should consist of 4-inch-diameter, ABS
SDR-35 or PVC Schedule 40 with the perforations laid down along the base of the gravel. The pipe
should be embedded in 3/4 to I Y2-inch open-graded gravel wrapped in filter fabric. The gravel
should be at least one foot wide and extend at least one foot up the wall above the footing. Filter
fabric should consist of Mirafi 140N, or equal. Outlet pipes should be directed to positive drainage
devices.
The use of weepholes may be considered in locations where aesthetic issues from potential nuisance
water are not a concern. Weepholes should be 2 inches in diameter and provided at least every 6 feet
on center. Where weepholes are used, perforated pipe may be omitted from the grave! subdrain.
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Retaining walls supporting backfill should also be coated with a waterproofing compound or
covered with such material to inhibit infiltration of moisture through the walls. Waterproofing
material should cover any portion of the back of the walls that will be in contact with soil and should lap
over and cover the top of footing. The top of footing should be finished smooth with a trowel to inhibit
the infiltration of water through the wall. The project structural engineer should provide specific
recommendations for water proofing, water stops, and joint details.
7.4.5 Retaining Wall Backfill
Onsite, granular soils may generally be used for backfill of retaining walls. Relatively clayey
materials should not be used for wall backfill. The project geotechnical consultant should approve all
backfill used for retaining walls. All wall backfill should be brought to a uniform moisture slightly
over optimum, placed in lifts no greater than 12 inches in thickness, and then mechanically
compacted with appropriate equipment to at least 90 percent of the laboratory standard. Flooding or
jetting of backfill material is not recommended.
7.5 EXTERIOR SLABS AND FLAT WORK
Exterior flatwork should be a nominal 4 inches thick. Cold joints or saw cuts should be provided at
least every 10 feet in each direction. Subgrade soils below flatwork should be moistened to a
moisture content of at least 100 percent of the optimum to a depth of 12 inches. Moistening should
be accomplished by lightly spraying the area over a period of a few days just prior to placing
concrete.
7.6 FOOTING OBSERVATIONS
All footing trenches for buildings and walls should be observed by the project geotechnical
consultant to verify that they have been excavated into competent bearing soils and to the minimum
embedments recommended herein. These observations should be performed prior to placement of
forms or reinforcement. The excavations should be trimmed neat, level and square. All loose,
sloughed or moisture softened materials and debris should be removed prior to placing concrete.
7.7 CEMENT TYPE
Based on laboratory testing of selected soil samples obtained from the site, onsite soils are
anticipated to contain less than 0.10% soluble sulfate concentrations. As such, we recommend that
the procedures provided in the 2001 CBC Section 1904.3 and Table 19-A-4 for concrete exposed to
sulfate-containing solutions be followed for Negligible Sulfate Exposure.
7.8 CORROSION POTENTIAL
Laboratory testing for soluble chloride content, resistivity, and pH were completed on representative
samples collected near pad grades. Test results for chloride content do not indicate a corrosive
environment to ferrous metals. However, site soils do indicate a minimum resistivity less than 2,000
ohm-cm. As such, site soils may be considered corrosive to ferrous metals. Structures fabricated
from steel or other ferrous metals should have appropriate corrosion protection if they will be in
ALBUS-KEEFE & ASSOCIATES, INC.
Trammell Crow Residential, Southern California September 6, 2007
J.N.: 1286.01
I Page 12
contact with site soils. Under such conditions, a corrosion specialist should provide specific
recommendations. Test results also indicate that the pH level of the site soil is slightly alkaline and
within a normal range.
7.9 POST GRADING CONSIDERATIONS
7.9.1 Erosion Protection
The site should incorporate temporary erosion protection during grading. Protection may include silt
fencing, sandbags, landscape elements or other methods as required by local authorities. The
I .temporary measures should be maintained until permanent site improvements have been
incorporated within the development to sufficiently provide erosion protection.
I 7.9.2 Site Drainage
Positive drainage devices, such as sloping concrete flatwork, graded swales, and/or area drains,
I should be provided around the new construction to collect and direct all surface water to suitable
discharge areas. No rain or excess water should be directed toward or allowed to pond against
structures such as walls, foundations, flatwork, etc.
Excessive irrigation water can be detrimental to the performance of the proposed site development.
Water applied in excess of the needs of vegetation will tend to percolate into the ground. Such
percolation can lead to nuisance seepage and shallow perched groundwater. Seepage can form on
slope faces, on the faces of retaining walls, in streets, or other low-lying areas. These conditions
could lead to adverse effects such as the formation of stagnant water that breeds insects, distress or
damage of trees, surface erosion, slope instability, discoloration and salt buildup on wall faces, and
premature failure of pavement. Excessive watering can also lead to elevated vapor emissions within
structures that can damage flooring finishes or lead to mold growth inside the home.
Key factors that can help mitigate the potential for adverse effects of overwatering include the
judicious use of water for irrigation, use of irrigation systems that are appropriate for the type of
vegetation and geometric configuration of the planted area, the use of soil amendments to enhance
moisture retention, use of low-water demand vegetation, regular use of appropriate fertilizers, and
seasonal adjustments of irrigation systems to match the water requirements of vegetation. Specific
recommendations should be provided by a landscape architect or other knowledgeable professional.
7.9.3 Utility Trenches
Trench excavations should be constructed in accordance with the recommendations contained in
Section 7.1 .2 of this report. All trench excavations should conform to the requirements of
Cal/OSHA.
Trench backfill materials and compaction criteria should conform to the requirements of the local
municipalities. As a minimum, utility trench backfill should be compacted to at least 90 percent of
the laboratory standard. Trench backfill should be brought to a uniform moisture content slightly
over optimum, placed in lifts no greater than 12 inches in thickness, and then mechanically
compacted with appropriate equipment to at least 90 percent of the laboratory standard. The project
A LB US-KEEFE & ASSOCIA TES, INC.
Trammell Crow Residential, Southern California September 6, 2007
J.N.: 1286.01
I Page 13
geotechnical consultant should perform density testing, along with probing, to verify adequate
compaction. Site conditions are generally not suitable for jetting of trench backfill.
Within shallow trenches (less than 18 inches deep) where pipes may be damaged by heavy
compaction equipment, imported clean sand having a Sand Equivalent of 30 or greater may be
utilized. The sand should be placed in the trench, thoroughly watered, and then compacted with a
vibratory compactor.
Where utility trenches are proposed parallel to any building footing (interior, and/or exterior
I trenches), the bottom of the trench should not be located below a 1:1 (H:V) plane projecting
downward from the outside edge of an adjacent footing base. For utility trenches located below a
1:1 (H:V) plane projecting downward from the outside edge of an adjacent footing base or crossing
footing trenches, concrete or slurry should be used as trench backfill.
I 7.9.4 Re-Certification of Pads
If structures are not constructed on pads within approximately 6 months following completion of
rough grading and/or if the pads are used for any other purpose (i.e. stockpiling, temporary parking,
I' etc.) the pads should be re-evaluated by the project geotechnical consultant to confirm they are still
suitable for use prior to building construction. Pads that become overly desiccated or wet may
require minor remedial earthwork to restore proper moisture and compaction near the surface prior
to building construction.
7.10 PLAN REVIEWS AND CONSTRUCTION SERVICES
We recommend Albus-Keefe & Associates, Inc., be engaged to review all development plans and
I specifications prior to other phases of construction for the site. .This is to verify that the
recommendations contained in this report have been properly interpreted and are incorporated into the
project specifications. If we are not provided the opportunity to review these documents, we take no
I responsibility for misinterpretation of our recommendations.
We also recommend that Albus-Keefe & Associates, Inc., be retained to provide soil engineering
I services during future construction for the site (i.e. excavation and foundation work). This is to
observe compliance with the design, specifications or recommendations, and to allow design changes
I
in the event that subsurface conditions differ from those anticipated prior to the start of construction.
If the project plans change significantly, the project geotechnical consultant should review our
original design recommendations and their applicability to the revised construction. If conditions are
encountered during construction that appear to be different than those indicated in this report, the
project geotechnical consultant should be notified immediately. Design and construction revisions
may be required.
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ALB US-KEEFE & ASSOCIA TES, INC.
Trammell Crow Residential, Southern California September 6, 2007
J.N.: 1286.01
I Page 14
8.0 CLOSURE
This report has been prepared for the exclusive use of Trammell Crow Residential, Southern
California. Professional judgments presented in this report are based on evaluations of the technical
information gathered, on construction procedures observed by representatives of this firm, and on our
general experience in the field of geotechnical engineering. Our engineering work and judgments
rendered meet the standard of care of our profession at this time and locale. We do not guaranty or
warranty the performance of the project in any respect.
We hope that this report fulfills the current needs of the project. If you have any questions, or require
additional information, please contact the undersigned.
Respectfully submitted,
ALBUS-KEEFE & ASSOC C.
T.
Douglas
. Abernathy Michael Putt
Senior Engineer Project Geologist
G.E. 2547 C.E.G. 2341
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ALB US-KEEFE & ASSOCIATES, INC.
Trammell Crow Residential, Southern California September 6, 2007
J.N.: 1286.01
Page 15
REFERENCES
Reports
Albus-Keefe & Associates, Inc., "Preliminary Geotechnical Investigation, Proposed Carlsbad
Transit Village, City of Carlsbad, California", (J.N. 1286.00), dated January 9, 2004.
Albus-Keefe & Associates, Inc., "Grading Plan Review, Proposed Mixed Use Development,
Avenida Encinas and Embarcadero Way, City of Carlsbad, California", (J.N. 1286.01), dated
June 9, 2006.
Albus-Keefe & Associates, Inc., "Structural Foundation Plan Review, Proposed Mixed Use
Development, Poinsettia Commons, City of Carlsbad, California", (J.N. 1286.01), dated
March 2, 2007.
Plan
Project Design Consultants, "Grading and Erosion Control Plans for Poinsettia Commons, City
of Carlsbad", Sheets 2 through 4 of 8, Scale: 1" = 20', dated April 2, 2007.
ALBUS-KEEFE & ASSOCIA TES, INC.
- - - - - - - - - - - - - - - - - - - Trammell Crow Residential TABLE A September 6, 2007
J.N.: 1286.01
SUMMARY OF FIELD DENSITY TEST RESULTS
Test
Number
Test
Date
Test
Type
(*)
Location Elev./
Depth
(ft.)
Moist.
Content
(%)
Dry
Density
(pcf)
Max. Dry
Density
(pcf)
Opt.
Moist
(%)
Max.
Curve
No.
Rel.
Comp
NO
Req.
Comp
(%)
Pass!
Fail
(P/F)
(Northing)
(Tract)
(Easting)
(Lot)
1 07/26/07 S 5288 4870 50.0 13.7 111.3 127.5 11.5 A 87 90 F
I A 07/26/07 5 5288 4870 50.0 13.5 116.2 127.5 11.5 A 91 90 P
2 07/26/07 S Test Number Not Used
3 07/26/07 S 5221 4833 52.0 12.6 122.5 131.5 10.5 B 93 90 P
4 07/27/07 S 5315 4815 54.0 11.4 121.4 131.5 10.5 B 92 90 P
5 07/30/07 N 5225 4905 56.0 3.9
-
117.7 127.5 11.5 A 92 90 P
FG 6 07/31/07 N 5254 4871 57.6 12.6 123.1 131.5 1 10.5 B 94 90 P
FG 7 07/31/07 N 5328 4843 57.6 - 3.4 121.6 131.5 10.5 B 92 90 P
FG 8 07/31/07 N 5195 4868 57.6 11.5 117.9 129.0 10.0 C 91 90 P
9 08/01/07 N 5327 4586 50.0 10.6 120.3 129.0 10.0 C 93 90 P
10 08/01/07 N 5260 4682 52.0 1.2 - 114.5 129.0 10.0 C 89 90 F
IOA 08/01/07 N 5260 4682 52.0 12.5 116.8 129.0 10.0 C 91 90 P
11 08/01/07 N 5324 4672 54.0 1 2.0 . 122.4 131.5 10.5 B 93 90 P
12 08/02/07 5 5222 4602 56.0 12.9 123.9 131.5 10.5 B 94 90 P
FG 13 08/03/07 N 5280 4609 57.1 11.5 - 19.7 129.0 10.0 C 93 90 P
14 08/03/07 N 5282 4691 57.8 10.2 119.0 129.0 10.0 C 92 90 P
15 08/03/07 N 5357 4632 58.0 11.5 118.9 129.0 10.0 C 92 90 P
FG 16 08/14/07 N 5114 4674 44.0 11.8 - 19.1 129.0 10.0 C 92 90 P
FG 17 08/14/07 N 4958 4720 44.0 12.0 20.6
_
131.5 10.5 B 92 90 P
PG 18 08/14/07 N 4830 4739 44.0 11.5 119.5 129.0 10.0 C 93 90 P
FG 19 08/14/07 N 4763 4830 44.0 12.8 122.4 131.5 10.5 B 93 90 P
FG 20 08/14/07 S 4616 4858 44.0 12.1 123.0 131.5 10.5 B 94 90 P
FG 21 08/15/07 N 4667 4932 44.0 12.7 121.7 131.5 10.5 B 93 90 P
FG 22 08/15/07 N 4810 4855 44.0 11.5 120.3 129.0 10.0 C 93 90 P
FG 23 08/17/07 N 4875 4824 44.0 10.8 119.6 129.0 10.0 C 93 90 P
PG 24 08/17/07 N 5028 4786 44.0 12.2 1 121.6 129.0 10.0 1 C 94 90 P
* See last page of this table for explanations.
ALB US-KEEFE & ASSOCIATES, INC.
Page A-i
Trammel! Crow Residential *
TABLE A September 6 2007
J.N.: 1286.01
SUMMARY OF FIELD DENSITY TEST RESULTS '
Test
Number
.Uest T
Date
1't:
Type
Litjo1
Depth
(ft)
Content
(%
Density
(f)
1VIax.iry
Désity
(pcf)
Ojt.
Moist
('V0)
Ciir'e
No
Comp
(4V0)
Req..
Comp
(%)
Ps/
Fail
(P/F)
(Northing)
(Tract)
(Easting)
(Lot)
FG 25 08/17/07 N 5134 4710 44.0 11.6 120.4 129.0 10.0 C 93 90 P
FG .26 08/17/07 N 5185 4695 44.0 11.0 123.0 131.5 10.5 B ,94 90 P
27 08/20/07 N 4950 4804 45.0 12.3 120.1 129.0 - 10.0 C 93 90 p
28 08/20/07 - N 4959 4820 47.0 10.5 119.2 129.0 10.0 C 92 90 P
29 08/20/07 N 4952 P4831 49.0 . 11.9 121.5 129.0 10.0 C 94 90 P
30 08/20/07 N . 4966 . 4832 1 51.0 12.3 119.8 . 129.0 10.0 C 93 90 P
- - - - - - - - - - - - - - - - - - - September 6, 2007
J.N.: 1286.01
Trammell Crow Residential
TABLE A
EXPLANATION OF TEST CODES
PREFIX CODE DESIGNATION FOR TEST NUMBERS
OG- Original Ground SF- Slope Face
SG- Segmental Wall SR- Slope Repair
RW- Retaining Wall RG- Rough Grade
FG- Finish Grade VW- Verdura Wall
CODES FOLLOWING THE TEST NUMBER
A: Subsequent retest of failed density test after fill reconditioning and recompaction.
Failed material removed.
TEST TYPE
D: Drive-Cylinder Test per ASTM D2937
Sand Cone Test per ASTM D1556
N: Nuclear Gauge Test per ASTM D2922 and D3017
MAX. CURVE NO
A-F: Corresponds to Max Curve Designation listed in Table B-i (represents the laboratory maximum dry
density/optimum moisture content for a representative fill material encountered during grading).
ALB US-KEEFE & ASSOCIA TES, INC.
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SUMMARY OF LABORATORY TEST RESULTS / -(
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Trammell Crow Residential, Southern California September 6, 2007
J.N.: 1286.01
TABLE B-i
Summary of Maximum Density/Optimum Moisture Testing
Max
Curve No Description Test Results
A Tan / Yellowish-Brown Maximum Dry Density: 127.5 pcf
Silty Sand (SM) Optimum Moisture: 11.5%
B Reddish- to Yellowish-Brown Maximum Dry Density: 131.5 pcf
Silty Sand (SM) Optimum Moisture: 10.5%
Reddish- to Yellowish-Brown Maximum Dry Density: 129.0 pcf
Silty Sand (SM) Optimum Moisture: 10.0%
TABLE B-2
Summary of Expansion and Corrosion Testing
Building/ Expansion Soluble Sulfate Minimum Chloride
Pad No. Index Content pH Resistivity Content
(% of Weight) (ohm-cm) (ppm)
1 0 0.018 - - -
2 0 0.032 7.8 1650 53.5
9 0 0.007 - - -
11 8 0.022 - - -
ALB US-KEEFE & ASSOCIA TES, INC.